Analysis of fracture resistance of endodontically treated teeth restored with different post and core system of variable diameters: an in vitro study.

The restoration of endodontically treated teeth requires the fabrication of a post and core; to provide retention and support for the final crowns. The purpose of this study was to evaluate fracture resistance of endodontically treated teeth restored with prefabricated zirconia post (CP), milled zirconia post (MZ), pressable ceramic post (PC) and cast metal post (Ni-Cr) of 1.4 and 1.7 mm diameter. 48 freshly extracted human maxillary central incisors were used for this study. The teeth were distributed in four groups of 12 teeth each. From each group, 6 teeth were selected for 1.4 mm diameter post and rest of the 6 teeth, is selected for 1.7 mm diameter post. All teeth were restored with metal crowns. Each specimen from the group was subjected to "load to fracture" in universal testing machine at 130° angle and the maximum load at failure was recorded. Statistically significant difference was found between the failure load of the groups studied. In group I (Ni-Cr)-1.4 mm diameter post and core recorded a maximum fracture load of 534.83 ± 1.28 N and 1.7 mm diameter post and core showed 294.33 ± 1.02 N. In group II (PC)-1.4 mm diameter post and core recorded a maximum fracture load of 205.33 ± 1.61 N and 1.7 mm post and core showed 375.00 ± 1.57 N. In group III (CP)-1.4 mm diameter post and cores recorded a maximum fracture load of 313.00 ± 0.73 N and 1.7 mm post and core showed 638.67 ± 0.81 N. In group IV (MZ)-1.4 mm diameter post and cores recorded a maximum fracture load of 312.00 ± 0.86 N and 1.7 mm post and core showed 415.00 ± 0.89 N. Prefabricated zirconia post (1.7 mm) with pressable ceramic core (Cosmo post)-exhibited higher fracture resistance. Milled zirconia and prefabricated zirconia post-showed same value with 1.4 mm diameter post. Pressable ceramic post and core showed satisfactory result with 1.7 mm post, but showed lesser values with 1.4 mm diameter post.