岐阜県側木曽川流域における所謂斑状歯について
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概要
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High incidence of mottled teeth is present all over the regions centering around Shippo and Kamimori villages of Aichi prefecture. Geologically, the above regions are of diluvial formation of soils carried by the river Kiso and the river Shonai. The incidence of mottled teeth is considered by some workers to be probably due to the effect of the underground water coming from fluorine-containing are of the upper reaches of the river Kiso.<BR>If this interpretation be right, there should be more regions of mottled teeh in the basin of the river Kiso. At several regions of Gifu prefecture which are opposite to Shippo village acrosss the river, we carried out examinations of drinking water for fluorine, phosphoric acid, Ca, pH, etc., as well as investigations into the incidence of mottled teeth and dental caries, in order to gain knowlege on the factors responsible for the occurrence of mottled teeth. The main data obtained from the studies are given hereunder:<BR>1) Of the Gifu prefectural side of the basin of the river Kiso, the incidence of mottled teeth in the 1st to 6th graders of primary schools of Maemiya village of Inaba-county and that in the 4th to 6th graders of primary schools of Hashima city of Hashima county, was 3.9%, and 39, 6%, respectively.<BR>2) The enamel hypoplasia at the above places according to the classification of the Medical Affairs Bureau of Ministry of Welfare, shows the highest incidence in M<SUB>1</SUB>, followed by M±, M<SUB>2</SUB>, and M<SUB>3</SUB>, in that order, while B is quite negligible.<BR>3) The incidence of the so-called mottled teeth in Maemiya village shows no difference from area, while the incidence in Hashima city differs from area to area, ranging from 26.0 to 54.1%.<BR>4) Sex difference in the incidence of mottled teeth is not of statistical significance. The incidence according to primary-school grades declines in higher grades declines in higer graders at Maemiya village, but rises, on the contray, in Hashima city of Hashima city of Hashima county.<BR>5) Our investigations indicate that so-called mottled teeth do not produce such immunization against dental caries as do mottled teeth due to fluorine.<BR>6) Water examinations resulted in the detection of only a slight content of F; the Ca and PO<SUB>4</SUB> levels as the PH of the water within the usual range.<BR>The above studies point to that the enamel hypolasia in the regions in question is due to some other factor or factors than fluorine. Full clarification of the etiology requires further studies.