Objective: To evaluate the effect of different cement gap on microleakage of PMMA crowns cemented with resin cement.
Materials and Methods: Thirty natural human molar teeth were collected, the root of the teeth was sealed with a double layer of varnish for insulation to a level of 1 mm below the preparation margin, and mounted in an acrylic mold. Teeth were prepared through CNC, PMMA 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). PMMA 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 immersed in methylene blue dye solution for 24 hours, then sectioned buccolingually. Dye penetration was assessed using a spectromicroscope, and then a score assessment was done for the microleakage.
Results: The CG50 group scored the lowest median microleakage score, followed by CG100, and finally, CG25. The CG25 group; showed a statistically significantly higher median microleakage score than CG50 or CG100 groups. Conclusion: The cement gap has an effect on the microleakage of PMMA crowns cemented with self-adhesive resin cement.
Keywords: Cement gap, Microleakage, PMMA, Resin cement