Gingival enlargement is a common complication in orthodontic patients, often resulting from plaque accumulation and chronic inflammatory response during fixed appliance therapy. Surgical gingivectomy is frequently required to restore gingival contour, improve esthetics, and facilitate oral hygiene. Traditionally, gingivectomy is performed using a scalpel, but laser-assisted techniques have recently gained popularity due to their potential benefits, including reduced bleeding, postoperative discomfort, and faster healing.

This randomized split-mouth clinical trial aims to compare the clinical and microbiological outcomes of gingivectomy performed with a diode laser versus conventional scalpel surgery in orthodontic patients presenting with gingival enlargement. Clinical parameters, microbial profiles, and patient-reported outcomes will be evaluated at baseline and at multiple postoperative intervals to assess the effectiveness and advantages of each technique.

Gingival enlargement is a frequent periodontal manifestation in patients undergoing fixed orthodontic treatment, primarily resulting from increased plaque retention and subsequent chronic inflammation. This condition can compromise esthetics, interfere with effective oral hygiene, and lead to periodontal complications if left untreated. Gingivectomy is the treatment of choice for removing excess gingival tissue and reestablishing physiological gingival contours. Conventional scalpel gingivectomy has been widely used; however, the advent of laser technology, particularly diode lasers, has provided an alternative surgical approach with potential clinical advantages, including better hemostasis, reduced intraoperative discomfort, faster wound healing, and less postoperative pain.

This study is designed as a randomized split-mouth clinical trial to compare the clinical and microbiological outcomes of gingivectomy performed using a scalpel versus a diode laser in orthodontic patients with gingival enlargement. Eligible participants will be recruited from the Orthodontics Department of the Ho Chi Minh City National Hospital of Odonto-Stomatology. Each patient will undergo gingivectomy on two contralateral quadrants: one quadrant treated with conventional scalpel surgery (control side) and the other with diode laser surgery (test side). The allocation of quadrants will be randomized.

Clinical parameters including Plaque Index (PlI), Gingival Index (GI), Probing Pocket Depth (PPD), Gingival Margin Position (GMP), and Bleeding on Probing (BoP) will be recorded at baseline and at multiple postoperative intervals. Subgingival plaque samples will be collected for microbiological analysis using real-time polymerase chain reaction (qPCR) to evaluate the presence and levels of periodontopathogenic bacteria. Patient-reported outcomes such as postoperative pain will also be assessed using a visual analog scale (VAS).

All surgical procedures will be performed by the same calibrated operator to minimize variability. Standardized oral hygiene instructions will be provided to all participants throughout the study period. The collected data will be analyzed to determine differences in clinical healing, microbial changes, and patient comfort between the two treatment modalities. The findings are expected to provide evidence-based insights into the advantages and limitations of diode laser gingivectomy compared with the traditional scalpel technique in orthodontic patients.

Inclusion Criteria:

• Participants aged 18 years or older who agree to take part in the study.
• Individuals in good general health with no history of systemic diseases.
• Patients undergoing fixed orthodontic treatment with metallic brackets for at least 6 months and presenting with gingival enlargement.
• Patients with good oral hygiene (Plaque Index [PlI] < 1) and who comply with the instructions provided by the dentist during the treatment period.

Exclusion Criteria:

• History of using medications associated with gingival enlargement, such as anticonvulsants, immunosuppressants, or calcium channel blockers (e.g., phenytoin, cyclosporine, nifedipine, verapamil, diltiazem, felodipine, nitredipine, etc.).
• Pregnant or breastfeeding women, or individuals using hormonal therapy.
• Patients who have undergone periodontal treatment within the last 6 months.
• Use of antibiotics within 3 months prior to study enrollment.
• Presence or history of systemic diseases.
• Patients who refuse the use of laser in treatment.
• Patients who are uncooperative, have poor oral hygiene (PlI > 1), discontinue participation during the study, or fail to follow instructions throughout the study period.

The individual participant data (IPD) will not be shared because the study is conducted as part of a postgraduate thesis with a limited scope and without a formal data sharing agreement.

Due to the nature of the interventions, masking of participants and operators was not feasible. Outcome assessors were blinded to the type of intervention performed at each site.