An Epidemiological Study of Caries Prevalence in School Children in Hokkaido, Tokyo, and Okinawa

Abstract

The dental health of 8, 672 school children, aged 6 to 14 years, resident in Hokkaido, Tokyo, and Okinawa was surveyed in 1977-1978. The purpose of this study was the comparison of caries prevalence of different areas in Japan.
Dental caries prevalence in these areas is shown in Figs. 1, 2, and 3. The children resident in Tokyo showed the best condition of dental health, and the children resident in rural areas in Hokkaido showed the poorest condition. The children in Hokkaido had many more carious teeth among the anterior teeth than Tokyo and Okinawa children, and about 20% of the children in the 2nd grade of middle school had cervical carious lesions in the frontal teeth. From the study of these age groups in seven locations, it was concluded that labial carious lesions among the anterior teeth appeared when the caries prevalence rate of anterior teeth reached about 20% in children.
A questionnaire on the frequency per day or week of drinking soft drinks and the frequency of daily tooth brushing was given to the 6th grade of primary school and to middle school children in Hokkaido. The children who more frequently drank soft drinks had a tendency to more carious teeth. The correlation between the frequency of daily tooth brushing and the dental caries prevalence was not clear in this study.
The sugar contents and pH of ten soft drinks were analyzed. Sucrose content of soft drinks ranged from 8.3 to 14.1 grams per 100 ml and glucose content was 0.13 to 3.42. The pH was between 2.5 to 3.5.
In addition to the results of the questionnaire, the annual survey of nutrition in Japan has suggested that recently, Hokkaido people drink more soft drinks than other Japanese people. I conclude that the caries prevalence and carious lesions of the anterior teeth are increased in Hokkaido as compared with Tokyo and Okinawa mainly due to the frequent use of soft drinks.