The resistance to tensile, compression, and torsional forces provided by four post systems

This study measured the force required to displace four different endodontic posts (an experimental, Para-Post, Flexi-Post, and V Lock) when tensile, torsion, or compressive forces were applied. Extracted mandibular premolars were decoronated at the cementoenamel junction, the roots were divided into groups of similar size, and the pulpal tissue was removed. The canals were enlarged, cleaned, and filled with gutta percha. Post preparations were made, and the posts were cut and cemented into the post spaces with resin cement. The roots were notched with a separating disc and lowered into a metal tube filled with acrylic resin. Two Minim pins were placed into the coronal dentin paralleling the post. Composite resin cores were made around the coronal 4 mm of the posts and the two pins for 10 specimens from each group. The specimens were placed into a standardized fixture and a load applied until failure. The tensile load required to pull the experimental post and resin was significantly less than the load required to remove the threaded posts. Flexi-Posts provided the greatest resistance to torsion and tensile loading. The compressive load required to fracture the core over the V-Lock post was significantly greater than the other post systems.