Anti-proteolytic property and bonding durability of mussel adhesive protein-modified dentin adhesive interface

Abstract

Objectives: To evaluate the effect of mussel adhesive protein (MAP) on collagenase activity, dentin collagen degradation and microtensile dentin bond strength (μTBS). Methods: Three groups were designed: 1. experimental group: treated with MAP; 2. positive control: treated with GM6001 (collagenase-inhibitor); 3. negative control: treated with distilled water (DW). For collagenase activity, Clostridiopeptidase-A was added to each group (n=5), and collagenase activity was assessed by colorimetric assay. For dentin collagen degradation, thirty dentin slabs were allocated to the three above groups (n=10). Dentin collagen degradation was evaluated by measuring released hydroxyproline by colorimetric assay after being incubated in Clostridiopeptidase-A for 7 days. For microtensile bond strength, sixty human third molars with flat dentin surfaces were etched by phosphoric acid and then assigned to the three above groups (n=20). An etch-and-rinse adhesive system was applied to all three groups as stated in standard clinic protocol. The test of μTBS was performed before and after thermocycling and collagenase challenge. Results: The collagenase activities (nmol/min/mg) in the group of MAP was significantly less inactive compared to the group of GM6001 and DW (MAP<GM6000<DW, p<0.01). The hydroxyproline concentrations (μg/mL) was significantly less in the group of MAP compared to the group of GM6001 and DW (MAP<GM6000<DW, p<0.01). While there was no significant difference in the immediate μTBS (MPa) among three groups (p>0.06), the value of μTBSs after thermocycling and collagenase challenge was significantly greater in the group of MAP and GM6001 compared to the group of DW (MAP, GM6000>DW, p<0.001). Significance: MAP inhibits collagenase activity, prevents dentin collagen degradation, and delays the deterioration of the dentin bonding of composite restoration over time.