Dental caries and fluoride exposure in Western Australia.

Most water supplies in Western Australia (WA) have been fluoridated since about 1968, but one region has persistently resisted. Supplement use has been encouraged there, and fluoride toothpaste is widely used. Caries prevalence and caries experience in children in Perth (F- 0.8 mg/L) have declined steadily since fluoridation, but in the Bunbury region (F- less than 0.2 mg/L), caries measures remain higher than in Perth. The purpose of this study was to correlate the magnitude and timing of fluoride exposure with caries experience. Altogether, 592 randomly selected children born in 1978 (mean age, 11.8 years) in Perth and the Bunbury region provided residence and fluoride exposure information for the periods from birth to four and from four to 12 years of age. Caries experience was recorded clinically in accordance with DMFT and WHO criteria. Sixty-one percent had been continuous residents of fluoridated areas from birth to four years, and 51% between the ages of four and 12 years. Fluoride supplement use was low. By the age of 1.5 years, 42% had used toothpaste. The prevalence of caries was 0.38 in Perth and 0.61 in the Bunbury region, and mean DMFT scores were 0.89 (SD, 1.39) and 1.57 (SD, 1.60), respectively. Bivariate analysis revealed all fluoride exposure to be associated with reduced caries experience, but there were large correlations between some variables. When unconditional logistic regression analysis was used, the most important (p less than 0.05) odds ratios associated with no caries experience were for residence in a fluoridated area from four to 12 years of age and early use of toothpaste.(ABSTRACT TRUNCATED AT 250 WORDS)