Effect of preoxidation of titanium on the titanium–ceramic bonding

To improve the titanium–ceramic bonding is a challenged theme because the bonding plays an important role in long-term performance of dental prosthetic implants. This study focused on the pre-heat treatment effect on the surface characteristics of titanium and the bond strength of the porcelain–titanium system. Phase, morphology, and oxide layer thickness of the pre-heat-treated titanium were evaluated. In particular, the bond strength of porcelain fused to pre-treated titanium was measured by using three-point bending test. Statistical analyses were made using one-way analysis of variance (ANOVA). The results revealed that with an increase in treatment temperature, the intensity of diffraction peaks of rutile-type titania formed on pre-treated titanium surface increased. With regard to the thickness of the oxide layer, a monotonous change with increasing treatment temperature was observed. The bond strength of the porcelain–titanium system was 27.6 MPa for untreated titanium, which is above the minimum value of 25 MPa specified in ISO 9693 standard for the three-point bending test. When titanium subjected to pre-heat-treatment at 600–850 °C, the values became the range of 23.7–34.5 MPa, indicating significant differences (p < 0.05). The highest value resided in the optimal pre-treatment temperature of 750 °C at which specimens also presented greater amounts of remained porcelains on the titanium side among all tested groups after bending test. On the basis of the data, the pre-heat treatment in air for titanium substrates might be a simple and effective method for strengthening the titanium–ceramic bonding.