Non-surgical periodontal therapy is a widely adopted procedure for the treatment of periodontitis, particularly in its moderate to severe stages. The approach involves the mechanical and manual debridement of subgingival biofilm and calculus through the use of ultrasonic scalers and hand curettes. This method aims to disrupt the pathogenic bacterial load within periodontal pockets and promote clinical attachment gain while reducing inflammation. However, the mechanical removal of biofilm alone may not always ensure complete bacterial eradication, especially in deep or anatomically complex sites.

To enhance bacterial disinfection and optimize clinical outcomes, the adjunctive use of ozone therapy has been introduced. This is a non-invasive technique that employs ozone in gaseous form to eliminate bacteria and fungi, inactivate viruses, and control bleeding. Its antiviral efficacy results from the denaturation of envelope proteins, impairment of viral adhesion to host cells, oxidation of unsaturated fatty acids within the lipid envelope, and degradation of single-stranded RNA. The synergistic effect of combining conventional non-surgical periodontal therapy with ozone therapy enables more thorough decontamination of periodontal pockets, even in cases where systemic antibiotics prove ineffective.

The aim of this study is to evaluate the clinical efficacy of adjunctive ozone therapy following non-surgical periodontal treatment in patients with severe periodontitis. The protocol consists of initial subgingival instrumentation using ultrasonic and manual tools, followed by the application of ozone therapy. The working hypothesis of this study is that the addition of ozone therapy provides superior bacterial reduction and improved clinical outcomes compared to mechanical therapy alone.

Inclusion Criteria:

Age between 18 and 84 years; Good general health status; Diagnosis of severe periodontitis involving at least 30% of all teeth, with at least three non-adjacent teeth presenting three sites with probing pocket depth (PPD) greater than 4 mm in at least two quadrants, and having lost at least four teeth due to periodontitis; Presence of at least 16 teeth, with a minimum of four teeth per quadrant.

Exclusion Criteria:

Pregnancy or breastfeeding; Presence of decompensated systemic diseases that may compromise the outcomes of the study or the patient's health; Regular use of antibiotics; Regular use of anti-inflammatory drugs (NSAIDs, corticosteroids, or aspirin); Use of anticoagulant medications; History of systemic antibiotic therapy within six months prior to enrollment; History of any periodontal therapy within six months prior to enrollment; Presence of severe mental or cognitive disorders.