IMPORTANCE OF VITALITY TESTING: This 36-yo healthy, Caucasian female was referred for endodontic treatment of asymptomatic tooth #23. Radiolucency tooth #23 was noted by her dentist upon evaluation for Invisalign®. See chart for clinical findings. Pt denied history of trauma. Due to positive response to vitality testing, expansion of L cortical plate, tooth mobility, and mixed radiopaque-radiolucent radiographic appearance, the lesion was determined to be of non-endodontic origin. The patient was referred to an oral surgeon for further evaluation and treatment. We recently followed-up with the patient’s oral surgeon. The lesion was biopsied and determined to be fibro-osseous dysplasia.