Background: Studies investigating the role of dental plaque in oral disease have focused primarily on the quantity and quality of plaque at a given point in time. No large-scale epidemiologic research has been conducted regarding the continuity and change in plaque levels across the long term and the association of plaque levels with oral health.
Methods: The authors used data from the Dunedin Multidisciplinary Health and Development Study. Collection of dental plaque data occurred at ages 5, 9, 15, 18, 26 and 32 years by means of the Simplified Oral Hygiene Index. The authors assessed oral health outcomes when participants were aged 32 years.
Results: The authors identified three plaque trajectory groups (high, n = 357; medium, n = 450; and low; n = 104) and found substantial, statistically significant differences in both caries and periodontal disease experience among those groups. For example, after the authors controlled for sex, socioeconomic status and dental visiting pattern, they found that participants in the high-plaque-trajectory group lost nearly five times more teeth owing to caries than did those in the low-plaque-trajectory group.
Conclusions: Across the long term, participants in the high-plaque-trajectory group were more likely to experience caries, periodontal disease and subsequent tooth loss than were those in the low- or medium-plaque-trajectory groups, and they experienced all those conditions with greater severity.
Clinical implications: Improving oral health requires emphasizing long-term self-care, as well as providing broad public health and health promotion measures that promote and support oral self-care. This study's findings suggest that poor oral hygiene and smoking have a synergistic effect on periodontal disease experience.