Fracture resistance of different post-and-core repair systems after warm gutta filling

Qi Lu; Wang Xing; Ma Jun-yue; Wu Pei-ling

doi:10.3969/j.issn.2095-4344.2015.38.018

Abstract：BACKGROUND:Due to the complexity and irregularity of bypass obturation of oval root canal and the particular stress of the post and core to the tooth, we have not yet found a reasonable post crown for dental restoration after bypass obturation of the oval root canal. <br> OBJECTIVE:To compare the flexural capacity of the three kinds of post-and-core repair systems (cobalt-chromium cast post and core, zirconium oxide post and core, and CAD/CAM-fabricated glass fiber post and core) after bypass obturation of the oval root canal warm gutta. <br> METHODS: Ninety mandibular first premolars were selected for bypass obturation of the root canal with Obtura II & System B, and then randomized into three groups that were respectively restored with cobalt-chromium cast post and core, zirconium oxide post and core and CAD/CAM-fabricated glass fiber post and core. After that, cobalt-chromium metal crown was used for ful-crown restoration. Fracture strength and fracture type were recorded in different groups. <br> RESULTS AND CONCLUSION: The fracture resistance was higher in the cobalt-chromium cast post and core group and zirconium oxide post and core group than the glass fiber post and core group (P < 0.05), and the former two groups had no significant difference. Cobalt-chromium cast post and core was fractured at the root of tooth, and could not be repaired; the zirconium oxide post and core was fractured at the root neck and root of tooth, which was confirmed as reparative fracture; the glass fiber post and core was fractured at the tooth neck, which could be restored. These findings indicate that the cobalt-chromium cast post and core can bear greater occlusal force, but has a higher probability of root fracture; the CAD/CAM-fabricated glass fiber post and core exhibits a lower probability of root fracture