There is another recent news report concerning the role of xylitol in preventing dental caries. This follows the big news coverage from January 2013, detailing the results of the XACT clinical trial. That study was published in JADA and set off a firestorm of reporting. In that university-based, multi-site study of adults, the subjects were given 5 xylitol mints per day for 33 months and then their decay incidence was followed. There was not difference in outcome with the xylitol group versus the control group. The authors’ conclusion was “These results suggest that xylitol used as a supplement in adults does not reduce their caries experience significantly.”

 

The results of that study were widely reported by the media, focusing on the fact that xylitol had no effect on decay. However, the second paper from that study went largely un-noticed. It was published in the Journal of Dental Research in June of 2013 with the authors concluding “Participants in the xylitol arm developed 40% fewer root caries lesions (0.23 D2FS/year) than those in the placebo arm. Among these caries-active adults, xylitol appears to have a caries-preventive effect on root surfaces.” Just 5 xylitol mints per day reduced the incidence of root surface lesions by 40%. Xylitol by itself may not have much effect in dental caries in a population study, but targeted to patients that have specific risk factors, it has a great outcome. This went un-reported.

 

 

Now fast-forward to 2015, the Cochrane Group, a very well respected organization that takes large groups of studies on a particular topic and pools the data to determine the outcome, did such a meta-analysis on xylitol and dental caries. The problem they encountered was there were only two studies that were designed similar enough to be included in the analysis, and they were performed by the same researchers. In those studies, the xylitol added to fluoride toothpaste showed a 13% reduction in decay rate of the test group over just fluoride alone. The conclusion was the analysis consisted of low quality evidence, and not enough data to make claims on. I would interpret that result to mean just that, we’re not certain from the limited scope of the Cochrane report to make a conclusion. I would be cautious to claim that xylitol has no effect. Lack of limited evidence does not necessarily mean lack of effect.  However, once again the media picks up the information and blasts the public with headlines like:

Evidence of xylitol’s cavity-preventing benefits lacking and Xylitol sweetener may not reduce risk of cavities, or my personal favorite Effect of natural sweetener xylitol in preventing tooth decay is still unproven.

 

What we do know is that there is a compelling amount of evidence that xylitol chewing gum significantly reduces the transmission of Mutans streptococci from mother to child.^1-5 That’s a very good thing, particularly in mothers with high caries risk. We know that xylitol potentiates even small amounts of fluoride.⁶ We also know that combining strategies or therapeutic measures, may have a greater outcome than the sum of the parts.^7,8 We also know that xylitol does not promote dental caries, and both the AAPD and FDA recognize that. So based on all of the available scientific evidence, I think it makes sound judgment to continue using xylitol in managing dental caries, but it should be used in conjunction with other strategies and not depended on as a stand-alone therapy.

 

 

References

1. Thorild I, Lindau B, Twetman S. Caries in 4-year-old children after maternal chewing of gums containing combinations of xylitol, sorbitol, chlorhexidine and fluoride. Eur Arch Paediatr Dent December 2006. 7(4):241-5.
2. Alamoudi NM, Hanno AG, Masoud MI. Effects of xylitol on salivary mutans streptococcus, plaque level, and caries activity in a group of Saudi mother-child pairs. An 18-month clinical trial. Saudi Med J. 2012 Feb;33(2):186-92.
3. Shinga-Ishihara C, Nakai Y, Milgrom P, et al. Xylitol carryover effects on salivary mutans streptococci after 13 months of chewing xylitol gum. Caries Res. 2012;46(6):519-22.
4. Lin HK1, Fang CE, Huang MS, Cheng HC, Huang TW, Chang HT, Tam KW. Effect of maternal use of chewing gums containing xylitol on transmission of mutans streptococci in children: a meta-analysis of randomized controlled trials. Int J Paediatr Dent. 2015 Feb 13. doi: 10.1111/ipd.12155. [Epub ahead of print]
5. Nayak PA, Nayak UA, Khandelwal V. The effect of xylitol on dental caries and oral flora. Clin Cosmet Investig Dent. 2014 Nov 10;6:89-94. doi: 10.2147/CCIDE.S55761. eCollection 2014
6. Maehara H, Iwami Y, Mayanagi H, Takahashi N. Synergistic inhibition by combination of fluoride and xylitol on glycolysis by mutans streptococci and its biochemical mechanism. Caries Research November December 2005. 39(6):521-528.
7. Cheng J, Chaffee BW, Cheng NF, Gansky SA, Featherstone JDB. Understanding Treatment Effect Mechanisms of the CAMBRA Randomized Trial in Reducing Caries Increment. J Dent Res. 2014 Oct 29
8. Office of the US Surgeon General, National Center for Injury Prevention and Control, NIMH, CMHS, 2001. Youth violence. Chapter 5. Rockville, MD. http://www.ncbi.nlm.nih.gov/books/NBK44295