Titanium alloy cylinders in implant framework fabrication: a study of the cylinder-alloy interface

Titanium alloy has been proposed as a suitable alternative to noble metal alloys in premanufactured metal cylinders for fabricating implant prosthesis frameworks. The interfaces produced by standard lost wax procedures that use titanium and conventional noble metal implant cylinders with both high-fusing (high-palladium) and low-fusing (high-gold) noble metal casting alloys were compared. Elemental analysis by scanning electron microscopy and energy-dispersive spectroscopy (SEM/EDS) of the two titanium cylinders revealed that one commercial product had a composition similar to that for commercially pure titanium and the other had a composition consistent with that for Ti-6Al-4V alloy. The SEM observations and complementary elemental line scans indicated that the interfaces between the titanium cylinders and the two noble metal casting alloys did not meet proposed criteria for acceptable metal-to-metal unions. The interfaces between the noble metal cylinders and noble metal casting alloys did exhibit acceptable unions. The SEM observations and elemental analyses were supported by push-shear test results that showed that the resistance to failure was appreciably greater for interface specimens produced with alloy cast to noble metal cylinders compared with titanium cylinders.