Lecture 7 - Simplyifing Endodontics with Hussain Al-Huwaizi 2 PDF

Endodontics Lecture 7 ‫حسين فيصل الحويزي‬.‫د‬.‫أ‬ Root canal filling materials Sealers They are paste like material that is essential to seal the space between the dentinal wall and the gutta percha. Functions of the root canal sealer 1Cementing the core material to the canal wall. 2Filling and mark...

Endodontics Lecture 7 ‫حسين فيصل الحويزي‬.‫د‬.‫أ‬ Root canal filling materials Sealers They are paste like material that is essential to seal the space between the dentinal wall and the gutta percha. Functions of the root canal sealer 1Cementing the core material to the canal wall. 2Filling and marking irregularities that can not be filled by gutta percha (lateral and accessory canals). 3Act as a lubricant to ease the placement of the master cone. 4Act as a bactericidal agent. Properties of an Ideal Sealer 1Exhibits tackiness when mixed to provide good adhesion. 2Produce a hermetic seal. 3Radiopaque. 4Very fine powder to get a smooth mix with the liquid. 5No shrinkage on setting. 6No staining of tooth structure. 7Bacteriostatic. 8Exhibits a slow set. 9Insoluble in tissue fluids. 10Tissue tolerant. 11Soluble in common solvents. Zinc Oxide and Eugenol Zinc oxide–eugenol sealers have been used for many years. They have certain properties as: 1Exhibit a slow setting time. 2Shrinkage on setting. 3Solubility especially when extruded outside the root canal. 4Stain tooth structure. 5It has antimicrobial activity. Types of zinc oxide eugenol sealers 1Rickert sealer. This powder/liquid sealer contains silver particles for radiopacity. It stains tooth structure if not completely removed. This sealer is popular when using thermoplastic techniques. 2Procosol sealer. It is a modification of Rickert’s formula in which the silver particles have been removed. 3Roth's sealer. This is a modification of the Rickert' sealer as it is nonstaining. 4Tubli-Seal. It is a catalyst/base zinc oxide–eugenol sealer. It has a faster setting time when compared with the liquid/powder sealers. Calcium Hydroxide Sealers. They were developed for their antimicrobial activity and osteogenic–cementogenic potential. These actions were very limited. From the types of this group are Sealapex (catalyst/base system), Apexit and Apexit Plus. Noneugenol Sealers. They are root canal sealers without the irritating effects of eugenol. Glass Ionomer Sealers. The glass ionomers have been developed in root canal obturation because of their dentin-bonding properties. An example from this group is Ketac-endo. Properties of this group: 1It enables adhesion between the material and the canal wall. 2It is difficult to properly treat the dentinal walls in the apical and middle thirds with modifying agents to receive the glass ionomer sealer. 3It has minimal antimicrobial activity. Resin resin sealers. These sealers provide adhesion, and do not contain eugenol. Types of this group are: 1Ah-26. It is a slow-setting epoxy resin that releases formaldehyde when setting. 2Ah Plus. It is a modified formulation of Ah-26 in which formaldehyde is not released. It exhibits a working time of approximately 4 hours. 3EndoreZ. It is a methacrylate resin with hydrophilic properties. When used with endoreZ resin-coated gutta-percha cones the dual cure endoreZ sealer bonds to both the canal walls and the core material. 4Diaket. It is a polyvinyl resin sealer. 5Epiphany and RealSeal. They were introduced for use with the resilon filling material. Silicone Sealers. 1RoekoSeal is a polyvinylsiloxane that is supposed to expand slightly on setting. 2GuttaFlow is a cold flowable matrix that is triturated. It consists of guttapercha added to roekoSeal. Sealing ability is comparable to other techniques. Bioceramic sealers. It is composed of zirconium oxide, calcium silicates, calcium phosphate monobasic, calcium hydroxide, and various filling and thickening agents. Properties of this group: 1It is a hydrophilic sealer it utilizes moisture within the canal to complete the setting reaction. 2It does not shrink on setting. 3It is biocompatible. 4It exhibits antimicrobial properties during the setting reaction. Semi Rigid types materials for obturation of the root canal 1- Gutta-Percha Gutta-percha is the most commonly used root canal filling material. It is a linear crystalline polymer that melts at a set temperature, with a random but distinct change in structure resulting. It occurs naturally as 1,4- polyisoprene and is harder, more brittle, and less elastic than natural rubber. The crystalline phase has two forms, the alpha phase and the beta phase. The alpha form is the material that comes from the natural tree product. The processed, or beta, form is used in gutta-percha for root fillings. When heated, gutta-percha undergoes phase transitions. The transition from beta phase to alpha phase occurs at around 46° C. An amorphous phase develops at around 54° C to 60° C. When cooled very slowly gutta-percha crystallizes to the alpha phase. Normal cooling returns the gutta-percha to the beta phase. Gutta- percha cones soften at a temperature above 64° C. These cones can easily be dissolved in many solvents as chloroform, halothane and xylene. Modern gutta-percha cones that are used for root canal fillings contain only about 20% gutta-percha. The major component is zinc oxide (60% to 75%). The remaining 5% to 10% consists of various resins, waxes, and metal sulfate. Antiseptic gutta-percha with various antimicrobial agents as chlorhexidine and calcium hydroxide may be seen. Gutta-percha cannot be heat sterilized, therefore NaOCl can be used to disinfect the cones by dipping them for 1 minute. Pressure applied during root canal filling procedures does not compress gutta-percha, but rather compacts the gutta-percha cones to obtain a more three- dimensionally complete fill of the root canal system. After heating, while cooling, there is a slight shrinkage of approximately 1% to 2% when the gutta-percha has solidified. Gutta-percha cannot be used alone as a filling material; it lacks the adherent properties necessary to seal the root canal space. Therefore, a sealer is always needed for the final seal. Gutta-percha cones are available in tapers matching the larger tapered rotary instruments (#.02, #.04, and #.06). Advantages of gutta percha 1Inert 2Dimensional stability 3Non allergic 4Antibacterial 5Non staining to dentin 6Radiopaque 7Compactable 8Softened by heat 9Softened by organic solvents Disadvantages of gutta percha 1Lack of rigidity 2No adherence to dentin 3No complete adaptation to narrow areas. 2- Resilon It is a thermoplastic, synthetic, polymer-based root canal filling material. It was developed to create an adhesive bond between the solid-core material and the sealer. Resilon can be supplied in the same ISO sizes and shapes (cones and pellets) as gutta- percha. When manufactured in cones, Resilon’s flexibility is similar to that of guttapercha. Based on polyester polymers, Resilon contains bioactive glass and radiopaque fillers (bismuth oxychloride and barium sulfate) with a filler content of approximately 65%. It can be softened with heat or dissolved with solvents such as chloroform. Mineral trioxide aggregate (MTA) It was developed for use as a dental root repair material by Dr. Mahmoud Torabinejad and was formulated from commercial Portland cement combined with bismuth oxide powder for radiopacity. MTA is used for: 1- Creating an apical plug during apexification. 2- Repairing root perforations during root canal therapy. 3-Treating internal root resorption. 4- Root-end filling material. 5- Pulp capping material. Composition MTA is composed of: 1- tricalcium silicate. 2- dicalcium silicate. 3- tricalcium aluminate. 4- tetracalcium aluminoferrite. 5- calcium sulfate. 6- bismuth oxide. The later 4 phases vary among the commercial products available. Characteristics and products 1. Biocompatible with periradicular tissues 2. Non cytotoxic to cells, but antimicrobial to bacteria 3. Non-resorbable 4. Minimal leakage around the margins. 5. Very basic AKA alkaline (high pH when mixed with water). 6. As a root-end filling material MTA shows less leakage than other root-end filling materials, which means bacterial migration to the apex is diminished. 7. Treated area needs to be infection free when applying MTA, because an acidic environment will prevent MTA from setting. 8. Compressive strength develops over a period of 28 days, similar to Portland cement. Strengths of more than 50 MPa are achieved when mixed in a powder-to-liquid ratio of more than 3 to 1. Originally, MTA products required a few hours for the initial and final setting but newer materials are available that set more quickly and have added characteristics. Solid type materials for obturation of the root canal 1Semi rigid materials as silver cones which are not used now. They are flexible and fill narrow curved root canals. When silver cones contact tissue fluids or saliva, they corrode. The corrosion products are cytotoxic. 2Rigid materials as Vitalium cones which are inflexible and were used as endodontic implants.