This prospective, randomized, single-blind, assessor-blinded, parallel-group clinical trial aims to compare the effects of 970-nm diode laser and liquid nitrogen cryotherapy in patients requiring maxillary labial frenectomy.

The primary objective is to compare the change in salivary cortisol levels from baseline to postoperative day 2 between the two treatment groups. Secondary objectives include comparison of postoperative pain, edema, interincisal mouth opening, analgesic consumption, operation duration, state anxiety, clinical wound healing, and adverse events.

Eligible adult patients with an indication for maxillary labial frenectomy will be randomly assigned to receive either 970-nm diode laser frenectomy or liquid nitrogen cryotherapy. Salivary cortisol samples and clinical outcomes will be assessed during the early postoperative follow-up period.

Maxillary labial frenulum abnormalities may be associated with diastema, plaque accumulation, periodontal irritation, gingival recession, oral hygiene difficulty, functional discomfort, and esthetic concerns. Frenectomy may be indicated when the frenulum is hypertrophic, short, thick, or inserted close to the interdental papilla.

Conventional scalpel frenectomy is effective but may be associated with intraoperative bleeding, need for suturing, postoperative pain, edema, and reduced patient comfort. Minimally invasive approaches such as diode laser surgery and cryotherapy may offer potential advantages in oral soft tissue procedures.

This study will compare two minimally invasive approaches for maxillary labial frenectomy: 970-nm diode laser and liquid nitrogen cryotherapy. Participants will be randomized into two parallel groups. In the diode laser group, frenectomy will be performed using a 970-nm diode laser at 2 W in continuous wave mode with a 320-micrometer sterile fiber tip using a contact technique. In the liquid nitrogen cryotherapy group, open-spray cryotherapy will be applied to the maxillary labial frenulum region with two freeze-thaw cycles.

The primary endpoint is the change in salivary cortisol level from baseline to postoperative day 2. Secondary endpoints include postoperative day 7 salivary cortisol change, postoperative pain measured by visual analog scale, edema, interincisal mouth opening, total analgesic consumption, operation duration, State-Trait Anxiety Inventory-State score, Landry, Turnbull and Howley wound healing index scores, and postoperative complications or adverse events.

All procedures and salivary sampling will be standardized and performed in the morning to reduce the influence of circadian variation on cortisol measurements. The study will be conducted at the Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Kutahya Health Sciences University.

Inclusion Criteria:

• Age between 18 and 65 years.
• Systemically healthy, ASA I status.
• Clinical indication for maxillary labial frenectomy.
• Ability to attend postoperative follow-up visits.
• Provision of written informed consent.

Exclusion Criteria:

• Systemic or local corticosteroid use within the last 6 months.
• Endocrine disease that may affect cortisol levels.
• Pregnancy or lactation.
• Active oral infection.
• Chronic analgesic or anti-inflammatory drug use.
• Psychiatric medication use.
• Smoking.
• ASA II or higher systemic status.
• Inability to attend follow-up visits.
• Refusal to participate in the study.

Postoperative clinical outcome assessments, including wound healing scoring, will be performed by an outcomes assessor who is blinded to the allocated intervention group.