A comparison of the fracture resistance of core materials using different types of posts.

OBJECTIVE

The purpose of this in vitro study was to determine the fracture resistance of 3 core materials (silver amalgam, resin composite, glass-ionomer cement) supported by 1 custom cast post (nickel-chromium alloy) and 2 prefabricated posts (Radix and Safix posts).

METHOD AND MATERIALS

A sum of 45 recently extracted single-rooted human incisors and canines were placed in 0.5% sodium hypochlorite. Before the experiments, the anatomic crowns of teeth were removed below the cementoenamel junction to obtain a standard root length. The roots were endodontically treated by the manual condensation method. The teeth were randomly divided into 9 groups with 5 samples per group. The posts were luted in the corresponding root canals with zinc polycarboxylate cement. Each core reconstruction was prepared with diamond instruments, and the height of cores formed was 6.0 mm. The tooth and post-core combinations were mounted in acrylic resin blocks. Each tooth and post-core combination was placed in a special jig at a 45-degree angle to the buccal/lingual axis and then subjected to a load on an electronic pull-tension-compression testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed using one-way analysis of variance.

RESULTS

The resistance to fracture for prefabricated posts was significantly higher for resin composite core than for the other post-core combinations (P <.001). For prefabricated posts, the composite core and amalgam core materials were significantly stronger than the glass-ionomer core material (P <.001). The differences between the core materials were statistically significant (P <.001).

CONCLUSION

The glass-ionomer core with custom post was the weakest post-core system, while the prefabricated posts (Safix and Radix) with resin composite and amalgam cores were the strongest post-core systems.