Dental fluorosis in rural school-children in the Shaanxi province, China

Objectives: Assess the prevalence and severity of dental flourosis in 12-13 years old children, living in communities with different fluoride concentration in drinking water and, thereby, gain information on the relationship between water-quality and fluorotic changes in teeth, - in a Chinese setting. Methods: Four hundred and seventy-seven children from 13 different schools were divided into 5 groups, according to the waters' fluoride concentrations: A: °Ü 0.6 mg/l, B: 0.8-1.4 mg/l, C: 1.6-2.6 mg/l, D: 3.1-38 mg/l, E: 4.5-7.6 mg/l. Clinical examinations were made under field conditions, and dental fluorosis was assessed on buccal surfaces of maxillary right central incisors, using the Thylstrup/ Fejerskov index (TFI). The univariate GLM ANOVA test was used for comparison of group means. Results: The prevalence of dental fluorosis varied from 36.8% to 97.4% according to the fluoride concentration of the drinking waters. The differences of mean TF-scores between all groups were statistically significant (p<0.001) except between groups D and E. Mean TF-scores increased with the fluoride content of the drinking water, from TF-score 0.6 in group A to TF-score 5.2 in group E. Conclusion: Dental fluorosis is endemic in some rural parts of the Shaanxi province. In low-fluoride areas (0.3-0.6 mg F/l) the severity of fluorosis was low, and may be without social and clinical importance. However, even in villages with drinking-water well within the recommendations of WHO (< 1.5 mg F/l), severe fluorosis could be observed. Based on these considerations, we would recommend that the fluoride content of drinking water in Shaanxi should be < 0.6 mg/l.