RESUMO
Objective To understand the defluoridation effect in the historical severe endemic fluorosis areas of Shandong Province,and to analyze characteristics of children's dental fluorosis and related factors.Methods In 2015,using cross-sectional survey,11 villages in historical severe endemic fluorosis counties were selected for water fluoride test according to previous investigation of endemic diseases in Shandong Province.In which,4 normal water fluoride villages,4 excessive water fluoride villages and 3 villages without water improvement were included.Dental fluorosis in children aged 7 to 12 was examined and urine fluoride was measured.Logistic regression was used to analyze the related factors affecting the detection rate of dental fluorosis.Results A total of 732 children aged 7 to 12 were examined,with total detection rate of dental fluorosis 73.2％ (536/732).The detection rate of dental fluorosis was 31.0％ (65/210),86.7％ (176/203) and 92.5％ (295/319) in the villages with normal,excessive and without water improvement villages,respectively.And the differences were statistically significant (x2 =270.498,P ＜ 0.01).The prevalence of dental fluorosis in girls (77.4％,264/341) was significantly higher than that in boys (69.6％,272/391,x2 =5.337,P ＜ 0.05),and the dental fluorosis prevalence in elderly group (10-12 years old,76.9％,382/497) was higher than that of younger group (7-9 years old,65.5％,154/235),the difference was statistically significant (x2 =10.445,P ＜ 0.05).In water fluoride normal villages,the detection rate of dental fluorosis in girls (40.0％,36/90) was higher than that in boys (24.2％,29/120,x2 =6.033,P ＜ 0.05).In water fluoride unqualified villages,the dental fluorosis prevalence rates in boys and girls were 89.7％ (243/271) and 90.8％ (228/251),and the difference was not statistically significant (x2 =0.202,P ＞ 0.05).The urinary fluoride content of children with dental fluorosis was higher than that of non-fluorosis children [(4.5 ± 2.7) vs (1.9 ± 1.5) mg/L,t =-8.125,P ＜ 0.01].Logistic analysis showed that the risk of children's dental fluorosis in unqualified water fluoride village was 14.362 times high than that of normal water fluoride villages.The risk of dental fluorosis in children with high urinary fluoride was 2.497 times higher than that in normal urinary fluoride group.The risk of detecting moderate and severe fluorosis in children in the elderly group was 2.270 times higher than that in the younger group.The risk of detecting moderate and severe dental fluorosis in girls was 1.988 times higher than that in boys.The risk of detecting moderate and severe dental fluorosis in children in unqualified water fluoride villages was 49.190 times higher than that in normal water fluoride villages.Conclusions Water-quality-improvement project is an effective means to control the epidemic of dental fluorosis in children in severe fluorosis areas.Age,gender and water fluoride are influencing factors associated with dental fluorosis.
RESUMO
Objective To investigate the influence of different water-improving defluoridation projects and different water-improving years on children's dental fluorosis,and to provide a scientific basis for further defluoridation of drinking water.Methods Totally 1/4 endemic fluorosis villages in all agricultural-related areas of Tianjin were selected by random sampling method from 2016 to 2017.The situation of water-improving defluoridation project was investigated in these villages.The ways of water improvement included municipal water supply,double pipe network,barreled water,low fluorine well and centralized water supply.The years of water improvement were ＞ 15,＞ 10-15,5-10,and ＜ 5 years,respectively.Totally 821 water samples (surface water,barreled water and groundwater) were collected.Fluoride ion selective electrode method was used for determination of water fluorine content.According to the "Diagnosis of Dental Fluorosis" (WS/T 208-2011),the prevalence of dental fluorosis in children aged 8 to 12 was examined.Results A total of 524 villages with drinking water endemic fluorosis and 35 870 children aged 8 to 12 were investigated in Tianjin.The water improvement rate was 73.28％ (384/524).Water fluoride qualified village accounted for 53.24％ (279/524).The detection rate of dental fluorosis was 47.98％ (17 209/35 870),the detection rate of dental fluorosis was different with different water improvement methods (x2 =1 955.742,P ＜ 0.05).Children's dental fluorosis detection rate in the area of municipal water supply was lower (33.19％,4 121/12 416),while that in double pipe network reconstruction area was 43.37％ (995/2 294).Children's dental fluorosis detection rates in the areas of barreled water supply,low fluoride well and centralized water supply were higher (58.47％,6 268/10 720;66.84％,1 719/2 572;53.75％,623/1 159).The median of water fluoride in the renovated area of municipal water supply was 0.24 mg/L,and the proportion of villages with water fluoride ≤ 1.2 mg/L was 100.00％ (133/133).With the increase in water-improving years (more than 10 years),children's dental fluorosis prevalence [＞ 15,＞ 10 ～ 15 years were 17.41％ (428/2 459),14.19％ (266/1 875)] in the areas of municipal water supply reached the control standards (≤30％).Conclusions The improvement of the municipal water supply network is thorough,which can meet the requirement of continuously ensuring the safety of drinking water for residents,especially those over 10 years.Other forms of water-improving need to be further optimized.