Summary: Gingivitis is inflammation of the gums.Gingivitis is a form of periodontal disease. Periodontal disease is inflammation and infection that destroys the tissues that support the teeth. This can include the gums, the periodontal ligaments, and the tooth sockets.Gingivitis is due to the long-term effects of plaque deposits on your teeth. Plaque is a sticky material made of bacteria, mucus, and food debris that builds up on the exposed parts of the teeth. It is also a major cause of tooth decay. If you do not remove plaque, it turns into a hard deposit called tartar (or calculus) that becomes trapped at the base of the tooth. Plaque and tartar irritate and inflame the gums. Bacteria and the toxins they produce cause the gums to become infected, swollen, and tender. More >> Less >>

Reference Material:
https://medlineplus.gov/ency/article/001056.htm