Dental plaque is mainly harmful to teeth and gums, which is the two most common diseases of the oral cavity: caries and periodontal disease.
Caries are commonly known as "worms", where "worms" refer to bacteria in plaque. Dental plaque is firmly attached to the tooth surface. The bacteria ingest the sugar in the saliva and break down the sugar to produce acid. These acids will damage the tooth and eventually create a cavity.
When dental plaque is close to the gums, the toxins and other harmful substances produced by the bacteria can irritate the gums (commonly known as "gums" and "gums"), causing inflammation, that is, gingivitis. If it is not controlled and allowed to develop, gingivitis may develop into irreversible periodontitis, causing damage to the alveolar bone, and eventually leading to tooth loosening and loss.