In vitro shear strength of bonded amalgam cores with and without pins

This study compared the shear bond strength of resin-bonded amalgam with and without pins. The coronal third of 240 embedded posterior teeth was removed to expose a flat, nonretentive surface. Three Minikin pins were placed in the dentin in a triangular pattern 1 mm apart. Amalgam was condensed into a Delrin mold (4.2 mm in diameter and 3 mm in height) positioned over each tooth. The adhesives Amalgam-bond, All-bond, Amalgambond with high-performance additive, Panavia EX, and Panavia with Photobond were the materials used to bond the amalgam to the dentin. Half of the samples were immersed in normal saline solution for 7 days and the others for 30 days. Shear bond strengths were recorded as the maximum load per cross-sectional area of the bonded surface with a testing machine with 1 kN load cell and crosshead speed of 0.5 mm/min. A three-factor analysis of variance and Student-Newman-Keuls test (p = 0.05) identified Amalgambond with high-performance additive as the strongest adhesive in this study. The use of pins with or without adhesives increased the shear strength of amalgam samples significantly more than samples that used adhesives alone.