A prospective, randomized clinical trial with a 3-month duration was designed to evaluate the efficacy of non-surgical treatment for peri-implantitis. Patients presenting at the Postgraduate Periodontology Clinic of the School of Dentistry, Aristotle University of Thessaloniki, with a diagnosis of peri-implantitis in at least one implant (based on the new classification of periodontal and peri-implant diseases, EFP 2018) will be included.

After clinical and radiographic evaluation, patients will be randomly assigned to two groups, with each patient participating in the study with one implant. The control group will receive non-surgical treatment using ultrasonic scalers designed for implants, combined with saline irrigation. The experimental group will undergo non-surgical treatment with Er:YAG (2940nm) and Diode (808nm) laser. All patients will receive oral hygiene instructions at baseline and during each subsequent visit.

Microbial plaque samples will be collected using two sterile paper cones from the deepest peri-implant pocket before treatment and three months after treatment. The presence and absolute counts of Porphyromonas gingivalis and Filifactor alocis will be assessed using quantitative polymerase chain reaction (qPCR). Additionally, peri-implant crevicular fluid will be collected from the second deepest peri-implant pocket using three sterile paper cones before treatment and three months post-treatment for metabolomic analysis.

Clinical parameters, including probing pocket depth (PPD), bleeding on probing (BOP), clinical attachment level (CAL), peri-implant mucosal recession (REC), and suppuration (SUP), will be recorded at baseline and at the end of the experimental period (3 months). Treatment success will be evaluated at the 3-month mark, defined as a pocket depth ≤5 mm with no bleeding on probing at more than one of six implant sites and no suppuration, according to the EFP S3 level clinical practice guideline.

Additionally, patients will complete a home questionnaire to assess pain at different time points (immediately after treatment, 24, 48, and 72 hours post-treatment). Pain levels will be evaluated using a 100-mm visual analog scale (VAS), where 0 mm indicates "no pain" and 100 mm represents "worst pain." The total number of analgesics consumed daily for one week post-treatment will also be recorded. At the end of the week, patients will answer four Yes/No/Don't Know questions to assess their satisfaction with the treatment.

This study aims to compare the effectiveness of non-surgical peri-implantitis treatment using conventional ultrasonic debridement versus a laser-assisted approach. The primary objective is to assess clinical, microbiological, and metabolomic outcomes associated with each treatment modality.

The study will be conducted at the Postgraduate Periodontology Clinic of the School of Dentistry, Aristotle University of Thessaloniki. Participants will be screened based on inclusion and exclusion criteria, and those diagnosed with peri-implantitis in at least one implant will be randomly assigned to either the control or experimental group.

Study Procedures:

Control Group: Treatment with ultrasonic scalers designed for implants and saline irrigation.

Experimental Group: Treatment with Er:YAG (2940nm) and Diode (808nm) laser.

Oral Hygiene Instructions: Provided at baseline and each follow-up visit.

Microbiological Sampling: Collection of subgingival plaque using sterile paper cones before and after treatment (3 months), with analysis of P. gingivalis and F. alocis using qPCR.

Metabolomic Analysis: Collection of peri-implant crevicular fluid before and after treatment for metabolomic profiling.

Clinical Parameters: PPD, BOP, CAL, REC, and SUP will be recorded at baseline and after 3 months.

Pain and Patient Satisfaction: VAS pain assessment at multiple time points and tracking of analgesic consumption. A patient satisfaction questionnaire will be completed at the end of the study.

Study Outcomes:

Primary Outcome: Reduction in peri-implant pocket depth and inflammation.

Secondary Outcomes: Changes in microbiological and metabolomic markers, pain perception, and patient-reported satisfaction.

This randomized controlled clinical trial aims to provide valuable insights into the efficacy of laser-assisted non-surgical therapy for peri-implantitis compared to conventional ultrasonic debridement. The findings could contribute to the optimization of non-surgical treatment protocols for peri-implant disease management.

Inclusion Criteria:

• Patients presenting at the Postgraduate Periodontology Clinic with a diagnosis of peri-implantitis in at least one implant, based on the 2018 Classification of Periodontal and Peri-Implant Diseases (EFP 2018).
• Probing pocket depth (PPD) of up to 10 mm.
• Periodontally healthy individuals (no active periodontal disease).
• Implants must have been in function (loaded) for at least one year.
• Age ≥ 18 years.
• Medically healthy individuals or those with well-controlled systemic conditions.
• Implant-supported restorations must be accessible for proper oral hygiene.
• Patients must provide signed informed consent for participation.
• Non-smokers only

Exclusion Criteria:

• Presence of systemic diseases or medications that could influence treatment outcomes (e.g., uncontrolled diabetes, chemotherapy, immunosuppression).
• Underwent peri-implantitis treatment in the past 3 months.
• Use of antibiotics or antimicrobial therapy in the past 3 months.
• Pregnancy or breastfeeding.
• Smokers

The individual participant data (IPD) collected during this study, including clinical data (e.g., probing pocket depth, bleeding on probing), microbiological data (e.g., counts of P. gingivalis and F. alocis), and metabolomics data, will be made available to other researchers after the study's completion. This data will be shared for the purpose of further analysis, with a focus on advancing research in peri-implantitis and dental treatments.

The individual participant data, along with the supporting information, will become available after the publication of the final results of this study. The exact timeline for availability and duration of access has not yet been decided.

The access criteria for the individual participant data (IPD) and supporting information have not yet been decided. Further details regarding the review process, who will have access, and the types of analyses permitted will be determined after the publication of the final study results.

The outcomes assessor evaluating clinical and microbiological parameters will be blinded to the treatment allocation to minimize bias.