Periodontitis is a chronic inflammatory disease caused by mixed infections with the subgingival microbiota being organized as a biofilm that, if untreated, may result in breakdown of the periodontal tissues in susceptible individuals. Evidence from intervention studies shows that mechanical root debridement significantly improves periodontal health by halting the progression of periodontal tissue breakdown. In order to improve effectiveness and efficacy of the removal of the subgingival biofilm, Er:YAG laser therapy has recently been recommended as an alternative to conventional scaling procedures.

Inclusion Criteria:

Greater than 25 years, Clinical diagnosis of moderate to advanced chronic periodontitis, Pocket depth ≥ 5 mm or clinic attachment level ≥ 4 mm at least in two interproximal areas (not on the same tooth), Along with very good oral hygiene scores (GI≤1and PI≤1), At least 4 teeth in each quadrant, Teeth with subgingival plaque sample is collected has no restoration or prothesis

Exclusion Criteria:

Periodontal treatment ( root planning or surgical periodontal treatment) had done before, Systemic disease that could influence the outcome of periodontal therapy, Prophylaxis regime mandatory during periodontal treatment, Use of any drug that could influence the outcome of periodontal therapy, Use of antibiotics within the last 3 months, Use of anti-inflammatory drugs within the last 3 months, Use of removable prothesis Pregnancy, lactation or use of hormone contraceptives, Smoking