A Steady-state Plaque Environment

Objectives: Alterations of site-specific associations between supragingival plaque and gingival inflammation may be decisive in describing effects of toothpaste or mouthwash compounds. This study describes characteristics of a steady-state plaque environment and variations in site-specific associations in a young adult population with plaque-induced gingivitis. Methods: 40 otherwise healthy, nonsmoking volunteers participated. Age range was 19-28 yr. Examinations included periodontal probing depth (PPD), bleeding index (BI, 0-2), and plaque index (PI, 0-3). Probing was done with a pressure-controlled probe (about 1.27 MPa). Examinations were repeated after 2 and 4 weeks, and participants exhorted not to change their oral hygiene habits. Results: Mean PI did not change (mean 1.1, standard deviation 0.37-0.40). Associations between repeat observations of dichotomized PI were strong: Mantel-Haenszel's common odds ratio (RMH) for first as compared to second examination 12.0, 95% C.I. 10.6-13.6; for first equals second, compared to third examination 26.5, 95% C.I. 22.8-30.8. Intraoral distribution of cumulative mean site PI revealed well-defined, symmetric and consistent distribution of supragingival plaque. Between 18 and 21% sites bled on probing (BOP). Associations between repeat BOP were essentially weaker: RMH 2.41 (2.10-2.76) and 4.56 (3.70-5.61), respectively. No consistent or symmetric pattern was revealed for mean site BI. Longitudinal RMH between BOP and dichotomized PI (0,1 vs 2,3) ranged between 0.7 (i.e., negative association) and 6.2 (median 2.1). Homogeneity tests revealed that only 2 individuals presented with heterogeneous associations (p<0.05). Conclusion: In a steady-state plaque environment in young adults with plaque-induced gingivitis gingival inflammation is only weakly associated with supragingival plaque. Patterns of intraoral gingival bleeding upon probing are inconsistent, not symmetric and may best be described as chaotic. Supported in part by KURA Grant DS02/02.