Effect of occlusal groove on abutment, crown thickness, and cement-type on fracture load of monolithic zirconia crowns.

The aim of this study was to investigate the effects of occlusal form of abutment, occlusal thickness of monolithic zirconia crowns (MZC), and cement type on the fracture load of MZC. Abutments were prepared with 2 types of occlusal forms: groove-type and flat-type. These were designed so that thickness at the central fissure region of MZC was 0.3, 0.5, or 0.7 mm. Glass ionomer cement and resin cement were used to lute MZC to their corresponding abutment. Fracture load was determined using a universal testing machine. As a result, groove-type abutment had lower fracture load compared to flat-type abutment; however, the decline in strength was smaller when resin cement was used. Additionally, specimens with larger occlusal thickness had greater fracture load regardless of groove or cement-type. The fracture of MZC occurred on the central fissure region of MZC except for 0.7 mm groove-type MZC luted with resin cement.