Interrupted ferrule/ post and core/ cast post and core/ zirconia post and core/ ferrule/ zirconia / CAD-CAM / CAD-CAM post and core / fracture resistance.Purpose: The aim of this study was to compare the fracture resistance ofendodontically treated teeth with interrupted ferrule using two types of postcore systems.Materials and methods: Forty extracted human maxillary central incisors were decoronated 2mm to the proximal cement-enamel junction and endodontically treated. Teeth were divided into two groups according to the type of restorative material (n=20), and then each group was subdivided into four subgroups according to the ferrule Cast ׃ continuity (n=5). Group1 post-core and metal ceramic crown. G1A: circumferential ferrule, G1L: ferrule interrupted labially, G1P: ferrule interrupted palatally and G1Px: ferrule interrupted proximally. Group2: CAD-CAM milled Zirconia postcore and all ceramic crown. G2A: circumferential ferrule, G2L: ferrule interrupted labially, G2P: ferrule interrupted palatally. G2Px: ferrule interrupted proximally. All samples were subjected to static load with a crosshead speed of 1mm/min at an angle of 135 degrees to the long axis of teeth until failure. Student t-test was used to detect significance between main groups. One way (ANOVA) test followed by pair-wise Tukey post-hoc tests were used to detect significance between subgroups.Results: Group1 recorded statistically significant higher mean fracture resistance values (271.775± 25.7 N) than Group2 (183.95 ± 12.6 N) (p<0.05). G1A recorded the highest statistically significant fracture resistance mean values (265.05 ± 58.2 N) followed by GPx (221.65 ± 35.57 N) then G1L (219.35 ± 35.15 N) while the G1P (205.4 ± 46.6 N) recorded the lowest fracture resistance mean values (p<0.05).Conclusion: Fracture resistance of teeth restored with a 2 mm circumferential ferrule was significantly greater than teeth with interrupted ferrule.