This paper reports on one of the main goals of preventive dentistry, that is, encouraging children to remove plaque at least once a day. Two self-scoring systems were combined with two disclosants for a total of four experimental systems administered to 128 children. In the count method, the child counts the number of stained teeth; in the rating method, the child selects one of five color photographs that looks most like his own mouth. While both methods appeared to be satisfactory for scoring plaque, the count method does not depend on additional materials and is superior in reliability and teachability. The authors state that while self-scoring systems may not be satisfactory for routine evaluation in a preventive program, they are reasonable substitutes for professional indexes in epidemiological surveys. (Author)