Currently, two principal forms of destructive periodontal disease are recognized – chronic periodontitis and aggressive periodontitis – but their distinction in epidemiologic studies has been rather problematic because of substantial overlap of their primary features. This review critically appraises some key features relevant to the epidemiology of human periodontitis that underlie its core ‘identity’ as a bacterial biofilm-induced, inflammatory disease and discusses its impact within the larger context of aging populations. The currently adopted epidemiologic methodologies/definitions that result in the almost ubiquitous prevalence of periodontitis indeed overestimate the occurrence of the disease that may actually put individuals at a true biologic, functional or psychosocial disadvantage. Use of these definitions has inevitably promoted the inference that periodontitis constitutes an insurmountable oral health problem. In contrast, reliance solely on physical measurements of probing depth and/or attachment loss under-recognizes the true impact that periodontitis may have on the well-being of individuals. It is currently unclear whether inclusion of the psychosocial and systemic dimensions of the disease in case definitions would result in higher or lower prevalence estimates. The review concludes that periodontitis should no longer be defined solely by gingival/periodontal inflammation in the presence of increased probing depths and attachment loss but should incorporate additional dimensions capturing impaired function, esthetics, and impact on general health and quality of life. A multidimensional approach to the assessment of periodontitis would facilitate an improved understanding of its epidemiology and consequences.