Periodontitis is a chronic inflammatory disease affecting the supporting structures of the teeth and is associated with both local tissue destruction and systemic inflammatory responses. Non-surgical periodontal therapy, particularly scaling and root planing (SRP), is the primary treatment approach; however, it may not completely eliminate pathogenic microorganisms in all cases.

Adjunctive antimicrobial agents may improve treatment outcomes by enhancing bacterial reduction and modulating inflammation. Chlorhexidine (CHX) is widely used for its antimicrobial properties, while zinc has anti-inflammatory and immunomodulatory effects. The combined use of CHX and zinc may provide synergistic benefits in periodontal therapy.

The aim of this randomized controlled clinical trial is to evaluate the clinical and biochemical effects of CHX and zinc as adjuncts to SRP in individuals with stage I and II periodontitis.

A total of 44 systemically healthy participants will be randomly assigned to two groups. The test group will receive SRP with CHX and zinc, while the control group will receive SRP with distilled water. Clinical periodontal parameters (Plaque Index, Bleeding on Probing, Probing Pocket Depth, and Clinical Attachment Level) and biochemical markers (C-reactive protein, high-sensitivity CRP, Oncostatin M, and Antistreptolysin O) will be evaluated at baseline, 1 month, and 3 months.

The results of this study are expected to provide evidence regarding the potential benefits of CHX and zinc in improving periodontal treatment outcomes and reducing systemic inflammation.

Periodontitis is a multifactorial chronic inflammatory disease characterized by the destruction of tooth-supporting tissues, including gingiva, periodontal ligament, and alveolar bone. It is initiated by microbial dental plaque and modulated by the host immune response, leading to both local tissue damage and systemic inflammatory effects.

Scaling and root planing (SRP) is the gold standard for non-surgical periodontal therapy and aims to mechanically remove plaque and calculus from root surfaces. However, due to anatomical limitations and microbial persistence in periodontal pockets, SRP alone may not always achieve optimal clinical outcomes. Therefore, adjunctive antimicrobial and anti-inflammatory agents have been proposed to enhance treatment efficacy.

Chlorhexidine (CHX) is considered the gold standard antiseptic in dentistry due to its broad-spectrum antimicrobial activity and substantivity. Zinc, on the other hand, has been shown to possess anti-inflammatory, antioxidant, and immunomodulatory properties. The combination of CHX and zinc may provide a synergistic effect by reducing microbial load while simultaneously modulating the host inflammatory response.

This study is designed as a single-center, randomized, controlled, prospective clinical trial conducted at the Department of Periodontology, Faculty of Dentistry, Ataturk University. A total of 44 systemically healthy individuals aged between 18 and 65 years with stage I and II periodontitis will be included.

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

• Test group: SRP with chlorhexidine and zinc
• Control group: SRP with distilled water

All participants will receive standardized oral hygiene instructions prior to treatment. SRP procedures will be performed using ultrasonic instruments. In the test group, chlorhexidine and zinc solution will be used during the procedure, whereas distilled water will be used in the control group.

Clinical periodontal parameters including Plaque Index (PI), Bleeding on Probing (BOP), Probing Pocket Depth (PPD), and Clinical Attachment Level (CAL) will be recorded at baseline, 1 month, and 3 months. In addition, blood and saliva samples will be collected at the same time points to analyze biochemical markers including C-reactive protein (CRP), high-sensitivity CRP (hs-CRP), Oncostatin M (OSM), and Antistreptolysin O (ASO) using ELISA methods.

The primary objective of this study is to evaluate the clinical effectiveness of CHX and zinc as adjuncts to SRP. The secondary objective is to assess their effects on systemic inflammatory biomarkers.

The findings of this study are expected to contribute to the understanding of adjunctive treatment strategies in periodontal therapy and may support the use of CHX and zinc combination as a practical and effective approach in clinical practice.

Inclusion Criteria:

• Individuals aged between 18 and 65 years
• Systemically healthy individuals
• Diagnosed with Stage I or Stage II periodontitis according to the 2017 classification
• Having probing pocket depth ≤5 mm and clinical attachment loss ≤4 mm
• Having a sufficient number of teeth for periodontal evaluation
• Willing to participate and able to provide informed consent

Exclusion Criteria:

• Presence of systemic diseases affecting periodontal health
• Pregnancy or breastfeeding
• Smoking
• Use of antibiotics or anti-inflammatory drugs within the last 6 months
• History of periodontal treatment within the last 6 months
• Fewer than 15 teeth present
• History of radiotherapy or chemotherapy

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

The clinical outcome assessor is blinded to group allocation. The operator performing the treatment is aware of the intervention, while participants are not explicitly informed about group allocation.