Obturation of the Root Canal System PDF

Obturation of the Root Canal System Preclinical Endodontics – Lecture 5 Introduction The ultimate objective of the root canal therapy is the three-dimensional obturation of the endodontic space after it has been completely cleaned, shaped and disinfected. Why obturate canals? Microorganis...

Obturation of the Root Canal System Preclinical Endodontics – Lecture 5 Introduction The ultimate objective of the root canal therapy is the three-dimensional obturation of the endodontic space after it has been completely cleaned, shaped and disinfected. Why obturate canals? Microorganisms and their byproducts are the major cause of pulpal and periapical disease. However, it is difficult to consistently and totally disinfect root canal systems. Therefore, the goal of three-dimensional obturation is to provide an impermeable fluid tight seal within the entire root canal system, to prevent oral and apical microleakage. Objectives of obturation of the root canal system 1. To prevent coronal leakage of bacterial organisms, bacterial elements and nutritional elements from the oral environment to the root canal. 2. To restrain growth of any surviving bacteria in dentinal tubules and un instrumented parts of the root canal space. 3. To prevent (apical leakage) release of bacterial elements in the other direction, i.e. from the root canal to the apical environment, and to prevent leakage of nutritional elements from the periapical tissue to the canal space.  When to obturate? After the completion of root cleaning and shaping, the root canal is ready to filled when: 1. Tooth is asymptomatic. Sinus tract 2. The canal is dry. 3. There is no sinus tract. 4. There is no foul odor. 5. No swelling. 6. Temporary filling is intact.  Features of an ideal root canal obturation 1. Radiographically: Root canal free of voids, which indicate incomplete obturation. 2. Density: Uniform density of the filling material from coronal to apical. 3. Shape: Root canal filling should reflect shape of the canal, and tapered from coronal to apical. 4. Length: Filling material should reach 0.5-0.75 mm from radiographic apex.  Underfilling & Overfilling Underfill (An incomplete obturation of the root canal space due to incorrect determination of WL or inadequate cleaning & shaping of root canal system). Overfill: Obturation is too long extend beyond radiographic apex due to loss of apical stop. 10 Root canal filling materials Classification of root canal filling materials: Requirements for an ideal root canal filling material Technical: 1) No shrinkage 2) No solubility in tissue fluids, undisturbed setting in the presence of moisture. 3) Good adhesion/adaptation to dentin or combining materials (cones, sealers). 4) No pores and water absorption. 5) No tooth discoloration. Biological: 1) No general health problems or allergies for patients and dental personnel 2) No irritation of local tissues 3) Sterile 4) Antimicrobial – no enhanced bacterial growth 5) Stimulation of the periapical healing process Handling: 1) Radiopaque: ISO 6876 (76) requires >3 mm aluminum (dentin has 0.6–0.7) (radiopacity of dental materials is measured as mm aluminum equivalent). 2) Setting in an adequate time, allowing sufficient time for obturation and radiographic control 3) Easy to apply and easy to remove (e.g. for post placement) using solvents, heat or mechanical instrumentation. Root canal filling materials 1. Gutta-percha cones: Gutta-percha is derived from two words: “GETAH” meaning gum “PERTJA” name of the tree. It’s considered as most commonly used semi solid root canal filling material. It is designed to have the same size & tapering of the corresponding intracanal instrument as master cone. Typical composition of gutta-percha: 1. Zinc oxide (66%). 2. Metal sulfate (radiopacity) (11%). 3. Gutta-percha (20%). 4. Additive like colophony (rosin, mainly composed of diterpene resin), pigments or trace metals (3%). Properties of gutta-percha: Advantages Disadvantages 1. Compactible 1. Lack of rigidity 2. Tissue tolerant 2. Low adhesiveness (should be used with sealer). 3. Radiopaque 3. Shrinkage with cooling 4. Dimensionally stable 4. Distorted by pressure 5. Minimal toxicity 2. Endodontic Sealers: Root canal sealers are necessary to seal the space between the dentinal wall and the obturating core interface. Sealers also fill voids and irregularities in the root canal, lateral and accessory canals, and space between gutta-percha points used in lateral condensation. Properties of an ideal sealer: 1. Exhibits tackiness when mixed to provide good adhesion between it and the canal wall when set. 2. Establishes a hermetic seal. 3. Radiopaque, so that it can be seen on a radiograph. 4. Very fine powder, so that it can mix easily with liquid. 5. No shrinkage on setting. 6. No staining of tooth structure. 7. Bacteriostatic, or at least does not encourage bacterial growth. 8. Exhibits a slow set. 9. Insoluble in tissue fluids. 10. Tissue tolerant; that is, nonirritating to periradicular tissue. 11. Soluble in a common solvent if it is necessary to remove the root canal filling. Classification of endodontic sealers: 1. Zinc Oxide and Eugenol 2. Calcium Hydroxide Sealers 3. Noneugenol Sealers 4. Glass Ionomer Sealers 5. Resin 6. Silicone Sealers 7. Bioceramic 8. Medicated Sealers Root Canal Obturation Techniques 1. Cold lateral Compaction 2. Warm Vertical Compaction 3. Continuous Wave Compaction Technique 4. Warm Lateral Compaction 5. Thermoplastic Injection Techniques 6. Carrier-Based Gutta-Percha 7. Thermomechanical Compaction 8. Solvent Techniques 9. Pastes 10. Immediate Obturation Cold lateral condensation technique: Repeated condensation of gutta-percha and sealer against one dentinal wall using spreader creating space for insertion more accessory cones, until whole root canal is obturated. This is the most commonly used obturating technique for most of the root canal system configurations. Before obturation of the root canal, we should verify the completion of root preparation and ensure a dry and symptom less tooth. Procedures of cold lateral condensation technique: Armamentarium: 1. Gutta-percha cones. 2. Glass slab and spatula. 3. Sealer. 4. Tweezer pliers. 5.Paper points. 6. Spreaders (fingers). 7. Heat. 8. Excavator (flamed).  Steps: 1. Master apical point fitting (master cone) (tug-back). 2. Finger spreader selection. 3. Final irrigation. 4. Drying the canal(s). 5. Mixing and placement of sealer. 6. Lateral condensation procedure. 7. Searing off excess of gutta-percha. 8. Obturation radiograph. Step (1): Master apical point fitting (master cone) (tug-back) Test to determine MAP (master cone) fitting: Visual test: Make a mark at the reference point (Measure the point – Master cone has the same WL as MAF). Tactile test (tug-back): While inserting the master cone to desired position, some degree of force should be required to seat it. Once it is inside the canal, a pulling force should be required to dislodge it called as “TUGBACK”. Note: If the point is loose next larger size should be tried or Point should be cut using gutta-percha cone calibrator or scissors. If the cone does not reach the desired length: If the Cone extends beyond the apex: Radiographic test: Master cone should check radiographically to see if it coincides with working length. Step (2): Spreader selection: Finger spreader ISO coded like endodontic file & reamer with same size, length and taper. Criteria for selection suitable finger spreader for cold lateral condensation: Usually one size smaller than MAF (i.e. if master apical file is 30# so selected finger spreader should be size 25#). Rubber stops 1-2 mm short of WL. Should fit loosely in the canal. Cannot penetrate the apical constriction Step (3): Final irrigation: NaOCl or CHX. EDTA. Normal Saline Step (4): Drying the canal (s): Paper points are also color ISO coded with same size. Length and taper. It should use same size of Master Apical File (MAP). It should insert to full working length. Continue until paper point will be dry when removed from canal. Step (5): Mixing and placement of sealer: Sealer is mixed according to manufacture instruction. Thick consistency (creamy, but quite heavy). Should string out when the spatula is lifted from the mix. Small amount of sealer is placed with lentlospiral, file or coated with master gutta-percha cone. Wipe the sealer against the walls with pumping movements. Step (6): Lateral condensation procedure: 1. Coat master cone tip with sealer then insert the master cone to the WL. 2. Place spreader smaller size than MAF of (1-2) mm short to WL. Apply apical and lateral pressure. 3. Insert the accessory point into the created void corresponding with a size of the spreader has to reach the length of spreader. 4. Repeat the same procedure using smaller spreader reaching shorter to WL Stop when the spreader can no longer be pressed beyond the coronal third. Step (7): Searing off excess of gutta-percha: Sear off the excess gutta-percha at the level of CEJ or canal orifice. Use the heated excavator. Vertical condensation with a cold plugger. Clean the chamber with excess of softened gutta-percha and sealer. Restoration (Temporary or Permanent) Step (8): Obturation radiograph: Density. Length. References 1. Torabinejad M, Fouad A, Shabahang S. Endodontics e-book: Principles and practice. Elsevier Health Sciences; 2020 Jun 25. Chapter 15 (327-345) Thank you 37