CAD/CAM post-and-core using different esthetic materials: Fracture resistance and bond strengths

Purpose: To evaluate the fracture resistance (FR), and push-out bond strengths (BS) of custom-made CAD/CAM post-and-cores manufactured with different esthetic materials. Methods: 90 single-rooted extracted teeth were selected, endodontically treated and prepared to receive the posts. The specimens were randomly divided into three equal groups according to the material: hybrid ceramic Vita Enamic (HC); nano-ceramic resin composite Lava Ultimate (RC); and experimental epoxy-resin reinforced by glass-fiber (FG). The post-and-cores were manufactured using CAD/CAM and cemented using a self-adhesive resin cement (Rely X Unicem2). A subgroup of 30 specimens (n=10) was subjected to fatigue (1,000,000 cycles at 5 Hz) and then to the FR test. Another subgroup with 60 specimens was submitted to the BS test, with and without fatigue. Data were submitted to analysis of variance (FR - one-way ANOVA; BS - two-way ANOVA) and Tukey's test (alpha = 0.05). Results: The FR values (mean SD, in Newtons) were 414.5 +/- 83.9 (HC), 621.3 +/- 100.3 (RC), and 407.6 +/- 109.0 (FG), with RC showing significantly higher FR values (P< 0.05). For BS, there was no statistically significant difference among the materials, with and without fatigue (P> 0.05). The type of material used to obtain the CAD/CAM-customized post-and-cores had a significant effect on the FR, but not on the BS of the specimens. Fatigue did not influence the BS for the tested materials.