With the intention of accessing the new principle of oral health guidance, oral examination, dietary study and questionaire to 128 students of our dental school have been carried out, after realizing the characteristics of the living way of the youth of present day, centering around the dietary life, evaluating the numerical relation between food and numbers of decayed untreated teeth. As the results of this study the following six items, sex, commuting way to school, mode of food, chewing consciousness, irregular time schedule of supper and the amount of canned coffee taken daily, have significant correlation with the numbers of decayed teeth. Further study has found the facts that major reason of increasing the number of decayed teeth was daily intake of more than two cans of coffee and the most effect 've way to decrease the number was to stop taking canned coffee. This study has made clear the facts the intake of canned coffee by present youth becomes habitual and the amount of intake is bigger than expected, and this has an important accelerating effect of increasing the numbers of decayed teeth. This study suggest that the improvement of living style, especially dietary life have an effective help to increase oral health conditions.

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The present study investigated the nutritional and diet conditions of 80-year-old Japanese persons retaining 20 teeth per individual. Two groups of elderly Japanese aged over 80 years were investigated regarding the nutritional value of their diet. The case groups were in Tokoname-city, Aichi Prefecture, Japan and were composed of 54 elderly persons having 20 or more natural teeth (average 24 teeth) and a control group consisted of 51 elderly persons having less than 20 teeth (average 3 teeth). The results can be summarized as follows. 1) Low intake of energy was observed in the 8020 group compared with the controls. 2) Low intake of carbohydrate was observed in the 8020 group. 3) The 8020 group ate many kinds of food. 4) No differences were observed in the other intake of nutrients. It was comcluded that the elderly persons having 20 or more natural teeth tended to have a low intake of energy and a variety of foods.

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The periodontal conditions of 316 adults on an island of Nagasaki Prefecture in Japan were examined in a community dental health examination project. Among them, 130 subjects (or 3137 teeth) were re-examined to evaluate the effect of the project. The following three indices were used to evaluate the periodontal conditions : 1) the highest CPITN score for each subject (CPITN by person) 2) the CPITN score of the index tooth for each sextant (CPITN by sextant) 3) the CPITN score of each tooth (CPITN by tooth) Changes in periodontal conditions after the community dental health examination were assesed from changes in individual periodontal conditions by observing significant changes in each tooth, as well as on a tooth basis. The results were as follows : 1) The subjects had more missing teeth than the average Japanese, and their initial periodontal conditions were worse than the previous study on Japanese. 2) The inghest CPITN scores could be used for examining the age-related changes in periodontal conditions up to 40 years of age. The CPITN per tooth was more suitable for evaluation in the older age group, mainly to avoid the effect of missing teeth. 3) On the individual basis, 32.3% were improved and 43.8% did not show significant changes in periodontal conditions after the project. On the tooth basis, 33.0% were improved and 42.0% maintained the initial conditions. The subjects with improved periodontal conditions lost fewer teeth than the subjects with worsened or repaired teeth. 4) The highest needs for periodontal care were observed among persons in their forties and fifties according to the number of the teeth which needed scaling. Prevention of periodontal diseases should be emphasized in younger adults and dental care in the older adults for prevention of tooth loss.

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There is still much to be desired in adults oral hygiene for the preservation of oral health. It is necessary to work out a more efficient educational program. To implement the program effectively, it is necessary to divide the subjects into those who are aware of the importance of oral hygiene and compliant with hygienists instructions (concerned group) and those who are indifferent to oral hygiene (indifferent group). The present study covered a total of 699 male employees, aged 30-59 years, of companies which regularly sponsor dental health projects. By the number of times they do mouth cleaning per day, when and how, they were divided into the concerned group and the indifferent group. In order to look into the difference in concern for health between the two groups, differences in the results of oral examinations, oral health status and lifestyle were analyzed using the contingency table and Hayashi's quantification methods II and III. As a result, it was found that the concerned group has the edge on the indifferent group in many respects of the health concern such as "having received dental treatment," "being nonsmokers or having quitted smoking," "leading a well regulated life," "exercising regularly," and "receiving a regular health checkup." The point is that to provide oral hygiene guidance effectively to adults, the subjects should be divided into groups based on the analysis their health coping behavior.

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Pits and fissure sealant is an ideal preventive method and has been widely used in pediatric dental practice. There is on the market a sealant material which contains filler particles (60 % wt) to improve retention rate. The filler particles are made from submicronic, spherical, inorganic material. The purpose of this study was to compare clinically a filled visible-light cured sealant (Palfique Light Sealant ; PLS, Tokuyama Co.) with an unfilled visible-light cured sealant (Teeth Mate-A ; TMA, Kurary Co). Children (mean age 7 year 9 month) were selected who had a pair caries-free first permanent molars in the same arch. The two materials were bilaterally sealed in 41 pairs of teeth (18 maxillary and 23 mandibular first permanent molars) on the same day. The children were reexamined at 1, 2, and 4 months and then every 4 months after sealant application for a total of 24 months. The results were as follows. 1) Neither of the sealants were completely lost. 2) Complete retention rates at occlusal surface of maxillary were 100% and 100% in PLS, and 94.9% and 88.9% in TMA at the 12-and 24-month examination. Complete retention rates at the occlusal surface of the mandibular were 95.7% and 82.6% in PLS, and 87.0% and 82.6% in TMA at the 12-and 24-month examination. We found that the complete retention rates decreased each year for each material except at the occlusal surface of the maxillary for PLS. There was no statistically significant difference in the complete retention rates between the two materials at any time. 3) We observed that bubbles were contained in the materials. The incidence of bubbles was higher in teeth sealed with PLS than in teeth TMA. In this study, we did not find any superiority of the sealant material which contained filler particles.

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An in vitro pH cycling system was used to investigate the reaction patterns of human enamel and root dentine samples. Both proximal surfaces of 10 premolars from 10-year-olds and 10 from 50-year-old subjects were analyzed by lesion depth and mineral distribution pattem measurements by microradiography. Each 24-hour pH cycling regimens of demineralization and remineralization were done in the order of dem./rem./dem./rem. and dem. for a total of 5 days. There was no change of lesion depth between mesial and distal proximal surfaces in any subject, and the deepest lesion depth in root dentine from 50-year-old subjects was approximately 150μm. Compared with the root dentine of 10-year-old subjects this value was statistically significant (p<0.01), although there was no statistically significant difference in lesion depth of the enamel. Mineral distribution pattem of enamel samples from both groups of subjects mainly showed subsurface lesions with one thick surface layer. Appearance of the lamination type of leions was restricted to 4 enamel samples from 10-year-old subjects. In root dentine samples from both subjects, remineralization was confirmed in cement and dentine simultaneously. Hyper-remineralized cement was found in the 3 cases of 10-year-old subjects and in 2 cases of 50-year-old subjects. Mineral distribution of the hyper-re-mineralized layer on top of the lesion ranged from 60%/vol to 70%/vol. In the current investigation, a tendency toward forming subsurface lesions with a rather thick enamel surface was seen if demineralization were followed by remineralization at similar time period. Considering thot remineralized enamel and root dentine are more resistant to cariogenic challenges, this finding was also clinically important.

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Few studies have been conducted for the analysis of oral health services by local governments. The purpose of study is to evaluate the oral health service of Japanese local governments. The department of health of 44 local governments are replied to our questionnaire. The results are as follows ; 1. From 1989 to 1994, the number of oral health projects and the budgets for oral health were rapidly increased due to the project 8020, revision of the dental hygienist law, and other factors. 2. Oral health service for child and mother (70.5%), oral health service for the bed-ridden aged (61.4%), and project 8020 (56,8%) had higher rates than other service. 3. Many oral health projects of Japanese local governments are financially supported only by the local government. It is necessary to consider improvements for the continuation of these projects. 4. 63.6% of local government offices have a dentist or dental hygienist as dental officer and project health manager. 5. 9.1% of the health departments have a dental section, 22.7% have a child and mother or another dental section, and 13.6% have only a dental officer. A non-dental section has charge of dental health in 54.5% of local governments. 6. All of the local governments which have a dental section have a dentist or dental hygienist for dental officer and project manager. 7. 56.8% of local governments have a committee for Promoting Oral Health. 67.9% of local governments which have projects managed by a dental health officer (dentist or dental hygienist) have this committee. On the other hand, only 37.5% of local governments without a dental health officer have such committee. 8. The average number of oral health services by local governments which have a dental health officer is 9.5. On the other hand, the average number of such services by local governments without a dental health officer is only 6.2. 9. It is necessary to develop of the oral health system of local governments to improve the oral health service.

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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.

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We conducted a survey in order to study how the general public perceive dentistry in the social context in contrast with nine other medical disciplines : internal medicine, dermatology, psychiatry, surgery, otolaryngology, ophthalmology, pediatrics, obstetrics and gynecology, and orthopedic surgery. The survey was conducted from April 1992 through March 1993. The subjects were 99 male and 162 female residents of the city of Nagoya and its neighboring areas in Aichi Prefecture, with agesranging from 7 t6o 80. The subjects were asked to state their images of 10 medical disciplines including dentistry. Their images were classified into 163 code items. Of these items, the most frequently used were 51, 49, 32, 21, 28, 30, 34, 24, 27, and 34. Correspondence analysis was applied first to these image items for each of the 10 medical disciplines, and 5-dimensional item scores as well as subject scores were computed. Second, multiple regression analysis was applied to each of the 5-dimensional subject scores for each medical discipline. Predictor variables in these regression analyses were : (1) how long each subject had experienced medical treatment, (2) gender, and (3) age. At least one multiple correlation coefficient out of the five dimensions was statistically significant for four medical disciplines. They were dentistry, psychiatry, obstetrics and gynecology, and orthopedic surgery. Finally, a cross-classification table was constructed from the data, whose rows and columns were, respectively, the 10 medical disciplines and the 163 image items. Correspondence analysis for this crossclassification table indicated that (1) dermatology and ophthalmology were perceived as similar, (2) surgery and orthopedic surgery, and dentistry and internal medicine were also perceived as similar, and (3) obstetrics-gynecology was perceived as isolated from the other medical disciplines.

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A retrospective investigation was undertaken to clarify the frequency of premolar hypoplasia resulting from serious deciduous dental caries (Turner's tooth) in 1991. 920 premolars of 155 children in the 4-6th grades of primary school (9-12 yr old) in E town, Hokkaido were studied. The survey was carried out only by visual examination with dental mirrors and explorers at the time of the annual oral checkup in schools. 18 premolars which were regarded as hypoplastic successors caused by periapical inflammation were observed in 155 children. 14 were detected among 433 premolars which had been recorded as permanent successors of serious carious teeth in deciduous dentition. 8 of those 14 hypoplastic premolars had only white spots and/or yellow pigmentation and 6 of them had enamel defects. Likewise, 4 teeth of the other 487 premolars which had been recorded as permanent successors of sound, slightly carious or filled teeth, were also observed as hypoplastic due to local causes, but none of those had enamel defects. There were no significant differences in frequency of hypoplasia between upper and lower jaw, or males and females.

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The purpose of this study was to evaluate the value of the oral health program for adults which was regularly carried out by the local government on a community basis. An oral health survey was conducted for 1,311 persons living in Itakura-machi, Niigata Prefecture, which had population of 8,170 in 1994. Of these, 309 persons had participated in the program at least once before 1993 (experienced group). The others, 1,002 persons, had no experience of such a program (inexperienced group). The results from cross-sectional analysis in 1994 showed that the mean number of missing teeth in experienced groups was significantly fewer (p<0.05, 0.001) than in the inexperienced group in 55-59, 60-64 and 65-69-year olds, and the mean number of filled teeth in the experienced group was significantly greater (p<0.05, 0.01) than in the inexperienced group in 55-59 and 65-69-year olds. However, no significant differences were found in the mean number of decayed teeth and in the percentage of persons without untreated teeth between both groups in each age group. On the other hand, the longitudinal analysis, which showed no significant difference in the mean number of missing teeth between both groups, clearly indicated that oral health program based on examinations did not contribute to reduction of tooth loss. Therefore, for promoting or maintaining oral health the program should also include oral health instruction or education rather than only oral examinations.

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Oral health status and cause of tooth loss were studied in 1060 mentally retarded individuals who were admitted and resided in an institute during the period of 1971-1988. Our study cohort comprised 7-14 % of the estimated total of profoundly to moderately retarded persons in the general population. The estimate was nearly 10 thousand among the approximately 2.5 million general population of Niigata Prefecture throughout 1971 to 1988. A higher mean tooth loss was associated with increasing age : 1.2 in 6-14-year-olds and 6.6 in 35-44-year-olds in the 1970's, and 0.7 in 6-14-year-olds and 9.1 in 45-54-year-olds in the 1980's. These values were approximately 2-4 times higher in all ages but more than 15 times in 6-14-year-olds and in the 1980's diminished a bit in 45-54-year-olds than the values in the general population. Age and caries experience (DMFT) have been statistically proved to be significant risk indicators or factors of severer tooth loss in all ages through the life of mentally retarded persons.

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