Dental infections are infections that originate at the tooth or its supporting structures and can spread to the surrounding tissue. Dental infections generally occur when bacteria invade the pulp and spread to surrounding tissues. Dental infections most commonly occur when bacteria invade the pulp and spread to surrounding tissues; this can occur due to trauma, dental caries, and dental procedures. Periodontal infections affect the gums, causing gingivitis and over time, periodontitis. Periodontal infections particularly result from poor or ineffective dental hygiene leading to plaque formation and subsequent inflammation of tissues around the teeth. A bacterial infection can lead to sores and swelling in the mouth. Infections may be caused by an overgrowth of organisms normally present in the mouth or by newly introduced organisms, such as the bacteria that cause syphilis or gonorrhea.