Comparison of fracture resistance of monolithic thin-walled and full-contour zirconia crowns

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Comparison of fracture resistance of monolithic thin-walled and full-contour zirconia crowns

Journal Title: Prosthodontics - Year 2016, Vol 66, Issue 1

Abstract

Introduction. Monolithic full zirconia crowns become a alternative for conventional zirconiabased ceramic crowns for restoration of posterior teeth. This kind of restoration requires more conservative teeth preparation, moreover, there are no complications, such as ceramic chipping. The crowns are made of more translucent zirconium oxide to ensure acceptable esthetics. However, there are no evidence how the changes in the structure of monolithic zirconia influence the strength.Aim of the study. To investigate the fracture strength of thin-walled and full-contour crowns made of zirconium dioxide.Materials and method. Forty zirconium oxide crowns, divided into 4 groups of 10 samples each, were used in strength investigations. Crowns were made of conventional zirconium dioxide (Ceramill Zi, Amman Girrbach): group CZi ─ thin-walled (thickness, 0.5 mm), group FZi – fullcontour (thickness – 1.5 mm), and translucent zirconium dioxide (Ceramill Zolid, Amman Girrbach): group CZol ─ thin-walled and group FZol – full-contour. The crowns were fabricated using the CAD/CAM method. Fracture resistance tests were performed with universal testing machine (Zwick Roell Z020), using 3.5 mm ballshape head. The graphs demonstrating force to deformation function were recorded for all the samples. The results were subjected to statistical analysis. The investigation was filmed, and then the failure analysis was done.Results. The mean fracture strength was recorded for group FZi, 1290±33 N, group FZol,1180±19.9 N, group CZi, 409±34.3 N and group CZol, 319±30.4 N. The difference between the mean fracture strength values for fullcontour and thin-walled crowns was statistically significant. The main pattern of crown failure (70 %) was the spot damage on the occlusal surface with axial walls intact.Conclusion. The ceramic crowns made of translucent zirconium dioxide demonstrated a lower fracture resistance than the crowns made of conventional zirconium dioxide. The fracture strength of monolithic zirconium crowns depends on their thickness. The thicker are the walls of the crowns the higher is the fracture resistance.

Authors and Affiliations

Beata Dejak, Cezary Langot, Michał Krasowski, Bartłomiej Konieczny

Keywords

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EP ID EP80067
DOI -
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