An investigation of children's dental fluorosis and intelligence in drinking water-type of endemic fluorosis area in Xi'an

Abstract

Objective To investigate the dental fluorosis and intelligence level of children in drinking water-type of endemic fluorosis areas in Xi'an, and to provide a scientific basis for development of prevention and control strategies. Methods In 2016, six drinking water-type of endemic fluorosis villages and one non-diseased village were selected as investigation sites in Xi'an. According to the detection rate and prevalence of dental fluorosis in children, six diseased villages were divided into three groups, the disease light-affected areas were Huidong and Xingnan, the moderate-affected areas were Liulin and Xiazhu, and the serious-affected areas were Hetou and Xiaoyang; and the Deng village was the non-diseased. A cross-sectional survey was conducted to collect 3 tap water samples in each village to test the fluorine content in water. For all children aged 8 to 12 years in diseased villages and 100 children aged 8 to 12 years in non-diseased villages, dental fluorosis examination and intelligence test were carried out. Results Mean value of water fluoride in non-diseased village and endemic fluorosis areas were (0.25 ± 0.01), (0.78 ± 0.43) mg/L, and the water fluoride content in two diseased villages was over 1.20 mg/L. The detection rate of dental fluorosis in children aged 8 to 12 (30.32%, 67/221) in diseased areas was significantly higher than that in non-diseased area (2.00%, 2/100; χ2= 31.32, P < 0.01). Children's IQ scores in the four groups were 108.68 ± 10.83, 102.54 ± 12.54, 101.70 ± 14.85, 93.45 ± 10.84, and the IQ scores were decreased with the severity of dental fluorosis, the difference in IQ scores was significant between the endemic fluorosis areas and non-endemic fluorosis area (P < 0.05); the percentage of children with IQ≤89 in endemic fluorosis areas was significantly higher than that innon-endemic fluorosis area (χ2= 22.02, P < 0.01). The IQ scores of children with dental fluorosis was 94.96 ± 13.75, and the IQ was 105.26 ± 10.19 in children with normal condition, the difference was significant (t= 5.61, P < 0.01), the mean value of IQ was decreased with the severity of dental fluorosis (F= 7.42, P < 0.05) , the percentage of children with IQ≤89 in patient was higher than that in normal children, the difference was significant (χ2= 45.70, P < 0.01). Conclusion Low level of water fluoride still has negative influence on children's dental health and intelligence, water improving and surveillance should be strengthened to ensure the health of children. Key words: Fluorosis, Dental; Child; Intelligence