PHOTOELASTIC AND FINITE-ELEMENT STRESS ANALYSIS OF A RESTORED AXISYMMETRIC FIRST MOLAR

First molars with full gold crown preparations and a shoulder geometry were idealized by an axisymmetric model and analyzed by the photoelastic, as well as the finite element method. The photoelastic model was constructed in two pieces, the restoration and the tooth with the preparation. The two pieces were then luted together and the model was loaded axisymmetrically with 100lb; it was stress frozen, sliced, and analyzed with the help of a polariscope. The finite element model was subdivided into 348 elements. The radial and axial stresses were plotted as a function of the radius along various horizontal planes in the model. The maximum shear stresses calculated by the finite element method were compared to those obtained by the photoelastic method, and they were found to compare favorably.