| Conventional Ni-Cr substrates for the porcelain fused to metal restoration have potential toxicity to body. Precious metal is excellent, but the high price limits its wide use. Titanium-porcelain restorations earn more clinicians'concern because of its excellent biocompatibility and low price of titanium. The porcelain-veneered titanium restoration has not been used in clinic commonly, because the bond strength betweem titanium and porcelain is still lower than that of conventional Ni-Cr/porcelain restoration and the price of import porcelain for titanium is too expensive to be accepted. This study was projected on the development of GGL titanium body porcelain based on GGW titanium bond porcelain and G-1 titanium opaque porcelain developed by previous work of our research team. The other content of this study was to investigate the mechanism of bond between titanium and porcelain in order to improve the bond strength between them. The results of the study are as follow:Silicate glass was chosen as matrix. The content of SiO2, Na2O, K2O, Al2O3 and B2O3 was adjusted in order to get low fusing point, low coefficient of thermal expansion and good mechanical character, which was for matching with the GGW Ti bond porcelain and G-1 Ti opaque porcelain developed by previous work of our research team. The result showed the coefficient of thermal expansion of GGL titanium body porcelain is 8.1×10-6/℃, which was matching with that of GGW titanium bond porcelain and G-1 titanium opaque porcelain, 8.29×10-6/℃and 8.9×10-6/℃. That means the residual stress between any two porcelain layers is low enough to prevent the failure of restorations. And the three point flexure bond strength of titanium and porcelain developed by our research team is 36.42±1.05 MPa, which is similar with Super porcelain TI-22.The effects of sintering condition on mechanical property of GGL titanium body porcelain were studied. The results showed that a good integration property could be obtained at vacuity/760℃/3min. In such sintering condition the mechanical character of GGL titanium body porcelain was similar with or higher than Super porcelain TI-22 and Ti-Bond, with bending strength of 85.24±1.82 MPa, Vickers hardness of 412.80±13.83 kgf/mm2 and fracture toughness of 1.03±0.04 MPa/m1/2.The influence of artificial saliva on the adhesion between titanium and porcelain at different pH and fluoride concentration was measured. Samples were immersed in three artificial saliva: pH2.7,pH7.0/ F-100 ppm and pH2.7/ F-100 ppm for 1h, 1d, 7d and 30d. The results have shown a remarkable decreasing of bond strength between titanium and porcelain in group pH2.7/ F-100 ppm for 7d and 30d, compared with control group. But the bond strength had no change at 1d. Researchers reported F- in oral environment after using fluoride products would disappear at 1d. Therefore oral fluoride products have no effect on bond strength between titanium and porcelain.The content of Sn in GGW titanium bond porcelain was adjusted in order to investigate the mechanism of bond between titanium and porcelain and to improve the bond strength between them further. The result of three point flexure bond strength, SEM and EDS showed the change of Sn in titanium bond porcelain could induce the change of bond strength between titanium and porcelain and the element distribution at the interface. When the wt% of SnO2 was 15%, the bond strength was the highest, which was 39.46±3.60 MPa, and the collection of Sn was found in interface in such case. That may mean Sn attend the reaction between Ti and porcelain.To investigate the effect of Sn on the bond between titanium and porcelain, Sol-Gel technology was used to introduce Sn2+ into the interface between titanium and porcelain. The result of X-ray diffraction analyses, differential scanning calorimetry and infrared spectrum showed that the SnO film formed by Sol-Gel technology was produced at 300℃, composed by SnO and SnO2, and became steady after 500℃, composed by SnO2 only. The result of three point flexure bond strength was highest when the heat-treatment temperature was 300℃, which means SnO prevent the over oxidation of surface of titanium. In the same time Sn was found in the interface again, which may be another proof that Sn attends the reaction at the interface between titanium and porcelain.
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