Crystallization firing effect on the marginal discrepancy of the IPS. emax CAD crowns using two different CAD/CAM systems

Background: Marginal adaptation is critical for long – term success of crown and bridge restoration. Computer aided design / computer manufacture (CAD/ CAM) system gaining more importance in the fabrication dental Objective: The aim this study to evaluate effect crystallization firing on vertical marginal gap IPS. emax CAD crowns which fabricated with two different CAD/CAM systems .Materials Methods: Twenty IPS e.max were fabricated. We had major groups (A, B) (10 each group) according being used: Group A: Imes - Icore system; B: In Lab Sirona system. Each group was subdivided into subgroups pre-crystallized (Group A1, B1) crystallized A2, B2). At four points aspect crown, gaps assessed master metal die by using digital microscope at a magnification (110X) image- J program. measurement done twice crown; before after process.Results: lowest mean (29.387±2.774μm) (70.108±5.569μm) respectively A (Imes system) highest value (51.728 ±3.774μm) (84.071 ±4.567μm) B (Sirona system). Paired sample t-test result showed statistically highly significant difference between all groups.Conclusions: process increases gap. lower than have an acceptable