The use of sugar-free gum provides a proven anti-caries benefit, but other oral health effects are less clearly elucidated. Chewing sugar-free chewing gum promotes a strong flow of stimulated saliva, which helps to provide a number of dental benefits: first, the higher flow rate promotes more rapid oral clearance of sugars; second, the high pH and buffering capacity of the stimulated saliva help to neutralise plaque pH after a sugar challenge; and, lastly, studies have shown enhanced remineralisation of early caries-like lesions and ultimately prospective clinical trials have shown reduced caries incidence in children chewing sugar-free gum.
This paper reviews the scientific evidence for these functional claims and discusses other benefits, including plaque and extrinsic stain reduction, along with the possibility of adding specific active agents, including fluoride, antimicrobials, urea and calcium phosphates, to enhance these inherent effects. The evidence for a specific effect of xylitol as a caries-therapeutic agent is also discussed. In conclusion, it is asserted that chewing gum has a place as an additional mode of dental disease prevention to be used in conjunction with the more traditional preventive methods.
Clinical studies have demonstrated the caries promoting effects of sugar based gum when compared with non sugar chewing controls. Sucrose gum has been shown to stimulate plaque growth and increase its adhesivity. Acid produced in plaque and mixed saliva whilst chewing sugar gum is counteracted by the buffering action of mastication induced saliva.
However the vast majority of studies measuring plaque pH has demonstrated acidification of plaque during use of sugar gum into the decalcifying zone (pH < or = 5.5), or after the gum is taken out. Sugar gum causes a more pronounced fall in plaque pH in individuals with an increased caries risk compared to the pH drop in more caries resistant individuals. Sorbitol, by itself or in combination with mannitol is slowly converted to acids by the plaque microorganisms.