Methods: The study was performed as an in situ- design with 16 participants. Eight bovine enamel specimens with an artificial gap were put into an intraoral appliance, worn by the participants according to the study protocol. Diagnostic impressions of the appliances were taken after 3d, 7d, 14d and 28d, before and after cleaning the enamel slabs with a toothbrush. At the same time and additionally at baseline quantitative laser fluorescence (QLF) measurements were performed in the area of smooth enamel surface and of the artificial gap. Results of QLF- analysis were correlated to the results of the diagnostic impressions.
Results: QLF- values decreased on the enamel surface (from 1695 to 1598) and in the area of the artificial gap (1789 to 1683) during the four weeks. The differences between baseline and the 3d, 7d, 14d and 28d measurements were significant (Wilcoxon test, p=0.001). ANCOVA with repeated measures showed a significant regression between the results of the diagnostic impressions after cleaning the enamel slabs and the QLF-values in the area of the artificial gap (p=0.0325, r =-130) and the QLF-values on the surface (p=0.0343, r =-113). No significant regression was found between QLF and impressions values before cleaning the specimens.
Conclusion: Participants with higher amounts of lactic acid in plaque showed a higher demineralization of enamel. This study was supported by 3M Espe, Germany.