The Science

Foods which lower oral pH below 5.5, known as the ‘critical pH,’ can negatively impact oral health, as enamel becomes demineralized due to acid production when fermentable carbohydrates are metabolized. Remineralization occurs when the plaque pH rises.¹

The period of time taken to return to resting pH levels is influenced by a number of factors, including the buffering capacity of saliva, which varies according to the volume of saliva in the mouth and the rate of flow.² Saliva is essential for the preservation of tooth health by providing the minerals necessary for remineralization;³ if the salivary flow is reduced, plaque pH may remain depressed for a considerable time, leading to the formation of caries.⁴

The concentrations of ions which make up the lattice structure of hydroxyapatite (Ca2+, PO4 3-, OH-) are higher in stimulated than in unstimulated saliva; thus stimulated saliva is a more effective medium for remineralizing enamel crystals damaged by initial acid exposure. In an in situ caries study by Leach et al.⁵ subjects chewed sorbitol gum for 20 minutes after meals and snacks (five times daily). The gain or loss of mineral content of human enamel slabs, bearing artificial lesions and mounted intra-orally for 3 weeks, was then measured and compared with results after similar periods without gum chewing. Remineralization of the enamel lesions occurred both with and without gum, but with gum the remineralization was approximately doubled.

A similar experiment demonstrated that, even with sucrose gum, remineralization was significant with a 30 minute chewing period, but not after a 20 minute chewing period.⁶ Furthermore, the use of sugar-free gum has been associated with a reduction in the quantity and development of plaque,⁷ and a reduction in the acid-forming ability of plaque.⁸

Published Research