The impact of finish line design on the resistance to chipping of implants-based monolithic zirconia veneers

Abstract

Introduction: One of the major problems of all ceramic restorations is their probable fracture against the occlusal force. The aim of the present in vitro study is to compare the effect of two marginal designs (shoulder, chamfer) on the fracture resistance of monolithic zirconia crowns.

Materials & Methods: Two premilled abutments of the dio system were selected and customized by the abutment design software (Exocad). Then, the abutments are prepared and scanned by the arumm machine. The design of the covers was done by the software (Exocad). The veneer coordinates were transferred to the device and 8 premolar veneers were made on two abutments for the implant with a diameter of 5 mm. One of the abutments was prepared with a shoulder cut margin and the second abutment with a chamfer margin, and after scanning the data, they were transferred to the CAD-CAM machine (Laserdenta, Germany) to make the veneer.

Results: In this study, 8 samples were prepared and compared. The samples were divided into 2 chamfer (number = 4) and shoulder (number = 4) groups and were subjected to the force of 30 Newtons. The crack length in all samples was 551.025 ± 74.8 mm. There was no significant difference in the average crack length in both groups.

Conclusion: The result of this study indicates that shoulder marginal design causes increasing the fracture resistance of zirconia crowns.