The effect of toothbrushing frequency, toothbrushing hand, sex and social class on the incidence of plaque, gingivitis and pocketing in adolescents: a longitudinal cohort study.

Reported toothbrushing frequency and the effect of toothbrushing frequency, toothbrushing hand, sex and social class on the incidence of plaque and periodontal disease in a group of 720 adolescents examined at age 11-12 years and again at 15-16 years is presented. At 11-12 years, the mean toothbrushing frequency was 11.5 times per week. By age 15-16 years, it had risen to 13.3 times per week. Children from social class I were less likely to brush once per day or less and more likely to brush twice daily than those from social class V. At both examinations, consistently low negative correlations were seen between reported toothbrushing frequency and the mean scores for buccal and lingual plaque, buccal, mesial and total bleeding. Few significant differences were seen between left- and right-handed toothbrushers at age 11-12 years. These were almost entirely due to differences between the boys. By age 15-16 years, no significant differences existed between the two groups. At both examinations, the boys had higher plaque, bleeding and pocketing scores than did the girls. At 15-16 years of age, all social classes exhibited lower mean total pocketing scores than at age 11-12 years. At 11-12 years of age, the social class differences were mainly contributed by the girls, while at re-examination plaque and bleeding scores for both sexes showed an overall trend to increase from social class I through to social class V. At 11-12 years of age, the boys showed a trend for pocketing to increase from social class I through to social class V. This was absent at 15-16 years of age. The girls showed no such trend at 11-12, but it had emerged by age 15-16. The results again demonstrate the influence of social class and sex rather than toothbrushing frequency and handedness on oral hygiene and gingival health. However, in view of the high number of statistical tests employed, some caution must be exercised in the interpretation of differences significant at the 5 per cent level.