Adjunctive use of Er,Cr:YSGG (erbium-chromium-yttrium-scandium-gallium-garnet) laser in combination with conventional, mechanical periodontal treatment may benefit in complete decontamination of the periodontal pocket leading to improved early healing and better long term clinical result. Radial firing periodontal tip (RFPT) offered by the Er,Cr:YSGG system is devised to let irradiation primarily in radial pattern (85%) with lesser portion in straight manner (15%), meaning laser beams are effectively emitted to affected root surface and inner epithelium of periodontal pocket with simple tip management. Therefore, using Er,Cr:YSGG laser with RFPT could be the best option for periodontal laser therapy. The aim of this study is to investigate adjunctive treatment effect using Er,Cr:YSGG laser and RFPT in moderate to severe periodontitis patients. Study subjects are randomly allocated to either 'scaling and root planing (SRP) only' or 'SRP + laser therapy' group. Periodontal parameters including probing pocket depth (PPD), clinical attachment level (CAL), modified gingival index (MGI), and plaque index (PI) are recorded at baseline and 8 weeks after treatment. Gingival crevicular fluid (GCF) samples are obtained using paper strips at baseline, 1w, 2w, 4w, and 8w post op. to determine laser-induced effect in early wound healing. Cytokine levels are evaluated from the GCF samples taken.

Inclusion Criteria:

1. diagnosis of stage III or IV periodontitis based on the 2017 periodontitis classification (Tonetti, Greenwell, & Kornman, 2018);
2. minimum of two teeth with probing depth (PD) ≥ 6 mm and radiographic bone loss in at least two quadrants of the whole dentition;
3. each quadrant with a minimum of four teeth; and
4. systemically healthy patients.

Exclusion Criteria:

1. history of periodontal treatment in the previous six months;
2. antibiotic medication in recent three months;
3. under steroid therapy or taking any anti-inflammatory drugs in recent three months;
4. history of any systemic disease that may influence the periodontal condition and treatment outcome, including diabetes mellitus, cancer, metabolic diseases, cardiovascular disease, and rheumatoid arthritis;
5. pregnancy or breastfeeding; and
6. smoking habits.