The shear stress distribution of two different cantilever RBFPDs

Objectives: The purpose of this study was to evaluate the shear stress distribution of adhesive resin cements with different framework-design using three-dimensional finite element analysis (FEA).
Methods: The human dry skull with maxillary central incisor and canine was scanned with a micro focus computed tomography (micro-CT), and constructed into three dimensional image which lateral incisor was missing. After 3D construction, the model was produced by resin material.
The maxillary central incisor and canine were prepared for resin-bonded fixed partial dentures (RBFPDs).
Two types of RBFPDs frameworks were produced using acrylic resin: two cantilever RBFPDs using central incisor or canine for the abutment tooth.
Micro-CT scan was performed for each frameworks set on the model, and scanned images were converted to Digital Imaging and Communication in Medicine format. The thickness of the cement space was 120 µm from the adherent surface of the abutment teeth.
FEA was performed to measure the shear stress between the cement layer and zirconia frame of RBFPDs. the analysis was performed on the computer softwere with the following condition; stress of 200 N at 45 degree to palatal surface of the pontic.
The volume of adhesive resin cements, which the shear stress applied 11 Mpa (allowable shearing stress of the PanaviaF2.0 ) and over, was picked up to evaluate the risk of debonding.
Results: The volume-percentage of adhesive resin cements of two cantilever RBFPDs using central incisor and canine for the abutment tooth, which the shear stress (>11 Mpa) applied to, were 19.25 % and 23.44 %, respectively.
Conclusions: In this study, the volume-percentage of adhesive resin cements in the cantilever RBFPDs using central incisor, which were applied the shear stress (>11 Mpa) was smaller than using canine.