Influence of sandblasting parameters and luting materials on microshear bond strength to a CAD/CAM hybrid ceramic material

Objective: To assess the influence of sandblasting parameters (applied pressure and grain
particle size) on the microshear bond strength (μSBS) of Vita Enamic (VE) CAD/CAM hybrid
ceramic to two different resin cements.
Materials and Methods: One-hundred VE specimens were fabricated and allocated to 5 pretreatment groups (n=20/group): no treatment, 50 μm Al2O3 (2 bar), 50 μm Al2O3 (3.5 bar), 110 μm Al2O3 (2 bar) and 110 μm Al2O3 (3.5 bar). After pretreatment, surface roughness (Ra) was determined using a profilometer. The topography of pretreated surfaces was examined with Scanning Electron Microscopy (SEM). Each group was further divided into two subgroups according to type of luting material; subgroup (a): G-CEM LinkAce and subgroup (b): Single bond universal and RelyX Ultimate. After bonding, μSBS was measured with a Universal Testing Machine. Data were statistically analyzed using ANOVA and Tukey HSD tests (α=.05).
Results: Specimens air-abraded with 110 μm Al2O3 and pressure 2 bar showed the highest but insignificant μSBS compared to other sandblasted groups (P < 0.05). μSBS values (MPa) improved in the following order: 110 μm (2 bar) > 50 μm (2 bar) > 110 μm (3.5 bar) > 50 μm (3.5 bar) > control. Regardless the Al2O3 size, μSBS improved when sandblasting pressure was 2 bar while decreased with 3.5 bar groups. RelyX Ultimate showed higher μSBS than G-CEM LinkAce.
Conclusions: Sandblasting of VE surface by (2 bar) pressure and the use of conventional resin cement in association with universal adhesive system were required to achieve satisfactory bond strength values.