Relative shear bond strengths of luting media with various core materials

Abstract

T he coronal cast metal restoration continues to be commonly used to restore teeth severely damaged by caries or trauma and to strengthen endodontically treated teeth. Often, however, so little tooth structure remains that a casting could not be adequately supported and retained (either coronally or within the root canal) without an intermediate buildup with a suitable dowel or core. Important factors related to the success of a cast restoration are (1) the ‘design and quality of the tooth or core, and (2) the accuracy of the casting.’ Other factors that contribute to longevity and success include (1) the type of core material to which the casting is cemented, (2) the luting medium and its biophysical characteristics, and (3) the degree of bond strength between the cement and the core material.‘-3 In most instances, the core consists of various combinations of dentin and amalgam alloy, composite resin, noble alloy, or base metal alloy. The bond strength of a luting agent to dentin is an important consideration in the success of the cast restoration. It is equally important that the bond strength of luting agents to various core materials be within the range of clinical acceptability. The bond strengths of various luting agents have been widely reported in the literature, usually presented in terms of tensile characteristics.“’ Fewer studies have dealt with the bond strengths to core materials and dentin in terms of shear strength characteristics.6,7 Both shear and tensile strengths are relevant for retention of a casting. The purpose of this laboratory investigation was to compare the shear bond strength of representative luting agents to materials commonly used as cores for cast restorations.