Fracture Load of CAD/CAMGenerated Slot-Inlay FPDs

Purpose: This study investigated fracture load of computer-aided design/manufacturing (CAD/CAM)-generated slot-inlay fixed partial dentures (FPD) machined from ceramic and composite. Materials and Methods: Ninety slot-inlay FPDs were machined in groups of 15 specimens each using the same design on a Cerec 3 unit. Materials were assigned to groups: (1)Mk II feldspathic ceramic, (2)ProCAD glass-ceramic, (3)glass-ceramic 1, (4) glass-ceramic 2, (5)composite 1, and (6)composite 2. The slot-inlay FPDs were placed on models with two abutment teeth without cementation and loaded to fracture. For control, test bars (n = 15) were machined from each of the materials, and flexural strength was examined using three-point bending. Data were statistically analyzed using ANOVA and Scheffé tests. Results: Fracture load of groups 4 (1,557 N, SD 236), 5 (1,048 N, SD 77), and 6 (1,512 N, SD 106) was significantly higher than that of groups 1 (652 N, SD 53) and 2 (773 N, SD 65). Flexural strength of group 4 (256 MPa, SD 20) was significantly higher than that of groups 1 (103 MPa, SD 6), 2 (127 MPa, SD 15), 3 (162 MPa, SD 32), 5 (178 MPa, SD 18), and 6 (170 MPa, SD 20). Conclusion: Fracture loads of glass-ceramic 2 and composite 2 appear adequate for CAD/CAM slot-inlay FPDs.