[Distribution of dental plaque and time analysis of toothbrushing without instruction in school children and students].

The purpose of this study is to evaluate oral hygiene before and after individual method toothbrushing without instruction and to analyze toothbrushing times for school children from 6 to 13 years of age. Subjects were 150 pupils from primary to junior high school affiliated with the faculty of education of an university located in Setagaya, Tokyo: 38 first-grade pupils aged 6, 36 fourth-grade pupils aged 9, 37 sixth-grade pupils aged 11, and 39 second-year junior high school pupils aged 13. Assessments of dental plaque were made by two dentists using the PHP plaque score (Podshadely and Haley, 1968) for primary school pupils and OHI-S (only DI-S; Greene and Vermillion, 1964) for junior high school pupils. Plaque distribution disclosed by an Erythrosine solution was examined before and after toothbrushing, and the performance of toothbrushing by subjects was recorded on video-tape through a one-way mirror so that the children were unaware. Toothbrushing time was measured by 2 or 3 examiners using a time counter of video-monitor. Average scores for dental plaque before and after toothbrushing were almost the same for first and fourth-grade primary school pupils; but scores decreased with a statistically significant difference (p less than 0.01) for sixth-grade pupils. Distribution patterns of plaque scores for fourth-grade pupils showed characteristically narrow ranges (2-5 before brushing and 1-4 after brushing). The majority of subjects (69.4%) had scores of 2-3 after brushing, Whereas only 8.3% showed a range of 2-3 before brushing.(ABSTRACT TRUNCATED AT 250 WORDS)