Abstract
We collected 338 references no the epidemiology of dental fluorosis in Japan, from which we chose 248 articles pertaining to the field work of the disease. We found that reports of dental flurosis had been made in all the perfectures of Japan (46 prefectures) except Miyagi. Of these 46 prefectures, 36 areas in 22 prefectures were examined continuously for a long period. Of the 36 areas in 22 prefectures, 15 areas in 12 prefectures were examined several times by the same researchers. The areas in which the prevalence of dental fluorosis decreased or disappeared were 4 in number; that is, in Aso (Kumamoto Pref.), Funaki (Yamaguchi Pref.), Kasaoka (Okayama Pref.), and Ikeno (Aichi Pref.),
In Japan it was about 1950 that the fluorine concentration of drinking water began to be generally measured.
Before 1949, there were 52 reports made concerning dental fluorisis, but fluoride concentration was measured in only 7 of them, and the others gave no evidence to show that the disease was caused by fluoride. However it was late confirmed that 31 of these reports had correctly examined dental fluorosis.
In and since 1950, 20 reports were made in which there was no description of fluoride concentration, and 11 reports stating that dental fluorosis occurred at 0.3 ppm fluoride concentration and below.
Regarding these 11 reports, we could not confirm that the desease was caused by fluorosis, either because no follow-up survey was made or because it was difficult for us to confirm the validity of the results.
In the literature we gathered the highest concentration of natural content of water fluoride was 23 ppm at Oga (Shiga Pref.), according to the report by Minoguchi and others ('56). In Japan, dental fluorosis, first reported by Fukui ('25), has been examined for 60 years. But 55 % of the literature was pubished during the 10 years from 1950 to 1960.
This fact shows that dental fluorosis studies were of very wide prevalence during that period. This prevalence was noticed not only in the field of dentistry but in medicine and other fields.
