Endemic dental fluorosis associated with relatively low fluoride concentrations in the southern Free State, South Africa
Isolated high fluoride concentrations in the groundwater out of the rocks of the Tarkastad Formation were reported many years ago. The endemicity of dental fluorosis in the region underlain by these rocks, however, was not studied. This article reports on the first fluorosis study in this region. The pupils of 10 farm schools in the southern Free State constituted the sample. The teeth of 594 children of all ages were clinically and photographically examined. The drinking water was sampled at 245 sources on 203 farms. Ion specific analysis was used to determine the fluoride content of the water. Spatially generalized, it is a relatively low-fluoride area, but central statistics do not adequately describe the fluoride content of the water. Spatial variation characterizes the fluoride content of the groundwater. The fluorosis prevalence in the study area (>62%) was surprisingly high and the community fluorosis index was 1,5. The severity of fluorosis was predominantly low, but 4,6% of the children displayed loss of enamel. Spatial variation characterizes the occurrence of fluorosis in the area. The spatial variation pattern in the occurrence of fluorosis is only partially explained by that in the fluoride content of the drinking water. The optimum cariostatic concentration interval for South Africa might not be appropriate for this region.