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

Abstract: 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 10min in orange juice (OJ) followed by 10min in deionised water; Group 2, continuous 10min in OJ followed by 10min 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 −0.3μm, 95% CI: −6.1 to 5.5). The mean difference between Groups 3 and 4 was 8.9μm (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. [Copyright &y& Elsevier]