The goal of this clinical trial is to evaluate the efficacy of adjunctive application of diode laser to mechanical, non-surgical root surface debridement in patients attending periodontal office. The main question it aims to answer is:

To compare the clinical effectiveness of adjunctive application of a 940-nm diode laser with root surface debridement to the effectiveness of root surface debridement alone.

This study is a split-mouth design, where each quadrant will be randomly allocated to one of the following groups:

Control group (root surface debridement - RsD): scaling and root planing alone. Laser group (RsD + laser): scaling and root planing with adjunctive diode laser therapy Quadrants will be randomly allocated to the treatment groups

Inclusion Criteria:

1. Systemically healthy patients
2. Each patient should have more than 20 teeth remaining, and at least 5 teeth per quadrant
3. Each patient presented ≥ 30% of sites involved
4. At least 2 teeth with a probing depth of ≥ 5 mm in each quadrant, with evident radiographic bone loss.

Exclusion Criteria:

1. History of systemic diseases affecting the periodontium
2. Smokers and alcoholic patients
3. Use of medication within the last 6 months, which might affect the periodontal status
4. Pregnant and lactating women
5. Patients who had any periodontal treatment ≤ 12 months before the examination.

no personal data will be shared and/or disclosed. only periodontal parameters collected from the medical registries will be statistically analyzed and further published in the scientific literature