The relationship between dental fluorosis and tooth fluoride concentration - a study in an endemic area

Abstract

Objective: To determine the relationship between dental fluorosis (DF) severity and fluoride [F] concentration in tooth and water in DF endemic areas. Methods: Life-long residents from two DF endemic communities were studied. Forty-five extracted teeth were collected and analyzed for DF severity and tooth [F]. Thylstrup-Ferjeskov Index (TFI) was used to measure DF severity and instrumental neutron activation analysis (INAA) for tooth [F] concentration. Water from regional wells was also collected (n=9) and analyzed for F content using specific ion F electrode. Results: Water [F] varied between 0.2ppm and 4.7ppm. TFI scores ranged from 0 to 6; [F] from 120ppm to 2,140ppm in enamel and 304ppm to 4,800ppm in dentin. No correlation was found between DF severity and [F] in enamel (rs=0.22,p=0.15) and dentin (rs=-0.19,p=0.20), nor between water [F] and [F] in enamel (rs=-0.09,p=0.65) and dentin (rs=-0.11,p=0.56). Weak correlation between DF severity and water [F] (rs=0.38,p=0.04) was found. Linear regression analysis showed that TFI couldn’t be predicted from a linear combination of the independent variables (age, enamel and dentin [F]). When enamel, dentin and water [F] were used as independent variables in the linear regression (predict DF severity), only water [F] showed influence in DF severity (p=0.013;t=2.67). Conclusion: Even in areas of endemic DF, tooth [F] didn’t correlate with DF severity and the relationship between water [F] and DF severity was very weak. Therefore, tooth [F] may not be a good predictor/indicator of DF severity.