THE RETENTION OF CORE COMPOSITES, GLASS IONOMERS, AND CERMETS BY A SELF-THREADING DENTIN PIN - THE INFLUENCE OF FRACTURE-TOUGHNESS UPON FAILURE

"Core composite" is available, and glass ionomer or materials based upon it (i.e., cermet, alloy/glass-ionomer mix) have potential for core-forming. Cores are retained routinely by pins, and the suitability of the retention of these materials by pins has been investigated. The maximum tensile force sustained by a particular self-threading dentin pin, selected for its retentive capability, was determined. Pins were embedded to a constant depth in cylindrical specimens. All specimens fractured at a force which correlated linearly with the fracture toughness of the embedding material. The glass-ionomer group of materials was inferior to the core composites, and doubts must surround the use of the former when retention of a core is dependent on dentin pins. The adhesive character of the glass-ionomer-based materials did not lead to failure forces higher than those predicted from their fracture toughnesses. When the data points for these materials were placed on a fracture force/fracture toughness plot together with data from earlier research, no point was displaced significantly from the straight line. © 1990.