PTH and dental fluorosis: Spearman correlation analysis showed that the urinary fluoride level and the extent of dental fluorosis were positively correlated with BALP, MMP-2, and MMP-9, and negatively correlated with OC and PTH, suggesting that there was a clear dose-effect relationship between BALP, MMP-2, MMP-9, OC, PTH, and urine fluoride levels.