The goal of this clinical trial is to learn whether using a special light-activated treatment called photodynamic therapy, or more specifically, its modified version called oxygen high-level laser therapy, using a high-powered diode laser along with 3% hydrogen peroxide, can improve gum health around dental implants. It tests whether adding this to regular cleaning treatments could reduce harmful bacteria and support better healing. The aim is to determine whether a specific protocol is an effective way to treat infections around dental implants.

Participants in the study will receive two types of treatment on different dental implants:

• One implant will be treated with the oxygen high-level laser therapy using diode laser and hydrogen peroxide after mechanical cleaning.
• The other implant will receive diode laser therapy without hydrogen peroxide after mechanical cleaning.

Researchers will compare how the gums respond to each treatment, looking at signs such as inflammation, and determine whether the number of harmful bacteria has been reduced at three time points.

Participants attending with at least two non-adjacent dental implants diagnosed with peri-implant disease (peri-implant mucositis and peri-implantitis) will be enrolled in the study. All patients included will be examined, and periodontal chartings will be obtained using a PCPUNC 15 probe. After routine phase one therapy (mechanical debridement using carbon-coated curettes on dental implants and ultrasonic scaling on the rest of the dentition), implant pocket irrigation using normal saline will be performed in both groups. Following irrigation using normal saline, implant pockets will be irrigated with 3% hydrogen peroxide, left in place for 2 minutes, and then irradiated with a 940nm diode laser (2.5W power, high frequency, 10 KHz, power average 0.5 W, fluency 25,000 J/cm2, 416.66 J/cm2 per second [Rey Protocol]) for 60 s per site in the test group. Control groups will receive mechanical debridement and diode laser treatment alone without the use of hydrogen peroxide.

Baseline clinical parameters will be measured at the initial visit and compared to post-treatment results at 6 weeks and 3 months. The clinical parameters to be evaluated include probing pocket depth, gingival index, plaque index, bleeding on probing, and suppuration.

In addition, microbiological parameters (bacterial count) using quantitative real-time polymerase chain reaction (qPCR) analysis will be determined from subgingival plaque samples using sterile paper points before and after treatment of both groups left in place for 30 seconds. Supragingival plaque is to be removed, and microbiological samples are to be taken before any measurements and/or non-surgical periodontal therapy (NSPT) from the deepest peri-implant pockets (sites are to be isolated with cotton rolls and gently air dried to avoid contamination with saliva). Immediately following treatment, a second swab will be taken from the implant surface using the same procedure discussed previously. Further samples will be collected at 6 week and 3-month follow-ups and processed.

Inclusion Criteria:

• Patients 18 years or older.
• Patients diagnosed with peri-implant disease (peri-implant mucositis or peri-implantitis) according to the 2017 World Workshop criteria in at least two non-adjacent, single-crown, bone-level dental implants.
• Patients that have not undergone periodontal treatment and/or were prescribed antibiotics in the last three months prior to initial visit.
• Patients with a healthy periodontal status
• At least 1 year of functional implants.
• Non-Smokers.

Exclusion Criteria:

• Immunocompromised patients.
• Pregnancy or breastfeeding.
• Known allergies to any materials used in the study.
• Patients classified as ASA Physical Status ≥ III.

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