Inclusion Criteria:  age of ≥ 30 years; ≥ 20 natural teeth; and chronic-periodontitis (≥ 3 mm of CAL and PD pocket depth respectively on at least 30% of dental sites).  Exclusion Criteria:  chronic systemic diseases; PD therapy during last 6 months; habitual use of chewable and non-chewable tobacco (smoking); alcohol consumers; or use of particular medications during last three months (steroidal and non-steroidal drugs/ anti-biotic/ anti-depressants)