Abstract
Daily toothbrushing frequency by age and period were analyzed using isometric line map method and Bayesian cohort models in order to investigate the effects of period, age and cohort (generation) on the toothbrushing behavior of the Japanese. Data sets are from four recent reports on the Survey of Dental Diseases conducted by the Ministry of Health and Welfare. 1. More than 90 % of males aged from 13 to 65 and females aged from 5 to 74 were brushing every day in 1993. The percentage of males brushing every day increased over the period, while that of females reached a ceiling in 1987. 2. It seems that females in their twenties take the lead in Japanese toothbrushing behavior in every frequency affected by age. 3. For both males and females born after 1955, the proportion of persons brushing once a day decreased and those brushing twice or more a day increased. These changes suggest the influence of school education. 4. For elementary school children, persons in their twenties and the aged, the percentage of persons brushing three or more times a day increased over time. However, strong cohort effects could not be detected, which suggests brushing three or more times a day may not be habitual. 5. It has been thought that the purpose of toothbrushing is to prevent dental diseases, but the results of the present study suggest that toothbrushing behavior is more related to the degree of one's concern about his social activity and relationships.
