Development Of GGW Titanium Bonding Porcelain And The Effect Of Titanium Treatment On Titanium-ceramic Bonding Strength

The technique of titanium-porcelain for dental restoration has made a great progress due to the biological demanding of dental material in recent years, but the porcelain-veneered titanium restoration has not been used in clinic commonly. It is because that the bonding strength of titanium/porcelain is still lower than that of conventional Ni-Cr/porcelain and the price of porcelain-veneered titanium restoration is too expensive to be accepted. The purpose of this study was to improve the bond strength of titanium/porcelain by two ways: development of a new titanium bonding porcelain and treatment of titanium surface before porcelain fused on it.Titanium bonding porcelain has a strong effect on bonding strength of titanium/porcelain, but some researchers pointed out that the strength of titanium bonding porcelain itself was too weak to inhibit the propagation of cracks and resulted in the lower bonding strength of titanium/porcelain than that of Ni-Cr/porcelain. So it is very necessary to develop a new titanium bonding porcelain that has better mechanical properities.According to protective mechanism and design rules, the major components of the titanium bonding porcelain were selected by considering the standard free energy of formation of the oxides, the wetting ability, viscosity, thermal expansion coefficient, mechanical property and chemical stability of porcelain. After the repeating test of soil phase reaction, a suitable porcelain (GGW bonding porcelain) was made. The GGW bonding porcelain was prepared via melting silicon oxide , boron oxide, aluminum oxide, sodium oxide, potassium oxide, baryta oxide and tin oxide et ail at 1400℃ and then quenched into water. The results of XRD showed that the GGW bonding porcelain contained cassiteriteoThe effects of sintering temperature on mechanical property of GGW bonding porcelain were studied. The results showed that a good integration property could be obtained at 800°Cwith the density of 2.74 g/cm3, the bending strength of 66.43±5.43MPa, Vicker hardness of 850.24±27.63MPa and fracture toughness of 4.18 MPa.m1/2. The bending strength and density were higher than those of VITA TITANKERAMIK。It is known that thermal coefficients of expansion, and the nature and strength of the bond are all factors that influence the ability of porcelain to resist fracture during clinical use of the restoration. The result of thermal expansion test showed that the GGW bonding porcelain had an ideal thermal compatibilitywith cast titanium between 25 ℃ to 500 ℃. The test of three-point bending bond strength according to ISO 9693 1999 showed that the bonding strength of GGW bonding porcelain /titanium (38.03±2.58MPa) had no statistical difference with that of Noritake Super Porcelain TI-22/titanium (39.41±0.86MPa) . SEM and EDS analyses of the surface of titanium side after the porcelain flaked off revealed that a large amount of crystals were formed at interface of titanium/porcelain; the structures of these crystals were benefitful to inhibit the propagation of cracks.In order to obtain a good bond between the titanium coping and the porcelain, it...