Aim: to retrospectively investigate the success rate of pulpectomy treatments of primary molars (with the use of calcium-hydroxide/iodoform paste) over 4 years together with the possible influence of different factors on the outcome. In addition, the possible influence of the treatment setting (general anesthesia, nitrous oxide sedation and local anesthesia) on the outcome was also analyzed. Materials and methods: patients’ digital records who underwent a pulpectomy treatment were retrospectively analyzed. The impact of various patient-related, tooth-related and treatment-related factors were analyzed. The influence of the treatment setting (treatments performed under general anesthesia, nitrous oxide sedation or local anesthesia alone) on the success of the pulpectomy treatment was additionally analyzed as it can affect patient’s compliance and thus the outcome. Multivariate and bivariate analyses were performed. Results: pulpectomy treatments performed under general anesthesia had the highest success rate (78.6%) 4 years posttreatment. Followed by nitrous oxide sedation (57.1%) and then local anesthesia alone (43.8%). Furthermore, the arch type was also found to be clinically and statistically significant. The failure rate of the pulpectomized primary molars in the upper arch was more than that in the lower arch four years posttreatment (61.5% vs 29.2%). Conclusion: preserving primary molars for as long as possible through pulpectomy treatment should always be included in the treatment planning of young children as it offers high success rates many years following the treatment, especially true for lower primary molars and cases performed under general anesthesia.