抄録
We investigated the relationship between the human life span and the life of the average tooth. Although Japanese woman live longer than man, the opposite is true for their teeth. We also foung that longevity was different for each tooth. During the six years from 1987 to 1993 the increase in longevity of the average Japaneese tooth was three times greater than the increase in the average life span. In order for people to achieve the goal of having 20 teeth by age 80, they must consider different preventive measures for each tooth.