A comparison of alveolar bone in young and aged mice.

To study the relationship between aging and alveolar bone loss, the periodontia of young (12-week-old) and aged (94-week-old) C57B1/6 Nia mice were compared, giving special attention to the alveolar bone. The tibiae were also examined to distinguish local from systemic bone changes. The mean area of interproximal bone between the first and second mandibular molars was significantly less in the aged mice than in the young mice. While there was no difference in the distance from the cementoenamel junction (CEJ) to the alveolar crest, the width of the interproximal bone was narrower in the aged animals. The cross-sectional width of the tibia was also reduced in the aged mice, although the total bony area remained constant. In both groups of animals, the distance from the apical extent of the inflammatory infiltrate to the alveolar crest was similar suggesting that alveolar bone loss was not related to inflammation. Other histologic features observed in the teeth of the aged mice, which may have influenced the amount of alveolar bone, were mesial tilting and distal drifting, occlusal wear, and passive eruption. These findings suggest that the greater bone loss in the aged mice may be more related to the aging process and to the functional changes of tooth movement associated with aging than to periodontal disease.