MARGINAL ADAPTATION OF CAD / CAM OCCLUSAL VENEERS FABRICATED FROM DIFFERENT MATERIALS WITH TWO DIFFERENT THICKNESSES:(AN IN-VITRO STUDY)

Purpose: The purpose of this study was to compare the marginal adaptation of occlusal veneers constructed from lithium disilicate (IPS e-max), Zirconia reinforced lithium silicate (Celtra Duo) and Resin matrix ceramics (Shofu) materials with two restoration thicknesses.Materials and Methods: 42 Human 2nd mandibular molars were fixed into epoxy resin transparent blocks. Teeth preparation for occlusal veneer was done with 0.5 mm chamfer finish line. Samples were randomized equally into 3 groups according to the material: group 1: (IPS e-max CAD), group 2: (Celtra Duo) and group 3: (Shofu Hc). Samples were further subdivided into 2 groups of thickness: subgroup (A) conventional 1.5mm and subroup (B) thin 1mm. Designing was done by Cerec 3D software version 4.5 with omnicam intraoral scanner. CEREC MCXL 4-Axis machine was used for milling of occlusal veneers. Each surface of the occlusal veneer restoration was subjected to stereomicroscope for testing marginal adaptation. Results: The mean marginal gap of tested samples showed the highest marginal gap for thin thickness of IPS E-max CAD group (12.74 ± 3.8μm), and the lowest marginal gap for conventional thickness of Celtra Duo group (7.69 ± 4.24) μm). Comparison between the two tested thicknesses showed non-significant difference as P>0.05. Comparison between the different materials showed significant difference as P<0.05. Conclusion: Celtra Duo group showed the highest marginal adaptation and IPS E-max CAD showed the lowest marginal adaptation. Both conventional and thin occlusal veneer thickness of the three tested materials presented marginal adaptation mean values within the clinical accepted range.