The Effect of Two Adhesive Agents on Shear Bond strength Between Fresh Dental Amalgam and Resin Composite

Abstract

Objective: To assess and compare the results on the bond strength of two adhesive agents that bond fresh amalgam to two types of composite restorations, and to check the mode of bond failure.
 Methods: Sixty standardized circular cavities were prepared in a block of polymethyl methacrylate with standardized dimensions. Fresh amalgam was condensed to fill the cavity, then a gelatin mold with standardized dimensions was placed over the fresh amalgam,and the composite resin was bonded to the amalgam. Samples were assigned into three main groups, each containing (20) samples. G1: Amalgam bonded to composite without adhesive agent, G2: Amalgam bonded to composite by single bond universal adhesive, G3: Amalgam bonded to composite by scotch bond MPP, and each group was divided into two subgroups of (n=10) (Nanofill and Nanohybrid composite) to measure shear bond strength, which was followed by evaluation of debonding in all samples under a stereomicroscope to assess the mode of failure.
 Results: All The results showed that G3 has higher shear bond strength than G1 and G2, and this is statistically significant at (p=0.001, p=0.005) respectively, while G1 has the lowest shear bond strength and a statistically non-significant difference from G2 at (p=0.539). It was also found that the type of composite resin has no effect on bond strength and statistically non-significant difference was found for any of the sub-groups. Following debonding of all the samples, they were examined under a stereomicroscope, and the adhesive failure present was about (%65), and mixed failure present about (%35), while cohesive failure was (%0).
 Conclusions: Highest bond strength was found with Scotch bond multi-purpose plus (SBMPP) agent compared to other groups. The strength of the fresh amalgam bonding to the composite resin without an adhesive agent was low. The bond strength with single bond universal adhesive was lower than with the SBMPP system.