Purpose: In an attempt to improve the mechanical properties, industrially
CAD/CAM ceramics blocks have been introduced to dentistry. This study was directed to investigate the influence of the material thickness on the fracture resistance of
CAD/CAM Resin Ceramic and CAD/CAM Ceramic and asses the fatigue resistance of class II mesio-occlusal-distal (MOD) inlays of both materials and compare their micro-tensile bond strength (μTBS) after cementation by two different adhesive resin cements. Materials and Methods: A total of 70 specimens were fabricated. The specimens were divided according to the material used into two main groups (n= 35). Group 1 specimens were fabricated from CAD/CAM Resin Ceramic (Vita Enamic), whereas Group 2 specimens were fabricated from Lithium disilicate glass ceramic (IPS e-max CAD). Specimens of each group were further subdivided into 3 subgroups according to type of testing (microtensile bond strength test, fracture resistance and fatigue resistance tests). Specimens of subgroup of microtensile bond strength test (n=40) were further subdivided into 2 divisions (n=20) according to type of surface treatment (control and sandblasting). Then each division was further subdivided into 2 subdivisions (n=10) according to type of cement used (Rely X Ultimate and multilink N). Furthermore, subgroup of fracture resistance test (n=20) was further divided into 2 division (n=10) according to thickness (0.5 mm and 3 mm). Two-way analysis of variance ANOVA test and three-way analysis of variance ANOVA test of significance were done for comparing variables. Results: For microtensile bond strength, it was found that the highest μ-tensile bond strength value was recorded for Multilink N control subgroup (54.07±7.9 MPa), while the lowest μ-tensile bond strength mean values was for Rely X Ultimate sandblasted subgroup (37.12±2.5 MPa) and IPS e-max CAD. Results revealed that the highest μ-tensile bond strength mean value was recorded for Rely X Ultimate