Evaluating the Effects of Sandblasting on Micro-Shear Bond Strength and Flexural Strength of Zirconia

Abstract

Background and Objective: Various techniques have been introduced to improve bond strength of zirconia which may negatively affect flexural strength. This study aimed to evaluate the effects different sandblasting parameters on micro-shear bond strength (MSBS, Mpa) and biaxial flexural strength (BFS, Mpa). Methods: In this in vitro study zirconia blocks were cut into 180 discs for MSBS and BFS tests (90 specimens in each group). For each test they were divided into control group and 8 experimental groups according to the type of sandblasting regimen (pressures of 4 or 6 bar, duration of 14 or 21 seconds, and alumina powder sizes of 50 or 110 μm, n=10). A universal testing machine was used to determine MSBS and BFS. X-ray diffraction (XRD) analysis was then performed. Findings: Groups with 110μm particles (4 bar- 14 s, 6 bar- 14 s, 4 bar- 21 s and 6 bar- 21 s with MSBS values of 34.43±5.99, 35.21±6.39, 27.17±3.95 and 28.66±3.92 Mpa respectively) had significantly higher MSBS values compared to the control group (p<0.001, p<0.001, p=0.034, p=0.005; respectively). Groups with 110 µm- 21 s sandblasting regimen (with pressure of 4 and 6 bar with BFS values of 1031.69±90.00, 1062.56±91.29, 962.30±93.24 respectively) and those with 50 µm- 6 bar- 21 s sandblasting regimen had statistically significant lower BFS values compared to the control group (p<0.001). According to XRD analysis, groups with 110 μm powder size and 21 s sandblasting resulted in more monoclinic phase. Conclusion: This study demonstrated that sandblasting with larger powder size and lesser duration could increase MSBS without any negative effects on BFS.