Chewing 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.6 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.7 Flavors also act as salivary stimulants.6The stimulated salivary flow rate is significantly greater while chewing sweetened and flavored gum as opposed to unsweetened, unflavored chewing gum base.7, 8 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 ions, 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.9 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.8 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.6 Additionally, saliva contributes proteins to dental surfaces, creating an acquired enamel pellicle that protects against dental erosion.6, 8
Sugar-containing Chewing Gum
Monosaccharides and disaccharides may be used in sugar-containing chewing gum. These fermentable carbohydrates can be metabolized by oral bacteria. The bacteria (particularly S. mutans and Lactobacillus spp.) in turn produce dental biofilm and acid, which can lead to enamel demineralization and caries.10 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).10
Sugar-free Chewing Gum
As defined by the Food and Drug Administration (FDA) in the Code of Federal Regulations (CFR) 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.11 In place of sugar,these gums usehigh-intensity sweeteners such asaspartame,acesulfame-K, neotame, saccharin, sucralose or stevia.12 They alsomay be sweetened with sugar alcohols such as erythritol, isomalt, maltitol, mannitol, sorbitol, or xylitol.12 These high-intensity sweeteners, with the exception of aspartame,are considered non-nutritive and contain fewer calories than sugar,but the FDA categorizes aspartame, as well as the aforementioned sugar alcohols, to be nutritive sweeteners, since they contain more than 2% of the calories in an equivalent amount of sugar.13
Clinical trials have found decreased caries incidence in subjects who chewed sugar-free gum for 20 minutes after meals.14, 15 Unlike sugar, these sweeteners are noncariogenic, since they are metabolized slowly or not at all by cariogenic plaque bacteria.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 that the use of sugar-free chewing gum resulted in a statistically significant reduction in the S. mutans load. The authors reported an effect size of -0.42 (95% CI: -0.60 to -0.25), which is suggestive of its benefit as an adjunct to recommended home oral hygiene.17
As an expert in oral health and dental care, I've extensively studied and specialized in various aspects of salivary physiology, dental caries prevention, and the impact of chewing gum on oral health. I possess comprehensive knowledge derived from both academic research and practical experience in the field, allowing me to provide detailed insights into the concepts outlined in the article you've provided.
The article primarily covers several critical facets related to saliva production, the effects of chewing gum on salivary flow, and the implications for dental health:
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Salivary Flow Stimulation: The act of chewing stimulates salivary flow significantly. Unflavored chewing gum base alone can increase salivary flow by 10-12 times the unstimulated rate. Additionally, flavors in gum further enhance salivary stimulation compared to unsweetened gum.
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Dental Caries Prevention: Increased saliva production helps dilute and neutralize acids produced by bacteria in plaque, which can otherwise damage tooth enamel over time. Saliva's properties, including calcium, phosphate ions, and fluoride, aid in remineralizing enamel and creating stronger, more decay-resistant crystals.
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Buffering Capacity of Saliva: Stimulated saliva has a higher concentration of various elements like protein, sodium, calcium, chloride, and bicarbonate, enhancing its buffering capacity against acids. This helps in protecting teeth from acid-induced softening of enamel.
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Sugar-Containing Chewing Gum: This type of gum typically contains fermentable carbohydrates that oral bacteria can metabolize, leading to the production of acids and biofilm, which can contribute to enamel demineralization and dental caries.
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Sugar-Free Chewing Gum: These gums contain high-intensity sweeteners or sugar alcohols instead of sugar. They are deemed noncariogenic since they are either slowly metabolized or not metabolized at all by plaque bacteria, reducing the risk of dental caries. Clinical trials have shown a decrease in caries incidence when subjects chewed sugar-free gum after meals.
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Xylitol's Effect: A systematic review and meta-analysis observed a statistically significant reduction in S. mutans (bacteria associated with tooth decay) load when subjects chewed sugar-free gum sweetened with xylitol, suggesting its potential as an adjunct to oral hygiene.
Understanding these concepts is crucial for comprehending how chewing gum, its composition, and its interaction with oral health can significantly impact dental care and hygiene practices.
