Procedural Errors in Biomecanical Preparation
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This document discusses common procedural errors that can occur during root canal treatment and provides recommendations for prevention and management. The main points are: 1) Common procedural errors include canal blockage, ledge formation, deviation from normal anatomy, instrument separation, and obstruction from previous obturating materials. 2) Prevention techniques include using smaller instruments first, maintaining patency, and recapitulating. Ledges can be prevented through proper access, assessment of curvature, and avoiding forcing instruments. 3) Separated instruments may require retrieval kits or ultrasonics to remove, while previous fillings need removal through instrumentation, heat, solvents, or ultrasonics to allow retreatment.
Procedural Errors in Biomecanical Preparation
- 1. Procedural Errors in Biomechanical Preparation
- 2. Endodontic mishaps or procedural accidents are those unfortunate occurrences that happen during treatment, some owing to inattention to detail, others totally unpredictable - Dr. Mahmoud Torabinejad (1990)
- 3. Most common procedural errors during cleaning & shaping - Canal Blockage - Ledge formation - Deviation from normal canal anatomy - Instrument Separation - Obstruction by previous obturating materials
- 4. Canal Blockage • Blockage of canal is basically because of apical pushing of dentinal debris which has been removed during shaping and cleaning of the root canal.
- 5. Prevention of Canal Blockage • Always use the smaller sized instruments first. • Use the instruments in a sequential order. • Always pre-curve stainless steel hand instruments. • Use reproducible reference points and stable silicon stoppers on instruments while cleaning and shaping. • Use copious amounts of irrigants and always work in a wet canal. • Recapitulate after every step Endobender
- 6. Ledge Formation • Ledge is an artificially created deviation of the root canal wall that prevents the passage of an instrument to the apex of an otherwise patent canal CAUSES - Not extending the access cavity sufficiently to allow adequate access to the apical part of the root canal - Incorrect assessment of the root canal curvature - Erroneous root canal length determination - Forcing and driving the instrument into the canal - Using a non-curved stainless steel instrument that is too large for a curved canal - Inadequate irrigation and/or lubrication during instrumentation
- 7. Recognition • Root canal instrument can no longer be inserted into the canal to full working length. • Loss of normal tactile sensation of the tip of the instrument binding in the lumen. • Radiographically, if the instrument point appears to be directed away from the lumen of the canal
- 8. Prevention of Ledge Formation • A preoperative radiograph is taken to assess and anticipate unusual root canal curvature. • Patency of the canal should be maintained throughout the cleaning and shaping procedure. • Recapitulation with smaller instruments in between each change of instrument is the recommended method to prevent ledge formation. • Work passively without forcing the instruments into the canal. • Never force an instrument apically. If resistance exists, confirm whether there is blockage due to other causes.
- 9. Deviation from Normal Canal Anatomy Zipping Definition : Zipping is defined as the apical transportation of a curved canal caused due to improper shaping technique - When a curved foramen is filed with a small file with pressure against the outer side of the curvature, repeated filing transports and zips the canal.
- 10. Transportation • If the instrument remains within the confines of the root canal, the elliptic preparation will produce internal transportation of the foramen • If the instrument is outside the confines of the root canal, it will produce external transportation of the foramen
- 11. Elbow • Definition: Elbow is the narrowest portion of the zipped canal • A zipped canal is apical to elbow and usually obturation ends at the elbow. • It occurs as a result of the irregular widening that occurs coronally along the inner aspect and apically along the outer aspect of the curve.
- 12. Prevention is the best cure These mishaps can be prevented by • Pre-curve the initial small sized instruments • Use incremental filing technique • Use flexible files • Never rotate the instruments in curved canal NOTE : Thermoplasticized Gutta Percha technique should be used when there’s zipping or transportation of root canal.
- 13. Instrument Separation in Root Canal • Instruments separate or break only when they are used incorrectly or overused • If the instrument fractures in narrow canals or in the critical apical third of the canal, it becomes very difficult to either remove or bypass the instrument. • If the separation occurs beyond the curvature, in the apical third of the canal, or in narrow canals, then attempts to bypass the instrument should be undertaken carefully with smaller sized instruments.
- 14. Prognosis The prognosis and management of a separated instrument inside a canal are dependent upon : • Level of instrument separation in the canal (coronal, middle, or apical third) • Size of the instrument • Degree of infection beyond the level of the separation • Operator skill • Patient motivation and decision of the future course of treatment
- 15. Retrieval • There are several kits available to remove separated instruments including Endo Extractor and Mounce Extractor. • The Masserann kit works on the principle of drilling a trepan around the separated instrument to loosen it and then pick up with an Endo Extractor. • Although Endodontists prefer ultrasonic instrumentation for retrieval of separated instruments, as the ultrasonic vibrations loosen the instrument for retrieval Masermann Kit EndoExtracter ProUltra Ulstrasonic Tips
- 16. Retrieval Instrument retrieval using Masermann Kit
- 17. When to avoid retrieval ? • When an instrument is located in the apical one third there is high risk of fracture of root canal. Instead the canal should be shaped and obturated along with the broken instrument, later a root end resection should be considered • When the instrument is located in the mid-coronal portion without a straight line access, we avoid retrieval of the instrument
- 18. Obstruction from previous obturating materials • When it is required to retreat a previously endodontically treated tooth, the filling material must be removed otherwise, saving the tooth from extraction may necessitate an endodontic surgical procedure.
- 19. Removing Gutta Percha Gutta-percha and sealer can be removed by the application of: • Mechanical force in the form of instrumentation • Heat to sear and soften the gutta-percha • Solvents • Ultrasonics
- 20. Removing Gutta Percha • An excavator blade or a plastic instrument blade can be heated and seared through the exposed gutta- percha • A #20 or #25 Hedstrom file can be mechanically inserted into the canal orifices or a Gates-Glidden drills can be used for the same purpose Hartzell GP Excavator
- 21. Removing Gutta Percha • Organic solvents like Chloroform or Trichloromethane can be used to effectively dissolve gutta percha from the orifice and mid-root canal. • Chloroform has cytotoxic effects and is a group 2B carcinogen as recognised by the International Agency for research on cancer. • Hence alternatives to this solvent are being considered and researched upon, like rectified Terpentine oil, Orange Solvent or D-limonene
- 22. Removing Gutta Percha • Thermostatically heated pluggers can also be employed while ultrasonic tips are an alternative method to the thermostatically controlled heated pluggers Thermostatic Heated plugger tip ProUltra Zirconium Nitride Tips
- 23. Removing Silver Points • A silver cone is not removed as easily as a gutta percha cone unless the butt end of the silver cone extends into the pulp chamber. • The butt end of the silver cone is vibrated with an ultrasonic scaler to break the cementing media. • The cone is then grasped with a pair of narrow-beaked Stieglitz pliers and is removed.
- 24. Thanks for your patience !