Influence of Dentin Etching on MMP Mediated Collagen Degradation

Dentin matrix metalloproteinases contribute to collagen degradation in resin-dentin interfaces. Objective: To determine if collagen degradation is influenced by dentin etching procedures. Methods: Human dentin beams were 1) untreated, 2) 10wt% phosphoric acid-demineralized (PA), 3) 0.5M EDTA-demineralized, 4) treated with Clearfil SE Bond primer (SEB) or 5) treated with Xeno V (XE). Beams were stored in artificial saliva. In half of the groups, 2wt% chlorhexidine digluconate (CHX) was added. C-terminal telopeptide (ICTP) determinations by radioimmunoassay were performed on the supernatants after 24h, 1 and 3 wk. ANOVA and Student-Newman-Keuls multiple comparison were performed. Between storage times, Friedman's and Wilcoxon pair-wise tests were used (p<0.05). Results: Means (SDs) of ICTP concentrations (µg/l) are shown. Significant differences within a subgroup are indicated by numbers in rows, lower case letters among subgroups within one time period and upper case letters among the three time periods.  Conclusion: EDTA, PA, SEB or XE produces enough demineralization to permit MMP cleavage of collagen. Hydrophilic monomer infiltration protects demineralized collagen from degradation and may exert a prolonged inhibitory effect of chlorhexidine on MMP. Acknowledgements: CICYT/FEDER MAT2008-02347/MAT, JA-P08-CTS-3944, P07-CTS-2568, R21-DE019213-01, R01-DE015306-06 from NIDCR.