Retreatment of Failed Regenerative Endodontic Therapy: Outcome and Treatment Considerations.

Introduction Regenerative endodontic therapy (RET) has been suggested for treating immature necrotic teeth, and failures after RET may be observed during follow-up examinations, even two years after the initial treatment. The study aimed to examine the outcomes of RET and suggest a decision-making guide for the retreatment of failed cases. Methods Around 414 endodontically treated immature teeth from patients aged six and 17 were screened to identify eight patients who presented with a failed RET. Data, including patients' ages, sex, medical, and dental history, were collected. Results The timing of failure varied significantly. Only one tooth showed failure at the three-month initial follow-up, while the remaining five teeth exhibited failures between two and seven years post-RET completion. Notably, in most instances, failure occurred after the periapical lesion had healed and root development had continued. Six teeth underwent retreatment using various approaches: repeated RET (two teeth), conventional root canal retreatment with or without an apical plug (two teeth), and surgical retreatment (two teeth). All retreatment interventions resulted in favorable outcomes. Conclusion Despite initial RET failure, the subsequent process of maturogenesis that followed the primary treatment led to an improved crown-to-root ratio. This resulted in a better outcome for the secondary treatment and increased patient cooperation during subsequent treatments. The study presents guidelines to aid in treatment decision-making for similar cases.