Dental plaque is a sticky film that grows on the surfaces inside the oral cavity, primarily forming on all the surfaces of the teeth. Made up of microorganisms that include bacteria and fungi, dental plaque is one of the most significant causes of tooth decay and gum disease. While dental plaque is colorless when it first forms, as it hardens and turns to dental calculus, it can turn brown or yellow. Plaque can be removed with traditional oral hygiene tools like toothbrushes and dental floss or other interdental cleaners, but dental calculus can only be removed by a dental health professional. If left undisturbed, the accumulation of plaque and calculus interacts with food debris and emits acids that destroy the tissues of the teeth and gums.

Though plaque can be removed with effective hygiene measures, it forms quickly on the teeth, necessitating repeated cleaning. This is one of the main reasons that dentists recommend brushing the teeth at least twice a day, if not more frequently, and cleaning between the teeth once a day. Shortly after the teeth are cleaned, a layer of saliva called a dental pellicle forms on the surfaces of the teeth. As bacteria attach to this dental pellicle, they form colonies and, when not consistently cleaned away, mature in the oral cavity and lead to disease. Different types of bacteria are more common above the gumline, while other types appear more frequently below the gumline; each type thrives in the environment where it lives.

The majority of microorganisms that make up dental plaque biofilm are anaerobic bacteria that feed on fermenting sugars that cling to the teeth in the debris left behind from food and drinks. As they mature and ferment, they release acids in the oral cavity that cause inflammation in the gingival tissues. This inflammation is characterized by swelling and redness in the gums and bleeding due to brushing or flossing and is called gingivitis. In this earlier stage, gingivitis can be reversed with treatment, which involves removal of the bacterial plaque from the oral cavity. If the plaque remains on the teeth, however, and is not removed, the inflammation can spread to the supporting tissues of the periodontium and lead to periodontitis. Periodontitis is an infection that begins in the gums and gradually leads to destruction of the bone in the jaw and possibly loss of the teeth. While periodontitis can be treated, once it has damaged the periodontal tissues, it cannot be reversed. The primary goal of treatment, which involves rigorous oral hygiene both at home and clinically, along with surgical debridement and the use of antibiotics, is to maintain the function and placement of the teeth as effectively as possible and to prevent further infection.

Dental plaque can also lead to dental caries, which are commonly referred to as cavities. Dental Caries are caused by the proliferation of acids in the oral cavity, which demineralize the enamel on the teeth and gradually break down the dentin, which is the tissue below the enamel on the surfaces of the teeth. Oral hygiene is effective at preventing dental caries, though they are also affected by risk factors that include the patient’s diet, behaviors, and genetics, along with their exposure to fluoride. Dentists can assist patients in effective teeth-cleaning techniques with the use of plaque disclosing gels or tablets, which indicate the presence of plaque biofilm on the teeth after cleaning and also highlights areas of plaque buildup that may be more difficult to effectively clean. Professional cleanings, which remove dental calculus and can remove dental plaque from harder-to-reach areas, are also instrumental in the prevention and treatment of dental caries, as well as in the prevention of gum diseases.