Because gum chewing is pleasurable, people normally chew for longer periods of time than they spend brushing their teeth. Likewise, gum may complement toothbrushing by reaching many of the tooth surfaces commonly missed during brushing. The average American fails to contact approximately 40% of tooth surfaces during toothbrushing, especially the posterior teeth and lingual surfaces. Regular toothbrushing removes only about 35 to 40% of dental plaque present on tooth surfaces. In addition, chewing gum is especially advantageous during the course of the day when toothbrushing is not possible or convenient.
Beneficial effects of gum chewing include increased saliva production. Saliva acts a buffer against the acid produced by bacteria in the mouth that breaks down tooth enamel producing cavities. Saliva also combats the demineralizing effect of the acid in that tooth strengthening minerals are dissolved in it. As the saliva bathes the teeth, the minerals act to remineralize tooth structure that was demineralized by acid. In addition, increased saliva flow can assist in loosening and removing debris from teeth, and can be beneficial to xerostomia patients.
The focus of chewing gum research to date has been on “sugar-free” products, which contain sweeteners such as sorbitol or xylitol. These sweeteners are not broken down by plaque or oral microorganisms to produce acid. Studies have shown these sweeteners act to combat the acidic environment produced by bacteria. In addition, gums containing xylitol have shown anticaries (anticavity) activity in several long-term studies. Chewing a sorbitol-based chewing gum after meals significantly reduced dental caries incidence in a three-year study.