Survival rate and fracture strength of endodontically treated maxillary incisors with moderate defects restored with different post-and-core systems:An in vitro study

Purpose: This study compares the survival rate and fracture strength of end odontically treated maxillary incisors with moderate coronal defects restor ed with different post-and-core systems after exposure to an artificial mou th. Materials and Methods: Sixty-four caries-free human maxillary central i ncisors were selected for standardized size and quality, endodontically tre ated, and decoronated 2 mm coronal to the cementoenamel junction. Group 1 w as restored with titanium posts and composite cores, group 2 received zirco nia posts and a composite core, and in group 3 zirconia posts with a heat-p ressed ceramic core were used. Teeth restored with cast posts and cores ser ved as controls. All teeth were prepared and restored with complete cast cr owns. All samples were exposed to 1.2 million cycles in a computer-controll ed chewing simulator with simultaneous thermocycling. In addition, the samp les were loaded until fracture in a static testing device. Results: The sur vival rates of the different groups were. 94%, for titanium/composite, 63% for zirconia/composite, 100% for the all-ceramic post and core, and 94$%, f or the cast post and core. The following mean fracture strengths were obtai ned: titanium/composite = 425 +/- 155 N, zirconia/composite = 202 +/- 212 N , zirconia/ceramic = 378 +/- 64 N, cast post and core = 426 +/- 178 N. The lower fracture load in the group with zirconia posts and composite core was statistically significant. The use of zirconia posts resulted in fewer obl ique root fractures. Conclusion: Prefabricated titanium posts with composit e cores, zirconia posts with heat-pressed ceramic cores, and cast posts and cores yield comparable survival rates and fracture strengths for the resto ration of crowned maxillary incisors with moderate coronal defects. Surviva l rates and fracture strengths for zirconia posts with composite cores are significantly lower, so this combination cannot be recommended for clinical use.