Sugar-containing Chewing Gum
Sucrose, a disaccharide, is commonly used in sugar-containing chewing gum. Sucrose and other fermentable carbohydrates can be metabolized by oral bacteria. These bacteria (particularly S. mutans and Lactobacillus spp.) produce dental biofilm and acid, which can lead to enamel demineralization and caries.7 The potential cariogenicity of sugar-containing gum depends on the physical consistency, oral retention time of the gum, the frequency with which it is chewed, and the sequence of consumption (for instance, chewing sugar-containing gum before eating foods that reduce acid production will be less cariogenic than the reverse).7
Sugar-free Chewing Gum
As defined in the Code of Federal Regulations 101.60(c )(21CF 101.60(c )), a food or food substance such as chewing gum, can be labeled as “sugar-free” if it contains less than 0.5 g of sugars per serving. In place of sugar, high-intensity sweeteners such as acesulfame-K, aspartame, neotame, saccharin, sucralose or stevia are used to sweeten gum.8 Gum may also be sweetened with sugar alcohols such as erythritol, isomalt, maltitol, mannitol, sorbitol, or xylitol.8 Unlike sugar, these sweeteners are noncariogenic, since they are metabolized slowly or not at all by cariogenic plaque bacteria.9 These sweeteners contain fewer calories than sugar, but the U.S. Food and Drug Administration (FDA) categorizes aspartame and all of the aforementioned sugar alcohols to be nutritive sweeteners since they contain more than 2% of the calories in an equivalent amount of sugar.10
Chewing sugarless gum after a meal can increase salivary flow by stimulating both mechanical and taste receptors in the mouth. The average unstimulated salivary flow rate for healthy people is 0.3-0.4 mL/min.11 The physical act of chewing stimulates salivary flow: simply chewing unsweetened, unflavored chewing gum base stimulates the salivary flow rate by 10-12 times that of the unstimulated rate.12 Flavors also act as salivary stimulants.11 The stimulated salivary flow rate is significantly greater while chewing sweetened and flavored gum as opposed to unsweetened, unflavored chewing gum base.12, 13 Increasing saliva volume helps to dilute and neutralize acids produced by the bacteria in plaque on teeth. Over time, these acids can damage tooth enamel, potentially resulting in decay.
There are several mechanisms by which stimulated saliva flow may protect against dental caries. Increased saliva flow carries with it calcium and phosphate which can contribute to remineralization of tooth enamel; the presence of fluoride in the saliva can serve to replace enamel components magnesium and carbonate with the stronger, more caries-resistant fluorapatite crystals.14 Saliva can buffer the effects of acids in foods or drinks that could otherwise soften teeth’s enamel surface, and swallowing excess saliva created by stimulation clears acid.13 While unstimulated saliva does not have a strong buffering capacity against acid, stimulated saliva has higher concentrations of protein, sodium, calcium, chloride, and bicarbonate increasing its buffering capacity.11 Additionally, saliva contributes proteins to dental surfaces, creating an acquired enamel pellicle that protects against dental erosion.11, 13 Clinical trials have found decreased caries incidence in subjects who chewed sugarless gum for twenty minutes after meals. 15, 16
A 2021 systematic review and meta-analysis by Nasseripour et al.17 examined the use of sugar-free gum sweetened with xylitol and reported the use of sugar-free chewing gum resulted in a statistically significant reduction in the S. mutans load. This association between cariogenesis and S. mutans, the -0.42 effect size (95% CI: -0.60 to -0.25) is suggestive of benefit as an adjunct to recommended home oral hygiene.17