Background: dental fluorosis is a defect in the formation of the enamel by high fluoride concentrations during tooth development. It produces hypomineralization of the enamel by increasing the porosity, thus exposing the tooth to decay.
Objective: to determine the prevalence and severity of fluorosis in children aged 6 to 15 years.
Methods: a sample of 456 children was evaluated. The diagnosis of fluorosis was made through physical examination and the severity of the damage was described by using a modified version of Dean's scale.
Results: 270 children presented fluorosis (59.2 %). The most affected were children of 8 to 12 years, students of first to fifth year of primary school. The severity was mild and very mild in 90 % of cases. Tooth decay appeared in 55 % of children with fluorosis and in 43 % of children without fluorosis.
Conclusions: the prevalence of dental fluorosis is rapidly increasing. Tooth decay affected more often children with fluorosis. Assuming that the prevalence of fluorosis is due to excessive fluoride application rather than to environmental exposure is possible.