MMP9 and diabetes mellitus: Based on these considerations, in this study we assessed whether the analyzed biomarkers,—osteoprotegerin (OPG), kappa B nuclear factor receptor activator ligand (RANKL), hepatocyte growth factor (HGF), tumor necrosis factor-α (TNF-α), interleukin 18 (IL-18), matrix metalloproteinase 9 (MMP-9) and oxidative stress markers: total oxidant status (TOS), total antioxidant capacity (TAC)—are modified in the saliva of type 2 diabetes mellitus patients compared to healthy individuals pre -and post-dental extraction, and whether they correlate with HbA1c levels.