Biomarkers of Periodontal Disease and the Biologic Matrix Conundrum: A Narrative Review

Monitoring periodontal disease using clinical parameters is time-consuming and reflects past destruction only. The clinical measurements are also prone to error with possible inter-examiner variability. Within the scope of current knowledge and understanding of periodontal pathogenesis, biomarkers play a crucial role in revealing ongoing periodontal disease activity. These biomarkers are identified from various biological matrices such as saliva, Gingival Crevicular Fluid (GCF), serum, gingival tissue, or even plaque samples. Most studies have utilised saliva and GCF due to their ease of collection and non invasive sampling to identify biomarkers of periodontal disease activity; consequently, most hypotheses regarding the initiation and progression of periodontal disease have been derived from such studies. Most proteins are secreted by tissues and then seep into GCF and saliva. Therefore, protein expression occurs in the tissues and their amounts in GCF or saliva represent only a small part of the total. The sensitivity of detecting and monitoring a given biomarker in GCF, saliva, or gingival tissue is debatable. The appropriateness of the biological matrix from which the biomarkers have been isolated and identified has not been validated. The present review highlights the need to address the choice of biological matrix suitable for studying biomarkers involved in periodontal disease pathogenesis and summarises promising biomarkers of periodontal disease activity in saliva, GCF and gingival tissues.