DEAN, H. TRENDLEY : National Institute of Health, Division of Infectious Diseases, Investigation of Dental Caries, Washington, D. C. (June 2, 1939).

(1)          Major conclusions of limited epidemiological studies of caries (con­current with such studies of chronic endemic dental fluorosis) : (a) Among children of verified continuity of exposure, a larger percentage is caries-free in communities where domestic water-supplies contain higher amounts of fluorides (F) than in those in which waters of lower fluoride concentrations are used. This limited immunity to caries is apparently operative in deciduous as well as permanent teeth; and, in the latter, independently of mottled enamel. (b) Analysis of caries rates, on the permanent teeth of 14,651 white children (age 12-14 years) in South Dakota, Colorado, and Wisconsin, indicates that, in the same state, the amount of caries is less in mottled-enamel areas than in normal areas. (c) Since the mineral composition of the domestic water appears to have an important bearing on the incidence and amount of caries, the possibility of partially controlling caries through the communal water- supply warrants thorough epidemiologico-chemical study.

(2)          Additional studies of the relation of domestic water to caries, includ­ing certain epidemiological aspects of oral L. acidophilus, applied to 885 white children (12-14 years), variables such as age, sex, color, and diet being equalized by s rrpling methodology—sunlight intensity, by location of cities studied—yielded the following findings : (a) Two Illinois cities (Galesburg and Monmouth), using domestic water closely similar in source and mineral compositior, show almost the same low caries-rates—201 and 205 carious permanent teeth per 100 children, respectively. Two nearby cities (Macomb and Quincy) using domestic water unlike, in type and mineral composition, that in Galesburg and Monmouth, had caries rates respectively double and treble those at Galesburg and Monmouth. Galesburg and Monmouth water supplies contain respectively 1.8 and 1.7 p.p.m. of fluorine ; the Macomb and Quincy waters, only 0.2 p.p.m. (b) Using approximal surfaces of the four permanent superior incisors as basis of measurement, there was sixteen times as much interproximal caries in Macomb and Quincy as in Galesburg and Mon­mouth. Epidemiological aspects of oral L. acidophilus, in saliva, closely re­flected differences in caries rates between Galesburg and Quincy. Quantity of amylase in saliva disclosed no group-population differences between Galesburg and Quincy. From an epidemiological standpoint, it is difficult to ascribe these differences to any cause other than the common water-supply.

References: Public Health Reports, 53 (Aug. 19), 1938; 54 (May 26), 1939 (with P. Jay, F. A. Arnold, Jr., F. J. McClure, and E. Elvove).

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