Is Etiology a Key Factor for Regenerative Endodontic Treatment Outcomes?

This study aimed to evaluate treatment outcomes of regenerative endodontic treatment (RET) in nonvital immature permanent teeth due to developmental malformation and trauma, and to analyze the influence of etiology on the prognosis. Fifty-five cases were included and divided into a malformation group (n = 33) and a trauma group (n = 22). Treatment outcomes were classified as healed, healing, and failure. Root development was evaluated in terms of root morphology and the percentage changes in root length, root width, and apical diameter during a follow-up period of 12–85 months (mean 30.8 months). The mean age and the mean degree of root development in the trauma group were significantly younger than that in the malformation group. The success rate of RET was 93.9% (81.8% healed, 12.1% healing) in the malformation group and 90.9% (68.2% healed, 22.7% healing) in the trauma group, showing no statistically significant difference. The proportion of type I–III root morphology in the malformation group (97%, 32/33) was significantly higher than that in the trauma group (77.3%, 17/22) (P