Endodontic Materials PDF

**Endodontic Materials** **Introduction** - **Purpose of Endodontic Materials**: Used to obturate (fill) the root canal system when pulp tissue is destroyed due to: - Trauma - Tooth decay involving pulp infection **Objectives of Endodontics** 1. **Cleaning and Shaping**:...

**Endodontic Materials** **Introduction** - **Purpose of Endodontic Materials**: Used to obturate (fill) the root canal system when pulp tissue is destroyed due to: - Trauma - Tooth decay involving pulp infection **Objectives of Endodontics** 1. **Cleaning and Shaping**: - Prepare the root canal to within 0.5 mm of the maximum constriction near the periapex. 2. **Obturating the Canal**: - Use a combination of materials for a complete three-dimensional filling. - Materials must be inert and biocompatible. 3. **Sealing**: - Ensure an adequate seal at the coronal extent to prevent bacterial reinfection from the oral cavity. **Types of Materials Used** - **Irrigants and Lubricants**: Used during canal preparation. - **Interim Materials**: Maintains disinfection between clinical visits. - **Bulk Fill Material and Sealant**: Used for canal obturation. - **Restorative Materials**: Seals the canal access (discussed elsewhere). - **Surgical Materials**: Used in endodontic surgery and for internal repairs within the root canal system. **Endodontic Irrigants and Lubricants** **Purpose of Endodontic Irrigants** - **Flush Debris**: Remove debris from root canal preparation. - **Disinfection**: Help disinfect the canal. **Properties of an Ideal Irrigant (Walton & Torabinejad, 2002)** - **Dissolve/Disrupt Tissue**: Effective in breaking down tissue and debris. - **Non-Toxic**: Safe for use in the canal. - **Low Surface Tension**: Allows penetration into inaccessible areas. - **Lubrication**: Helps lubricate instruments within the canal. - **Sterilization/Disinfection**: Should sterilize or at least disinfect the canal system. - **Remove Smear Layer**: Effectively removes debris from canal walls. **Commonly Used Irrigants** - **Sodium Hypochlorite**: - Most effective irrigant available. - Typically used at concentrations of 2-10%. - Can be diluted from commercially available "thin bleach" (5.25% hypochlorite) by mixing 1:1 with water to create a 2.6% solution. - **Disadvantages**: - Tissue irritant, causing ulceration if ingested or extreme inflammation if extruded into surrounding bone. - Isolation with a rubber dam is recommended to prevent oral leakage. - **Chlorhexidine Gluconate** - **Concentration**: 0.2% solution. - **Alternative**: Recommended when sodium hypochlorite usage is unsafe. **Additional Lubricants** - **EDTA (Ethylene Diamine Tetra Acetic Acid)** - **Form**: Gel preparations used as custom lubricants. - **Function**: Softens canal walls and aids in negotiating mineralized canals. **Intra-canal Medicaments** **Overview** - **Controversial Use**: The benefits of intra-canal medicaments are debated, with limited evidence supporting their use unless there are specific issues like: - Difficulty in obtaining pulpal anesthesia. - Inducing root apex formation in young patients. - Arresting internal or external root resorption. **Common Intra-canal Medicaments** 1. **Paramonochlorophenol (PMCP)** - **Purpose**: Used as a disinfectant to reduce the risk of recurrent infection. - **Limitations**: - Effectiveness is short-lived due to denaturation in the presence of calcium. - Currently lacks clinical indications for routine use. 2. **Non-setting Calcium Hydroxide Paste** - **Properties**: - High pH (around 11) with potent antimicrobial action. - Mild tissue irritant. - **Uses**: - Promotes root apex closure (apexogenesis) in non-vital teeth. - Can be retained in the tooth for extended periods to facilitate apex closure or to manage root resorption. - **Rationale**: Routine use between visits is unclear. 3. **Poly-antimicrobial Paste** - **Composition**: Proprietary mixture of corticosteroid, sulphonamide, and tetracycline. - **Application**: Used for managing inflamed pulp (hot pulps) where local anesthesia is less effective due to altered tissue pH. - **Effectiveness**: Reduces pulpal inflammation, aiding access at subsequent visits. - **Duration**: Loses effectiveness after 5 to 7 days, so should not be left longer in the pulp chamber. **Endodontic Obturation Materials** **Root canal anatomy**: A complex, 3D space that needs to be cleaned, shaped, and prepared for obturation. **Contemporary canal preparation**: ○ Focuses on removing bacteria and debris, not on creating a specific geometric shape. ○ Materials used need to be **plastic during placement** to mold to the canal\'s shape. ○ Must allow easy removal for potential future treatments like post-placement or re-treatment. **Historical Materials in Endodontics** **Silver Points** - **Usage**: Silver points were historically used to obturate root canals, designed to match the taper of the files or reamers used for canal preparation. - **Technique**: - Aiming to create a smooth, tapered canal wall for the silver points to fit securely. - Points were sealed with a suitable sealant. - **Flaws**: - Root canal anatomy is often too complex for effective sealing through machining. - Silver points are prone to corrosive breakdown within the canal, compromising the seal. - **Variants**: - Silver points could fill the entire canal length or be intentionally weakened, leaving a 5--6 mm segment at the apex for potential post preparation. - **Challenges**: - Difficulty retrieving apical fragments if the procedure failed, complicating retreatment efforts. **Dental Amalgam** - **Usage**: Conventional dental amalgam was used as a root filling material with specialized carriers and pluggers for delivery and condensation at the apex. - **Limitations**: - The mercury-rich layer could not be removed from the filling surface, raising concerns about safety. - Like silver points, this method was not suitable for retreatment and presented technical challenges. - **Sealants in Endodontics** - **Purpose of Sealants** - **Function**: Sealants fill spaces between increments of bulk fill material and improve adaptation to root canal walls, maintaining the seal around root fillings. - **Ideal Properties of Sealants (Grossman et al.)** - **Tissue Tolerance**: Safe for surrounding tissues. - **Insolubility**: Should not dissolve in tissue fluids. - **Dimensional Stability**: Maintain shape during setting. - **Hermetic Sealing**: Provide an airtight seal. - **Radiopacity**: Visible on radiographs. - **Bacteriostatic/Bacteriocidal**: Inhibit or kill bacteria. - **Good Adhesion**: Bond well to canal walls when set. - **Ease of Mixing**: Simple to prepare. - **Non-staining**: Should not discolor surrounding tissue. - **Slow Setting Time**: Extended time for precise application. - **Easily Removable**: Should be soluble for easy removal if necessary. - **Types of Sealants** - **Form**: Typically thin pastes that can coat bulk fill materials and be introduced into the canal. - **Common Sealants** - **Glass Ionomer** - Good seal to tooth structure but sets too rapidly for clinical use. - **Zinc Oxide and Eugenol** - Widely used, exemplified by Grossman's formulation: - **Characteristics**: Long setting time (up to 2 months), good peripheral seal, retrievable filling. - **Calcium Hydroxide-Based Products** - Provide a good short-term seal but may have long-term solubility issues. - **Epoxy Resin-Based Sealant** - **Benefits**: Good seal, antimicrobial action. - **Drawbacks**: Associated with dentine staining because it contain 10% silver and formaldehyde release which is tissue toxic. - **Resin and Dentine Bonding Agents** - Used with polyester bulk fill materials. - **Mechanism**: Chemically setting composite resin luting agents bonded to both root dentine and bulk fill material. **Bulk Filling Materials in Endodontics** **Purpose** - **Function**: Bulk filling materials are used to fill the large defects in prepared root canals, providing an inert mass that is malleable during insertion and dimensionally stable after placement. **Commonly Used Materials** 1. **Gutta Percha** - **Description**: The most widely used bulk filling material. - **Source**: Derived from latex as trans-polyisoprene. - **Forms**: - **α Form**: Natural state, used in thermoplastic techniques. - **β Form**: Produced by slow cooling of α material, used in cold packing techniques. - **Composition**: - Trans-polyisoprene , zinc oxide , additional components: coloring agents, resins, waxes, antioxidants, and metallic salts for improved radiographic visibility. - **Presentation**: Available as tapered cones (matched or unmatched to instruments) or as pellets for use in gun-type delivery systems. 2. **Polyester Resin** - **Example**: Resilon®. - **Composition**: Thermoplastic synthetic polyester, barium sulfate, bismuth chlorate, and bioactive glass. - **Bioactive Properties**: Claims to release calcium and phosphate ions upon exposure to bodily fluids, potentially stimulating bone growth. - **Forms**: Available in both tapered and pelleted forms, suitable for cold or thermoplastic filling techniques. **Materials for Root Canal Repair and Peri-radicular Surgery** **Overview** A variety of materials have historically been used for root canal repair and peri-radicular surgery, including: - Dental amalgam - Zinc oxide and modified zinc oxide pastes - Glass ionomer cements **Ideal Material: Mineral Trioxide Aggregate (MTA)** - **Composition**: - Tricalcium silicate - Dicalcium silicate - Tricalcium aluminate - Tetracalcium alumino-ferrite - Calcium sulfate - Bismuth oxide (increases radiopacity and modifies setting reaction) - **Properties**: - Chemically similar to Portland cement, with the addition of bismuth oxide. - Strongly alkaline and sets upon exposure to water. - **Setting Reaction**: - **Initial Phase**: Hydration of particle surfaces, partial dissolution of calcium sulfate. - **Crystal (ettringite) Formation**: Formation of hydrated calcium aluminum sulfate hydroxide (ettringite) from tricalcium aluminate interaction. - **Plastic/Delay Phase**: Material remains workable, allowing for insertion into defects. - **Final Setting**: Growth of calcium silicate hydrate crystals and ettringite, forming a rigid mass. - **Moisture Requirement**: Continues to require moisture for complete setting and can take several hours to reach maturity. - **Expansion**: MTA exhibits significant expansion during setting, which can improve sealing but may risk root fracture if excessive. **Biocompatibility and Applications** - **Biocompatibility**: Evidence suggests it can induce cementogenesis, making it useful in apexification procedures for immature teeth. - **Sealing Ability**: Provides a good seal at the root-material interface. - **Antimicrobial Properties**: Its alkalinity contributes to its antimicrobial effects.