Inflammation of the gums. Gingivitis is a reversible stage of gum disease and is usually the result of a build-up of plaque around the base of the teeth. Toxins produced by bacteria in the plaque irritate the gums, causing them to become infected, swollen, tender, and red-purple in colour. Gingivitis can also result from injury to the gums, usually through rough toothbrushing or flossing. Pregnant women and people with diabetes mellitus are especially susceptible. Good oral hygiene is the main means of preventing and treating gingivitis. Untreated, it may damage gum tissue, which may lead to chronic periodontitis. Acute ulcerative gingivitis may develop in people with chronic gingivitis, especially those with lowered resistance to infection (see gingivitis, acute ulcerative).