This clinical trial is studying whether using erythritol powder during non-surgical periodontal treatment (deep cleaning) helps improve gum health in people with severe periodontitis. Participants with deep gum pockets (4 mm or more) receive standard treatment alone or standard treatment plus cleaning with erythritol powder. The goal is to evaluate if adding erythritol improves outcomes such as healing of gum pockets, bleeding, plaque levels, and gum attachment compared to standard treatment alone.