Halitosis (Fetor Oris; Bad Breath; Oral Malodor) By Bernard J Hennessy, DDS, Texas A&M University, College of Dentistry Reviewed / Revised Feb 2022 | Modified Sep 2022 View Patient Education Pathophysiology Etiology Evaluation Treatment Geriatrics Essentials Key Points Topic Resources Some Causes of Halitosis Halitosis is a frequent or persistent unpleasant breath odor.