Zirconia-based dental crown to support a removable partial denture: a three-dimensional finite element analysis using contact elements and micro-CT data

Veneer fracture is the most common complication in zirconia-based restorations. The aim of this study was to evaluate the mechanical behavior of a zirconia-based crown in a lower canine tooth supporting removable partial denture (RPD) prosthesis, varying the bond quality of the veneer/coping interface. Microtomography (μCT) data of an extracted left lower canine were used to build the finite element model (M) varying the core material (gold core – M_Au; zirconia core – M_Zi) and the quality of the veneer/core interface (complete bonded – M_Zi; incomplete bonded – M_Zi-NL). The incomplete bonding condition was only applied for zirconia coping by using contact elements (Target/Contact) with 0.3 frictional coefficients. Stress fields were obtained using Ansys Workbench 10.0. The loading condition (L = 1 N) was vertically applied at the base of the RPD prosthesis metallic support towards the dental apex. Maximum principal (σ_max) and von Mises equivalent (σ_vM) stresses were obtained. The σ_max (MPa) for the bonded condition was similar between gold and zirconia cores (M_Au, 0.42; M_Zi, 0.40). The incomplete bonded condition (M_Zi-NL) raised σ_max in the veneer up to 800% (3.23 MPa) in contrast to the bonded condition. The peak of σ_vM increased up to 270% in the M_Zi-NL. The incomplete bond condition increasing the stress in the veneer/zirconia interface.