In Vitro Static and Fatigue Behavior of Ceramic Occlusal Veneers Using CAD/CAM

To evaluate fracture resistance of occlusal veneers made of glass-ceramic and zirconia with and without fatigue. Occlusal overlays (N.80; n=10 per group) were milled out of CAD/CAM materials, namely: a)D:Lithium disilicate glass ceramic, b)LDS:Lithium-disilicate-strengthened aluminosilicate glass ceramic, c)ZLT:Zirconium dioxide ceramic and d)ZMT:Zirconium dioxide ceramic. The overlays were cemented on polymeric duplicates, randomly distributed to aging or non-aging conditions and loaded until fracture. Ultimate catastrophic failure strength(F-max) and initial crack formation load(F-initial) values were analysed using two-way ANOVA. For F(initial )material type and aging and their interaction resulted in significant values (p= <0.001). F-initial mean +/- SD values ranged from ZMTa (593 N +/- 205 N) to LDSb (118 N +/- 142</span> N). As for F-max,, the material type significantly affected the outcome (p<0.000, while aging type did not show an influence (p=0.795). The non-aged F-max specimens values presented were: LDSa (877N +/- 253 N)<LDa (2029 N +/- 412 N)<ZLTa (2049 N +/- 379 N)<ZMTa (2144 N +/- 333 N), LDSa being significantly lower (p<0.001). The aged F-max values were: LDSb (1313 N +/- 599 N)< ZLTb (1715 N +/- 453 N)<ZMTb (2018 N +/- 300N)<LDb (2134 N +/- 289 N). LDS yielded significantly lower F-max values without and non-significant less favourable results with aging. The mechanical properties following aging and lack of additional firing makes LOS an interesting restorative material for clinical application.