• halitosis – chronic bad breath, generally caused by an oral or gastrointestinal disorder
• hematoma – blood swelling beneath the surface of the skin, gums, or other tissue
• hygienist – dental professional who is trained and certified to perform dental cleanings, scaling and root planing, and other functions, provides patient education, and may administer local anesthetic or nitrous oxide
• hyperplasia – abnormal increase in cell growth leading to enlargement of tissue