Objective To investigate the relevance of age and dental fluorosis with serum calcium (Ca) and phosphorus (P) in children at 8-14 years of age in a coal-burning fluorosis (CBF) area of Guizhou Province, and discuss the levels of serum Ca and P affected by fluorosis in children across different age groups.
Methods A cross-sectional study was conducted to investigate the prevalence of dental fluorosis in 486 children (n=366 for CBF area, n=120 for control area) between 8 and 14 years of age. Then 190 children were selected by age stratified sampling to determine the concentrations of serum Ca and P. According to the Tanner stage criteria, the cases were merged into three age groups (preadolescence, 8 to 10 years; early adolescence, 11-12years; middle adolescence, 13-14 years) to analyze the difference of serum Ca and P in children of the CBF area and the control area across selected age groups. Variations of serum Ca and P were also analyzed among the children with different stages of dental fluorosis.
Results The dental fluorosis prevalence rates and the urine fluoride concentrations of children in the CBF area were both higher than those of the control group (χ2dental fluorosis=265.130, P=0.000; Zurinary fluorosis=-7.716, P=0.000). Increased serum Ca level (Zpreadolescence=-4.022, P=0.000; Zearly adolescence=-3.289, P=0.001; Zmiddle adolescence=-3.952, P=0.000) and declined serum P level (Zpreadolescence=-2.080, P=0.037; Zearly adolescence=-3.889, P=0.000) were found across all age groups compared with corresponding control groups, and only the serum P level in the middle adolescence group was not statistically different. Among the three age groups, there showed no statistical differences in both serum P and Ca levels of children in the CBF area (HP=0.560, P=0.756; HCa=0.296, P=0.863). There were no differences among the children with different stages of dental fluorosis, except the serum P levels between children with very mild and mild dental fluorosis (H=-24.207, P=0.015). Dental fluorosis degrees showed a positive correlation with age only (r=0.336, P<0.01).
Conclusion Fluoride poisoning could lead to non-progressive changes in serum Ca and P in young or minor fluorosis children.
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