objective: restoration of non-vital teeth is always a challenge for dentists. Therefore, we decided to compare fracture resistance of endodontically treated maxillary premolars restored with Amalgam and Composit direct restorations and ceramic Inlay indirect restorations Methods: 50 intact maxillary premolarswere divided to 5 groups (n=10). Teeth of first group were remined intact as negative control. The other teeth got root canal therapy and then MOD cavity preparation connected to access cavity. In this level, one other group of teeth were considered as positive control. The teeth of groups 3, 4, 5 restored respectively with Amalgam Composite and Zirconium ceramic Inlays. The fracture resistances of all samples were tested by Universal testing machine. The data were obtained in SPSS software version 25and one way ANOVA with supplementary Tukey test was used. Results: The difference between the negative control and ceramic groups, as well as between the ceramic and composite groups, was not significant. But the fracture resistance of all three mentioned groups was significantly higher than amalgam. Also, the amalgam fracture resistance was significantly higher than the positive control group. Conclusion: it seems that the indirect restoration of zirconia ceramic inlay has more fracture resistance than the direct restorations of Composite and Amalgam.

fracture resistance, Endodontically treated maxillary premolar, Amalgam restoration, Composite restoration, Ceramic Inlay