The purpose of this prospective, randomized, controlled, single-blind clinical trial is to compare the efficacy of local submucosal administration of dexamethasone versus methylprednisolone on postoperative morbidity following impacted lower third molar surgery. The study evaluates postoperative pain using the Visual Analog Scale (VAS) and quantifies three-dimensional facial edema using a mobile smartphone-based scanning workflow (Qlone aligned in CloudCompare). Patients requiring unilateral extraction of fully bone-impacted mandibular third molars are randomly allocated into three parallel groups: Control (no injection), Methylprednisolone (40 mg), and Dexamethasone (8 mg).

Surgical extraction of impacted mandibular third molars routinely induces significant inflammatory sequelae, including pain, edema, and trismus, which substantially impair patient quality of life. Although local submucosal corticosteroid delivery is a well-established adjunctive approach to minimize postoperative discomfort, head-to-head volumetric comparisons using three-dimensional facial analysis workflows remain limited. This clinical trial implements a rigorous parallel design to isolate the anti-inflammatory efficacy of two widely utilized corticosteroids. Following a standardized surgical osteotomy and tooth removal performed by a single experienced surgeon, participants receive either a standardized 2 mL submucosal injection of 40 mg methylprednisolone sodium succinate, 8 mg dexamethasone sodium phosphate, or no injection at the distobuccal aspect of the adjacent second molar. Three-dimensional digital surface models are acquired preoperatively and longitudinally on postoperative days 3 and 7 to evaluate precise volumetric facial changes. Concurrently, subjective patient-reported pain kinetics are systematically dökümante edilmiştir via regular VAS recordings.

Inclusion Criteria:

• 1. Systemically healthy individuals classified as ASA I according to the American Society of Anesthesiologists.

  2. Patients between 18 and 35 years of age. 3. Presence of a unilateral, fully bone-impacted mandibular third molar with an indication for surgical extraction.

  4. Impacted teeth classified as Class II or III and Position B or C according to the Pell-Gregory classification system.

  5. Impacted teeth with mesioangular or vertical angulation based on Winter's classification.

  6. A moderate surgical difficulty level (score of 5 to 7) confirmed via the Pederson difficulty index.

  7. Competency to provide written informed consent and willingness to adhere to follow-up schedules.

Exclusion Criteria:

• 1. Presence of any systemic disease or medical condition that contraindicates the use of systemic or local corticosteroids.

  2. Pregnancy or lactation. 3. Active pericoronitis, acute infection, or pathology (e.g., cysts, tumors) associated with the target third molar or adjacent structures.

  4. Use of antibiotics, systemic corticosteroids, or regular anti-inflammatory medications within the past 30 days prior to surgery.

  5. History of daily tobacco smoking within the past 6 months. 6. Known allergy or hypersensitivity to local anesthetics, dexamethasone, methylprednisolone, or the prescribed postoperative medications (amoxicillin, clavulanic acid, paracetamol, dexketoprofen).

  7. Inability to comply with the 3D facial scanning protocols or postoperative follow-up appointments.

De-identified individual participant data underlying the results reported in the final manuscript (including demographic characteristics, baseline surgical parameters, 3D facial volumetric measurements, and pain VAS scores) will be made available to qualified researchers upon reasonable academic request.

The data will become available immediately following publication of the final manuscript and will remain accessible for up to 3 years.

Data will be accessible to qualified clinical researchers upon submitting a scientifically sound research proposal. Requests should be directed via email to the corresponding author (dt.irfanustundag@gmail.com) and require a signed data use agreement.

Due to the absence of a placebo injection in the control group, complete patient and surgeon blinding could not be achieved. However, a single-blind design was rigorously maintained by completely blinding the clinical outcomes assessor, who performed the digital three-dimensional facial scanning superimpositions and volumetric edema data calculations in CloudCompare software, to the group allocations.