Passivity and Misfit of Frameworks Obtained by Different Methods

Objectives: To evaluate the passivity and vertical and horizontal misfit of fixed partial dentures (FPDs) with distal cantilever screwed on two implants and CoCr frameworks obtained by conventional casting and CAD/CAM system.
Methods: Thirty CoCr frameworks were obtained and distributed in 3 groups (n=10), according to obtaining method: G1 – conventional casting (Laser welding); G2 – conventional casting (TIG welding) and G3 – CAD/CAM system. After ceramic veneering application by pressed technique on frameworks, the passivity and vertical and horizontal misfit were analyzed by confocal laser scanning microscopy, using the Sheffield method. Passivity and misfit were assessed using Shapiro-Wilk test and ANOVA with Bonferroni post-hoc test was used to compare the groups.
Results: A significant difference (p<0.001) in the horizontal misfit was observed between FPDs with frameworks obtained by the conventional cast (G1 and G2) and CAD/CAM system (G3), where G1 and G2 presented sub extension and G3 overextension cervical. In addition, the passivity of the G1 was significantly lower than G2 (p=0.017) e G3 (p=0.005) only in premolar with a non-tightened screw.
Conclusions: Within the limits of this study, conventional cast associated with laser welding was more effective as a technique to improve passivity and vertical misfit.