The aim of this study was to determine regional differences in caries prevalence among 3-year-old children. Caries data on 35,954 3-year-old children, residing in 6 districts of Okayama city between 1998 and 2004, were obtained from the records of public dental health check-ups. Caries prevalence in each district was calculated separately. Multilevel analysis with two levels was applied using the yearly variation as level 1 and spatial variation as level 2. In the fixed part, the slope of caries prevalence according to year was -2.156, indicating a decrease in caries prevalence during the study period. The intercept of the model was 38.656. In the random part, the variances of the intercept and slope in level 2 (spatial variation) were 6.992 and 0.018, respectively, which suggested a spatial variation of caries prevalence in this city. The negative covariance of the intercept and the slope (-0.624) demonstrated that the district with a higher intercept exhibited a greater decline in caries prevalence. It was concluded that changes in caries prevalence among 3-year-old children varied according to district, where the same dental health service is provided equally.

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We assessed the relationship between clinical and bacteriological indicators on the efficacy of oral care. The subjects comprised 27 patients of a rehabilitation hospital in Iwate prefecture. We evaluated the oral status of the subjects clinically via inspection of the tongue coat volume (tongue coat score), CPI, and measurement of oral malodor (VSC: H_2S and CH_3SH levels). Subsequently, tongue coat samples were collected from the subjects for biological assessment. These samples were weighed and applied to real-time PCR to quantify the total bacterial cells. Examinations were performed both on admission and two months after admission. At two months after admission, clinical indicators were improved, especially the tongue coat score, CPI, and CH_3SH level. For the bacteriological indicators, the tongue coat volume was reduced significantly and the mean number of bacterial cells in the whole tongue coat sample tended to decrease. However, the mean number of bacterial cells per 1mg of tongue coat was almost the same. A correlation was observed between the H_2S level and the number of bacterial cells per 1mg of tongue coat. In step-wise multiple regression models in which the dependent variable was the number of bacterial cells in the whole tongue coat, the tongue coat score and H_2S level were both significant variables. In conclusion, assessment of the tongue coat volume and oral malodor via the H_2S level were efficient clinical indicators to deduce bacteriological changes after oral care.

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Recently, a decline in dental caries prevalence in schoolchildren has been reported in the majority of highly industrialized countries. However, it is a problem that schoolchildren with a high incidence of caries still exist, although their number is limited. Therefore, it is necessary to guide and manage schoolchildren in consideration of their caries risk for oral health promotion. At two elementary schools in one town in Kagoshima, we carried out caries risk tests for all children during school dental examinations. We selected 211 children in the first to forth grades at the baseline who had undergone examination 3 times during 2 years. They were divided into two groups according to the DMF score at the baseline (DMF=0 group, 118 subjects; DMF≧1 group, 93 subjects). The saliva-buffering capacity and acid-producing ability of dental plaque were scored from 0 to 2, respectively, and the sum of each score was used as a caries risk index (0 to 4). In the DMF=0 group, the schoolchildren with a lower risk of dental caries showed a lower increment of caries lesions. There was a significant difference in the degree of caries risk between subjects who showed and did not show caries increments (Mann-Whitney's U test, p<0.05). In the DMF≧1 group, there were no significant differences in the degree of caries risk between the two groups. A high risk population was included in the subjects who had no caries lesions and appeared to have a good oral condition at the baseline, and children in such population showed a high rate of caries increment in the following two years. The results suggest that the caries risk tests in school dental examinations are useful to predict future caries development.

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A survey was performed in 2001 in company employees about their dental health service sponsored by the Japanese Foundation for Oral Health Promotion. The questionnaire consisted of a total of 13 items: five items regarding subjective symptoms within the oral region, four items concerning eating and smoking habits, and four items related to oral health behavior. The people surveyed were male, aged from 40 to 59, recruited from participants in the occupational dental health service sponsored by the Japanese Foundation for Oral Health Promotion as part of its occupational oral health services. To assess the effect of the oral health programs, the subjects were divided into two groups: one consisting of those who had frequently participated in the programs, and the other comprised infrequent attendants. The results of the survey concerning the above-mentioned 13 items were tested by a X^2 test and studied using logistic regression analysis. The X^2 test, performed separately, showed favorable results in eleven of the 13 items in the two age brackets of the frequently attending group. Logistic regression analysis revealed that frequent attendance had a strong influence on the "proper method of toothbrushing" and the "habitual use of instruments for proximal cleaning". The oral health program primarily includes guidance on oral cleaning in accordance with the intraoral state and preservation of oral health by dental health professionals. In the present study, the frequently attending subjects were found to be taking good oral care by practicing toothbrushing adequately and other prophylaxes. In conclusion, the results of our survey provided evidence concerning the effectiveness of the oral health service.

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The objective of this study was to clarify factors affecting the prevalence of dental caries in children 1.5 (one and a half years old) and 3 years of age in Onomichi to establish regionally practical and effective preventive measures against dental caries. In medical check-ups at 1.5 and 3 years of age, a questionnaire survey of life styles and child-care environments and a dental check-up were performed, and their relationship was analyzed by logistic regression analysis. The factors strongly associated with dental caries development by 1.5 years of age were 'feeding before sleeping', 'breast milk feeding', and 'time of initiation of sweet food ingestion'. As for the development of dental caries between 1.5 and 3 years of age, 'frequency of drinking sports-drinks', 'feeding before sleeping', and 'frequency of drinking juice' were strongly associated. The habits acquired by 1.5 years of age, such as 'frequency of eating between meals', 'regularity of eating between meals', 'frequency of drinking juice', 'frequency of drinking sports-drinks', 'drinking and eating before sleep', 'watching TV during meals', and 'frequency of completely brushing', continued until 3 years of age. The 'regularity of eating between meals' and 'frequency of completely brushing' were likely to change to good habits between 1.5 and 3 years of age, and the 'daily juice intake' and 'frequency of drinking sports-drinks' increased. For dental health instruction for infants, consideration of items to be emphasized depending on age is necessary.

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We attempted to determine the level of knowledge concerning the transmission of cariogenic bacillus from parent to child and also the relationship between periodontal diseases and premature delivery in a study of pregnant and nursing mothers. The subjects were enrolled from 2 groups of women living in Sasebo City, Japan, comprising 65 pregnant mothers who had recently given notice of their pregnancy to the city health department and 140 nursing mothers participating in oral health education for their 10-month-old children on February 2006. The frequency of correct answers was higher in the group of nursing mothers than the pregnant subjects. Among nursing mothers, those who had dental problems during pregnancy tended to give more correct answers than those who did not have such problems. The results suggested that health education during pregnancy was likely to be effective for promoting dental health knowledge.

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To assess the current status of health policies for fluoride use at the local government level in Japan, we carried out a national level mailed questionnaire survey in January, 2005. The targeted recipients were prefectures, major cities, and special wards throughout Japan. The main questionnaire items were concerned target values, programs, and educational materials about fluoride use in each municipality. Officials of departments which were in charge of dental health answered this questionnaire. The response rate was 98% (46/47) among prefectures and 94% (75/80) among other municipalities. Eighty-three percent of prefectures and 55% of other municipalities had target values for fluoride use. Seventy percent of prefectures and 77% of other municipalities had implemented health programs involving fluoride use. Sixty-one percent of prefectures and 25% of other municipalities had some form of guidelines regarding fluoride use. Fifty-seven percent of prefectures and 40% of other municipalities published educational materials regarding fluoride use. These results indicated that national fluoride use policies contributed to promoting fluoride use at the level of local government in Japan. However, fluoride use in Japan has not yet become well established. Therefore, further efforts are needed to promote its use.

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