MPO and periodontal disorder: Significant correlations were observed (p < 0.01) between salivary MPO activity and severity of periodontal diseases as measured by the clinically periodontal parameters: GI (r = 0.632, p < 0.001), BOP (r = 0.599, p < 0.001), PD index scores (r = 0.179, p = 0.164), and CAL index scores (r = 0.357, p = 0.004) (Figure 2).