Tonna, E. Factors (Aging) affecting bone and cementum. J. Perio., 42: 267; 1976.

Study Aim

Methods and Materials

Alveolar bone changes with age

• According to Gottlieb and Orban with advancing age alveolar bone resoption occurrs and may be related to gingival recession.
• Alveolar process resorption is known to occur without the former loss of dentition. BNL studies showed extensive resorption of the alveolar crest and bone and no tooth loss.
• Osteoporotic changes in the mandible increase with age. In the BNL the interradicular bone exhibits continuous remodeling throughout its life span.
• Marrow spaces of the alveolar bone also showed changes with advanced age.
  a. In man red marrow is replaced with fattty marrow.
  b. In mice the molars exhibit mesial drift, and resorption of periodontal process continues at the mesial surface. Alveolar process becomes essentially free of vascular and marrow channels.
• Periosteal and endosteal cells numbers decrease per unit of surface exposed.
• Active surface osteogenic cells are decreased, resembling fibrocytes.
• Endosteal cells generally reveal persistent activity, so that age changes are delayed at the interradicular region.
• Osteocyte changes are observed once formed. Matrix production continues to occur resulting inthe formation of definite lacunae.
• Autoradiographic studies using H 3 Thymidine showed:
  a. Cellular proliferative activity of the osteogenic cells is extremely low.
  b. Crestal labeling is elevated in old animals with inflammation.
  c. In response to trauma, some diminish activity and delay in response is observed at the alveolar crest and mesial alveolar bone surfaces.
• The studies showed the existence of 2 modes of dental bone activity:
  a. Alveolar bone: High rate of matrix production and discreate labeling.
  i. With increasing age, activity diminishes progressively.
  ii. Crestal activity is turned off before 26 weeks.
  b. Basal bone
  i. Matrix activity is high initially.
  ii. Decreased activity is observed with increasing age
• Mesial and coronal periosteal surfaces show the basal bone type of activity.
• Distal periosteal surfaces and interradicular endosteal surfaces reveal the alveolar tyoe of activity.

• Cementum apposition is continuous throughout life.
• Acellular cemental deposition at apical 1/3 .
• It accumulates in large quantities along the interradicular surfaces of the tooth.
• Continual reapposition of new layers of cementum represents the aging of the tooth.
• Deposition appears to occur in response to functional stress, but must be pointed out that layers of cementum are found at the roots of unerupted teeth of aged individuals.
• Often excementosis are formed leading to ankylosis with alveolar bone.
• Aging of acellular cementum is not readily discerned microscopically as compared to the cellular cementum, where there is degeneration and death of cementocytes .
• The cellular proliferative activity of cementum is low.

Conclusion

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