Effects of micro-arc oxidation on bond strength of titanium to porcelain

Due to the pronounced oxidative nature of titanium at high temperatures, an excessively thick oxide layer may form on its surface. This oxide layer could adversely affect titanium-porcelain bonding. The aim of the present study was to investigate the effects of micro-arc oxidation on the titanium-porcelain bond strength which was relevant to the titanium oxide layer．Twelve cast titanium specimens were prepared following the protocol ISO 9693. The test group was treated with micro-arc oxidation and the control group was treated with sandblasting. Contact angle and surface roughness were detected. SEM, XRD, and SEM/EDS analyses were performed on the titanium surfaces to ascertain bond failure. The groups were compared for their bond strength. The results showed that: there are differences in the surface morphology and the phase components of two groups. In addition, compared with the control group, the contact angle of the MAO group is smaller, but the surface roughness is similar. In the MAO specimen, the oxide layer was thin, and it was compact bonding with titanium and porcelain. The mean bond strength of the micro-arc oxidation group and the control group were 46.46 ± 4.35 MPa and 33.28 ± 2.24 MPa, respectively. While the improvement in bond strength was 39.6% for micro-arc oxidation group, it was statistically significant for the control group. These results suggest that the micro-arc oxidation technique is significantly effective in improving the bond strength of titanium-porcelain.