Stomatitis is an inflammation of the mucous lining of any of the structures in the mouth, which may involve the cheeks, gums, tongue, lips, throat, an roof or floor of the mouth. The inflammation can be caused by conditions in the mouth itself, such as poor oral hygiene, poorly fitted dentures, or from mouth burns from hot food or drinks, or by conditions that affect the entire body, such as medications, allergic reactions, radiation therapy, or infections. A form of stomatitis known as stomatitis nicotina can be caused by smoking cigars, cigarettes, and pipes, and is characterized by small red bumps on the roof of the mouth.