INTRODUCTION: This retrospective study aimed to investigate the clinical outcomes and prognostic factors of regenerative endodontic procedure (REP) in terms of the resolution of apical periodontitis (AP), root development (RtDev), and intracanal calcification (IC). METHODS: The clinical outcomes of total 111 cases from 94 patients who underwent REPs between 2015 and 2020 were assessed based on clinical and radiographic evaluations. RESULTS: The cumulative survival rate was 85.15%, and Rt Dev was identified in 67.33% of cases. The incidence of IC has increased over time, reaching 43.45%. Median follow-up time was 1,267 days (95% CI: 991-∞) for AP healing and RtDev, and 776 days (95% CI: 563-1,754) for IC. The 4 CONCLUSIONS: The stage of root development and duration of intracanal medication significantly affected AP healing and RtDev. Additionally, age and the presence of a periapical lesion were found to influence RtDev, whereas etiology was identified as the only predictor of IC.