Fracture Strength of Surface Treated Zirconia Based Multilayer CAD/CAM Ceramic Crowns

Abstract

Objective: The purpose of this study was to evaluate the effect of different surface treatments on the fracture strength of veneered zirconia crowns designed by multilayer technique. Material and Methods: Thirty zirconia cores (Sirona inCoris ZI) were constructed (inLab 4.4) on metal dies. Zirconia cores were divided into three groups: sandblasting with 30 pm silica-coated aluminum oxide particles (Group C), sandblasting with 50 pm aluminum oxide particles (Group K) and sandblasting with 50 pm aluminum oxide particles then silica coating with Silano-Pen (Group KS). Thirty feldsphatic ceramic (VITABLOCS Mark II) veneers were fabricated (inLab 4.4). Veneers were cemented to the cores. Crowns were cemented to the metal dies. A universal test machine was used for the fracture strength test at a crosshead speed of 1 mm/min. The data were analyzed with one-way ANOVA (a=0.05). Results: Surface pre-treatment methods affected the fracture strength (p<0.05). Higher fracture strengths were obtained in Group KS (p<0.05). No significant differences were found between Group K and Group C (p>0.05). Conclusion: Although Group K and C showed lower flexural strength, it was higher than the maximum loads which may occur clinically (Fmax=600N on one tooth). Also, Silano-Pen application is advisable for increasing the fracture strength. Clinical Relevance: The multilayer zirconia crowns can be applied successfully, especially in single-crown restorations. (English) [ABSTRACT FROM AUTHOR]