I leave you here a link to the article published in confectionerynews.com where you can see the discussion about the validity of the claim about the value of xylitol as oral care agent.
The article does not deal only about chewing gum. It mentions other products with xylitol (lozenges, toothpaste, …). The conclusion is that the effect is not as proven and clear as other studies suggest. Well… it is always good a bit of discussion and debate…
Chewing Gum Consultant 
Need to discuss Project with you, send across your mail id thanks Lokesh Naidu
My email is joanmestres@hotmail.com