Often in the clinical routine we come across cases where the planned goal is not achieved, and often knowing where and when to stop is the key to treatment success. In this case, the colleague sent the patient for attempted endodontic treatment after access and exploration of the canals, without success. There was a CT scan that showed no radiographically visible canals and periapical images incompatible with normality. In the clinical examination there were no signs or symptoms. There was then an attempt to locate the canals with microscopy and success only in DV. The patient was then oriented for clinical and radiographic follow-up. In case of failure, alternative treatments should be planned, such as surgical or guide access.