MMP9 and dental fluorosis: After correcting the mixed factors such as urinary fluoride, maternal education level, and per capita annual income of the family, the multivariate Logistic regression analysis showed that BALP, OC, MMP-2, MMP-9, PTH were independently related to the risk of dental fluorosis, suggesting that BALP, OC, MMP-2, MMP-9, PTH were closely related to the occurrence of dental fluorosis.