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)LD: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(Fmax) and Initial crack formation load(Finitial) values were analysed using two-way ANOVA. For Finitial, material type and aging and their interaction resulted in significant values (p =⟨0.001). Finitial mean±SD values ranged from ZMTa (593 N ±205 N) to LDSb (118 N ±42 N). As for Fmax, the material type significantly affected the outcome (p⟨0.001), while aging type did not show an influence (p=0.795). The non-aged Fmax specimens values presented were: LDSa (877 N ±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 Fmax values were: LDSb (1313 N ±599 N)⟨ ZLTb (1715 N ±453 N)⟨ZMTb (2018 N ±300 N)⟨LDb (2134 N ±289 N). LDS yielded significantly lower Fmax values without and non-significant less favourable results with aging. The mechanical properties following aging and lack of additional firing makes LDS an interesting restorative material for clinical application.