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Biomechanical instrumentation

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Biomechanical instrumentation lecture

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Biomechanical instrumentation

  1. 1. Rotary Canal Preparation Dr. Ebtissam Al-Madi Al-Madi, 491 Den 1
  2. 2. Outline • Objectives of Cleaning & Shaping – Biological – Clinical – Mechanical • Instrumentation Techniques – Stepback technique – Crowndown technique – Rotary Instrumentation Al-Madi, 491 Den 2
  3. 3. • Biological Objectives – Removal of all tissue, bacteria and bacterial products and substrates from the root canal system • Mechanical – Shaping of the root canal system to facilitate placement of a root canal filling • Clinical – Eliminate apical periodontitis and return tooth to normal function Al-Madi, 491 Den 3
  4. 4. Cleaning Endodontic Triad Shaping Filling Shaping to facilitate cleaning and Filling Al-Madi, 491 Den 4
  5. 5. Restoration Obturation Cleaning & Shaping of the canal Access Preparation Al-Madi, 491 Den 5
  6. 6. Stepback Al-Madi, 491 Den 6
  7. 7. Stepback Technique (1960’s) • The most widely used preparation technique • Replaced Non-tapering Preparation technique Al-Madi, 491 Den 7
  8. 8. Stepback Technique • Apical Preparation: 1. Establish access (straight line) 2. Establish working length 3. File Instrument (watch-winding, file, ream, etc) 4. Place next larger file, instrument, and repeat till you reach file 3-4 sizes larger (MAF) Al-Madi, 491 Den 8
  9. 9. Stepback Technique • Step back: 1. Place next larger file to a length 1 mm shorter of working length, file, irrigate and recapitulate 2. Repeat process with successively larger files at 1 mm increments shorter than preceding file. Al-Madi, 491 Den 9
  10. 10. Stepback Technique • Variations to the classic stepback technique – Initially enlarge coronal aspect with GG burs – Complete coronal preparation with GG burs – Use of small GG burs in mid-root level – Use of Hedstrom files to flare the preparation Al-Madi, 491 Den 10
  11. 11. Stepback technique • Advantages – Minimize procedural errors (transportation, ledging, apical perforation) • Disadvantages – Significant apical extrusion of debris (post-operative pain) – Apical blockage – Canal deviation – Alteration of working length Al-Madi, 491 Den 11
  12. 12. Crown down Al-Madi, 491 Den 12
  13. 13. Crowndown Technique • More recent technique • Produce similar result to step-back Al-Madi, 491 Den 13
  14. 14. Crowndown technique • Development of straight-line access • Eliminate pulp chamber obstructions and check patency • GG enlargement with size 4-3-2, irrigate • Coronal to mid root enlargement with instruments from large to small, irrigate • Establish working length, irrigate • Introduce progressively smaller files deeper into the canal until resistance is encountered • Establish apical preparation size • Complete preparation Al-Madi, 491 Den 14
  15. 15. Crowndown technique • Variations to the classic crowndown technique – Crown-down pressure-less technique – Roane technique – Double flare technique – Modified double flare technique – Rotary Instrumentation Al-Madi, 491 Den 15
  16. 16. Crowndown technique • Advantages – Reduce apical extrusion (reduce pain) – Elimination coronal interferences – Improved irrigation to apical part of canal – Facilitate working length determination • Disadvantages – Early blockage of canal Al-Madi, 491 Den 16
  17. 17. Instruments Hand Instruments Rotary Instruments Al-Madi, 491 Den 17
  18. 18. Hand instruments • Been in use for over 100 years • Still integral part of cleaning & shaping • Better tactile sensation • ISO standardization • Broaches, k-files, Flex- R files, NiTi files, H-files Al-Madi, 491 Den 18
  19. 19. Hand engine driven • Properties of NiTi Alloy – Superelasticity – High resistance to cyclic fatigue • Series 29 Al-Madi, 491 Den 19
  20. 20. Rotary Files • Advantages – Less transportation and ledging – Shape canal uniformly – Reduced operator fatigue – Improved efficiency • Disadvantages – Cannot be used in some cases – Buildup of debris – Cannot use beyond apical foramen – Fracture can occur suddenly – Initial cost – Loss of tactile sensation Al-Madi, 491 Den 20
  21. 21. Rotary Instruments • Lightspeed • Profile • Hero • Quantec • K3 • Flexmaster • GT • Protaper • Sequence • RaCe • V-taper Al-Madi, 491 Den 21
  22. 22. Design characteristics • Non-cutting vs cutting tip • Tip size • Taper • Cross section • Rake angle • Helix angle • Pitch Al-Madi, 491 Den 22
  23. 23. • Tip could be non-cutting, cutting Tip shape Al-Madi, 491 Den 23
  24. 24. Tip Size • Can be the same as ISO hand tips sizes- color coded accordingly • Can be half sizes (12.5, 17.5, etc) as in Light Speed. • Can skip sizes ( only 20,30, 40) as in GT rotary • Can be nonspecific sizes (according to percentages ex. 18.5, 20..) as in ProTaper. Al-Madi, 491 Den 24
  25. 25. Tip Taper Taper ranges from 0.02 to 0.12 Al-Madi, 491 Den 25
  26. 26. • Constant taper- Variable tip – Hand files (0.02) – Profile 0.04 • Graduating taper- constant tip size – GT series – Quantec • Varying taper- different tip sizes – ProTaper Tip Taper Al-Madi, 491 Den 26
  27. 27. Cross section- Radial Lands A radial land is a surface that projects axially from the central axis, between flutes, as far as the cutting edge Non-cutting tips and radial lands keeps a file centered in the canal. Al-Madi, 491 Den 27
  28. 28. Cross section- Radial Lands Smaller radial land equals decreased strength for blade support Increased radial land increases peripheral strength behind the cutting blade Al-Madi, 491 Den 28
  29. 29. Rake Angle The rake angle is the angle formed by the cutting edge and a cross section taken perpendicular to the long axis of the instrument Rake angles affect the cutting efficiency and the aggressiveness of the file Al-Madi, 491 Den 29
  30. 30. Overly Positive Rake Angle Positive Rake Angle Neutral Rake Angle Negative Rake Angle Rake Angle Al-Madi, 491 Den 30
  31. 31. • As the flute angle is increased more debris can be carried away from canal. Helical flute angles The helical angle is the angle that the cutting edge makes with the long axis of the file • Constant helical flute angles allow debris to accumulate and are more susceptible to the effect of “screwing in” forces. Al-Madi, 491 Den 31
  32. 32. Al-Madi, 491 Den 32
  33. 33. Al-Madi, 491 Den 33
  34. 34. Pitch Pitch is the number of spirals or threads per unit length. Constant pitch and constant helical angles produce a “pulling” or “sucking down into” the canal. Al-Madi, 491 Den 34
  35. 35. Al-Madi, 491 Den 35
  36. 36. Lightspeed (Senia & Wildey 1990’s) • Long, thin non-cutting shaft • U shape design • Most flexible RI • Low incidence of transportation, preparation errors, and loss of working length Al-Madi, 491 Den 36
  37. 37. Profile (Ben Johnson 1994) • Increased taper • Began as series 29 #0.02 taper, then #0.04 and 0.06 tapers • Profile (maillefer- Europe) manufactured tips similar to ISO • Negative rake angle Al-Madi, 491 Den 39
  38. 38. • Coronally pre-enlarge • Use of Orifice shapers • Alternative use of #.04 and #.06 tapers as well as alternate tip sizes • Same basic technique for similarly designed files Al-Madi, 491 Den 40
  39. 39. Profile Al-Madi, 491 Den 41
  40. 40. Profile Al-Madi, 491 Den 42
  41. 41. K3 (McSpadden) • Predecessors: Quantec • Unique cross sectional design with +ve rake angle, 3 wide radial lands, peripheral blade relief Al-Madi, 491 Den 47
  42. 42. ProTaper (Cliff Ruddle, John West, Pierre Matchou) • Only 6 instruments • Modified k file with no radial lands • Varying taper that increase coronally in shaping files and opposite in finishing files Al-Madi, 491 Den 50
  43. 43. ProTaper Al-Madi, 491 Den 52
  44. 44. Hybrid technique • Instruments can be used in a manner that promotes their individual strengths and avoids their weaknesses • Hand instruments secure a patent glide path • Tapered rotary instruments efficiently enlarge coronal canal areas • Less tapered instruments allow additional apical enlargement Al-Madi, 491 Den 56
  45. 45. Newer Rotary Instruments? • Light Speed • Hero 642 • GT files • Quantec • Flexmaster • RaCe • V-Taper • Endo Sequence Al-Madi, 491 Den 57
  46. 46. More information • Pathways of the Pulp 9th e-edition • Endodontics- Ingle 5th CD editon • Advanced Endodontics- Rhodes • Endodontics- Stock • JOE • IEJ • Company brochures & Videos • Internet Al-Madi, 491 Den 58
  47. 47. How & Where to learn? • Read & understand the brochure- Don't be fooled! • Read the literature in textbooks and journals- Be an informed consumer. • Try on extracted teeth till you master the technique- try before you buy. Al-Madi, 491 Den 59

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