Abstract: Objective To evaluate the effect of sandblasting conditions including sandblasting time, sandblasting pressure and sandblasting alumina powder size on shear bond strength between zirconia core and veneer indirect composite resin. Methods 250 zirconia bars were randomly divided into 25 groups according to different sandblasting conditions. The control group did not receive sandblasting. Shear bond strengths between zirconia and indirect composite resin were measured and compared for each group using universal testing machine. Also, fracture mode of each group was observed. Results The shear bond strength was significantly increased as the size of alumina powder and sandblasting time increased (P < 0.0001; P < 0.0001). The shear bond strength was significantly increased from 0.1 MPa to 0.2 MPa (P = 0.036) and did not significantly change with a sandblasting pressure from 0.2 MPa to 0.4 MPa (P = 0.609) or from 0.4 MPa to 0.6 MPa (P = 0.689). The possibilities of the fracture mode type C were higher as the bonding strength increased. Conclusion A sandblasting condition of 21s, 0.2 MPa, and 110μm is recommended for dental application to improve the bonding between zirconia and indirect composite resin.

Key words: zirconia, sandblasting, shear bond strength, failure mode