RESUMEN
The shear bond strength of the composite resin to a CAD/CAM hybrid composite resin block (CRB) can be affected by the composition and microstructure of the hybrid CRB, surface treatment and the properties of the applied adhesive. In this study, the shear bond strengths between composite resin and the hybrid CRBs were measured to evaluate the effect of microstructure differences in hybrid CRBs on the bond strength. Ten conventional and reinforced hybrid CRBs developed by five domestic and international manufacturersand five universal adhesives currently used in dentistry were selected. After polishing the hybrid CRB surface, the specimens were divided into two groups. The first group was HF-treated to observe the microstructure by FE-SEM, and the second group was sandblasted with alumina, measured the surface roughness by CLSM, bonded with composite resin (diameter = 2.0mm) using universal adhesive, and stored in a 37 ℃ water bath for 24 hours, and measured the shear bond strength using a universal testing machine. The measured values were statistically analyzed using the Tukey-multiple comparison test (α= 0.05). It was observed that the size, type, and fraction of the filler particles contained in the regular and reinforced hybrid CRBs affected the microstructure, but the differences did not affect the shear bond strength. All five universal adhesives containing 10-MDP as the main functional monomer met the minimum bond strength (>20 MPa) required for clinical applications.