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Cleaning and Shaping of the Root Canal System

Cleaning and Shaping of the Root Canal System. Edit by Hou Tiezhou 02988088507. Objectives of Canal Preparation. Start with the end in mind. Objectives of root canal preparation. The root canal system must be: Cleaned of its organic remnants

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Cleaning and Shaping of the Root Canal System

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  1. Cleaning and Shaping of the Root Canal System Edit by Hou Tiezhou 02988088507

  2. Objectives of Canal Preparation Start with the end in mind

  3. Objectives of root canal preparation The root canal system must be: • Cleaned of its organic remnants • Shaped to receive a three dimensional filling of the entire root canal space

  4. Objectives of root canal preparation The canal is • Cleansed primarily by irrigation • Shaped primarily by instrumentation

  5. Hence cleansing and shaping

  6. Cleansing of the root canal Objectives • Removal of organic debris • Elimination of bacteria

  7. Irrigation An ideal irrigant: • Is nontoxic • Dissolves vital and necrotic tissue • Is bactericidal • Lubricates the canal • Removes the smear layer

  8. Sodium hypochlorite • Dissolves vital and necrotic tissue • Is bactericidal • Lubricates the canal

  9. Sodium Hypochlorite Cannot be considered non-toxic!!!

  10. Prolube EDTA and carbamide peroxide in a water soluble base

  11. Prolube • Facilitates placement of file • Entraps debris • Aids in removal of the smear layer

  12. EDTA • Chelating agent • Effectively removes smear layer

  13. Shaping of the root canal • Canal shape – produced by instrumentation • Objective is a smooth tapered preparation

  14. Shaping of the root canal

  15. Instruments Instruments differ according to: • Metal • Taper • Tip design • Cross sectional geometry • Length of cutting blades • Sizing

  16. Nickel titanium Stainless steel Excellen flexibility Less flexible Conforms to canal Straightens and curvature transports canal Plastic deformation Permanent deformation Metals

  17. Metals Stainless steel files demonstrate permanent deformation

  18. Metals Nickel titanium files demonstrate plastic deformation

  19. Taper Definition Increase in diameter per unit length

  20. 0.32 mm diameter increase D16 D1 What is Taper? D16 D1 0.96 mm diameter increase

  21. What is taper?

  22. Taper Taper of instruments in U of M file kit • Stainless steel files – 0.02 taper • OS – variable tapers ranging from 0.05 to 0.08 • Series 29 rotary Profiles – 0.06 taper • NiTi hand files – 0.04 taper

  23. Tip Design • Non-cutting tip • Bullet nose (60 degree) tip • Smooth transition angle where tip meets flat radial lands

  24. Tip Design • Designed to follow a pilot hole • Guides instrument through canal during preparation

  25. Tip Design

  26. Cross-sectional geometry • Three radial lands • Each contains bidirectional cutting edges • Keep instrument centered in the canal • Cutting edges scrape dentin

  27. Cross sectional geometry

  28. Cross sectional geometry

  29. Cross sectional geometry • Radial lands separated by three u-shaped flutes • Provide space for accumulation of debris • Moves debris out of canal

  30. Length of cutting blade • Traditionally 16 mm • Orifice shapers – 10 mm

  31. Sizing of instruments ISO sizes • Number refers to tip diameter in tenths of mm • The tip diameter increases by 0.05 mm from sizes 10 to 60, then by 0.10 mm

  32. Sizing of instruments • % increase in diameter from #10 to #15 file is 50% • Difference between #55 and #60 is only 9%

  33. Sizing of instruments Series 29 • Progressive 29% increase in tip diameter • Instruments are better spaced • More instruments in smaller sizes and fewer large instruments

  34. Crown Down Technique • The coronal portion is prepared before the apical portion • Follows medical principle of cleansing before probing a wound

  35. Crown Down Technique

  36. Crown Down Technique • Eliminates constrictions in the coronal region • Reduces effect of canal curvature • Improves tactile awareness during apical preparation

  37. Crown Down Technique • Allows more effective irrigation • Removes majority of tissue and microbes before apical third is approached • Reduces change in working length during apical preparation

  38. Crown Down Technique • Coronal third Orifice shapers • Middle third 0.06 taper rotary Profiles • Apical third 0.04 taper hand Profiles

  39. Clinical Procedure • Estimate working length • Parallel radiograph • Estimated working length is the distance from the reference point to the radiographic apex

  40. Parallel Radiograph

  41. Clinical Procedure • Establish straight line access to apical third

  42. Clinical Procedure Explore canal patency • Ensure that canal is negotiable to radiographic apex • Small file – #10 K-file • May need to precurve these SS files

  43. Clinical Procedure • Files used in a push/pull or quarter turn pull motion • Never rotate these files through 360 degrees

  44. Clinical Procedure

  45. Clinical Procedure

  46. Clinical Procedure Estimate canal size • Radiographic appearance • Crown/root morphology • Standardized tables

  47. Estimation of canal size

  48. Estimation of canal size See Table in manual

  49. Clinical Procedure Actual WL determination Preparation should terminate at • Apical constriction • 1 mm short of radiographic apex

  50. Clinical Technique Actual WL determination • Radiograph • Apex locator

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