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To review the previous preventive measures against the incidence of dental caries in children, we started to examine the state of dental health in children at the age of 18 months. The annual dental examination continued up to 12 years of age (sixgraders). Enrolled in this study were a total of 225 children living in a Town T and born between 1980 and 1982.Meanwhile, we made surveys in order to gauge the degree to which the subjects and their parents have concern for oral health. The findings and their relationships to the caries incidence were analyzed using an epidemiological technique. The annual dental examinations revealed that in primary dentition the incidence of caries tends to increase in 3·year-olds while in permanent dentition the carious process extends in 4-6 graders.By kind of teeth, primary molars accounted for 52% of the affected deciduous teeth. First molars made up 72% of all the decayed permanent teeth.Using the two caries cumulative indexes developed by our department for recording the prevalence and severity of tooth decay in the deciduous dentition and in the permanent dentition, respectively, we found that there is a correlation between the incidence of caries in the deciduous dentition and that in the permanent teeth.The two formulae are based on the cumulative number of decayed teeth that appeared in the deciduous dentition and permanent dentition for a given period of time.In order to find whether there is any correlation between caries attack and attention paid to the risk factors, we divided the subjects into two groups by the number of decayed teeth per person. In the group made up of those with many carious teeth, it was noted that between-meal snacks are most likely to produce caries in deciduous teeth, while lifestyle affects permanentteeth.

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We conducted research on the dental health and hygiene activities in schools and the number person-days per year for activities in order to examine the manpower volume of dentists and dental hygienists which is necessary to put into practice dental health and hygiene activities equally in all schools throughout the country.The followinng results were obtained. 1) Periodic and preschool dental health examinations have been carried out in all schools throughout the country. However, the practic of other dental health activities was as low as 30% in primary schools and 20% in secondary schools.2) In the schools which have carried out dental health activities, 70% of the dentists among all the schools joined in every activity and 30% to 67% of the dental hygienists among all the schools joined in every activity excepting dental meetings.3) The mean number of yearly average of person-days for dental activities for a school was different according to the number of schoolchildren. Primary school dentists worked for 3 to 10 person-days and secondary school dentists for 2 to 8 person-days. They alotted 70% of all the person-days for dental examinations. Dental hygienists assigned 2 to 5 person-days in primary schools and 1 to 2 person-days for average yearly dental activities.4) The yearlong activity person-days for a school practicing in the dental health activity were subdivided into the values of 50%, 75%, 80%, and 90% by the number of schoolchildren for the dental examination.The necessary yearly activity person-days were from 5 to 13 (50%) and 13 to 31 (90%) for the dentists, and 11 to 16 (50%) and 24 to 43 person-days (90%) for the dental hygienists.5) The necessary yearly person-days (50-90%) according to regions were 9 to 20 person-days for a dentist and 26 to 63 person-days for a dental hygienist in towns and villages of 10,000 people, and 5 to 12 for a dentist and 15 to 37 for a dental hygienist in cities and wards of 50,000 people, and 4 to