Biomechanical behavior of CAD/CAM cobalt-chromium and zirconia full-arch fixed prostheses

To verify the influence of computer-aided design/computer-aided manufacturing (CAD/CAM) implantsupported prostheses manufactured with cobalt-chromium (Co-Cr) and zirconia (Zr), and whether ceramic application, spark erosion, and simulation of masticatory cycles modify biomechanical parameters (marginal fit, screw-loosening torque, and strain) on the implant-supported system.MATERIALS AND METHODS.Ten full-arch fixed frameworks were manufactured by a CAD/CAM milling system with Co-Cr and Zr (n=5/group).The marginal fit between the abutment and frameworks was measured as stated by single-screw test.Screw-loosening torque evaluated screw stability, and strain analysis was explored on the implant-supported system.All analyses were performed at 3 distinct times: after framework manufacturing; after ceramic application in both materials' frameworks; and after the spark erosion in Co-Cr frameworks.Afterward, stability analysis was re-evaluated after 10 6 mechanical cycles (2 Hz/150-N) for both materials.Statistical analyses were performed by Kruskal-Wallis and Dunn tests (α=.05).RESULTS.No difference between the two materials was found for marginal fit, screwloosening torque, and strain after framework manufacturing (P>.05).Ceramic application did not affect the variables (P>.05).Spark erosion optimized marginal fit and strain medians for Co-Cr frameworks (P<.05).Screwloosening torque was significantly reduced by masticatory simulation (P<.05) regardless of the framework materials.CONCLUSION.Co-Cr and Zr frameworks presented similar biomechanical behavior.Ceramic application had no effect on the biomechanical behavior of either material.Spark erosion was an effective technique to improve Co-Cr biomechanical behavior on the implant-supported system.Screw-loosening torque was reduced for both materials after masticatory simulation.