NOS3 and Gingival bleeding: These chemical species augment inflammation and alveolar bone destruction by reducing endothelial nitric oxide synthase expression and expressing pro-inflammatory cytokines [such as tumor necrosis factor-alpha, interleukin (IL)-6 and IL-1β].17-19 In addition, nicotine in tobacco has been reported to produce vasodilation in the gingival circulation of periodontal tissues.10 This seems to be a possible justification for the enhanced BOP and self-perceived gingival bleeding among NW compared to controls.