Effects of etching and micro-arc oxidation on bonding strength of titanium to porcelain

Objective: to investigate the effects of etching and micro-arc oxidation(MAO) technique on the bonding of porcelain to titanium. Methods: 50 non-cast titanium strips(25mm×5mm×0.5mm) were randomly divided into five groups(Group A to E, 10 strips per group), and treated according to the requirement of ISO 9693. All the specimens were sandblasted with 110# Al2O3particles after polished with SiC paper. Group A was the non-treated group as control. Group B and Group D were immersed by 35%HNO3-5%HF for 1min and Group D was subjected to the surface treatment with the micro-arc oxidation technique. Group C and Group E were subjected to the surface treatment with the micro-arc oxidation technique and Group E then etched by 35%HNO3-5%HF for 1min. The porcelain was burned onto the treated surface of titanium and the thickness of porcelain was 1 mm. Three-point bending test was carried out for the measurement of bonding strength, and the surface morphology and roughness of the specimens were evaluated with scanning electronic microscopy.Statistical analysis was conducted with SPSS 17.0 statistical software(α= 0.05). Results: A rough and porous coating wasformed on the surface of titanium after the MAO treatment. Compared with Group A, the bonding strengths of porcelain to titanium in Groups B to E increased after the MAO treatment(P 0.05). Bonding strength of all Ti-porcelain groups were higher than the minimum requirement of ISO 9693. There is no statistical difference between the micro-arc oxidation and the combination of acid treatment and micro-arc oxidation. Conclusions: The etching and micro-arc oxidation technique increases the bonding between porcelain and titanium. Acid treatment is also conductive to the bonding while the micro-arc oxidation is more conductive.