Periodontitis is a chronic inflammatory disease associated with dental plaque and characterized by the progressive destruction of the tooth-supporting tissues. The principal features of periodontitis include clinical attachment loss (CAL), alveolar bone loss, periodontal pocket formation, gingival bleeding, and the subsequent loss of periodontal tissue support.

The current gold standard for the management of periodontal disease comprises oral hygiene instruction (OHI), non-surgical periodontal therapy (NSPT), periodontal surgery when indicated, and supportive periodontal therapy (SPT). In addition, various antimicrobial agents are used as adjuncts to periodontal treatment. One such agent, hypochlorous acid (HOCl), is a potent antimicrobial with high affinity against Gram-negative bacteria within the subgingival biofilm. Hypochlorous acid is commercially available in mouthwash and spray formulations, which patients may use as adjunctive therapies following periodontal treatment.

In the present project, hypochlorous acid will be applied by the clinician using a dental device during periodontal treatment in a clinical setting. Changes in both clinical and biochemical outcomes, including high-sensitivity C-reactive protein (hs-CRP), C-reactive protein (CRP), antistreptolysin O (ASO), and oncostatin M (OSM), will be recorded and compared with those obtained following conventional periodontal treatment performed using purified water.

The novelty of the proposed study lies in the first-time use of hypochlorous acid as an irrigant in place of purified water during scaling and root planing (SRP), with the aim of evaluating its effects on both clinical and biochemical parameters. This project is expected to attract the attention of researchers investigating the treatment of periodontitis and may facilitate publication in high-impact international peer-reviewed journals as well as presentation at prestigious scientific congresses. Furthermore, it will contribute to the training of qualified researchers in periodontology and support the completion of a doctoral dissertation. The findings may also provide preliminary data for future studies aimed at developing hypochlorous acid-based adjunctive therapeutic approaches for the management of periodontitis.

Periodontitis is a chronic inflammatory disease that may ultimately lead to tooth loss as a consequence of bacterial-induced destruction of the periodontal tissues. It is characterized by an inflammatory response to dental plaque within the periodontal connective tissue and alveolar bone, and the nature and magnitude of this host response largely determine disease progression. Scaling and root planing (SRP) is considered the gold standard for the treatment of periodontitis. The cornerstone of non-surgical periodontal therapy is the mechanical removal of microbial biofilm and calculus through SRP. However, SRP alone may not be sufficient to eliminate pathogenic bacteria, as these microorganisms can persist within the gingival tissues and in anatomical areas that are difficult to access using conventional periodontal instrumentation, including deep periodontal pockets, furcation involvements, interproximal areas, and root concavities. Therefore, local or systemic antimicrobial agents and antiseptics have been recommended as adjunctive therapies to improve periodontal treatment outcomes.

Owing to its antimicrobial, anti-inflammatory, and wound-healing properties, hypochlorous acid is currently used in various dental applications, including biofilm eradication, mouth rinses, wound care, endodontic irrigation, root surface conditioning, and the treatment of peri-implantitis.

This study has been designed as a single-center, randomized, controlled, prospective clinical trial to be conducted at the Department of Periodontology, Faculty of Dentistry, Atatürk University. A total of 44 systemically healthy individuals aged 18-65 years diagnosed with Stage I or Stage II periodontitis will be enrolled in the study.

Participants will be randomly allocated into two groups using a coin-toss randomization method:

Test group: Scaling and root planing (SRP) performed using hypochlorous acid. Control group: Scaling and root planing (SRP) performed using purified water.

All participants will receive standardized oral hygiene instructions at baseline. SRP will be performed using an ultrasonic device, with hypochlorous acid as the irrigating solution in the test group and purified water in the control group.

Clinical periodontal parameters will be recorded at baseline and at the 1-month and 3-month follow-up visits. These parameters will include:

Plaque Index (PI) Probing Pocket Depth (PPD) Bleeding on Probing (BOP) Clinical Attachment Level (CAL)

At the same time points, blood and saliva samples will be collected for the analysis of C-reactive protein (CRP), high-sensitivity C-reactive protein (hs-CRP), oncostatin M (OSM), and antistreptolysin O (ASO) using enzyme-linked immunosorbent assay (ELISA).

The primary objective of this study is to evaluate the clinical efficacy of hypochlorous acid as an adjunct to scaling and root planing. The secondary objective is to investigate its effects on systemic inflammatory biomarkers.

The findings of this study are expected to contribute to the current understanding of adjunctive therapeutic strategies in periodontal treatment and to support the clinical application of hypochlorous acid as a practical and effective adjunctive approach in the management of periodontitis.

Inclusion Criteria:

1. Individuals aged 18 to 65 years.
2. Systemically healthy individuals.
3. Diagnosis of Stage I or Stage II periodontitis according to the 2017 Classification of Periodontal Diseases.
4. Probing pocket depth (PPD) ≤5 mm and clinical attachment loss (CAL) ≤4 mm.
5. Presence of a sufficient number of teeth for periodontal evaluation.
6. Willingness to participate and ability to provide written informed consent.

Exclusion Criteria:

1. Patients with contraindications to the use of ultrasonic instrumentation.
2. Pregnant or lactating women.
3. Patients receiving anti-inflammatory or antibiotic therapy.
4. Patients with systemic diseases or medical conditions.
5. Patients receiving continuous medication for any medical condition.
6. Patients who have undergone periodontal treatment within the previous 6 months.
7. Patients presenting with acute dental pain (e.g., pulpitis or apical/periodontal abscess).
8. Individuals who smoke or consume alcohol.
9. Presence of fewer than 15 teeth.

Individual participant data (IPD) will not be shared due to confidentiality and privacy considerations. As this is a single-center study involving a limited number of participants, no formal data-sharing plan has been established.

The clinical outcome assessor will be blinded to group allocation. The clinician performing the intervention will be aware of the assigned treatment; however, participants will not be explicitly informed of their group allocation.