Field trials of preventive regimens in Thailand and French Polynesia.

Field demonstration trials of preventive agents or methods are needed so that the effectiveness and acceptability of such methods can be evaluated when used as part of the prevailing system and life style in a particular community. Agents so tested should have already been shown in a clinical trial to have a positive effect. Field demonstration trials differ from clinical trials in having no traditional control group; the study is not 'blind'; there is no special supervision and there is no special selection of participants. Results of two field demonstration trials, one in a population in Thailand with moderate but increasing caries severity and the other in French Polynesia, where caries severity is very high, are reported. The trials compared the effectiveness of various chewing gum formulations with the effectiveness of a fortnightly supervised sodium fluoride rinse. One gum formulation contained fluoride and was sweetened with sucrose or xylitol and sorbitol, the other was fluoride free and was sweetened with xylitol and sorbitol. The important information from these field trials is that a fluoride-containing chewing gum sweetened with xylitol/sorbitol appears to be effective in controlling caries experience even in communities apparently experiencing an increase of the disease; and that the apparent effectiveness was achieved in a field situation subject to all the problems of a programme not under a rigid clinical trial type of control. The fluoride-containing chewing gum-sucrose regime, in both the trials, and the non-fluoride chewing gum-xylitol/sorbitol regime in the French Polynesia trial failed to exhibit any notable preventive effect.