The Effect of Various Composite Resin Types, Surface Treatments, and Repaired Materials on the Shear Bond Strength of Composite Resin Repair

Abstract

Background and Objectives: Composite resin are widely used in the field of restorative dentistry, as the time passes, composite resin restoration are subjected to failure. This in vitro study conducted to evaluate the effect of two types of composite resin, surface treatment, and three types of repaired materials on shear bond strength. Methods: Total of 120 undercut cylindrical cavities 8 mm in diameter in 2.5 mm in depth were cut at the center of self-cured acrylic resin blocks, the samples divided randomly according to the types of composite resin into 2 groups; microfilled and hybrid, the samples in each groups subdivided according to surface treatment; diamond bur and phosphoric acid. Then all the samples received bonding agent, these groups were subdivided into subgroups according to three composite repair materials. After that the samples were thermocycled manually 500 times, and then each bonded sample subjected to shear bond testing with a universal testing machine. Results: The results showed that groups filled with hybrid composite had higher mean shear bond strength than groups filled with microfilled. Groups received surface roughness with diamond bur had higher mean shear bond strength than groups roughened by phosphoric acid. Conclusion: The highest repair bond strength was obtained by roughening the hybrid composite surface with diamond bur. There was no any significant difference in shear bond strength among groups repaired with different repaired materials, while combination of surface roughness with diamond bur and repaired with microfilled composite had higher mean shear bond strength.