[in Japanese]

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For evaluating the severity of periodontal disease in deciduous dentition, we used to examine the mesial parts of the gingival margins of all the teeth in the mouth. This method, however, takes too much time for application to mass screening. The purpose of this study was, therefore, to design a simplified method.
Materials used were dental health examination data of periodontal disease in the Miyako Islands in Okinawa, obtained from 667 cases of three-year-old children, and 143 cases of one-and-a-half-year-old children. Principal component analysis and multiple regression analysis were applied to these data to select the standard teeth, and to proove the appropriateness of the teeth selected. Comparing the mean scores of periodontal disease of each tooth, high scores were observed at the most posterior teeth in the maxilla. As the result of principal component analysis, the teeth were divided into three groups, i. e. maxillary anterior teeth, mandibular anterior teeth, and maxillary and mandibular posterior teeth in three-year-old children. On the basis of these results each of the most posterior teeth in the maxilla, the maxillary lateral deciduous incisors, and the mandibular deciduous incisors were selected as standard teeth, because no dominant difference was observed between the teeth on the right and left sides. Multiple regression analysis showed that this model predicted means of the periodontal score of all the teeth very well, and adding other variables of teeth did not improve the prediction much. The correlation coefficient between the mean of these teeth and that of Periodontal score was very high (r=0.89-0.90). Almost the same results were obtained in one-and-half-year-old children, in which the unerupted maxillary 2nd deciduous molar was replaced by the most posterior teeth in the maxilla (r=0.87-0.91).

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[in Japanese]

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After approximately 150 subcultures in the skimmed milk medium, we found a characteristically outstanding variant, designated as Streptococcus sp. 6480, from the parent strain Streptococcus NC 49, isolated previously from human dental plaque, lacking the ability to produce extra-cellular polysaccharides from sucrose.
Streptococcus sp. 6480 failed to produce acid from mannitol and sorbitol, whereas NC 49 as well as S. mutans produced it. The variant cells agglutinated slightly in anti-S. mutans serum but strongly in anti-Streptococcus sp. ATCC 15910 serum, though NC 49 cells agglutinated positively in anti-S. mutans NCTC 10449 serum.
Streptococcus sp. 6480 as well as its parent strain was not cariogenic in hamsters. When applied into the oral cavity of hamsters which were infected with S. mutans NCTC 10449, Streptococcus sp. 6480 significantly inhibited the induction of dental caries by S. mutans.

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To study the relationship of different life-styles to oral health in adults, persons living in fishing and farming villages of Shimane Prefecture, Japan, were examined for subjective symptoms, number of healthy teeth, number of missing teeth, tooth-brushing habits, and periodontal disease. The data were analyzed and compared epidemiologically between fishing and farming villages.
In univariate analyses, the mean number of missing teeth per person was larger, and tooth-brushing habits were more common, in fishing villages than in farming villages. The proportion of persons with subjective symptoms in each village was similar.
In analyses by Hayashi's Quantification Scaling Type 2 Method, the rate of life-style discrimination between the villages was high in both sexes. The number of healthy teeth was most closely related with the discrimination rate. The proportion of persons with subjective symptoms and the prevalence of tooth brushing habits were almost not related. The incidence of periodontal disease was related with the discrimination rate only in females.

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In a previous paper we showed that Bacteroides gingivalis produces SH-dependent collagenolytic enzyme and that the activity is inhibited by the extract of soybean meal. The purpose of this study is to describe the isolation, partial purification, and characterization of this inhibitory substance.
Dried soybeans were pulverized in a coffee mill to pass a 60 mesh sieve and suspended at a 2% concentration in 10mM Tris-HCl buffer, pH 7.4, containing 0.1M NaCl. The suspension was centrifuged at 10, 000×g and the supernatant was used as crude soybean extract. The inhibitory substance in the crude extract was further purified by DEAE-cellulose column chromatography and gel filtration on Sepharose CL-6B, and the active fraction for the inhibition of the collagenolytic enzyme from B. gingivalis was collected, concentrated, and named soybean collagenase inhibitor (SCI). The crude extract contained soybean trypsin inhibitor (STI), and inhibited the trypsin and collagenolytic enzyme of B. gingivalis, but no inhibition was observed for Clostridium histolyticum enzyme and the protease of B. gingivalis. However, the SCI was successfully separated from STI by these purification procedures. The molecular weight of SCI estimated by gel filtration was approximately 700K dalton. STI was inactivated by heat treatment in an autoclave for 20min at 15lbs/in², but SCI was stable for the same treatment. This substance was very effective in protecting human gingival fibroblast cells (HGF) from cytopathogenicity of the collagenolytic enzyme of B. gingivalis. These results suggest that this collagenase inhitor maintains normal turnover of gingival cells and prevents the developement of periodontal disease.

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In order to demonstrate that oral mycoplasmas adhere to oral epithelial cells, attempts were made to isolate mycoplasmas from the cells. The cells from 121 subjects (60 males and 61 females, ranging in age from 0 to 81 years) were sampled from buccal mucosa and gingiva with sterile swabs; suspended in liquid medium for the growth of mycoplasmas; washed 3 times without changing a centrifuge tube for each washing in 3mlof the liquid medium (Experiment I) or with changing in 5mlof the medium (Experiment II); suspended in the medium; and incubated at 37°C. The cells were sedimented by centrifugation at 90×g for 5min. In Experiment I, mycoplasmas were isolated from buccal cells of 15 (71%) of 21 subjects and from gingival cells of 14 (67%); and from buccal cells of 34 (42%) of 81 subjects in Experiment II. Of 268 strains isolated from buccal cells, 217 (81%) and 51 (19%) were identified withMycoplasma salivariumandMycoplasma orale, respectively; and 143 (76%) of 188 strains from gingival cells and 45 (24%) with the former and the latter. Thus, oral mycoplasmas were demonstrated to adhere to oral epithelial cells.
Therefore, experiments were carried out to know whether or notM. salivariumadheres to buccal cellsin vitro. An enzyme-linked immunosorbent assay was applied to detect the organisms quantitatively. The organism was shown to have adhered in situ to the buccal cells of 17 (89%) of 19 subjects, when the cells were sampled, and to adhere to these cells slightly or not to adhere entirely, when they were incubated with the organism. On the other hand, the organism was not detected from the cells of 2 subjects, and was shown to adhere to these cells.

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The fluoride uptake and remineralization of partially demineralized enamel after various fluoride applications for 10 days were investigated in vivo. The fluoride applications involved use of MFP dentifrice twice a day; 100ppmF mouthrinse once a day; acidulated phosphate fluoride (APF) applied only once; or no treatment (control). The degree of remineralization was evaluated by mineral vol% using microradiography. The following results were obtained.
1) The fluoride uptake from dentifrice and mouthrinse were about 1.2-1.5 and 2-3 times higher than that of the controls, respectively. But statistically significant differences were not found between these three groups. The fluoride uptake from APF treatment was about 14-15 times higher than that of the controls, and statistically significantly higher than the other three groups from the first to the fifth layer.
2) The remineralization was evident in all four groups except in one control case. The degree of remineralization in the dentifrice was nearly equal to that in the remineralized controls. Remineralization with the rinse was higher in the first and second layer (about 10-20μm depth) than that with the control and the dentifrice. The degree of remineralization for APF was the highest and the remineralization was evident from the surface to the bottom of the lesion area.

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The purpose of this study was to investigate the effect of topical fluoride application and fluoride mouth rinsing introduced into school dental health programs. Especially, the cariostatic effects of each tooth DMFT rate in erupted period classified by school grade were evaluated. Another study was performed to survey the prolonged prophylactic effect of these fluoride programs in primary school. For the purpose of this study, cohort analysis was carried out on the senior high school students who joined these programs for 6 years in their primary school years. Topical fluoride application was given once a year using an acidulated phosphate fluoride solution (0.9% of F, pH 3.6), and fluoride mouthrinsing was practiced 5 times a week after every school lunch with a phospholic acid-acidified NaF solution (0.05% of F, pH 5.0) for 6 years.
A precise oral examination for dental caries was carried out in April or May of each primary school year and at March graduation and 31 months after graduation.
A higher cariostatic effect was obtained in the preventive group (experimental group) compared with the control group, and early erupted teeth tended to show a higher DMFT rate in each kind of tooth and each erupted school grade. The results 31 months after the final fluoride application program showed the durability of cariostatic effect in upper incisers, both premolars and first molars, but not in the second molar.
From these findings, it is concluded that evaluation of cariostatic effect of fluoride application by means of DMFT rate for each kind of tooth and each school grade is a useful method, and that the school dental health program combined with fluoride application practised in primary school also produces prolonged cariostatic effect in many kind of teeth after 31 months in senior high school.

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[in Japanese]

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The purpose of this study was to determine total fluoride in powdered milk for babies. We determined fluoride in the diffusates of ashed samples using an ion-specific electrode.
The 74 blanks observed in this study contained 0.10±0.10μg of fluoride (M±SD). Mean recovery for analysis determined by adding 0.1-1.0μg of fluoride was 94%. Coefficients of variance in recovery test and in repeated analysis ranged from 5 to 13%, 4 to 8%, respectively.
The total fluoride content of powdered milk ranged from 0.22 to 0.40ppm.

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