Benchmark dose of saliva fluoride concentration in adolescents and it's relationship to the prevalence of dental fluorosis

Abstract

Objective To study the benchmark dose (BMD) of fluoride concentration in saliva, and to evaluate the significance of saliva fluoride on control and prevention of endemic fluorosis. Methods In September 2014, middle school students in endemic fluorosis areas and non-endemic fluorosis areas in North China Petoleum were selected as objects. The contents of fluoride in water, urine and saliva were determined. The correlation of fluoride content in water, urine fluoride and fluoride concentration in saliva was analyzed. According to the levels of the saliva fluoride concentration, the children were divided into 11 groups, < 1.00, 1.00-, 2.00-, 3.00-, 4.00-, 5.00-, 6.00-, 7.00-, 8.00-, 9.00-and ≥10.00 mg/L. The prevalence of dental fluorosis and defected dental fluorosis were investigated and the saliva fluoride concentration was calculated by Banch-Mark Dose Software. Results Compared with non endemic areas, the fluoride contents in water, urine and saliva [(2.13 ± 0.13) ,(1.29 ± 0.73), (4.01 ± 3.61) mg/L] were higher than that in endemic areas [(0.67 ± 0.13), (0.38 ± 0.08),(0.75 ± 0.12) mg/L, t = 158.730, 24.780, 18.114, all P < 0.01]. The fluoride concentration in saliva was positively correlated with the fluoride content in water and urine in endemic areas (r = 0.626, 0.945, all P < 0.01). The (BMDs and benchmark dose lower bound (BMDLs) were 0.91, 0.54, 3.72, 3.32 mg/L respectively, calculated by Banch-Mark Dose Software. With the increase of fluoride concentration in saliva, the prevalence of dental fluorosis and defect dental fluorosis had increased too, especially when the fluoride content in saliva was more than 4 mg/L. There were significant dose-response relationships between the urine fluoride and the prevalence of dental fluorosis and defected dental fluorosis. Conclusion The fluoride concentration in saliva could be used as one of the evaluation indexes of fluorosis, and the BMD of saliva fluoride concentration in endemic fluorosis areas is suggested as 0.91 mg/L. Key words: Dental fluorosis; Urinary fluoride; Saliva fluoride concentration; Dose-response relationship; Benchmark dose