It is the aim of the study to evaluate the efficiency of "One stage full mouth disinfection" according to the original protocol (Quirynen et al. 1995) in comparison to other approaches considering different scaling strategies and different disinfection concepts. Therefore, a multicenter randomized control treatment will be performed. In total, 204 patients with chronic periodontitis shall be allocated to the following treatment concepts. Group A: quadrant scaling with weekly intervals (Q-SRP; N = 51); Group B: full mouth scaling (FMS; N = 51); Group C: full mouth disinfection (FMD; N = 51); Group D: full mouth disinfection with subgingival glycine air polishing using erythritol powder (FMDP; N = 51). Evaluation of periodontopathic parameters and periodontal pathogens at baseline, 3 months and 6 months shall give evidence about the benefits of concept and the single components of FMD.

Inclusion Criteria:

• patients with generalized moderate to severe chronic periodontitis
• presence of at least 18 teeth
• with at least 2 multi-rooted and / or 2 single-rooted teeth in the first quadrant with at least 6 sites with periodontal probing depth of ≥ 6 mm
• radiographic bone loss of at least 25% of the root length

Exclusion Criteria:

• subgingival scaling and root planing within the last 12 months
• antimicrobial rinsing or intake of systemic antibiotics within the last 4 months
• systemic diseases with known interactions to periodontal disease or known need for antibiotic prophylaxis
• known intolerance / allergies to chlorhexidine
• pregnancy

The examiner performing the measurement of all clinical periodontal parameters is not aware of the type of treatment provided to the patient.