Removable partial denture supported by zirconia-based crown. Mechanics of veneer

Objectives: The aim of this study was to evaluate the mechanical behavior of a zirconia based total crown in a mandibular canine for supporting a removable partial denture. The bond at the veneer/zircornia coping interface varied between perfect and partially bonded conditions. Methods: The µCT data of a left extracted mandibular canine was used to build the finite element model (M) varying the material of the coping (MAu – gold coping and MZi – zirconia coping) and the bond at the venner/coping interface (MZi – perfect bonded and MZi-NL – partially bonded). The partially bonded condition was applied just for zirconia copings by using contact elements (Target/Contact) with frictional coefficient of 0.5. The stress fields were obtained by using Ansys Workbench 10.0. The loading condition (L=1N) was vertically applied at the base of the metallic support of the RPD towards dental apex. The maximum principal stress (σmax) and the von Mises equivalent stress (σvM) were obtained. Results: The σmax (MPa) for the bonded condition was similar between gold and zirconia copings (MAu = 0.42, MZi = 0.40). The partially bonded condition (MZi-NL) raised the σmax in the veneer up to 800% (3.23 MPa) in comparison with the bonded condition. The peak of σvM raised up to 270% for the MZi-NL. Conclusion: Considering the failure scenario at the veneer/coping interface, the veneer showed high risk of failure under the loading condition simulated in this study. (Fapesp #2008/00209-9)