Effect of Vent Hole and Cement Type on Fracture Resistance of CAD‐CAM Monolithic Zirconia Crowns

Abstract Purpose To assess the fracture resistance of monolithic zirconia crowns cemented with different types of cement on cement‐retained implant abutments. Materials and methods Forty implant analogs were positioned in acrylic resin blocks, and cement‐retained straight implant abutments were fastened to the analogs. Crowns were designed with/without occlusal vent holes and produced from monolithic zirconia blocks by the CAD‐CAM technique. The two crown types were divided into two groups and cemented with resin and zinc‐polycarboxylate cement under 5 kg weight. A universal testing machine applied compressive forces to the crowns until fracture. Fracture resistance values were analyzed using two‐way ANOVA and the independent samples t ‐test with statistical significance set at p < 0.05. Results According to the two‐way ANOVA results, although the crown design did not have a significant effect on fracture resistance (1417.65 ± 337.39 N, 1565.16 ± 517.12 N; crowns with and without vent holes, respectively), the main effect of the cement variable on the fracture resistance was significant. Zinc‐polycarboxylate cement (1680.1 ± 375.23 N) showed higher fracture resistance than resin cement (1302.71 ± 420.64 N) in the crowns designed with vent holes ( p < 0.005). Conclusion The use of cement‐retained implant‐supported monolithic zirconia crowns with an occlusal vent hole is safe, and zinc‐polycarboxylate cement use may be an appropriate choice for cementation of these crowns.