Patient-friendly definition from the DentistsDirectory.org dental glossary.
Gingivitis is inflammation of the gum tissue (gingiva) caused by bacterial plaque accumulating at and below the gum line. It is the earliest and mildest form of periodontal disease and — critically — the only stage that is fully reversible. The bacteria in plaque release toxins that trigger the body's immune response in the gum tissue, producing the classic signs of inflammation: redness, swelling, and bleeding.
The most reliable early sign of gingivitis is bleeding during brushing or flossing — even a small amount of blood on the toothbrush or floss indicates inflamed gum tissue. Healthy gums do not bleed with normal brushing. Other signs include gums that look darker red rather than a healthy coral pink, swollen gum margins that look puffy rather than knife-edged against the teeth, and gums that are tender to touch. Gingivitis itself is not typically painful, which is why many people are unaware they have it.
Because gingivitis has not yet caused destruction of the bone and ligaments supporting the teeth, it is entirely reversible. A professional cleaning to remove the plaque and tartar that brushing cannot reach, combined with diligent daily brushing and flossing at home, typically resolves gingivitis within one to two weeks. The key word is consistency — gingivitis recurs quickly if oral hygiene lapses. Left untreated over time, gingivitis can progress to periodontitis, the irreversible stage of gum disease that destroys the bone supporting the teeth.