Age as a determinant of severity of dental fluorosis in children residing in areas with 0.5 and 2.5 mg fluoride per liter in drinking water.

The purpose of this study was to investigate the influence of age on the severity of dental fluorosis in children exposed to drinking water with either low or high fluoride concentrations. The children selected for this study were aged 10-14 years, with 28 permanent teeth and at least 1 tooth pair with fluorosis. The children were permanent residents of districts in western Uganda with either 0.5 mg (n = 33) or 2.5 mg fluoride/l in drinking water (n = 186). All vestibular tooth surfaces were examined for fluorosis using the modified Thylstrup and Fejerskov (TF) index. In the high fluoride community, the proportion of teeth per child with TF scores > or = 4, and > or = 5 was significantly higher among children aged 13-14 years compared to those aged 10-12 years. Children's chronological age correlated positively and significantly with the median TF scores for all teeth, including early erupting (first molars and incisors) and late erupting teeth (canines, premolars and second molars). In linear regression analyses, the median TF score for all teeth, as well as for early erupting and late erupting teeth, increased significantly with age. On the other hand, in the low fluoride community there was no significant association between age and the severity of fluorosis. This study showed a significant increase in the severity of fluorosis with increasing age in a high fluoride community, whereas no change in severity with age was observed in a low fluoride community.