EDC Inactivates MMPs in Adhesion to Radicular Dentin

Etching of dentin and bond application activates matrix metalloproteinases (MMPs), contributing in the deterioration of the dentin collagen network of the hybrid layer. Recent studies demonstrated that collagen cross-linking agents strengthen the collagen network and inhibit MMPs. The aim of this in vitro study was to evaluate the effect of a cross-linking agent (carbodiimide, EDC) used as additional therapeutic primer in luting fiber posts to radicular dentin and in preventing hybrid layer degradation. The null hypothesis tested was that EDC improves fiber post bond strength and preserves it during aging.

Method:

Extracted intact single-root teeth were selected. Samples were endodontically treated and a 10 mm post space was prepared in each sample. 80 specimens were selected and equally and randomly divided into four groups (n=20) according to the adhesive protocol: 1) All Bond 3 (Bisco); 2) All Bond 3 + 0.3M EDC; 3) XP-Bond (Dentsply); 4) XP-Bond + 0.3M EDC. EDC was applied after phosphoric acid etching for 1 min. Fiber posts (RelyX Fiber Post) were luted with a dual-cure resin cement (Core-X Flow) and cured. Teeth were cut in 1 mm-thick slices and pushed until failure with an Instron Machine immediately (t=0; n=10 per group) and after 12 months of storage in artificial saliva (t=12; n=10 per group). Results were statistically analyzed with one-way ANOVA test. Statistical significance was set at p=0.05. 

Result:

EDC significantly affected fiber post bond strength at t=12 (p=0.0001) but not at t=0 (p=0.632). No influence was revealed by different adhesive systems in affecting bond strength to radicular dentin. 

Conclusion:

Application of EDC after etching procedures in radicular dentine reduces MMPs activity over time, because it avoided bond strength values reduction after artificial aging. Thus, the null hypothesis was partially accepted. Further in vivo investigations are necessary to confirm these results.