Mahidol Study 3: Postoperative Effect and Adverse Events of Regenerative Endodontic Procedures in Immature Permanent Teeth

Introduction Regenerative endodontic procedures (REPs) have demonstrated high success rates; however, adverse effects and complications remain inadequately characterized. This study investigated the incidence and associated factors of tooth discoloration, intracanal calcification, and treatment failure, including fatal tooth fracture, following REPs in immature permanent teeth. Methods A retrospective cohort study was conducted on 120 immature permanent teeth treated with REPs at Mahidol University between January 2006 and May 2023. Clinical and radiographic outcomes were evaluated at a median follow-up of 30.5 months (12–148 months). Tooth discoloration and intracanal calcification were assessed, and multivariable modified Poisson regression was used to identify associated factors. Results Among 61 teeth with available discoloration data, 37 (60.7%) exhibited postoperative discoloration, with mineral trioxide aggregate identified as a significant risk factor compared to Biodentine ( P = .001). Partial intracanal calcification was observed in 60 teeth (50.0%), while complete canal obliteration was not detected. EDTA use during the bleeding induction visit was significantly associated with calcification ( P = .031). Thirteen teeth (10.8%) were classified as disease, with causes comprising persistent infection (4 teeth), coronal and/or root fracture (3 teeth), coronal leakage (2 teeth), postoperative trauma (2 teeth), parafunctional force (1 tooth), and unidentified cause (1 tooth). Conclusions Tooth discoloration and partial intracanal calcification are common adverse effects following REPs. Mineral trioxide aggregate was significantly associated with discoloration, and EDTA irrigation during the bleeding induction visit was significantly associated with intracanal calcification. As a case-series observation, three fatal crown–root fractures occurred, in which coronal barrier positioning appeared to leave inadequate depth for bonded composite restoration; this descriptive observation is hypothesis-generating and warrants confirmation.