第１大臼歯におけるうしょく発病要因に関する研究

Abstract

The purpose of this study was to examine the factors in the dental caries incidence and the eruption of first molars. The subjects of this study were 177 school children who were born in 1976-1977 in Tomisato-cho (Chiba). The dental examination was carried out 20 times during the period from May, 1982 to July, 1985. Only first molars erupted in the survey period were used for the analysis. The following seven factors were selected (1) dmft (exclusion of deciduous incisors), (2) the age at the eruption time of the first molar (months), (3) the height of the children at the eruption time (cm), (4) length of the erupting periods of the first molar, until contact with the opponent tooth (months), (5) the plaque accumulation (OPI) on the occlusal surface before the beginning of the occulusion, (6) the plaque accumulation (OPI) on the occulusal surface after the beginning of the occulusion, and (7) the dental caries on the deciduous second molar (rate of decay). Discriminant and analysis was used in order to evaluate the relation between these factors and the incidence of dental caries on the first molar.The Lower first molar erupted earlier and took longer time until contact with the opponent tooth than the upper first molar. Moreover, the lower first molar had more dental plaque on the occlusal surface than the upper first molar before the beginning of the occulusion.The dental caries on deciduous teeth was related to the eruption time of the first molars. In particular, severe caries on the lower second deciduous molar seemed to hasten the eruption of the lower first molar earlier and to delay the beginning of occulusion as a result. Discriminant analysis indicated that the dental caries in deciduous teeth was related closely to the incidence of dental caries in first molars.From these results, we concluded that for caries prevention in first molars the prevention of caries in deciduous teeth, particularly in the second deciduous molars is important.