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Design of the Xylitol for Adult Caries Trial (X-ACT)

James D Bader1*, Daniel A Shugars1, William M Vollmer2, Christina M Gullion2, Gregg H Gilbert3, Bennett T Amaechi4 and John P Brown4

Author Affiliations

1 Dept. of Operative Dentistry CB#7450, University of North Carolina, Chapel Hill NC 27599-7450 USA

2 Center for Health Research, 3800 N. Interstate Ave, Portland, OR 97227 USA

3 University of Alabama at Birmingham School of Dentistry, 1919 7th Ave S, Birmingham, AL 35233 USA

4 University of Texas Health Sciences Center at San Antonio Dental School, 7703 Floyd Curl Dr., San, Antonio, TX 78229 USA

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BMC Oral Health 2010, 10:22  doi:10.1186/1472-6831-10-22

Published: 29 September 2010



Dental caries incidence in adults is similar to that in children and adolescents, but few caries preventive agents have been evaluated for effectiveness in adults populations. In addition, dentists direct fewer preventive services to their adult patients. Xylitol, an over-the-counter sweetener, has shown some potential as a caries preventive agent, but the evidence for its effectiveness is not yet conclusive and is based largely on studies in child populations.


X-ACT is a three-year, multi-center, placebo controlled, double-blind, randomized clinical trial that tests the effects of daily use of xylitol lozenges versus placebo lozenges on the prevention of adult caries. The trial has randomized 691 participants (ages 21-80) to the two arms. The primary outcome is the increment of cavitated lesions.


This trial should help resolve the overall issue of the effectiveness of xylitol in preventing caries by contributing evidence with a low risk of bias. Just as importantly, the trial will provide much-needed information about the effectiveness of a promising caries prevention agent in adults. An effective xylitol-based caries prevention intervention would represent an easily disseminated method to extend caries prevention to individuals not receiving caries preventive treatment in the dental office.

Trial Registration

ClinicalTrials.Gov NCT00393055