In modern dentistry, the optimal treatment of the crowns of root-treated teeth whose crown structure has suffered severe destruction has always been a challenge. The use of Post and Core casting is a way to reconstruct teeth after root canal treatment, whose long-term success has been proven in studies, and it is the treatment of choice for reconstructing teeth with high decay. Therefore, this study was conducted to investigate the fracture strength of root-treated teeth that have been restored with nickel-chromium posts and non-precious gold alloys (NPG). In this study, 20 maxillary central teeth were collected and root canal treatment was performed with the same conditions and equipment for each tooth. Then each tooth was mounted in clear acrylic blocks. Posts and Cores were made by direct method. Then the samples were randomly divided into two groups of 10 each. The posts were cemented and the samples were placed in simulated conditions in the oral environment, and then the Universal Testing Machine recorded the fracture strength of the samples. The t-test was used to compare the average fracture strength. Based on the results, the fracture strength of nickel-chromium post was higher than the fracture resistance of NPG, but there was no significant difference between the two groups (p > 0.05). In both groups, most types of failure were irreversible, and there was no difference in the type of failure between the two groups (p > 0.05). Based on the results of this study, the fracture strength of teeth restored with two types of post and Core casting, NPG and nickel chrome, is not different from each other.
