Cleaning and shaping of the root canal system has both mechanical and biological objectives. It aims to create a continuously tapered shape from the coronal to apical ends while maintaining the natural curvature and apical foramen. Proper cleaning and shaping requires adequate access preparation, working length determination, irrigation, and the use of step-back or crown-down techniques. Potential errors include ledge formation, perforation, canal blockage, and separated instruments.

1. Cleaning & ShapingDr. Ashraf RefaiBDS MSc DD HMDLecturer of EndodonticsAl-Azhar University / MIUwww.arefai.edublogs.org

2. Why Should We Clean & Shape?Any Ideas???

3. Objectives of Cleaning & Shaping

4. Mechanical ObjectivesCreate a continuous taper with the narrowest part apically and the widest part coronal.Preserve the natural curvature of the canalPreservation of the apical foramenCreation of an apical stop (seat)Objectives of Cleaning & Shaping

5. Biological ObjectivesTotal removal of organic and inorganic debris in root canal systemDisinfection of the root canal systemDo no harm the tooth or the periodontiumObjectives of Cleaning & Shaping

6. Outline FormResistance FormRetention FormExtension For preventionToilet of Cavity (Irrigation)Principles of Radicular Cavity Preparation

7. Canals are wider in one dimension and not the otherThe cross-section of the canal is rarely roundedThere are high percentages of extra canalsLateral & Accessory canals do existsAll canals have a degree of curvatureComplex Anatomy that Should be Considered

8. The Myth of the GeometricallyTapered & Straight Canal

9. Preparation for Root CanalEnlargement

10. Proper coronal cavity preparationTooth Length DeterminationApical Constriction(o.5 to 1mm) Minor Diameter Major DiameterPreparation for Root Canal Enlargement

11. Radiographic Method (Ingle’s Method)Tentative lengthReduction of estimated lengthPlacement of the instrument in the canalExposure of a radiographAdjustment of the lengthRetake the radiograph (If necessary)Methods of Tooth Length Determination(Preparation for Root Canal Enlargement)

12. The Radiographic Method

13. The SLOB RULESLOBBuccalOppositeLingualSame

14. Apex LocatorsUsed in combination with the radiographic techniquesMethods of Tooth Length Determination(Preparation for Root Canal Enlargement)

15. How Does it Work???

16. Different Apex Locators

17. Pulp extirpation & tissue debridementIrrigation (Chemical)The rule isAs much as you canAs many times as you canPreparation for Root Canal Enlargement

18. Functions of an IrrigantTo physically flush debrisTissue solventAntibacterial agentLubricantIrrigation (Preparation for Root Canal Enlargement)

19. Irrigation (Preparation for Root Canal Enlargement)

20. Types of IrrigantsSodium Hypochlorite (NaOCl)Preferred irrigantUsed in full concentration or half concentration 5.25% or 2.625%Excellent tissue solventCan be combined with H2O2Best results alternating with EDTAIrrigation (Preparation for Root Canal Enlargement)

21. Types of IrrigantsEthylene Diaminetetracetice Acid (EDTA)Strong chelating agentStrong antibacterial agentNot a tissue solventTypes: RC prep & GlydeAvailable in gel formIrrigation (Preparation for Root Canal Enlargement)

22. Types of IrrigantsHydrogen Peroxide 3% (H2O2)Nascent oxygen (Antibacterial)Effervescence or Bubbling actionIrrigation (Preparation for Root Canal Enlargement)

23. Types of IrrigantsChlorohexidineGluconate 0.2%Comparable to NaOCl but without tissue solvent capabilityQuaternary Ammonium CompoundsAntiseptic, not a tissue solvent, low toxicityIrrigation (Preparation for Root Canal Enlargement)

24. Preparation for Root Canal EnlargementMethodOfIrrigation

25. Steps of Root Canal Enlargement

26. Root Canal Enlargement(Hand Instruments)

27. Root Canal Enlargement(Instrument Motions)Push & PullReaming Turn & PullWatchWindingBalancedForce

28. Root Canal Enlargement(Techniques: Direction & Sequence)Step Back Technique

29. Why do we clean & shape?Mechanical ObjectivesBiological ObjectivesThe Myth of the Geometric CanalPreparation for root canal enlargementProper accessTooth length determinationIrrigation Functions of an irrigantIdeal properties of an irrigantTypes of irrigantsComponents of a preparation techniqueStep-Back TechniqueMid Lecture Revision

30. Root Canal Enlargement(Techniques: Direction & Sequence)Crown Down Technique

31. Root Canal Enlargement(Engine Driven Instruments)Rotary instruments had a tendency:

32. For canal packing with dentin debris

33. For ledges and perforations

34. For canal straightening

35. For instrument breakage

36. For loss of operator tactile senseHistorically they were not widely accepted

37. Root Canal Enlargement(Engine Driven Instruments)With the introduction of NiTi instruments attitudes changed

38. Root Canal Enlargement(Engine Driven Instruments)Vibratory instrumentsHow were they used?

39. Considerations when Preparing Curved CanalsBe aware of the curves in the canal

40. Always use an Irrigant

41. Never skip files

42. Never force files

43. Precurve your files

44. Anticurvature filing

45. Use hybrid techniques (Enlarge coronally first)

46. Use NiTi FilesConsiderations when Preparing Curved Canals

47. When Should You End Your Preparation?When the walls feel smooth and the dentin chips appear yellow white

48. When there is sufficient resistance form (3 sizes above the initial file)

49. Adequate taper (To accommodate for a spreader 1-2 to the apex)Procedural Errors During Cleaning & Shaping

50. Procedural Errors During Cleaning & Shaping

51. When Should You End Your Preparation?When the walls feel smooth and the dentin chips appear yellow white