To study the effects of water fluoride and tea fluoride on the occurrence of dental fluorosis in children, and to provide a basis for scientific prevention and control of the disease.

From April to September 2020, Baolongshan Town with qualified water fluoride but no habit of drinking brick tea, Xingyao Town with qualified water fluoride and habit of drinking brick tea, Baokang Town with exceeded water fluoride but no habit of drinking brick tea, and Wuliyasitai Town with exceeded water fluoride and habit of drinking brick tea were selected as survey sites in Inner Mongolia Autonomous Region based on historical monitoring data. In all Gacha (villages) of 4 towns, a survey was carried out on residents' drinking water, brick tea drinking habits and children's dental fluorosis detection, and the water fluoride, tea fluoride exceeding standard rates, daily per capita intake of brick tea fluoride and the detection rate of children's dental fluorosis were calculated. At the same time, multivariate logistic regression was used to analyze the influencing factors affecting the occurrence of dental fluorosis in children.

In 2020, a total of 165 water samples were collected in 4 towns of Inner Mongolia Autonomous Region, and the total water fluoride exceeding standard rate was 38.18% (63/165). A total of 320 tea samples were collected, the tea fluoride exceeding standard rates in Xingyao Town and Wuliyasitai Town were 96.38% (213/221) and 89.90% (89/99), respectively; the daily per capita intake of brick tea fluoride was 5.67 and 7.35 mg, respectively. A total of 1 652 children were examined for dental fluorosis, and 639 cases were detected, the detection rate was 38.68%. The detection rates of dental fluorosis in boys and girls were 37.18% (322/866) and 40.33% (317/786), respectively, with no significant difference between sexes (χ² = 1.72, P = 0.104); the detection rates of dental fluorosis in children aged 8 - 12 years were 43.93% (105/239), 40.50% (147/363), 46.57% (163/350), 30.56% (88/288) and 33.01% (136/412), respectively, with statistical significant difference among ages (χ² = 26.07, P < 0.001); the detection rates of dental fluorosis in children in Baolongshan, Baokang, Xingyao and Wuliyasitai towns were 0.68% (2/293), 14.09% (31/220), 24.79% (89/359) and 66.28% (517/780), respectively, with statistical significant differences among regions (χ² = 213.05, P < 0.001). Multivariate logistic regression analysis showed that when the fluoride content in water was 1.2 - < 2.0, 2.0 - < 2.5, and ≥2.5 mg/L, the risk of dental fluorosis in children was 3.93, 6.60, and 9.02 times of water fluoride content < 1.2 mg/L; when the daily per capita intakes of brick tea fluoride was 3.6 - 7.0 and > 7.0 mg, the risk of dental fluorosis in children was 2.94 and 3.90 times of daily per capita intakes of brick tea fluoride ≤3.5 mg; the risk of dental fluorosis in children aged 10 years was 1.81 times of children aged 8 years; the risk of dental fluorosis in children in Xingyao, Baokang, and Wuliyasitai towns was 22.35, 40.93, and 151.58 times of Baolongshan Town, respectively.

The prevalence of dental fluorosis in children still exists in Inner Mongolia Autonomous Region, and the detection rate of dental fluorosis is high. High water fluoride and high tea fluoride are the main risk factors for dental fluorosis in children.

Drinking water; Tea; Dental fluorosis; Influence factors