[Effects of exogenous enzymes on the degradation of adhesive-dentin interfaces].

Objective: To compare the effects of exogenous enzymes on the degradation of adhesive-dentin interface.
Methods: Forty molars were sectioned to expose the middle-coronal dentin surface and randomly divided into two adhesive systems: an etch-and-rinse adhesive Adper Single Bond 2 and a self-etching adhesive G-Bond. After composite building up, the specimens were then randomly assigned to four groups(n=5 for each group)as follows: group 1, 24 h of water storage(the control group); group 2, six months of water storage; group 3, twelve weeks storage in artificial saliva containing clostridium histolyticum collagenase; group 4, twelve weeks storage in artificial saliva containing cholesterolesterase. The microtensile bond strengths(MTBS)were then tested. The failure modes and nanoleakage were analyzed.
Results: After aging treatments, the three aging groups showed significantly lower MTBS compared with the control group in both adhesive systems(P<0.05). For etch-and-rinse adhesive Adper Single Bond 2, the MTBS of group 3([19.6±3.5]MPa)was lower than that of group 2([23.4±4.2]MPa)and group 4([24.2±4.2]MPa)(P<0.05). For self-etching adhesive G-Bond, there was no difference on MTBS among different aging groups(P>0.05). SEM observation showed that, compared with the control group, water storage(group 2)and the exogenous enzymes(group 3 and 4)increased the nanoleakage expression(silver deposition)of both adhesive systems. Adhesive failure was the predominant fracture modes in all groups.
Conclusions: Storage in artificial saliva containing clostridium histolyticum collagenase or cholesterol esterase could be used to accelerate the degradation process of adhesive-dentine interface.