Application of titanium alloys to porcelain fused to metal crown

钛具有优良的性能，是一种很有吸引力的牙科修复材料，但铸造困难。β稳定钛合金的熔化温度低于纯钛。对于牙科临床应用，由于牙科美学的要求，这些合金必须能够粘结到牙科瓷器上。测试了18种二元钛合金：钛铬(15，20，25wt%)，钛-钯(15，20，25wt%)，钛-银(10，15，20wt%)，钛-铜(5，10wt%)，钛-铁(5，10，15wt%)和钛-锰(5，10，15，20wt%)。作为对照，还检查了纯钛和一种金合金。结合强度根据ISO 9693进行评估。还测量了每种材料的弹性模量。钛合金成分对合金弹性模量有显著影响，但对烤瓷结合强度影响不大。所有实验合金的结合强度都与两种对照合金(纯钛和金合金)相似，均高于ISO 9693规定的最低值25兆帕。这些结果表明，实验合金具有足够的剪切粘结强度用于金属-陶瓷修复。在本研究中，一些试件(Ti-15wt%Pd和Ti-20wt%Pd)在冷却时发生偏转，即使在粘结测试之后也是如此。这些合金的热膨胀值与其他合金相差不大。下一项研究通过分析热膨胀/收缩曲线来研究这种变形的原因，由于β-α相变和瓷器收缩产生的应力同时发生，这些合金永久变形(即它们经历了蠕变)，导致试件变形。

Titanium is an attractive dental restorative material because of its excellent characteristics, however it is difficult to cast. Beta-stabilized titanium alloys have lower fusion temperatures than pure titanium. For dental clinical use, these alloys must be able to bond to dental porcelains because of the esthetic demands of dentistry. Eighteen binary titanium alloys were examined : Ti-Cr (15, 20, 25 wt%), Ti-Pd (15, 20, 25 wt%), Ti-Ag (10, 15, 20 wt%), Ti-Cu (5, 10 wt%), Ti-Fe (5, 10, 15 wt%) and Ti-Mn (5, 10, 15, 20 wt%). As controls, pure titanium and a gold alloy were also examined. Bond strengths were evaluated according to ISO 9693. The elastic modulus was also measured for each. The titanium alloy composition had a significant effect on alloy elastic modulus, but it had little effect on the bond strength to porcelain. The bond strengths for all the experimental alloys were similar to those of the two control alloys (Pure titanium and gold alloy) and were higher than 25 MPa, the minimum value specified in ISO 9693. These findings indicate that the experimental alloys exhibited sufficient shear bond strength for use in metal-ceramic restorations.In this study, some specimens (Ti-15wt%Pd and Ti-20wt%Pd) deflected upon cooling, even after the bond test. The thermal expansion value of these alloys was not much different from that of the other alloys. The next study investigated the cause of this deflection by analyzing the thermal expansion/shrinkage curve.Because the beta to alpha phase transformation and the stress developed from the shrinkage of the porcelain simultaneously occurred, these alloys were permanently deformed (I.e., they underwent creep), resulting in the deflected specimens.