“…Even with these intrinsic weaknesses, field trials are important as they allow the effectiveness and acceptability of preventive agents or methods previously shown in a clinical trial to be effective, to be evaluated in a particular setting. In two of these field trials, xylitol was given as several items of confectionery 17,21 while in other studies, xylitol was given in chewing gum only 20,23,27 and these studies will be considered later.…”