Effect of matrix-metalloproteinase-inhibitors on bond-strength of a universal adhesive to dentin

Objectives: To evaluate the effect of different matrix metalloproteinase (MMP) inhibitors (2.0% chlorhexidine-CHX and 35% phosphoric acid-PA containing 1.0% benzalkonium chloride-BAC) on the shear bond strength (SBS) of a universal adhesive to dentin.
Methods: A total of 60 dentin surfaces were produced from sound mandibular incisors by wet grinding the buccal surfaces. Specimens were randomly assigned to six groups according to the surface treatments (n=10): Group I (control): 37% PA gel (N-Etch, Ivolar Vivadent), Group II: 35% PA gel containing 1.0% BAC (Select HV Etch, Bisco), Group III: 37% PA gel followed by 2.0% CHX (Klorhex, Drogsan Medical), Group IV: 35% PA gel containing 1.0% BAC followed by CHX, Group V: no treatment, Group VI: 2.0% CHX. Composite cylinders (Filtek Ultimate, Body A2, 3M ESPE) were bonded to the dentin surfaces using a jig after the application of a universal adhesive (Single Bond Universal, 3M ESPE). The specimens were stored in distilled water for 15 days, and SBS (MPa) were examined using a universal testing device at a crosshead speed of 1 mm/min. Failure mode distribution was also evaluated. One-way ANOVA test was used for data analysis (α=0.05).
Results: The highest mean SBS value was observed in Group IV (37,9 ±11,5) whereas the lowest value was observed in Group I (12,7 ±4,6). Group IV and VI showed significantly higher SBS than the other groups (p<0.05). Incorporation of BAC into PA did not improve the SBS of a universal adhesive to dentin as 2.0% CHX. The failure modes were mainly adhesive for all of the groups.
Conclusions: The bond strength of a universal adhesive to the dentin was affected by the application of the MMP inhibitors.