Bonding Effectiveness Of Zirconia After Different Sandblasting Procedures

Methods: Pre-sintered zirconia blocks (IPS e.max ZirCAD, Ivoclar Vivadent) were divided into one control (A) and four test groups (B-E) of three specimens each. Any surface treatment was performed in the control group (A). Groups B, C and D were sandblasted with 30µm SiO₂, 50µm Al₂O₃, and 110µm Al₂O₃, respectively, before sintering. Group E was sandblasted with 30µm SiO₂after sintering. For each treatment, the surface roughness was measured (Perthometer M4P, Mahr Perthen).  After sintering the zirconia blocks, a liner and a pressable ceramic (IPS e.max ZirPress, Ivoclar Vivadent) were fired. Sixteen micro-bars were obtained from each block and submitted to the micro-tensile bond strength (µTBS) test (LRX, Lloyd). Data were analyzed with one-way ANOVA .

Results: Sandblasting before sintering with 110µm Al₂O₃ (Ra=3.44±0.44µm), 50µm Al₂O₃ (Ra=2.32±0.46µm), and 30µm SiO₂(Ra=1.22±0.22µm) resulted in significantly higher roughness than sandblasting  after sintering with 30µm SiO2(Ra=0.46±0.11µm). The highest µTBS was measured when the sintered zirconia was sandblasted with 30μm SiO2 (26.79±14.80 MPa), which was significantly different from that of specimens that were sandblasted before sintering or were not treated.

Conclusions: Sandblasting zirconia before sintering enhances the surface roughness proportionally to the particle size of the sand used. Sandblasting with 30µm SiO₂ after sintering appeared to improve bonding between the veneering ceramic and zirconia.