An evaluation of the compressive strength of zirconia crowns fabricated with various tooth preparation finish lines using a CAD/CAM system

INTRODUCTION. In clinical dentistry, fixed prosthetic restorations, especially those composed completely of zirconia – are frequently utilized to restore natural teeth. The design of the tooth preparation, particularly the finish line type, and the restoration’s resistance to occlusal forces during mastication are critical factors in its effectiveness. AIM. This in vitro study aimed to assess the impact of two gingival finishing lines (45° chamfer and 90° shoulder) on the compressive strength resistance of complete contour zirconia CAD/CAM all-ceramic crowns. MATERIALS AND METHODS. All sixteen lower primary molars were prepped to receive full contour CAD/CAM ceramic crowns utilizing a sophisticated paralleling equipment. Based on the kind of finishing line that was planned, the teeth were split into two groups. group A prepared with 90° shoulder finish line and group B prepared with 45° chamfer finish line. Materials are tested for compressive strength using a universal testing machine. RESULTS. The data analysis manifested that, shoulder and chamfer margins of zirconia crowns showed that the mean compressive strength resistance of chamfer margin is 5287.50N and the shoulder margin is 3200.00N. The statistically significant difference between the groups and compressive strength of chamfer margin was more than shoulder margin. CONCLUSIONS. The study’s findings suggested a connection between the finishing line’s design and the entire CAD/CAM zirconia crowns’ compressive strength.