CARIES FREQUENCY IN PERMANENT TEETH BEFORE AND AFTER DISCONTINUATION OF WATER FLUORIDATION IN KUOPIO, FINLAND

The piped water of Kuopio, Finland, was fluoridated in 1959. Owing to strong opposition by different civic groups, water fluoridation was st opped at the end of 1992. Objectives: The aim of this study was to exa mine the consequences of the discontinuation on dental health. Methods : In 1992 and 1995, independent random samples of all children aged 6, 9, 12 and 15 years were drawn from Kuopio and Jyvaskyla, a nearby low fluoride town whose distribution of demographic and socio-economic ch aracteristics was fairly similar to Kuopio's. The total number of subj ects examined was 550 in 1992 and 1198 in 1995. Caries was registered clinically and radiographically by the same two calibrated dentists in both towns. Results: In 1992, the mean DMFS values were lower in the fluoridated town for the two older age groups, the percentage differen ces for 12- and 15-year-olds being 37% and 29%, respectively. For the two younger age groups no meaningful differences could be found. In 19 95, the only difference with possible clinical significance was found in the 15-year-olds in favor of the fluoridated town (18%). In 1995, a decline in caries was seen in the two older age groups in the nonfluo ridated town. In spite of discontinued water fluoridation, no indicati on of an increasing trend of caries could be found in Kuopio. The mean numbers of fluoride varnish and sealant applications decreased sharpl y in both towns between 1992 and 1995. In spite of that caries decline d. Conclusions: These findings suggest that the decline of caries has little to do with professional preventive measures performed in dental clinics.