ABSTRACT
Statement of the Problem: The survival of pulpless teeth restored with different post and core systems is still a controversial issue
Purpose: This study compared the retention of two different post and core systems and also the fracture resistance of teeth restored with these systems
Material and Method: Eighty endodontically treated maxillary central incisors were sectioned perpendicular to the long axis at a point 2mm incisal to the cementoenamel junction [CEJ] and then the root canals were obturated. The restored teeth were randomly divided into two equal groups of 40. One group was restored with Nickel-Chromium [Ni-Cr] post and core system and the other group with Non-Precious Gold alloy [NPG] system. For evaluation of fracture resistance of the restored teeth, the specimens [n=20 per each group] were mounted in acrylic resin blocks and a layer of polyvinyl siloxane was applied to cover the roots. Loads were applied at an angle of 45 degrees to the long axis of the teeth and measured with a universal testing machine. The axial retention values of the studied groups [no=20] were measured on an Instron testing machine at a crosshead speed of 0.5 mm/min. Statistical analyses were performed using SPSS version 19.00 and student's t-test [alpha=0.05]
Results: Although retention failure load for Ni-Cr system was lower than NPG system, there was no significant difference between the two systems [p= 0.7]. However, fracture resistance of the teeth restored with Ni-Cr post and core system was significantly higher than NPG group [p= 0.000]
Conclusion: There was no significant difference between the retention of the studied post and core systems. Although significantly higher fracture thresholds were recorded for Ni-Cr post and core group, the failure loads of both systems may rarely occur clinically