Does Chewing Gum Containing Xylitol Prevent Your Teeth from Decay?

This article was written with the expert opinion of a consultant (DDS, MPH, Board Certified) on Preventive Dentistry. Edited by: Paula Vasin

In Part I of this investigation, we introduced the topic of tooth decay and the purported role of Xylitol, a natural sweetener, in preventing dental caries. Here, we will evaluate the scientific evidence related to this topic.

Chemical structure of Xylitol, a natural sweetener.

Unfortunately, the outcomes of studies with Xylitol chewing gum (focus of this report) on prevention of dental caries are inconclusive. Some researchers have attributed the inconsistency to the wide variability in and between studies in the conditions under which the gum was tested. A few examples include differences in dosage, frequency, duration, time of use, extent of supervision, and extent of compliance.

Other researchers attribute the inconsistent results to the less than satisfactory quality of the research:

• Randomized Trials: Many studies deviate from the principle requirements of conducting randomized clinical trials (RCT), which follow standards enumerated by the Council on Dental Therapeutics of the American Dental Association.
• Control Groups: A widely held criticism is the failure of many studies to show a specific Xylitol effect when a “no gum” control group is used. Why is this a criticism? Chewing gum has the capacity to stimulate the secretion of saliva, and saliva can prevent drop in pH. The drop in pH creates an acidic environment within the mouth, which can lead to demineralization of enamel and eventually to decay. Therefore, chewing gum, even without Xylitol in it, could result in a decrease in tooth decay. Thus, when a no gum control group is included, the specific effect of Xylitol cannot be examined reliably. In cases when the control group also chews gum, the gum should be completely inactive- meaning it should not have any known effects on tooth decay (positive or negative). For instance, Sorbitol, another type of sweetener, is considered by some researchers to be an invalid control group. In the few studies that have compared Xylitol versus Sorbitol, the results have been mixed.
• Sample Size: The number of subjects that are included in the study (i.e. sample size) is critical. When this number is too large, sometimes a small clinical effect can become statistically significant. Conversely, when the number of subjects enrolled in the study is too small, statistical power may be too low. In this case, negative results are not necessarily evidence that no treatment effect exists.
• Balance of Study Groups: When selecting the initial group of subjects who are planned to be included in the study, the “drop-out” rate should be carefully considered. For instance, a number of individuals may be eliminated from the study due to development of new decay. When these variables are not carefully considered at the time of subject recruitment, the study results (and the final sample size) may be greatly affected.
• Diagnosis: The diagnostic criteria for caries (decay) may be different across studies. For instance, decay could be considered anything from white spot lesions to cavitation. If the decay is in its earliest stages at the start of the study, diagnosis of the change in decay at the end of the study will be more challenging and therefore, small reversals may be missed.

In summary, due to the high variability in study design and the lack of protocol standardization, the current body of evidence about the role of Xylitol in preventing dental caries is inconclusive. There is a need for further RCTs, with better quality and more clearly defined guidelines. With more uniformity in the design and methods, future studies can better determine the effectiveness of Xylitol on tooth decay prevention.

Note: The sources of this report were obtained from a search of PubMed using the terms “Xylitol” and “reviews.” Numerous PubMed-related citations of abstracts of reviews were identified. Those titles that appeared to evaluate evidence of Xylitol’s effectiveness in preventing tooth decay (dental caries) were selected by the author of this report. Thus, it is far from an exhaustive inclusion of the large number of other reviews on this topic.