A biomarker or biological marker is a substance that is objectively measured and evaluated as an indicator of normal biologic process, pathogenic process or pharmacologic responses to a therapeutic intervention. An ideal diagnostic marker should indicate the presence of a disease process before extensive clinical damage has occurred. In the field of periodontology, traditional clinical criteria are often insufficient for determining sites of active disease, for monitoring the response to therapy or for measuring the degree of susceptibility to future disease progression. Biomarkers contribute knowledge about clinical pharmacology and provide a basis for the designing of clinical trials that expeditiously and definitively evaluate safety and efficacy.Researchers in the biotechnology and medical realm are currently investigating the use of oral fluids for the diagnosis of oral and systemic diseases and for drug development. The development of a wide spectrum of marker factors will be a primary goal of periodontal research.