Bonding to Zirconium-Alumina Ceramic: Microtensile versus Shear Test

Objective: This study evaluated the effect of 3 surface conditioning methods on the microtensile (MTBS) and shear bond strength (SBS) between the resin cement and a glass infiltrated zirconium/alumina ceramic. Methods: Twenty-seven blocks (5x5x4mm) for MTBS and 27 ceramic discs (diameter:6 mm, thickness:2 mm) for SBS (n=9/per group) were fabricated and ultrasonically cleaned for 5 min in deionized water. Three surface conditioning (SC) methods were evaluated: (1) Airborne particle abrasion (110 µm Al2O3), (2) Laboratory silica coating (110 µm SiOx) (Rocatec Pre and Plus, 3M ESPE), (3) Chairside silica coating (30 µm SiOx) (CoJet, 3M ESPE) and then silanized (ESPE-Sil). Experimental groups were as follows: Gr1:MTBS-SC-1; Gr2:MTBS-SC-2; Gr3:MTBS-SC-3; Gr4:SBS+SC-1; Gr5:SBS+SC-2; Gr6:SBS+SC-3. The resin cement (Panavia F, Kuraray) was attached to the conditioned ceramics in polyethylene molds and for microtensile test the resin cement was applied under the load of 750g for 10min. The cemented blocks were sectioned in two axes (x and y) with a diamond disk under coolant irrigation in order to obtain non-trimmed specimens (sp-sticks) with 1mm² of bonding area (14 sticks/block). Both tests were carried out in a universal testing machine (1mm/min). Results: In both MTBS (P<0.01) and SBS (P<0.001), SC-2 (26.9±4.1 and 27.1±7.7 MPa) and SC-3 (26.1 ±2.3 and 23.9±2.2 MPa) exhibited s significantly higher results than those of SC-1 (21.6±3.8 and 17.1±1.7 MPa), respectively (ANOVA and Tukey's test, α=0.05). The test method appeared to have no significant influence on the results of bond strength (P=.196). Conclusion: Both chairside and laboratory silica coating methods followed by silanization performed similar regardless of the mechanical tests and improved the resin bond to glass infiltrated zirconium/alumina ceramic when compared to alumina abrasion and silanization.