Xylitol and caries prevention - is it a magic bullet

A new study on xylitol has been published in The British Dental Journal Volume 194 No. 8 April 26th 2003, entitled 'Xylitol and caries prevention - is it a magic bullet' (A.Maguire and A.J. Rugg-Gunn) 

The study concludes that xylitol exhibits dental health benefits which are superior to other polyols in all areas where polyols have been shown to have an effect.  In addition, xylitol's specific effects on oral flora and especially on certain strains of mutans streptococci add to its caries-preventive profile and give it a unique role in preventive strategies for dental health.

Xylitol reduces proportions of mutans streptococci in plaque through non-specific and special effects

Non- specific         
Because Xylitol is non fermentable it does not encourage bacteria growth.

Specific                    
When mutans streptococci are exposed to xylitol they can develop mutant xylitol resistant strains which may be less virulant in the oral environment.     

Exposure of plaque to xylitol leads to an increase in the concentrations of amino acids and ammonia, nutralising plaque acids.

Xylitol can act in a bacteriostatic ways: some strains of oral streptococci take up xylitol convert it to xylito-5-phosphate, resulting in the formation of intra-cellular vacuoles and degraded cell membranes.

Xylitol can cause a 'futile metabolic cycle'.  Streptococcus strains take up xylitol and phosphorylate it to xylitol-5-phosphate.  This is then split by sugar-phosphate phosphatases and the xylitol is then expelled from the cell.