NOS2 and periodontal disorder: Ghosh et al. (2008) demonstrated that NO and its regulatory enzyme iNOS are a key role in the pathogenesis of periodontal disease. Furthermore, diverse studies have reported that high levels of NO and iNOS are relational with periodontal disease severity in patients and rodent models (Menaka et al., 2009; Di Paola et al., 2004; Gyurko et al., 2003).