Study on the influencing factors of children's dental fluorosis prevalence

Objective Explore the impact factor of children's dental fluorosis, to provide a theoretical basis for prevention and control of dental fluorosis. Methods The 29 villages with water improvement projects for more than 5 years were selected as survey villages in Jiangsu, Shandong, Hebei, Anhui, Henan, Shaanxi Provinces by multi-stage random sampling. The investigation contents: ① basic information: including village annual income per capita, water fluoride, the term of water supply improvement; ② the water quality test: the levels of chloride, sulfate, total dissolved solids and so on in water were analyzed; ③the dental fluorosis: dental fluorosis of children aged 8-12 was examined with Dean method; ④ the dietary survey: the dietary nutritional status of 8-12 years old children was surveyed by duplicate portion study, and dietary fluorine was analyzed. Single factor regression analysis was adopted to analyze the relationship of average water quality index between every village, dietary nutrition and so on as independent variables respectively and 8-12 years old children's dental fluorosis prevalence rate and degree as dependent variable. Impact factors were selected by backward elimination method. Statistical significant indicators were further analyzed by multivariate regression analysis, and then multiple regression models were established. Results A total of 3 043 children aged 8 to 12 were investigated in 29 villages, and 270 children were in dietary survey. The average prevalence rate of dental fluorosis was 30.2% (919/3 043), in the range of 2.0% (2/100)-71.4% (30/42). The prevalence index of dental fluorosis was 0.55, ranging from 0.04 to 1.59. Dietary protein (X16) and VE (X17) were identified as the protective factors of dental fluorosis, and the standard partial regression coefficients (SPRC) were-1.537 4 and -0.695 1, respectively, according to multiple factors regression analysis. Water fluoride(X11) and chloride (X12), dietary fluoride (X13), copper (X14) and zinc (X15) were identified as risk factors of dental fluorosis (SPRC were 0.549 7, 0.432 7, 0.329 8, 1.400 9 and 1.023 3, respectively). The regression equation of the prevalence of dental fluorosis was: Ydental fluorosis = -54.854 3 + 19.770 6X11 + 0.121 3X12 + 4.280 2X13 + 30.773 5X14 + 9.264 9X15 -1.332 7X16 -2.384 1X17. The standard partial regression analysis showed riboflav (X26) can reduce the risk of dental fluorosis (SPRC = -0.930 2). Fluoride (X21) and chloride of water (X22), fluoride (X23), phosphorus (X24), zinc (X25) of dietary can aggravate the severity of dental fluorosis (SPRC were 0.357 0, 0.548 1, 0.262 6, 0.899 9 and 0.662 1, respectively). The regression equation of the prevalence of dental fluorosis popular index was: Ydental fluorosis popular index =-1.090 5 + 0.210 2X21 + 0.002 0X22 + 0.057 6X23 + 0.001 1X24 + 0.089 0X25 -1.473 3X26. Conclusion The increase of protein, VE and riboflav intaking can reduce or relieve the prevalence and severity of dental fluorosis. Key words: Dental fluorosis; Fluorosis index; Dietary nutrient; Water fluoride