THE EFFECTS OF TEN YEARS OF DEFLUORIDATION ON URINARY FLUORIDE, DENTAL FLUOROSIS, DEFECT DENTAL FLUOROSIS, AND DENTAL CARIES, IN JIANGSU PROVINCE, PR CHINA

The aim of this study was to evaluate the effect on urinary fluoride, dental fluorosis, defect dental fluorosis, and dental caries of the defluoridation of drinking water for 10 years in Jiangsu province, PR China. In 2002, before defluoridation, 236 children in Wamiao and 290 in Xinhuai aged 8-14 years were recruited and in 2013, after 10 years of defluoridation, a further 68 children in Wamiao and 65 in Xinhuai, aged 8-10 years, were recruited. The effects of defluoridation were evaluated by examining the correlations between the prevalence of dental fluorosis and dental caries, and the urinary fluoride level. The prevalence of dental fluorosis and defect dental fluorosis in 2002 had a significant positive dose-response correlation with the drinking water fluoride with the coefficient correlations, regression equations, and p values being r=0.999, y=99.552/(1+ 40.049xe(-3.464x)), and p=0.017; and r=0.987, y=17.520x -6.950, and p=0.001, respectively. The prevalence of dental fluorosis and defect dental fluorosis were significantly decreased with the decreased drinking water fluoride in Wamiao in 2013 after defluoridation compared with the results in 2002. The prevalence of dental caries and the DMFT were slightly increased in Wamiao in 2013 compared with 2002 and slightly decreased in Xinhuai. However, the levels of DMFT in both villages in 2013 were at a low (Xinhuai) or very-low or low (Wamiao) level. In 2002, the prevalence of dental caries and the DMFT had a U-shaped dose-response correlation with the drinking water fluoride concentration. This study suggests that defluoridation of drinking water is effective for controlling endemic fluorosis in China and that the role of fluoridation of public water supplies for the of control dental caries needs to be further studied.