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New research shows clinical evidence unclear on effects of xylitol products preventing dental caries

March 27, 2015

By Michelle Manchir

Philip Riley

Deborah Moore
Dentists should consider the extent of scientific and clinical evidence before recommending  xylitol products for the purpose of reducing tooth decay, according to research published in March on the Cochrane Library website.
Researchers at the University of Manchester in the United Kingdom concluded that while there is some evidence that using a fluoride toothpaste containing xylitol may reduce tooth decay in the permanent teeth of children by 13 percent over a 3 year period when compared to a fluoride-only toothpaste, the evidence is low quality.
Researchers came to the conclusion after examining information from 4,216 school children who took part in two Costa Rican studies. The researchers also found that for other xylitol-containing products, including syrup, lozenges and tablets, there was little or no evidence of any benefit in preventing tooth decay.
Xylitol has been used as a popular sugar substitute in sweets and is already known to cause less damage to teeth than sugar. It has been suggested that the addition of xylitol to products may help prevent tooth decay by stopping the growth of decay-producing bacteria.
But this review showed "there is insufficient high-quality evidence to prove that xylitol prevents tooth decay, " said the study's lead author, Philip Riley, M.P.H., of the School of Dentistry at the University of Manchester in the United Kingdom in an email. "More well-conducted, randomized placebo-controlled trials that are large enough (in terms of number of randomized participants) to show a difference, if one exists, are needed."
The review, titled "Xylitol-Containing Products for Preventing Dental Caries in Children and Adults" can be read online at www.cochranelibrary.com. Its authors were Mr. Riley, Deborah Moore, M.Sc.; Farooq Ahmed; Mohammad O. Sharif; and Helen V. Worthington, Ph.D..
The review also says that several of the studies included in it did not report sufficient information on the side effects of xylitol, which can include bloating, diarrhea and laxative effects.  Side effects of (sugarless) gum, sweets and other products "should be clearly reported in future studies," Mr. Riley said.
Meanwhile, sugarless varieties of gum and candies are still better than sugar, a proven cariogenic, for patients who want them, Mr. Riley said.  "The best evidence for preventing tooth decay is still brushing with fluoride toothpaste and eating less sugar," he said.
In 2011, the ADA published a clinical practice guideline with a systematic review on non-fluoride caries preventive agents (including xylitol-containing products), which is available here.

The review showed the strength of the recommendation was weak for advising parents and caregivers of children over five years that using sucrose-free polyol (xylitol-only or polyol combinations) chewing gum for 10 to 20 minutes after meals may reduce incidence of coronal caries. For adults, this recommendation was based on expert opinion because the evidence was lacking. The expert panel also advised, based on expert opinion, that the use of xylitol-containing lozenges or hard candies by children five years or older also may reduce the incidence of coronal caries.
The expert panel found that the evidence from the two trials was insufficient to support any statement regarding the caries preventive effects of xylitol in dentifrices.
Other ADA reviews about xylitol are also available at ebd.ada.org.