The prevalence of development defects of enamel and dental caries in New Zealand children receiving differing fluoride supplementation, in 1982 and 1985.

Seven hundred and twenty-seven 9-year-old children resident in Hawke's Bay were examined in 1985, 3 years after a baseline survey of a cohort of the same age group. Children were allocated to one of four fluoride-history groups on the basis of the responses of parents to a questionnaire, which also gave information on infant feeding and household water source. Examination conditions were duplicated, and children were examined by the same examiner using a modification of the DDE Index. The prevalence of diffuse defects in the low fluoride (LF) group (24.3 percent) was lower (P less than 0.001) than in the fluoridated water (WF) group (50.8 percent), the PT group who had used tablets to 5 to 6 years of age (53.1 percent), and the CT group who had used tablets continuously (54.7 percent). There were 2.9 percent of children with contralateral pairs of teeth with diffuse opacities in the LF group compared with 22.9 percent in the WF group, 18.7 percent in the PT group, and 36.0 percent in the CT group. For European children, 9.7 percent had post-eruptive defect sub-types. Defect prevalence could not be related to infant feeding or water source in unfluoridated areas. There had been a significant increase in the prevalence of diffuse defects in the WF, PT, and CT groups, but not the LF group since the baseline survey. There was also an increase in the numbers of children considered to have an unsatisfactory appearance due to either continuous or diffuse opacities--from none in 1982, to 24 (3.7 percent) in 1985. In the 3 years since the baseline survey there had been considerable reductions in the caries prevalence in all groups (P less than 0.001).