Post retention and post/core sheer bond strength of four post systems

As clinicians we continue to search for a post system which will give us ma ximum retention while maximizing resistance to root fracture. The introduct ion of several new post systems, with claims of high retentive and resistan ce to root fracture values, require that independent studies be performed t o evaluate these claims. This study tested the tensile and shear dislodgmen t forces of four post designs that were luted into roots 10 mm apical of th e CEJ. The Para Post Plus (P1) is a parallel-sided, passive design; the Par a Post XT (P2) is a combination active/passive design; the Flexi-Post (F1) and the Flexi-Flange (F2) are active post designs. All systems tested were stainless steel. This study compared the test results of the four post desi gns for tensile and shear dislodgment, All mounted samples were loaded in t ension until failure occurred. The tensile load was applied parallel to the long axis of the root, while the shear load was applied at 450 to the long axis of the root, The Flexi-Post (F1) was significantly different from the other three in the tensile test, however, the Para Post XT (P2) was signif icantly different to the other three in the shear test and had a better pro bability for survival in the Kaplan-Meier survival function test. Based on the results of this study, our recommendation is for the Para Post XT (P2).