Dentine Fluoride as a Biomarker of Fluoride Intake and Fluorosis

The main hypothesis of this study is that the dentine fluoride of exfoliated primary second molars is a good indicator of the cumulative intake of fluoride and may be related to future permanent tooth fluorosis.

Objective:    To correlate dentine fluoride levels obtained from exfoliated teeth with cumulative fluoride intake data and age-related fluorosis data obtained from the Iowa Fluoride Study (IFS).

 Methods:    Exfoliated primary second molars collected from IFS subjects were used to determine dentine fluoride values in 90 samples via micro-diffusion and ion-specific electrode techniques.  Spearman rank correlations were used to evaluate the relationships between dentine F and fluoride intake measures reported for specified ages and age intervals.  Other analyses investigated the relationship of dentine fluoride to fluorosis.   

Results:    The 90 subjects were 55.6% female, and predominantly White (95.6%).  Dentine F determinations, measured in micrograms F/g, ranged from 0.85 to 701.75 micrograms F/g (mean  193.50 micrograms F/g, sd 149.64 micrograms F/g).   Significant (p < 0.05) positive correlations  were identified between dentine F measurements and the longitudinally-based AUC (Area Under the Curve) measures of reported F intake in mg, whether or not adjustment was made for body weight, although the rank correlations were modest ( 0.26 - 0.39).  In contrast, results assessing potential relationships between dentine F and reported fluoride intake at specific ages tended to be weaker, except for age 5 results which were similar in magnitude to AUC results.   A modest correlation (r=0.33, p=0.0041) was found between dentine F levels and a quantitative measure of fluorosis measures based upon the number of affected zones (FRI score of 2 or 3) in the permanent incisors/first molars. 

 Conclusion:   Dentine F levels are modestly associated with F intake and with permanent incisor and 1^st molar fluorosis scoring.