How does plaque buildup cause gingivitis?

Gingivitis is the inflammation of the gums, and its most common cause is the accumulation of dental plaque on exposed tooth surfaces.1

When bacterial plaque is deposited on the teeth—particularly below the gum line—it acts as an irritant to the surrounding tissues. This persistent presence of plaque causes the neighboring soft tissues to become inflamed, leading to symptoms such as tenderness, swelling, and bleeding. While this initial stage of inflammation is reversible through proper dental hygiene and the removal of plaque deposits, failing to address the buildup can allow the condition to progress to more severe forms of periodontitis, which may eventually result in the loss of teeth.21