Caries progression in 12- to 16-year-old schoolchildren in fluoridated and fluoride-deficient areas in Brazil.

Abstract

Water fluoridation may reduce the rate of caries initiation, but relatively little is known of its effect on rates of caries progression through the enamel and the dentin. This longitudinal study was designed to compare rates of caries progression in fluoridated and fluoride-deficient areas. Approximal caries progression was evaluated on two standardized sets of bitewing radiographs taken at a 12-month interval of 290 12- to 16-year-old Brazilian schoolchildren. Pitts' scoring system was used to measure caries progression on conventional bitewing images. Caries progression data on the occlusal, free-smooth, and approximal surfaces of the anterior teeth were collected via clinical visual examinations. The mean rate of approximal caries progression in school-children living in fluoridated areas (0.54) was found to be 62% lower than that in children from fluoride-deficient areas (1.41). When progression rates were adjusted for the initial number of decayed surfaces per subject, differences were statistically significant for lesions located at the inner half of the enamel at baseline (11% in the fluoridated areas vs. 16.5% in the fluoride-deficient areas). Multivariate logistic regression analysis revealed that residence in a fluoride-deficient area remained a significant risk factor for caries progression after controlling for caries prevalence (D1FS), number of cavitated carious lesions, whether tooth type was molar or premolar, and toothbrushing frequency. These results suggest that water fluoridation reduces the rates of caries progression through the enamel and dentin, but the effect was more pronounced for lesions in the inner enamel than for those in the dentin.