Inclusion Criteria:  Untreated patients diagnosed with severe/advanced periodontitis with slow/moderate rate of progression Age > 18 years Patients at least 10 teeth per arch Presence at least of two teeth with PD > 5 mm per quadrant Single-rooted teeth or multi-rooted without furcation involvement  Exclusion Criteria:  Patients with systemic diseases Pregnant or lactating Tobacco smokers (<10 cigarettes/day) Previous periodontal treatment in the last 2 years Prolonged antibiotic treatment or anti-inflammatory treatment within 6 months prior to periodontal therapy Furcation involvement Acute periodontal or endodontic abscesses Third molars