Over the period from April 1985 to March 1986 we studied of 1019 pregnant women living in Edogawa Ward. Tokyo, concerning their awareness of the mouth and gingivae. The age of the pregnant women peaked at 26, showing normal age distribution. The number of months pregnant was highest at 7 months, or 32.0%.
85.6% of the pregnant momen replied that they could clean their teeth exactly as they could before becoming pregnant. 15.2% said that they felt nausea when cleaning their teeth, many of whom were in the early stage of pregnacy.
63.3% answered that their gingivae tended to bleed after becoming pregnant, many of them being the early stage of pregnancy.
53.9% ate more between meals, while a change in the sense of taste was observed in 46.8%.
57.8% of the women who had already experienced childbirth replied that the state of their teeth and gingivae was different compared to the time of their first pregnancy.
In a comparison between the state of gingivae and the reply to each question, it was found that were in fact aware of such conditions as bleeding from the gingivae, feeling nausea when cleaning their teeth, increased eating between meals, and change in the sense of taste.

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This study was carried out to determine the fluoride distribution in cementum of rat molars under varying fluoride administration. Four groups of Wistar rats received water containing 0, 25, 50 and 100 ppm fluoride respectively for 10 weeks. Cementum specimens were removed from the distal root of the first molars. Fluoride distribution in each specimen was analysed from the surface to cementum-dentine junction using an abrasive micro-sampling technique.
The following results were obtained;
1) The fluoride distribution was higher at or near the surface and decreased towards the interior in both control and experimental groups.
2) The concentration throughout the tissue increased with fluoride intake.
3) The distribution patterns were roughly the same in right and left teeth of the subject.
4) It was considered that the rat molar cementum could be used as an experimental model for research on human cementum.

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[in Japanese]

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This study demonstrated the chemical stability of remineralized enamel under various test conditions. Lesions were produced on bovine enamel slabs (N=20; 3×5mm) by a 2-day immersion in 0.01mol/l lactic acid buffer containing 3.0mmol/l Ca, 1.8mmol/l P, 1% CMC, adjusted to pH 4.0 and 37°C. The remineralizing solution contained the same amount of Ca, P, and CMC plus 150mmol/l NaCl and 3 ppm F, and was adjusted to pH 7.0 and 37°C. All slabs were exposed to this unstirred solution which was changed every two days during the 10-day remineralizing period. Each five remineralized slabs were divided into four groups. Group A (the control group) received no further treatment. The other three groups were exposed for 24 hours to either the intraoral environment (Group B), a 1.0mol/l KOH solution (Group C), or a 0.01mol/l lactic acid buffer (Group D).
Typical microradiographic pictures assessed by quantitative microradiography showed no clear difference in the radiographic density of the remineralized lesions in relation to the three test conditions. The range between maximum and minimum of mineral contents in vol % of five measurements at a certain depth were within 10%. Remineralization of the lesion appeared to be complete after the 10-day exposure. The result of the subsequent 1mol/l HClO₄ treatment showed a radiopaque zone, concurrent with remineralized enamel, indicative of acid resistance. The lack of appreciable mineral change from enamel with any of the above conditions indicated a chemical stability of mineral in the remineralized enamel.

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[in Japanese]

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The progression of incipient caries in the pits & fissures of permanent teeth was observed. The subject teeth were 375 cases of [C₀] and 250 cases of [C₁], in 477 primary school children who participated in a fluoride mouth rinsing program (0.05% NaF, once a day, 5 times a week in total). Caries examinations were made every 6 months for 2 years, without X-rays, and each subject was in charge of the same examiner. We found how to judge clinical caries which needs immediate treatment, and other useful information for caries control programs.
The percentage of incipient caries [C₀] which changed into caries [C₁] or [C₂] after 24 months was 51.1% in total, of which 2/3 was caries [C₁]. The percentage of caries [C₀] which disappeared after 6-24 months was about 15%. Besides, no incipient caries [C₀] which progressed to [C₃] could be found in any of the children. The percentage of incipient caries [C₁] which progressed to caries [C₂] after 24 months was 57.4%. There was only one case that progressed to caries [C₃] after 12 months.
Comparing the progression rate, the maintenance rate and the reversion rate, significant differences were recognized between the lower and higher grades. The progression rate of caries [C₀] in the 1st grade group was 69.0% and in the 5th grade group 25.3% after 12 months. It was very high in lower grade groups but low in the higher grade groups. A similar tendency was seen in the progression rate of caries [C₁]. The rate in the 1st grade group was 80.0% and in the 5th grade group 19.4%. On the other hand, the maintenance rate and the reversion rate were high in the higher grade groups. The cases of unchanged or reverted caries occupied about 80% in the 4th and 5th groups. The cumulative progression rate was also studied. Similar differences were recognized between the lower and higher grades. The cumulative progression rate increased most rapidly in the 1st grade group, but more slowly in the higher grade groups.
The concreate methods of caries control to avoid excessive treatment was proposed with fluoride mouth rinsing program. In cases of [C₀], instead of treatment, the preventive action until the next examination was recommended. On the other hand, in cases of [C₁], the treatment or reexamination were recommended. Immediate filling treatment should be given to children in the 1st, 2nd and 3rd grades. For children in the 4th, 5th and 6th grades, the preventive action should be taken without treatment, until the cases of caries [C₁] progress to caries [C₂].

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For the evaluation of physical growth in children, percentile curves have been widely accepted as a health index not only by health workers but also by the Maternal and Child Health Handbook for personal use.
In this report, for the application of evaluation by percentile levels to the field of dental health, percentile curves and pecrentage curves of persons with decayed and filled deciduous teeth (df teeth) and missing permanent teeth were determined and their significance was examined.
Percentile and percentage curves of df teeth were estimated from the cumulative frequency distribution of 5670 children aged from 1 year to 6 years and 8 months, surveyed in 1984. The curves of each age stage showed clearly the relative distribution of deciduous carious teeth in this population.
Percentile and percentage curves of missing permanent teeth were also estimated from 11725 subjects aged 10-79 years, reported by the National Survey of Dental Disease (Japan, 1981). The profile of the curves of missing teeth in permanent dentition showed adequatly the present status and the trends of aging in dental health.
These figures will be useful and effective in evaluating the dental health of individuals and communities level for dental health education and guidance.
Further studies are needed to develop the application and utilization of these figures for various aspects of dental health education.

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The effect of carboxymethylcellulose (CMC) on enamel remineralization was investigated in in vitro. CMC is a component of artificial saliva substitutes and may be considered as a model molecule for the salivary mucins. Human dental enamel slabs (N=60) were demineralized for 12 hours by immersion in a demineralizing solution containing 0.1M lactic acid, 3.0mM Ca, 1.8mM P, and 1% CMC at pH 4.5. After demineralization, the enamel slabs were immersed in four groups of remineralizing solutions for 10days (20ml/slab), which contained 3.0mM Ca, 1.8mM P, and 150mM NaCl at pH7.0, with and without 1% CMC and 3ppm fluoride, that is, (1) 0% CMC/0ppm F (C0F0), (2) 1% CMC/0ppm F (C1F0), (3) 0% CMC/3ppm F (C0F3), and (4) 1 % CMC/3ppm F (C1F3). After remineralization, the degree of remineralization were evaluated by chemical analysis for Ca amount, Ca/P ratio, and fluoride uptake, and by microradiography using calculated mineral vol%. The remineralized enamel slabs were treated with 1.0N HClO₄ solution to evaluate the acid resistance and also the mineral vol% was reevaluated by microradiography. The following results were obtained.
1) The fluoride uptake in group C1F3 was about two times higher than that of group C0F3 for the first to fourth layers (p<0.05). 2) According to the microradiography evaluation of group C1F0, the lowest mineral vol% was evident. Groups C0F0, C0F3, and C1F3 were obviously remineralized, but the mineral vol% of group C0F3 was lower than that of groups C0F0 and C1F3. 3) A radiopaque zone, indicating acid resistance, was not found in group C1F0, but the other three groups showed acid resistant zones. The microradiographic characteristics of the acid resistant zone in groups C0F3 and C1F3 were uniform. This zone was formed through the remineralized area, particularly at the surface and bottom layer of the remineralized area. In group C0F0, however, such uniformity was not found. 4) The Ca amount and Ca/P ratio were not sufficient to evaluate the degree of remineralization.
These results suggest that not only the CMC molecule, which is relatively large (50, 000-12, 000), inhibits remineralization without fluoride ions, but also, that the CMC molecule promotes fluoride uptake and the degree of remineralization with fluoride ions.

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The purpose of this study was to compare the caries prevalence and incidence between 6-year-old lifelong residents in a natural fluoride area (0.74-1.10ppm F: NF group) and participants in school-based fluoride mouthrinsing (FR group) or usage of SnF₂ dentifrice (FD group). The FR group rinsed daily with 0.05% NaF solution for 3.5 years and the FD group used 0.41% SnF₂dentifrice for 3 years beginning at the age of six.
Mean DMFT in the NF group (n=58) from the age of 6 to 9 was significantly lower (p<0.05, p<0.01) than that of both the FR (n=78) and the FD group (n=73) at all of the ages examined. Only 1-year mean DMFT increments from the age of 6 to 7 in the NF group (0.24±0.67) were significantly different (p<0.01) from the FR group (0.67±0.98) and the FD group (0.71±0.89). No statistical differences of mean DMFT increments, however, were found between any pairs of study groups after 2 or 3 years from the baseline. Incremental DMFT rates on first molars in the NF group were significantly lower (p<0.05, p<0.001) than those in the FR or FD group both after 1 and after 2 years.
The results of the present study demonstrate that lifelong residents in a natural fluoride area experienced significantly fewer caries than those who received topical fluoride application. However, the differences of caries increments between the FW group and the FR or FD groups diminished with the passage of time.

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Relations between regional differences in dental caries prevalence in 3-year-old Japanese children and some community characteristics possibly related to the dental health status were studied using multivariate analysis. A total of 31 community socio-economical, cultural, and health indices of each prefecture were employed to qualify the prefectural characteristics by means of factor and cluster analysis. Five common factors were closely related to prefectural differences and 47 prefectures were divided into three areas. One of these areas connected with high caries prevalence among 3-year-olds was the rural area, which was associated with specific indices such as gross agricultural products and ratio of persons employed in the primary industry. Our investigation clearly showed that high caries prevalence among 3-year-old Japanese children is coincident with ruralization (multiple regression coefficient R=0.849, p<0.01).

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We conducted a program for preventing gingival inflammation for 3 years in a junior high school in Niigata Prefecture, Japan. The program consisted mainly of instruction in oral prophylaxis and oral health education.
The purpose of this study was to evaluate the effects of the program.
The results were as follows;
1. The prevalence of gingival inflammation in the students was about 70%.
2. At the baseline, the average number of segments with gingival inflammation in 3rd grade students was greater than in 1st and 2nd grade students, and the differences were statistically significant (p<0.05).
3. This study indicated that the program for preventing gingival inflammation was very effective, and the maximum value of the reduction rate was 55.4%. Especially effective was the fact that we screened out the serious cases and instructed them individually.
4. The degree of gingival inflammation in the students decreased for about 1 year. But after 1 year, the degree was reversed slightly. However, the reduction rate between baseline and after 2.5 years was still high and about a 40% effect remained.
5. A Highly statistical relationship between plaque and gingival inflammation was found both at the baseline and after 1 year. The partial correlation coefficients were 0.37 (p<0.001) and 0.18 (p<0.001).
6. Instruction for improving individual toothbrushing habits helped the students to form desirable habits for a short period, but it was difficult to maintain these favorable habits for long periods.

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