Flexural strength of various types of computerized machinable ceramic veneered to yttria stabilized tetragonal zirconia polycrystalline ceramic upon different hybridized techniques

Objective: This study determined biaxial flexural strength (BFS) of computer-aided design/computer-aided manufacturing (CAD/CAM) ceramic veneered yttria-stabilized tetragonal zirconia poly-crystalline (Y-TZP) related with hybridization techniques and veneering materials. Material and methods: One hundred and twenty zirconia Y-TZP (0.8 mm thick and 12 mm in diameter) were prepared and randomly divided into eight groups, to be conjugated with different veneering ceramics: Vitabloc (Vm), e.max-CAD (Em), Vita-Suprinity (Vs) and Celtra-Duo (Cd), using different hybridized techniques, CAD-bonded (Cb) versus CAD-fused (Cf). BFS was determined using piston on three balls and analyzed for Weilbull reliability. An analysis of variance (ANOVA) and Bonferroni’s multiple comparisons were determined for significant differences. Microscopic structures were examined with scanning electron microscope (SEM), along with X-ray diffraction (XRD). Results: BFS (mean±sd; MPa), Weibull modulus (m), and characteristic strength (σ(o)) of each group were 630.46±65.08, 10.72, and 659.47 for VmCb, 709.03±102.88, 7.67, and 753.03 for VmCf, 651.83±69.48, 9.47, and 685.82 for EmCb, 721.17±121.28, 5.99, and 777.04 for EmCf, 692.83±89.10, 8.56, and 731.87 for VsCb, 888.61±164.26, 5.80, and 959.08 for VsCf, 687.17±59.39, 12.85, and 713.95 for CdCb, and 953.12±134.30, 7.97, and 1010.65 for CdCf. The BFS of ceramic veneered zirconia were significantly affected by different veneering ceramics, hybridized techniques, and their interactions (p<0.05). Cd showed highest BFS, followed by Vs, Em and Vm respectively. Both Cd and Vs showed significant higher BFS than Em and VM (p<0.05). No significant difference of BFS between Cd and Vs and between Em and Vm were indicated (p>0.05). Cf technique showed significantly higher impact on BFS than Cb (p<0.05). Veneering zirconia with either Cd or Vs using Cf technique revealed significantly higher flexural strength than others combinations (p<0.05). Conclusions: Type of veneering ceramics and hybridization techniques affected BFS of ceramic veneered Y-TZP. Veneering zirconia with either Cd or Vs using Cf-process produced superior BFS.