FRACTURE-TOUGHNESS DETERMINATION OF DENTAL MATERIALS BY LABORATORY TESTING AND FINITE-ELEMENT MODELS

This study assessed the effectiveness of finite element analysis in pr edicting the stress intensity factor (K-IC) for three types of dental materials: a glass ionomer, a dental amalgam, and a composite resin. L aboratory tests were conducted on small single-edge notch specimens lo aded in three-point bending to determine values for fracture toughness (K-Q). Using the dimensions measured for each laboratory specimen, a J integral approach was employed to calculate K-IC using finite elemen t analysis. Both two-dimensional, plane strain and three-dimensional m odels were used in determining K-IC for each specimen, and these value s were compared to the K-Q values obtained from laboratory tests. The results indicated that no significant differences existed between labo ratory results and those obtained from both two- and three-dimensional finite element models (P > .85). For the three-dimensional model valu es for K-IC were found to vary across the specimen thickness, with the values at the center of the specimen closely paralleling those obtain ed from the two-dimensional plane strain model. It was concluded that the two-dimensional plane strain J integral technique was as effective as the three-dimensional technique in calculating values for K-IC. (C ) 1995 John Wiley & Sons, Inc.