Different surface modifications combined with universal adhesives: the impact on the bonding properties of zirconia to composite resin cement

Objective The purpose of this study was to analyze the impact of plasma treatment and (universal adhesives) UAs on the bonding properties of zirconia. Material and methods Zirconia specimens ( N = 744; n = 186/pretreatment) were prepared, highly polished, and pretreated: (i) plasma (oxygen plasma, 10s, 5 mm), (ii) airborne-particle abrasion (alumina, 50 μm, 0.05 MPa, 5 s, 10 mm), (iii) airborne-particle abrasion + plasma, and (iv) without pretreatment (highly polished surface). Surface roughness ( R a ) and surface free energy (SFE) were measured ( n = 6/pretreatment). Tensile bond strength (TBS) specimens ( n = 180/pretreatment) were further divided ( n = 18/conditioning): Clearfil Ceramic Primer (PCG), All-Bond Universal (ABU), Adhese Universal (AU), Clearfil Universal Bond (CUB), G-Premio Bond (GPB), Futurabond U (FBU), iBond Universal (IBU), One Coat 7 Universal (OCU), Scotchbond Universal (SBU), and no conditioning. PCG was luted with Panavia F2.0 and the remaining groups with DuoCem. After storage in distilled water (24 h; 37 °C) and thermocycling (5000×; 5 °C/55 °C), TBS was measured and fracture types (FTs) were determined. Data were analyzed using univariate ANOVA with a partial eta square ( ƞ P 2 ), the Kruskal–Wallis H , the Mann–Whitney U , and the Chi 2 test ( P