Study On The Effects Of The Fusing Parameter On The Bonding Strength Of Titanium-porcelain

The popularity of metal alloys has dramatically increased over the last few years due to their mechanical properties. Recently, use of pure titanium and its alloys in prostheses has increased due to their attractive properties, such as biocompatibility, corrosion resistance, low density and high mechanical properties, titanium and its alloy are basic materials for applications in metal-ceramic coatings. Some authors suggest that the thermal expansions of the metal should slightly exceed that of the porcelain. It is of importance that porcelain should be strongly bonded to titanium substrate in order to achieve successfully long-term clinical use. To pursue the high titanium–ceramic bonding is still a concerned theme although commercial porcelain systems for bonding titanium are available today. Due to highly reactive nature of titanium at high temperatures, an excessive thick and nonadherent application, this constructed the weak region of the porcelain-titanium system. Some titanium-ceramic systems appear to be susceptible to oxidized film, loosed construction and low bonding strength between abutment and oxidized layer, which can cause weaker bonding strength of titanium- porcelain. The micro-arc oxidation (MAO) is a new technique which causes ceramic film growing on the surface of abutment. The oxidized film, having high bonding strength with abutment, is porous on surface and compact in internum. In addition, element can be changed in the film, so the oxidized film could be functional layer between titanium and porcelain, chemical bonding and mechanical bonding can be strengthened. Therefore, the aim of this study is to adjust the fusing parameter on titanium-porcelain system, and to employ the analytical model to determine the effective thermal contraction difference.Objective: To study the effects of microarc oxide treatment on the titanium-ceramic bonding strength. At the different parameter of fusing system, to study the effects of cooling rate on the compatibility between titanium and porcelain.Method: Titanium samples were prepared by the ISO9693, The specimens from each porcelain-metal combination were randomly assigned into different experimental cooling rate conditions, to employ the analytical model in order to study the effects of cooling rate on the compatibility between titanium and porcelain. A three-point-flexure-test was used to evaluate the bond strength of titanium porcelain bonded to cast pure titanium. SEM/EDS were taken to characterize the failed surface at the titanium-porcelain interface.Titanium samples were drawn randomly by microarc oxide treatment, the electrolytic solution was prepared with Na2SiO3 and deionized water, and same of the specimens were adapted preoxidation fusing system. Another specimen from each porcelain-metal combination was randomly assigned into different experimental cooling rate conditions. A three-point-flexure-test was used to evaluate the bond strength of titanium porcelain bonded to cast pure titanium. SEM/EDS were taken to characterize the failed surface at the titanium-porcelain interface.Results: After the cooling rate and MAO treatment, the results showed: with the increased the cooling rate, the bonding strength between titanium and porcelain were decline, As a result of the Tuebinger Gabel test showed, the 15℃?min groups was positive values of the effective thermal contraction difference, which reflected the expansion of titanium exceeding that of the porcelain, resulting in compressive residual stress states in porcelain. The de-bonded specimen with a large amount of porcelain retained on the metal surface .On the contrary, the 100℃?min group titanium-porcelain showed more discrepancy of the thermal expansion coefficients than other groups. As the SEM cross section showed the porcelain appeared dense and well bonded to the titanium substrate.After pre-oxidation treatment, the results showed: the bonding strength between titanium and porcelain was lower than no pre-oxidation groups. With the Pre-oxidation treatment the thickness of layer was thicker than on pre-oxidation. After MAO treatment, the results showed: different cooling rate have no effects on bonding strength between titanium-porcelain. The Tuebinger Gabel test also showed the same results between titanium-porcelain. As the SEM cross section showed the porcelain appeared dense and well bonded to the titanium substrate.