Comparison of Shear Bond Strength of Composite to Amalgam with the Use of Different Bonding Agents

Amalgam is a safe and effective restorative material in direct restorations. One of the conservative methods for the repair of a fractured amalgam restoration is the use of adhesive materials like composite resin. Therefore the aim of this study was to evaluate the bond strength of composite resin to amalgam with the use of different bonding agents.
In this in vitro study, 52 acrylic cylinders were made and amalgam containing 43% Ag was condensed into these cylinders. After keeping the amalgam samples at room temperature for 24 hours, the amalgam surfaces were abraded with a diamond bur and all the samples were immersed in an ultrasonic bath. Then the specimens were divided into 4 groups of 13 samples, and each group was treated with different boding agents as follows: group (1), amalgam alloy primer total etch (Single Bond); group (2), amalgam alloy primer self-etch (G Bond); group (3), amalgam G Bond; and group (4), amalgam Single Bond. Composite resin was bonded to prepared amalgam specimens with the use of translucent polyethylene mold and cured by LED Turbo, followed by testing with an Instron machine for shear bond strength. Finally data were analyzed with one-way ANOVA and LSD tests.
In this study, the highest bond strength value was recorded in specimens bonded with G Bond bonding agent (9.06 MPa) and the lowest value was recorded in specimens bonded with Single Bond bonding agent (5.14 MPa). The mean shear bond strength values in 4 groups exhibited statistically significant differences (p value = 0.001).
G Bond bonding agent yielded higher bond strength between amalgam and composite resin than other bonding agents used in this research.