The Influence of Latitude and Distance From Seacoast On Dental Disease

Abstract

Studies of dental disease in the United States, South Africa, Australia, and New Zealand are analyzed graphically and statistically. A suggestive pattern emerges for the United States showing dental disease (chiefly caries) to increase with latitude and with distance from seacoast. In observations from the Southern Hemisphere a similar pattern, inverted, is found in South Africa. Variation with latitude is apparent in Australia. A group of climatological factors, sunshine, rainfall, temp., and relative humidity, together with the chemical composition of water supplies, probably account for most of the variations in dental disease. The major factors involved in variation with latitude appear to be sunshine and temp. Temp. varies almost entirely with latitude and may be linked to dental caries through its effect on the caloric requirements and water intake. The consumption of carbohydrates seems to be greater in northern latitudes. Data from 41 cities in the United States show caries to be slightly, but not significantly, higher in these cities than in adjoining rural areas. Major factors involved in variations with distance from seacoast appear to be fluorides, total water hardness, and relative humidity.