Factors Influencing the Long-Term Survival and Success of Endodontically Treated and Retreated Teeth: An Ambispective Study at an Educational Hospital

Background: This ambispective study evaluated the prognostic factors for long-term survival and success of endodontically treated teeth (ETT) in patients treated at an educational hospital. Methods: Patients who received root canal treatment (RCT) at Princess Nourah bint Abdulrahman University (2018–2023) were included if the following criteria were met: follow-up time of a minimum of 12 months was available, and clear pre- and post-treatment periapical radiographs. Two calibrated examiners assessed RCT quality along with pre-treatment and follow-up periapical index (PAI) scores. Coronal restorations were evaluated for quality, type, and timing. Data on oral hygiene, smoking, systemic health, periodontal status, and occlusal factors were collected. Tooth survival was defined as a functional, asymptomatic tooth, while success required a clinically asymptomatic tooth with a PAI score ≤ 2. Multivariate regression analysis was performed to assess the influence of the collected variables on tooth survival and success. Statistical significance was set at p < 0.05. Results: A total of 461 ETT from 242 patients were analyzed. The survival rate was 89%, while 81% met the treatment success criteria. Most patients were female (65%), and only 8.9% had a healthy periodontium. Multivariate analysis identified preoperative PAI score, obturation density, and coronal restoration quality as significant predictors of survival and success (Nagelkerke R2 = 0.338). Conclusions: ETT demonstrated high survival and success rates. Preoperative PAI score, obturation density, and coronal restoration quality were key predictors of long-term treatment outcomes, highlighting the importance of comprehensive pre-treatment assessment and high-quality endodontic and restorative procedures.