Canal preparation for RCT

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cleaning and shaping

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Canal preparation for RCT

  1. 1. Objectives of Canal Preparation Start with the end in mind
  2. 2. 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
  3. 3. Objectives of root canal preparation The canal is • Cleansed primarily by irrigation • Shaped primarily by instrumentation
  4. 4. Five Mechanical objectives •Develop a continuously tapering conical form in the root canal preparation •Make the canal narrower apically, with the narrowest cross-sectional diameter at its terminus •Make the preparation in multiple planes •Never transport the foramen. •Keep the apical foramen as small as possible Herbert Schilder The real key to obturation is Cleaning and Shaping
  5. 5. Cleansing of the root canal Objectives • Removal of organic and inorganic debris • Elimination of bacteria
  6. 6. Instruments Instruments differ according to: • Metal • Tip design • Cross sectional geometry • Length of cutting blades • Sizing • Taper
  7. 7. Metals Nickel titanium Stainless steel Excellent flexibility Less flexible Conforms to canal Straightens and curvature transports canal No deformation Permanent deformation
  8. 8. ISO-Symbols = K-Reamer = K-File = H-File = Rat Tail File = Nervbroach = Paste Filler
  9. 9. METHODS OF DETERMINING WORKING LENGTH • Radiographic Methods • Digital Tactile Sense • Apical Periodontal Sensitivity • Paper Point Measurement • Electronics
  10. 10. Clinical Technique Actual WL determination • Radiograph • Apex locator
  11. 11. Clinical Procedure Apex Locator
  12. 12. Clinical Procedure Actual WL determination Preparation should terminate at • Apical constriction • 1 mm short of radiographic apex
  13. 13. Clinical Procedure • Estimate working length • Parallel radiograph • Estimated working length is the distance from the reference point to the radiographic apex
  14. 14. • Apico coronal techniques( standardized ,step-back, balanced force ) • Corono-apical techniques ( step-down , Double flared, crown-down- pressureless) Root canal preparation
  15. 15. • Standard technique • Step-back technique • Serial shaping technique • Anti-curvature filing • Balance force preparation • Crown down technique
  16. 16. Instrumentation • Motion of instrumentation: Filing and Reaming • Combination with reaming and filing: 1. Turn-and-Pull 2. Watch-Winding 3. Watch-Winding-and-Pull • Anti-curvature filing
  17. 17. Step-back technique
  18. 18. Step-back technique
  19. 19. Master Apical File • Take a radiograph with MAF in place. This confirms: – Length – Placement
  20. 20. RECAPITULATION Repeated reintroduction and reapplication of instruments previously used throughout the cleaning and shaping process in order to create well-designed, smooth, unclogged, evenly tapered root canal preparations.
  21. 21. Apical Patency Maintain a pathway through the apical constriction with a small K-file (#10 or #15) during cleaning and shaping
  22. 22. Other methods ;
  23. 23. Crown Down Technique •Coronal third Orifice shapers •Middle third 0.06 taper rotary Profiles •Apical third 0.04 taper hand Profiles
  24. 24. Crown Down Technique • The coronal portion is prepared before the apical portion • Reduces effect of canal curvature • Improves tactile awareness during apical preparation • Allows more effective irrigation • Removes majority of tissue and microbes before apical third is approached • Reduces change in working length during apical preparation
  25. 25. Anti-curvature filing
  26. 26. Irrigation An ideal irrigant: • Is nontoxic • Dissolves vital and necrotic tissue • Is bactericidal • Lubricates the canal
  27. 27. • Sodium Hypochlorite: • Lower concentrations (e.g., 0.5% or1%) dissolve mainly necrotic tissue • Chlorhexidine: • A broad-spectrum antimicrobial agent effective against gram- negative and gram-positive bacteria • A cationic molecular • binds to hydroxyapatite Iodine Potassium Iodide: • an oxidizing agent by reacting with free sulfhydryl groups of bacterial enzymes • MTAD • EDTA • Hydrogen peroxide
  28. 28. Cleaning---Irrigation • Sodium Hypochlorite? • Dissolves organic debris ✔ • Has a powerful anti-bacterial action ✔ • Lubricates the use of files ✔ • Disinfects & cleans where files don’t reach ✔ • The tissue-dissolving ability of 5.25-1% What irrigant should we use?
  29. 29. Sodium hypochlorite • Dissolves vital and necrotic tissue • Is bactericidal • Lubricates the canal
  30. 30. Smear layer • What is the smear layer ? • Remove ?
  31. 31. Prolube • Facilitates placement of file • Entraps debris • Aids in removal of the smear layer EDTA and carbamide peroxide in a water soluble base
  32. 32. Good luck

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