Compressive Shear Strength of Core Materials and Restoring Techniques

In this study, ninety extracted endodontically treated mandibular molars were mounted in acrylic resin blocks. Five groups of eighteen extracted teeth were prepared by two different techniques. A peripheral shelf 2 mm deep and 1.4 mm wide was prepared as a first technique, while TMS pins were used in the second group. The teeth were then restored with five different core materials: silver-reinforced glass-ionomer, resin-modified glass-ionomer, self-cured glass-ionomer, polyacid-modified composite resin, and titanium-reinforced composite resin. An Instron testing machine was used to apply shear force at a crosshead speed of 2 mm/min until fracture occurred. The results were obtained statistically using analysis of variance and least significant difference tests. According to the results of this study, Ti-core and composite resin were the strongest core materials when subjected to shear forces, and the most retentive preparation design was the vertical-pin design. The fractures of these materials with a vertical-pin design were mostly seen at the core and the tooth.