Effects of Protease Inhibitors on Dentin Erosion: an in Situ Study

Objective: This in situ study aimed to evaluate the effects of the inhibitors of matrix metalloproteinases (MMPs) and cysteine cathepsins on dentin erosion.

Materials And Methods: Ten volunteers participated in this study. Each volunteer wore an intraoral appliance containing 4 dentin specimens subjected to different treatments: deionized water as a control, 1 mM 1,10-phenanthroline (an MMP inhibitor), 50 µM E-64 (a cysteine cathepsin inhibitor), and 1 mM 1,10-phenanthroline + 50 µM E-64. The specimens were dipped in 5 ml of the respective solutions for 30 min at room temperature and then exposed to in vivo erosive challenges by rinsing with 150 ml of a cola drink (4 × 5 min/day) for 7 days. The substance loss of the specimens was measured by profilometry. The transverse sections of the specimens were examined using scanning electron microscopy. Thereafter, the demineralized organic matrix (DOM) of the specimens was removed using type I collagen enzyme and assessed by performing profilometry. The differences in substance loss and DOM thickness among the groups were analyzed by one-way repeated-measures analysis of variance (ANOVA) and Bonferroni's test at a level of P < 0.05.

Results: Protease inhibitors significantly reduced substance loss in comparison to that of the control group (all P < 0.05). A significantly thicker DOM was observed for the specimens treated with protease inhibitors than for the control specimens (all P < 0.05). No significant differences in substance loss or DOM thickness were found among the MMP inhibitor, cysteine cathepsin inhibitor, and MMP + cysteine cathepsin inhibitor groups.

Conclusions: The use of MMP and cysteine cathepsin inhibitors was shown to increase the acid resistance of human dentin, which may be due to the preservation of the DOM.

Clinical Relevance: The application of protease inhibitors could be considered an appropriate preventive strategy for dentin erosion.