NARAYANA DENTAL COLLEGE AND HOSPITAL DEPARTMENT OF CONSERVATIVE DENTISTRY AND ENDODONTICS
R oot ca n a l s ea l er s
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CONTENTSINTRODUCTION REQUIREMENTS OF ROOT CANAL SEALER SELECTION OF ROOT CANAL SEALER CLASSIFICATION Eugenol Based Root Canal Sealer Kerrs Sealer (Ricketts Formula) Grossmans Sealer Wachs paste Sealer Tubliseal Non-eugenol Root Canal Sealer Chloropercha Nogenol Calcium Hydroxide Calcibiotic root canal sealer Seal Apex Life Apexit Vitapex Powders and Resins Diaket AH-26 AH-plus Endofill Glass Ionomer (Ketac-Endo) Formaldehyde containing root canal sealer Experimental root canal sealer EFFICACY OF ROOT CANAL SEALER TISSUE TOLERANCE OF ROOT CANAL SEALER STUDIES RELATED TO ROOT CANAL SEALER
INTRODUCTIONThe sealer plays an important role in the obturation of root canal. The Sealer fills all the space the gutta percha is unable to fill because of gutta-perchas physical limitations. The sealer acts as a binding agent, to the dentin and to the core material, which usually is gutta percha. The sealers are usually a mixture that hardens by chemical reaction, such reaction normally includes the release of toxic material, making the sealer less biocompatible. Several sealer and cements, such as AH-26, AH-Plus, KetacEndo and Diaket may be used as the sole filling material because they have sufficient volume stability to maintain a seal. Under such preventing excess is often difficult because the sealer is applied with a lentulo spiral. There are a variety of sealers from among which to choose and the clinician must be careful to evaluate all characteristics of a sealer before selecting. Sealer helps to fill in irregularities and minor discrepancies between the filling and canal walls, accessory canals and multiple foramina. Sealer discloses the presence of ancillary canals, resorptive areas, root fractures, shape of the apical foramen and other structures due to its radio-opacity. A sealer is a good lubricant and helps in the seating of primary cone into the canal. It is a good germicidal or antibacterial.
REQUIREMENTS FOR AN IDEAL ROOT CANAL SEALER: It should be tacky when mixed to provide good adhesion between it and the canal wall when set. It should make a hermetic seal. Sealers should have ample setting time, giving the clinician sufficient time to make necessary adjustments to the filling material. The particles of powder should be very fine so they can mix easily with the liquid. It should not shrink upon setting All the Sealers shrink slightly upon setting and gutta percha also shrinks when returning from a warmed of plasticized state. It was found that zinc oxide eugenol sealers begin shrinking within hours after mixing, but that AH-26 and Endo-fill first expanded and showed no shrinkage for 30 days. The least dimensional change at any time was observed for Endo-fill. Significant dimensional change and continued volume loss can occur in some endodontic sealers. Sealers should not stain tooth structure. The admonition that sealers and filling materials should not stain tooth structure, Grossmans requirement is evidently being violated by a number of sealers. Vander Burgt from Holland and her associates reported, Grossmans cement, zinc-oxide eugenol, Endomethasone, and N2 induced a moderate orange red stain to the crowns of upper premolar teeth.
She further found that Diaket and Tubliseal caused a mild pink discoloration whereas AH-26 gave a distinct color shift towards gray. On the other hand Rieblers paste caused a severe dark red stain. Diaket caused the least discoloration. As far as the staining ability of other materials is concerned, Vander Burgt found that Cavit produced a light to moderate yellowish /green stain that gutta percha caused a milk pinkish tooth discoloration, that AH-26 Silver free and Duo Percha induced a distinct color shift towards gray and that crowns filled with IRM and Dycal became somewhat darker. No discolorations were recorded for teeth filled with Durelon, Fuji glass ionomer, Fletchers cement, or zinc phosphate cement. Sealers that contain silver as radio opacifier, such as Kerrs Root Canal sealers (Ricketts Formula) or the original AH-26 are notorious as tooth strainers. It should be bacteriostatic, or at least not encourage bacterial growth. Grossman tested 11 root canal cements and concluded that they all exerted antimicrobial activity to a varying degree, those containing para-formaldehyde to a greater degree initially. With time however, this latter activity diminished so that after 7 to 10 days the formaldehyde cements were no more bactericidal than other cements.
6 More recently a British group studying the antibacterial activity of four restorative materials reached much the same conclusion regarding zinc oxide eugenol and glass ionomer cement. Another study founded that 10 sealers inhibited growth of streptococcus sanguis and streptococcus mutans. A Temple university study found that Grossmans sealer had the greatest overall antibacterial activity, but that AH-26 was the most active against bacteroides endodontalis, an anaerobe. Sealers should be insoluble in tissue fluids. Smith and McComb found a wide variance in sealer solubility after 7 days in distilled water, ranging from 4% for Kerrs pulp canal sealer to much less than 1% for Diaket. Peters found after two years that virtually all the sealer was dissolved out of test teeth filled by lateral or vertical compaction. Therefore most sealers are soluble to some extent. It should set slowly. It should be tissue tolerant that is non-irritating to
periradicular tissue. Para formaldehyde containing sealers appear to be the most toxic and irritation to tissue. A case in point is reported from Israel necrosis of the soft tissue and sequestration of crestal alveolar bone from the leakage of para formaldehyde paste from a gingival level perforation.
It should be soluble in a common solvent if it is necessary to remove the root canal filling.
It should not provoke an immune response in periradicular tissue.
It should be neither mutagenic nor carcinogenic.
SELECTION OF SEALER For use with gutta-percha, appropriate sealers should be selected to aid in the filling of the canal. The operator should determine the amount of lubrication needed, the length of working time estimated, and the filling material to be used before deciding which sealer or sealers would best perform the necessary function. In lateral condensation methods use of sealer should be minimal, since the compressible filling material will be able to fill most irregularities. All the sealers have resorbable properties when expressed into periapical tissue, although rarely has resorption of the sealer within the canal been noted. Still, it is preferable to seal a canal with the packed solid-core material, which is largely unresorbable, as compared to the sealer. A good sealer should be biologically compatible and well tolerated by the periapical tissues. All sealers are highly toxic when freshly prepared; however their toxicity is greatly reduced after setting takes place. A few days after cementation practically all root canal sealers produce varying degrees of periapical inflammation (usually temporary); this usually does not appear to prevent tissue healing and repair.
Although most cement sealers were highly irritating to periapical tissues, the most severe alveolar and bone destruction was caused by poor debridement and poor filling of the root canal system. Minimal tissue reaction was found when the canal was not over-filled. Over instrumentation and overfilling caused immediate periapical inflammation, which tended to persist and to cause epithelial proliferation and cyst formation. In teeth filled short of the foramen, the reaction was temporary and complete repair eventually took place. ROOT CANAL SEALER CEMENTS In most clinical situation, core materials are used with root canal sealer cement. The bond between the sealer and the core material is non-adhesive. The core and sealer root canal filling techniques involve 2 inter phases one between the core and the sealer and the other between the sealer and dentin. Root canal sealer cements are divided into: 1) Eugenol based cement 2) Non-Eugenol based cement EUGENOL BASED SEALER CEMENTS Many root canal cements are based on zinc oxide eugenol, which is known to provide a good seal. Many endodontic sealers are simply zinc oxide eugenol cements that have been modified for endodontic use.
9 The mixing vehicle for these materials is mostly eugenol. The powder contains zinc oxide that is finely sifted to enhance the flow of the cement. Setting time is adjusted to allow for adequate working time. One millimeter of zinc-oxide eugenol cement has a radioopacity corresponding to 4-5 mm of aluminum, which is slightly lower than gutta-percha. These cements easily lend themselves to the addition of chemicals and para-formaldehyde is often added for antimicrobial and mummifying effects, germicides for antiseptic action, rosin or Canada balsam for greater dentin adhesion, and corticosteroids for suppression of inflammatory reaction. Zinc oxide eugenol sets because of the combination of chemical and physical reaction, yielding a hardened mass of zinc oxide embedded in a matrix of a long sheath like crystals of zinc eugenolate [C10 H11 O2]2 Zn. Excess eugenol is invariably present and is absorbed by both zinc oxide and eugenolate. The presence of water, particle size of the zinc oxide, the pH and the additives are all important factors in the setting reaction. Hardening of the mixture is due to zinc eugenolate formation; unreacted eugenol remains trapped and tends to week and the mass. All zinc oxide eugenol cements have an extended time but set faster in the tooth than the glas