The main objective of this study is to evaluate the clinical efficacy of low-level laser therapy (LLLT) in addition to non-surgical periodontal treatment in patients with peri-implantitis. The study aims to investigate the anti-inflammatory and regenerative effects of low-level laser therapy on peri-implant soft and hard tissues and to reveal its contribution to treatment success.

In this context, the specific objectives of the study are as follows:

1. To evaluate the effects of LLLT added to non-surgical mechanical treatment on clinical parameters such as plaque index, probing depth, bleeding index, and clinical attachment level.
2. To examine the contributions of laser therapy to tissue healing by analyzing biochemical markers in peri-implant sulcular fluid over time.

This study will include volunteers who were diagnosed with peri-implantitis based on clinical and radiological examinations at the Department of Periodontology, Faculty of Dentistry, Hatay Mustafa Kemal University.

Seventy-two patients will be included in the study. In our study, patients will be divided into two groups. Thirty-six patients in the test group will receive low-level laser therapy in addition to non-surgical periodontal treatment. Thirty-six patients in the control group will receive only non-surgical periodontal treatment.

Periodontal indexes including plaque index, gingival index, bleeding on probing, probing pocket depth, and clinical attachment level will be recorded and peri-implant sulcus fluid will be collected from patients for routine diagnostic procedures. These measurements will be performed at baseline and at 1.5th and 3rd months by same researcher.

The following are required for a diagnosis of peri-implantitis:

1. Evidence of visual inflammatory changes in the soft tissues around the implant, accompanied by bleeding and/or suppuration during probing
2. Increased probing pocket depths compared to measurements obtained during the placement of the superstructure; and
3. Progressive bone loss according to radiographic bone level assessment within 1 year after delivery of the implant-supported prosthetic reconstruction; and
4. In cases where initial radiographs and probing depths are not available, a radiographic bone level of ≥3 mm and/or probing depths of ≥6 mm, along with the presence of bleeding, indicates peri-implantitis.

Study Treatment Protocol:

In the test group diagnosed with peri-implantitis, low-level laser therapy (LLLT) will be administered three times (on the same day as the initial treatment, on the 3rd day, and on the 7th day) in addition to non-surgical periodontal treatment by using A 940 nm indium gallium arsenide phosphor diode laser (Epic Biolase, Irvine, CA, USA).

PIOS regenerative (periostin) and inflammatory (vascular endothelial growth factor (VEGF), and interleukin-1 beta (IL-1ß)) biomarkers will be analyzed biochemically using the ELISA method (Enzyme-Linked Immunosorbent Assay) at the Department of Biochemistry, Faculty of Medicine, Hatay Mustafa Kemal University.

Inclusion Criteria:

• The patient must be willing to participate in the study.
• At least one implant with a pocket depth ≥ 6 mm and radiographic bone loss ≥ 3 mm diagnosed with peri-implantitis.
• Individuals aged 18-65.
• Patients who can understand and maintain oral hygiene education.

Exclusion Criteria:

• Individuals with any systemic disease that affects periodontal healing (diabetes, cancer, HIV/AIDS, acute infections, liver or kidney dysfunction/insufficiency, autoimmune disorders: rheumatoid arthritis, systemic lupus erythematosus, Hashimoto's thyroiditis)
• Female patients who are pregnant or breastfeeding
• Patients who have undergone periodontal treatment within the last six months
• Patients who have used antibiotics and regular anti-inflammatory medications within the last six months
• Use of medications that affect periodontal tissues (cyclosporine, phenytoin, sodium valproate, etc.).