Laird Harrison

June 28, 2012

June 28, 2012 — The food sweetener erythritol may be more effective against caries than its chemical cousin xylitol, researchers reported at the International Association of Dental Research (IADR) 90th General Session and Exhibition, held in Iguacu Falls, Brazil.

In the second long-term randomized controlled trial ever to test erythritol for caries, children who used erythritol for 3 years had fewer decayed surfaces and fewer decayed teeth than children who used xylitol or sorbitol.

The study was based partly at Turku University in Finland, where the landmark Turku Sugar Studies first established xylitol's potential as a caries treatment in the 1970s.

Xylitol has become increasingly available in commercial products as evidence has mounted for its ability to slow decay. Erythritol is much harder to find.

Erythritol belongs in the same family of polyols, also known as sugar alcohols, along with sorbitol, xylitol, maltitol, and several others. However, it was not part of the Turku Sugar Studies.

"It has taken decades after the Turku Sugar Studies to confirm the basic findings of xylitol, which have now been confirmed all over the world," first author Eino Honkala, DDPH, PhD, told Medscape Medical News in an email. "The clinical studies with erythritol have just started."

Sorbitol has generally proved less effective against caries, and most researchers believe this is because Streptococcus mutans can metabolize it.

However, it is not clear whether erythritol works against bacteria in the same way xylitol does, said Dr. Honkala, a professor of dental public health at Kuwait University in Safat. "We need to discover the exact mechanism — how these polyols are affecting oral microbiota," he said.

In addition, a previous long-term clinical trial conducted by researchers at the Carea Joint Municipal Authority for Medical and Social Services on 579 10-year-olds in Kymenlaakso, Kuusankoski, Finland, found no benefit for a combined maltitol/xylitol lozenge over a combined maltitol/erythritol lozenge.

In the new study, researchers from universities in Kuwait, Finland, and Estonia divided 485 first- and second-grade students into 3 groups: erythritol, xylitol, and sorbitol. Each consumed 2.5 g polyol 3 times each day.

After 2 years, and again after 3 years, the researchers found more caries in the dentin of the sorbitol and xylitol groups than in the dentin of the erythritol group.

The study was funded by Cargill R&D Center of Europe, the research arm of Cargill, which makes sweeteners.

The researchers declined to release more detailed data pending publication of their results in a peer-reviewed journal.

Still, the results are promising, Aikja Hietala-Lenkkeri, DDS, told Medscape Medical News. Dr. Hietala-Lenkkeri, the first author of the first long-term erythritol study in caries, said that no firm conclusions could be drawn until more long-term randomized controlled trials are done, but she suggested that clinicians stay tuned.

"Erythritol is a nonlaxative and a noncaloric sugar alcohol, which seems to be a very promising sugar alcohol from a cariological point of view," said Dr. Hietala-Lenkkeri, who was not involved in the study. "It is probable that the eventual future studies on the caries-preventive effect of erythritol will further strengthen and add to the current, yet scant, evidence of this positive effect."

In addition, she argued that the results of her own trial do not mean erythritol is not effective. "In the low-caries-prevalence population living on an area of natural fluoridation and having received comprehensive free routine prevention, additional caries reduction was difficult to achieve," she told Medscape Medical News in an email.

She suggested that clinicians continue to consider using xylitol while more information about erythritol emerges.

When they do, however, they should also consider the dose that they prescribe, said Donald Chi, DDS, PhD, assistant professor of dental public health at the University of Washington, Seattle, who presented a separate xylitol study at this meeting.

"There is a minimum dose and frequency that's required before we see any benefit," Dr. Chi told Medscape Medical News.

The minimum dose, Dr. Chi says, is 8 to 10 g, given in 2 to 3 doses per day.

However, some commercial xylitol products may not meet that minimum standard, and Dr. Chi and colleagues set out to test whether a commercial toothpaste from Epic Dental, with only .08 g xylitol in a pea-sized amount of toothpaste (.25 g), would have an effect on caries.

The researchers randomly assigned 196 children to use either the Epic Dental xylitol toothpaste or a sorbitol toothpaste (Colgate Total), used as a control. Both toothpastes contained 1400 parts per million of fluoride.

The researchers assumed that the children were brushing twice a day for 12 months, then once a day for 3 months.

They found no significant differences between the 2 groups in the proportion of children with high levels of plaque or salivary S mutans.

The mean increase in the number of carious surfaces (d2-3, or decay in the dentin) increased in the xylitol group to 2.47 and in the sorbitol group to 1.37, but the difference was not statistically significant (P = .06).

"The bottom line is that there was no difference between the kids who got the toothpaste with sorbitol and those who got the toothpaste with xylitol," said Dr. Chi.

Previous studies have shown xylitol to be more effective than sorbitol at high doses.

If Epic could put a lot more xylitol in its toothpaste, it might have an effect, but that could also affect the consistency of the toothpaste, Dr. Chi said.

He recommended that clinicians consider the dose of xylitol products they prescribe.

Dr. Honkala, Dr. Aikja Hietala-Lenkkeri, and Dr. Chi have disclosed no relevant financial relationships.

International Association of Dental Research (IADR) 90th General Session and Exhibition: Abstract 1151, presented June 21 and abstract 3029, presented June 23, 2012.

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