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Module 2: Dental Caries Process

2.4 Protective Factors

child at water fountain


Saliva provides a washing mechanism that helps return oral pH to the safe range. Saliva contains calcium and phosphate, which help to prevent the dissolution of enamel. A number of specific inorganic ions are also present that inhibit bacterial growth, thereby inhibiting the activity of Mutans streptococci on the tooth surface.

Fluoride Exposure

Fluoride is a safe and effective mechanism for preventing caries. Fluoride has been the major factor in the widespread reduction of dental caries in the United States and other industrialized nations. It combats the caries process in three ways.17

  1. Strengthens sound enamel. Fluoride concentrated in plaque, saliva, and outer layers of the tooth inhibits the demineralization of sound enamel.
  2. Promotes tooth remineralization. Fluoride in plaque and in saliva is absorbed into demineralized tooth surfaces and attracts other minerals, including calcium and phosphorous, which results in the formation of new minerals in the tooth. Remineralized tooth structure is harder than the original tooth structure.
  3. Inhibits Mutans streptococci’s ability to produce acids. Fluoride disrupts Mutans streptococci’s ability to metabolize sugars, thereby reducing the production of acids that demineralize teeth.

Fluoride delivered systemically through fluoridation of community water supplies and dietary supplements (e.g., tablets, drops) is one way to receive fluoride. This approach incorporates fluoride into young children’s developing permanent teeth.

For many children, community water fluoridation is their primary source of fluoride. Over 90 percent of community water supplies in Maryland are fluoridated. One way to determine the fluoride concentration of a particular community’s water supply or a private well is to contact the local health department.

Fluoride delivered topically through toothbrushing, mouthrinsing, and professionally applied fluoride varnish strengthens teeth present in the mouth, making them more resistant to dental caries. Topical fluoride is most effective when delivered at very low doses many times a day. Common topical delivery systems include toothpaste or dentifrices, gels, varnishes, and mouth rinses.