Can initial failed external resorption treatment be successfully corrected?

Patient: 24 year-old male in excellent health

Chief Complaint: Biting Sensitivity

Dental History: The patient reported having had root canal treatment performed by his general dentist in 2011 (3 years prior to the initial consultation with the author). His current local dentist noted gingival bleeding at a recent appointment and noted a root radiolucency consistent with external root resorption (maxillary right canine, tooth #6)