Overall, is in response to bacterial biofilms (also called plaque) that is attached to tooth surfaces, termed plaque-induced gingivitis. Most forms of gingivitis are plaque-induced.

While some cases of gingivitis never progress to periodontitis, periodontitis is always preceded by gingivitis.

Gingivitis is reversible with good oral hygiene; however, without treatment, gingivitis can progress to periodontitis, in which the inflammation of the gums results in tissue destruction and bone resorption around the teeth. Periodontitis can ultimately lead to tooth loss.