Effect of Cement Gap on the Retention of Zirconia Crowns

Abstract

Objective: To evaluate the effect of different cement gap on retention of zirconia crowns cemented with resin cement. Materials and methods: Thirty sound natural human molar teeth were collected and mounted in an acrylic mold. Teeth were prepared through a Computerized Numerical Control CNC, and then zirconia crowns fabricated by cad/cam. Samples were divided into 3 subgroups according to the cement gap(CG) (n=10): 25µm (CG25), 50µm (CG50), 100µm (CG100). Zirconia crowns cemented with Breeze Self-Adhesive Resin Cement. Samples were thermocycled for 5000 cycles between two water baths at 5°C and 55°C with a dwell time of 20 seconds and 10 seconds of transfer time. Samples were subjected to tensile test using universal testing machine, dislodgment force recorded in MPa. Results: No significant difference was found between mean pull-out bond strength at different cement gaps. Conclusion: The cement gap did not affect the retention of zirconia crowns cemented with resin cement.