A comparison of in vitro erosion-like mineral loss between continuous and intermittent acidic exposure with and without human saliva.

AIM

This in vitro study aimed to compare erosion-like mineral loss following intermittent or continuous acidic exposures, and considered the role that human saliva may play.

MATERIALS AND METHODS

180 bovine enamel blocks were divided randomly into four equally-sized groups and exposed to one of the 4 protocols 6 times daily over 6 days (total acidic exposure time of 6h): Group 1, continuous 10 min in orange juice (OJ) followed by 10 min in deionised water; Group 2, continuous 10 min in OJ followed by 10 min in stimulated saliva; Group 3, ten 1-min OJ exposures alternating with ten 1-min deionised water exposures; Group 4, ten 1-min OJ exposures alternating with ten 1-min stimulated saliva exposures. Specimens were stored in a remineralising solution between acidic exposures. Sections were cut and transverse microradiography was used to measure lesion depth in each specimen.

RESULTS

Mean (sd) lesion depths were 21.5 (8.1), 21.2 (6.2), 81.7 (12.2) and 72.8 (12.4) μm for Groups 1-4, respectively. Significant differences existed between all protocols except Groups 1 and 2 (mean difference -0.3 μm, 95% CI: -6.1 to 5.5). The mean difference between Groups 3 and 4 was 8.9 μm (95% CI: 3.2-14.7).

CONCLUSIONS

Repeated, intermittent exposure to an acidic drink in vitro resulted in greater lesion depth than a continuous exposure of the same duration. Saliva offered some protection against intermittent acidic exposure.