RESUMO
OBJECTIVES: To test the hypothesis that fluoride varnish is effective in reducing demineralization (white spot) lesions adjacent to bonded orthodontic brackets. DESIGN: Two similar samples of extracted bovine incisors, with bonded orthodontic brackets, were separated into an experimental group (fluoride varnish was applied) and control group (no fluoride varnish) to examine the preventive effects of fluoride varnish. SETTING AND SAMPLE POPULATION: The dental clinic of the State University of Maringá--UEM (Maringá, Paraná, Brazil). Thirty-eight extracted bovine incisors with bonded orthodontic brackets. EXPERIMENTAL VARIABLE: Fluoride varnish was applied topically to half of the sample of extracted bovine teeth. No varnish was applied to the other half. OUTCOME MEASURE: The depths of enamel demineralization (white spot) lesions were measured from polarized light microscopy images using image analysis software. RESULTS: The teeth in both the experimental and control groups had been exposed to a cariogenic environment twice a day for 35 days. Those teeth that had been treated with two applications of fluoride varnish (one at the outset and another 15 days later) demonstrated about 38% less mean lesion depth than teeth where no varnish had been applied. CONCLUSION: Orthodontists may wish to consider the application of fluoride varnish during fixed orthodontic therapy to help reduce the development of enamel white spot lesions.