Dental Fluorosis and Fluoride Exposure in Western Australia

Abstract

Dental fluorosis in children is reported from many locations, and its prevalence may be increasing. This study aimed to measure fluorosis in 12-year-olds in fluoridated and non-fluoridated areas of Western Australia and to relate this to exposure. School dental clinics in Perth (F- 0.8 mg/L) and the Bunbury area (F- <0.2 mg/L) were the sampling units. Parents provided data on residence in fluoridated areas and on use of supplements and toothpaste. Exposure to water and supplemental fluoride between birth and four years was calculated. Clinical examinations (upper left central incisor) based on the TF classification of fluorosis (which requires teeth to be dried) were conducted for 338 children in Perth and 321 in the Bunbury region. Re-examinations (n = 50) gave a weighted kappa of 0.78. Contingency analysis estimated bivariate relationships, and multiple logistic regression estimated odds ratios (OR) for risk factors. Fluorosis prevalence in the Perth region was 0.40, and in the Bunbury region 0.33 (χ2 = 3.69, df = 1, p = 0.055). Prevalence was 0.44 in children with fluoride exposure equivalent to optimal water fluoridation and 0.20 among those with the lowest exposure (χ 2 = 35.99, df = 1, p = 0.0001). Increasing exposure was associated with higher fluorosis prevalence and higher TF scores, but overall, 27.3% of participants had TF score 1 (barely discernible), and only 9.4% had TF score ≥2. The odds of fluorosis were greatest for use of fluoride supplements in accordance with recommendations (OR = 4.63, 95% CI 1.97, 10.90) and extended residence in an area with fluoridated water (OR = 4.06, 95% CI 2.55, 6.44). All toothpaste-related variables had ORs > 1, but none was statistically significant, suggesting recall error. The findings suggest that supplement use by some children in 1978-82 provided too much fluoride, and that a small number of persons have undesirable fluorosis.