In order to establish a more efficient program combining pit and fissure sealant with school-based fluoride mouthrinsing, we designed a program based on a screening method in which pits and fissures with higher caries sensitivity were selected using 4 indices and sealed. These 4 indices were sticky fissures diagnosed as CO, occlusal index, occlusal plaque index (O.P.I), and school grade. The purposes of this study are the evaluation of the usefulness of the program.
The subjects, 1st to 3rd graders, were 465 children in elementary school Y and 175 children in elementary school W. The children lived in two neighboring villages which are similar in socioeconomic environment. They had participated in a school-based fluoride mouthrinsing program (FMR) since nursery school. The FMR consisted of rinsing daily with 0.05% NaF from 4 years of age at in nursery school and rinsing weekly with 0.2% NaF after entrance to elementary school.
The screening method consisted of two steps. In the first step, sticky fissures in the occlusal surfaces, buccal pits, and lingual grooves of all 4 first permanent molars were diagnosed as CO. In the second step, the CO surfaces were evaluated based on occlusal index, O.P.I., and school grade. The surfaces evaluated as being in poor condition by these indices were distinguished as high risk CO (H-CO) from the other CO surfaces estimated as low risk CO (L-CO).
In school Y light-polymerized opaque sealants were applied to H-CO surfaces and L-CO surfaces were left without any application until the next examination 6 months later. In school W both H-CO and L-CO surfaces were left without any application. The progression of caries from the previous level, i.e., sound, sealant applied, H-CO, or L-CO, was compared every 6 months.
In school Y the percentage of surfaces progressing to above C₁ after 6 months was 0.3% in sound, 12.5% in L-CO, and 0% in sealant-applied surfaces. The percentage of complete retention of sealant was 93.1%. The ratio of relative risk estimated was 50.0 in L-CO surfaces against sound surfaces. In school W the percentages of progressing surfaces were 1.6% in sound, 32.9% in H-CO, 17.6% in L-CO, and 30.1% in the total CO surfaces. The ratio of relative risk estimated was 18.8 in the total CO surfaces against sound surfaces and 1.9 in H-CO against L-CO. It was confirmed that CO surfaces, especialy H-CO surfaces selected by this screening method had more risk of dental caries.
The relative risk of sound surfaces in progressing to dental caries was very low. Accordingly it was reasonable that the sealings were applied only to occlusal surfaces selected by the screening method without sealing all the occlusal surfaces. It was concluded that this program of selecting CO surfaces and applying sealant particularly to H-CO surfaces was appropriate for decreasing the cost of sealant application.

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It is necessary to know the utilization and the estimation of fluoride dentifrice in inhabitants in preparation for recommendation and enlightenment on use of fluoride. The aim of this study was to describe the oral health habits (frequency of tooth brushing, use of fluoride dentifrice and reasons for selection of dentifrice) of inhabitants in Niigata City, Sasakami Village and Yahiko Village.
The data were from a survey using questionnaires 3 groups, the Niigata City group, the Sasakami group, and the Yahiko group. The survey was conducted during February-March in 1992. We studied the following subgroups defined by age: 1.5-and 3-year old children, nursery school children, primary school children, junior high school students, high school students, and adults from the Niigata group; and nursery school children, primary school children, junior high school students, and adults from the 2 village groups. The rate of response was 97.6% after excluding incomplete and inconsistent questionnaires. 6003 persons were subjected to analysis.
When these subjects were analyzed, they were classified again into 2 groups, the Niigata group and the villages group, because the oral health did not vary statistically 2 villages.
The results were as follows.
1. Daily toothbrushing was practiced by a majority in all subgroups defined by age. More than 95% in all subgroups over junior high school student brushed their teeth daily.
2. The rate of use of fluoride dentifrice in users of dentifrice did not vary according to group.
3. The rate of use of fluoride dentifrice in uses of dentifrice varied according to subgroups defined by age and tended to decrease with increasing age from over 80% to about 40%.
4. 45.9% of users of dentifrice selected their dentifrice for its medicinal value. 36.8% of them selected their dentifrice for no particular reason.
5. 13.2% of users of fluoride dentifrice and 1.6% of users of non-fluoride dentifrice selected dentifrice for the reason “This dentifrice contains fluoride”.

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This study was designed to revalue topical fluoride treatment time and the time to refrain from rinsing, drinking, or eating following a professional application.
In order to investigate the topical application time, human intact enamel was treated with APF solution (pH3.6, 9, 000ppmF^-) for 0, 1, 2, 3, 4, and 6min. We measured the amount of fluoride penetrating into the enamel, and performed an acid resistance test on experimental groups and a control group. In all fluoride groups, the fluoride concentration in enamel subjects, after treatment with fluoride solution, was greater than in the control group. We found that the fluoride penetrated to the deep interior (200μm). In the 1min group, fluoride penetrating into enamel was 80-90%, and the other fluoride groups were more than the percentage of the 4min group. The acid resistance test showed significant difference between the 2min group and the 3min and the 4 min groups depending on the demineralization time. But we found that the other fluoride groups had the same acid resistance as the 4min group.
To investigate the time for refraining from rinsing, drinking, or eating following a professionally applied topical fluoride treatment, we immersed the enamel treated for 4min with APF into synthetic saliva for 8hr. We assumed that the immersion time was the time for abstaining from rinsing, drinking, or eating, and that stirring represented rinsing, drinking, or eating. Prolonged immersion resulted in greater amounts of fluoride remaining, but even at an immersion time of 0min, the enamel retained more than 2 times the fluoride in the control group in the deep layers.
These findings suggest that the application time can be shortened to 4min, and the time for refraining from rinsing, drinking, or eating following professional application can be shortened to 30min.

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To evaluate the relative cariogenicity of foods, the use of sucose and sorbitol solutions as positive and negative controls has been recomended. The aim of this study was therefore to determine the effect of sugars on the degree of demineralization using an intraoral enamel demineralization device (EDD). The EDD with a thin enamel section (700-800μm) was fixed on the buccal surface of the mandibular first molar. Volunteers (n=6) wore the EDD for 5 days without brushing to stimulate plaque accumulation on the enamel surface and then the mouth was rinsed for 3 minutes with test sugars (10% sucrose and 10% sorbitol solutions), 4 times/day for 10 days. The appliance was removed and the thin enamel sections (100μm) were evaluated for the degree of demineralization by microradiography.
Three cases of demineralization out of 6 were found and in the remaining 3 cases the enamel was intact after rinsing with 10% sucrose solution. After rinsing with 10% sorbitol solution, two cases of demineralization out of 6 were found and in the remaining 4 cases the intact enamel. The effect of sucrose solution on the degree of demineralization was always more progressive than that of sorbitol solution in the intra-subject comparison. The characteristic of the demineralization in situ study was that both intact and demineralized lesion areas were frequently observed in the same section. Two types of lesions, subsurface and surface softening lesions were observed. To evaluate the degree of demineralization, regardless of the type of lesions, demineralized area evaluation based on digital image processing may be useful.

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The purpose of this study was to survey the actual conditions of use of fluoride dentifrices. The subjects were 105 three-year-old children, 413 primary school children of the 3 lower grades, 405 primary school children of the 3 upper grades and 722 students of junior high school. Questionnaires were filled out for each of the four groups.
Almost all the children brushed their teeth every day. The rate of tooth brushing with dentifrice was 94.2% for the students of junior high school, 86.3% for the primary school children of the upper grades, 76.1% for the primary school children of the lower grades and 51.5% for three-year-old children. The rate of use of fluoride dentifrice was the highest for three-year-old children (80.0%), and the lowest was 57.3% for students of junior high school. Regarding the rate of the users who knew their dentifrice contained fluoride, the lowest was 6.1% for the students of junior high school, and the highest was 20.2% for the primary school children of the lower grades. Thus, the users of fluoride dentifrice were little aware that their dentifrice contained fluoride.
It is undoubted fact that the use of fluoride dentifrice is effective in caries prevention. In childhood, when dental caries is frequent more children should use fluoride dentifrices for caries prevention.

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The questionnaire was used to investigate the kinds of dentifrice used in families, the percentage of parents and children using the same dentifrice, and the rate of use of fluoride dentifrice.
The subjects were 105 three-year-old children, 260 primary school children of the lower 3 grades, 231 children of the upper 3 grades, and their parents.
The rate of children using the same dentifrice as their family was 15% for three-year-old children, 33% for primary school children of the lower 3 grades, and 53% for primay school children of the upper 3 grades.
The rate for children using fluoride dentifrice was over 80% when they used their own dentifrice, but the rate dropped to 40-55% when they used the same dentifrice as their family.
Only 6 to 17% of all the subjects and 10 to 20% of the users of fluoride dentifrice were aware that their dentifrice contained fluoride.
To increase the number of users of fluoride dentifrice in the future, we suggest that more dentifrices should contain fluoride and that people should be taught the correct use of fluoride and how to correctly choose a dentifrice.

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A complete soluble protease (Pase-S) possessing Nα-benzoyl-DL-arginine p-nitroanilide (BApNA) hydrolytic activity was isolated from culture supernatants of Porphyromonas gingivalis and purified until homogeneous (43 kDa) on western immunoblotting with anti-Pase-S serum, by a combination of acetone precipitation, gel filtration, high-performance liquid chromatography (HPLC) on Biofine IEC-DEAE, and HPLC on Superose 6. N-Ethylmaleimide, leupeptin, antipain, and p-tosyl-L-lysine chloromethyl ketone strongly inhibited BApNA hydrolytic activity of Pase-S. This enzyme was capable of degrading type IV and denatured type I collagens, but not native type I collagen. It possessed neither Nα-benzoyl-DL-lysine p-nitroanilide hydrolytic activity nor hemagglutinating activity. Our findings suggest that the characteristics of Pase-S are clostripainlike rather than mammalian trypsin-like, and are very similar to those of Pase-B, a membrane bound protease previously described.

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We already reported that there was a positive relationship betweeen caries prevalence in permanent teeth and dental care expenditure (DCE) among young people. In this paper, the influence of fluoride mouth rinsing (FMR) programs on the DCE was analyzed by community. One hundred and eight municipalities out of 112 in Niigata Prefecture were evaluated using the data from 115, 110 subjects 5-19 years of age in 1990. Factor analysis (Multiple regression analysis and Path anlysis), and cost benefit analysis were perfomred. The results showed that the DCE decreased according to the period of practice of FMR, and the differences of DCE between the long-practicing group and the non-practicing group was 19.8% in the group of 5-9 years of age, 48.7% in the group of 10-14 years of age, 34.2% in the group of 15-19 years of age. The strongest factor influencing the DCE was practice of FMR. The number of dentists did not affect it significantly. The amount of DCE which were prevented with FMR was 380.4 million Yen in Niigata Prefecture. Cost benefit ratio was 16.1 when the direct cost of FMR was counted, and 10.1 when the costs for promoting and maintaining the program were counted. We concluded that the benefits of FMR were substantially high in the field of dental care expenditure.

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The optimal fluoride concentration has not been determined because there were few epidemiological studies about dental fluorosis in Japan.
The purpose of this study was to investigate the relationship between the prevalence of enamel mottling and fluoride concentration in drinking water in Japan. We began to look for naturally fluoridated areas in central Japan in 1978. As a result, we found 7 communities in 5 prefectures. There were 26 water supply systems in their communities, and their fluoride concentrations ranged from 0 to 1.4ppm. Subjects for analysis were 1, 081 children aged 10-11 who had lived in the communities from birth.
Dean's Index was used for the classification of dental fluorosis, and non-fluoride enamel mottling was classified in the same way as Dean's Index, too.
A significant positive correlation (r=0.485, p<0.05) was found between the prevalence of dental fluorosis (very mild or mild types) and fluoride concentration and a negative correlation (r=-0.429, p<0.05) was found between the prevalence of non-fluoride enamel mottling and fluoride concentration. There was no relationship (r=-0.129, ns) between the prevalence of all enamel mottling and fluoride concentration. We could not find moderate or severe types of dental fluorosis in these investigations and CFI ranged from 0.04 to 0.30.
We concluded that there was no problem concerning dental fluorosis from 0 to 1.4ppm fluoride concentration in the drinking water in these communities. We believe that these findings make up for the insufficiency of the epidemiological study of dental fluorosis in Japan.

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It is important to understand the fluoride ingestion in daily life when a community is planning to commence the caries prevention program using fluoride. In this study, samples were collected from 14 groups of the 65 food items availadle at a super-market in Fukuoka.
The foods were measured 8 times ot determine the fluoride content with a fluoride ion-specific electrode with microdiffusion of ashed samples.
The fluoride contein in foods was as follows: grains, range 0.19-6.04μg/g, average 2.35μg/g in rice, 0.12μg/g in wheat; seeds and nuts, 0.12; potatoes, 0.01-0.02, 0.02; beans, 0.42-41.75, 11.46; fruits, n. d. -0.02, 0.01; vegetables, n. d. -0.94, 0.10; mushrooms, 0.01-0.75, 0.26; seaweeds, 0.06-0.58, 0.32; beverages, 0.17-2.99, 1.13; fishes and seafoods, n. d. -2.87, 0.73; meats, 0.04-0.21, 0.10; eggs, n. d., 0.00; dairy products, 0.35-1.52, 0.93.
The average daily dietary fluoride intake by adults was estimated from the values obtains in this study for each group of foods and intake of the foods given by the Nati onal Nutrition Research Survey. The fluoride intake per person was estimated at 1.44mg/day in all Japan and 1.42mg/day in Northern Kyushu.

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