DENTAL ARTICLES AND BOOKS

The Right and Wrong Ways to Brush

2011-09-30T14:46:00.000+03:00

Most people start brushing their teeth as toddlers, so one might think that by the time we reached adulthood, we’d be professionals at it. Assuming one brushes twice a day for 20 years, that’s approximately 14,600 practice sessions. But each of us has probably seen our share of patients whose teeth make it evident that those 14,600 brushings have been done the wrong way. We are often asked about sensitive teeth and what can be done to manage the condition. Excessive tooth wear and gingival recession, which can lead to dentin hypersensitivity, are just a few of the problems we see resulting from overzealous brushing. How can such a seemingly simple act trip up so many people? How can we help our patients learn and maintain the proper technique?
We know there are multiple factors in brushing that can contribute to tooth wear, and it is not always evident which factor, or combination of factors, is responsible when we see a patient with obvious abrasion or recession. In these cases, hygienists should review the list of possible causes with the patient in order to identify the culprit(s). The list can be difficult to remember, but we can give our brains a helping hand with a simple mnemonic device: “Make Brushing Feel Truly Fantastic Again.” Each of these words corresponds to a factor in the proper toothbrushing checklist.

MOTION

The brushing motion most associated with tooth wear is the horizontal technique,¹ which seems to be the default setting for many patients. This can be a difficult factor
to correct, since it becomes so ingrained in muscle memory after years of daily repetition. It can also give patients the very satisfying feeling of cleaning their teeth extra thoroughly. But this action has been found to cause two to three times more wear on the dentin than an up-and-down motion.² Demonstrate a rolling, circular motion at a 45° angle to the tooth for patients who brush side-to-side, and emphasize that brushing this way can help prevent gingival recession. This motion can be described as the combination of the benefits of both side-to-side and up-and-down techniques. It also lessens the chance of applying too much force. Make sure gentle contact is made with the gum tissues, being mildly assertive but not aggressive with the brush. If the patient does not floss regularly, this also presents a good opportunity to suggest flossing as an additional way to get that extra-clean feeling.

BRISTLES

New evidence has surfaced in recent years that challenges the advice many of us have given patients regarding bristle stiffness and the importance of using a soft-bristled toothbrush. A study in the United Kingdom revealed that soft-bristled toothbrushes actually cause more abrasion than hard bristles. The study’s authors theorize that soft bristles retain more toothpaste than hard bristles, and dentifrice may cause most of the tooth wear. However, the researchers also state that the differences they found between the brushes were “probably of little clinical significance,” and did not recommend the adoption of hard bristles, especially considering the damage they may cause to soft tissues.³
To compare, brushing with harder bristles is similar to using an abrasive cloth to wash your car—it would certainly clean the car, but damage will be done to the finish as well. Soft bristles, then, still seem to be a safe choice for most patients, particularly when proper brushing protocol is observed. Using warmer water when brushing can help soften brush bristles, and cause a less sensitive feeling in the teeth.

FORCE

Estimates vary as to the ideal amount of force to apply when brushing. Not surprisingly, the optimum brushing force for efficacy in plaque removal does not necessarily correspond with the optimum force in preventing gingival abrasion. At least one study has questioned whether there is a strong link between brushing force and gingival abrasion.⁴
In light of these conflicting findings, the simplest step hygienists can take to identify problem brushers is asking what the patient’s toothbrush looks like. If the bristles have been flared out to the sides of the brush, the patient is applying too much pressure. Scrubbing is not necessary as plaque is soft. Hygienists can recommend the use of a power toothbrush, which has been shown to reduce brushing force.⁵ Some are designed to stop moving if too much pressure is applied.
Patients can also use a manual brush with a flexible neck designed to prevent excess force. Encourage patients to hold the brush gently with a few fingers, not using a strong-fisted grip on the handle.

TIME

Experts recommend brushing teeth for 2 to 3 minutes, but studies have found the actual average for most patients to be about 60 seconds.⁶ Because of this, time spent brushing is unlikely to be a causative factor for tooth wear in most patients. However, if a patient makes the other suggested changes to her brushing regimen and feels she is not getting her teeth as clean as she used to, the hygienist or assistant can suggest she compensate by increasing the amount of time she spends brushing. Patients can use this extra time to make sure all surfaces are being brushed, including gently brushing the tongue. Some patients find it helpful to use an egg timer to correctly gauge their brushing time.

FREQUENCY

There is a clear link between gingival recession and the frequency of toothbrushing.⁷ It is recommended that patients brush twice a day, which is particularly true in the case of patients using an anti-sensitivity toothpaste. However, patients who brush more than twice a day should be instructed that the practice is likely to do more harm than good, since studies have found few benefits from increased brushing frequency that would outweigh the additional abrasion.⁸ If a patient likes to “freshen up” after a meal or before going out, hygienists or assistants can suggest swishing with mouthwash. Patients also should be instructed not to brush immediately after consuming acidic foods and beverages, as this can lead to increased risk for tooth wear and erosion.

ABRASIVITY

Patients often think only of their toothbrush as a cause of abrasion, but dentifrice can also contribute to enamel loss.⁹ Studies have shown that brushing without dentifrice can adequately clean teeth, but dentifrice is the agent that prevents staining. All toothpastes must have some degree of abrasivity to function, but it can be difficult to determine just how abrasive a toothpaste is by looking at the package. Hygienists or assistants also can suggest patients simply use a smaller amount of their current dentifrice. Patients should also be advised to alternate the place in the mouth they begin brushing, so as to limit any one area’s exposure to undiluted dentifrice.¹⁰

ADDRESSING EXISTING WEAR

Often, incorrect brushing technique does not come to our attention until there are already visible signs of tooth wear. By this point, it is quite likely that dentin has become exposed and the patient is at risk for dentin hypersensitivity. Inquire if the patient ever experiences pain when consuming common trigger foods, such as hot and cold beverages. Hygienists and assistants can also ask if the patient avoids specific foods because they cause tooth sensitivity. If the patient is in fact a sensitivity sufferer, a potassium nitrate dentifrice such as Sensodyne ® (GlaxoSmithKline Consumer Healthcare, http://www.gsk.com), Tom’s of Maine Natural Toothpaste for Sensitive Teeth (Colgate-Palmolive Oral Care, http://www.colgateprofessional.com) or Orajel® Sensitive Pain Relieving Toothpaste (Del Pharmaceuticals, http://www.orajel.com) can help reduce the pain.
Some patients who brush incorrectly are often surprised to learn there is a problem. Ironically, it is the extra attention and care they give to keeping their teeth clean that causes the trouble. Hygienists as well as assistants are in an ideal position to identify patients with poor brushing technique, and to help them learn to “Make Brushing Feel Truly Fantastic Again.” Often, the same conscientiousness that leads patients to overzealous brushing can aid in their attention to proper technique. Explain that often all that is necessary is a minor technique adjustment.

Being Proactive About Dentin Hypersensitivity:

YOU CAN’T HELP IF YOU DON’T ASK
Consider the following: It is estimated that 22% of American adults suffer from dentin hypersensitivity, and of these, 42% don’t bring up the issue with their dental professional.¹ Many patients may feel hesitant to talk about the problem because they are unaware that there is often a simple treatment for their pain, or they may fear a more serious condition. Therefore, it is important for dental professionals to proactively question patients about hypersensitivity. Your interest and advice can make a significant difference for patients who have previously suffered in silence.

IDENTIFYING A SUFFERER
Hypersensitivity can affect people at any age, but it is most frequently reported by people between the ages of 20 and 50, particularly those in the 20- to 30-year-old range.² Additionally, women report hypersensitivity more often than men.³ Patients undergoing whitening procedures, either at home or in the office, are at high risk as well; between 55% and 75% of whiteners experience sensitivity.⁴ This wide range of sufferers highlights the importance of asking each patient, particularly whiteners and young women, if they experience tooth pain.

HOW DO YOU ASK?
These questions can help you spark a conversation about hypersensitivity:

Do you avoid specific foods or beverages that cause tooth sensitivity or pain?
Do you experience discomfort from cold, hot, sweet, or sour foods, or beverages?
Have you recently undergone a whitening or bleaching treatment? If so, did you discontinue or interrupt treatment because of tooth sensitivity?
Are you considering using whitening or bleaching treatments in the future?

Sensitivity can occur intermittently, so when questioning patients, inform them that the pain could have been earlier today, yesterday, or last week. Some patients may be able to list foods, beverages, or circumstances that always trigger pain, while others may experience sensitivity seemingly at random. For intermittent sufferers, the unpredictability of the pain can make it just as much a nuisance as it is for regular sufferers.

THE NEXT STEP If a patient’s answers to any of your questions indicate that he or she experiences sensitivity, a review of the patient’s habits may reveal improper brushing techniques or other factors contributing to the pain. You can also perform a clinical examination to exclude secondary causes of dentin hypersensitivity such as dental caries, pulpitis, cracked or chipped tooth syndrome, and/or changes in restorations.
Once any serious problems are ruled out, you can discuss available treatment options with your patient. Commonly used treatments include desensitizing dentifrices, such as Sensodyne® (GlaxoSmith-Kline) to depolarize nerve endings in the tooth, and in-office desensitizing treatments to occlude the tubules. For especially sensitive patients, some practices recommend both treatments; as the in-office treatment brushes off over time, and the dentifrice takes time to build to maximum effectiveness.
Remember that while the triggers, frequency, and severity of dentin hypersensitivity can vary by patient, the most effective way to identify sufferers remains the same: ask.

NON INFECTIOUS HEALTH HAZARDS IN DENTISTRY

2011-09-30T13:08:00.000+03:00

Dental professionals may be at risk for exposure to numerous workplace hazards. There are currently no specific standards for dentistry, but rather workplace hazards that may apply to dentistry are addressed to the entire healthcare industry.¹ However, there are numerous different materials, chemicals, and supplies commonly used in the general dentist’s office that are left out of the expansive collection of workplace hazards.
Concerns arose about the health risks from dental materials since at least the 1960s. The medical literature and government agencies have both examined and made recommendations to reduce risk of miscarriage, birth defects, and reduced female fertility at different levels of exposure to several hazards (materials, chemicals, supplies, radiation, etc).² Fortunately, several steps can be taken to control the level of exposure from these agents, either voluntarily or under the regulations of the Occupational Safety and Health Administration (OSHA). These include, but are not limited to, handling the agents properly, monitoring the levels of exposure, using devices to lower the levels, and properly disposing of the agents.

Mercury
Mercury, the main component in dental amalgam, has been used for more than 150 years in hundreds of millions of patients. Amalgam fillings are composed of a mixture of metal alloys and liquid mercury, with 50% of this mixture being elemental mercury.In 2009, the Food and Drug Administration issued a final ruling that classified dental amalgam as
a class II device (more risk than lower classifications). It was officially stated that dental amalgam releases low levels of elementary mercury vapor. Vapor concentrations are highest immediately after placement and removal of dental amalgam, but decline thereafter.
Elementary mercury (the form used in dental amalgam) is absorbed mainly by inhaling its vapor, which is then distributed throughout the body. Excretion of mercury occurs predominately through the kidneys, and is finally expelled in urine. An examination of the level of mercury in the urine of dentists revealed that dentists had about three times higher levels of urinary mercury than the control subjects. However, finding a measurable amount of mercury in blood or urine does not mean that the level of mercury causes an adverse health effect. In fact, the evidence that mercury vapor may impair female fertility is limited. However, exposure to mercury vapor can be reduced by properly handling dental amalgam.
In 1999, the ADA Council on Scientific Affairs recommended a program to ensure the safety of all dental personnel involved in the handling of mercury or dental amalgam. The ADA recommends against the use of bulk elemental mercury, which is still available for purchase. General precautions include training all personnel that handle dental amalgam of the potential hazards of mercury vapor and observing good mercury hygiene practices. Poor handling of dental amalgam and the exposure to the vapor in the operating areas can be limited.

Dental offices using amalgam are required to have a mercury spill kit available. The specific type and number of spill kits that the facility must make available is based on the information on the chemical’s MSDS. Mercury spill kits are available from both Patterson Dental Supply and Henry Schein.
It is further recommended to periodically check the dental operatory atmosphere for mercury vapor. Dosimeter badges and mercury vapor analyzers are available. The dosimeter badges monitor the specific amounts of mercury levels to the specific individual wearing the badge.
The OSHA standard for mercury is 0.1 mg per cubic meter of air averaged over an 8-hour work shift. The National Institute for Occupational Safety and Health (NIOSH) has recommended the permissible exposure limit to be changed to 0.05 mg/m³ averaged over an 8-hour work shift over a 40-hour workweek.
Exposure to mercury vapor may involve some risk for birth defects; however, the results are limited. Most studies on this topic have been retrospective in nature and, naturally, many variables, such as other health conditions, smoking, drug use, physical strain, and age, were difficult to discern. On the other hand, there are no reported strong associations of miscarriage or fetal death due to the levels of mercury used in the dental office.

Nitrous Oxide
Nitrous oxide (N²O), commonly called laughing gas, is an anesthetic agent. Workers are exposed to N²O while administering the anesthetic gas to patients. Scavenging systems that vent unused and exhaled gas away from the work area help to protect workers from the health risks associated with N²O . Research has shown that these systems can significantly reduce the risk of impaired fertility among female dental assistants exposed to N²O.The NIOSH has suggested an occupational exposure limit (OEL) of 25 parts per million (ppm) for the duration of exposure as a time-weighted average (TWA), while the American Conference of Governmental Industrial Hygienists (ACGIH) has assigned a threshold limit value (TLV) of 50 ppm as a TWA for a normal 8-hour workday/40-hour workweek. Without a scavenger in place, concentrations of N²O were routinely reported as 1,000 ppm to 2,000 ppm in the dental operatory or 40 times or more exposure than the suggested exposure limit.Alarmingly, a NIOSH Alert reports that even with scavenging systems in place, researchers measured exposures more than 1,000 ppm than the NIOSH-recommended limit in dental operating rooms. This indicates that even with a scavenging system in place, the exposure to higher levels of N²O is possible. Using a scavenger system is not sufficient unless it is continuously monitored and maintained to effectively reduce exposure to N²O.
In addition, the Centers for Disease Control and Prevention (CDC) has issued a hazard statement on the control of N²O in the dental operatory. This report states that N²O exposures should be minimized to prevent short-term behavioral and long-term reproductive health effects. Epidemiological studies conducted mostly on operating room personnel (who are possibly the nearest comparison in the literature to dental assistant personnel) have shown increased risks of spontaneous abortion, premature delivery, and involuntary infertility among those occupationally exposed.
There are three systems that can be used to reduce N²O concentrations to approximately 25 ppm (the maximum level of exposure recommended by NIOSH) during clinical use in the dental operatory:

System maintenance should be done by inspecting and maintaining the anesthetic delivery system to prevent N²O leaks in all hoses, connections, and fittings—leaks must be repaired immediately.
Ventilation should be accomplished by the use of a scavenging system with an air flow rate from the patient’s mask at 45 LPM, measured by a calibrated flow device and then vented outdoors. The operatory, where possible, should use 100% clean outdoor air for ventilation. Finally, a local exhaust hood should be placed near the patient’s mouth to capture excess N²O.
The proper-sized scavenging mask must be used on the patient. In addition, only the minimum amount of N²O needed should be used. Finally, the air concentration of N²O must be monitored to ensure the above controls are effective in achieving low levels of N²O in the dental operatory.

NIOSH recommends air sampling for N²O periodically. A diffusive sampler is easily available from dental supply companies and various manufacturers. The diffusive samplers are easy to use and inexpensive. It can be used to measure a dental worker’s exposure by attaching it to the lapel (breathing zone) and uncapping/recapping it during N²O use. Manufacturer’s directions should be followed to have the results interpreted.

Radiation
All dental workers must follow precautions to prevent exposure to radiation emitted from dental x-ray machines.¹⁷ All workers, especially pregnant workers, should consider wearing a monitoring dosimeter film badge on uniforms. DHCW must stand at least 6 feet away from an x-ray machine or behind a lead-lined wall, and should never attempt to hold film in a patient’s mouth during x-ray exposure.¹⁷
Another precaution that may help limit exposure is ensuring the machines are properly collimated. Workers should never be in the room or in the path of the active beam. Settings should include the proper kVP and MA. Also, the highest speed film to reduce the radiation needed to expose the film should be used.^17-20
The dose for total body exposure is measured as a level of rem (a person’s risk that he or she will suffer health effects from an exposure of radiation). The level of exposure from one dental x-ray is 0.004 rem to 0.015 rem. Digital imaging using a sensor rather than film may offer reduced radiation exposure compared to film. Three-dimensional imaging with cone beam computed tomography (CBCT) is being used with increasing frequency in dentistry. The radiation dosage in a CBCT can be anywhere between 4 and 42 times higher than a comparable panoramic radiograph.^18-20
The permissible dosage for the total body is 5 rem per year, or no more than 3 rem permitted within a 13-week period. An exposure equivalent to 5 rem per year is believed to permit a lifetime occupational exposure without reaching an injurious level. In addition, the dose limit for the fetus of an occupationally exposed woman is 0.5 rem for the entire gestation period. Prenatal radiation exposure may result in prenatal death. Doses of 10 rem to 19 rem received by human fetuses have been shown to produce small head size, whereas doses above 150 rem have been associated with mental retardation.

Bisphenol A
Dental sealants and composite filling materials contain bisphenol A (BPA) derivatives. These materials are increasingly being used in childhood dentistry. Recent news has focused on the dangers of bisphenol A and related compounds in dental materials. Although continued use (with strict adherence to precautionary application techniques) is recommended, the use of these materials should be minimized during pregnancy. It appears that BPA levels in the saliva peak over a 3-hour period following sealant placement and returned to baseline within 24 hours. To reduce the potential risk for BPA toxicity from sealants, a mild abrasive (such as pumice, either on a cotton applicator or in a prophy cup) should be used after the restoration is complete. In addition, the provider can wash the sealant surface for 30 seconds with an air-water syringe while suctioning fluids from the mouth. In the long term, manufacturers should be encouraged to develop materials with fewer effects on the reproductive system (specifically, less estrogenic potential).
Other Agents
In the literature, concerns about the reproductive risks associated with occupational exposure to other agents exist. The most common warning of a chemical’s presence is its odor. However, people cannot detect odors equally well and not all chemicals with a strong smell are harmful to the fetus. Therefore, odor should not be relied upon to warn of the presence of a hazard, but it can indicate the presence of a chemical. The CDC has listed several chemicals in dentistry and other fields of healthcare that may be hazardous to reproduction. Most of the risks can be reduced with appropriate protective clothing, such as gloves and face shields. Splash-proof safety goggles should also be provided and required for use.

Conclusion

The authorities on occupational health cannot provide specific medical advice concerning potential risk factors for those currently pregnant or trying to become pregnant. Workers should consult with their primary care physician and/or an obstetrician for medical advice and recommendations. Before working with any chemical, the manufacturer’s instructions should be read and followed. It is also important to refer the material safety data sheets (MSDS) for more information. Workers should ensure that they have received all recommended immunizations and consult with their personal physician regarding which immunizations may require booster doses.
As mentioned, many of the results from the studies are retrospective in nature, which allows many variables to cast uncertainty on the results obtained. Due to the variety of agents and the lack of research, the increased risk of reproductive hazards cannot be excluded for all dental materials. Additionally, there is not enough evidence in human trials to determine whether or not these dental materials will have an adverse effect on female fertility or pregnancy.

DISINFECTING CLINICAL SURFACES

2011-09-29T15:09:00.000+03:00

Dental operatory surfaces and equipment can become contaminated with patients’ blood and other oral fluids through contact with dental healthcare personnel’s (DHCP) gloved hands; spray and splash created by dental instruments such as handpieces, air/water syringes, and ultrasonic scalers; and through contact with contaminated instruments placed on various surfaces. Determining the management of environmental surfaces in the dental setting requires attention to the areas and objects that may become contaminated during patient treatment and classification of disinfectants and surfaces to guide DHCP in proper technique and materials for disinfection.

Classification of Disinfectants

E.H. Spaulding, a pioneer in healthcare disinfection and sterilization, identified three classifications of disinfectants, based on the product’s ability to kill certain organisms.¹ High-level disinfectants are capable of killing all microorganisms, including resistant
bacterial spores. High-level disinfectants, such as glutaraldehyde and hydrogen peroxide-based products, are not appropriate for use on environmental surfaces and dental equipment; these products are intended for immersion disinfection or sterilization of heat-sensitive instruments.
Intermediate-level disinfectants are not necessarily capable of killing spores, but will inactivate Mycobacterium tuberculosis var. bovis, which is considerably more difficult to kill than vegetative bacteria. These intermediate-level disinfectants will also kill fungi and all types of viruses.
Low-level disinfectants will not reliably inactivate spores, mycobacteria, all fungi, and all viruses.²Some disinfectants have active ingredients that at one concentration will be categorized as intermediate-level and at a different concentration will be classified as low-level. Careful review of the manufacturer’s label of a product will provide the necessary information to select among the three classifications of disinfectants and the proper dilution and use of the product.

Classification of Environmental Surfaces

Environmental surfaces carry a lower risk of disease transmission than do instruments and devices that come into direct contact with patients.² Surfaces in the dental operatory can be divided into two broad categories for purposes of determining the level of decontamination indicated: medical equipment surfaces and housekeeping surfaces.³ Oral healthcare settings differ from most other healthcare settings in that DHCP often use aerosol and spray-producing equipment such as handpieces, ultrasonic scalers, air/water syringes, and other devices. The spray from these devices can contain blood that then settles on the surfaces and equipment in the area around the patient’s head.^4,5 The medical equipment surfaces, which are also called clinical contact surfaces,⁶ must be decontaminated between patients to avoid inadvertent cross-contamination. Some examples of surfaces that may be considered clinical contact surfaces include dental radiographic equipment, knobs, switches, light handles, drawer handles, chairside computers, countertops, nitrous oxide equipment, and digital impression devices, among others. For all of the clinical contact surfaces, barriers that are impervious to fluids are an acceptable alternative to disinfection Figure 1. When using barriers, change them between each patient and carefully place and remove them in a manner that does not cause contamination of the protected surface or the DHCP’s hands. Used barriers should only be handled while wearing gloves.

Figure 1 Barriers may be used as an alternative to disinfection on clinical contact surfaces

Housekeeping surfaces have the least potential for cross-contamination, and therefore require less stringent procedures than clinical contact surfaces. Examples of housekeeping surfaces include floors, walls, sinks, windowsills, and other areas within the dental operatory that are not directly contacted by DHCP and patients during patient treatment. Housekeeping surfaces should be cleaned on a regular basis using soap and water. Studies in hospital settings showed no difference in healthcare-associated infection rates when disinfectants were used instead of soap and water to clean floors. If there is uncertainty regarding the nature of contamination—or there is overt blood present on the surface—an EPA-registered hospital disinfectant should be used when cleaning floors. Because studies regarding housekeeping surfaces are relatively small and lack strong statistical significance, some recommendations conclude that either detergent and water or a disinfectant is indicated for floors in healthcare settings.The judgment in this area should be based on the level of contamination and the likelihood of transferring contamination from the floor surface to the patient. Unless contamination is suspected, vertical surfaces such as walls do not require routine cleaning and disinfecting.

Regulations

Two agencies within the US government regulate the manufacture of disinfectants used in healthcare settings. The Environmental Protection Agency (EPA) regulates disinfectants for use on environmental surfaces. The Food and Drug Administration (FDA) regulates the manufacture of liquid chemical sterilants and high-level disinfectants. Liquid chemical sterilants/high-level disinfectants are not appropriate for use on environmental surfaces and should be used for immersion of heat-sensitive items only. Products registered with the EPA are classified as hospital-level disinfectants and carry the EPA registration number on the label (Figure 2). All claims for germicidal activity must be reviewed by the EPA and supported through testing by the manufacturer. The EPA does not recognize the distinction between low- and intermediate-level disinfectants in its registration procedures, so this will not be reflected on the EPA registration label. The way to determine if a product is intermediate-level is by whether it has a claim as a tuberculocidal disinfectant on the product label. Disinfectants that are EPA-registered as a hospital-level disinfectant, but do not kill tubercle bacillus, are categorized as low-level disinfectants.
The Occupational Safety and Health Administration (OSHA) also regulates the use of disinfectants as they relate to healthcare in the Bloodborne Pathogens Rule. OSHA requires that contaminated work surfaces be decontaminated at the end of procedures, after blood spills, as soon as feasible after becoming overtly contaminated, and then at the end of the work shift if contamination has occurred since the last decontamination. OSHA does not specify the type or level of disinfection, but it does indicate that impervious barriers are an acceptable alternative to chemical disinfection.

Disinfectants

Simply applying a disinfectant to a clinical contact surface will not reliably decontaminate the surface. A number of factors influence the effectiveness of the disinfectant and the disinfecting process. The number and location of the microorganisms is significant, because there is a relationship between the total number of organisms and the time needed for complete destruction. Cleaning surfaces before applying disinfectant solution will reduce the total microbial contamination, reducing the amount of time needed for germicides to work Figure 3. In addition, clumped cells are more difficult to inactivate, and the physical activity of cleaning a surface helps disrupt potential clusters or clumps of debris containing microbes.
Other factors that can influence the effectiveness of disinfectants include dilution, temperature, pH, relative humidity, and water hardness. Organic debris, such as blood, tissue, or lubricant material, can interfere with the efficacy of disinfectants either by chemical reaction between the material and the germicide or by the organic material’s acting as a physical barrier that protects microorganisms.
The time needed for disinfectants to kill the organisms listed on the label is provided by the manufacturer, and DHCP performing disinfection procedures should ensure that the surfaces remain wet for the time indicated to ensure complete disinfection. Do not include the time needed to preclean the surface in the disinfection time. Therefore, the CDC recommends the use of products with short contact times (1 to 3 minutes) rather than disinfectants that require longer contact times (10 minutes).

Figure 3 Cleaning surfaces before applying disinfectants is a critical step in the decontamination of clinical contact surfaces

Disinfecting Procedures

Disinfectants may be delivered as either a spray or a wipe to clinical contact surfaces. In either case, the procedure is the same. The surfaces should be sprayed, then wiped, or they should be wiped with disinfectant-soaked towelettes, to remove debris. After the cleaning step, the surface should be sprayed again, or wiped with disinfectant towelettes and allowed to remain wet for the time indicated on the product label. A fresh wipe should be used for each of the cleaning and disinfecting steps. There is some indication that the improper use of wipes (ie, the use of one wipe on multiple surfaces) may result in the cross-contamination of surfaces in the patient environment.

Conclusion

The management of clinical contact surfaces remains an important aspect of an infection control program for all oral healthcare settings. Understanding the proper use and selection of disinfectants and barriers helps ensure a safe patient environment. Disinfectant products are sensitive to a number of factors that can affect their potency; therefore, DHCP using these products should receive appropriate training and should always reference the manufacturer’s directions for use, dilution, and shelf life.

Oral Malodor: Causes, Assessment, and Treatment

2011-09-28T18:08:00.000+03:00

Oral malodor has been recognized in the literature since ancient times. However, in the last 5 to 6 years, it has come to the forefront of public and dental professional awareness. Oral malodor is caused mainly by facultative bacteria on the tongue that produce volatile organic compounds. Traditional assessment methods include organoleptic measurements and gas chromatography. Newer techniques make diagnosis more convenient, and the electronic nose is in the early stages of development. After assessment, active practices of using proper oral hygiene products and making small lifestyle changes can reduce the amount of oral malodor significantly for an individual. Understanding causes, assessment, and treatment of oral malodor can help dental professionals find ways to decrease its prevalence and increase their patients’ well-being.
More than 50% of the general population has oral malodor,¹ commonly known as “bad breath.” Present-day research has shown sulfur-producing anaerobic bacteria on the tongue form certain volatile organic compounds (VOCs) that produce unpleasant odors in the mouth. Numerous methods are used for assessing oral malodor severity. Traditional oral malodor assessment methods include organoleptic measurements and gas chromatography, while advanced technology has given rise to machines that make diagnosing oral malodor in dental clinics more convenient.
Diagnosis is only the first step in treatment. On consultation by dental professionals, patients must take further action to control and manage oral malodor in their daily lives. They can accomplish this either mechanically or chemically. Each case is treated differently, depending on its origin. By having a holistic grasp of where oral malodor originates and how to analyze and treat it, future dental products can be made to better cater to these patients. The consequences of having oral malodor are twofold. Oral malodor not only makes the individual feel uncomfortable in public places but also can be an indication of the individual’s overall well-being. Thus, careful analysis of oral malodor can be used as an approach in diagnosing systemic diseases and understanding how lifestyle habits affect oral health.

Oral and Non-Oral Causes

Oral malodor can be grouped into two categories: non-pathologic and pathologic, or chronic oral malodor. Non-pathologic oral malodor is temporary and caused by normal metabolic functions in the body. Causes may include the lack of proper salivary flow during sleep, hunger, food debris, smoking, and the use of prescription drugs.¹ Substances absorbed into the circulatory system may be released in pulmonary air or saliva as volatile odoriferous compounds derived from foods.
Pathologic, or chronic oral malodor, can originate from oral causes, which are much more common than non-oral causes. Oral factors include poor dental hygiene, food particles in the teeth, periodontal disease, coating on the tongue, wearing dentures overnight, dry mouth, and defective restorations. Mucositis induced by radiation therapy exposure also could cause oral malodor. Other oral causes include Sjögren’s syndrome, peritonsillar abscess, cleft lip or palate, cancer of the pharynx, and cryptic tonsils.¹
Pathologic oral malodor also can originate from non-oral causes, which include diabetic ketosis and acidosis; uremia; erratic bowel movement and regurgitations; hepatic and renal failure; and certain types of cancer, such as leukemia. Although select patients with a history of gastrointestinal diseases have experienced oral malodor, it has not been determined whether gastrointestinal diseases actually cause oral malodor. Furthermore, a few deviant physiologic processes, such as enzymatic and transport abnormalities (eg, trimethylaminuria), also may initiate oral malodor.

Saliva
Saliva plays a central role in the formation of oral malodor. One of the functions of saliva is to purge any remaining food debris from the oral cavity. Periodontal pockets can cause food debris to accumulate and the rate of foul-odor production to increase.² Some medications may cause xerostomia and result in oral malodor, especially those with anticholinergic activity. Such medications include antihistamines (eg, astemizole, brompheniramine), tricyclic antidepressants (eg, amitriptyline, desipramine), diuretics (eg, chlorothiazide, furosemide), antihypertensives (eg, captopril, clonidine), and analgesics (eg, codeine, meperidine) (Table 1 A and B).³ Sympatholytics also can cause xerostomia. They include α-blockers (eg, terazosin), α-2 agonists (eg, clonidine), and ß-blockers (eg, metoprolol).⁴ Oxazepam, which is a muscle relaxant and sedative, has side effects that include xerostomia; however, this is temporary.
By studying incubated saliva, researchers can help determine how oral malodor and other oral developments are formed through the interaction of microbial flora in the mouth. Whole saliva is centrifuged and incubated in an aerobic environment. The incubation gives rise to a salivary sediment malodor system that represents the formation of oral malodor.

The Tongue Plaque Coating
Through research,⁷ VOCs have been found to be the primary culprit of engendering oral malodor. VOCs are gaseous substances that are produced primarily on the tongue and contain volatile sulfur compounds (VSCs) hydrogen sulfide (H₂S), dimethyl sulfide ([CH₃]₂S), methyl mercaptan (CH₃SH), and sulfur dioxide (SO₂). Oral malodor is created primarily on the tongue, with the VSCs made on the lingual dorsum. The bacteria that produce these VSCs can be found by evaluating biofilm and scraped specimens from the lingual dorsum, gingival pockets, and tonsillar crypts.⁷ VSCs are produced by gram-negative anaerobic bacteria that live on the lingual dorsum.⁸ These bacteria can thrive on the tongue because food debris accumulates rapidly on the tongue’s large surface area and papillae.
In a study by Tyrell et al,⁹ tongue samples were cultured and numerous bacterial species isolated. Among those isolated, the most common were Peptostreptococcus anaerobius, Collinsella aerofaciens, Eubacteriumgroup, Actinomyces species, Eikenella corrodens, Veillonella species, Fusobacterium nucleatum, pigmentedPrevotella species, and Selenomonas species. Other bacteria frequently found on the lingual dorsum wereTreponema denticola, Porphyromonas gingivalis, Peptostreptococcus micros, Actinomyces israelli,Selenomonas flueggei, and Proteus mirabilis (Table2). Tongue cleaning improves taste sensation and seems to reduce the substrata for putrefaction, rather than the bacterial load.¹⁰ The tongue coating consists of blood components, nutrients, epithelial cells, and bacteria. The amount of VSCs on the tongue is correlated with the amount of tongue coating. In addition to the VSCs, the presence of tongue coating may be related to the level of secretory immunoglobulin A (IgA) in the saliva. In patients who have only slight tongue coating, the concentration of secretory IgA was found to be higher than in patients with moderate-to-heavy coating. Combined with findings on Streptococcus species, secretory IgA may act as shielded protection against tongue plaque.

Hess et al¹² proposed a mathematical model to determine oral malodor formation. It describes the structure of the biofilm, transfer of oxygen, flow of substrates, and formation of VSCs, which are all part of the oral malodor process. According to this model, each papilla is a cluster of strands protruding perpendicularly from the tongue. The biofilm covers the core tissue of the papillae. The deeper layer of the biofilm is assumed to be anaerobic, while the superficial layer of the biofilm is considered aerobic. The biofilm metabolizes oxygen gradually. The only part of the papilla that is oxygenated is the upper tip, so aerobic bacteria can grow. Substrates can enter from above or below the biofilm. All of the substrates are converted to VSCs via a chain process. However, substrates that enter from above the biofilm are transient and soon depleted, while permanent substrates entering from below the biofilm become the source of oral malodor. VSCs leave the biofilm via four transport mechanisms: diffusion, conversion, salivary flow, and volatilization.

Microbiota-Associated Oral Malodor
Research has shown antibacterial agents can reduce oral malodor, supporting the idea that oral malodor has a bacterial origin.⁷ Gram-negative bacteria are the primary source of the malodor; however, gram-positive oral microorganisms play the initial role of producing such odors by facilitating proteolysis of certain amino acids pertinent to odor production. Although it was previously thought that gram-positive bacteria did not play a role in oral malodor, recent research has shown when antibacterial agents were used on gram-positive bacteria, mainly streptococci, there was a reduction in oral malodor in an in vitro model. Gram-positive bacteria species, such as Streptococcus salivarius deglycosylates (salivary glycoproteins), expose their protein core to be further degraded by gram-negative bacteria.⁷ Gram-negative bacteria produce odors in the presence of three amino acids. Reduction of methionine to methyl mercaptan and cysteine leads to the reduction of cysteine to cystine, which produces hydrogen sulfide when sulfhydrase-positive microbes are present.^1,7Recent research has shown VOCs, mainly alkanes or alkane derivatives played a significant role in oral malodor. These compounds are produced from high oxidative stress, which can be an indication of periodontal infection in the oral cavity. The VOCs, such as VSCs, are considered the most influential components of oral malodor.

Oral Malodor Assessment Parameters

Organoleptic Measurements
Organoleptic measurements are considered to be the gold standard for measuring and assessing bad breath,¹⁴ which can be quantified based on the intensity of the odor and offensiveness. Organopleptic judges are trained before rating the subjects, using a four-phase training protocol based on the American Society of Testing and Materials standards. First, the organoleptic judges are introduced to the scales and sniffing techniques. Then, they perform exercises that consist of smelling pleasant, neutral, and unpleasant odors; identifying the odorant; and discriminating the odors from similar ones. Finally, the judges are assessed on how well they are trained, based on a post-test in which the same odorants used in pre-training were placed in a different order.¹⁵ There are gender and age differences in the judges’ performances, in which women have better performance and older individuals have lower performance.1 These judges independently rate the intensity of the odor in participants by the Rosenberg scale from 0 to 5, which is as follows: 0 = no odor; 1 = barely noticeable odor; 2 = slight but clearly noticeable odor; 3 = moderate odor; 4 = strong offensive odor; and 5 = extremely foul odor; with a score ≥ 2 equaling halitosis.^1,15,16 The offensiveness of the odor is measured on a hedonic scale in which a score of +2 = like very much; +1 = like; 0 = do not like or dislike; -1 = dislike; and -2 = dislike very much.¹⁵ Many other hedonic scales are available with differing intensity ranges that are used in studies of oral malodor, with some scales being more common than others. Participants are asked to refrain from eating, using dental products, and/or wearing any type of perfume for 4 hours before the visits because these actions may affect the results.^1,16
Portable Sulfide Meter
A portable sulfide meter has been used to test oral malodor because of its reproducibility and ease of use.^1,16Before the examination, participants are to refrain from all oral-related activities and wearing of fragrances that may influence the results, based on the sensitivity of the machine. They are asked to exhale for 30 seconds through a tube connected to the machine. The sulfide meter records a score based on VSC levels in parts per billion (ppb) based on electrochemic and voltametric sensors. There are three categories of scores: Normal = 80 ppb to 160 ppb; Weak = 160 ppb to 250 ppb; and Strong = > 250 ppb. “Weak” signifies malodor at a close distance, and “Strong” signifies malodor at a greater distance.¹⁶ This method is repeated three times, and the mean of the scores is taken.^1,16 However, one major disadvantage of using this instrument is that it does not differentiate the various sulfide-containing compounds; for example, CH₃SH is three times more unpleasant than H₂S.^1,2 Because of this limitation, the sulfide meter may underestimate oral malodor in patients who have higher CH3SH concentrations.²
Gas Chromatography
Gas chromatography (GC) is a highly reliable, objective, and reproducible technique for detecting oral malodor.¹⁴ GC measures the amount and type of specific VSC and VOCs in the mouth air. Samples of oral cavity breath are collected in a multi-laminate bag. The VOCs are extracted from breath samples onto sorbant traps. GC uses a flame photometric detector to analyze the odors. VOCs are identified by computer-based libraries and quantified by their amounts compared with an internal standard. Background VOC contaminants are quantified by inflating the sample bags with helium and subtracted from the VOCs in the breath.¹³Although extremely precise, this method is not used commonly in chairside clinical settings because it takes a long time to run, is expensive, and requires a skilled operator.^14,17 This method of measurement is particularly useful if the sample population is small.¹⁷
Portable Gas Chromatography
A portable GC device can be used to measure the VSCs in the breath¹⁸ and can identify oral malodor’s three causal components, which are hydrogen sulfide, methyl mercaptan, and dimethyl sulfide. The device also gives precise measurements of the concentrations of the compounds. To measure these concentrations in patients, a syringe (without the needle) is placed deep into the oral cavity. Then, the plunger is slowly withdrawn, inserted, and withdrawn again before the syringe is removed from the mouth. Then, the sample is injected into the machine where measurements start automatically. The benefits are its cost-effectiveness and convenience and is less time-consuming than traditional GC methods and, therefore, could be used readily in an office.¹⁸
Electronic Nose
The electronic nose is a handheld instrument that has the ability to “smell” and produce unique fingerprints for odors.¹ One odor discrimination analyzer (electronic nose) has a chemical sensor system that uses six metal oxide semiconductor sensors for odor discrimination.^1,19 Each sensor has to be selected based on the sensitivity and fragrance of the odorant being tested because of various pattern recognition software. To use an electronic nose, the mouth-air gas from a patient is first trapped in a tube for 30 seconds and then driven up a sensor section with pure nitrogen. An estimated VSC concentration and organoleptic score is calculated.¹⁹ This instrument has made odor analysis fast and simple and also is fairly cost-effective. Although the electronic nose has been used throughout the medical fields, few studies have been done to assess its effectiveness in clinically assessing oral malodor.

Oral Malodor Management

For the general case of non-systemic oral malodor, treatment often begins with proper oral hygiene at home, in which the patient must brush, floss, and tongue scrape properly and regularly. These procedures will reduce the amount of VOCs and microorganisms in the mouth.²⁰ Specifically, much emphasis has been placed on tongue cleaning to reduce the amount of coating on the back of the tongue. A recent study examined how different tongue-cleaning methods affected bacteria on the dorsal surface of the tongue for 4 days.²¹ After accessing 19 patients, researchers determined the most significant reductions in gram-negative bacteria were seen when toothbrushing was followed by tongue cleaning using a high-speed vacuum ejector and irrigating with mouthwash; this was the most inclusive of the procedures. Toothbrushing and tongue scraping was next in reducing tongue microflora, and toothbrushing alone demonstrated the least reduction.²¹However, tongue scraping was shown to have a prolonged effect even on Day 4, whereas the other two mechanisms had temporary effects only. Thus, regular tongue cleaning is essential for providing long-lasting or overnight hindrance of bacterial formation.²¹ Because patients usually neglect tongue cleaning in daily oral hygiene as a result of discomfort or lack of familiarity with the practice, professionals should demonstrate the appropriate use of tongue scrapers.¹ Then, patients can perform the action at home comfortably and effectively. Patients should start scraping as far back as possible to remove the most debris. Often, first-time tongue-scrapers will experience a gag reflex; however, they should be informed that this will subside eventually as they continue daily tongue cleaning. Tongue scrapers come in a wide variety: flexible metals or plastics, blunt flat edges or serrations, manual or electric, etc. Some are in vertical form, in which a handle and scraper are on the end. Patients should seek a scraper according to their preferences and needs.
In addition to mechanical means, products with antimicrobial components should be recommended to patients for use at home, such as mouthwashes containing cetylpyridinium chloride, chlorhexidine, triclosan, quaternary ammonium compounds, benzalkonium chloride hydrogen peroxide, sodium bicarbonate, zinc salts, or essential oils.¹ These mouthwashes are formulated based on scientific evidence that they target microbiota on the tongue while maintaining the natural internal balance of the mouth.¹ Such products may either reduce the concentration of VOCs and odor-causing microbes or act as oxidizing agents1 to neutralize the pH of the mouth to prevent growth of unwanted bacteria.²⁰ Professional advice must be given as to the administration, caution, and type of oral product to be used.¹ As of now, only chlorhexidine mouthrinses are administered clinically to patients with a prescription. For the most part, the public has turned to commercially available, over-the-counter mouthwashes that have deodorant-type properties to mask oral malodor instead of having antiseptic purposes. If a mouthwash’s antibacterial function comes from alcohol, which also enhances the flavor of the mouthwash, a slight dry-mouth effect may occur.
Triclosan is an antibacterial agent commonly found in many anti-acne products, hand soaps, and detergents. For many years, triclosan has been included in the toothpaste formulations to enhance inhibitory effects on bacterial metabolism in dental plaque. Numerous studies have confirmed these effects by showing a reduction in the accumulation of dental plaque, gingivitis, and calculus. One study revealed brushing twice a day with a triclosan toothpaste with or without tongue scraping significantly reduced the amount of bad breath caused bacteria.²² The triclosan-containing toothpaste was compared against the control, a standard sodium fluoride toothpaste. Using a Halimeter^® (Interscan, www.halimeter.com) to measure the VSC concentrations, a reduction by more than 20 ppb was observed when measurements were taken at 3, 24, and 27 hours for 2 days.²² After using the triclosan toothpaste, participants reported in a questionnaire that their mouths overall felt “fresh and clean.” This demonstrates a simple regimen coupled with a triclosan-containing product can have profound effects against bad breath. Conversely, triclosan, essential oils, and cetylpyridinium chloride are still less effective in comparison to chlorhexidine for short-term management of oral malodor.²³ The effectiveness of active ingredients in oral healthcare products depends on their concentration, in which excessively high concentrations can leave unpleasant side effects. Triclosan is not as potent as many other dentrifice compounds but nonetheless has anti-gingivitis and anti-plaque properties when used with other products that may contain stannous fluoride, chlorhexidine, essential oils, cetylpyridinium chloride, etc.²⁴Clinical studies have suggested the continued use of dentifrices and mouthwashes containing triclosan because these products amplify the effects of mechanical brushing and flossing to combat bad breath caused by bacteria.² Other recent studies have shown the effectiveness of stannous fluoride in toothpastes for combating oral malodor.²⁶ As a chemotherapeutic agent, stannous fluoride has wide-spectrum antimicrobial properties against both gram-positive and gram-negative species. Numerous clinical trials have demonstrated how well stannous fluoride acts against caries, plaque, gingivitis, and bad breath. These benefits are because of the multifaceted mechanisms of the stannous ion, from the alteration of bacterial growth to the inhibition of bacterial adhesion with the tooth surface to the inhibition of bacterial carbohydrate metabolism and enzymatic catalysis. Recently, a study attempted to evaluate the effect of 3 weeks’ use of a 0.454% stannous fluoride dentifrice on oral malodor, comparing it with a traditional 0.243% sodium fluoride dentifrice (the control). One of the two products was assigned randomly and blindly distributed to each of the 71 patients. Patients were asked to brush with their assigned products for 60 seconds twice a day for 3 weeks, and oral malodor was assessed on a 9-point hedonic scale²⁶ as seen in Figure 1. The stannous fluoride dentifrice provided significantly lower mean hedonic scores than the control dentifrice at both Week 1 and Week 3,²⁰ shown in Figure 2. These results suggested stannous fluoride provided a sustained significant improvement in oral malodor relative to a control dentifrice.
1
2

If the oral malodor is caused by periodontitis, traditional scaling and root planing in the dental office may alleviate the depth of the periodontal pockets and severity of gingival inflammation. As a result, plaque elimination correlates with fewer odor-causing bacteria of the mouth. Treating malodor caused by periodontitis requires a careful initial evaluation and diagnostic plan,such as the one shown in Figure 3. Chlorhexidine can be administered to ease gingivitis and plaque buildup in patients with gingival disease.However, extended use of the product should be avoided because the rinse can discolor the teeth and tongue eventually. Overusing the product could cause resistance of certain bacteria to the formula and, therefore, lower its efficacy.Rather than for the main intention of treating oral malodor, chlorhexidine primarily is prescribed to cleanse underneath the gingiva of patients who have periodontitis. In turn, the rinse also relieves the mouth of foul odor after expulsing the accumulated bacteria. Patients may be advised to use oral irrigation systems with a chlorine dioxide mouthrinse to reach between teeth and under the gingiva; subgingival irrigation tips can be used if the pockets are deeper than 4 mm to 4.5 mm. An antimicrobial gel can be used to brush the gingiva, cheeks, and roof of the mouth, which should be left on without rinsing. Just as with all patients, providing oral hygiene education is a necessity for successful treatment of periodontal disease.
Aside from the hygiene aspect, patients also can chew fibrous vegetables and sugarless gum to increase saliva flow and, in turn, help decrease oral malodor.Saliva functions as a buffering and cleaning agent that keeps bacteria at a manageable level in the mouth.Lastly, patients with oral malodor are encouraged to reduce or stop smoking, avoid offending foods, and eat at irregular intervals.

Conclusion

Assessing oral malodor vigilantly from the beginning will enable dental professionals to treat each case appropriately. Sometimes the origins of the odors may stem from systemic diseases or side effects of certain drugs, and so these instances cannot be treated superficially. Then, the patient must be referred to a physician for further treatment based on the underlying causes. Other times, a patient who may not have true oral malodor insists he or she has it. Such patients with halitophobia should be referred to a psychologist for treatment. Through increasing investigation of this common concern, clinicians will one day be able to perform noninvasive procedures for diagnosing diseases by assessing differing odors, while more innovative products can help patients with oral malodor live comfortably and with self-confidence.

References

1. Nachnani S. The effects of oral rinses on halitosis. J Calif Dent Assoc. 1997;25(2)145-150.
2. Klokkevold PR. Oral malodor: a periodontal perspective. J Calif Dent Assoc. 1997;25(2):153-159.
3. Guggenheimer J, Moore P. Xerostomia: etiology, recognition and treatment. J Am Dent Assoc. 2003;134(1):61-69.
4. Reisfield GM, Rosielle DA, Wilson GR. Xerostomia. 2nd ed. Fast Facts and Concepts. December 2008; 182.
5. Cochran S. Serax (oxazepam) causes xerostomia/dry mouth/cotton mouth. Associated Content. December 2008.
6. Hu Y, Hu DY, Zheng LL, et al. Establishment of malodor model and its effects on identifying the halitosis-related bacteria. Hua Xi Kou Qiang Yi Xue Za Zhi. 2007;25(3):226-229.
7. Krespi YP, Shrime MG, Kacker A. The relationship between oral malodor and volatile sulfur compound-producing bacteria. Otolaryngol Head Neck Surg. 2006;135(5):671-676.
8. Sterer N, Rosenberg M. Streptococcus salivarius promotes mucin putrefaction and malodor production by Porphyromonas gingivalis. J Dent Res. 2006;85(10):910-914.
9. Tyrrell KL, Citron DM, Warren YA, et al. Anaerobic bacteria cultured from the tongue dorsum of subjects with oral malodor. Anaerobe. 2003;9(5):243-246.

Prescribing Recommendations for the Treatment of Acute Pain in Dentistry

2011-09-28T06:27:00.001+03:00

Effective acute pain management is an essential but sometimes challenging component of dental practice. Numerous studies have examined the efficacy of various analgesic agents in dental postoperative models. This article combines an evaluation of the available evidence with current prescribing patterns to provide dental practitioners prescribing recommendations for acute pain, based on the anticipated severity of post-procedural pain. An important consideration when prescribing analgesics is to determine for whom opioid analgesics are necessary and appropriate, and if so, the dose and quantity that should be prescribed. This is partly because of the prevalence of substance and alcohol abuse that can be expected to be encountered within the dental patient population, and because substance abusers in the community frequently obtain prescription drugs from friends and family for misuse.
A number of dental procedures cause acute post-procedural pain, making effective pain management for all patients an essential component of dental practice.¹ Achieving adequate and safe pain relief may be more challenging in some patient populations, such as those with substance abuse or chronic pain disorders.^2,3However, pain following certain dental procedures can be anticipated, which provides dentists an opportunity to thoughtfully plan and optimize the management of acute pain.

Overview of Evidence for Analgesic Use in Dental Pain

Postoperative pain following the surgical removal of impacted third molars is a frequently used analgesic model because of the consistency and intensity of the postoperative pain.^4-6 This common procedure is performed under local anesthesia, usually with concomitant intravenous-conscious sedation or short-acting general anesthesia.⁷ The trauma to soft tissue and the maxillary and mandibular alveolar bone results in release of inflammatory and algesic mediators at the peripheral surgical sites. Predictably, 3 to 4 hours after surgery, 95% or more of individuals have moderate to severe pain that in clinical trials can be used to distinguish active drugs from placebo, and also detect differences between moderately effective and highly effective analgesics.⁴ In addition, these are relatively healthy patients who are not on confounding medications, with an average age of 20 years.⁸ Therefore, this model is common in pivotal double-blind, randomized, placebo-controlled trials for US Food and Drug Administration (FDA) approval of analgesics.
Several early oral surgery analgesic studies have assessed peripherally acting analgesics. Both aspirin 650 mg and acetaminophen (APAP) 650 mg produced significantly better pain-relief scores than placebo, with approximate equal analgesia.⁵ APAP and aspirin have linear dose-response curves with a ceiling effect thought to be in the neighborhood of 1,000 mg.^4,5,9 The maximum daily doses of APAP and aspirin should not exceed 4,000 mg, and lower doses might often deliver adequate analgesia with a lower risk of rare but serious adverse events.⁹ When calculating total daily doses, it is important to appreciate that opioid combination products and over-the-counter (OTC) medications may contain APAP or aspirin.^4,10 To go beyond the analgesic effects of maximum doses of aspirin or APAP, an optimal or near-optimal dose of aspirin or APAP can be combined with a centrally acting opioid (such as oxycodone 5 mg, hydrocodone 10 mg, codeine 60 mg, or tramadol 75 mg).¹¹ In several studies, an opioid alone produced similar or inferior postoperative pain relief to aspirin or APAP alone.^4,6,11-13 However, combining an opioid with aspirin or APAP produced an additive analgesic effect, which is consistent with opioids producing analgesia by a mechanism different from the peripherally acting agents.^4,6,11-13 Because many combination formulations contain less than optimal doses of the peripherally acting component, under-dosing of these agents is common.¹ For example, a single tablet of one of the strengths of Percocet^® (APAP 325 mg/oxycodone 5 mg tablets) contains only 325 mg of APAP. The optimal doses of aspirin or APAP to prescribe when using these combination products has been reported to be 600 mg to 1,000 mg.¹⁴ Increasing the number of doses of combination products to achieve higher aspirin or APAP doses also increases the opioid dose. So while the increased doses tends to be more efficacious, they also induce a higher incidence of opioid-related side effects.^12,14,15 In addition, on January 13, 2011, the FDA mandated that manufacturers of APAP/opioid combination drugs limit the amount of APAP to no more than 325 mg in each tablet or capsule in an effort to reduce the incidence of APAP-associated overdose and accompanying hepatotoxicity. This requirement will be rolled in over the next 3 years and currently does not affect dosages of OTC APAP products.¹⁶
The newer nonsteroidal anti-inflammatory drugs (NSAIDs) at the upper end of their dose-response curve appear significantly more efficacious than APAP or aspirin 650 mg to 1,000 mg.4 In the United States, the current gold-standard analgesic in moderate to severe postoperative dental pain is ibuprofen 400 mg,^17,18which is as effective as codeine 60 mg with aspirin 650 mg.¹³ There are too few studies to demonstrate a definitive advantage of ibuprofen 600 mg or 800 mg over 400 mg in acute postoperative dental pain, and one study found no difference in analgesic effectiveness between ibuprofen 400 mg and 800 mg.^19,20 Similarly to the early studies of APAP and aspirin in postoperative dental pain, ibuprofen 400 mg alone is a more effective analgesic than single-entity morphine 60 mg, oxycodone 5 mg, and the novel, centrally acting analgesic tapentadol at 50-mg, 75-mg, and 100-mg dosage strengths.^21,22 It is thought that the anti-inflammatory and analgesic properties of NSAIDs (and most of their side effects) result from their inhibition of cyclooxygenase (COX)—a key enzyme in the production of postoperative pain and inflammation due to its ability to convert arachidonic acid to prostaglandins.⁴ Aspirin is unique in inactivating COX by irreversible acetylation, whereas the newer NSAIDs are reversible competitive inhibitors of COX.⁴ A number of NSAIDs are available in the United States, which do differ in terms of potential for gastrointestinal (GI) toxicity (ibuprofen demonstrates the lowest relative risk) and platelet inactivation.⁴
Ibuprofen 400 mg combined with an opioid has a faster onset of effect and greater peak effects than ibuprofen 400 mg alone.²² Pain relief with oxycodone 5 mg/ibuprofen 400 mg is superior to that achieved with oxycodone 5 mg/APAP 325 mg or hydrocodone 7.5 mg/APAP 500 mg.²³ Due to their different mechanisms of action, there is also an emerging compilation of study data which supports the strategy of combining an NSAID with APAP to provide analgesia greater than either APAP or the NSAID alone.^24-27 A recently published systematic review reported that the combination of an NSAID plus APAP provided pain relief greater than the NSAID alone in 9 of 14 postoperative pain studies.²⁵ With respect to postoperative dental pain, five of six studies showed reduced pain intensity and increased pain relief with the combination than the NSAID alone.^24-29 In the dental pain studies that displayed analgesic enhancement, APAP 500 mg to 1,000 mg was combined with the NSAID.

Other Therapeutic Approaches

Pre-emptive NSAIDs

Studies have demonstrated that preoperative administration of ibuprofen delays the onset of pain (by more than 100 minutes compared with placebo) and lessened the severity of postoperative dental pain as the effect of the local anesthetic dissipated, without increased side effects.^30,31 The beneficial effects of pre-emptive NSAID use is further illustrated by a study that showed that preoperative and postoperative administration of flurbiprofen achieved superior pain relief than APAP alone or in combination with oxycodone.³² This data supports the clinical strategy of administering an NSAID an hour before or immediately after the surgical procedure, and then dosing the NSAID on a fixed around-the-clock schedule for the first 24 to 48 hours. Preoperative dosing of NSAIDs is often avoided by dentists because of concerns that increased bleeding will result. While the amount of bleeding was not directly measured, the preoperative administration of a single dose of ibuprofen 400 mg or flurbiprofen 50 mg to 100 mg did not result in any significant increase in intraoperative or postoperative bleeding.^30-32 Short-term use of ibuprofen in particular has been shown to only marginally reduce platelet aggregation compared to other NSAIDs such as ketoprofen or aspirin.^33,34

Postoperative Long-Acting Local Anesthetic

Another therapeutic approach to attenuate postoperative pain is the administration of the long-acting local anesthetic, bupivacaine 0.5% with 1:200,000 epinephrine, during the immediate postoperative period.^35,36Patients who had third molar extractions under general anesthesia were randomized to one of four groups: preoperative lidocaine 2% with 1:100,000 epinephrine, postoperative bupivacaine 0.5% with 1:200,000 epinephrine, both, or placebo injections.³⁶ In the bupivacaine groups, pain was not only diminished in the immediate postoperative period (0 to 4 hours), but also 48 hours after surgery compared with placebo and lidocaine alone.³⁶ This strategy is most effective if combined with pre-emptive and around-the-clock NSAIDs during the immediate postoperative period.

Relative Efficacy of Oral Analgesics: Synthesis of Evidence

A meta-analysis of randomized, double-blind studies of analgesics for acute pain after third molar extraction compared the relative efficacy of a single dose of several oral analgesics.³⁷ The number of patients with moderate or severe pain achieving at least 50% maximum pain relief over 4 to 6 hours was used to calculate the number needed to treat (NNT) with active drug to get one additional patient with at least 50% pain relief compared with placebo (Figure 1) (the lower the NNT, the more effective the analgesic).³⁷ Single-dose diclofenac 100 mg had the lowest NNT, followed closely by ibuprofen 400 mg.³⁷ It is important to note that the administration of diclofenac 100 mg will make it difficult to stay within maximum recommended daily dose guidelines for this drug, which is 150 mg per day. In contrast, ibuprofen 400 mg represents only one sixth of the maximum recommended daily dose guideline of 2,400 mg. Figure 1 also demonstrates that to the probable surprise of many clinicians, ibuprofen 400 mg displays a NNT that is approximately half that of the combination of APAP 600 mg plus codeine 60 mg (2.2 vs 4.3).

Figure 1 The 95% confidence interval of the number needed to treat (NNT) for at least 50% pain relief over 4 to 6 hours compared with placebo in third molar extraction trials.³⁷ Adapted with permission from Macmillan Publishers Ltd: British Dental Journal

In general postsurgical (non-dental) pain models, the NNT with single-dose ibuprofen 200 mg, 400 mg, and 600 mg were all similar at around 2.5 (Figure 2 ); although ibuprofen 800 mg had a lower NNT, this was based on only one study.¹⁹ Ibuprofen was at least as effective as optimal doses of combination opioid/APAP therapy and was superior to single-entity oxycodone 15 mg or APAP 325 mg combined with oxycodone 5 mg.

Figure 2 The 95% confidence interval of the number needed to treat (NNT) for at least 50% pain relief over 4 to 6 hours compared with placebo in acute postoperative pain trials

Current Practice Patterns

A survey of dental prescribing practices among oral surgeons after third molar extraction found that the preferred peripherally acting postoperative analgesic is ibuprofen (73.5%), but 85% of oral surgeons also almost always prescribe a centrally acting opioid analgesic, with the drug of choice being hydrocodone/APAP (64%).¹ On average, 20 tablets of hydrocodone/APAP are prescribed, with instructions in 96% of cases to "take as needed for pain."¹
Most of the available data on dentists' analgesic prescribing practices focus on oral surgeons. Recently, a statewide survey conducted in West Virginia evaluated dentists' analgesic prescribing patterns with an emphasis on opioids, and experiences with patient drug diversion and substance abuse.³⁹ Data from 52% of all dentists in West Virginia (mainly general dental practitioners), showed that the most frequently prescribed analgesic if no opioids were prescribed was NSAIDs (64%), followed by APAP (28%).³⁹ The most prescribed opioid was hydrocodone/APAP (73%).³⁹ The amount of opioids given after third molar extraction varied greatly, but 20 doses and a 3-day supply was most common. The pattern of days of therapy for the most common opioids prescribed was similar following root canal.³⁹
The question raised by these two studies is whether 20 tablets of an opioid/APAP combination agent is an appropriate amount after third molar extraction and what happens to unused opioids, if anything. Addressing the first part of the question, there is not a large amount of data about the number of days that dental patients are in pain after the procedure—but some studies provide an indication. In a study of dental impaction surgery causing moderate to severe pain, patients typically took NSAIDs (ibuprofen or meclofenamate) for between 4 and 6 days.¹⁸ After dental implant surgery, the typical dosing period with APAP/hydrocodone was between 2 and 3 days.⁴⁰ However, there needs to be flexibility in the number of days supply, because some people will legitimately need analgesics for 6 or 7 days, with 24% in one study still taking analgesics on postoperative day 10 after removal of four third molars.⁸
The second part of the question—what happens to unused opioids⁴² The National Survey on Drug Use and Health (NSDUH) found that among persons aged 12 or older in 2007 to 2008 who used pain relievers non-medically (without a prescription) in the past 12 months, 56% got the pain relievers they most recently used from a friend or relative for free.⁴¹ Another 9% bought them from a friend or relative, and 5% took them from a friend or relative without asking.⁴¹ Nearly one fifth (18%) indicated that they got the drugs they most recently used through a prescription from one doctor.⁴¹ In 82% of the instances where non-medical users of prescription pain relievers obtained the drugs from a friend or relative for free, the individuals indicated that their friend or relative had obtained the drugs from just one doctor.⁴¹ Recent data from Utah showed that 72% of respondents who were prescribed an opioid had leftover medication, and 71% of those with leftover medication kept it.⁴³ This demonstrates the importance that all clinicians—including dentists—prescribe no more than the number of doses needed based on the usual duration of pain severe enough to require opioids for that condition;⁴³ further research in this area is warranted in order to better guide dentists. In addition, clinicians must counsel patients to dispose of unused medication once the condition has resolved.⁴³ The Office of National Drug Control Policy guidelines for the disposal of prescription drugs instructs patients not to flush prescription drugs down the toilet or drain unless the label or accompanying patient information specifically instructs them to do so.⁴⁴ Patients should take advantage of community prescription drug take-back programs.⁴⁵ If such programs are not available, patients can access an online FDA-maintained list of medicines recommended for flushing.

Recommendations for Analgesic Prescribing for Acute Dental Pain

After a review of the literature, a flexible analgesic strategy for the management of acute pain developed in 1995 by the American Association of Endodontists was selected by the authors as a template for an updated set of acute dental pain prescribing recommendations.⁴⁷ Input from other published guidelines was also incorporated into the present recommendations.^48-50 The revisions that were made were derived from the review of clinical trial and meta-analysis data in both dental and non-dental acute postoperative pain, together with the recent FDA mandate concerning prescription APAP dosages.¹⁶ The current recommendations are based on procedures that are likely to induce mild, moderate, or severe pain (Figure 3 ). This therapeutic paradigm for pain management considers NSAIDs as the first line drugs in most cases of postoperative dental pain based on evidence that optimal doses of NSAIDs are superior in efficacy to single-entity opioids, and are at least as efficacious as optimal doses of peripheral/opioid combination drugs. NSAIDs also have a more favorable side-effect profile than agents that contain an opioid.

Figure 3 Analgesic prescribing recommendations for acute post-procedural pain.

For patients who can tolerate NSAIDs, ibuprofen 200 mg to 400 mg as needed for pain every 4 to 6 hours is the gold standard for mild pain. If this regimen provides inadequate pain relief, or it is anticipated that the patient will have moderate pain, ibuprofen 400 mg to 600 mg around-the-clock every 4 to 6 hours for the first 24 hours is recommended, followed by ibuprofen 400 mg as needed for pain every 4 to 6 hours. If ibuprofen 400 mg to 600 mg provides inadequate pain relief or moderately severe pain is anticipated, ibuprofen 400 mg to 600 mg plus APAP 500 mg every 6 hours is recommended around-the-clock for the first 24 hours. If that is inadequate, or if severe postoperative pain is anticipated, ibuprofen 400 mg to 600 mg plus APAP 650 mg, combined with an opioid equivalent of hydrocodone 10 mg every 6 hours for the first 48 hours is recommended.
For patients in whom NSAID-like drugs are contraindicated, APAP 650 mg to 1,000 mg is the first-line analgesic. If this regimen provides inadequate pain relief, or it is anticipated that the patient will have moderate pain, APAP 650 mg plus hydrocodone 10 mg around the clock every 6 hours for 24 hours is suggested; then APAP 650 mg as needed for pain every 6 hours. If the pain relief is inadequate or severe pain is anticipated, APAP 650 mg and an opioid equivalent to oxycodone 10 mg around the clock every 6 hours for 48 hours is recommended (nuisance side effects should be anticipated in an opioid-naïve individual); then APAP 650 mg to 1,000 mg as needed for pain every 6 hours.
Additional considerations are the use of the long-acting local anesthetic, bupivacaine, immediately after the completion of the surgical procedure, to reduce postoperative pain in both the immediate and distant postoperative period; and the use of pre-emptive NSAIDs to delay the onset of postoperative dental pain.

Special Populations

Substance Abuse Disorders

Dentists should routinely at least ask new patients about their history of addiction or substance abuse—however, in the West Virginia survey of dental professionals, 36% of respondents acknowledged not doing so.³⁹ The NSDUH reported that the rate of current (past-month) illicit drug use among persons aged 12 or older in 2008 was 8%⁴¹—therefore, it is not unreasonable that dentists should expect to encounter such patients in their practice. Patients with a history of substance abuse include those that are in drug-free recovery, those that are in recovery with adjuvant ²Alcoholics may be at greater risk for the hepatotoxic effects of APAP and the ulcerogenic effects of SAIDs.⁵¹ Dental professionals must learn to recognize these individuals, determine their status in the recovery process, and establish practices to manage their acute pain appropriately.²
It is important to consult with such patients' primary care provider, as well as the addiction treatment provider.²Dental professionals should also collaborate with patients' family members or support network, particularly if it is established that a controlled substance is necessary for their care (eg, have a "trusted other" dispense each dose of medication rather than giving the patient unsupervised control over the medication).² It is recommended that patients be encouraged to intensify their involvement in a recovery program before and after dental treatment that may involve surgery or anticipated postoperative pain.² Informed consent—including the risk of initiating a relapse—and strict parameters for treatment are essential, and around-the-clock rather than PRN administration of opioids is recommended to provide timely and effective pain relief and reduce the likelihood that inadequate pain relief will be misinterpreted as drug-seeking behavior.²
Opioid analgesic tolerance may be problematic in patients enrolled in methadone or buprenorphine maintenance programs. Additional therapy with opioids for anticipated acute pain should always be discussed with their buprenorphine or methadone maintenance therapy prescriber.³ Alternatively, the addition of an NSAID to a buprenorphine or methadone regimen is also a reasonable option because of the proven additive analgesic effects of combined NSAIDs and opioids.^13,22,23
Because community dentists see patients frequently and develop long-term relationships with them, they are in a unique position for screening in a public health role. In order to be able to direct patients that they identify as in need of substance abuse treatment, they should become familiar with the American Society of Addiction Medicine's Patient Placement Criteria, and begin to investigate what addiction resources are available in their community.⁵²

Renal and Hepatic Disease

Because toxicities associated with peripherally acting analgesics include renal and hepatic disease, caution is indicated when using these agents in patients with a history of such disorders.^4,51,53,54 Hepatotoxicity is extremely rare with proper use of the currently available analgesics and is most often associated with APAP overdose.⁴ However, because APAP is so commonly included in OTC and prescription combination formulations, unintentional overdose is often reported.^53,54 It has been reported that patients aged older than 65 years are at greater risk for acute liver toxicity with prolonged APAP therapy, although this finding may relate primarily to concomitant drug use in this population.⁴

Future Research Agendas in Acute Dental Pain

Research is needed in a number of areas related to the management of acute postoperative pain in the dental setting. Gaps in current pharmacologic knowledge include the efficacy of prescribing analgesics at fixed intervals versus as needed; demographic, behavioral, and genetic factors that potentially predict pain relief efficacy, adverse outcomes, and abuse; the utility of NSAID/APAP combinations in limiting the need for opioid analgesics; and the utility of long-acting local anesthetics to manage postoperative pain. It is also necessary to better understand practice patterns for pain management and analgesic use (both opioid and non-opioid) among general dentists and dental specialists, their perceptions of risk and safety of opioid analgesics, and their awareness about the increasing problem of prescription drug misuse and abuse; and guide these practitioners in optimal and safe prescribing of analgesics for acute pain in all patients.

References

1. Moore PA, Nahouraii HS, Zovko JG, Wisniewski SR. Dental therapeutic practice patterns in the U.S. II. Analgesics, corticosteroids, and antibiotics. Gen Dent. 2006;54(3):201-207.
2. Lindroth JE, Herren MC, Falace DA. The management of acute dental pain in the recovering alcoholic. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2003;95(4):432-436.
3. Heit HA, Gourlay DL. Buprenorphine: new tricks with an old molecule for pain management. Clin J Pain. 2008;24(2):93-97.
4. Hersh EV, Moore PA, Ross GL. Over-the-counter analgesics and antipyretics: a critical assessment. Clin Ther. 2000;22(5):500-548.
5. Cooper SA. Comparative analgesic efficacies of aspirin and acetaminophen. Arch Intern Med. 1981;141(3):282-285.
6. Cooper SA. Models for clinical assessment of oral analgesics. Am J Med. 1983;75(5A):24-29.
7. Moore PA, Nahouraii HS, Zovko JG, Wisniewski SR. Dental therapeutic practice patterns in the U.S. I. Anesthesia and sedation. Gen Dent. 2006;54(2):92-98.
8. Snyder M, Shugars DA, White RP, Phillips C. Pain medication as an indicator of interference with lifestyle and oral function during recovery after third molar surgery. J Oral Maxillofac Surg. 2005;63(8):1130-1137.
9. McQuay HJ, Moore RA. Dose-response in direct comparisons of different doses of aspirin, ibuprofen and paracetamol (acetaminophen) in analgesic studies. Br J Clin Pharmacol. 2007;63(3):271-278.
10. Schilling A, Corey R, Leonard M, Eghtesad B. Acetaminophen: old drug, new warnings. Cleve Clin J Med. 2010;77(1):19-27.
11. Beaver WT. Aspirin and acetaminophen as constituents of analgesic combinations. Arch Intern Med. 1981;141(3):293-300.
12. Cooper SA, Precheur H, Rauch D, et al. Evaluation of oxycodone and acetaminophen in treatment of postoperative dental pain. Oral Surg Oral Med Oral Pathol. 1980;50(6):496-501.
13. Cooper SA, Engel J, Ladov M, et al. Analgesic efficacy of an ibuprofen-codeine combination.Pharmacotherapy 1982;2(3):162-167.

Plaque Formation and Marginal Gingivitis Associated with Restorative Materials

2011-09-27T19:22:00.000+03:00

The presence of restorative materials on tooth surfaces is perceived to be a contributing factor to periodontal disease. This observation is a result of the increased accumulation of plaque on restorations adjacent to the gingiva, which may lead to gingivitis. Plaque is believed to adhere better to restorations than to enamel. This may be due to the surface characteristics of restorative materials such as surface roughness and surface-free energy inherent in the materials. This article reviews the experimental studies of plaque formation on different restorative materials. In addition, clinical studies analyzing and comparing restorative materials and the consequent formation of gingivitis are reviewed. While in vitro and in vivo studies show variations in plaque formation among restorative materials and enamel, clinical studies demonstrate that the progression of gingivitis can be prevented if patients maintain adequate oral hygiene and home care. Therefore, instructing the patient to maintain proper oral hygiene and home care is more important than the choice of restorative material.
Plaque-induced gingivitis is gingival inflammation caused by bacterial plaque at the gingival margin. Prevalent in all ages of the dentate population, it is the most common form of periodontal disease.¹ Plaque is a biofilm composed of various microbial species in a matrix of microbial byproducts and host-derived factors and attaches to the tooth.² Local factors such as crowded teeth, tooth anatomy, and restorative margin discrepancies may alter the formation of bacterial plaque.³ Throughout the years, studies have considered the effects of the integrity of the restorative surface, type of restorative materials, and location of the restorative margin placement on the periodontal tissues as factors that exacerbate gingival diseases.⁴ One concern of clinicians is the placement of restorative margins and its impact on the violation of the biologic width. This may lead to gingival inflammation, clinical attachment loss, and bone loss due to the inflammatory response to the microbial plaque situated in deeply placed restorative margins. It appears that a minimum distance of 3 mm between alveolar bone and restorative margins is a prudent dimension in restorative treatment planning.⁵ A review⁶ of several clinical studies has shown varying degrees of microbial colonization when comparing restorative materials or when comparing them to natural teeth.
The topic of how different restorative materials affect plaque formation is important. The clinician may choose a specific restorative material over another based on
its known attraction to plaque and its potential to initiate gingival disease.
Formation of Plaque
Within seconds of polishing the teeth, a thin layer called the pellicle covers the tooth. This layer is composed of salivary components such as glycoproteins, phosphoproteins, enzymes, and other bacterial byproducts that coat the tooth surface. Then, the pellicle attracts bacteria through physiochemical interactions (such as van der Waals forces, electrostatic repulsive forces, and covalent, ionic, or hydrogen bonding). Through coaggregration and coadhesion, the motile bacteria attract other bacteria onto the tooth surface. Colonization of more bacteria ensues and forms a complex plaque biofilm.²
Plaque forms on both natural tooth and artificial surfaces. Surface roughness^7-10 and surface-free energy^11-14 may influence adhesion. Microscopy observations have shown that early microbial colonization of enamel surfaces tends to start in surface irregularities such as cracks, grooves, and abrasion defects. Other data have indicated roughening of intraoral surfaces spurs growth rate and maturation of supragingival plaque.¹² Conversely, physiochemical interactions between bacteria and the surface are affected by their charges and forces (van der Waals force and electrostatic repulsion). This surface-free energy influences bacterial adhesion. High-energy surfaces collect more plaque, bind the plaque more strongly, and select specific bacteria.¹²Although these factors interact, surface roughness is more important than surface-free energy.^10,13 Alternatively, subgingival plaque formation is influenced by other conditions such as a favorable environment for bacterial growth, making surface characteristics (roughness and energy) less influential. Overall, smooth surfaces and low surface-free energy are better conditions for minimizing supragingival plaque formation.^10,14 The complexity and pathogenicity of subgingival plaque formation in restorations placed subgingivally has been confirmed in a longitudinal study of 26 years, showing the placements of restorations below the gingiva are detrimental to gingival and periodontal health even in a population characterized as having good-to-moderate oral hygiene.
Plaque Adhesion to Restorative Materials
Investigations comparing plaque adhesion to various restorative materials and to enamel have been performed using in vitro and in vivo models.^9,10 One in vitro study¹⁶ concluded that bacterial adhesion to resin is associated with the characteristic extracellular ultrastructure of the streptococcal bacteria being studied. Hannig⁶ investigated the ultrastructural pattern of early plaque formation using transmission electron microscopy. This in vivo study compared amalgams, casting alloys, titanium, ceramics, glass polyalkenoate cements, composite resins, unfilled resins, and bovine enamel. The authors concluded early plaque formation behaves similarly in all materials, including enamel. Apparently, the pellicle layer is more important than the difference in material or enamel.^6,17 The pellicle layer seems to mask any variance among materials with regard to surface properties and biocompatibility. While previous research has analyzed the qualitative difference among dental materials and enamel, an in vitro study¹⁸examined the amount of bacteria adhering to different restorative materials using radioisotopes. This study compared amalgam, gold alloy, resin composite, and three ceramic materials. The investigation concluded that bacteria adhered most to amalgam, then to resin composite, then to casting gold restoration, and least to the ceramics. However, when amalgam and composite were polished, bacterial adhesion dramatically decreased in all materials, except porcelain. Regardless of the polishing method, no differences of bacterial adhesion were found in comparing the three ceramic materials.
Another in vitro study¹⁹similarly showed that Streptococcus mutans adhered more to glass ionomer, amalgam, composite, and resin-modified glass ionomer compared to ceramics. Other investigations^20,21 concluded amalgam and ceramics harbored less plaque compared to resins. A different in vitro study²² showed the effect of various degrees of surface roughness of porcelain on adhesion of bacteria. The researchers found the smoother surface had less plaque accumulation. Overall, smoother surfaces of restorative materials correlate with less plaque accumulation.¹⁹Yet in another study comparing porcelain, acrylic resin, gold, and metal,²³ the investigators found no difference in plaque retention between acrylic resin and porcelain. However, when contrasting porcelain with gold and metal, researchers found less plaque accumulation on porcelain than the two metals.
Other types of investigations looked at the viability of microbes on surfaces of the restorative materials. In vitro studies comparing plaque vitality to metals,²⁴ glass ionomer, resin-modified glass ionomer, composites, and resins^19,25-27 showed less plaque vitality in regard to the metals and fluoride-releasing restorative materials compared to resins and composites. Some investigators^28,29 attribute this to the antimicrobial property of fluoride.
A clinical study³⁰ investigated four finishing techniques on composite restorations. The composite restorations harbored plaque within 24 hours compared to 72 hours for the control teeth (enamel, polished metallic, or glazed porcelain). The authors attributed the statistically significant difference to the composite materials not being as smooth as the other restorative surfaces. A clinical experiment²⁰ found two types of ceramic restorations harbored less plaque than enamel or composite and surmised that polishing of the composites did not achieve the smoothness of the ceramics' finish. A clinical study³¹ compared the amount of S mutans in plaque from supragingival margins of 2-year-old amalgam, composite, and glass-ionomer restorations in children. The investigators found more plaque mass on composites compared to amalgams and observed the least amount of plaque on glass-ionomer restorations. The authors surmised the reason for less plaque on glass ionomer is due to this material's fluoride release. Plaque acidogenicity is reduced by fluoride, thereby hindering the growth of S mutans. However, one study³² that compared 1-year-old subgingival composite and glass-ionomer restorations in an unspecified population age group found no difference in the presence of S mutans. All patients had good oral hygiene. The differences between the previous two studies might be the location of plaque samples and patient age.
In summary, in vitro and in vivo experiments show that the pattern of early plaque formation is similar for different types of restorative materials compared to enamel due to the presence of the pellicle. As plaque matures, the amount of bacterial plaque adhesion depends on the smoothness of the restoration as seen by differences of plaque adhesion to different restorative materials and as observed in clinical investigations. Figure 1 shows plaque accumulation on two different restorative surfaces. The types of restorative material, such as glass ionomer, may also alter the formation of plaque; however, this needs further conclusive evidence.

Figure 1 Plaque accumulation on the occlusal surfaces of a gold and amalgam restoration in a patient with poor oral hygiene.

Consequence: Gingivitis
The formation and maturation of plaque on the surface of enamel or restorative materials will affect the adjacent soft tissue and elicit an inflammatory host response. This occurs if plaque is not removed. Experiments in which patients are purposely told not to perform oral hygiene for days to weeks so that plaque and gingivitis develop are experimental gingivitis models.³³ Using this model, one clinical study³⁴ found no difference in plaque accumulation, gingival condition, and inflammatory response (as measured by the presence of interleukin-1 cytokine levels) when comparing ceramic or composite restorations and enamel. Van Dijken et al³⁵ tested two types of composite materials (conventional and hybrid) and compared them to enamel using the model. Although the surface roughness of the composites varied, no significant difference in development of plaque or gingivitis between the two composites and the enamel surfaces resulted.
The previous group³⁶ studied three types of subgingival composite restorations (conventional, hybrid, and microfilled) that were 1 year to 2 years old or 3 years to 4 years old. They investigated the plaque retention and gingival conditions surrounding the different types of composites and ages and found no significant difference. The investigators noted that all the participants had good oral hygiene as shown by low plaque scores, thus no detrimental responses were seen. In clinical studies,^31,37 the authors compared the responses of the marginal gingiva to 1-year-old subgingivally located glass-ionomer and composite-resin restorations and enamel. They found no significant difference in the amount of plaque and degree of gingivitis. Participants also had good oral hygiene. In a clinical study³⁴ in which patients had adequate oral hygiene, no difference in plaque accumulation, gingival condition, and inflammatory response was seen when comparing ceramic or composite restorations and enamel.
A 1-year study³⁸ looked at the effects of subgingival Class V restorations (amalgam, glass ionomer, and composite) on the gingiva. These restorations did not significantly affect plaque scores, probing depth, and bleeding on probing when compared to sound control teeth. Another study³⁹ compared a novel Class V ceramic filling material to resin composite and found no difference in plaque formation and gingival inflammation. In both studies, the authors noted that patients had good oral hygiene. A clinical investigation⁴⁰ comparing interleukin-1 levels in gingival crevicular fluid adjacent to Class V restorations of calcium aluminate cement or resin composite determined no difference in a well-maintained patient population. One recent clinical study⁴¹compared the effects of subgingival glass-ionomer and microfilled composites on the periodontal tissues and formation of subgingival biofilm for a 6-month period. Although the glass-ionomer restoration had more positive clinical and theoretical effects (good marginal adaptation, reduced surface roughness, aluminum and fluoride release that may interfere with bacterial adhesion and inhibit bacterial metabolism) on the subgingival biofilm composition than the microfilled composite, both well-finished restorations did not negatively affect periodontal health. Like previous studies, the participants had good oral hygiene compliance. Figure 2, 3,4,5 and 6 show clinical situations of restorations and the presence or absence of gingivitis.
In summary, clinical studies investigating the effect of different restorative materials on the gingiva do not show a detrimental consequence as long as patients demonstrate adequate-to-good oral hygiene. In certain cases, patients with cervical lesions that harbor plaque may benefit from having a restoration placed because these areas become more cleansable. Figure 7, for example, shows plaque accumulation on teeth but not on the composite restoration.

Figure 2 Class V amalgam restoration on tooth No. 4 associated with plaque-induced gingivitis in a patient with poor oral hygiene

Figure 3 A gold foil restoration on tooth No. 29 and gold crown restoration on tooth No. 30 are adjacent to healthy gingiva. The patient has excellent oral hygiene.

Figure 4 Facial Class V composite on tooth Nos. 6 and 7 in a patient with excellent home care. Note the healthy gingiva adjacent to restorations even with the bulky restoration on tooth No. 7.

Figure 5 Class V composite restoration on tooth Nos. 9 and 10 associated with plaque-induced gingivitis in a patient with poor oral hygiene

Figure 6 The same patient in Figure 5 had undergone oral hygiene instructions along with scaling and root planing. Note that the inflammation has receded and the gingiva is healthier.

Figure 7 Tooth No. 13 has a composite restoration. Plaque has accumulated on the cervical areas of the adjacent teeth except on the restoration. No inflammation is seen adjacent to the restoration.

Conclusion
It has long been postulated that rough surfaces and high-energy surfaces tend to accumulate more plaque. This has been shown in mathematical models and in vitro and in vivo studies in which surfaces of different materials are demonstrated to be rougher than others. Most notably, porcelain surfaces are smoother than composite surfaces; therefore, the former will accumulate less plaque. Although this has been shown in a number of in vitro and in vivo studies, it is more important to analyze investigations that include the effects of plaque formation on the gingiva. Clinical studies have shown that people with good or adequate oral hygiene will not develop a markedly diseased gingiva despite the surface roughness or composition of the restorative material and consequent plaque formation. Therefore, the choice of a material is not as important as providing oral hygiene instructions to the patient. If a patient presents with less-than-adequate oral hygiene, then periodontal problems may be expected regardless of restorative material.

References
1. Mariotti A. Dental plaque-induced gingival diseases. Ann Periodontol. 1999;4(1):7-19.
2. Quirynen M, Teughels W, Kinder Haake S, et al. Microbiology of periodontal diseases. In: Newman MG, Takei HH, Carranza FA, Klokkevold PR, eds. Carranza's Clinical Periodontology. 10th ed. Philadelphia, PA: Saunders Elsevier; 2006:138-143.
3. Blieden TM. Tooth-related issues. Ann Periodontol. 1999;4(1):91-97.
4. Broadbent JM, Williams KB, Thomson WM, Williams SM. Dental restorations: a risk factor for periodontal attachment loss? J Clin Periodontol. 2006;33(11):803-810.
5. Padbury A Jr, Eber R, Wang HL. Interactions between the gingiva and the margin of restorations.J Clin Periodontol. 2003;30(5):379-385.
6. Hannig M. Transmission electron microscopy of early plaque formation on dental materials in vivo. Eur J Oral Sci. 1999;107(1):55-64.
7. Beyth N, Bahir R, Matalon S, et al. StreptococcuS mutans biofilm changes surface-topography of resin composites. Dent Mater. 2008;24(6):732-736.
8. Carlén A, Nikdel K, Wennerberg A, et al. Surface characteristics and in vitro biofilm formation on glass ionomer and composite resin. Biomaterials. 2001;22(5):481-487.
9. Nassar U, Meyer AE, Ogle RE, Baier RE. The effect of restorative and prosthetic materials on dental plaque. Periodontol 2000. 1995;8(1):114-124.
10. Teughels W, Van Assche N, Sliepen I, Quirynen M. Effect of material characteristics and/or surface topography on biofilm development. Clin Oral Implants Res. 2006;17(suppl 2):68-81.
11. Knorr SD, Combe EC, Wolff LF, Hodges JS. The surface free energy of dental gold-based materials. Dent Mater. 2005;21(3):272-277.
12. Quirynen M. The clinical meaning of the surface roughness and the surface free energy of intra-oral hard substrata on the microbiology of the supra- and subgingival plaque: results of in vitro and in vivo experiments. J Dent. 1994;22(suppl 1):S13-S16.
13. Quirynen M, Marechal M, Busscher HJ, et al. The influence of surface free energy and surface roughness on early plaque formation. An in vivo study in man. J Clin Periodontol. 1990;17(3):138-144.

What Constitutes "Ideal Dentistry" Today?

2011-09-27T16:54:00.001+03:00

Is dentistry tougher now than in years past? Absolutely.

Not that long ago, dentistry was a much simpler profession. Most practices were "drill and fill" offices where cavities occurred more frequently than now. Elective dentistry was not in high demand and comprised only a fraction of the average dental practice’s schedule. A limited range of cosmetic dentistry options was geared more for the rich and famous than for the average patient. Even orthodontics was something more for children of the well-to-do.
Things have clearly changed. In recent decades, dentistry has seen an explosion in technology and the number of services available to patients. Many of these services are in demand from the general public and are affordable for a growing number of patients.
All of this technical innovation, combined with shifting patient perceptions toward elective dentistry, has created a pressing question for dentists: What services are appropriate for their patients? Perhaps a larger issue needs to be addressed: Has the definition of "ideal treatment" become blurred?

Defining "Ideal Treatment"

I have always been a strong advocate of doctors offering ideal treatment to patients based on a comprehensive evaluation of their immediate and long-term oral health requirements. Before it can be determined whether patients will be interested in or have the financial capability to accept treatment, the ideal treatment plan should be developed and presented. In the process, patients will come to understand that the dentist has their best interests in mind.
Presenting ideal treatment also serves to:

educate patients.
increase patient awareness concerning recommended dentistry.
establish an order of priority for completing recommended procedures.

The benefit is that patients receive a complete picture of what it will take to achieve optimal oral health. There is, however, a complicating factor: They also receive information about services that are important to their overall well-being but not necessarily mandatory for good oral health. Should the doctor present these additional options as part of the big picture for oral health or rather as a distinctly separate plan? Many dentists find this a difficult question to answer.

Three Questions Dentists Must Ask Themselves

Today, cosmetic and implant dentistry both many options. These increased choices lead to several questions dentists find themselves asking:

What is ideal treatment for patients?
What are the ramifications if a patient does not accept the ideal recommendation?
Do certain elective services represent ideal treatment or are they simply a luxury?

The third question is the most difficult one to answer. In fact, dentists are unlikely to reach a true consensus on it. Consequently, many patients are not offered all available services. Dentists should keep in mind that patients depend heavily on their professional advice. Despite a wealth of dental data available on the internet, patients still prefer to receive their oral health information from their doctor first-hand.
To create a more comprehensive approach to ideal treatment for patients, dentists will be well served to institute the following:

Provide a thorough diagnosis for all patients, including periodontal, tooth, cosmetic, implant, and occlusal. This ensures that comprehensive dentistry options are evaluated for each individual.
Educate patients about all aspects of their oral health to ensure the optimal treatment outcomes. Also, explain whether the diagnosis represents a short-term or long-term problem.
Create treatment plans that explain all ideal options and why these are different from and/or better than other options.
Focus on multiple methods of payment options so that motivated patients can take advantage of ideal treatment within their financial capability.

The Benefits of Ideal Treatment

By promoting ideal treatment, dentists are better enabling patients to achieve optimal oral health. However, it seems that the definition of oral health needs to be expanded to include elective services. This is not to say, for example, that patients without a perfect anterior shade lack excellent oral health. Nevertheless, patients should be made aware of all their options.
At this point, the situation becomes complex for the dentist. Should cosmetic dentistry be recommended? Remember that today’s concept of ideal treatment is more likely to include services that are not necessarily essential to the patient’s overall health but may be beneficial to their psychological well-being and quality of life. The ethical aspects of cosmetic versus need-based dentistry (and the benefits to patients) will need to be determined by each individual doctor, bearing in mind that these options give patients greater freedom to determine how they wish to pursue their oral health and sense of well-being.

Conclusion

Like many professions, dentistry has become more complex with each passing year. New services present greater opportunities for dentists and patients. Once a dentist has established his or her definition of ideal treatment, it should be presented to patients in an educational manner that makes them aware of not only their options but also the ramifications of completing—or not completing—treatment.
Is there a right answer to what constitutes ideal treatment? Yes—whatever allows dentists to continue serving patients in the most comprehensive manner and motivates patients to take pride in their appearance and their oral health.

About the Author

Roger P. Levin, DDS is the founder and CEO of Levin Group in Owings Mills, Maryland.

Periodontal Probing Systems: A Review of Available Equipment

2011-09-27T16:39:00.000+03:00

The periodontal pocket, one of the definitive signs of periodontal disease, is the most common parameter to be assessed by dental clinicians. Periodontal probes have been the instruments most commonly used to locate and measure these pockets. Regular use of periodontal probes in routine dental practice facilitates and increases the accuracy of the process of diagnosing the condition, formulating the treatment, and predicting the outcome of therapy. Advances in the field of periodontal probing have led to the development of probes that may help reduce errors in determining this parameter used to define the state of active periodontal disease. One such advance is the emergence of probes that purportedly assess periodontal disease activity noninvasively. The selection of periodontal probe depends on the type of dental practice: a general dental practitioner would require first- or second-generation probes, while third- through fifth-generation probes generally are used in academic and research institutions as well as specialty practices.
The periodontal pocket, one of the definitive signs of periodontal disease, is the most common parameter to be assessed by dental clinicians. One of the more reliable and convenient ways of detecting, measuring, and assessing the status of periodontal disease activity is through
the use of periodontal probes.Periodontal probing permits dentists to identify sites with a history of periodontal disease or those at risk for periodontal breakdown. Described by Orban as the "eye of the operator beneath the gingival margin," periodontal probes are an essential part of a complete dental examination.¹

Uses of Periodontal Probes

The word probe is derived from the Latin word Probo, which means "to test." Periodontal probes are used primarily to detect and measure periodontal pockets and clinical attachment loss. In addition, they are used to locate calculus; measure gingival recession, width of attached gingiva, and size of intraoral lesions; identify tooth and soft-tissue anomalies; locate and measure furcation involvements; and determine mucogingival relationships and bleeding tendencies.²However, periodontal probing has its limitations. Reading errors may result from naturally occurring states, such as interference from the calculus on the tooth or root surface, the presence of an overhanging restoration, or the crown's contour. Another factor is operator error, such as incorrect angulation of the probe, the amount of pressure applied to the probe, misreading the probe, recording the data imprecisely, and miscalculating the attachment loss.³
Various factors, such as probe-tip size, angle of insertion of the probe, probing pressure, precision of probe calibration, and degree of inflammation in the underlying periodontal tissues, affect the sensitivity and reproducibility of measurements.⁴ Because the probe passes through the junctional epithelium into the underlying connective tissue in an inflamed gingival sulcus, readings of clinical pocket depth obtained with the periodontal probes do not normally coincide with the measurements up to the base of the pocket.⁴
The National Institute for Dental and Craniofacial Research (NIDCR) has defined eight criteria for overcoming the limitations of conventional periodontal probing. Table 1 shows how conventional probing criteria has been altered by the NIDCR for this objective.

Periodontal Probe Selection and Type of Dental Practice

For consistency of use and academic purposes, in 1992, Pihlstrom et al⁶ classified probes into three generations. In 2000, Watts⁷ extended this classification by adding fourth- and fifth-generation probes. These various generations, along with their advantages and disadvantages, are in Table 2.

Various periodontal probes cater to different needs. Selecting the appropriate periodontal probe is dependent on the type of dentistry a clinician practices. The needs of a general dentist are different from those of a periodontist who usually requires a more specialized set of periodontal probes. Research facilities and academic institutions can afford and effectively use more complex and sophisticated periodontal probes. Also, because the latest generations of probes work in conjunction with computers, the state of computerization in a dental practice has to be considered during the selection process.
Periodontal probes suitable for a general dental practice:

First-generation
Second-generation

Periodontal probes suitable for a dental practice with an interest in periodontics:

First-generation
Aecond-generation
Third-generation (if computerization is adequate)

Periodontal probes suitable for a specialty periodontal practice and university and research institutions:

Second-generation
Third-generation
Fifth-generation

Periodontal Probe Generations
First-Generation (Conventional) Probes
Conventional or manual probes (Figure 1)) do not control for probing pressure and are not suited for automatic data collection. These probes most commonly are used by general dental practitioners as well as periodontists. Invented in 1936 by periodontist Charles H.M. Williams, the Williams' periodontal probe is the prototype or benchmark for all first-generation probes. These probes have a thin stainless steel tip of 13 mm in length and a blunt tip end with a diameter of 1 mm. The graduations on these probes are 1 mm, 2 mm, 3 mm, 5 mm, 7 mm, 8 mm, 9 mm, and 10 mm. (The 4-mm and 6-mm markings are absent to improve visibility and avoid confusion in reading the markings.) The probe tips and handles are enclosed at 130^o.

Figure 1 First-generation periodontal probes (left to right): William’s Graduated, CPITN, UNC-15, Goldman Fox, Naber’s.

The Community Periodontal Index of Treatment Need (CPITN) was designed by Professors George S. Beagrie and Jukka Ainamo in 1978. CPITN probes are recommended for use when screening and monitoring patients with the CPITN index. The index and its probes were first described in World Health Organization's (WHO) Epidemiology, etiology, and prevention of periodontal diseases. Report of a WHO Scientific Group.⁹ The FDI World Dental Federation/WHO Joint Working Group 1 has advised the manufacturers of CPITN probes to identify the instruments as CPITN–E (epidemiologic), which have 3.5-mm and 5.5-mm markings, and CPITN–C (clinical), which have 3.5-mm, 5.5-mm, 8.5-mm, and 11.5-mm markings. CPITN probes have thin handles and are lightweight (5 gm). The probes have a ball tip of 0.5 mm, with a black band between 3.5 mm and 5.5 mm, as well as black rings at 8.5 mm and 11.5 mm.
University of Michigan O probes have markings at 3 mm, 6 mm, and 8 mm. A modification of this probe with Williams' markings also is available. University of North Carolina-15 (UNC-15) probes are color-coded at every millimeter demarcation. They are the preferred probe in clinical research if conventional probes are required.
The Naber's probe is used to detect and measure the involvement of furcal areas by the periodontal disease process in multirooted teeth. Naber's probe also is used in the assessment of more complex clinical cases, including those with a restorative treatment. These probes can be color-coded or without demarcation.

Second-Generation (Constant-Pressure) Probes
The second-generation instruments are pressure sensitive, allowing for improved standardization of probing pressure. Scientific literature that demonstrated probing pressure should be standardized and not exceed 0.2 N/mm2 led to the development of their probes.¹⁰ Second-generation probes can be used in general dental practices, as well as periodontal practices, and do not require computerization in the operatory. The True Pressure Sensitive (TPS) probe Figure 2 is the prototype for second-generation probes. Introduced by Hunter in 1994, these probes have a disposable probing head and a hemispheric probe tip with a diameter of 0.5 mm. A controlled probing pressure of 20 gm is usually applied. These probes have a visual guide and a sliding scale where two indicator lines meet at a specified pressure.

Figure 2 The True Pressure Sensitive Probe, a second-generation periodontal probe. The indicators lines meet at a specified force of 20 gm.

In 1977, Armitage designed a pressure-sensitive probe holder to standardize the insertion pressure and determine how accurate probing pressure of 25 pounds affected the connective-tissue attachment.¹² In 1978, van der Velden devised a pressure-sensitive probe with a cylinder and piston connected to an air-pressure system. Subsequently, it was modified with a displacement transducer for electronic pocket-depth reading.¹³
The electronic pressure-sensitive probe, allowing for control of insertion pressure, was introduced by Polson in 1980. This probe has a handpiece and a control base that allows the examiner to control the probing pressure. The pressure is increased until an audio signal indicates that the preset pressure has been reached.¹⁴ Polson's original design was modified by its initial users: That probe is known as the Yeaple probe, which is used in studies of dentinal hypersensitivity.

Third-Generation (Automated) Probes

In spite of the advances in second-generation probes, other sources of errors, such as in reading the probe, recording data, and calculating attachment level, still needed to be addressed. Third-generation probes were developed to help minimize these mistakes by using not only standardized pressure, but also digital readouts of the probes' readings and computer storage of data. This generation includes computer-assisted direct data capture to reduce examiner bias and allows for greater probe precision. These probes require computerization of the dental operatory and can be used by periodontists and academic institutions for research.
The Foster-Miller probe (Foster-Miller, Inc, Waltham, MA) is the prototype of third-generation probes. Devised by Jeffcoat et al¹⁶ in 1986, this probe has controlled probing pressure and automated detection of the cementoenamel junction (CEJ). The components of the probe are: a pneumatic cylinder, a linear variable differential transducer (LVDT), a force transducer, an accelerator, and a probe tip.
The main mechanism of action of the Foster-Miller probe is by detection of the CEJ. The ball tip moves or glides over the root surface at a controlled speed and preset pressure. Abrupt changes in the acceleration of the probe movement (recorded on a graph) indicate when it meets the CEJ and when it is stopped at the base of the pocket. Under controlled pressure, the probe tip is extended into the pocket and refracted automatically when the base of the pocket is reached. Position and acceleration-time histories are analyzed to determine attachment level and pocket depth. As with all devices, the Foster-Miller probe has advantages and disadvantages. The main advantage is the automatic detection of the CEJ, which is a better landmark than gingival margin, because the position of the gingival margin may change depending on inflammation or recession.¹⁷ The main disadvantage is that it can deem root roughness or root surface irregularities as the CEJ.¹⁶
The Florida Probe^® (Florida Probe Corp, www.floridaprobe.com) was devised by Gibbs et al¹⁸ in 1988. This probe consists of a probe handpiece and sleeve; a displacement transducer; a foot switch; and a computer interface/personal computer. The hemispheric probe tip has a diameter of 0.45 mm, and the sleeve has a diameter of 0.97 mm Figure 3.Constant probing pressure of 15 gm is provided by coil springs inside the handpiece. The edge of the sleeve is the reference from which measurements are made, and the probe has Williams' markings; however, actual measurement of the pocket depth is made electronically and transferred automatically to the computer when the foot switch is pressed.

Figure 3 The Florida Probe with tip and sleeve diameter (photograph courtesy of Florida Probe Corporation).

These probes provide a constant probing pressure of 15 gm, which can be overridden when necessary, for accuracy and patient comfort. They also can record missing teeth, recession, pocket depth, bleeding, suppuration, furcation involvement, mobility, and plaque assessment.¹⁹Each measurement is recorded with potentially 0.2-mm accuracy. Comparison to previous data can be made more quickly and accurately. (The system shows black arrows for changes between 1 mm and 2 mm, and red arrows are used for changes > 2 mm.) Also, there is a chart showing diseased sites, which can be used in patient education.¹⁹ The Florida Probe does have some disadvantages, which include underestimating deep probing depths a lack of tactile sensitivity. Also, clinicians need to be trained to operate these probes.²⁰
The Toronto Automated probe, devised by McCulloch and Birek in 1991 at University of Toronto, used the occlusoincisal surface to measure relative clinical attachment levels.²¹ The sulcus is probed with a 0.5-mm nickel-titanium wire that is extended under air pressure. It controls angular discrepancies by means of a mercury tilt sensor that limits angulation within ± 30º. This probe has the advantage of an incorporated electronic guidance system to improve precision in probe angulation. It also estimates the biophysical integrity of the dentogingival junction by measuring intrapocket probing velocity.²² The disadvantages are associated with positioning: It is difficult to measure second and third molars, and patients have to position their heads in the same place to reproduce readings.²³
The InterProbe™ (The Dental Probe Inc, www.interprobe.com), also known as the Perio Probe, is a third-generation probe with a flexible probe tip, which curves with the tooth as the probes enter the pocket area.¹⁷ Stainless steel probes push the gingiva away from the tooth, causing pain, whereas the InterProbe gently slides in. The probe produces accurate readings of periodontal pockets with its standardized 15 gm of pressure. The probe's optical encoder handpieces uses constant probing pressure, which provides repeatable measurement of pocket depth and attachment loss.

Fourth-Generation Probes

Fourth-generation refers to three-dimensional (3D) probes. Currently under development, these probes are aimed at recording sequential probe positions along the gingival sulcus. They are an attempt to extend linear probing in a serial manner to take into account the continuous and 3D pocket being examined.⁷

Fifth-Generation Probes

Despite all the advances in earlier generation probes, they remain invasive and, at times, their use can be painful to patients. Plus, with these earlier generation probes, the probe tip usually crosses the junctional epithelium. Fifth-generation probes are being devised to eliminate these disadvantages. Probes are being designed to be 3D and noninvasive: an ultrasound or other device is added to a fourth-generation probe. Fifth-generation probes aim to identify the attachment level without penetrating it.
The only fifth-generation probe available, the UltraSonographic (US) probe (Visual Programs, Inc,www.usprobe.com), uses ultrasound waves to detect, image, and map the upper boundary of the periodontal ligament and its variation over time as an indicator of the presence of periodontal disease. The US probe was devised by Hinders and Companion at the NASA Langley Research Center.²⁴ This small intraoral probe has an ultrasound beam projection area close enough in size to the width of the periodontal ligament space to give the optimal coupling and small enough to inspect the area between the teeth, while still delivering sufficient signal strength and depth of penetration to image the periodontal ligament space. To probe these structures ultrasonically, a narrow beam of ultrasonic energy is projected down between the tooth and bone from a transducer, which is scanned manually along the gingival margin. The transducer is mounted at the base of a dual-taper, convergent-divergent coupler to provide an acoustically tapered interface with a throat area on the order of 0.5 mm. This constitutes an active area reduction from the transducer element to the aperture of 20:1. Such a reduction is mandated by the geometry and the very small window afforded by the gingival margin. An added virtue of attaining this small a tip size is the ability of the ultrasonic probe to help the clinician examine the area between the teeth, which is where periodontal disease is most likely to occur.
The ultrasound transducer is mounted in the probe-tip shell, which also incorporates a slight flow of water to ensure good coupling of the ultrasonic energy to the tissues. The couplet water can come either from a suspended intravenous-type sterile bag or plumbed from the dental-unit water source. The focused ultrasonic beam is transmitted into the pocket in the same orientation as the insertion of a manual probe Then, the probe is moved along the gingival margin, so the two-dimensional graphical output corresponds to the results a clinician gets from "walking the sulcus" with a manual probe. However, ultrasound gives more information because secondary echoes are recorded from tissue features at various depths. It appears likely that the technique also will be able to provide information on the condition of the gingival tissue and the quality and extent of the epithelial attachment to the tooth surface. This may supply valuable data to aid the clinician in the diagnosis and treatment charting of these diseases.

Nonperiodontal Probes

Calculus Detection
Calculus detection probes detect subgingival calculus by means of audio readings and are reported to increase chances of subgingival calculus detection.²⁶ Currently, the DetecTar probe (DENTPLY Professional, www.dentsply.com) is the only calculus detection probe on the market. This device has a lightweight, well-balanced handpiece, which can be autoclaved, and it produces an audible beep to signify calculus detection (beep function can be disengaged). This probe may augment standard methods of calculus detection; however, it is expensive and the handpiece is bulkier than a standard periodontal probe. The probe has a short waterline hookup, which may prevent ergonomic placement of the unit, and it does not have a published waterline treatment protocol. As with many automated probes, there is potential for false positives and false negatives; therefore, further research is required.
Periodontal Disease Evaluation System
The Diamond Probe^®/Perio 2000^® System (Diamond General Development Corp,www.lifesciencesworld.com) reportedly detects periodontal disease during routine dental examinations by measuring relative sulfide concentrations as an indicator of gram-negative bacterial activity. The system consists of a single-use disposable probe tip with microsensors connected to a main control unit.²⁷ The probe might detect periodontal disease at an early stage and might find an active site that requires treatment. However, the probing pressure is not controlled. Also, periodontal disease can be caused by bacteria that do not produce volatile sulfur compounds, creating the potential for some disease activity to be missed.²⁸
The Periotemp^® Probe (Abiodent Inc) is a temperature-sensitive probe, which reportedly detects early inflammatory changes in the gingival tissues by measuring temperature variations in these tissues.²⁹ The Periotemp Probe detects pocket temperature differences of 0.1oC from a referenced subgingival temperature.³⁰ This probe has two light indicating diodes: red-emitting diode, which indicates higher temperature, denoting risk is twice as likely for future attachment loss; and green-emitting diode, which indicates a lower temperature, indicating lower risk. This probe can detect initial inflammatory changes; therefore, treatment can be initiated at an early stage.³⁰ However, the presence of surface cooling caused by breath airflow may further complicate the determination of even a normal temperature distribution.³¹

Conclusion

Newer developments in the field of periodontal probes provide the potential for error-free determination of pocket depth and clinical attachment level at a very early stage. Screening periodontal diseases earlier is gaining importance as these diseases are being associated with systemic conditions. With more research and innovation, the advent of newer error-free probes may resolve the remaining problems and those yet to be realized.

References

1. Orban B, Wentz FM, Everett FG, et al. Periodontics—A Concept: Theory and Practice. St Louis, MO: C.V. Mosby Co; 1958:103.
2. Wilkins EM. Examination procedures. In: Wilkins EM. Clinical Practice of the Dental Hygienist. 9th ed. Philadelphia, PA: Lippincott Williams and Wilkins; 2005:222-245.
3. Badersten A, Nilvéus R, Egelberg J. Reproducibility of probing attachment level measurements.J Clin Periodontol. 1984;11(7):475-485.
4. Listgarten MA, Mao R, Robinson PJ. Periodontal probing and the relationship of the probe tip to periodontal tissues. J Periodontol. 1976;47(9):511-513.
5. Parakkal PF. Proceedings of the workshop on quantitative evaluation of periodontal diseases by physical measurement techniques. J Dent Res. 1979;58(2):547-553.
6. Pihlstrom BL. Measurement of attachment level in clinical trials: Probing methods. J Periodontol. 1992;63(12 Suppl):1072-1077.
7. Watts TLP. Assessing periodontal health and disease. In: Periodontics in Practice: Science with Humanity. New York, NY: Informa Healthcare; 2000:33-40.
8. Williams CHM. Some newer periodontal findings of practical importance to the general practitioner. J Can Dent Assoc. 1936;2:333-340.
9. World Health Organization. Epidemiology, Etiology and Prevention of Periodontal Diseases. Report of a WHO Scientific Group. Geneva, Switzerland: World Health Organization; 1978. Technical Report Series No. 621.
10. Hefti AF. Periodontal probing. Crit Rev Oral Biol Med. 1997;8(3):336-356.

COMBINATION SYNDROME SYMPTOMATOLOGY AND TREATMENT

2011-09-27T13:19:00.000+03:00

Combination syndrome (CS) is one of the most fascinating oral conditions yet is poorly understood and underappreciated in the literature and clinical practice. This article reviews the most important literature on this subject and analyzes the etiology, symptomatology, diagnosis, and current therapeutic modalities for treatment in an attempt to better understand CS. The syndrome represents an example of a complex pathologic condition of the entire stomatognathic system with a multitude of hard-tissue, soft-tissue, and occlusal changes. These changes, initiated by a certain sequence of events, beginning with a prolonged period of tooth loss, can lead to severe bone atrophy in different regions of the jaws, loss of masticatory function, and the need for complex treatment. Implant rehabilitation of these patients in a preventative approach with cooperation of the entire dental team is emphasized.

Kelly proposed the name combination syndrome (CS) in his original article¹ published in 1972 in the Journal of Prosthetic Dentistry. In 2003, this article was reprinted as a classic in the same journal.² Although some of the symptoms were known previously, Kelly had proposed a new condition by connecting the variety of known characteristic symptoms into one syndrome.
“The Glossary of Prosthodontic Terms”³ defines CS as “the characteristic features that occur when an edentulous maxilla is opposed by natural mandibular anterior teeth, including loss of bone from the anterior portion of the maxillary ridge, overgrowth of the tuberosities, papillary hyperplasia of the hard palate’s mucosa, extrusion of the lower anterior teeth, and loss of alveolar bone and ridge height beneath the posterior mandibular removable dental prosthesis bases—also called anterior hyperfunction syndrome.”
It also is in the “Glossary of Implant Terms”⁴ as “a condition caused by the presence of lower anterior teeth and an absence of the posteriors, resulting in significant maxillary anterior alveolar resorption.” This oral condition is viewed as a rarely occurring syndrome with most signs and symptoms appearing in approximately 24% of the population wearing a maxillary complete denture as opposed to a bilateral-distal extension partial denture.⁵ The CS literature is full of controversy regarding this condition, including uncertainty in regard to identifying it as a medical syndrome.⁶
There are few studies of long-term results and the association with implant and prosthetic characteristics, patients’ medical conditions, and implant survival outcomes in partially edentulous patients missing posterior teeth.⁷ Classification of CS in a variety of partially edentulous cases recently has been proposed.⁸ Based on a literature reviewwea and the author’s experience, this article discusses the symptoms in the order of their typical clinical appearance and conventional and implant treatment for this condition.

Symptomatology
Development of CS stems from traumatic occlusion. The most common initiating scenario involves complete loss of teeth in the maxilla and partial loss of teeth in the mandible, with preserved anterior teeth causing a deficiency of masticatory function. Presence of complete maxillary and partial class I mandibular removable dentures only partially buffers a significant reduction of occlusal function. Loss of function in skeletal bones leads to nonuse atrophy of supporting bone and attached muscles, and jaws are no exception to this rule. For patients with CS, loss of posterior teeth and deficiency in mastication eventually lead to alveolar bone resorption in the posterior quadrants of the jaws. Further, the posterior mandible is more likely than the posterior maxilla to experience pronounced atrophy after tooth loss. This atrophy pattern occurs not only because of loss of function but also resorptive changes from denture wear^9-14and the age-related decrease of blood supply (poor perfusion) found in the posterior mandible and ramus.¹⁵
As patients with complete maxillary denture and bilateral distal-extension mandibular removable partial dentures progressively lose bone in the posterior mandible, the lower denture bases gradually sink and a posterior open bite develops. When patients’ complete maxillary and partial mandibular dentures are adjusted routinely, the development of the posterior open bite is less severe.¹ When patients do not return for follow-up care and/or the mandibular removable partial denture is not well designed, relined, or maintained, a lack of posterior occlusal contacts causes an eventual and progressive shift of masticatory function to anterior segments of jaws.⁵
Subsequently, two important CS features usually develop. The first is hypertrophy of the anterior mandible with anterior hyperfunction. Anterior teeth are not designed for heavy occlusal load. Posterior reduction of function (posterior hypofunction) leads to anterior increase in function and subsequently hypertrophy of anterior mandibular bone to accommodate it. Anterior mandibular teeth take over function of mastication of practically the entire mandibular dentition. An adverse chronic pressure originating from the lower anterior teeth is directed toward the anterior portion of the unsupported maxillary denture. This repetitive force inevitably causes considerable resorption of the premaxillary alveolar bone. Heavy function, unusual in the anterior regions of the jaws, is known in the CS literature as anterior hyperfunction,^16,17 which explains the other commonly used term for the syndrome, anterior hyperfunction syndrome.^6,8,16,17
As both anterior maxillary atrophy and anterior mandibular hypertrophy develop, the entire anterior jaw complex progressively rotates clockwise (autorotation), leading to eventual unesthetic submergence of maxillary anterior denture teeth underneath the upper lip and abnormal exposure of mandibular anterior natural teeth from and above the vermilion border of the lower lip. Chronic occlusal trauma from the incisal edges of mandibular anterior teeth also often causes “flabby” and “fibrous” soft-tissue changes of the anterior palate, commonly described in the literature as papillary hyperplasia.^1,5,6The hyperplastic tissues in the region can be extensive and may compromise support and retention of a complete maxillary denture.
The second important symptom in CS cases is posterior maxillary hypertrophy and enlargement of maxillary tuberosities. In his original article,¹ Kelly suggested its origin from a “negative pressure” from underneath the denture related to presence of a posterior palatal seal. Today, it is attributed to a slow resorption of posterior mandibular bone, with reduction of alveolar ridge height and progressive sinkage (down migration) of the mandibular partial denture. The ensuing chronic posterior open bite seems to be responsible for hypertrophy of posterior maxillary alveolar bone with tuberosities in an attempt to preserve the vertical occlusal functional relationship. If the posterior maxilla has a remaining tooth or teeth, this bone hypertrophy usually occurs at the same time as tooth/teeth super-eruption. In most clinical cases with a lack of opposing dentition, both the teeth and underlying bone react simultaneously: teeth super-erupt and bone develops hypertrophy. In patients with CS, this phenomenon is unique and can occur in both the anterior and posterior regions of the jaws. In anterior segments of the jaws, lack of maxillary teeth (especially in the presence of anterior hyperfunction) leads to extrusion of mandibular teeth with simultaneous mandibular alveolar hypertrophy. In posterior segments of the jaws, an opposite process develops. A non-use atrophy of the mandibular edentulous bone with increasing posterior open bite is responsible for hypertrophy of posterior maxillary alveolar bone and super-eruption of teeth, if present.
Wolff’s law can give the best explanation for bone remodeling changes that occur in CS. It states that “bone, either normal or abnormal, will develop the structure most suited to resist those forces acting on it.”¹⁸ In other words, bone is deposited and resorbed in accordance with the stresses placed upon it. Recent experimental research has indicated that bone resorption is a pressure-regulated phenomenon.¹⁹ Both bone atrophy and hypertrophy are opposite processes of the bone remodeling process, and their development in the stomatognathic system appears to be proportional to a degree of occlusal stress.
Resorption of both anterior maxillary and posterior mandibular edentulous alveolar ridges leads to a progressive collapse of the vertical dimension of occlusion (anterior and posterior vertical occlusal heights). The mandible moves forward, causing a relative (pseudo) mandibular prognathism. An overprojected and up-rotated chin point and a collapsed lower facial height are associated with the altered facial esthetics seen in advanced CS cases. In some patients, not all symptoms are present or obvious. Two symptoms that are consistently present and distinguish CS cases from all other dental conditions are resorption of anterior maxilla and posterior open bite (loss of posterior occlusion). Figure 1 demonstrates the 10 most common CS symptoms and their interrelationships.
1

Treatment Options
Because of the complexities of CS, a team of dental professionals should be involved in the treatment process of patients with this oral condition. Kelly¹ emphasized prevention as the best possible treatment. He stated that the clinician should do everything possible to prevent the unfavorable combination of removable dental prostheses that include a complete maxillary denture and distal extension mandibular partial denture. Frequent relining of ill-fitting dentures slows down but does not stop the development of CS.
If conventional denture treatment is the only one selected by the patient, CS symptoms can be postponed through the use of a properly designed class I mandibular removable partial denture with equal redistribution of occlusal stresses over the hard and soft tissues of the entire dentition that maintains posterior function with maximal support and stability from the retromolar pads and buccal shelves.^20,21 A meticulous follow-up care and maintenance protocol is important.
Jameson and others^16,17,22,23 noticed avoidance of anterior hyperfunction should be the main emphasis of treatment directed at improving stability of removable dentures. Jameson advocated “linear occlusion,” or the occlusal arrangement of artificial teeth, as viewed in the horizontal plane, with a straight, long, narrow occlusal table of the mandibular posterior artificial teeth. He also stressed the importance of reducing the anterior incisal length for protrusive clearance. Although this prosthetic technique could improve the stability of dentures, it does not address endosseous bone loading (EBL) and prevention of bone resorption. Directing treatment toward the retention of lower posterior teeth “as abutments by means of endodontic and periodontic techniques” was emphasized by both Kelly¹ and Jameson.^16,17,22Mandibular overdentures retained on natural posterior roots with stud-type abutments can allow preservation of posterior alveolar bone and occlusion. This treatment approach does not stop bone resorption completely because the denture bases remain supported by mucosal tissues. In addition, in many cases, it is not possible to keep anterior incisor teeth or posterior roots because of the severity of their endodontic and/or periodontal conditions.
For some patients, mandibular anterior teeth can be treated with root canal therapy and have their clinical crowns shortened to place opposing maxillary incisors in a proper position. In advanced conditions of super-eruption, they need to be removed with vertical reduction of hypertrophic alveolar bone (alveoloplasty). A variety of surgical procedures may be needed, including excision of hyperplastic tissue from the anterior palate, reduction of hypertrophic bone of maxillary tuberosities and anterior mandible (alveolectomy), correction of premaxillary bone atrophy with bone grafting, subantral augmentation (sinus lift), and extraction of super-erupted (extruded) teeth. Occlusal considerations with correction of the occlusal plane always should be a part of the comprehensive treatment for CS.
Both implant-retained and implant-supported prostheses have become increasingly popular in the past 30 years and have been proven to be a successful prosthetic rehabilitation for partially and completely edentulous maxilla and mandible.^24-26 Implant-anchored prostheses have no inherent mobility associated with traditional root overdentures. These prostheses also demonstrate tremendous retention, improved stability, and ensure the endosseous bone loading that is so important for bone preservation.Implant-borne prostheses provide system rigidity with solid posterior contacts and preserved posterior occlusion, an imperative factor in CS cases.
At the same time, it is well documented in the literature^27-32 that full mandibular implant-retained or supported prostheses based on four to six anteriorly placed implants against a complete maxillary denture provoke an extensive resorption of premaxillary bone that is comparable with resorption afflicted from natural mandibular anterior teeth. The cause is similar—anterior traumatic occlusion. Therefore, implant treatment of both the mandibular and maxillary arches needs to be considered to control CS-associated bone loss. By reinforcing the maxilla with implants, a compatible pair of implant-supported upper and lower prostheses can function in unison for an extended period.
Full-arch maxillary and mandibular reconstruction with endosseous dental implants (with or without previous alveolar bone grafting) should aim to develop a stable posterior occlusion, prevent anterior hyperfunction, and, hopefully, achieve an even distribution of masticatory force over the entire dentition. These conditions can provide long-lasting stability for patients with CS. Many standard prosthetic principles of treatment are applicable in CS cases, including protective occlusal scheme, cross-arch stabilization, appropriate anterior-posterior (A-P) implant spread, thoughtful prosthetic design with adequate metal support of acrylic portion and cleansable features of prostheses, and adequate esthetics and phonetics.

Conclusion
CS cases demonstrate bone remodeling changes that include atrophy and hypertrophy in certain regions of the jaws. Chronic occlusal pressure (overload) eventually leads to bone resorption in the anterior maxillary zone (premaxilla). In reverse, lack of function and loss of occlusion over time tend to promote super-eruptive forces from the opposing dentition, leading to bone hypertrophy that is usually present in regions of anterior mandible and posterior maxilla, including maxillary tuberosities. Loss of posterior occlusion (posterior open bite) and anterior maxillary bone resorption are the defining symptoms of CS.
Although a traditional prosthetic approach with a complete maxillary denture and a bilateral-distal extension mandibular partial denture remains in use, osseointegrated implant-retained and especially implant-supported prosthetic treatment has become the mainstream approach for patients with CS. Implant rehabilitation techniques applied for CS patients are directed toward the prevention of EBL and bone preservation, reversal of anterior occlusal trauma (anterior hyperfunction), and reestablishment of posterior occlusion. Complex CS cases often necessitate an interdisciplinary approach to care. Further prospective and retrospective studies are necessary to challenge and expand our current knowledge of CS, emphasize its prevention, and improve treatment protocols for this fascinating and complex dental condition.

References
1. Kelly E. Changes caused by a mandibular removable partial denture opposing a maxillary complete denture. J Prosthet Dent. 1972;27(2):140-150.
2. Kelly E. Changes caused by a mandibular removable partial denture opposing a maxillary complete denture. J Prosthet Dent. 2003;90(3):213-219.
3. The glossary of prosthodontic terms. J Prosthet Dent. 2005;94(1):10-92.
4. Oral implantology. Glossary of implant terms. J Oral Implantol. 2007;(suppl 1):2-14.
5. Shen K, Gongloff RK. Prevalence of the “combination syndrome” among denture patients. J Prosthet Dent. 1989;62(6): 642-644.
6. Palmqvist S, Carlsson GE, Owall B. The combination syndrome: a literature review. J Prosthetic Dent. 2003;90(3):270-275.
7. Attard NJ, Zarb GA. Implant prosthodontic management of partially edentulous patients missing posterior teeth: the Toronto experience. J Prosthet Dent. 2003;89(4):352-359.
8. Tolstunov L. Combination syndrome: classification and case report. J Oral Implantol. 2007;33(3):139-151.
9. Carlsson GE. Clinical morbidity and sequelae of treatment with complete dentures. J Prosthet Dent. 1998;79(1):17-23.
10. Atwood DA. Reduction of residual ridges: a major oral disease entity. J Prosthet Dent. 1971;26(3):266-279.
11. Tallgren A. The continuing reduction of residual alveolar ridges in complete denture wearers: a mixed-longitudinal study covering 25 years. J Prosthet Dent. 1972;27(2):120-132.
12. Bergman B, Carlsson GE. Clinical long-term study of complete denture wearers. J Prosthet Dent. 1985;53(1):56-61.
13. Campbell RL. A comparative study of the resorption of the alveolar ridges in denture-wearers and non denture-wearers. J Am Dent Assoc. 1960;60:143-153.
14. Józefowicz W. The influence of wearing dentures on residual ridges: a comparative study. J Prosthet Dent. 1970;24(2):137-144.
15. Tolstunov L. Implant zones of the jaws: implant location and related success rate. J Oral Implantol. 2007;33(4):211-220.

Ceramics: Rationale for Material Selection

2011-09-26T18:11:00.001+03:00

Many types of ceramic materials and processing techniques have been introduced throughout the years. As early as 1903, Charles Land patented all-ceramic restorations, using fired porcelains for inlays, onlays, and crowns.¹ Insufficient understanding about material requirements for survival in the oral environment, poor ceramic processing techniques, and the inability for adhesive cementation led to early catastrophic failure. Since then, all imaginable varieties of materials and techniques from very conservative ceramic restorations to very complex porcelain veneered of either metal or high-strength crystalline ceramics have been introduced and tried with varying levels of success.² The authors have previously published two detailed descriptions, or classification systems, for ceramics used in dentistry — one based on the microstructure of the material and the second on how the material is processed.³
There is considerable misinformation and a general lack of rational treatment planning guidelines published regarding the use of different ceramics in dentistry. The literature is replete with various accounts of clinical success and failures of all types of dental treatments. Sadowsky⁴ published a review of the literature covering treatment considerations using esthetic materials, eg, whether to use amalgam or composite and
the success rates of different treatments. No recent literature could be found presenting a thorough discussion of when to use the various ceramics, eg, when feldspathic porcelains should be used, when either pressed or machined glass-ceramics are appropriate, when different types of glass-ceramics should be employed, when a high-strength all-ceramic crown system of either alumina or zirconia is ideal, and when metal-ceramics are suitable. This article provides a systematic stepwise process in treatment planning ceramic materials and presents specific guidelines for the appropriate clinical conditions for applications of the various systems.

TREATMENT PHILOSOPHY
Before making any decision regarding the use of a material or technique, a dental practitioner must have a treatment philosophy based on current standards of care that consider the patient’s esthetic requirements. More importantly, this philosophy should be aimed at maintaining long-term biologic and structural health of the patient in the least destructive way.
Restorative or esthetic dentistry should be practiced as conservatively as possible. The use of adhesive technologies makes it possible to preserve as much tooth structure as feasible while satisfying the patient’s restorative needs and esthetic desires.⁵ The philosophy today is not to remove any healthy tooth structure unless absolutely necessary. This will reduce the dentist’s frustration when orthodontics would have been the ideal treatment. With restorations, clinicians should choose a material and technique that allows the most conservative treatment in order to satisfy the patient’s esthetic, structural, and biologic requirements and has the mechanical requirements to provide clinical durability. Each of these requirements could be the topics of individual articles.
There are four broad categories, or types of ceramic systems, of which to choose: Category 1: powder/liquid feldspathic porcelains; Category 2: pressed or machined glass-ceramics; Category 3: high-strength crystalline ceramics; and Category 4: metal-ceramics. Category 1 (porcelains) — the most translucent — can be used the most conservatively but is the weakest.^3,6 Category 2 (glass-ceramics) also can be very translucent but requires slightly thicker dimensions for workability and esthetics than Category 1. Although demonstrating progressively higher fracture resistance, Categories 3 and 4 are more opaque and, therefore, require additional tooth reduction that produces a less conservative alternative. Based on the treatment goal of being as conservative as possible, the first choice will always be porcelains, then glass-ceramics, followed by high-strength ceramics or metal-ceramics. The decision will be based on satisfying all the treatment requirements, ie, if the more conservative material can meet all the treatment requirements, then that is the ideal choice. The article will identify the clinical conditions in which treatment requirements dictate the use of a specific category.

SPACE REQUIRED FOR EStHETICS
The first consideration is the final 3-D position of the teeth, ie, smile design. The reader has several resources for smile design.^7,8 Second, the color change desired from the substrate (tooth) must be determined because this will dictate the restoration thickness. In general with porcelains, the dentist needs a porcelain thickness of 0.2 mm to 0.3 mm for each shade change (A2 to A1 or 2M1 to 1M1). For example, A3 to A0 would require a veneer 0.6-mm to 0.9-mm thick. Glass-ceramics need the same space requirements as porcelain for effective shade change; however, the authors find it difficult to work with this category and to produce the best esthetic results if the material is less than 0.8 mm. High-strength all-ceramic crowns require a thickness of 1.2 mm to 1.5 mm, depending on the substrate color; metal-ceramics need a thickness of at least 1.5 mm to create lifelike esthetics. With that in mind, a diagnosis based on tooth position and color change will direct treatment planning, as well as the final decision regarding tooth preparation design (ie, total tooth structure reduction) and whether a combination of orthodontic treatment is required to facilitate a more conservative, esthetic outcome.

CLINICAL PARAMETERS TO EVALUATE
When the 3-D smile design is completed, color change assessed, and adjunctive therapy finished to create an environment that will allow the least removal of healthy tooth structure, an evaluation of each tooth is needed for ascertaining which ceramic system and technique is most suitable. The evaluation of individual teeth for specific material selection involves assessing four environmental conditions in which the restoration will function.

1. Substrate
The first consideration is evaluating the substrate to which the material will be attached fig 1. Is it enamel? How much of the bonded surface will be enamel? How much enamel is on the tooth? Is it dentin? How much of the bonded surface will be dentin? What type of dentin will the restoration be bonded to (ie, tertiary or sclerotic dentin exhibits very poor bond strength, and bonding to this type of dentin should be avoided when possible)? Is it a restorative material (eg, composite, alloy)? These questions should be addressed for each tooth to be restored because this will be one major parameter for material selection.
It is generally understood and accepted that predictable and high bond strengths are achieved when restorations are bonded to enamel, given the fact that the stiffness of enamel supports and resists the stresses placed on the materials in function. It is equally understood that bonding to dentin surfaces — as well as to composite substrates — is less predictable given the flexibility of these substrates. The more stress placed on the bonds between dentin and composite substrates and the restoration, the more damage is likely to occur to the restoration and underlying tooth structure. Therefore, because enamel is significantly stiffer than either dentin or composite and much more predictable for bonding, it is the ideal substrate for bonded porcelain restorations.

Figure 1 Image of the prepared tooth. Significant dentin is exposed. The proposed length flexure and tensile stress risk is at least medium and the restoration thickness would be at least 0.9 mm. This was noted in the chart.

2. Flexure Risk Assessment
Next is the flexure risk assessment. Each tooth and existing restoration is evaluated for signs of past overt tooth flexure. Signs of excessive tooth flexure can be excessive enamel crazing (fig 2), tooth and restoration wear, tooth and restoration fracture, microleakage at restoration margins, recession, and abfraction lesions. Often, the etiology is multifactorial and controversial. However, if several of these conditions exist, there is an increased risk of flexure on the restorations that are placed, which may overload weaker materials. Evaluation of this possibility is also based on the amount of remaining tooth structure. The more intact the enamel is, the less potential for flexure. The amount of tooth preparation can directly affect tooth flexure and stress concentration. There is much potential subjectivity in any observational assessment of clinical conditions; however, an assessment of flexure potential for each tooth to be restored is needed. A subjective assignment of Low, Medium, or High Risk for flexure is based on the evaluated parameters, as outlined below.
Low Risk: There is low wear, minimal-to-no fractures or lesions in the mouth, and a reasonably healthy oral condition.
Medium Risk: Signs of occlusal trauma are present; mild-to-moderate gingival recession exists, along with inflammation; bonding mostly to enamel is still possible; and there are no excessive fractures.
High Risk: Occlusal trauma from parafunction is evident, more than 50% dentin exposure exists, there is significant loss of enamel due to wear of 50% or more, and porcelain must be built up more than 2 mm.

Figure 2 Image demonstrating excessive enamel crazing, leakage, and staining. Flexure, tensile, and shear risks would be medium to high. The substrate would depend on preparation

3. Excessive Shear and Tensile Stress Risk Assessment
The third parameter is the risk (or amount) of ongoing shear and tensile stresses that the restoration will undergo, because the prognosis is more guarded for specific materials. All types of ceramics (especially porcelains) are weak in tensile and shear stresses.⁹ Ceramic materials perform best under compressive stress. If the stresses can be controlled, then weaker ceramics can be used, eg, bonded porcelain to the tooth. The same parameters are evaluated, similar to flexure risk, eg, deep overbites and potentially large areas where the ceramic would be cantilevered fig 3. If a high-stress field is anticipated, stronger and tougher ceramics are needed; if porcelain is used as the esthetic material, the restoration design should be engineered with such support (usually a high-strength core system) that it will redirect shear and tensile stress patterns to compression. To achieve that, the substructure should reinforce the veneering porcelain by using the reinforced porcelain system, which is generally accepted in the literature as a metal-ceramic concept.¹⁰ The practitioner can assess and categorize Low, Medium, or High Risk for tensile and shear stress based on the parameters and symptoms mentioned above.

Figure 3 Image demonstrating a deep overbite in which shear and tensile stresses would be at least medium. Bonded porcelain would require maintenance of enamel and an occlusal strategy to reduce leverage on the teeth

4. Bond/Seal Maintenance Risk Assessment
The fourth parameter is the risk of losing the bond or seal of the restoration to the tooth over time. Glass matrix materials, which are the weaker powder/liquid porcelains, and the tougher pressed or machined glass-ceramics absolutely require maintenance of the bond and seal for clinical durability.^11,12 Due to the nature of the glass matrix materials and absence of a core material, the veneering porcelains are much more susceptible to fracture under mechanical stresses. Therefore, a good bond in combination with a stiffer tooth substructure (eg, enamel) is essential to reinforce the restoration. If the bond and seal cannot be maintained, then high-strength ceramics or metal-ceramics are the most suitable because these materials can be placed using conventional cementation techniques. Clinical situations in which the risk is higher for bond failure are: 1) moisture control problems; 2) higher shear and tensile stresses on bonded interfaces; 3) variable bonding interfaces (eg, different types of dentin); 4) material and technique selection of bonding agents (ie, as dictated by such clinical situations as the inability to achieve proper isolation for moisture control to enable the use of adhesive technology); and 5) the experience of the operator fig 4. An assignment of Low, Medium, or High Risk for bond and seal failure is based on the evaluated parameters.

Figure 4 Image of a preparation with a poor substrate and subgingival margins where maintaining the seal would be difficult. High-strength ceramics or metal-ceramics would be indicated.

CATAGORY 1 CERAMICS (POWDER/LIQUID PORCELAINS)
Guidelines
Bonded pure porcelain restorations are ideal as the most conservative choice but are the weakest materials and require specific clinical parameters to be successful.¹³ Many good materials and techniques are available for bonded porcelain (eg, Creation, Jensen Dental, www.jensendental.com; Cermaco® 3, Dentsply, www.dentsply.com; EX-3, Noritake, www.noritake-dental.co.jp). The authors use Vita® VM 13 (Vita Zahnfabrik, www.vita-zahnfabrik.com) when 3-D master shades are taken and Halo (Shofu, www.shofu.com) when classic shades are taken. When following clinical parameters and guidelines at the UCLA Center for Esthetic Dentistry, the authors have observed similar success rates with these materials when compared with porcelain-fused-to-metal (PFM) materials (ie, less than a 1% fracture rate if all parameters are followed) fig 5 and 6

Figure 5 Image of minimal preparations prior to application of the bonded porcelain.

Figure 6 Two-year postoperative image of very conservative Category 1 bonded porcelain restorations.

.
Esthetic Factors
Space requirements for shade change: 0.2 mm to 0.3 mm for each shade change.
Environmental Factors
1. Substrate condition: A rate of 50% or more remaining enamel is on the tooth, 50% or more of the bonded substrate is enamel, and 70% or more of the margin is in enamel. These percentages are subjective assessments based on an overall evaluation of all parameters affecting the teeth to be restored and may influence material selection. If bonding to some dentin substrate, the dentin should be mostly unaffected and superficial because sclerotic dentin exhibits very poor bond strength.

2. Flexure risk assessment: A higher-risk and more guarded prognosis is presented when bonding to dentin. Due to dentin’s flexible nature, avoiding the use of low-fracture resistance restorative materials is recommended; therefore, the presence of a higher percentage of enamel (ie, at least 70% in high-stress areas such as the margins) is recommended when restoring using powder/liquid materials (Category 1). By increasing the presence of enamel, the prognosis is improved. Depending on the dentin/enamel ratio, the risk can be assessed between low to moderate.

3. Tensile and shear stress risk assessment: Low-to-low/moderate risk. Large areas of unsupported porcelain, deep overbite or overlap of teeth, bonding to more flexible substrates (eg, dentin and composite), bruxing, and more distally placed restorations increase the risk of exposure to shear and tensile stresses.

4. Bond/seal maintenance risk assessment: Absolute low risk of bond/seal failure.
Summary: 1) Generally indicated for anterior teeth; 2) occasional bicuspid use and rare molar use would be acceptable only with all parameters at the least-risk level. Category 1 materials are ideal in cases with significant enamel on the tooth and generally with low flexure and stress risk assessment. These materials absolutely require long-term bond maintenance for success.

CATEGORY 2: CERAMICS (GLASS_BASED PRESSED OR MACHINABLE MATERIALS)
Guidelines
Glass-ceramic pressable materials, such as IPS Empress® (Ivoclar Vivadent, www.ivoclarvivadent.us) and Authentic® (Jensen Dental), and the higher-strength IPS e.max® (Ivoclar Vivadent) materials can be used in any of the clinical situations as Category 1 materials. Machinable versions of glass- ceramic material, such as Vitablocs Mark II® (Vident, www.vident.com), IPS Empress CAD, and IPS e.max CAD, can be used interchangeably with the pressed versions. Monolithic IPS e.max, due to its high strength and fracture toughness, has shown promise as a full-contour, full-crown alternative, even on molars.¹⁴ Glass-ceramics can also be used in clinical situations when higher risk factors are involved. Other than certain risk factors (see below) that would limit their use, these materials can be difficult to use when there is less than 0.8 mm in thickness, except at marginal areas. They can gradually thin to a margin of approximately 0.3 mm. All things being equal, if the restoration is still a Category 1 clinical situation and there is more than 0.8 mm of working space, glass-ceramics should be considered due to their increased strength and toughness, as well as the presence of sufficient room to achieve the desired esthetics.
Esthetic Factors
Space requirements for workability and shade change: 0.8 mm of minimum working thickness and 0.2 mm to 0.3 mm for each shade change.

Environmental Factors

1. Substrate condition: Less than 50% of the enamel is on the tooth, less than 50% of the bonded substrate is in the enamel, and 30% or more of the margin is in the dentin.
2. Flexure risk assessment: Medium for Empress, Vitablocs Mark II, and Authentic-type glass-ceramics or layered IPS e.max. In cases in which flexure risk assessment is medium to high (and full-crown preparation is not desirable), the authors have found in their clinical trials that monolithic IPS e.max has been 100% successful for as long as 30 months in service. All glass-ceramic restorations, including IPS e.max, were adhesively bonded in their samples.
3. Tensile and shear stress risk assessment: Medium for Empress, Vitablocs Mark II, and Authentic-type glass-ceramics or layered IPS e.max. Medium to medium/high for bonded monolithic IPS e.max.
4. Bond/seal maintenance risk assessment: Low risk of bond/seal failure for Empress, Vitablocs Mark II, and Authentic-type glass-ceramics or layered IPS e.max. Medium for monolithic IPS e.max.
Summary: Pressed or machined glass-ceramic material such as Empress, Vitablocs Mark II, and Authentic are indicated for thicker veneers, anterior crowns, and posterior inlays and onlays (Fig 7 and 8) in which medium or lower flexure risks and shear and tensile stress risks are documented (fig 9 and 10). Also, they are indicated only in clinical situations in which long-term bond and seal can be maintained. IPS e.max (fig 11 and 12), which is a different type of glass-ceramic that has higher toughness, is also indicated for the same clinical situations as the other glass-ceramics but can be extended for single-tooth use in higher-stress situations (as in molar crowns). This is provided it is used in a full-contour monolithic form and cemented with a resin cement.

Figure 7 Preoperative photograph of an inlay in tooth No. 18 and an onlay on tooth No. 19

Figure 8 Postoperative photograph showing a nonlayer material in use.

Figure 9 Preoperative photograph of a case requiring significant lengthening. There is at least medium risk of flexure and unfavorable stress, and some of the substrate would be dentin. Thus, Category 1 materials were eliminated as a choice.

Figure 10 Postoperative photograph after Category 2 materials were applied, with minimal porcelain layering in the incisal one third.

Figure 11 Preoperative photograph of a case in which the patient refused surgery and orthodontics. The treatment goal was to do minimal preparation and use a tough material due to the general medium-to-high risk in every area; obtaining a seal was possible

Figure 12 Postoperative photograph with bonded full-contour restorations in place on the posterior teeth and incisally layered anterior teeth.

CATEGORY 3 CERAMICS (HIGH-STRENGHT CRYSTALINE CERAMICS)
Guidelines
Mostly all-crystalline materials (eg, In-Ceram®, Vita) are used for core systems to replace metal that would then be veneered with porcelain. Alumina-based systems, eg, In-Ceram, Procera® (Nobel Biocare, www.nobelbiocare.com), were first on the market but are now generally being replaced with zirconia systems. Alumina systems have been shown to be very clinically successful for single units, with a slightly increased risk in the molar region.^15,16 They can be recommended for any single-unit anterior or bicuspid crown (fig 13 and 14). The authors have observed a slight increase in failure with conventional cements. For example, after using alumina restorations for many years at the UCLA Center for Esthetic Dentistry, the authors observed that at between 8 and 10 years, the failure rate doubled to approximately 2%, with those failures being core fractures necessitating replacement. Their suggestion for alumina core restorations is either a resin-modified glass-ionomer luting cement (eg, Fuji PLUS™ GC America, www.gcamerica.com; RelyX™ Luting, 3M ESPE, www.3mespe.com) or a resin cement. For zirconia core systems (eg, Vita YZ, Vident, www.vident.com; Procera® Zirconia, Nobel Biocare, www.nobelbiocare.com; Lava™, 3M ESPE), the authors have not experienced core fracture but have seen problems with chipping of porcelain. White and McLaren¹⁷ found that a special slow-cool thermal cycle minimizes the stress in the porcelain and porcelain/zirconia interface. Clinically, because the authors of this current article have been using the altered firing schedules, their replacement rate for chipping has been reduced by less than 1%.

Figure 13 Preoperative photograph of an old, unesthetic PFM

Figure 14 Postoperative photograph of a high-alumina crown system

Esthetic Factors
Space requirements for workability and maximum esthetics: 1.2-mm minimum working thickness and 1.5 mm ideal if masking.
Environmental Factors
1. Substrate condition: Substrate is not critical because the high-strength core supports the veneering material.
2. Flexure risk assessment: High or below. For high-risk situations, the core design and structural support for porcelain become more critical.
3. Tensile and shear stress risk assessment: High or below. Note: For high-risk situations, the core design and structural support for porcelain become more critical. Preparations should allow for a 0.5-mm core plus 1 mm of porcelain to ensure the best esthetic results. In addition, there should not be more than 2 mm of unsupported occlusal or incisal porcelain; the restoration core should be built out to support marginal ridges. For higher-risk molar regions, it is more ideal to use zirconia cores vs alumina cores, provided the current firing parameters are followed. Full-contour zirconia restorations (eg, Prettau Zirconia, Zirkozahn, www.zirkonzahn.com; BruxZir®, Glidewell Laboratories, www.glidewelldental.com) have been recommended for high-risk molar situations. Failure of these restorations would not be an issue; some preliminary concern involves wear of the opposing dentition with full-contour zirconia.¹⁸ No clinical data could be found to confirm or refute this. Clinically, only full-contour zirconia against full-contour zirconia in the molar region should be considered when no other clinical option is viable.
4. Bond/seal maintenance risk assessment: If the risk of obtaining or losing the bond or seal is high, then zirconia is the ideal all-ceramic to use.
Summary: High-strength ceramics (specifically zirconia) is indicated when significant tooth structure is missing, an unfavorable risk for flexure and stress distribution is present, and it is impossible to obtain and maintain the bond and seal (eg, most posterior full-crown situations with subgingival margins) fig 15 and 16.

Figure 15 Preoperative photograph of an old PFM. The patient was unhappy with the opacity and metal display at the margin. Category 3 or 4 material is required for this case

Figure 16 Postoperative view.

.
CATEGORY 4 CERAMICS (METAL-CERAMICS)
Guidelines
For almost half a century, metal-ceramics have been the standard for esthetic full-crown restorations. Generally, they have the same indications as Category 3 zirconia-based restorations. With metal-ceramics, manufacturers have eliminated the complications throughout the years; these materials do not have the same thermal firing sensitivity as zirconia does. However, anterior teeth metal-ceramics need to be approximately 0.3 mm thicker to have the same esthetics as properly designed zirconia/porcelain crowns.
Esthetic Factors
1. Work space requirements: 1.5 mm to 1.7 mm for maximum esthetics.
2. Substrate condition: The substrate is not as critical because a metal core supports the veneering material.
3. Flexure risk assessment: High or below. For high-risk situations, the core design and structural support for porcelain become more critical.
4. Tensile and shear stress risk assessment: High or below. For high-risk situations, the core design and structural support for porcelain become more critical.
5. Bond/seal maintenance risk assessment: If the risk of obtaining or losing the bond or seal is high, then metal-ceramics are an ideal choice for a full-crown restoration.
Summary: Metal-ceramics are indicated in all full-crown situations, especially when all risk factors are high (figure 17).

Figure 17 Postoperative photograph of teeth Nos. 18 to 20 in a case with subgingival margins. Photograph courtesy of Yi-Yuan Chang.

CONCLUSION
This article presented a systematic process of clinical evaluation and rationale for material selection. The most important point is the most conservative restoration should be done if the clinical criteria are met, eg, a full-coverage crown or deep-cut glass-ceramic restoration should not be performed when a more conservative Category 1 porcelain restoration is indicated.
REFERENCES
1. Land CH. Porcelain dental art. Dent Cosmos. 1903;65:615-620.
2. Della Bona, Kelly JR. The clinical success of all-ceramic restorations. J Am Dent Assoc.2008;139(suppl);8S-13S.
3. McLaren EA, Cao PT. Ceramics in dentistry—part I: classes of materials. Inside Dentistry. 2009:5(9)94-103.
4. Sadowsky SJ. An overview of treatment considerations for esthetic restorations: a review of the literature. J Prosthet Dent. 2006;96(6):433-442.
5. Strassler HE. Minimally invasive porcelain veneers: indications for a conservative esthetic dentistry treatment modality. Gen Dent. 2007;55(7):686-712.
6. Giordano R. A Comparison of all-ceramic systems. J Mass Dent Soc. 2002;50(4):16-20.
7. McLaren EA, Cao PT. Smile analysis and esthetic design: “in the zone.” Inside Dentistry. 2009;5(7):44-48.
8. Chiche G, Pinault A. Esthetics of Anterior Fixed Prosthodontics. Hanover Park, IL: Quintessence Publishing. 1994:13-32.
9. Hondrum SO. A review of the strength properties of dental ceramics. J Prosthet Dent. 1992;67(6):859-865.
10. Shoher I, Whiteman A. Reinforced porcelain system: a new concept in ceramometal restorations. J Prosthet Dent. 1983;50(4):489-496.
11. Malament KA. Considerations in posterior glass-ceramic restorations. Int J Periodontics Restorative Dent.1988;8(4):32-49.
12. Malament KA, Socransky SS, Thompson V, et al. Survival of glass-ceramic materials and involved clinical risk: variables affecting long-term survival. Pract Proced Aesthet Dent. 2003(suppl):5-11.
13. Friedman MJ. A 15-year review of porcelain veneer failure—a clinician’s observations. Compend Contin Educ Dent. 1998;19
(6):625-638.

Ceramics Overview: Classification by Microstructure and Processing Methods

2011-09-26T13:53:00.002+03:00

Many different ceramic systems have been introduced in recent years for all types of indirect restorations from conservative no-preparation veneers to multiple-unit posterior fixed partial dentures (FPDs) and everything in between. Knowing the various nuances of materials and processing systems is overwhelming and can be confusing. Using a classification of the microstructural components of ceramics, this article covers the types of ceramics available. A second simpler classification system established on how the ceramics are processed will provide the main guidelines for their use.
The term ceramic is derived from the Greek word "keramos," which means "potter" or "pottery." This is related to a Sanskrit term meaning "burned earth," because the basic components were clays from the earth that were heated to form pottery. Ceramics are nonmetallic inorganic materials and refer to numerous materials, including metal oxides, borides, carbides, and nitrides, as well as complex mixtures of these materials.¹ Their structure is crystalline, displaying a regular periodic arrangement of the component atoms, and may exhibit ionic or covalent bonding. Although ceramics can be very strong, they are also extremely brittle and will catastrophically fail after minor flexure. Thus, these materials are strong in compression but weak in tension.
Contrast that to metals, which are nonbrittle (display elastic behavior) and ductile (display plastic behavior). This is because of the nature of the interatomic bonding, which is called metallic bonds. Defining these bonds is a cloud of shared electrons that can easily move when energy is applied. This is what makes most metals great conductors. Ceramics can be very translucent to very opaque. In general, the glassier the microstructure (ie, noncrystalline), the more translucent the ceramic will appear; the more crystalline, the more opaque. Other contributory factors to translucency include particle size, particle density, refractive index, and porosity, just to name a few.
There are many clinical and technical aspects that are important for success with all-ceramic materials but are not as critical with metal-based restorations and not possible to cover here. A basic clinical use guide is shown( in table 1). The reader is advised that significant knowledge and training in these areas are requisites for technical success with all-ceramic materials.

The Different Ceramics Used in Dentistry

The term ceramic technically refers to a crystalline material. Porcelain is a mixture of glass and crystal components. A noncrystalline-containing material is simply a glass. However, dentistry typically refers

to all three basic materials as dental ceramics. How ceramics are classified can be confusing. Ceramics can be divided by their microstructure (ie, amount and type of crystalline phase and glass composition), processing technique (powder/liquid, pressed, or machined), and clinical application. To provide the reader with a better understanding of ceramics, the authors give a classification based on the microstructure of ceramics, with the inclusion of how the ceramics are processed, which affects durability.

Microstructural Classification

At a microstructural level, ceramics can be defined by their composition of glass-to-crystalline ratio. There can be infinite variability of the microstructures of materials; however, they can be divided into four basic compositional categories with a few subgroups:

Composition Category 1: Glass-based systems (mainly silica)
Composition Category 2: Glass-based systems (mainly silica) with fillers usually crystalline (typically leucite or a different high-fusing glass)
Composition Category 3: Crystalline-based systems with glass fillers (mainly alumina)
Composition Category 4: Polycrystalline solids (alumina and zirconia)

Composition Category 1: Glass-based Systems, Amorphous Glass

Glass-based systems are made from materials that contain mainly silicon dioxide (also known as silica or quartz), which have various amounts of alumina. Naturally occurring aluminosilicates, which contain various quantities of potassium and sodium, are known as feldspars. Feldspars are modified in different ways to create the glasses used in dentistry. Synthetic forms of aluminosilicate glasses are also manufactured for dental ceramics. The authors found no documented references that showed naturally occurring aluminosilicate glasses perform better or worse than synthetic even though there have been claims to the contrary. These materials were first used in dentistry to make porcelain dentures.
Mechanical properties are low, with flexural strength usually from 60 MPa to 70 MPa. Thus, they tend to be employed as veneer materials for metal or ceramic substructures, as well as for veneers, using either a refractory die technique or platinum foil. The microstructure of a glass is shown in fig 1. This is a scanning electron micrograph of an acid-etched glass surface. The holes indicate a second glass, which was removed by the acid. The veneer restoration uses a glassy porcelain fig 2 and 3.
fig 1
fig 2
fig 3

Composition Category 2: Glass-based Systems with Crystalline Second Phase, Porcelain

This category has a large range of glass-crystalline ratios and crystal types, so much so that the authors subdivided this category into three groups. The glass composition is similar to the pure glass Category 1. The difference is varying amounts of crystal types have either been added to or grown in the glassy matrix. The primary crystal types today are either leucite, lithium disilicate, or fluorapatite. Leucite is created in dental porcelain by increasing the K₂O (potassium oxide) content of the aluminosilicate glass. Lithium-disilicate crystals are made by adding Li₂O (lithium oxide) to the aluminosilicate glass. It also acts a flux, lowering the melting temperature of the material.
These materials have also been developed into fine-grain machinable blocks—Vitablocs Mark II (Vident, vident.com) for use with CEREC^® computer-aided design/computer-aided manufacturing (CAD/CAM) system (Sirona, www.sirona.com). Sirona CERECblocs are fabricated by Vita using the Vitablocs Mark II powders; however, Sirona has a different shade system. This material is the most successfully documented machinable glass for the fabrication of inlays and onlays with all studies showing a less than 1% per year failure rate, which compares favorably with metal-ceramic survival data.^2-7 A pre-manufactured block has no residual porosity in the finished core that could act as a weak point and lead to catastrophic failure.

Subcategory 2.1

Low-to-moderate leucite-containing feldspathic glass: Even though other categories have a feldspathic-like glass, these materials have been called feldspathic porcelains by default. Leucite may alter the coefficient of thermal expansion (CTE), as well as inhibit crack propagation, thereby improving the material's strength. The amount of leucite may be adjusted in the glass based on the type of core and required CTE. These materials are the typical powder/liquid materials used to veneer core systems and are also ideal for porcelain veneers. The original materials had a fairly random size and distribution of leucite crystals with the average particle size of approximately several hundred microns. This random distribution and large particle size contributed to the material's low-fracture resistance and abrasive properties relative to enamel.⁸ Newer generations of materials have been developed with much finer leucite crystals (10 µm to 20 µm) and very even particle distribution throughout the glass. These materials are less abrasive and have much higher flexural strengths.⁹ In fig 4 a scanning electron micrograph (SEM) of a typical feldspathic porcelain reveals a glass matrix surrounding leucite crystals. These materials are most commonly used as veneer porcelains for metal-ceramic restorations fig 5.
fig 4
fig 5

Subcategory 2.2

High-leucite (approximately 50%)-containing glass, glass-ceramics: The microstructure of these materials consists of a glass matrix surrounding a second phase of individual crystals. The material starts as a homogeneous glass. A secondary heat treatment nucleates and grows crystals, which gives this class improved mechanical and physical properties due to the physical presence of the crystals and generation of compressive stress around the crystals. Glass-ceramics may be ideally suited for use as dental restorative materials and generally have improved mechanical and physical properties, such as increased fracture resistance, improved thermal shock resistance, and resistance to erosion. Improvements in properties depend on the interaction of the crystals and glassy matrix, as well as on the crystal size and amount. Finer crystals generally produce stronger materials. Glass-ceramics are in widespread use for cookware, missile nose cones, and even heat shields on space vehicles. They may be opaque or translucent depending on the chemical composition and percent crystallinity. A fundamental method of improving strength and fracture resistance is to add a second phase to a glass material—dispersion strengthening. The crystals may act as roadblocks to cracks. A crack growing from a defect must go through or around the crystal; this diverts some energy from the propagating crack and may stop it entirely. Thus, the restoration may continue to function instead of cracking in half. In addition to the "roadblock" effect, compressive stresses around the growing crystals may help pin cracks and further enhance fracture resistance.
The most widely used version is the original pressable ceramic Empress^® (Ivoclar Vivadent,www.ivoclarvivadent.com) (fig 6-8). A number of pressable materials with properties and microstructure similar to Empress are available. These include Finesse^® (DENTSPLY,www.dentsply.com), Authentic^® (Jensen, www.jensendental.com), PM™9 (Vita, www.vident.com), and OPC (Pentron, www.pentronceramics.com) A machinable version Empress CAD (Ivoclar) designed for both CEREC^® (Sirona, www.sirona.com) and E4D^® CAD/CAM (D4D Technologies, www.e4dsky.com) systems for high-leucite ceramics has performed well clinically when used for posterior inlays and onlays, as well as anterior veneer and crown restorations.^9-14 Paradigm™ C porcelain block (3M ESPE, www.3mespe.com) has a similar properties. Machinable and pressable systems have much higher fracture resistance than powder/liquid systems and have shown excellent clinical results for posterior inlay and onlay applications and anterior veneer and crown restorations.
6
7
8

Subcategory 2.3

Lithium disilicate glass-ceramics: This is a true glass-ceramic introduced initially by Ivoclar as Empress II (and now in the form of IPS e.max^® pressable and machinable ceramics). Increasing the crystal content to approximately 70% and refining the crystal size improved flexural strength. The glass matrix consists of a lithium silicate with micron-size lithium-disilicate crystals in between, which are submicron lithium-orthophosphate crystals (Fig 9-11). This creates a highly filled glass matrix. A veneer porcelain consisting of fluorapatite crystals in an aluminosilicate glass may be layered on the core to create the final morphology and shade of the restoration. The shape and volume of crystals increase the flexural strength to approximately 360 MPa, or about three times that of Empress.^15-19This material can be translucent even with the high crystalline content; this is due to the relatively low refractive index of the lithium-disilicate crystals. The material is translucent enough that it can be used for full-contour restorations or for the highest esthetics and can be veneered with special porcelain. Veneer porcelain consisting of fluorapitite crystals in an aluminosilicate glass may be layered on the core to create the final morphology and shade of the restoration. Fluorapitite is a fluoride-containing calcium phosphate, Ca₅(PO₄)₃F. The fluorapitite crystals contribute to the veneering porcelain's optical properties and CTE, so it matches the lithium-disilicate pressable or machinable material. Both the veneering and lithium-disilicate materials are etchable due to the glassy phase. Initial clinical data for single restorations are excellent with this material, especially if it is bonded.²⁰ A material with similar properties and structure called 3G OPC is available as a pressable glass-ceramic from Pentron.
9
10
11

Composition Category 3: Interpenetrating Phase Ceramics

In-Ceram^® (Vident, www.vident.com) consists of a family of all-ceramic restorative materials based on the same principle introduced in 1988. The family includes a range of strengths, translucencies, and fabrication methodology designed to cover the wide scope of all-ceramic restorations, including veneers, inlays, onlays, and anterior/posterior crowns and bridges. In-Ceram Spinell (alumina and magnesia matrix) is the most translucent with moderately high strength and used for anterior crowns. In-Ceram Alumina (alumina matrix) has high strength and moderate translucency and is used for anterior and posterior crowns. In-Ceram Zirconia (alumina and zirconia matrix) has very high strength and lower translucency and is used primarily for three-unit posterior bridges. In addition, these materials are supplied in a block form for producing milled restorations using a variety of machining systems.
In-Ceram is in a class called interpenetrating phase composites.²¹ They consist of at least two phases, which are intertwined and extend continuously from the internal to external surfaces (fig 12). This class has better mechanical and physical properties relative to the individual components; a tortuous route through alternating layers of both components is required in order for these materials to break.
12

Interpenetrating phase materials are generally fabricated by first creating a porous matrix; in the case of In-Ceram, it would be a ceramic "sponge." The pores are then filled by a second-phase material, lanthanum-aluminosilicate glass, using capillary action to draw a liquid or molten glass into all the pores to produce the dense interpenetrating material.
The system was developed as an alternative to conventional metal-ceramics and has met with great clinical success.^22,23 The system uses a sintered crystalline matrix of a high-modulus material (85% of the volume) in which there is a junction of the particles in the crystalline phase. This is different than glasses or glass-ceramic materials in that these ceramics consist of a glass matrix with or without a crystalline filler in which there is no junction of particles (crystals). Slip casting²⁴ may be used to fabricate the ceramic matrix, or it can be milled from a presintered block.²⁵ Flexural strengths range from 350 MPa for spinell, 450 MPa for alumina, and up to 650 MPa for zirconia. Several clinical studies support the use of In-Ceram Alumina for single units placed anywhere in the mouth. In-Ceram Alumina had the same survival rates as porcelain-fused-to-metal restorations up to the first molar, with a slightly higher failure rate for the second molar.^26-28 In-Ceram Zirconia should only be used on molars due to its very high opacity, which is not suitable for anterior esthetics. For anterior teeth, the alumina magnesia version of In-Ceram (called Spinell) is ideal due to its higher translucency (fig 13-15).
13
14
15

Composition Category 4: Polycrystalline Solids

Solid-sintered monophase ceramics are formed by directly sintering crystals together without any intervening matrix to form a dense, air-free, glass-free, polycrystalline structure. Several processing techniques allow the fabrication of either solid-sintered aluminous oxide (alumina, Al₂O₃) or zirconium oxide (Z_rO₂) framework. The first fully dense polycrystalline material for dental applications was Procera^® AllCeram alumina (Nobel Biocare, www.nobelbiocare.com), with a strength of approximately 600 MPa.²⁹ The alumina powder is pressed and milled on a die and sintered at about 1600°C, leading to a dense coping but with approximately 20% shrinkage (fig 16-18).
16
17
18

The use of what is commonly referred to in dentistry as zirconia has increased rapidly in the past few years. This is not pure zirconia; it is partially stabilized by the addition of small amounts of other metal oxides. Partially stabilized zirconia allows production of reliable multiple-unit all-ceramic restorations for high-stress areas, such as the posterior region of the mouth. Zirconia may exist in several crystal types (phases) depending on the addition of minor components, such as calcia (CaO), magnesia (MgO), yttria (Y₂O₃), and ceria (CeO₂). Specific phases are said be stabilized at room temperature by the minor components. Typically for dental applications, about 3 weight% of yttria is added to pure zirconia (fig 19- 21).
19
20
21

Zirconia has unique physical characteristics that make it twice as strong and tough as alumina-based ceramics. Values for flexural strength range from approximately 900 MPa to 1100 MPa.^30,31 There is no direct correlation between flexural strength (modulus of rupture) and clinical performance. Another important physical property is fracture toughness, which has been reported between 8 MPa m1/2 and 10 MPa m1/2 for zirconia.³⁰ This is significantly higher than any previous dental ceramic. Fracture toughness is a measure of a material's ability to resist crack growth. Zirconia has the apparent physical properties to be used for multiple-unit anterior and posterior FPDs. Clinical reports on zirconia have not demonstrated a problem with the zirconia framework.^32,34 The problems have been associated with chipping and cracking of porcelain. Using a slow-cooling protocol at the glaze bake to equalize the heat dissipation from zirconia and porcelain increased the fracture resistance of the porcelain by 20%. Zirconia may be in the form of porous or dense blocks that are milled to create the frameworks or recently, full-contour single-unit restorations. Most are fabricated from a porous block, milled oversized by about 25%, and sintered to full density in a 4- to 6-hour cycle. An alternate approach involves milling a fully dense block. However, due to the nature of zirconia, this approach requires approximately 2 hours of milling time per unit whereas milling of the porous block necessitates only 30 to 45 minutes for a three-unit bridge.
Within Classifications 2 and 3, compositions can vary greatly. Several commercial materials are in these groups. Glass-based systems (Category 1 and Category 2) are etchable and thus easily bondable. Crystalline-based systems (Category 3 and Category 4) are not etchable and much more difficult to bond. Categories 1 to 3 can exist in a powdered form that is then fabricated using a wet-brush technique, or they can also be preprocessed into a block that can be pressed or machined. As a general rule, powder/liquid systems have much lower strength than pre-manufactured blocks due to a much larger amount of bubbles and flaws in the finished restoration.

Classification Based on Processing Technique

A more user-friendly and a simplistic way to classify the ceramics used in dentistry is by how they are processed. All materials can be processed by varied techniques; however, in general for dentistry, they can be classified as: 1) powder/liquid glass-based systems; 2) machinable or pressable blocks of glass-based systems; and 3) CAD/CAM or slurry die-processed mostly crystalline (alumina or zirconia) systems. It is an important classification method, as there appears to be a greater correlation to clinical success (and thus failure) due to processing techniques. Even though a material may have the same chemistry and microstructure, the processing methodology used to produce a restoration may improve or decrease the final properties and clinical success. Specifically, machined blocks of materials have performed better than powder/liquid versions of the same material.

1. Powder/Liquid

1A. Conventional

These are typically veneer materials, which may be all glass or a mixture of glass and crystal components. These include veneers for all-ceramic and metal frameworks and may also be used alone as anterior veneer restorations. Typically, these materials are hand-mixed with de-ionized water or a special modeling liquid supplied by the manufacturer. They are built up by hand and vibrated (condensed) to remove water and air. These are fired in a vacuum to help remove remaining air and improve the density and esthetics of the veneer. Because these restorations are handmade, voids are often present in the fired material. This is inherent to the process and may be worse or better depending on environmental conditions, the technician's skill, and the firing cycle. Frequently, one sees bubbles remaining in the hand-layered veneer material.

1B. Slip Casting

The original In-Ceram and some partially stabilized zirconia blocks are fabricated based on slip casting of alumina or zirconia. The "slip" is a homogenous dispersion of ceramic powder in water. The water pH is often adjusted to create a charge on the ceramic particles, and the ceramic powder is coated with a polymer to cause the particles to be evenly suspended in the water. In the case of In-Ceram, the slip is "painted" on a gypsum die with a brush to form the underlying core for the ceramic tooth. The water is removed via capillary action of the porous gypsum, which packs the particles into a rigid network (fig 22). The alumina core is then slightly sintered (0.2% shrinkage) in a furnace to create an interconnected porous network. The lanthanum glass powder is placed on the core; the glass becomes molten and flows into the pores by capillary action to produce the interpenetrating network. The last step in the fabrication involves application of aluminous porcelain on the core to produce the final form of the restoration. Other powder dispersions, such as those created with zirconia, may be poured into a gypsum mold that withdraws the water and leads to a homogeneous block of zirconia being formed.

22 2. Pressable

Pressed ceramic restorations are fabricated using a method similar to injection molding. Monochromatic porcelain or glass-ceramic ingots are heated to allow the material to flow under pressure into a mold formed using a conventional lost-wax technique. The restoration may be cast to its final contours and subsequently stained and glazed to provide an esthetic match. Alternatively, a coping may be molded on which porcelain is added to achieve the restoration's final shape and shade. Empress restorations and other materials with a similar leucite/glass structure are fabricated in this manner. The glass-ceramic IPS e.max is also created this way. Pressables may be used for inlays, onlays, veneers, and single-unit crowns.

3. CAD/CAM

3A. Subtractive

Full-contour Full-contour restorations such as inlays, onlays, crowns, and veneers may be fabricated from various blocks of materials. In general, these blocks are fabricated from starting powders that are mixed with a binder and then pressed into a mold or extruded like a sausage into a block form. The binder helps hold the powder together so that the shape is maintained after pressing or extrusion. Then, the blocks are transferred to a furnace to remove the binder and sinter to full density. As mentioned previously, restorations milled from blocks tend to have improved density and mechanical properties as compared with powder/liquid or pressed restorations due to the standardized manufacturing process (fig23).^35,36
23

Glass/Crystal Vitablocs are fabricated using fine-grain powders, producing a nearly pore-free ceramic with fine crystals. This was the first material specifically produced for the CEREC system and has an excellent history of clinical success for inlays, onlays, and anterior and posterior crowns.36 Sirona CERECblocs are fabricated from the same powders. The restoration may be characterized with external stains, or porcelain may also be added to produce a layered effect (fig 24-25). These blocks are available as monochromatic, polychromatic with stacked shades as in a layer cake, and in a form replicating the hand-fabricated crowns whereas an enamel porcelain is layered on top of dentin porcelain.
fig 24
fig 25

Glass/Leucite Empress CAD is based on the pressable Empress and has the same microstructure—a feldspathic glass with approximately 45% leucite crystal component. These blocks also have a fine leucite crystal structure (approximately 5 µm to 10 µm) and may also be further characterized using external stains or porcelain. Empress CAD is available in monochromatic and polychromatic stacked shades. Strength properties are similar to Vitablocs. A common theme to all of these blocks is a fine particle-size microstructure that helps resist machining damage, improve mechanical properties, and decrease polishing time of the finished restoration.

Lithium Disilicate The IPS e.max^® block (lithium disilicate) is not initially fully crystallized, which improves milling time and decreases chipping risk from milling. The milled restoration is then heat-treated for 20 to 30 minutes to crystallize the glass and produce the final shade and mechanical properties of the restoration. This crystallization changes the restoration from blue to a tooth shade. The microstructural and chemical composition is essentially the same as IPS e.max^® Press. The e.max block has several translucencies, the least translucent being used primarily as a framework material and the higher translucency blocks used for full-contour restorations.
Framework Alumina: Interpenetrating Phase/Glass-Infused In-Ceram blocks are fabricated by pressing the alumina-based powder into a block shape similar to Vitablocs. However, these blocks are only fired to approximately 75% density. Porous blocks of In-Ceram materials are milled to produce a framework. The blocks are then infused with a glass in different shades to produce a 100% dense material, which is then veneered with porcelain. Glass infusion only requires 20 minutes for a coping and 1.5 hours for a three-unit bridge. The microstructure is the same as the slip cast alumina. The blocks are available in all three types of In-Ceram.
Alumina: Porous Alumina frameworks may be fabricated from porous blocks of material. Pressing the alumina powder with a binder into molds produces the blocks. The blocks may be partially sintered to improve resistance to machining damage or used as pressed in a fully "green" state (unfired, with binder). The frameworks are milled from the blocks and then sintered to full density at approximately 1500°C for 4 to 6 hours. The alumina has a fine particle size of about 1µm and strength of approximately 600 MPa and is designed for anterior and posterior single units, as well as anterior three-unit bridges.
Partially Stabilized Zirconia: Porous Zirconia frameworks milled from porous blocks are fabricated similarly to alumina blocks. There are various methods to press the powder into a mold. Uni-axial involves pressing from one direction, biaxial means pressing from two equal and opposite directions, and isostatic essentially indicates uniform pressing in all directions. All methods have advantages and disadvantages; however, the desired result is the same, that is, to produce a homogeneous block that shrinks uniformly. As is the case with the alumina block, the milled zirconia framework shrinks about 25% after a 4- to 6-hour cycle at approximately 1300°C to 1500°C. The particle size is about 0.1 µm to 0.5 µm.
Partially Stabilized Zirconia: "HIP" blocks Fully dense zirconia is produced by hot isostatic pressing. The zirconia powder may be prepressed in a block, or the powder itself is packed into a flexible mold. Either the blocks or mold is then vacuum-sealed in an airtight rubber or plastic bag and placed into a fluid-filled chamber. Pressure is then applied to the fluid and transmitted evenly around the zirconia. Heat is applied to the chamber, which sinters the zirconia to full density (fig 26). Zirconia blocks produced in this manner may achieve flexural strength values of approximately 1200 MPa to 1400 MPa. However, it requires extended milling to produce the framework, and the higher strength value does not generally justify the lost productivity. The accuracy may be improved versus the porous block method and may be preferred for large frameworks that span the arch.

fig 26

3B. Additive

Electrodeposition In-Ceram powder dispersions used in the slip casting technique have been applied to electrodeposition systems, which apply a current across the dispersion and deposit the powder particles automatically on the surface of a conductive die. This approach is efficient for single units but becomes cumbersome and potentially unreliable for multiple-unit frameworks.

Discussion and Summary

Ceramics can be classified in many ways. Two classification systems were given to aid the reader in understanding the types of ceramics available for dental use. Processing technique has a large impact on strength and thus clinical performance and should be one of the primary considerations in choosing a material. There are many clinical aspects that are important for success with all-ceramic materials but are not as critical with metal-based restorations and not possible to cover here (eg, preparation design, management of stresses, cementation techniques). A basic clinical usage guide is shown in table 1. The reader is advised that significant knowledge and training in these areas are requisites for success with all-ceramic materials.
table 1

References

1. Kingery WD, Bowen HK, Uhlmann DR. Introduction to Ceramics. 2nd ed. New York, NY: John Wiley and Sons;1976:1-19.
2. Otto T. CEREC restorations. CEREC inlays and onlays: the clinical results and experiences after 6 years of use in private practice [in French, German]. Schweiz Monatsschr Zahnmed. 1995;105(8):1038-1046.
3. Reiss B, Walther W. Überlebensanalyse und klinische Nachuntersuchungen von zahnfarbenen Einlagefüllungen nach dem CEREC-Verfahren [in German]. Zahnaerztl Welt. 1992;100(5):329-332.
4. Heymann HO, Bayne SC, Sturdevant JR, et al. The clinical performance of CAD-CAM-generated ceramic inlays: a four-year study. J Am Dent Assoc. 1996;127(8):1171-1181.
5. Berg NG, Derand T. A 5-year evaluation of ceramic inlays (CEREC). Swed Dent J. 1997;21(4):121-127.
6. Reiss B, Walther W. Ereignisanalyse und klinische Langzeitergebnisse mit Cerec-Keramikinlays [in German]. Dtsch Zahnarztl Z. 1998;53(1):65-68.
7. Reiss B, Walther W. Clinical long-term results and 10-year Kaplan-Meier analysis of Cerec restorations. Int J Comput Dent. 2000;3(1):9-23.
8. McLaren EA, Giordano RA, Pober R, et al. Material testing and layering techniques of a new two phase all glass veneering porcelain for bonded porcelain and high alumina frameworks. Quintessence Dent Technol.2003;26:69-81.
9. McLaren EA, Giordano RA. Zirconia-based ceramics: material properties, esthetics, and layering techniques of a new veneering porcelain, VM9. Quintessence Dent Technol. 2005;28:99-111.
10. Wagner J, Hiller KA, Schmalz G. Long-term clinical performance and longevity of gold alloy vs ceramic partial crowns. Clin Oral Investig. 2003;7(2):80-85.

Management of Dentoalveolar Ridge Defects for Implant Site Development: An Interdisciplinary Approach

2011-09-26T12:14:00.000+03:00

Management of alveolar ridge defects can present significant biologic and esthetic challenges for optimal implant placement when attempting to achieve a natural implant restoration outcome. The alveolar bone serves two functions for the implant: biologic, by housing the implant for osseointegration; and esthetic, by supporting the overlying peri-implant soft-tissue architecture, ultimately permitting the presentation of soft-tissue contours. Furhauser et al devised a pink esthetic score to evaluate esthetic success around single tooth implants.¹ A careful study of their criteria indicates high esthetic success will be met when the implant is completely housed in bone and the crest is in a defined relationship to the papillary tips and facial-free gingival margin. These relationships have been established and quantified for natural teeth^2-8 and
implants.^9-18 Proper management of ridge defects allows the clinician to achieve a higher pink esthetic score and, hence, more natural gingival contours for implant restorations for esthetics and stability of the peri-implant topography.¹⁹
Dentoalveolar ridge defects can arise from failure of the alveolar bone to form properly or
by destruction of the existing alveolar bone. Failure of the alveolar bone to form has two local causes: congenital tooth absence, which inhibits alveolar bone growth, or ankylosis of a tooth before completion of facial growth,^20-22 which arrests further alveolar bone growth. Destruction of existing alveolar bone has three causes: infection, trauma, or tooth loss. Infection can be from root fracture, endodontic origin, periodontitis, or peri-implantitis.
Defects that are of critical size do not spontaneously regenerate following injury, without adjunctive measures.²³ They are recognized as having innately limited potential for alveolar regeneration and are required to be managed through bone regeneration techniques.²⁴ When large dentoalveolar ridge defects exist, reestablishing a proper dentoalveolar ridge contour for an implant can be challenging, regardless of whether the defect is horizontal, vertical, or a combination.²⁵ Predictable bone regeneration is dependent on four major biologic principles: primary wound closure, blood supply, space maintenance, and wound stability.²⁶ The source of new bone is dependent on adequate blood supply at the site. The blood supply provides the necessary cells, growth factors, and inhibitors to initiate the osteogenic-biomineralization cascade. Osteocytes arise from stromal cells of the bone marrow and precursor cells that travel with capillary walls or circulate in the blood.²⁷ Angiogenesis involves the formation of new capillaries that grow into a defect. The key to bone formation is promoting angiogenesis. The source of these new capillaries is from the remaining walls adjacent to the defect. Bone grafts maintain the volume of space of the defect, initiate bone resorption through inflammation, supply growth factors that are released as the graft is resorbed, and act as a chemo-attractant for angiogenesis. Bone-grafting success is most predictable when healing occurs in a contained environment (ie, primary intention wound healing is ensured) and new capillaries are allowed to fully vascularize the reconstruction.^28-30 In general, horizontal alveolar bone defects are more predictable to treat because more walls (sources) are present for capillary in-growth into the osseous defect that is being reconstructed. Therefore, the capillaries have less distance to migrate for full infiltration of the defect. Vertical defects are less predictable to reconstruct because greater demands are placed on capillary migration and in-growth. The further the distance the capillaries must travel, the more difficult it is to achieve complete vascularization of the defect (Figure 1).

Distraction osteogenesis is a newer modality of guided bone regeneration (GBR) and has been used to help rebuild severe ridge defects.³¹ Orthodontics essentially is a form of distraction osteogenesis. Such therapy has been a long-standing modality of periodontal-orthodontic treatment to reduce or eliminate infrabony defects around teeth.³² Using distraction osteogenesis via tooth movement for GBR allows the clinician greater latitude in determining the size of the osseous defect to correct. Through tooth movement, the clinician can minimize the size and extent of the dentoalveolar ridge defect and have more predictable bone grafting. The smaller the defect, the more predictable the regenerative result will be.
The following case study illustrates the concept of orthodontically directed site development to optimize interdisciplinary implant dentistry.

Case Report
A 28-year-old Caucasian female presented to the periodontist with a complaint of a mobile implant in the site of tooth No. 22 (Figure 2 and 3). The patient had a congenitally missing tooth No. 23. No. 22 had erupted into site No. 23, leaving a vacancy at site No. 22, and was the reason for the original implant at site No. 22.
fig 2

fig 3

The patient had no medical concerns and had a history of an implant placement in December 2002 when she was 25 years old. In February 2005, she presented with a mobile implant and an associated advanced peri-implantitis. Radiographic review at the initial examination demonstrated significant destruction of the dentoalveolar ridge around the implant as well as around the adjacent natural dentition. Emergency-based treatment involved surgical implant removal only and debridement of the infection (Figure4 and 5). Following uneventful healing, an advanced ridge defect was apparent at the edentulous site and moderate and advanced attachment loss noted at No. 22D and No. 21M, respectively (figure 6 and 7). This case demonstrates bone loss of two separate origins: lack of bone because of tooth agenesis and destruction of bone from inflammatory peri-implantitis.
fig 4

fig 5

fig 6

fig7

Because of the apparent bone loss, seen on the radiograph, on the mesial of tooth No. 21 and the distal of tooth No. 22, one suggestion was to remove teeth Nos. 21 and 22 and, subsequently, site-develop the regional anatomy for implant placement. The surface area requiring GBR was expected to be rather large, whereby autogenous bone grafting from the chin would have been elected to augment the site in both the horizontal and vertical dimensions. Following 6 months of healing, implant placement would ensue at either position, Nos. 21 or 23, to be restored as a bridge or at position Nos. 21 through 23 for individual implant restorations.
This approach incurred significant risk and inherent difficulty in meeting the biologic and esthetic goals of the patient. To recreate ideal soft-tissue contours, the graft would have to reach a vertical height that supports the papillary tips at a level as coronal as the papillary tips on the adjacent natural teeth (not to the level of the free gingival margin on the facial of the teeth). A vertical augmentation of this magnitude is the most difficult to achieve and has the least predictability. Autogenous block grafts are highly successful but do possess inherent challenges that include, but are not limited to, ensuring primary closure, minimizing infection during healing, ensuring graft stabilization and intimacy of fit during surgery, and having paresthesia potential from the operation. From an esthetic perspective, three implants placed adjacently pose a challenge for maintaining papillary soft-tissue form between implants.³⁴ Two implants would be less challenging in this regard; however, the requirements for pontic site development would remain and require multiple periodontal plastic surgical procedures. In either option, optimal esthetic, biologic, occlusal, and biomechanical outcomes are at a compromise compared with a healthy natural dentition for the patient from a long-term predictability standpoint.
Another suggestion was to minimize the extent of the defect by moving the teeth orthodontically into the bony defect. First, tooth No. 22 would be returned to its proper functional and anatomic position. This approach would reduce the bony defect from the mesial aspect by the volume of one tooth. To reduce the defect from the distal aspect, tooth No. 21 would be extruded and extracted. To further reduce the defect, tooth No. 22 would be moved distally into site No. 21. Tooth No. 22 then would be force-erupted and extracted. This strategy would confine the bony defect to only the size of one tooth and change the character of the defect from having only one source of capillary in-growth to having three sources. Site No. 21 could be managed with mineralized freeze-dried bone allograft and a membrane. Implant site development requirements theoretically would be reduced, optimizing predictability and reducing surgical morbidity for the patient. Orthodontic tooth movement (eg, orthodontically directed distraction osteogenesis) would serve to rebuild the vertical height of the ridge and eliminate the need for an autogenous block graft. In addition, proper positioning of the cuspid via orthodontic tooth movement would create a more idealized occlusal scheme, provide a cuspid-protected occlusion, and minimize off-axis loading of the implant.
This treatment plan was elected with the premise to reevaluate treatment options during orthodontic tooth movement. Soft-tissue augmentation was initiated to correct the mucogingival defect in the area of teeth Nos. 21 and 22. A free gingival graft was performed to achieve an adequate band of attached and keratinized gingiva to resist potential stripping on the root surfaces of teeth Nos. 22 and 21 during orthodontic movement (figure 8). Orthodontic movement then was initiated to site-develop position No. 23 for an implant (figure9-11). Orthodontics also was used to idealize the patient’s occlusion and develop canine guidance to minimize occlusal load and maximize the redistribution of forces^36-40 for protecting the future implant from deleterious forces. The space was opened around the peg lateral tooth No. 7, and the gingival levels were aligned for maxillary incisors. Bonding was performed to restore the length of teeth Nos. 8 through 10 and to bond the peg lateral to a normal tooth form, which allows the orthodontist to idealize the posterior occlusal scene and maintain canine guidance (figure 12- 13).
fig 8

fig 9

fig 10

fig 11

fig 12

fig 13

Following thefirst goal of orthodontia—moving tooth No. 22 to a proper functional and anatomical position—a periodontal reevaluation was performed, demonstrating an improvement in short- and long-term tooth prognosis. At this time, the decision was made to abort continual extrusion of teeth Nos. 21 and 22, although some attachment level discrepancy remained between Nos. 21 and 22 (figure 14). Implant diagnostics ensued and included mounted study models and a diagnostic wax-up. A scanning appliance was created to demonstrate the desired prosthetic outcome requirements, and the patient was referred for computed tomography (CT) scans. CT scan assessment demonstrated successful orthodontically directed GBR to allow implant placement (figure 15-16). Only minor GBR therapy would be needed and could be accomplished simultaneously with implant installation. Guided implant placement occurred, using an open flap approach (figure 17). During surgery, root dehiscences were noted on teeth Nos. 21, 22, 24, and 25, as well as the anticipated dehiscence following implant placement at No. 23 (fig 18). A positioning reference (index) was secured after implant placement to facilitate a provisional prosthesis at stage II surgery. Cortical perforations then were placed adjacent to the implant to encourage angiogenesis (figure 18), and mineralized freeze-dried bone allograft enhanced with platelet-derived growth factor was placed over the dehiscences for purposes of guided tissue regeneration and GPR (figure 19). A highly resorbable collagen membrane was placed to stabilize the allograft. The flap was coronally repositioned, and primary-intention wound healing was achieved (figure 20-21). Following 4 months of stage I surgery, implant uncovery and immediate provisionalization was performed in conjunction with connective tissue grafting. Final orthodontic tooth movement then ensued, using the implant as anchorage to optimize end-tooth movements, interroot separation, and the cuspid-protected occlusal scheme. A final impression then was secured, and a zirconia abutment (fig 22) with an all-ceramic restoration was fabricated for the prosthetic phase completion of No. 23 (fig 23-25).
fig14
fig15
fig16

fig 17-18

fig19

fig 20
fig 21
fig 22
fig 23
fig 24
fig 25
This case illustrates how to manage dentoalveolar ridge destruction, using orthodontics, periodontics, and restorative dentistry to idealize the occlusal scheme, develop an ideal implant site with orthodontics, and enhance the dentoalveolar ridge dimensions surgically with bone graft materials. Finally, it demonstrates how to restore proper tooth contours through minimal restorative dentistry with bonding and a single-unit, implant-supported crown.

References

1. Fürhauser R, Florescu D, Benesch T, et al. Evaluation of soft tissue around single-tooth implant crowns: the pink esthetic score. Clin Oral Impl Res. 2005;16(6):639-644.
2. Gargiulo A, Wentz F, Orban B. Dimensions and relations of the dentogingval junction in humans. J Periodontol. 1961;32:261.
3. Sanavi F, Weisgold AS, Rose LF. Biologic width and its relation to periodontal biotypes. J Esthet Dent. 1998;10(3):157-163.
4. Becker W, Ochsenbein C, Tibbetts L, et al. Alveolar bone anatomic profiles as measured from dry skulls. Clinical ramifications. J Clin Periodontol. 1997;24(10):727-731.
5. Spear FM. Maintenance of the interdental papilla following anterior tooth removal. Pract Periodontics Aesthet Den. 1999;11(1):21-28.
6. Tarnow DP, Magner AW, Fletcher P. The effect of the distance from the contact point to the crest of bone on the presence or absence of the interproximal dental papilla. J Periodontol. 1992;63(12):995-996.
7. Kois JC. Altering gingival levels: the restorative connection part I: biologic variables. J Esthet Dent. 1994;6(1):3-7.
8. Vacek JS, Gher ME, Assad DA. The dimensions of the human dentogingival junction. Int J Periodontics Restorative Dent. 1994;14(2):154-165.
9. Berglundh T, Lindhe J. Dimension of the periimplant mucosa. Biologic width revisited. J Clin Periodontol. 1996;23(10):971-973.
10. Abrahamsson I, Berglundh T, Wennström J, et al. The peri-implant hard and soft tissues at different implant systems. A comparative study in the dog. Clin Oral Implants Res. 1996;7(3):212-219.
11. Hermann JS, Cochran DL, Nummikoski PV, et al. Crestal bone changes around titanium implants. A radiographic evaluation of unloaded nonsubmerged and submerged implants in the canine mandible. J Periodontol. 1997;68(11):1117-1130.
12. Cochran DL, Hermann JS, Schenk RK, et al. Biologic width around titanium implants. A histometric analysis of the implant-gingival junction around loaded and unloaded nonsubmerged implants in the canine mandible. J Periodontol. 1997;68(2):186-197.
13. Small PN, Tarnow DP. Gingival recession around implants: a 1-year longitudinal prospective study. Int J Oral Maxillofac Implants. 2000;15(4):527-532.
14. Hermann JS, Buser D, Schenk RK, et al. Crestal bone changes around titanium implants. A histometric evaluation of unloaded non-submerged and submerged implants in the canine mandible. J Periodontol. 2000;71(9):1412-1424.

Managing Curved Canals: the Straight-Away and Super Glide Path Technique

2011-09-26T06:43:00.000+03:00

Unfortunately, not all root canals are straight. Clinicians regularly encounter curves of different degrees and in various places all along the root canal system. These curves cause a host of problems, including ledge formation, perforation, apical transportation, zip formation, and file separation (Figure 1) This article is intended to aid the clinician in identifying the degree, type, location, and direction of the various root canal curves and will provide suggestions for their management and instrumentation. The technique advocated by the author and presented in this article entails understanding how to use and
exploit rotaries, and will even benefit the practitioner who only undertakes the management of straight canals. A system offering a .02 tapered file (such as K3, Quality Endodontic Distributors, Peterborough, England; RaCe, FKG Dentaire SA, La Chaux-de-Fonds, Switzerland; or Quantec™, SybronEndo, Orange, CA) is integral to the technique.
figure 1
The discussion assumes that throughout the root canal procedure, proper irrigation, lubrication, and recapitulation occurs and that there is no violation of the apical termination, and therefore those aspects will not be discussed in detail.

CLINICAL TECHNIQUE Apical Curves

The first step is to gain access to the pulp, and then, using a tapered diamond, flare the walls of the pulp chamber to such an extent that all of the canal orifices in the chamber will be visible with one eye closed, as if looking into a camera lens.² This is called “straight-line access” (Figure 2). Straight-line access eliminates the irregular walls in the pulp chamber, allowing the file to negotiate the canal with less stress. When straight-line access is achieved, the file will not have to bend to get into the root canal orifice.
figure 2
After gaining straight-line access, a No. 8 or a No. 10 reamer—not a K file—should be used to go to working length. This step will serve four purposes: to check the patency; to determine the working length; to achieve the initial glide path; and to make an impression of the canal. The advantage of using a reamer over a K file is that the reamer’s “dead soft” quality yields a perfect impression of the curves in the canal when it is removed (Figure 3).Before removing the reamer, however, use a magic marker to mark the labial or buccal surface handle of the instrument to serve as a reference point. The reamer’s impression mirrors the degree, type, location, and direction of the curve. Because the reamer is more flexible than the K file, there is also less chance of apical transportation or zipping. Avoid using either a stainless-steel hand file or a stainless-steel reamer above No. 10 in a curved canal because they are too inflexible.
figure 3
If the impression shows that the curved canal is at the apical third, as shown in Figure 4, measure the reamer up to the curve. Use this straight-away length to instrument with orifice openers, such as the K3 shapers, in a crown-down fashion, up to the curve but not beyond. Where the shapers cannot reach the total straight-away length, continue instrumenting with .04 rotary nickel titanium (Ni-Ti) instruments in a crown-down fashion until the total straight-away length is negotiated (ie, up to the curve). At this point, going beyond the curve with inflexible orifice openers and .04 rotary Ni-Ti instruments may perforate or ledge the canal. Making this “straight-away” will remove all of the restrictive dentin in the coronal and middle two thirds of the canal, which will facilitate subsequent files in reaching working length.
figure 4
After achieving patency, making an impression, creating an initial glide path, and crafting the straight-away, the next step is to create a well-defined glide path, or what the author calls a “super” glide path. This will make it easier to negotiate the canal and curve with subsequent instruments. To create a super glide path, .02 tapered rotary Ni-Ti instruments should be used in a crown-up fashion; that is, first use a .02 No. 15 to working length; then use a .02 No. 20 to working length; and, if possible, finish with a .02 No. 25 to working length. Because a straight-away was created, there should be no problem negotiating the curve to working length using .02 tapered rotary Ni-Ti files. These highly flexible .02 rotaries will glide right through the canal and past the curve.
Now that this super glide path has been created with the .02 tapers, the .04 tapered Ni-Ti rotary instruments can be used in a crown-down fashion beyond the curve to working length; ie, use a .04 No. 35 followed by a .04 No. 30, and so on, finishing with a .04 No. 15. Recapitulate until the master apical file reaches working length, which in a severely curved canal should be a No. 20 or No.25. If the .04 tapers will not advance easily, use .02 tapers in a crown-down fashion and then return to the .04 tapers. Avoid using .06 rotary Ni-Ti tapers in a canal with a sharp curve as these wider tapers have less flexibility, increasing the chance of file separation.

Banana Curves

By contrast, if the impression shows a mid-root banana curve, obtain the straight-away length by measuring up to the level of curvature (Figure 5).⁴ Again, use the impression of the canal for these calculations. Because mid-root banana curves tend to be more gradual and less acute than apical curves, they allow for straight-away measurement all the way to the level of curvature. This is unlike the straight-away in the acute apical curve, which stops at the very beginning of the curve. The short straight-away distance in the mid-root banana curve requires only shapers to negotiate the straight-away length, unlike the apical curve, whose length may require both shapers and rotary Ni-Ti instruments. Because the straight-away length in mid-root banana curves is mostly located in the coronal third of the root, which is wide, it is thus able to accommodate shapers. Do not attempt to go around the bend with shaper instruments or any orifice openers because this may create a ledge or perforation. The straight-away in this case transforms a C-shaped canal into a J-shaped canal (Figure 6).⁵ Always direct the shapers away from the furca so as not to strip or perforate the thin wall in that location. After making a straight-away, create a super glide path by following the steps described above, then crown-down with .04 rotary Ni-Ti instruments, which will now easily glide past the mid-root curve.
figure 5
figure 6

S-Shaped Curves

Now the attention shifts to the challenging S-shaped curve, usually found in upper premolars (Figure 7). Because S-shaped curves consist of two curves, they usually present a greater risk of file separation than the apical and mid-root banana curves, as the file must pass through both curves.³ Make a straight-away up to the beginning of the first curve. This length is usually short enough for the shapers or any orifice openers alone to make the straight-away. Look at the impression to calculate the measurement, then create a super glide path to working length by using .02 rotary Ni-Ti instruments in a crown-up fashion as described above (.02 No. 15; .02 No. 20; and .02 No. 25). Then use these same .02 tapers, this time in a crown-down fashion, from .02 No. 35 to .02 No. 15. Recapitulate until at least the master apical file reaches to working length, then start to crown-down with .04 rotary Ni-Ti instruments. This technique, though requiring a greater number of files than the apical or mid-root banana curves, is safer because it helps prevent file separation. It would be unwise to crown-down initially with .04 rotary Ni-Ti instruments because the S-shaped curve requires negotiating two curves.

figure 7

Merged Canals

Where a root has two canals that merge into one near the apex, attack one of the curves head on and outflank the other. This type of curve is usually found in the mesial roots of lower first and second molars (Figure 8). Here again, achieve patency, make an initial glide path, and make an impression all in one step by using a No. 8 or a No. 10 reamer to working length in the straighter of the two canals. Then create a straight-away, make a super glide path, and crown-down to working length in the straighter of the two canals only. In the second canal, crown-down only to the merger point; do not attempt to deflect the file around the turn because it may bind and separate.⁶
^{Figure 8}

DISCUSSION

Many clinicians instrument the curve in the canal exclusively by hand and only use rotaries for the straight part of the canal. There are also some clinicians who use hand instruments greater than a No. 10 to make a glide path. Neither of these approaches is advisable because hand instruments greater than No. 10 in the canal may cause an iatrogenic event. Even if a No. 15 hand file passes through a severely curved canal initially, very often it will not be able to negotiate the curve a second time. The only hand instrument that should be used in a severely curved canal is a No. 8 or a No. 10 reamer, which will follow the curve without any need to pre-bend. The author has found through experimenting on extracted teeth with curved canals that hand instruments above No. 10 can easily create a ledge or transport or zip the apex. Often, a zip or transportation may not even be apparent on a radiograph. The clinician will believe that he or she performed the perfect root canal on a curved root, when in reality the canal was transported or zipped.
When preparing a straight canal, any system will work. But when it comes to a severely curved canal, the curve has to be well-prepared before using any of the systems to prevent an iatrogenic event. Just like a tooth with a severe curve must be loosened with either proximators, luxators, elevators, or periotomes before the extraction forceps are employed so that the root does not fracture during the extraction process, so too a well-defined glide path must be made to prepare the curved canal for instrumentation and shaping.

ACKNOWLEDGMENTS

The author would like to acknowledge Michael Reiss, Yitzchok Segal, and Dr. Shahab Cohen for their assistance in the preparation of this article.
REFERENCES
1. Ingle JI. Root canal preparation. In: PDQ Endodontics. BC Decker, Hamilton, Ontario: 2005;129.
2. Brave D, Koch K. Locating the elusive root canal. DentalTown. 2007;8(1):53.
3. Curtis ML. 100’s of Pearls on Endodontics. Chapter 5: Tips and Tricks for Common Endo. Hundreds of Pearls, LLC; Michael L. Curtis, Publisher. 2005;93-95.
4. Mounce R. Negotiating challenging mid root curvatures: rounding the bend. Dentistry Today.2007;26(2):108.
5. Deutsch AS, Musikant BL. Innovations in endodontics: the same ends by simpler means.Endo Tribune U.S. Edition.
6. Weathers A. File breakage in endo. LVI Visions. 2005;Sept/Oct/Nov:44.

RESTORING ENDODONTICALLY TREATED TEETH

2011-09-26T00:15:00.001+03:00

Consider the following scenario: A patient sits in the treatment room, ready to have a filling replaced due to marginal breakdown and secondary decay. The practitioner clearly warns the patient that trauma to the tooth can cause the nerve to become irritated and symptomatic, which results in the need for endodontic therapy.
Furthermore, determining the extent of the decay is difficult until caries excavation begins. Therefore, it is too soon to predict whether endodontic therapy will be necessary. What the doctor has failed to mention is that the cost and time investment of the final restorative procedure will drastically differ from a filling replacement if a root canal is indeed indicated. The patient requests that the dentist stop drilling before the nerve is approached, so as to avoid a root canal. The patient is assured that the dentist will go slowly, in order to prevent performing a root canal if possible. Predicting the extent of the decay, however, is impossible without further caries removal.

Sure enough, the decay is extensive, and a pulpal exposure occurs during caries removal. The patient is notified that the nerve has been exposed, and root canal therapy is ultimately indicated. At this point, the patient is made aware that a post, core, and crown will be required after the root canal. The patient asks why several procedures are now needed when a filling was sufficient before, and wonders if a filling could just be placed after the root canal is completed.
It may be a common misconception in dentistry that a root canal goes hand-in-hand with a post and crown, but the questions concerning whether these additional procedures are really necessary are valid ones. It may be possible to restore the tooth with a direct restorative procedure, but will this elicit the best long-term outcome? How much tooth structure will remain once caries removal is completed? Can the endodontic access be closed with a direct composite? Is there enough tooth structure remaining to establish ferrule? When and why is a post-and-core build-up required?
As historically described in the literature, full-coverage crowns should only be used when there is insufficient coronal tooth structure for a more conservative restoration, or if functional or parafunctional stresses require the splinting effect of full coronal coverage.¹ This may indicate that full coverage should possibly be avoided unless the above criteria are present.
Still, more questions remain: Does a more “conservative restoration” have the best long-term predictability? Is it still considered a conservative procedure if failure of the endodontically treated tooth is the ultimate outcome? One study explored whether coronal coverage impacted the survival rate of endodontically treated teeth. Tooth loss was six times higher in endodontically treated teeth without coronal coverage.² Another clinical trial demonstrated an average time of 87 months before extracting an endodontically treated tooth, compared to 50 months without full coverage.³ In light of this information, the clinician must again consider which procedure is more conservative.
Before determining the least aggressive, most predictable restoration, it is important to first understand how the tooth structurally changes upon completion of endodontic therapy. Over time, views on changes in mechanical properties of endodontically treated teeth have varied. In 1983, Carter noted that endodontically treated teeth exhibit a fragility that vital teeth do not. He made reference to the low-moisture content of root canal teeth, and demonstrated that vital teeth had higher punch shear strength and toughness values.⁴ This idea was countered nearly a decade later, through a study that tested biomechanical properties such as punch shear strength, toughness, load to fracture, and microhardness of dentin in endodontically treated teeth as compared to vital teeth. The study concluded that teeth do not become more brittle after endodontic treatment.⁵ More importantly, the study determined that it is not the change in biomechanical properties of dentin in endodontically treated teeth that contribute to challenges in restorability of the tooth. Rather, the amount of remaining tooth structure, specifically dentin, illustrates a direct relationship with resistance to occlusal forces
Given this knowledge, the clear goal in restoring an endodontically treated tooth is to preserve as much dentin as possible. If the restorative dentist is not completing the endodontic therapy, then communication between the restorative dentist and endodontist is vital to ensure the maximum amount of dentin remains (Figure1 and 2). In order to evaluate restorability of the tooth, the restorative dentist must be sure to remove all decay before recommending endodontic therapy. The endodontist can better evaluate the predictability of the endodontic therapy if the restorative plan can be communicated before beginning root canal therapy. The endodontist can also modify treatment, if necessary, to leave a post space that removes the least amount of dentin and best follows the anatomy of the canal, with which they are already familiar.⁷ Achieving endodontic success requires properly cleaning and sealing the canal as well as setting the proper restorative path for the tooth, taking into consideration the rest of the dentition in the patient’s mouth in order to obtain the best long-term outcome. Occlusion, position in the arch, and periodontal health must also be considered.⁸ When discussing the long-term success of an endodontically treated tooth, it might seem logical to think that the majority of root canals that fail are due to endodontic origin. However, one clinical study that classified failures of endodontically treated teeth found restorative origin to be the primary reason for failure. Conversely, the least amount of failures resulted from endodontic causes.

FIGURE 1 FIGURE 2

This surprising finding reveals the important role the restorative dentist plays in the long-term success of root canal therapy. The restorative dentist must consider whether the treated tooth is only one in a mostly stable and healthy dentition with all remaining teeth providing proper masticatory function, or if several teeth are missing. There are other variables to account for as well, including periodontal disease, malpositioning of the tooth, mobility, malocclusion, and parafunctional habits. If the tooth is subjected to carry supplemental occlusal forces, it may be at greater risk for failure of the restoration as well as possible vertical root fracture in an otherwise properly endodontically treated tooth (FIGURE 3).

If the goal of the endodontist is to sterilize and seal the canal, then the restorative dentist’s goal is to maintain that coronal seal with a stable restoration. Several factors must be weighed when choosing a composite restoration as the material of choice in restoring an endodontically treated tooth. As previously noted, preservation of dentin is very important in the restoration of an endodontically treated tooth. So, the preservation of tooth structure is an obvious benefit of restoring with a direct restoration.
Adhesive dentistry was initially discussed by Buonocore in 1955, when he found that acid-treating enamel increased adhesion of acrylic-based filling materials.⁹ Acid-etching causes microporosities in enamel, in which resin can flow to achieve micromechanical retention. When restoring an endodontically treated tooth with significant removal of tooth structure, enamel may not be readily available to achieve a predictable bond, which is why dentinal bonding becomes increasingly important. Bonding to dentin can be more challenging, due to the natural moisture content of dentin and the hydrophobic qualities that most dentin-bonding agents possess. Nakabayashi et al first described the infiltration of monomers having both hydrophobic and hydrophilic groups as a successful adhesive technique.¹⁰
Although new methods of dentinal bonding are continually being researched, there are still limitations to the technique. These limitations include polymerization shrinkage that can lead to fractures in the tooth or result in gap formations at the weakest points of the dentin bond, and loss of bond strength that leads to eventual leakage.¹¹ Additional drawbacks to bonding in a root canal system, such as C-factor and irrigants used during the endodontic procedure, should be considered. C-factor is defined as the ratio of bonded surfaces in a cavity to unbounded surfaces. As the number of bonded surfaces increase, so does the risk of debonding from the dentin as a result of the stresses from polymerization shrinkage. Essentially, every dentinal wall in a root canal system has an opposing wall, which results in an extremely unfavorable C-factor.
The irrigant used during the root canal treatment can also have potential negative effects on the bond. Sodium hypochlorite, a common irrigant, is also an oxidizing agent, and thus can leave behind an oxygen-rich layer that can inhibit polymerization of resins. This leads to decreased bond strength and an increased risk of microleakage. It has been shown that application of materials such as Accel (Sun Medical Co, www.sunmedical.co.jp) and rosmarinic acid could neutralize the oxidizing effect, therefore increasing the bond strengths to dentin treated with sodium hypochlorite.¹³ Perhaps most importantly, increased cuspal deflection in molars has been shown to occur as a result of increased removal of tooth structure, particularly after endodontic access. This reinforces the importance of full cuspal coverage in an endodontically treated tooth.¹⁴
While full cuspal coverage has been shown to significantly increase the success rate of a posterior endodontically treated tooth, there is no considerable improvement in the success of an anterior endodontically treated tooth. Furthermore, intracoronal reinforcement does not necessarily provide an increased resistance to fracture or dislodgement.¹⁵ Forberger and Gohring demonstrated the opposite, by evaluating marginal continuity and fracture resistance of all-ceramic crowns with differing substructures.¹⁶ It was shown that endodontically treated premolars restored with post-and-core foundations had significantly greater resistance to stress and loading forces, as compared to crowns without the placement of access cavity restorations. Additionally, teeth restored with a rigid post-and-core substructure demonstrated less marginal leakage than teeth with a non-rigid post and core.¹⁶ The benefits of full cuspal coverage in an endodontically treated tooth have become more apparent. The argument for a post and core, however, becomes much more involved due to the conflicting data on their risks and benefits, especially with the wide variety of features different post systems offer.
Added retention to a tooth with minimal remaining tooth structure is the primary reason for placement of a post. The benefit of added retention, however, must be weighed against the potential risks of post-space preparation. These risks include the possibility of disturbing the root canal seal, the excessive removal of dentin—thereby weakening the tooth—and risk of root perforation. Rigid post and cores such as cast gold, zirconia, or ceramic have been shown to be the least desirable post design for stress transmission.¹⁷ Rigid posts are very stiff, which gives them added strength under loads, but can also lead to increased root fracture, due to transmission of forces to less rigid dentin. Ceramic and zirconia do not possess the darkness that metal does, and may provide a more esthetic option for a rigid post. But, using a noble metal to cast a post and core means that less tooth structure needs to be removed. Compared to a stiffer material, fewer forces are ultimately transmitted to the tooth.
Obtaining a passive fit as well as venting the restoration before cementation is very important in avoiding unnecessary pressure in the root canal system. In order to obtain a path of insertion, a cast post also requires increased removal of tooth structure. More tooth structure can be preserved, however, in a pre-fabricated post. Non-rigid posts, such as pre-fabricated fiber posts, have become the treatment of choice in most circumstances when posts are indicated. Although non-rigid posts reduce the transmission of forces to the tooth—which can lead to increased marginal leakage over time—the benefits of these reduced forces outweigh the possibility of marginal leakage. The decreased load transferred to the root dentin leads to less irreparable root fractures upon failure (FIGURE 4).¹¹ This is significant because marginal leakage has the potential for repair, whereas a root fracture almost always does not.

Regardless of post placement, it has been shown that the design of the ferrule is essential in improving load resistance in root-canal treated teeth, despite varying degrees of post length.¹⁸Guidelines for a proper crown preparation include well-defined margins with appropriate axial and occlusal reduction, and proper margin selection based on the type of crown being fabricated, axial wall height of at least 3 mm, and nearly parallel opposing walls, minimally tapered (FIGURE 5).

If a tooth is badly broken down, these criteria become more difficult to achieve, and other criteria such as ferrule design become increasingly important. In dentistry, ferrule is defined as a metal band or ring that encircles the tooth in order to provide retention and resistance form, as well as protect the tooth from fracture. Generally, at least 2 mm of ferrule is desired, but one study showed that at least 1 mm of coronal tooth structure improved fracture resistance. Still, 2 mm is strongly recommended. The same study showed that parallel walls proved to be the most critical factor in resistance to dislodgement, more so than margin design and axial width of the tooth at the crown margin.¹⁹ If ferrule cannot be obtained, other procedures such as clinical crown lengthening, orthodontic extrusion, or possible extraction may become necessary.
What are the benefits of pursuing such treatment, given the increasing number of dental implants being placed, and such ambiguity regarding the best, most predictable method of restoring an endodontically treated tooth? Successful endodontic and restorative treatment provides patients with the opportunity to preserve their natural dentition with excellent function for several years. Furthermore, the preservation of the tooth and periodontal ligament will enable the patient to maintain proprioception, which would otherwise be lost.
There may be some controversy surrounding the best method of restoring an endodontically treated tooth. But, once it is determined that a post, core, and crown are the appropriate treatment, placing the best possible restoration gives the patient a significantly better chance of increasing the life of the endodontically treated tooth. Determining which restoration is most conservative is left up to individual practitioners, and should be determined on a case-by-case basis. What is most important is having the appropriate knowledge to be able to make that decision confidently.

Case Report 1

The patient presented with an existing occlusal amalgam on tooth No. 18. The patient reported temperature sensitivity and percussion sensitivity, and was referred to a specialist where the root canal was completed. The patient returned for final restoration at the completion of root canal therapy where a pre-fabricated post was fit and bonded in place (FIGURE 6). After the post, a composite build-up was used to replace the missing tooth structure that was removed during the endodontic therapy (FIGURE 7). The need for a full-coverage crown was discussed with the patient prior to having the root canal completed (FIGURE 8). Communicating with the endodontist to outline the final restorative plan for the tooth was extremely important. In this case, the endodontist was able to prepare an appropriate post space before the patient returned to the restorative dentist. This not only saved the restorative dentist time during the restorative procedure, but it also ensured that excess dentin removal did not occur (FIGURE 9 and 10). Conversely, if the endodontist creates a post space unnecessarily, undue forces may be placed on the root.
FIGURE 6
FIGURE 7
FIGURE 8
FIGURE 9
FIGURE 10

Case Report 2

This patient presented with a fractured tooth No. 9. Endodontic therapy was completed and the tooth was prepared for a full-porcelain crown (FIGURE 11 and 12). For several reasons, the decision to fabricate a casting was made. While there are different ways of fabricating a cast post and core, inlay resin was used for this patient (FIGURE 13). The casting was fabricated using high noble alloy (FIGURE 14). One of the reasons that the decision to use a casting was made was due to the size of the build-up in relation to the size of the post. If a prefabricated post and core was used, the retention of the build-up would rely solely on the bonding because of the ratio of the build-up to the post. This concept is similar to looking at the crown-to-root ratio when considering different restorative plans. Furthermore, attention also had to be paid to the deep bite that this patient possessed (FIGURE 15). If excessive loads were placed on this anterior tooth, these loads would be transferred to the underlying post and core. In this case, because of the size of the tooth, location of the tooth and forces placed on this tooth, it made more sense to fabricate a cast post and core.
FIGURE 11
FIGURE 12
FIGURE 13

FIGURE 14
FIGURE 15

ORAL DIAGNOSIS IN GENERAL DENTAL PRACTICE

2011-09-25T23:06:00.003+03:00

One of the primary goals for healthcare providers is to prevent disease and to arrest and even reverse the progression of any condition that is already present. A dental clinician’s most important function is the thorough assessment and evaluation of the patient’s oral and associated systemic health. An examination should not focus just on the dentition and the immediately surrounding periodontal tissue—the other structures and conditions of the oral cavity, head and neck, and systemic health are also vitally important. When examining the oral cavity, practitioners may overemphasize a single disease process, such as oral cancer, as the reason for the examination, rather than to ensure that all of the structures are healthy and within normal limits, and that any abnormality—whatever it may be—be discovered as early as possible. By effectively communicating examination and screening procedures, clinicians can greatly improve the perception of the importance of frequent and routine dental care.
The “loss leader” dental office promotions—free exams, free consultations—are often used to entice patients into a practice so more financially profitable procedures can be performed. These promotions have contributed to devaluating the perceived importance, benefit, and reimbursement of a complete and thorough examination for the patients, clinicians, and third-party payers such as insurance providers alike.
This downplaying of the significance of a comprehensive and enhanced examination misrepresents the substantial amount of knowledge, technology, and expertise required to perform these valuable procedures properly.
Patients who believe that the primary importance of a preventive dental/hygiene appointment is to prevent decay and maintain a beautiful smile have missed the real value of a thorough oral examination. Unfortunately, the patient’s perception often is that the primary goal of a check-up is to find a problem which will cost money to fix. However, clinicians who are routinely performing an enhanced head and neck examination, including a tactile exam and an enhanced visual inspection of the oral mucosal tissue using today’s advanced technologies, have the opportunity to change patients’ perceptions.
The Enhanced Examination
The enhanced comprehensive head and neck examination is a multifaceted procedure with many steps (table1). It requires general practitioners to have the knowledge, communication skills, and technical expertise to properly assess every patient in their care. Today’s enhanced screening technologies range from computerized databases, to multi-spectrum visualization tools that allow practitioners to see deeper into soft tissue, to simplified cell and tissue collection techniques. No single modality can deliver 100% accuracy or effectiveness in detecting conditions. Screening and diagnosis is accomplished with the accumulation of data from multiple procedures and sources. Today’s screening and diagnostic aids can have a significant impact on the assessment of a patient’s health and well being.

A patient’s health, pharmacological history, and current status are the foundation of the examination process. Because patients’ systemic and dental health situations are becoming increasingly more complex—with an expanding number of medications—the need for computerized pharmacology and medical condition databases to assist in the patient assessment process is greater than ever. With more than 800 medications that have a xerostomic effect and more than 400 drug formularies changing weekly, clinicians require computerized assistance to stay current. Internet-based systems such as the Lexi-Comp Dental Reference Library™ (Lexi-Comp, Inc., www.lexi.com) provide a collection of interactive databases and reference manuals continually updated as the FDA and drug manufacturers announce changes to their drug information and systemic conditions, with a specialized focus on their relationship to dentistry. This database is designed to allow dental professionals quick and easy access to critical information on drug interactions that influence oral conditions. Its orientation to dental-specific applications helps ensure the correct diagnosis and appropriate care are rendered for each patient’s situation. The complete library also includes a reference manual for the diagnosis and management of oral soft-tissue diseases, providing information on the most common oral conditions divided into sections based on visual appearance (with images of the abnormalities), which assists clinicians in establishing the differential diagnosis. Once a clinical working diagnosis has been attained, suggestions are presented for possible treatment and management.
The demographics, risks, and etiological factors that relate to head and neck cancer and other mucosal abnormalities have changed in recent years. These changes call for enhanced head and neck and oral examinations on all adult patients and others with special considerations (table2). The frequency of human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinoma (OPSCC) is consistently unassociated with dysplasias of the surface epithelium; cervical lymphadenopathy is often the first clinically detectable sign. Thus, it is extremely important that oral healthcare providers carefully perform an extensive extraoral head and neck examination, especially of all cervical lymph nodes

Visual Enhancements for Soft Tissue Evaluation
Visual examination with a standard white light has been the cornerstone of a comprehensive examination. Any noninvasive device that improves the clinician’s visualization and ability to achieve early detection of soft-tissue abnormalities, especially those that are neoplastic in nature, is an invaluable asset to the diagnostic armamentarium. Any visual enhancement device should be used in combination with a conventional visual oral mucosal examination to improve the evaluation, identification, and monitoring of oral mucosa and abnormalities. Available imaging modalities include the use of reflectance and fluorescence technology to evaluate tissue under various illumination conditions.
Fluorescence technology, in particular, is a noninvasive approach for assessing and aiding in the visualization of chemical and morphological patterns of the various tissues and substances within the oral cavity.² Fluorescence visualization enhances the clinician’s ability to observe changes in these patterns and can aid in evaluating both the hard- and soft-tissue structures, as well as the biological activity of the flora and other microbial activity. These technologies do not require the use of any mouth rinses or stains; the process simply repeats the visual exam with the aid of the device(s).
Products such as the VELscope Vx™ (LED Dental Inc., www.velscope.com) and the DentLight Oral Exam Light Kit (DentLight Inc., www.dentlight.com) enable clinicians to visually scan the entire oral cavity for changes in the fluorescence pattern of tissue, which may indicate an area of concern.
The Identafi^® (DentalEZ Group, www.dentalez.com) oral cancer screening device uses a multispectral fluorescence and reflectance technology to enhance visualization of mucosal abnormalities. The small, cordless handheld device uses a three-wavelength optical illumination and visualization system that allows dental professionals to identify oral mucosal abnormalities. Identafi’s three separate wavelengths of light—white, violet, and green-amber—excite oral tissue, providing the clinician three different illumination perspectives to visualize the area being examined. A disposable mirror attachment assists in visualizing the area in an indirect manner.
When an area of concern is discovered through this examination, the clinician needs to ask the appropriate questions to help ascertain the potential cause and the proper course of action. Having a comprehensive understanding of how the technology responds to various conditions, as well as knowledge of the disease processes, will help guide the practitioner to successful outcomes. The clinician must develop a systematic and science-based methodology for handling all of the findings. This underscores the need for thorough education on all the technologies that are being incorporated.
In a retrospective study with 1,317 patients receiving enhanced oral mucosal examination with the use of fluorescence visualization in a private general dental practice over a 2-year period, 460 of the patients (approximately 35%) had a soft-tissue abnormality that was noted in the clinical record. Although none of these patients were diagnosed with oral cancer, 21 of the patients had lesions that were confirmed by a full-thickness biopsy to be dysplastic in nature³ (table 3). The patients with dysplasia were educated on the potential risks of transformation into oral squamous cell carcinoma (OSCC) and advised to eliminate risk factors where possible. These patients were also educated on the need for ongoing surveillance of their condition and scheduled for the enhanced mucosal examination with fluorescence visualization to monitor the condition’s progression or regression on a 3-month recall basis. The remaining patients with soft-tissue abnormalities were counseled and, when appropriate, minor corrective actions were taken and treatment was provided to manage the area of concern. As part of the discussion about proper case management, the need for regular ongoing preventive dental care and surveillance was reinforced.

Microscopic Evaluation and Cytology
Full-thickness surgical biopsy with a microscopic examination is the accepted method of diagnosing cancer and many other mucosal conditions. The role of a biopsy is to rule out a malignancy and to establish the appropriate diagnosis for the patient’s condition. All other modalities, including toluidine blue staining and cytology, are adjunctive procedures to aid in determining if and where a surgical biopsy would be appropriate and most beneficial. Staining and cytology are not substitutes for the traditional “gold standard” surgical biopsy technique of removing architecturally intact tissue. In the majority of cases, a lesion that is worthy of a staining or cytology procedure may be better served by a surgical biopsy that will render a diagnosis.
Another adjunctive screening procedure, brush cytology, involves the collection of transepithelial mucosa cells by means of a minimally invasive sterile, plastic-handled nylon bristle brush—with little or no discomfort to the patient. Disaggregated epithelial cells are acquired by vigorous brushing of the oral lesion with a sterile nylon bristle brush. This technique is used primarily to screen a suspicious leukoplakia or erythroplakia of the mouth in order to aid in determining the presence or lack of premalignant dysplastic change. Brush cytology is an effective system for ruling out the presence of abnormal, atypical, and dysplastic cells in areas that have been properly brushed. The cells are transferred to and fixed on a glass slide or placed in a special liquid preservative/fixative in a bottle; the collected sample is then sent to the laboratory for processing and histological evaluation.
The use of liquid-based cytology in the oral cavity is a relatively new screening technique that has also been proven effective when an area of abnormality has been discovered. Not only can it be used for the detection of dysplastic cells, but it also can be used to detect other oral conditions such as herpes simplex infection and candidiasis. Brush cytology may also aid the clinician in determining if the lesion detected should be observed or treated, or if an immediate invasive full-thickness biopsy procedure with intact architecture should be performed.
Salivary diagnostics has become a reality: patients rinse with specialized solutions and expectorate into a funneled collection tube that is processed and analyzed at the laboratory. Due to the simplicity and noninvasive nature of salivary collection and testing, these screening modalities strongly appeal to clinicians. The saliva that is collected can be evaluated at the laboratory for the status and susceptibility to both oral and systemic conditions. OralDNA^® Labs (www.oraldna.com) has developed salivary tests to determine the patient’s genetic susceptibility to and inherent risk of periodontal disease, as well as a test to identify the type and concentration of 13 pathogenic bacteria that are known to cause periodontal disease. The company’s OraRisk^® HPV test is another noninvasive salivary screening tool to help identify patients who might be at an increased risk for oropharyngeal cancer and to assist in developing the appropriate referral and surveillance recommendations.

Communicating Value
The entire dental team plays a strategic role in the data collection, discovery, diagnostic process, and management (figure 1). From the patient’s very first contact with the dental office, whether it is on the phone, over the practice’s internet portals, or in person, the importance of a consistent message on the value and necessity of an enhanced oral examination cannot be overstated. Properly communicating the real purpose of these procedures is extremely important in changing patients’ perceptions of the enhanced examination techniques and helping them realize the significant benefits involved.
Effective communication is a critical component of the examination process. When clinicians inaccurately state that they are going to do an “oral cancer exam,” it implies that cancer is the only thing they are looking for. After they have explained it in this manner, no matter how clinicians present their findings, it can cause the patient undue anxiety. If any abnormality is found the patient often perceives it as possibly cancer, especially if the area of concern requires follow-up attention or treatment.
The goal of an enhanced examination and screening is to discover any abnormality, no matter what it may be. A more appropriate way to present and discuss the exam with patients is to tell them that an enhanced oral evaluation is going to be done, in which all of their teeth and surrounding structures will be examined, and everything will be checked, from cavities, to cheek bites, to cancer.
When incorporating any new technology into a dental practice, education and training that encompasses the entire dental team is crucial to understanding specific technologies, their true role and value, and, even more importantly, their limitations. Because most patients first turn to the office’s staff for advice and comforting regarding a procedure, the value of education for the entire team cannot be overstated.

Conclusion
The significance of the diagnostic process continues to be undervalued by patients and clinicians alike. Despite the fact that there is an ADA code on dental procedures and nomenclature (CDT) for an “adjunctive pre-diagnostic test,” the lack of insurance coverage impedes the adoption and acceptance of these advanced diagnostic technologies and procedures. However, it is the practitioner’s responsibility to use all modalities that are reasonably available to accomplish the best outcomes for the patients.
The incorporation and proper utilization of appropriate advanced diagnostic technologies is essential as dentistry moves forward into the medical and wellness model. Understanding and properly communicating the full benefit that the enhanced examination and other diagnostic procedures will provide for the patient is imperative. After all, the goal of all healthcare professionals is to facilitate better patient outcomes and to enhance and improve the patient’s quality of life.

Headache Orofacial Pain and Bruxism

2011-09-24T18:37:00.001+03:00

Hardcover Reference
400 Pages
Imprint: Churchill Livingstone
ISBN: 978-0-443-10310-0
Download

Esthetic and Cosmetic Dentistry for Modern Dental Practice: Update 2011

2011-09-23T21:56:00.000+03:00

Dental Clinics of North America
April 2011 issue
Wonderful articles on aesthetics,ortho,bleachng,ceramics and many more.....
download

Contemporary Concepts in the Diagnosis of Oral and Dental Disease

2011-09-23T20:56:00.000+03:00

Dental clinics of North America
January 2011 issue
Diagnosis is the essential first step in the provision of health care. A patient presents to a health care provider for a routine evaluation or with a specific complaint requiring attention. The provider will review the health history, ask pertinent questions about the history and symptoms, and then examine the patient. This will be followed by the use of other diagnostic procedures and tests, which can include radiographic studies and analysis of biologic fluids and tissue samples. Arriving at the correct diagnosis allows for selection of appropriate treatment, with minimal time delay. Health care providers must continually seek to improve their diagnostic acumen.
download

Essentials of Microbiology for Dental Students

2011-09-23T19:35:00.001+03:00

Book information
Paperback: 348 pages
Publisher: Oxford University Press, USA; 2 edition (February 2, 2006)
Language: English
ISBN-10: 0198564899
ISBN-13: 978-0198564898
Product Dimensions: 10.8 x 8.7 x 0.9 inches
download

INGLE'S ENDODONTICS 6 EDITION (2008)

2011-08-23T19:13:00.000+03:00

The 6th Edition of Endodontics is replace with new innovations and knowledge.Now more than ever,it remains the "BIBLE OF ENDODONTICS" a name long applied to the previous editions.
Ingles Endodontics 6 is the ultimate endodontic textbook-an essential edition to every endodontist's library and the standered against which all other endodontic texts are measured........
Download