The implementation of field trials.

Even though a preventive agent has been shown to be powerful in reducing the incidence of, for example, dental caries when tested in a longitudinal clinical trial, it might not be as powerful when tested under more realistic environmental conditions. Field trials or field demonstration programs will provide the final evidence for determining if the agent or procedure is of such practical importance as to be included as a component in a dental care delivery system. The methodology developed for health services research provides the possibility of testing the effectiveness of a single or combined components in a dental care delivery system seen in relation to the environment and conditions under which it operates. The World Health Organization is at present involved in the implementation of a long range of field demonstration programs in various parts of the world especially in developing countries in order to establish the potential of known preventive procedures in population groups with different levels and different progression patterns of oral diseases.