Alveolar bone loss of senescence-accelerated mouse (SAM).

SAM-R/1/Iw (senescence-accelerated mouse, resistant) and P/2/Iw (senescence-accelerated mouse, prone) under a conventional environment and eating standard pellets were examined for alveolar bone loss and the presence of periodontitis around maxillary and mandibular molars as a function of age. Neither SAM strain manifested a chronic periodontitis similar to that in humans, and no obvious plaque and calculus were observed. However, in both strains, 15% of M3 was lost after 13 months of age, and alveolar bone loss gradually increased with advancing age. Though there was no significant difference in the incidence of M3 loss between the two strains, P/2/Iw showed a higher alveolar bone loss around all molars than did R/1/Iw after one month of age throughout their life span. For M1, the difference in alveolar bone loss between P/2/Iw and R/1/Iw was significant, and it was probably caused by the difference in degree of molar eruption. Other factors, such as occlusal trauma and gingivitis, may play some role in alveolar bone loss.