Flexural properties of endodontic posts and human root dentin

ObjectivesTo evaluate the flexural modulus and flexural strength of different types of endodontic post in comparison with human root dentin.MethodsThree different types of fiber-reinforced composite (FRC) posts and three metal posts each comprising 10 specimens (n = 10) and 20 dentin bars were loaded to failure in a three-point bending test to determine the flexural modulus (GPa) and the flexural strength (MPa). Three randomly selected fiber posts of each group were evaluated using a scanning electron microscope (SEM) to illustrate the differences in mode of fracture. Data were subjected to a one-way ANOVA to determine significant differences between groups and the Bonferroni t-test multiple comparison was applied to investigate which mean values differed from one another with significance levels of P < 0.05.ResultsThe flexural modulus recorded for the dentin bars was 17.5 ± 3.8 GPa. The values for posts ranged from 24.4 ± 3.8 GPa for silica fiber posts to 108.6 ± 10.7 GPa for stainless steel posts. The flexural strength for dentin was 212.9 ± 41.9 MPa, while the posts ranged from 879.1 ± 66.2 MPa for silica fiber posts to 1545.3 ± 135.9 MPa for cast gold posts. The ANOVA test analysis revealed significant differences between groups (P < 0.05) for flexural modulus and flexural strength mean values.SignificanceFRC posts have an elastic modulus that more closely approaches that of dentin while that for metal posts was much higher. The flexural strength of fiber and metal posts was respectively four and seven times higher than root dentin.