dentoverse

Matrix metalloproteinases (MMPs) in dentistry

2011-07-23T03:20:00.000-07:00

Matrix metalloproteinases (MMPs) are a family of zinc- dependent endopeptidases that degrade a variety of extracellular matrix components. They play important roles in tissue morphogenesis, development and remodelling. The MMPs are secreted in latent forms (pro-MMP) and activated extracellularly. Their expressions and activities are regulated by the interaction with specific tissue inhibitors of metalloproteinases (TIMPs).

Imbalance between activated MMPs and their TIMPs results in pathological destruction or accumulation of the extracellular matrix.Certain MMPs and TIMPs have been identified in human tooth structures and reported to play different roles in various physiological and pathological processes during human dentine—pulp complex formation and maintenance. Among these MMPs, the distribution of gelatinases with collagen-degrading ability (i.e., MMP-2 and MMP-9) and their inhibitors is of particular interest because of their important roles in tooth formation and mineralization, as well as in the process of caries progression and degradation of dentine hybrid layers.

REF : JOURNAL OF DENTISTRY 39 , 2011.

methods to determine polymerisation shrinkage

2011-07-18T10:12:00.000-07:00

Dilatometry,
modified bonded disk,
strain gage,
linear transducer,
gas pycnometer

REF: Dental Materials (2004) 20

irrigation system ( soni care canal brush )

2011-07-15T21:27:00.000-07:00

The Sonicare CanalBrush is a combination of a newly designed intra-canal polypropylene brush inserted into a Philips Sonicare Elite toothbrush (Philips, Amsterdam, Netherlands). The sonic toothbrush operates at a frequency of 50 Hz and performs 31 000 strokes per minute. The head of the original Sonicare Elite toothbrush was altered to hold the CanalBrush. The Sonicare achieves brush velocity with a combination of high frequency and high amplitude brush motion. This velocity generates dynamic action but is gentle on the root canal walls. The Canal Brush has a total length of 41 mm. Its contra angle shaft of 15.34 mm includes the acting 16 mm component that contains the bristles. The 30 bristles are <0.40 mm long and arranged opposite to each other with an inter-bristle distance of 0.50 mm. The bristle tip has a diameter of 0.25 mm, and the core increases with a taper of 2%. The acting part of the bristle starts approximately 1 mm behind the tip.

Technique for measuring root canal curvature (schneider method )

2011-07-15T17:07:00.000-07:00

The angle of the curvature was first determined by Schneider (1971). He determined by marking certain points like point A which denotes the apical foramen. The point where the canal begins the curvature is marked as point B. A line is then drawn parallel to the long axis of the canal through point B, and a point C is chosen on this line such that the distance between B and C is equal to that between A and B. The angle formed by lines AB and BC is the angle of curvature.

From E and F, the midpoints of AB and BC, respectively, two lines are drawn perpendicular to the lines AB and BC, which would meet at the circumcentre 0 of triangle ABC. The distance between 0 and A, B or C is the radius (K) of the circumference, which determines the magnitude of the curve.

PROCEDURE FOR LUTING OF CERAMIC TO TOOTH STRUCTURE

2011-07-14T15:36:00.000-07:00

Surface conditioning of ceramic using
hydroflouric acid gel
or air abrasion .

Aplication of silane coupling agent . ex : MONOBOND S ( ivoclar , germany )

Followed by the application of resin luting cement . ex : rely x unicem , clearfil se etc

REVITILISATION OF NON VITAL TOOTH USING PLATELET RICH PLASMA ( PRP )

2011-07-09T03:21:00.000-07:00

Initially the tooth to be treated should be administrated with local anesthesia access cavity is prepared. On entry into the root canal. The necrotic pulp should be removed with the aid of a large barbed broach. The working length was determined using an apex locator EX : Elements,sybron endo.) . The canal should be irrigated with approximately 10 ml of 5.25% NaOC1 and dried with paper points. Equal proportions of ciprofloxacin, metronidazole, and minocycine should be ground and mixed with distilled water to a thick paste consistency. This antibiotic mixture should be than placed in the canal using an amalgam carrier and packed with large endodontic pluggers. After which the access cavity was sealed with Cavit ( 3M,ESPE, France).

A 20-ml sample of whole blood should be drawn from the patient’s right arm for platelet rich plasma (PRP) preparation. PRP is prepared by mixing SmartPReP2 APC+ Autologous Platelet Concentrate+ Procedure Pack (Harvest Technologies Corp, Plymouth, MA) with the Harvest SmartPREP 2 Platelet Concentrate System (Harvest Technologies Corp).

During the next appointment, the teeth should be isolated with a rubber dam, the temporary restoration should be removed, and the antibiotic mixture was washed out by using sterile saline irrigation. The canal was dried with paper points. Prepared PRP should be then injected into the canal space up to the level of the cemento -enamel junction (CEJ) and allowed to clot for 5 minutes. 3mm of white MTA (Pro- Root MTA; Dentsply )was placed directly over the PRP clot. A moist cotton pellet was placed over the MTA and finally restored with GIC ( GC corp,japan.).

REF:JOE,37,2011.

SILICONE BASED SEALER .(ROEKO SEAL)

2011-07-08T21:45:00.000-07:00

It is a silicone based sealer.

It consists of polydimethyl siloxane, silicon oil, paraffin-base oil, hexachloroplatinic acid (catalyst) zirconium dioxide.

It is supplied in a dual tube syringe which is ready to use.

It has excellent biocompatibility.

Less microleakage.

REF: J.ORAL.REHAB,2003

SOLVENTS FOR DISSOLVING GUTTA PERCHA

2011-07-08T09:20:00.000-07:00

eucalyptol
xylene/xylol
methyl chloroform
tetrahydrofuran
methylene chloride
halothane
rectified turpentine and
orange solvent

REF: Endodontic Topics 2011, 19, 33–57

TECHNIQUE FOR FABRICATION OF CUSTOM MADE POST WITH METAL POST AND CERAMIC CORE

2011-07-08T05:10:00.000-07:00

Post space preparation should be completed first. Make a keyway at the coronal end of the root canal to provide adequate metal and ceramic thickness.

Select an appropriate size prefabricated plastic burnout post pattern to the prepared root canal and leave an extension for the retention of ceramic core. After lubrication of the root canal, reline the plastic post with a self curing acrylic resin material to ensure an optimal adaptation to the canal.

Finish line should be a rounded shoulder, which will provide adequate ceramic thickness.

Cast the post using a porcelain metal alloy and coat the core extension with opaque ceramic to mask the metal.

Verify the fit of the post in the canal and build up the core with self curing acrylic resin. Once the resin has polymerized, prepare the core pattern in the usual manner for an all-ceramic crown .

Remove and invest the resin core with the cast metal post. After the burnout and preheating process, heat-press the core from leucite reinforced glass-ceramic (ex : IPS impress , ivoclar , germany ) with the desired shade

After verifying the fit, cement the metal post and ceramic core assembly using a self-curing resin cement. The post-and-core is ready to undergo impression for the all-ceramic crown.

Finally cement the finished all-ceramic crown to the core.

REF : Dental Traurnatology ,21, 2005.

HORIZONTAL ROOT FRACTURE ( MANAGEMENT- intra -radicular splinting )

2011-07-07T09:33:00.000-07:00

First root canal treatment should be initiated. A no. 15 K file should be passed through the fracture and the apical root segment should be accessed. Then the fractured tooth should be fixed rigidly using a dentin-bonded composite resin (EX : Filtek Z250, 3M ESPE.),with the adjacent teeth.The root canal should be cleaned, shaped and enlarged to a size of file 70,and the canal should be filled temporarily for 3 months with calcium hydroxide paste.

After three months, the dressing should be carefully removed from the canal, and the canal was enlarged to no. 110 K file size. Any resin root canal sealer (EX : AH PLUS Dentsply, Germany) should be introduced into the canal using a K file. Zinc polycarboxylate cement should be mixed and placed in the canal with a lentulo spiral carefully and then a no. 110 K file should be coated with polycarboxylate cement and fixed in the canal. After the polycarboxylate cement set, the hand part of the K file should be cut away using diamond round burs on a high-speed air turbine with water-cooling. The endodontic access cavity should be then filled with the dentin-bonded composite resin.

REF : Dental Traurnatologv ,24,2008.

VENEERS ( CLASSIFICATION )

2011-07-07T02:52:00.000-07:00

Veneers can be basically classified in to two types

partial veneers
full veneers.

Partial veneers are indicated for the restoration of localized defects or areas of intrinsic discoloration .

Full veneers are indicated for the restoration of generalized defects or areas of intrinsic staining involving the majority of the facial surface of the tooth.

Full veneers can be further subdivided in to two types based on tooth preparation.

Full veneer with window preparation design that extends to gingival crest and terminates at the facioincisal angle.

Full veneer with i ncisal-lapping preparation design extending subgingivally that includes all of incisal surface.

Full veneers can be accomplished by a direct or an indirect technique.

REF: ART AND SCIENCE OF OPERATIVE DENTISTRY -STURDEVENT

PINS FOR AMALGAM RESTORATION ( CLASSIFICATION )

2011-07-07T00:31:00.000-07:00

There are three types of pin available for retention of amalgam restoration namely

Self-threading pin,
Friction-locked,
Cemented pins.

The pin-retained amalgam restoration using self-threading pins was originally described by Going in 1966. The diameter of the prepared pinhole is 0.0015 inch to 0.004 inch smaller than the diameter of the pin. However, a general guideline for pinhole depth is 2 mm.

Several styles of self-threading pins also are available. Out of which the Thread Mate System (TMS) (Coltene/Whaledent Inc.) is the most widely used self-threading pin.

Four sizes of TMS pins.

Regular ( 0.031 inch [0.78 mm])--gold
Minim (0.024 inch [0.61mm])-- silver
Minikin (0.019 inch [0.48 mm])-- red
Minuta ( 0.015 inch [0.38 mm])--pink

It was Markley in 1958 described about cemented pins. They are cemented into pinholes prepared 0.001 to 0.002 inch (0.025 to 0.05 mm) larger than the diameter of the pin. The cementing medium may be any dental luting cement.

In 1966, Goldstein" described a technique for the friction-locked pin in which the diameter of the prepared pinhole is 0.001 inch (0.025 mm) smaller than the diameter of the pin

REF: ART AND SCIENCE OF OPERATIVE DENTISTRY--- STURDEVENT

CRACKED TOOTH SYNDROME ( diagnostic aids )

2011-07-06T05:41:00.000-07:00

Kind of vertical fracture extending in to the enamel and some times in to dentin presenting the character of both reversible and irreversible pulpitis.Can be diagnosed using the following methods.

Dyes ( methylene blue )

Cotton

Tooth sloth

Transillumination

BISPHOSPHONATES (IN DENTISTRY)

2011-07-06T03:22:00.000-07:00

Bisphosphonates (BPs) are widely used drugs for patients with bone disorders showing increased osteoclast activity, such as Paget’s disease, hypercalcemia of malignancy, and osteoporosis.

Depending on the content of BPs in molecular level, BPs can be divided into

NON-NITROGEN CONTAINING BPs, such as clodronate, etidronate, tiludronate.

NITROGEN- CONTAINING BPs, such as alendronate, pamidronate, risedronate, and zoledronate.

There have been many studies investigating the use of BPs during dental trauma mainly focusing on the use of alendronate and etidronate by means of topical root treatment and intracanal agents. Topical application of alendronate has been shown to decrease root apex inflammation and inhibited root resorption in delayed replanted animal teeth.

REF: Dental Traurnatologv ,26,2010.

TEETH RE -ATTACHMENT PROCEDURE (MODIFIED SIMONSEN METHOD)

2011-07-06T02:56:00.000-07:00

Teeth fragment and remaining crown were prepared as follows:

Notches of 1 1.5 mm on approximal sides within the enamel were made by using a No. 1 round diamond bur in both of the fragments and in the remaining crown (these fragments were placed on a wax bar for easier manipulation).Notches were made in order to guide the correct adaptation of tooth fragments. And a bevel of 45 degree measuring about 1.5mm wre made on the enamel margin of the remaining crown.

Both the fragments and the remaining dental structures were acid etched using 37% orthophosphoric acid for 30 s for the enamel and 15 for the dentin; the acid was eliminated by rinsing with distilled water and drying.

Dental adhesive was applied to both the fragments and the teeth and light cured for 40 sec

A flowable resin (EX; Tetric Flow, Ivoclar Vivadentor ) was used to adhere the fragments to the teeth; a thin layer of this resin was placed in the notches and across the fractured surface of the teeth to allow for a small excess of material when the fragments were repositioned, then flowable resin was light cured for 60 sec labially and palatally.

Finally, the excess at the restorative margins were finished and polished with

finishing burs and discs.

REF : Dental Traurnatologv ,27 ,2011.

BIOACTIVE MATERIAL ( BIO DENTINE -from septodent )

2011-07-05T22:20:00.000-07:00

Biodentin (septodent ) is a new dentine subsitute based on Active Biosilicate Technology designed to treat damaged dentine .

It consists of Tricalcium Silicate core.

Biodentine needs no dentine surface conditioning, no bonding and exhibits excellent sealing properties to reduce the risk of bacterial percolation, thus preventing post-operative sensitivity.

Biodentine can safely be used in the crown as a bulk restorative material in direct and indirect pulp cappings, pulpotomies or deep cavities and kept as a temporary enamel restoration, perforations, internal/external resorptions, apexification and retrograde surgical filling.

Biodentine consists of 15 capsules and can be mixed in any amalgamator with a minimum speed of 4,000 rpm.

NONTHERMAL ATMOSPHERIC PRESSURE PLASMA ( for bleaching )

2011-07-05T07:36:00.000-07:00

Plasma is the fourth state of matter. It consists of charged particles, radicals, and a strong electric field, so that it is a highly reactive material. Since a plasma jet device generates plasma in the surrounding air at low temperature, it is suitable for direct treatment of target teeth. Furthermore, the produced energetic ions, free electrons, and hydroxyl radicals (OH) from the plasma contribute significantly to tooth bleaching; thus, plasma might shorten the bleaching period because of its synergistic effects on tooth bleaching.

THE DEVICE

The nonthermal atmospheric pressure plasma jet device consists of a Teflon tube,that has an inner and an outer aluminium electrode. The outer electrode is connected to a 20 kHz voltage source with a 5 KV voltage. The inner electrode is suspended and not connected to any external power source. It consists of an aluminium cylinder perforated by capillary holes of 1 mm in diameter. Helium gas with a flow rate of 2 L/min is used as feeding gas though the Teflon tube at atmospheric pressure in air. The plasma generation occurs inside the Teflon tube near the powered outer electrode. Subsequently, the plasma is driven out by helium flow to generate a plasma jet outside the Teflon tube in atmospheric pressure air. The jet length increases with the flow rate or applied voltages, and it can reach 3 cm in air.

REF : IEJ, 44, 2011

FLUORIDE RECHARGE

2011-07-05T05:55:00.000-07:00

Fluoride-releasing materials can take up fluoride ions from the oral environment as a means of replacing fluoride which has been lost. The recharge of fluoride may contribute to the ability of these materials to provide a long-term inhibitory effect on enamel demineralization, because the recharged fluoride is released again and presumably contributes to continuous prevention of enamel demineralization.

In addition, the recharge capacity could be significantly influenced by different recharging protocols. Some of the fluoride recharging protocols are application of fluoride varnish, or tooth paste.

REF: JOURNAL OP DENTISTRY ,39 ,2011

LASERS IN DENTIN HYPERSENSITIVITY (mechanism of action )

2011-07-05T05:37:00.000-07:00

Various laser types have been used for dentin hypersensitivity (DH) treatment, including neodymium- or erbium-doped yttrium-aluminum garnet (Nd:YAG and Er:YAG), C02, He-Ne(helium – neon ) and diode ( GaAIAs – gallium aluminium arsenide) lasers, with various energy settings and with wavelengths ranging from 632 nm (He-Ne) to 10,600 nm (Er:YAG, C02).

For low output-power lasers (ie, diode lasers , He-Ne ), the desensitizing effect seems to be related to laser activity at the nervous level. For example, the He-Ne laser does not affect peripheral A delta or C fiber nociceptors but acts on electric activity . Similarly, the GaAIAs laser seems to depolarize afferent C fibers.

The desensitizing effect of the middle output-power lasers (Nd:YAG, C02, and Er:YAG) is thought to be related to the occlusion or narrowing of the dentinal tubules. it vapourizes the water presnt in dentin ,during which the bubbles break there by melting the dentin and occludes the dentinal tubules. this process is termed as spallation.

REF: JOE ,37, 3, 2011

CERA BUR ( SMART BUR )

2011-07-03T07:49:00.001-07:00

Cera Bur (Komet-Brasseler, Germany) is a self-limiting ceramic bur (alumina-based with stabilized zirconia) , which according to the manufacturer efficiently cuts infected, soft dentin, while hardly acts on hard, sound tissue.

REF; DENTAL MATERIALS ,27,2011.

LEDERMIX PASTE

2011-07-03T07:28:00.001-07:00

Ledermix (Lederle Pharmaceuticals, Germany), a corticosteroid ( triamcelone acetonide ) /tetracycline water-soluble paste, is an effective antibacterial and anti-inflammatory medicament that promotes favorable periodontal healing and inhibits EIRR ( external inflammatory root resorption ) after the experimental avulsion and replantation.

REF: JOE — 35, 5, 2009

CHELATING AGENTS ( mechanism of action )

2011-07-03T07:07:00.000-07:00

The two main action of a chelating agent is

1. Complex formation

2. protonation.

REF: IEJ,36,2003

GUTTAFLOW

2011-07-02T11:49:00.001-07:00

It was Coltène/Whaledent in 2004 introduced a flowable, self-curing obturation material for root canals that combines gutta-percha and sealer into one injectable system. Guttaflow contains gutta-percha in particle form combined with a polydimethylsiloxane-based sealer. GuttaFlow is available in a capsule and can be injected directly into the canal. It is used in combination with a master gutta-percha cone and does not require any form of manual compaction for placement. The material is believed to flow into lateral canals and completely fill the space between the root canal wall and the master cone. In addition the manufacturer claims that the material expands 0.2% upon curing.

REF: JOE , 34, 2008

RECIPROC ( ONE ISTRUMENT FOR ENTIRE ROOT CANAL TREATMENT )

2011-07-02T09:45:00.000-07:00

Only one instrument to prepares the entire root canal .

Available in three sizes (25,40,50) and length ( 21 ,25 ,31mm )

Made from M -wire technology.

No need to change instruments

No need to establish the glide path .

The risk of instrument fracture is minimised due to precise reciprocation settings in the reciproc motor

Safer for patient and personnel ,due to pre-sterilised, single-use instruments

Manufactured by VDW

FIBREFILL

2011-07-02T05:12:00.000-07:00

Fibre fill (Pentron Clinical Technologies ) is a combination obturation technique in which the apical 5 to 8 mm of the system is gutta-percha and the coronal two thirds consist of a resin core post. The entire system is sealed with a resin sealer after the canal wall is prepared with a primer and bonding agent. Finally core is built over the post and retained with a coronal restoration.

JOE : 30,2004