Mineral Loss in Enamel and Dentine Relative to the ADJ

Methods: Fifteen human teeth were sectioned (3x3 mm x120 µm). Each section was mounted onto a glass slide and coated with acid-resistant nail varnish (control), leaving a small window (2x2 mm) of hard tissue exposed around the ADJ, exposing near equal portions of enamel and dentine. Sections were continuously exposed to orange juice for 6 hours, after which they were removed from the slides. Transverse microradiography was then used to measure surface mineral loss for both enamel and dentine, on five separate areas for both tissues, with the first area located adjacent to the ADJ.

Results: There were clear differences in average mineral loss between enamel and dentine. The mean (sd) mineral loss of each of the areas for enamel ranged from 3.3 (1.2) to 3.8 (1.3) µm, with no evidence to support a significant difference between the areas (p=0.532). The mean (sd) mineral loss of each of the areas for dentine ranged from 13.6 (1.7) to 19.1 (1.8) µm, with the lowest mineral loss at the area nearest the ADJ and the greatest mineral loss at the area furthest from the ADJ. There was evidence of differences between the areas in terms of dentine mineral loss (p<0.001), with statistically significant differences between each pair of areas (all bonferroni-corrected p-values £0.005).

Conclusions: Continuous exposure to an acidic drink resulted in greater mineral loss in dentine compared with enamel from the same specimen. There was no obvious difference in enamel mineral loss between each of the five areas, in contrast to dentine where mineral loss increased the further away from the ADJ it was measured.