リン定量によるほうろう質生検法を応用した歯質耐酸性の分布ならびに齲蝕罹患との関係(歯質耐酸性測定法シリーズ-4-)
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In order to figure out quantitatively the susceptibility to caries common to all types of teeth, which is indicated by the factor"r"in the epidemiological principles of dental caries attack proposed by Takeuchi, it is necessary to elucidate the distribution of the acid resistance of the surface enamel of each type of tooth. In this study, the Kameoka community was chosen for the investigation on the basis of its representing the average condition of Japan as regards socio-economical situation for epidemiological surveys. Furthermore, the influence of fluoride concentration in the drinking water on caries incidence in this area was negligible, and the annual sugar consumption per person in Japan was. approximately 20kg at the time of this investigation. Subjects for this study were divided into two groups. Group"A"consisted of the children of Kameoka Primary School who. entered the first grade in 1965, and Group"B"was the children of Kameoka and Oi Primary Schools who entered the fourth grade in 1965 (Table 1 and Fig. 1).<BR>The acid resistance of the enamel in the individual was inferred from the phosphorus biopsied from the upper central incisors using spectrophotometric determination with molybdatesafranin.<BR>Results were as follows:<BR>1. After polishing with tooth paste prepared with a calcium carbonate base, an agar plate (AP), impregnated with 0.1 M lactate buffer solution of pH 4.0, of 2mm in thickness and 6.5mm in diameter was placed on the surface of the enamel for 3 minutes for pre-etching, and then a second agar plate was applied for 3 minutes. The phosphorus dissolved in the second agar plate was determined. The pattern of its distribution in 166 fourth-grade children of Group"A"corresponded to the normal distribution (Fig. 4), and those of 177 children in the fourth grade of Group"B"and 164 first-year students of junior high school of Group"B"showed a slightly normal distribution (Figs. 2 and 3). The average phosphorus determined were 1.2-1.3μg (Table 3).<BR>2. After polishing with tooth paste prepared with a calcium carbonate base, a non-woven, paper plate (NP) impregnated with 0.1 M lactate buffer solution of pH2.5 was placed on the surface of the enamel for 20 seconds for pre-etching, and then a second plate was applied for 3 minutes. Phosphorus dissolved in this plate was determined. The pattern of its distribution in 197 sixth grade children of Group"A"revealed a normal distribution significantly at the 95 per cent confidence limits (Fig. 6 and Table 3). The average phosphorus value and the standard deviation were 3.00μg and 0.73μg, respectively.<BR>3. It was observed that the application of a non-woven paper plate impregnated with 0.1 M lactate buffer solution of pH2.5 is an appropriate method for revealing the distribution of the acid resistance of the enamel if its distribution in the tooth population is normal curve. Moreover, this method can be applied without difficulty and the acid agent used was ascertained to be harmless.<BR>4. A slightly significant positive relationship was observed between the caries prevalance curve of the upper first molars of children whose upper central incisors had been classified as weak group and that classified strong and medium group with regard to the acid resistance determined by the above-mentioned method (Fig. 12).
- 有限責任中間法人 日本口腔衛生学会の論文