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age change in dental hard tissue

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age change in dental hard tissue

  1. 1. PR ESENTED BY JigyashaTimsina BDS 2nd year
  2. 2. AGING  Definition : Refers to irreversible and inevitable change that occurs with time  It is also defined as sum of all morphological and functional alteration in an organism that leads to functional impairement
  3. 3. BIOLOGICAL AGING PROCESS IS :  Universal : detectable in all members of the species  Progressive: develop gradually and irreversibly  Deleterious : harmful to the survival of individual
  4. 4. AGING AND THE HARD TISSUES
  5. 5. ENAMEL DENTIN CEMENTUM ALVEOLAR BONE DENTAL HARD TISSUES
  6. 6. ENAMEL CHANGES  Attrition  Change in permeability  Discoloration  Chemical and surface changes
  7. 7. ATTRITION  Physiological wear of occlusal or incisal and proximal surfaces of teeth resulting in a decrease in vertical dimension  In severe attrition dentin may be exposed
  8. 8. CHANGE IN PERMEABILITY  Young enamel acts as a semi-permeable membrane and permits slow passage of water and molecular substances through the pores between the crystals.  With age the enamel crystals grow in size and the pores between them is obliterated resulting in reduced permeability of the enamel.
  9. 9. DISCOLORATION  Normal: white to yellowish white.  With age darkening seen.  Thought to be because of: I. Loss of enamel rods- this loss alters the light reflection of enamel and results tooth color change. II. Deepening of dentin color seen through progressively thinning layer of enamel.
  10. 10. CHEMICAL AND SURFACE CHANGES  Increase in fluoride and nitrogen content.  Water and organic content decrease with age.  Reduction in organic content reduces chance of caries in teeth with age.  Loss of Perikymata
  11. 11. DENTIN The main changes in dentin associated with aging are  Increase in sclerotic dentin.  Increase in the number of dead tracts.  Increase in formation of reparative and reactive dentin.  Vitality of dentin
  12. 12. DEAD TRACTS  In normal dentin the odontoblastic processes may disintegrate and the empty tubules get filled with air. These are called dead tracts.  They appear black in transmitted light and white in reflected light.  In narrow pulpal horns degeneration of odontoblast seen due to crowding of odontoblasts.  thought to be the initial step in the formation of sclerotic dentin. Dead tract
  13. 13. SCLEROTIC DENTINTRANSPARENT DENTIN  Refers to the dentinal tubules that have become occluded with calcified materials.  It may be result of the aging process and called physiologic dentin sclerosis or may occur due to some irritation like caries, attrition, abrasion and called reactive dentin sclerosis  When this occurs in several tubules in the same area , the dentin assumes a glassy appearance and become transparent
  14. 14.  Most common in apical 3rd of the root.  It appears transparent or light in transmitted light and dark in reflected light. Sclerotic dentin
  15. 15. REPARATIVE –REACTIVE DENTIN  If the provoking stimulus cause destruction of the original odontoblasts, the new, less tubular dentin formed by newly differentiated odontoblast like cells is called Reparative dentin.  However if the odontoblast survive the provoking stimuli the dentin produced by them is called Reactionary dentin
  16. 16. Reparative dentin Reactive dentin
  17. 17. VITALITY OF DENTIN  Since the odontoblasts do not degenerate normally, dentin is laid down throughout life.  Although after the teeth have erupted and become functional dentinogenesis slows and further dentin formation is at much slower rate
  18. 18. CEMENTUM  Hypercementosis .  Cementicles.  Change in permeability.  Cementum re-absorption and repair
  19. 19. HYPERCEMENTOSIS  It is an abnormal thickening of the cementum.  may be generalized or localized ,diffused or limited.  Hypercementosis is termed cementum hypertrophy if the overgrowth improves the functional qualities of the cementum and is termed cementum hyperplasia if it is not correlated with increased function.
  20. 20. FIG : A FIG : B
  21. 21. CEMENTICLES  They are ovoid or round calcified structure that are formed as a result of calcification of the degenerated periodontal tissue or the epithelial rests of Malssez.  Cementicles may be: 1. Free in the periodontal ligament. 2. Attached the cementum 3. Embedded in the cementum FC-free cementicle SC-sessile cementicle
  22. 22.  Permeability : The permeability of cementum decreases gradually by age. The permeability from the periodontal side is lost except in the most recently formed layer of cementum, while that from the dentine side remains only in the apical region.  Cementum Resorption and Repair: Cementum resorption can occur after trauma or excessive occlusal forces . After resorption ceases, the damage is usually repaired. If the repair establishes the former outline of the root surface it is called anatomic repair. However if only a thin layer of cementum is deposited and the root outline is not constructed it is called functional repair.
  23. 23. ALVEOLAR BONE  Bone resorption is the major age change in alveolar bone.  Common site of resorption- labial aspect of alveolar crest.
  24. 24. Bone reabsorption Decrease in height and width of the jaw Distance between the crest of the alveolar bone and cemento-enamel junction increase Alveolar sockets appear jagged and uneven
  25. 25. OTHER CHANGES  The marrow space have fatty infiltration.  Loss of maxillary bone is accompanied by increase in size of maxillary sinus.  Internal trabecular arrangement is more open which indicate bone loss.
  26. 26. REFERENCES  Orban’s oral histology and embryology  Ten Cate’s oral histology  Oral anatomy ,histology and embryology Berkovitz , Holland , Moxham

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