Abstract: Objective　To analyze the relationship between thyroid hormone abnormality and type 1 selenodeiodinase gene (DIO1) gene polymorphism in children with dental fluorosis. Methods　From June 2018 to June 2019, 169 children aged 7-12 years were randomly selected from the historical water fluoride area and non-water fluoride area of Tianjin to test the level of dental fluorosis. Urine samples were collected and the level of urinary iodine was determined by As3+-Ce4+ catalytic spectrophotometry. Blood samples were collected, TSH, FT3 and FT4 were detected by chemiluminescence, and the gene polymorphism of DIO1 rs2294512 was detected by sequenom SNP. The role of DIO1 gene polymorphism in dental fluorosis and thyroid hormone abnormality was studied by multivariate Logistic regression analysis after genotyping of DIO1. Results　The level of FT3 was higher in children with dental fluorosis (P＜0.05), and the level of FT4 was lower (P＜0.05). The abnormal rate of FT3 was as high as 40.0% in dental fluorosis group, and which was higher than that of normal children (P＜0.05). The abnormal rate of FT4 was reduced to 3.33%, and which was lower than that of normal children (P＜0.05). Among the children with DIO1 AA genotype, the incidence of dental fluorosis was more likely to lead to higher FT3 (OR=6.357, 95%CI: 1.808-22.347, P=0.004).　Conclusion　The FT3 level of dental fluorosis children with AA genotype of DIO1 gene rs2294512 is more likely to be higher.

Key words: fluorosis, dental, polymorphism, single nucleotide, thyrotropin, free triiodothyronine, free thyroxine, DIO1