Dentine caries _cons_1_._

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Dentine caries _cons_1_._

  1. 1. DENTINE CARIES ITS PROGRESSION AND HOW BEST TO STOP IT
  2. 2. Dental Caries Sugar and plaque, the arch criminals of dental caries
  3. 3. Dental Caries Demineralization, remineralization Sugar + Dental Plaque ACID S Demineralization Cavities
  4. 4. Dental Caries Demineralization, remineralization Subsurface demineralization of enamel
  5. 5. Dental Caries Demineralization, remineralization Occlusal lesions can be arrested by remineralization
  6. 6. Dental Caries Demineralization, remineralization recently cleaned front teeth with signs of demineralization and gingivitis after some weeks remineralization has taken place and the gingivitis is healed
  7. 7. Dental Caries Demineralization, remineralization No sugar before sleeping
  8. 8. Dental Caries The Caries Balance Resistance  Plaque removal  Sugar reduction  Fluoride  Sealants  Chlorhexidine
  9. 9. Dental Caries Structure of dentine      Living tissue Peritubular dentine Intertubular dentine Apatite crystals Intermolecular cross-linking
  10. 10. Dental Caries Dentine Structure
  11. 11. Dental Caries Progression of dentine caries Bacterial Invasion 1 2 3 4 5 6 7 8
  12. 12. Dental Caries Progression of dentine caries  Bacterial Invasion 1 2 3  Bacteria need to have a source of nutrients, i.e. from the oral environment.  Bacteria are found mostly in the biomass with few being found in the dentine tubules. 4 5 6 7 8
  13. 13. Dental Caries Progression of dentine caries Crystal Removal Process 1 2 3 4 5 6 7 8
  14. 14. Dental Caries Progression of dentine caries Crystal Removal Process 1  2 3 4 5 6 7 8   Acid from fermentation process penetrates the dentine tubules ahead of bacterial invasion. This softens the dentine matrix. The collagen fibres are reversibly damaged in the dissolution process. cont’d
  15. 15. Dental Caries Progression of dentine caries Crystal Removal Process (cont’d) 1  2 3 4 5 6 7 8  Continuation of acid production dissolves crystals in the peritubular and intertubular dentine. Further continuation of acid production breaks the intermolecular crosslinks of collagen fibres irreversibly.
  16. 16. Dental Caries Progression of dentine caries Defense reaction in dentine 1 2 3 4 5 6 7 8
  17. 17. Dental Caries Progression of dentine caries  1 2 3 4 5 6 7 8 Defense reaction in dentine A defence reaction takes place in the dentine.  Dissolution alters the hydroxyapatite crystals.  Crystals with a lower hardness and a lower calcium density (= whitelockite) remain.  The dentine tubules are blocked by precipitated intratubular whitelockite crystals. cont’d
  18. 18. Dental Caries Progression of dentine caries Defense reaction in dentine 1 2 3 4 5 6 7 8  These (cont’d) crystals originate from the peritubular and intertubular dentine.  This process is known as TUBULAR SCLEROSIS.  It is seen clinically as yellow-brownish discoloration of the dentine.
  19. 19. Outer Carious Dentine Knoop Hardness Number 70 - bacterial invasion - unremineralizable - dead - without sensation 60 50 Dental Caries Inner Carious Dentine - minimal bacterial invasion - remineralizable - alive - sensitive 40 30 transparant zone 20 10 zone of almost total demineralization E-D Junction zone of partial demineralization 1000 2000 Sound Dentine 3000 µm Crystals in Tubule Lumen Peritubular dentine Intertubular dentine Bacteria Odontoblast Process
  20. 20. Dental Caries Two layers of carious dentine Outer (‘infected’)  Bacterial Invasion  Unreminerizable  Dead  Without sensation Inner (‘affected’)  Few Bacterial  Reminerizable  Alive  Sensitive
  21. 21. Dental Caries Remineralization of inner carious dentine Prerequisites physiological remineralization:  Presence collagen fibers  Living odontoblastic process External remineralization:  Saliva , calcium and phosphate  Exposure bio-active agents
  22. 22. Dental Caries Characteristics of occlusal caries Fissure enamel caries 1 2 3 4
  23. 23. Dental Caries Characteristics of occlusal caries 1 2 3 4 Fissure enamel and dentine caries
  24. 24. Dental Caries Characteristics of occlusal caries Fissure cavity 1 2 3 4 3.6 mm
  25. 25. Dental Caries Characteristics of occlusal caries Lateral spread of fissure cavity 1 2 3 4 3.6 mm
  26. 26. Dental Caries Dentinal lesion formation and progression: a summary 1  2   Enamel demineralization follows the enamel rods. Initial dentine demineralization does not spread along the Enamel Dentine Junction (EDJ) beyond the periphery of the lesion in the enamel. This leads to a cone shape lesion with the base at the EDJ.
  27. 27. Dental Caries Dentinal lesion formation and progression: a summary 1  In any pit and fissure system there can be multiple lesions in different stages of progression. (Stages A, B and C.)  Only when there is frank cavitation and a cariogenic environment, will dentine demineralization spread in a lateral direction. (Stage D) 2
  28. 28. Dental Caries Characteristics of approximal caries 1. Subsurface demineralization of enamel. 1 2 3 4
  29. 29. Dental Caries Characteristics of approximal caries 1 2 3 4 2. Partial demineralization of dentine directly underneath enamel lesion
  30. 30. Dental Caries Characteristics of approximal caries 1 2 3 4 3. The dentine demineralization follows the dentine tubules
  31. 31. Dental Caries Characteristics of approximal caries 1 2 3 4 4. Lateral spread of dentine caries occurs mainly in cavitated lesions
  32. 32. Dental Caries Characteristics of approximal caries : a summary  Progression of approximal caries follows the same principles as for occlusal caries.  It follows the enamel rods, but because of the curved shape of the approximal tooth surface, the lesion does not lead to a cone shape at the EDJ as present in an occlusal fossa.
  33. 33. Dental Caries Traditional concepts of cavity design 1  2 3 4  GV Black’s cavity preparations followed designs that were largely dictated by the physical properties of the filling materials (e.g., amalgam and silicate cement). These materials needed mechanical retention
  34. 34. Dental Caries Traditional concepts of cavity design 1 2 3 4 Mechanical retention  Flat floors  Vertical walls  Triangular retention niches  Undercut areas
  35. 35. Dental Caries Traditional concepts of cavity design 1  Shape of the prepared cavity was not limited to the tooth destruction caused by caries.  The preparation did not follow the way a dentine lesion progresses.  Black's principles could be considered as: 'the application of a mechanical design on a biological process' 2 3 4
  36. 36. Dental Caries Traditional concepts of cavity design 1 2 3 4 ‘The application of a mechanical design on a biological process'
  37. 37. Dental Caries Longevity of amalgam restorations  Research findings  survival time single surface: 10 – 8 years  survival time multiple surface: 8 - 6 years  Reasons for failures  secondary caries  marginal breakdown
  38. 38. Dental Caries Repeat restoration cycle 1 2 3 Repeat restoration cycle  Occlusal lesion and occlusal restoration  2-Surface restoration  Extended restoration  Crown or Extraction
  39. 39. Dental Caries Repeat restoration cycle  1 2 3  ‘Diagnoses’ are uncertain, with considerable variation occurring between dentists. Extensive cavity preparations (Black) in the name of outline form and extension for prevention result in restorations with weak margins, leading to marginal breakdown and ‘ditching’.
  40. 40. Dental Caries Repeat restoration cycle  1  2 3    Dentists have an urge to replace restorations Perceived (but erroneous) requirement to ‘freshen up’ the cavity walls and margins. The teeth inevitably become weaker, thereby reducing their prognosis. The complexity of the restorations increases or Tooth needs to be extracted.
  41. 41. Dental Caries Traditional approach: a Summary 1  2   Much sound tooth tissue needs to be removed. Traditionally placed restorations, on average, do not last long. The replacement restorations, in many cases, last for less time.
  42. 42. Dental Caries Traditional approach: a Summary  The end result is a tooth that became weaker and weaker each time a replacement was made.  The weaker the tooth becomes, the more likely the restoration will fail, resulting in a vicious cycle and termed the ‘repeat restoration cycle’. 1 2
  43. 43. Dental Caries Biological principals of cavity preparation 1  2 Cavity cleaning      Obtaining access Removal of dead dentine and enamel Anatomy determines the shape No preconceived cavity design Black's principles are redundant
  44. 44. Dental Caries Biological principals of cavity preparation 1 2
  45. 45. Dental Caries Appropriate instrumentation  Mechanical retention is no longer needed with adhesive materials.  Shape of the cavity is determined by the anatomy of the lesion. 1 2 3 4 5 6 7 8
  46. 46. Dental Caries Appropriate instrumentation  Question: 1 2 3 4 5 6 7 8 Is a rotary instrument the best tool when the cavity is determined by the anatomy of the lesion ?
  47. 47. Dental Caries Appropriate instrumentation  1 2 NO !!!! A rotary instrument is not the best instrument for: 3 4  removing only soft, completely demineralized tooth tissue and  preserving as much as possible remineralizable enamel and dentine. 5 6 7 8
  48. 48. Dental Caries Appropriate instrumentation  1 2 Hand instrument:  Dental hatchet 3 4 5 6 7 8 (e.g., 10 – 6 - 12)
  49. 49. Dental Caries Appropriate instrumentation  1 2 Hand instrument:  Excavator 3 4 5 6 7 8 (e.g., 153 – 154)
  50. 50. Dental Caries Appropriate instrumentation  Rotary instruments (only certain circumstances) 1 2 3 4 5 6 7 8  Slow speed drill  with straight bur for further opening of dentinal lesions that have a very small entrance  with round bur for gentle removal of dead tissue.
  51. 51. Dental Caries Appropriate instrumentation  Rotary instruments (only certain circumstances) 1 2 3 4 5 6 7 8  High speed drill  only for opening cavities that are inaccessible  removal of failed restorations.
  52. 52. Dental Caries Appropriate instrumentation  1 2 3 4 5 6 7 8 Why hand instruments?  creates the most ideal (conservative) cavity shape  gives the operator improved tactile sense  does not damage surfaces adjacent to the lesion, in the case of approximal lesions and  therefore, does not promote caries development.
  53. 53. Dental Caries Cavity restoration:      WHY To stop the caries process To facilitate plaque removal To encourage remineralization of inner carious dentine To restore function To restore aesthetics.
  54. 54. Dental Caries Cavity restoration:  HOW Application of a material that:  produces a seal against bacterial invasion  encourages remineralization  is sufficiently durable  maintains function.
  55. 55. Dental Caries Cavity restoration: WHICH MATERIAL  Adhesive restorative materials  composite resins and polyacid-modified composite resins (‘compomers’)  glass-ionomers and resin-modified glassionomers.  Non-adhesive restorative materials  amalgam
  56. 56. Dental Caries Tooth preservation versus cavity preparation 1 2 3 4 Preservation = restoration + prevention
  57. 57. Dental Caries Tooth preservation versus cavity preparation 1 2 3 4 Sealant restorations
  58. 58. Dental Caries Tooth preservation versus cavity preparation 1 2 3 4  For carious lesions in occlusal, buccal and lingual surfaces of posterior teeth:    Preventive resin restoration Preventive glass-ionomer restoration Atraumatic Restorative Treatment (ART )
  59. 59. Dental Caries Tooth preservation versus cavity preparation 1 2 3 4  For carious lesions in approximal surfaces of posterior teeth:    Box-type restorations (outcome: good). Tunnel preparation (outcome: dubious). ART (outcome: unknown yet).
  60. 60. Dental Caries Effect of sealed versus nonsealed restorations  Clinical trial in the USA.  more sound tooth structure was conserved  restoration margins were better protected  recurrent caries was less frequent  clinical survival of restorations was prolonged.
  61. 61. Dental Caries Summary 1 2 3 4  The biological principle to the management of a dentine lesion is to only remove soft, completely demineralized tooth tissue. This is best achieved through using hand instruments and/or a slowly rotating drill rather than a high-speed drill. In doing so, less sound tooth tissues are removed and damage to surfaces of other teeth is minimized.
  62. 62. Dental Caries Summary  1 2 3 4 Since only soft, completely demineralized tissue is removed, there can be no preconceived cavity design; the anatomy of the carious lesion dictates the size and shape of the cavity preparation.
  63. 63. Dental Caries Summary  1 2 3 4 The treatment is completed by placing an adhesive filling material into the cleaned cavity preparation, over its margin, and over the adjacent pits and fissures. This sealant restoration will arrest caries activity that is present in dentine and enamel, provided that the bonding of the material to these tooth tissues is adequately established.
  64. 64. Dental Caries Summary  1 2 3 4 This treatment modality has the potential to:     control dentine caries increase survival of the restoration save tooth tissues and thus increase tooth life expectancy.
  65. 65. Dental Caries  Remember:  TO APPLY PREVENTIVE MEASURES  TO ENCOURAGE ORAL HYGIENE AND  TO PROMOTE THE USE OF TOOTHPASTE. FLUORIDE

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