Objective: To detect the outcome of the application of mineral trioxide aggregate (MTA) on teeth with poor prognosis. Methods: MTA was clinically applied in surgical or nonsurgical approach to fill the root-end cavity, repair the root perforation, form apical plug, and limit the external resorption defect with the aid of a surgical operating microscope. Healing was evaluated clinically and radiographically. Results: In each case, MTA allowed bone healing and elimination of clinical symptoms. Conclusion: MTA can be successfully utilized in handling the challenge of preserving teeth with poor prognosis.