Fit of All-Ceramic Posterior Fixed Partial Denture Frameworks in Vitro

The objective of this study was to evaluate, by scanning electron microscopy, the marginal and internal fit of all-ceramic three-unit fixed partial denture (FPD) frames fabricated by computer-assisted design/computer-aided machining (CAD/CAM) and CAM techniques using blocks of infiltration ceramic, high-strength yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) zirconia sinter ceramic, high-strength dense sintered Y-TZP zirconia ceramic, and glass ceramic. Slip-cast infiltration ceramic was used as a traditional control. The cementation interface widths of the FPD frame copings on butt (A) shoulders of Cerec In-Ceram zirconia (A1, 53 ± 17 µm) were smaller than those of slip-cast In-Ceram zirconia (A6, 113 ± 25 µm). Cerec Y-TZP zirconia (A2, 53 ± 9 µm) and DCS Y-TZP zirconia (A4, 32 ± 6 µm) interfaces were both significantly smaller than those of Cercon Y-TZP zirconia (A5, 120 ± 6 µm). Internally, A2 (103 ± 14) interfaces were smaller than A4 interfaces (144 ± 15 µm). On chamfer shoulders (B), Cerec Y-TZP zirconia (B1, 71 ± 5 µm) interfaces were smaller than Cercon interfaces (B2, 129 ± 38 µm); internally, B1 (80 ± 11 µm) interfaces were smaller than B2 interfaces (130 ± 12 µm). CAD/CAM produced better marginal and internal accuracy of fit compared to slip casting and CAM techniques.