Objective: The aim of this study was to assess the fracture resistance of zirconia-reinforcedceramic crowns depending on different ceramic thicknesses.
Material and Methods: Mandibular first molars were used for crown restorations in a typodont model with CEREC system. Samples (n=12 each) were fabricated by using two zirconia-reinforced lithium silicate (ZLS) ceramic materials (VITA Suprinity, Celtra Duo) and zirconia reinforced alumina ceramic (ZLA) (In-Ceram Zirconia) with thicknesses 1.0 and 1.5 mm. Fractural and thermomechanical loading tests were performed. One-way variance analysis test (ANOVA) and post-hoc Scheffé tests were used for analyzing the results.
Results: Fracture strength values were statistically significantly influenced by material thickness (p<.001), but not material type. Strength values were significantly higher for 1.5 mm thickness materials than 1.0 mm samples (p<.001).
Conclusions: CAD/CAM crowns showed acceptable fracture strength values which were above clinically expected loadings. Zirconia-reinforced ceramic materials with1.5 mm thickness may be a good choice for crown restorations in daily clinical practice.