Vertical and Internal Discrepancies of Cerec Ceramic Crowns

Objectives: This study evaluated the marginal (MD) and internal (ID) discrepancies of ceramic crowns manufactured by the CAD/CAM system Cerec inLab, varying the finish line. The null hypothesis was that the preparations won't influence the MD and ID of the crowns. Methods: From three metallic dies with different finish lines, thirty ceramic crowns (ProCad/Ivoclar Vivadent) were machined (n=10): TC) tilted chamfer; LC) large chamfer and RS) rounded shoulder. For MD analysis, were measured, in 50 points, the distance between each crown extern edge to the edge of the cervical preparation on the respective metallic die. Using the replica technique, it was evaluated the ID of each crown at 12 points equally distributed between the regions: end (E), axial (A) and oclusal (Ocl). The mensurations were done in optical microscope (250x). The data obtained (µm) were submitted to the statistical tests ANOVA and Tukey (5 %). Results: The group RS (28,24 ±11,42 µm) produced MD values smaller (p=0,001) than the groups TC (99,92±18,32 µm) and LC (64,71±25,64 µm), which, between them, differed statistically. The analysis of ID demonstrated that the group LC (183,01±62,82 µm) presented values lower (p=0,0014) than TC (216,26±83,23 µm) and RS (219,12±87,24 µm), which were similar between them. It was also noticed that ID varied between the measured regions (p=0.0001). The null hypothesis was rejected. Conclusion: In spite of the statistical differences observed between the groups, the three cervical finish lines produced crowns with MD and ID values clinically acceptance.