The use of toothbrushes in daycare centers has been questioned because of the possibility of infections spreading through unsupervised brushing. Several field studies have demonstrated a caries-preventive effect of xylitol chewing gum--a measure that could be a practical way of taking care of oral hygiene during daycare hours without brushing. A community trial was conducted in Savonlinna, Finland to test the caries-preventive effect of xylitol chewing gum at these centers. A total of 921 children were recruited. The daycare centers were randomly distributed to xylitol chewing gum or brushing groups. An additional 270 children who had not been in daycare centers were later organized into an external reference group in order to check whether the children in the daycare centers were representative of all children in Savonlinna. The results revealed a statistically significant but clinically small difference between the xylitol and brushing groups in favor of the xylitol group. Many families used the daycare services irregularly. Changes in workplace, periods of unemployment, the birth of other children in the family, etc., affect the likelihood of families keeping their children in a daycare center for many years. Despite the fact that conditions were not optimal, oral health status in the xylitol group was a little bit better than in the control group. The use of xylitol can therefore be recommended, especially if the personnel do not have the possibility to supervise the brushing.