page_title: Tooth decay
section_title: Exposure
hierarchical_section_title: Tooth decay / Cause / Exposure
caption_attribution_description: English: Stephan curve, showing sudden decrease in plaque pH following glucose rinse, which returns to normal after 30-60 mins
context_page_description: Tooth decay, also known as dental caries or cavities, is a breakdown of teeth due to acids made by bacteria. The cavities may be a number of different colors from yellow to black. Symptoms may include pain and difficulty with eating. Complications may include inflammation of the tissue around the tooth, tooth loss, and infection or abscess formation.
  The cause of cavities is acid from bacteria dissolving the hard tissues of the teeth. The acid is produced by the bacteria when they break down food debris or sugar on the tooth surface. Simple sugars in food are these bacteria's primary energy source and thus a diet high in simple sugar is a risk factor. If mineral breakdown is greater than build up from sources such as saliva, caries results. Risk factors include conditions that result in less saliva such as: diabetes mellitus, Sjögren syndrome and some medications. Medications that decrease saliva production include antihistamines and antidepressants. Dental caries are also associated with poverty, poor cleaning of the mouth, and receding gums resulting in exposure of the roots of the teeth.
context_section_description: The frequency with which teeth are exposed to cariogenic (acidic) environments affects the likelihood of caries development.  After meals or snacks, the bacteria in the mouth metabolize sugar, resulting in an acidic by-product that decreases pH.  As time progresses, the pH returns to normal due to the buffering capacity of saliva and the dissolved mineral content of tooth surfaces.  During every exposure to the acidic environment, portions of the inorganic mineral content at the surface of teeth dissolve and can remain dissolved for two hours.  Since teeth are vulnerable during these acidic periods, the development of dental caries relies heavily on the frequency of acid exposure.
  The carious process can begin within days of a tooth's erupting into the mouth if the diet is sufficiently rich in suitable carbohydrates. Evidence suggests that the introduction of fluoride treatments has slowed the process.  Proximal caries take an average of four years to pass through enamel in permanent teeth.  Because the cementum enveloping the root surface is not nearly as durable as the enamel encasing the crown, root caries tend to progress much more rapidly than decay on other surfaces.  The progression and loss of mineralization on the root surface is 2.5 times faster than caries in enamel.  In very severe cases where oral hygiene is very poor and where the diet is very rich in fermentable carbohydrates, caries may cause cavities within months of tooth eruption. This can occur, for example, when children continuously drink sugary drinks from baby bottles (see later discussion).
caption: "Stephan curve", showing sudden decrease in plaque pH following glucose rinse, which returns to normal after 30–60 min. Net demineralization of dental hard tissues occurs below the critical pH (5.5), shown in yellow.
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