Casting accuracy of titanium frameworks for implant-fixed partial dentures

Objective: Titanium frameworks are frequently used for implant fixed partial dentures (FPD) on the concept of one-metal rehabilitation. This study evaluated the casting accuracy of titanium frameworks for implant-FPD with a fully formed hybrid composite (Ti-FPD). Methods: Forty-seven implant-fixed superstructures were fitted to 40 patients between February 2005 and December 2007. The frameworks were cast with commercially pure (CP) titanium grade III (T-alloy H, GC) using a GC Autocast system. After priming a bonding agent (Metal primer II, GC), a hybrid prosthetic composite (Estenia, Shofu) was fully applied to a titanium framework. Before cementing the Ti-FPDs, marginal and internal fits were recorded intraorally to record the gap between the titanium framework and abutment using white and black silicone impression materials (Fit Checker and Bite Checker, respectively, GC) according to the previous study (Euro J Prosthodont Res Dent 14: 85-89, 2006). The marginal and axial wall film thickness was measured microscopically (Profile Projector V-16E, Nikon) at 50x magnification. As controls, Ag-Au-Pd alloy and Type IV gold alloy frameworks of FPD were measured. Data were statistically analyzed by ANOVA/Tukey's test (a=0.05). Results: There was no statistical difference of the mean marginal and axial wall gaps among the cast titanium (marginal 52µm, axial 87µm), Ag-Au-Pd alloy (marginal 68µm, axial 88µm), and Type IV gold alloy (marginal 71µm, axial 95µm) (p>0.05). No clinical problems resulting from using titanium for implant FPDs were observed. Conclusions: The casting accuracy of titanium frameworks was clinically accepted. No clinical disadvantages of cast titanium frameworks were evident during short-term observations.