DIGITAL RADIOGRAPHIC MEASUREMENT OF APPROXIMAL CARIES PROGRESSION IN FLUORIDATED AND NONFLUORIDATED AREAS OF RIO-DE-JANEIRO, BRAZIL

The effect of fluoridation on approximal caries progression was invest igated using serial digitized bitewing images and conventional film im ages of 290 12-16-year-old schoolchildren who were lifetime residents of either Rio de Janeiro (a fluoridated area) or Mangaratiba and Angra dos Reis (non-fluoridated areas) in the state of Rio de Janeiro, Braz il. One examiner scored a maximum of 28 approximal surfaces of posteri or teeth per subject using both methods. The intraexaminer reliability for rating lesion depth with digital images was comparable with that of the conventional bitewing films (namely, intraclass correlation of 0.99 and weighted Kappa scores of 0.82, respectively). Approximal surf ace D1S was 3.17+/-0.25 (s(x)) in fluoridated areas and 6.64+/-0.44 in non-fluoridated areas. After 1 year, the rate of caries progression i n approximal surfaces was significantly lower in the fluoridated areas (0.54+/-0.14) as compared with the non-fluoridated areas (1.41+/-0.20 ) using Pitts' scoring system for conventional bitewing radiographs (P <0.001). Similarly, the digital radiographic method was able to detect subtle differences in approximal caries progression in the enamel and the dentin (overall mean: 0.34 mm/year in fluoridated areas vs 0.49 m m/year in nonfluoridated areas, P<0.05). The two radiographic methods were strongly correlated (r(s)=0.7). Assuming a constant rate over tim e, these results indicate that lesion progression from the outer half of the enamel into the outer half of the dentin takes approximately 3- 4 years in schoolchildren from the fluoridated areas compared to 2 1/2 years in the non-fluoridated areas.