Cooperation of phosphate monomer and silica modification on zirconia ceramic

Objectives: This study aimed to investigate the efficiency of silica-coating by tribochemical modification on Yttrium-oxide-partially-stabilized zirconia (YPSZ) ceramics. The application of phosphate monomer (MDP) and a silane coupling agent on silica-coated YPSZ was also investigated. Methods: 10x10 mm zirconia and titanium samples were used in this study. Samples were grit-blasted by silica-coated alumina or alumina air-abrasion. An x-ray photoelectron spectroscopy was used to analyze the surfaces of the samples. The average roughness of the samples with silica-coated and alumina air-abrasion were evaluated. Silica-coated YPSZ samples with a mixture of silane coupling agent and MDP monomer were prepared for shear bond strength test. Silica-coated YPSZ samples with the silane coupling agents and alumina air abraded YPSZ samples with MDP monomer were also investigated. A resin-based adhesive Rely^TM X ARC, 3M ESPE) was applied to the YPSZ samples. 8.0x2.0 mm titanium disc was placed on the adhesives and pressed perpendicular with a vertical load (1 kg/10 min). Samples were submitted to thermal cycling for 10000 cycles (5-55°C, 1 min). The results (n=8) were statistically analyzed by ANOVA followed by t-test (p<0.01). Results: The average surface roughness of tribochemically modified YPSZ samples was significantly lower (p<0.01) than that of titanium. The relative concentrations of silicon on tribochemically modified titanium surfaces increased 17.8±0.6%, whereas that of YPSZ increased 8.8±0.3%. Silica-coated samples with the silane coupling agents and alumina air abraded samples with MDP monomer showed higher shear bond strength (p<0.01) than that of the other samples even after thermal cycling. Conclusions: The silica-coating on YPSZ ceramics by tribochemical modification was not efficient compared with titanium given the higher mechanical toughness of the densely sintered ceramics. Stable shear bond strength was achieved on silica-coated YPSZ ceramics with the cooperative interaction of phosphate monomer and silane coupling.