Study conducted in patients recruited at private praxis setting after completed step 2 periodontal therapy. Residual pockets ≥4mm with positive bleeding or such >5mm randomly allocated to either conventional subgingival re-instrumentation (controls) or to same mechanical treatment with adjectively applied hypochlorite/aminoacid gel for antiseptic reason followed by subginigival placement of cross linked hyaluronic acid gel for sealing the site after instrumentation. Re-evaluations at 3 and 9 months controlled for clinical parameters such as Periodontal Probing Depth (PPD) (CAL), Clinical Attachment Level, Gingival Recession (GR), Bleeding on Probing (BOP). The hypothesis is, sites treated with adjunctive protocol show greater PPD reduction and greater CAL gain at 9-month evaluation.

Inclusion Criteria:

• systemically healthy individuals, smokers and non-smokers, HbA1c <7.5%, compliant and adhering to systematic periodontal treatment protocol incl. SPT visits, patients willing to complete a 9-month post-op observation period

Exclusion Criteria:

• rheumatoid arthritis, HbA1c ≥7.5%, treatment of periodontitis within past 12 months, use of systemic antibiotics in past 6 months, pregnant and lactating individuals