Microbiology and Immunology 6400 Oral Intermicrobial Interactions Practice Test 2026 – The Complete Guide to Mastering Your Exam!

Progression of periodontal bone loss is driven by a shift in the RANKL-OPG axis toward more RANKL signaling relative to OPG. RANKL binds RANK on osteoclast precursors to promote their formation and activity, leading to bone resorption. OPG acts as a decoy receptor that blocks RANKL from binding RANK. In periodontal disease, inflammatory signals upregulate RANKL and downregulate OPG, tipping the balance so osteoclast activity increases and bone is lost. If RANKL activity were not elevated relative to OPG, or if OPG were higher, resorption would be limited.