Aim: The aim of this retrospective study is to review the tooth retention rate of primary endodontically treated teeth at University of Pennsylvania Graduate Endodontics department (PGE) and faculty practice (PDFP) and compare it to the tooth retention rate of non-surgical retreatment and surgical retreatment and test the hypothesis-- the survival rate of secondary RCT is lower than the rate of initial RCT. Also, this study analyzed systemic and local co-factors affecting longevity of these endodontically treated teeth. Systemic factors included smoking, diabetes, and drug allergy. Local factors included tooth position, presence of core buildup, post and core, and full coverage crown. These patients were reviewed to observe if they had periodontal conditions and if other periodontal treatments were provided. Material and methods: Electronic health records of patients who had primary endodontic treatment at PDM Graduate Endodontic clinic and PDFP of the University of Pennsylvania from January 1, 2017 to December 31, 2020 were analyzed and followed until June, 10, 2021 Results: 9107 patients (11854 teeth) had RCT done at PDM from 2017 to 2020. Of these patients, 990 patients (1627 teeth) were excluded because they had initial RCT somewhere else other than at PGE or PDFP. 8117 patients (10227 teeth) were reviewed for extractions and secondary treatments. Of 10227 teeth, 393 teeth were extracted. Of 393 teeth, 384 teeth were extracted without any type of retreatments. 9 teeth were extracted after retreatment. Of these 9 teeth, 7 teeth had nonsurgical retreatment and 2 teeth had surgical retreatment. Chi square and logistic regression analyses showed that there is no statistical significance between extraction rate of primary RCT teeth and extraction rate of NS retx teeth. Also, these analyses demonstrated that there is no statistically significant difference between extraction rate of primary RCT teeth and that of surgical retx teeth. Most extractions and NS retx occurred after 12+ months unlike surgical retx which happened more commonly in the first 0-6 months. Systemic factors such as diabetes, smoking, and drug allergy were reviewed. 342 patients underwent extractions. Chi square analysis showed statistical difference for smokers, diabetic patients, and drug allergy patients in relation to tooth loss. Logistic regression and Kaplan Meier analysis showed only drug allergy and tooth loss are correlated. Of drug allergy patients, 38.8% were allergic to penicillin. Local factors such as tooth position, restorations, periodontal conditions were reviewed. Based on chi square, patients with buildup, full coverage crown, PD≤ 5mm before and after RCT showed statistically significant difference. However, tooth position, post and core, CLP, and SRP did not show statistically significant difference. Based on logistic regression, results were similar except for SRP which demonstrated statistical significance. Based on Kaplan Meier analysis, core buildup, full coverage crowns, presence of PD≥5mm after RCT, and SRP made a statistical difference. However, tooth position, post and core, PD≥ before RCT, CLP did not make a statistical significance. Conclusion: This study concluded that endodontic treatment is a viable option if RCT gets performed properly using the proper techniques, material, and technologies. Patient’s health history (eg. diabetes, smoking, and drug allergy) and dental history (eg. build up, crowns, periodontal treatments) can result in difference in the outcome of the endodontic therapy regardless of the treatment modalities.