Scanning electron microscope evaluation of marginal discrepancy of gold and base metal implant-supported prostheses with three fabrication methods

Abstract

Background : Marginal discrepancies in implant-supported prosthesis are inevitable, despite careful waxing, investing, and casting procedures. The choice of metal also affects these discrepancies. Materials and Methods : A total of 48 frameworks were fabricated: 16 made with the Burn-out Coping (group 1), 16 made with Impression Coping (group 2) and 16 with conventional wax-up technique (group 3). Each group was divided into two subgroups, based on the metal alloy used. Eight of the specimens in each group were fabricated with noble alloy (Begostar, Bego, Bremen, Germany) (groups 1n, 2n and 3n) and the other eight with base metal alloy (Verabond 2, Albadent, Cordelia, California) (groups 1b, 2b, and 3b). All specimens were waxed on the analogue abutments and cast. After fixing and embedding, the specimens were sectioned and prepared for scanning electron microscope (SEM) evaluation. Frameworks were analyzed for vertical and horizontal discrepancies with ×200 magnifications. Data were analyzed statistically by multivariate analysis and post hoc tests (α=0.05). Results : The vertical discrepancy measurements for noble groups (1n, 2n and 3n) were significantly less than those of the base metal alloy groups (1b, 2b and 3b) ( P .05), waxing the frameworks with impression copings significantly increased the horizontal discrepancy at the interfaces (groups 2n and 2b) ( P <.001). Conclusions : Vertical discrepancies of the frameworks made with proposed techniques were comparable with each other. Noble alloy frameworks produced more horizontal and less vertical discrepancies.