Occlusal tooth wear in female F344/N rats with aging.

This study was conducted to ascertain whether laboratory rats are an adequate animal model for aging oral cavity research, especially on occlusal tooth wear (OTW), which progresses with aging and causes abnormal occlusions. Mastication has been reported to relate to cognition in the elderly. Thus, it is important to care for the oral cavity, especially in the frail elderly, for the maintenance of all-round quality of life. Adequate and appropriate animal models are essential for basic and clinical research on the oral cavity.Dried maxilla and mandible specimens from 98 young, aging or aged female F344/N rats were used.The levels of OTW of all molars were monitored with aging. The molar tooth began to wear at 1-month old (M) and progressed rapidly till 12M. Subsequently, OTW progressed slowly till 30M, and then rapidly again after 35M.This study showed that progress of OTW is well correlated with the entire life span of the rat, and suggested that the rat aged over 12M would be an adequate animal model for research on OTW in middle-aged and elderly people.