Aim: The purpose of this invitro study was to evaluate and compare the marginal gap of CAD CAM crowns milled from two ceramic materials.
Materials and methods: Sixteen natural sound upper first molars were prepared for full coverage crowns using computer numerical control (CNC) .CAD CAM all ceramic crowns were fabricated and seated to the corresponding molars. Samples were divided into two groups according to the ceramic material ; group (E): Emax CAD ( Lithium disilicate glass ceramics ) (n=8), group (V): Vita suprinity( Zirconia reinforced lithium silicate ceramic ) (n=8). Vertical marginal gap of all samples was measured by digital microscope.
Results: Emax CAD group ( Lithium disilicate glass ceramics )showed significantly higher marginal gap values (M=95.4, SD=8.27) in comparison with Vita suprinity group ( Zirconia reinforced lithium silicate ceramic ) (M=75.47, SD=8.9).
Conclusions: Marginal gap values were within the clinically acceptable range where full coverage Emax CAD crowns revealed higher gap values than Vita suprinity crowns.