The bacteriocinogenic and highly adhesive strains were screened in laboratory stock strains of Streptececcus mutans for isolation of low -cariogenicity mutants which could act against wild strains of S. mutans All tested strains of S. mutans inhibited the growth of Streptececcus mutans and Streptececcus faecalis. In particular, S. mutans P2, C67-1, B14, and OMZ 175 showed bacteriocin activity against many tested strains of S. mutans. Of these four strains, S. mutans B14 could adhere to the smooth surface of glass and establish itself in the oral cavity of hamsters to the same degree as a highly cariogenic strain S. mutans K1-R.
S. mutans B14 produced bacteriocin on Todd-Hewitt and trypticase soy-yeast extract agar plate, but not on brain heart infusion or trypticase soy agar plate. In broth culture, stabilizing agents like agar, yeast extract, and starch had only a slight effect on the production of bacteriocin.
The bacteriocin produced by S. mutans B14 was heatstable and sensitive to protease, but insensitive to DNase, RNase, and catalase. The molecular weight of the bacteriocin was estimated at 1, 000-3, 500 by dialysis. It was assumed that molecules of bacteriocin aggregated with each other or with the materials of the culture medium because of the dialysis and gel filtration.

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A school dental health program was carried out for 4-8 year-old children in an elementary school and kindergarten in Horieminami district in Naruto City for two years, 1981 to 1983. The program mainly included topical application of acidulated phosphate fluoride, daily tooth brushing after lunch, and dental health education. First molars and permanent incisors were examined, and the effect of the program on prevention of dental caries was evaluated. Children in another school in Horie-kita district were also surveyed as a control.
When the program started, the caries prevalence rate and the average DMFT index of firstgrade school children in Horie-minami were significantly higher than those of the same grade of children in Horie-kita. However, children in both districts showed no difference in their oral status after the two-year program. The oral health status of children in Horie-minami had improved to the degree of that in Horie-kita.
The second-year children of the kindergarten in Horie-minami had significantly more erupted first molars than those in Horie-kita at the beginning of the program, and they developed many more caries lesions in the first molars during the program. This indicated that it was difficult to prevent caries in first molars which had erupted earlier and prematurely.
No significant correlation was observed in any teeth between the amount of dental plaque accumulated and the caries rate.
The number of children who brushed more than twice a day increased significantly during the program in Horie-minami.
However, the following problems remain to be solved: 1) the restration rate was much lower in Horie-minami children; and 2) children in the Horie district, in general, had more decayed teeth than the average Japanese child.

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This study was attempted to establish normal levels of ethanol (EtOH) and acetone (ACE) in mixed saliva without ingestion of alcoholic drinks, and to examine the correlation among those levels in mixed and parotid saliva, whole blood, and plasma. An attempt was also made to confirm the production of ethanol in the oral cavity by determining its production in vitro when saccharides (Saccharose and Glucose) were added to saliva.
The results were as follows.
1. The effect of sodium nitrite on ethanol levels in mixed saliva was observed. Filtration of mixed saliva prevented oxidation of ethanol and permitted longer periods of sample storage.
2. Ethanol levels in mixed saliva of 204 subjects showed a normal logarithmic pattern of distribution. The geometric mean was 1.07μg/ml (SD_G; 2.26) and the arithmetic mean was 1.41±0.97μg/ml.
3. Acetone levels in mixed saliva of 164 subjects showed a normal logarithmic pattern of distribution. The geometric mean was 0.25μg/ml (SD_G; 1.66) and the arithmetic mean was 0.29±0.20μg/ml
4. The correlation among ethanol and acetone levels in mixed and parotid saliva, whole blood and plasma was as follows.
1) The correlation between ethanol and acetone levels in parotid saliva and plasma was significant. (EtOH: r=0.72, ACE: r=0.76)
Ethanol levels in parotid saliva and whole blood were not correlated.
The correlation between acetone levels in parotid saliva and whole blood was significant. (r=0.78)
2) Ethanol levels in mixed saliva and blood were not correlated.
3) A good correlation was observed between acetone levels in mixed and parotid saliva. (r=0.84)
The correlation between acetone levels in mixed saliva and wohle blood (plasma) was significant. r=0.52 (r=0.51)
5. The production of ethanol in vitro was confirmed by the addition of saccharides to mixed saliva. However its production was not observed in parotid saliva, and in filtered mixed saliva, and in mixed saliva only when sodium nitrite was added to that.
In conclusion, it was obvious that ethanol levels in mixed saliva were affected by conditions in the oral cavity. But it seemed that acetone levels in mixed saliva did not change much because there was no relation to conditions in the oral cavity, and that acetone levels were related to age.

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The purpose of this study aimed at analyzing factors related to mothers' responses on participation with their children in a program of school-based topical fluoride application. To obtain information, a questionnaire was sent to 395 mothers whose first-born children were in the 3rd or higher grades of elementary school. These children were eligible to participate in the program of school-based topical fluoride application during the 3rd or 4th grade with parental consent.
Three hundred and eighty-two mothers (97% of the original sample) knew about the program. Of these, 317 mothrs (83%) had their children participate in the program, and the rest 65 mothers (17%) did not apply. This distribution did not vary significantly with degree of terminal education, time and medium of initial awareness of the program, or other factors.
The results of this study suggest that difference of education and past history of participation in the topical fluoride application exerted little influence on the decision to join the program. Therefore, a positive attitude among professionals is necessary to generate consensus among parents in school dental health programs.

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In order to clinically evaluate salivary duffer effect, a study was made of the resulting pH (the buffer pH) of the saliva when a specified volume of 0.1 N lactic acid was added to the sample according to the method of Dreizen et al. Attempts were also made to investigate factors which could affect the buffer capacity.
Whole mouth saliva samples were collected during the so called resting state and during the mastication of a bolus of sugarless chewing gum from 54 children 4-9 years old and 135 dental students between the ages of 22 and 27 years.
The buffer capacity was characteristic for each individual when 2.0 ml of whole saliva was titrated against 0.3 ml lactic acid. The relationship between the present buffer pH and the results of Dreizen et al. showed good agreement (r=0.92). The buffer capacity (buffer pH) was positively correlated with salivary flow rate in stimulated whole saliva (r=0.59, p<0.001), but not in resting saliva. In resting saliva, however, partial correlation analysis showed that the buffer capacity and the flow rate negatively correlated if the saliva pH factor was fixed. The mean buffer pH for the stimulated saliva of children was pH 5.41 (SD±0.51), and that of adults pH 5.72 (SD±0.50), the latter being significantly higher than the former. The difference in the mean buffer pH value was not significant before and after shaking saliva samples for a minute. 3-min aerat ion of the saliva sample after the addition of the acids caused a slight increase in buffer pH value with statistical significance. The buffer pH values of 5-min saliva samples collected during a continuous 30-min stimulation seemed to change mainly depending on the flow rate and to reach an apparent steady state within 15-20 min. Significant difference in mean salivary buffer measured at an identical time for three consecutive days was not found.
Finally, significant negative correlation between the buffer capacity and the prevalence of caries was found in both children and adults.

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We have developed a rapid caries activity test (Resazurin Disc test, RD test) based on the specific color reaction of resazurin. In a previous paper (1984), we investigated the relationship between the RD test scores and caries prevalence for a clinical trial. In this report, the possibility of caries prediction by the RD test score was studied. A clinical trial was carried out on 33 kindergarden children aged 4 years.
Relationship between the RD test scores and caries increment on initially sound surfaces after 6 and 12 months (Δdf-s) was assessed. Caries increment (Δdf-s) in the high score group (_??_·_??_) was greater than in the low score group (-·+). This tendency was more notable after 12 months.
We also recognized the necessity of taking into account the age of the subjects, the type of teeth, and the specific tooth surfaces in the case of estimation of caries prediction.

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A series of experiments were carried out to determine the fluoride content of human milk and dry milk (for formula feeding), day-today or time-course variations of the amount of fluoride contained in human milk, and fluoride excretion in human milk through ingestion of fluoride. Fluoride determination was done by microdiffusion technique with hexamethyldisiloxane and by pH/mV meter (Orion 801) with a fluoride sensitive electrode (Orion 96-09).
The amount of fluoride contained in human milk was 3-7 ng/ml, which was mostly separated as compounds with a molecular weight under 500 through the ultrafiltration technique (Amicon, Diaflo membrane UM 05). Fluoride excretion in the human milk seemed to reflect fluoride ingestion to some extent, because it was increased 2 to 4 times by the ingestion of 5 or 10 mg of fluoride.
On the other hand, the fluoride content in several kinds of dry milk was 50-80 ng/ml, when they were reconstituted with distilled water. In actual use, however, their fluoride content could be even higher because of the addition of fluoride from drinking water. Therefore, the fluoride intake by nursing infants from human milk is much lower than formula milk.

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Good oral prophylaxis is believed to improve tooth mobility in periodontal disease. The purpose of this study was to clarify what kind of mobile teeth are improved by oral prophylaxis. One hundred and fourteen patients were selected. They received professional oral prophylaxis and toothbrushing instruction in cleaning the interdental areas every two weeks. Tooth mobility was scored at 0 weeks, 4 weeks and 8 weeks. Fifty per cent of the mobile teeth were improved after 4 weeks and 56% after 8 weeks. No relation was observed between the improvement rate of the mobile teeth and host factors such as sex, age, the severity of the mobility, or tooth shape. The teeth in the right mandible showed a significantly lower rate of improvement than the others for 8 weeks. The left mandibular first molar was the best improved tooth and the right maxillary first premolar was the worst.

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This report describes the concentration of trace metals in two hundred permanent teeth, free of restorations and dental caries, which were 200 samples collected from 13 districts of Japan. The concentrations of manganese, cadmium, and calcium in human teeth were determined by atomic absorption spectrophotometry.
The results were as follows:
1) The mean values of metal concentrations in 200 teeth were 7.88μg Mn/g, 1.22μg Cd/g and 236.4 mg Ca/g on a basis of dry weight (Table 6).
2) The distributions of Mn and Cd in teeth exhibited logarithmic-normal patterns, but that of Ca showed normal distributions pattern (Fig. 3, Fig. 4, Fig. 5).
3) No significant difference was found in concentrations of Mn and Cd between males and females. (Table 6).
4) The concentrations of Cd in teeth showed wide variation according to geographic locality: seaside areas (1.74±1.54μg/g) > mountainous areas (1.00±0.71μg/g) > metropolitan areas; Tokyo (0.64±0.43μg/g). However, the concentrations of Mn were higher the teeth above 50 years of age than in teeth below 49 years of age at the 99 percent level of significance (Table 8, Table 7).
5) The concentrations of Mn in teeth did not show wide variation according to geographic locality (Table 8).
6) Significant correlations were observed between the Cd and Ca contents (r=0.35, p<0.001). More significant correlations in teeth from the seaside area were observed between the Cd and Ca contents (r=0.49, p<0.001) (Fig. 6, Fig. 10).

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The Survey of Dental Diseases, a nationwide survey of dental diseases in Japan, has been performed five times, i. e., every six years from 1952 to 1981, by the Ministry of Health and Welfare. Cohort analysis is a useful analytical method for such a set of time-series survey data. In these survey reports, the data are arranged by every five years of age, while the intervals of the survey have been every six years, so that it is difficult to apply standard cohort table analysis.
In the present study, an isometric line map method and a Bayesian cohort analysis method are applied to the data on the lower first molar DMFT obtained from the survey reports. The isometric line map reveals that the cohorts born during World War II have a lower DMFT than the cohorts of the prewar and postwar periods. Using the Bayesian cohort model, age, period, and cohort effects can be separated, and the results clearly show a reduction of dental caries in the youngest cohort. The cohort born in 1962-66 have the highest cohort effect and the DMFT is reduced after this generation. The Bayesian cohort analysis also shows that the age effect on the DMFT in females increases gradually from adolescence to the twenties, whereas in males there is almost no change in that effect during that period of life.

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In vivo enamel solubility rate in a single adult was studied by measuring the dissolved calcium from the labial or buccal enamel surface after application of a cellulose acetate membrane (φ: 3mm) with a soidum acetate- hydrochloric acid buffer (1.4 M acetic acid, pH 2.3) 2μl. The effect of the acquired pellicle on the enamel solubility rate was also studied by comparing the values before polishing, just after polishing and two hrs after polishing. The following results were obtained.
1) The enamel solubility rate pattern in the upper and lower dentition was exactly the same as that of two years ago; the value was highest in the molars and lowest in the incisors. The premolars and the canines showed a value intermediate between the molar and the incisor.
2) Although the enamel solubility rate was significantly higher for the polished teeth, the pattern showed little changs.
3) A relationship in enamel solubility rate value between right homogous teeth was found whether teeth were polished or not.
4) Enamel solubility rate just after polishing decreased when the teeth were exposed to the oral environment for two hrs, probably because of the acquired pellicle.
It was concluded that the enamel solubility rate pattern in the upper and lower dentition is little influenced by tooth surface pollshing, but solubility is rate reduced by the acquired pellicle.

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