“…24 A variety of biological processes, eg., antimicrobial defense, inflammation, carcinogenesis, radiation damage, photobiological effects, and aging, involve reactive oxygen species. 25 Reactive oxygen species (ROS) play crucial roles in normal physiological processes including response to growth factors, the immune response, and apoptotic elimination of damaged cells but are also highly toxic and destructive when generated during the respiratory burst as it represents an important pathogenic mechanism for tissue damage and diseases associated with phagocytic insiltration. 26 Excessive production of ROS resulting in oxidative stress has been implicated in the pathogenesis of many human diseases including periodontitis.…”