Fig. 4

Periodontal disease biomarkers. Polymorphonuclear (PMN) leukocytes are the first defensive mechanism of periodontal tissues. Multiple products are released during the immunological response. MMP-8 is responsible for breaking type I, II, and III collagens. Several chemicals, including PGE2, IL-1, IL-6, and TNF-α, produced by Mø, fibroblasts, plasma cells, and T lymphocytes, have a role in activating osteoclasts. RANKL stimulates the differentiation of osteoclasts and prevents the programmed cell death of osteoclasts. In normal bodily settings, the RANKL generated by osteoblasts attaches to RANK receptors located on the surface of osteoclast precursors. RANKL is increased by Parathyroid hormone (PTH) and IL-1. Osteoprotegerin (OPG) is synthesized by fibroblasts and serves as a decoy receptor for RANK, hence suppressing osteoclastic activation. Abbreviations: IL-1 β represents interleukin -1, TNF-α stands for tumor necrosis factor α, PGE2 denotes prostaglandin E2, RANKL refers to receptor activator of nuclear factor kappa-B ligand, and OPG represents OPG [104, 105]