Study of the relationship between well water and dental caries in Kurosecho

Abstract

We examined the relationship between fluorine ion density, pH, and chlorine ion density in drinking water and dental caries in the Nominoo area, Kurose-cho, Kamo-gun, Hiroshima, from the information about people who came to the School of Dentistry, Tokyo Medical and Dental University Hospital, with mottled teeth. I chose the Shimokurose elemetary school area, which is situated the west end of Kurose-cho, as a control area for the examination of the Nominoo area.It was found that the area of high fluorine ion density was an area of alluvial soil near Nominoo along the Kurose river, 1, 000m in north-south diameter, and 400m in east-west diameter. Fluorine ion density is comparatively low, 0.1-0.8ppm, in the water of a shallow well where the depth of underground water is less than 10m. In the water of a deep well more than 10m pleep high density, 1.00-8.60ppm, was detected.Between Nominoo elementary school area where fluorine ion density is high in drinking water and Shimokurose elementary school area where it is compatively low, it is hard to get an exact comparative value of prevalence ratio of pupils statistically because of few examples. But for the pupils of the higher grades, it was found obviously that their prevalence ratio has a tendency to increase in rather high fluorine ion density area. The same tendency is seen between people who use drinking water of high fluorine ion density and people who use drinking water of low fluorine ion density. And as for fluorine ion density and Ph, fluorine ion density is high on the alkalin side and decreases toward the acid side. That value is almost a straight line relation and a recurrent straight line is shown by the equation:y=2.58x-14.45The coefficient of correlation is:ρ=0.7718In this straight-line relation, chlorine ion density is highest at Ph 6.2-6.7, and fluorine ion density at 0.25 ppm-1.50 ppm.