Remineralizing Tooth Enamel
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
1. Hicks J, Garcia-Godoy F, Flaitz C. Biological factors in dental caries enamel structure and the caries process in the dynamic process of demineralization and remineralization (part 2). J Clin Pediatr Dent. 2004;28:119–24.View abstract (Opens in a new tab)
2. Bowen WH. The Stephan Curve revisited. Odontology. 2013 Jan;101(1):2-8.View abstract (Opens in a new tab)
3. Pitts NB et al. Dental caries. Nat Rev Dis Primers. 2017 May 25;3:17030.View abstract (Opens in a new tab)
4. Närhi TO, Meurman JH, Ainamo A. Xerostomia and hyposalivation: causes, consequences and treatment in the elderly. Drugs Aging. 1999 Aug;15(2):103-16.View abstract (Opens in a new tab)
5. Leach SA, Lee GT, Edgar WM. Remineralization of artificial caries-like lesions in human enamel in situ by chewing sorbitol gum. J Dent Res. 1989;68:1064–8.View abstract (Opens in a new tab)
6. Manning RH, Edgar WM. Salivary stimulation by chewing gum and its role in the remineralization of caries-like lesions in human enamel in situ. J Clin Dent. 1992;3:71–4.View abstract (Opens in a new tab)
7. Keukenmeester RS et al. The effect of sugar-free chewing gum on plaque and clinical parameters of gingival inflammation: a systematic review. Int J Dent Hyg. 2013 Feb;11(1):2-14.View abstract (Opens in a new tab)
8. Söderling E, Mäkinen KK, Chen CY, Pape HR Jr, Loesche W, Mäkinen PL. Effect of sorbitol, xylitol, and xylitol/sorbitol chewing gums on dental plaque. Caries Res. 1989;23:378–84.View abstract (Opens in a new tab)
The latest research on sugar-free gum
Two recent systematic reviews published by King’s College have concluded that the regular use of polyol combination chewing gum leads to a reduction in dental caries and is an effective addition to oral health regimens.