ABSTRACT Background: This research has been conducted to assess the effect of orthodontic treatment on endodontically treated tooth. Materials and Methods: Overall, fifty subjects had been recruited. The participants received root canal therapy within 3 months as well as had an appointment for fixed orthodontic therapy. All candidates underwent an intraoral investigation. Radiographic evaluation as well as therapy planning were completed. Fixed orthodontic therapy had been initiated. All of the participants had been recalled. Endodontically restored teeth had been evaluated. All outcomes were assessed via Statistical Package for the Social Sciences (SPSS) software. Results: In this study, there were 25 males and 25 females. Pulp stones were seen in 15 subjects. Apical periodontitis was seen in nine subjects. Apical root resorption was seen in seven subjects, and enamel decalcification was seen in four subjects. Overall, 35 out of 50 subjects showed negative effects of orthodontic treatment on endodontically treated teeth. Conclusion: Excessive orthodontic force may result in increased pulp and peri-apical inflammation.