Effects of epigallocatechin-3-gallate modification on the bonding stability of an etch-and-rinse adhesive to intraradicular dentin

Abstract

Objective: To evaluate the effects of epigallocatechin-3-gallate (EGCG) modification on the bonding stability of an etch-and-rinse adhesive to intraradicular dentin, and to find a new strategy to improve the stability of bonding interface. Methods: EGCG was incorporated into Single Bond 2 (SB2) with the concentration of 200 mg/L and 400 mg/L respectively to fabricated experimental adhesives group A and group B, while Single Bond 2 without EGCG was used as control group. Laser scanning confocal microscope (LSCM) and scanning electron microscope (SEM) were used to observe the bacterial biofilm adherent to the surface of the cured adhesive. Micro-Raman spectrum was used to test the degree of conversion (DC) of adhesives. The push-out bond strength of instant testing and aging with thermocycling for 5 000 times were also tested. Results: Group A and group B showed inhibiting effect on the biofilm formation of Enterococcus faecalis and performed better with higher concentration. No significant differences were detected in DC among group A ([69.73±0.68]%), group B ([69.03±1.65]%) and control group ([70.06±1.62]%) (P>0.05), and the immediate push-out bond strength of control group ([10.45±2.00] MPa) was not compromised compared to group A ([10.02±2.03] MPa) and group B ([9.95±3.03] MPa) (P>0.05). After thermocycling for 5 000 times, group A ([7.01±1.39] MPa) and group B ([7.62±1.88] MPa) showed significantly higher push-out bond strength than control group did ([5.08±1.56] MPa) (P<0.05). Conclusions: EGCG modified etch-and-rinse adhesives showed anti-bacterial effect and enhanced bonding stability of intraradicular dentin-adhesive interfaces.