We have been engaged in starting up fluoride mouthrinse programs in many communities. We have answered many questions about the programs asked by dentists, teachers and public health nurses. We have entered information about these activities in a database since October 1990. We recorded only lectures in 15 items of the database for 13 months. Since November 1991 we have recorded not only lectures but also communications between communities and us by telephone, facsimile, and mail in 4 items. The database consisted of 1,169 records at the end of 1994. Because the number of the records has increased regularly since November 1991, we have been able to enter information about the activities in the database easily. Although there were some activities related to two or more communities, we were able to know the histories of the activities in each community and the activities of each person rapidly through the database. When dentists are engaged in starting fluoride mouthrinse programs in many communities, the management of information about the activities through a database is a necessity.

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Lundstrom et al. described standard values for young Swedish adults with normal occlusion using soft tissue analysis with a natural head position. The purpose of the present study was to determine the standard reference values of young Japanese adults with normal occlusion using the same method of analysis as Lundstrom. The examiner obtained values for 11 indices (8 horizontal, 2 vertical and 1 horizonal/vertical) from the facial profile photographs of dental school students who had not undergone orthodontic treatment (21 males, 18 females, average age : 23.4 years). The gender and racial differences between the Japanese values and the Swedish values derived from Lundstrom's report were tested for each index using the t-test. The values for some indices were also compared with those of Peck and Peck for American females. Gender differences for 5 indices were observed (No. 1, 2, 3, 6 and 7). The values for these 5 indices in males were 2-10 points higher than those in females. Racial differences in males for 6 indices were observed (No. 2, 3, 6, 7, 8 and 11). Four of the 6 indices in Japanese males (except No. 6 and 11) were 3-6 points higher than those of Swedish males. Racial differences in females for 5 indices were observed (No. 1, 2, 3, 6 and 7). All 5 indices in Japanese females were 4-10 points lower than those for Swedish females. Therefore, it can be concluded that Japanese males have a more prominent nose, upper and lower jaw, chin and a more eminent chin than Japanese females. There was no common Japanese-Swedish characteristic difference between the two in the comparison of males and females. Japanese females have a less prominent nose and less eminent chin than Swedes and Americans. Gender and racial differences should should be considered when using the severity scale of the soft tissue profile for estimating malocclusion.

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The aim of this study was to determine the effects of sucrose and palatinose, which have low cariogenic potential, and the effects of mixtures at different concentrations on the degree of demineralization using a modified enamel demineralization device which we developed. The modified enamel demineralization device was fixed on the buccal surface of the mandibular first molar. Volunteers (n = 8) wore the device for 4 days without brushing to accumulate plaque on the enamel surface. After 4 days, the device was removed and each test solution was directly applied to plaque in vitro. As test solution, 10% palatinose, 9 % palatinose + 1 % sucrose, 8 % palatinose + 2 % sucrose, 7 % palatinose + 3 % sucrose, 5 % palatinose + 5 % sucrose, and 10% sucrose were used. Thin enamel sections (100μm) were evaluated for the degree of demineralization by microradiography. The effect of sucrose on the degree of demineralization was that the more the sucrose in the test solution increased, the more the degree of demineralization increased. The difference between 7 % palatinose + 3 % sucrose, 5 % palatinose + 5 % sucrose, and 10% sucrose was not statistically significant. There were also substantial inter-subject variations among the types of test solutions. To evaluate the cariogenic potential of foods, it may be that there are variations caused by the characteristics of plaque and saliva of volunteers. When selecting subjects, understanding the characteristics of plaque and buffering action of saliva may be important.

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The aim of this study was to investigate the causes of the failure of various types of dental restorations and their longevity. Questionnaires were sent to 10 dental clinics in Japan. When a restoration was replaced or a tooth with a restoration was extracted, each dentist recorded the type of restoration and cause of the failure, and asked the patient about the duration of the restoration. A total of 3,120 failed restorations was analyzed. Secondary caries, loss of restoration, and endodontic involvement were the major causes of failure of overall restorations. Amalgam, composite resin, and inlay restorations were most often replaced because of secondary caries. Cast crowns and banded crowns were most frequently treated again due to endodontic involvement. Loss of restorations was the most frequent problem with resin jacket crowns and metal ceramic crowns. The mean duration of composite resins, inlays, cast crowns, and amalgams was 5.2, 5.4, 7.1 and 7.4 years, respectively. The loss of the restorations shortened the longevity of composite resins, inlays, and prostheses except banded crowns.

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The data concerning newly registered outpatients at the Nippon Dental University Hospital for 1984 were compared with similar data for 1994. The following results were obtained. 1. The number of outpatients registered in 1994 was 4,374, which was 41% greater than the number of patients registered in 1984 (3,097 patients). 2. In both years, patients between 20 and 29 years of age accounted for the highest percentage among all patients registered. The percentage of patients between 30 and 39 years of age did not differ from the percentage of patients between 40 and 49 years of age. 3. There were more females than males. 4. The most frequent complaint of newly registered outpatients was pain. 5. The most frequent dental disease found in the newly registered patients was hard tissue disease such as caries. As the age of patients advanced, periodontal disease or tooth defects tended to increase. 6. The number of patients who complained of abnormalities of the temporomandibular joint was greater in 1994 than in 1984. This tendency was particularly marked in females. 7. The percentage of patients who had had anxiety or fear about receiveing dental treatment was 31% in 1984 versus 29% for 1994. This was the first time this figure was lower than 30%. 8. When we analyzed the incidence of systemic disease in patients presenting with dental disease, gastrointestial disease had the highest incidence, followed by cardiac disase, cardiovascular disease (including hypertension), and then infection.

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We previously reported a study on contaminated water from air-water syringe before treatment. The purpose of this study was to compare the number of bacteria and concentration of endotoxin in water before and after displacement. The number of bacteria was counted using Standard Method Agar (37°C, 48hours). The concentration of endotoxin was measured with ENDOSPECY. Gram stain and VITEK system were used for indentification of bacteria. The results were as follows : The results were as follows: (1) The number of bacteria between pre-and post-displacement of 250ml decreased 93% from 1.36×10^3〜217.0×10^3 to 0〜10.1×10^3CFU/ml. (2) The concentration of endotoxin between pre-and post-displacement of 250ml decreased 88% from 11.5〜472.8 to 0.8〜57.5ng/ml. (3) There was no significant relation between the number of bacteria and the concentration of endotoxin. (4) The decreasing rate of the bacterial counts and the concentration of endotoxin in direct water supply after 250ml displacement were about 10% higher than those in indirect water supply. (5) Bacteria such as Sphingomonas paucimobilis, Flavobacterium sp., Moraxella sp., Corynebacterium sp. were identified from the water samples.

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The aim of this study was to investigate the effects of sample size on the results of statistical tests in epidemiological research. Two kinds of populations were examined. One was made up of two ordinal variables, HU-DBI score and ORI score of young mothers, and the size of the population was 2847. The correlation coefficient of the whole population (ρ) was 0.215 (p<0.001). The HU-DBI questionnaire was an instrument for assessing dental health behavior, and the ORI was an index of oral health status in adults. The other was made up of two interval variables, height and weight of university students, between which the correlation was well known. The size of this population was 2885. The correlation coefficient of the whole population (ρ) was 0.650 (p<0.001). The sample sizes were set at 25, 50, 100, 200, 300, and 400. One hundred random samplings of each sample size were performed in both populations, followed by calculation of correlation coefficients (r) between two variables. Then for each size, the distributions of the 100 correlation coefficients (r) were recorded. The results were as follows. 1. Population with a low ρ 1) When the sample size was 100, 51 values of r were statistically significant. Then the β probability of rejecting the true hypothesis, ρ≠O, was 0.49. 2) When the size was 400, 99 values of r were significant. Then the β probability of rejecting the true hypothesis was 0.01. 2. Population with a high ρ 1) When the size was over 50, all values of r were significant. Then the β probability of rejecting the true hypothesis was zero. These results suggest that the smaller size of a sample taken at random from a population with a low ρ may induce the lower reproductivity of r. Therefore we need to be careful about the size of a sample.

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The purpose of this study was to examine the effect of phosphoric acid-acidified ammonium fluoride solution (900ppmF^-, pH 4.5) on artificial caries lesion formation. It was compared with the effect of acidulated phosphate fluoride (APF) solution. Spacimens of intact human enamel were immersed and stirred in 3 kinds of solution at 37℃ for 1 hour. The three solutions were as follows : (1) phosphric acid-acidified ammonium fluoride solution-NH_4F group, 900ppmF^-, pH 4.5 ; (2) acidulated phosphate fluoride solution-APF group, 900ppmF^-, pH 4.5; (3) cde-ionized water-control group. Artificial caries lesions were formed with demineralizing solution according to Moreno (1974), consisting of 50% synthetic hydroxyapatite saturated lactate buffer (pH 4.5). SEM observation, contact microradiogram (CMR), polarized light microscopy (PLM), and X-ray microbeam diffractometry were performed. In the APF and the NH_4F group, the results were as follows, SEM microphotographs showed many spherical crystals deposited on the surface after flouride treatments. The quantity of spherical crystals was same in the two groups. No crystals were found in the control group. After lesion formation, granular and needle-like deposits were observed on lesion surfaces. The surfaces were smoother than in the control group. It seems that the crystals were formed after immersion. CMR and PLM showed deep demineralization lesions with thin remineralised layer in the control group. In the NH_4F group, the demineralized layers were thinner than control group. In the APF group, the demineralized layers were unclear and thinner than in the NH_4F group. The layer depth was about 20μm in the APF group, about 40μm in the NH_4F group, and about 100μm in the control group. This depth was estimated by doing an EPMA analysis of SEM photographs of cross sections of the lesions. The microbeam X-ray diffraction pattern of the caries lesions showed hydroxyapatite in all groups. In the fluoride group, crystallinity of the lesions was higher than in the control group, and was the same as that of sound enamel. Therefore the cariostatic effect was APF≧NH_4F>control. These findings suggest that enamel immersed in NH_4F solution could be protected from artificial caries formation.

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