Three hundred seventy-four 12- to 14-year-old children were examined to determine modified tooth surface index of fluorosis (TSIF) scores, and to assess the association among fluoride enamel opacities and water fluoride levels, preschool dietary patterns, and dentifrice consumption. The subjects included boys and girls of both black and white races who reported life-long residence in either Augusta or adjoining Richmond County. "City" children had communal water consistently fluoridated at levels of 0.9 to 1.2 ppm. "County" children had water variably fluoridated at levels of 0.2 to 0.9 ppm. TSIF scores were recorded on each included tooth and the highest TSIF tooth score was noted for each subject. The frequency of TSIF scores in all subjects was analyzed for dental arch symmetry and for association with city/county residence. The frequency of TSIF scores then was analyzed separately for "city" children and "county" children for an association with race, gender, preschool dietary habits, and dentifrice ingestion. Chi-square analysis revealed that higher TSIF scores were associated with city children significantly more than with county children. There was no association of TSIF scores either in the city children or the county children with respect to gender, race, preschool dietary patterns, or dentifrice ingestion. TSIF scores were bilaterally symmetrical, but were higher in the maxillary arch than in the mandibular arch.