The general consensus among dental researchers is that artificial sweeteners, known as non-nutritive sweeteners (NNS), do not cause dental decay in the same manner as traditional sugar. Non-nutritive sweeteners, which include compounds like sucralose, aspartame, and saccharin, are food additives that provide a sweet taste without contributing significant calories. Their primary benefit for oral health is directly related to how they interact with the bacteria naturally present in the mouth.
The Process of Dental Decay
Dental decay, also called dental caries, is initiated by specific types of oral bacteria, predominantly Streptococcus mutans. These microorganisms naturally reside in the plaque biofilm that forms on the surface of teeth. Cavity formation begins when these bacteria consume fermentable carbohydrates, such as sucrose, glucose, and fructose, left behind by food and drinks.
The metabolism of these sugars produces acidic byproducts, most notably lactic acid. This acid is released directly onto the tooth surface, creating a localized, low-pH environment. When the pH level drops below approximately 5.5, the acid begins to dissolve the mineral structure of tooth enamel, a process known as demineralization. Repeated exposure to these acidic conditions leads to the progressive loss of minerals, eventually resulting in a cavity.
How Artificial Sweeteners Interact with Oral Bacteria
Artificial sweeteners are considered non-cariogenic because the bacteria responsible for decay cannot use them as a food source. Unlike sugars, non-nutritive compounds such as sucralose, acesulfame-K, and aspartame are not fermentable by Streptococcus mutans and related acid-producing bacteria. Since the oral bacteria cannot metabolize the sweetener, the critical step of acid production is bypassed.
The inability of bacteria to ferment these compounds means that consuming non-nutritive sweeteners does not lead to the localized drop in pH required to demineralize enamel. Studies have shown that some NNS, when used in place of sugar, can help maintain microbial equilibrium in the mouth. Certain artificial sweeteners have even been observed to suppress the growth of S. mutans and inhibit their ability to form sticky biofilms on the teeth. This suggests they are not simply inert but may actively reduce the cariogenic potential of the oral environment, offering a protective effect.
pH Levels and Enamel Erosion
While artificial sweeteners do not contribute to decay caused by bacterial acid, the direct impact of external acids is a significant factor in oral health. This issue is known as dental erosion, which is distinct from the bacterial process of decay. Erosion occurs when acids from food or beverages directly dissolve the tooth enamel, independent of bacterial activity.
Many sugar-free or diet products, particularly carbonated sodas and flavored waters, contain added acids to enhance flavor or act as a preservative. Common examples include citric acid, phosphoric acid, and malic acid. These ingredients can lower the product’s pH to levels highly corrosive to enamel. Consuming these acidic products frequently can lead to the direct softening and wear of the tooth surface, regardless of the sweetener used. Therefore, the risk of erosion from a diet cola is due to its low pH, not the artificial sweetener it contains.
Comparing Artificial Sweeteners to Sugar Replacements
When considering alternatives to sugar for dental health, it is helpful to compare non-nutritive sweeteners with sugar alcohols. Sugar alcohols, such as xylitol, sorbitol, and erythritol, provide sweetness but are only partially metabolized by oral bacteria. They are considered non-cariogenic because they do not cause the same dramatic acid production as table sugar.
Some sugar alcohols, particularly xylitol, are recognized for having a specific anti-cariogenic benefit. Xylitol actively inhibits the growth of S. mutans and reduces the bacteria’s ability to adhere to the tooth surface. Erythritol is also highly regarded for its low-calorie count and its minimal impact on oral bacterial activity. While non-nutritive sweeteners like sucralose are beneficial because they are inert, sugar alcohols like xylitol and erythritol can be more advantageous because they actively interfere with the decay process. Choosing these non-sugar options over fermentable sugar offers a clear benefit for protecting tooth enamel.