Bacterial adhesion, which is an important aspect in order to maintain zirconia restorations without marginal infiltrations or periodontal alterations, proved to be satisfactorily slight; Scarano et al. reported a degree of coverage by bacteria of 12.1% on zirconia as compared to 19.3% on titanium.64 Rimondini et al. confirmed these results with an in vivo study, in which Y-TZP accumulated fewer bacteria than Ti in terms of the total number of bacteria and presence of potential putative pathogens such as rods.65 Surfacial roughness in this context appears very important; Kou et al. compared different polishing systems for zirconia and concluded that polishing creates surfaces similar to the just sintered ones and smoother than only grinding surfaces.66 These studies indicate that zirconium oxide can be suitable for implant abutment but more clinical and mechanical trials are necessary for a complete understanding of behavior of zirconia abutment throughout a long time period. Edelhoff has proposed inlays and onlays with a zirconium oxide core. In order to realize these restorations, an occlusal reduction of almost 2 mm is necessary, and the axial reduction must be of 1.5 mm with a cavosurfacial angle of 100–1208.