Patient was referred to Endo for apicoectomy #11. Now 6 months after treatment was provided, the patient has developed permanent paresthesia of the upper left lip near the surgical site. Could this be due to facial nerve damage or due to infraorbital nerve damage? Also, can this be related to flap technique above mucogingival junction to get access to the apex of the root? Is there a special precautionary protocol one must follow to avoid this type of nerve injury? Your help as well as input in this matter is greatly appreciated.