Document Type : Original Articles

Abstract

Introduction: One of the main problems in stress analysis of new prosthesis materials stems from their unpredictable shape. The aim of this study was to determine the effect of adhesives and ligament on stress distribution in cantilever and fixed-end prostheses. Materials and methods: In the present study, finite element analysis was used to prepare physical models from natural teeth. Then three-dimensional images were prepared from the finite element model and the relevant prostheses. The finite element was prepared to apply the proper load and boundary conditions, followed by calculation of shear and von Mises stresses along with displacements in teeth, adhesives and prostheses. Results: In the fixed-end prosthesis the Z100 adhesive exhibited the highest von Mises stress value, which increased with an increase in the adhesive elastic modulus. Panavia 2 adhesive ranked the second after Z100 adhesive. Variolink and C&B adhesives exhibited less von Mises stresses under the same loading condition. Elimination of ligaments resulted in an 0.2% increase in the shear stress in Panavia 2 and Z100. In the cantilever prosthesis, the Z100 adhesive still exhibited the highest stress value, with Panavia 2 ranking the second. Elimination of ligaments in the cantilever prosthesis resulted in a slight decrease in von Mises stresses in all types of adhesives, contrary to fixed-end prosthesis. The effect of ligaments on the displacement of the cantilever prosthesis was more than that on the fixed-end prosthesis. Conclusion: Based on the results, there were less stresses in fixed-end prosthesis compared to cantilever prosthesis. Although the shear and von Mises stresses were higher in Panavia 2 and Z100 adhesives compared to Variolink and C&B, due to their Poisson’s ratios and elastic moduli, which were close to those of the dentin, they produced less displacement in the prostheses.  Key words: CT scan, Finite element analysis, Prosthesis design.