Integration of CT, CAD system and finite element method to investigate interfacial stresses of resin-bonded prosthesis

Abstract

The question of whether prosthesis/abutment tooth interface debonding is associated with inappropriate occlusal force is investigated in this study. A new modeling approach was employed to perform the interfacial stress analyses. Solid models of resin-bonded (RB) prosthesis and abutment teeth were constructed by stacking serious section contours that were obtained from CT images. A 3-D finite element (FE) model of RB prosthesis/abutment teeth was generated in a CAD system after assembling and meshing procedures. An in-house program was developed to combine the FE package (ANSYS) to calculate the interfacial (normal and shear) stresses at the prosthesis/molar interface with the bonding and debonding conditions. After 10 different occlusal force(s) evaluations, three initial opening gaps at the distal margin of the retainer were assumed to examine the possible interface debonding mechanism under the worst loading case. The results indicated that a more accurate FE model of the posterior RB prosthesis/abutments could be generated through combining several computer-aided techniques. The maximum interfacial stresses were obtained when the occlusal force was applied on the buccal slope of the distolingual cusp of the molar. For interface debonding simulations, peak normal and shear stresses were found near the debonding areas and stress values increased gradually with small to large initial opening gaps. From these results, prosthesis/abutment tooth interfacial fatigue damage might arise or accelerate the interface to debond under adequate bonding or initial gap opening conditions after long-term repeated inappropriate occlusal force actions.