BACKGROUND: Salt fluoridation is considered a cost-effective community strategy for reducing caries.

AIM: To evaluate the effect of school-based and domestic distribution of F-salt to schoolchildren residing in a disadvantaged community.

DESIGN: Seven hundred and thirty-three schoolchildren (12-14 years), attending two public schools, were enrolled; one was assigned to intervention (IS), whereas the other served as reference (RS). Subjects in IS were given access to F-salt (250 ppm F) in marked jars at school lunch and through free supply for domestic use. The 2-year caries increment and progression rate, assessed from bitewing radiographs, was scored. Information on diet, oral hygiene, and fluoride exposure was collected through a baseline questionnaire.

RESULTS: The dropout rate was high (IS 27%; RS 18%). At baseline, the IS children displayed more unfavourable risk factors and a higher caries experience than RS children. There were no significant differences in total caries increment or proximal progression rate between the two schools. A negative correlation (r = -0.29; P < 0.05) between the amount of delivered salt and the caries progression rate was, however, noted. No side effects were reported.

CONCLUSIONS: F-salt was not effective in this setting. Still, the findings indicate that salt may be a beneficial source of fluoride in schoolchildren provided that compliance can be secured.