Surgery-First Orthognathic Surgery in Skeletal Class III Treatment

Surgery First Orthognathic Surgery in Skeletal Class III Treatment: A Study on Digital Dental Models and Computed Tomography Changes

This study evaluates the efficacy and stability of the "Surgery-First" approach (SF approach) in treating patients with skeletal Class III malocclusion, utilizing a combined retrospective and prospective data collection method. Unlike the conventional method, the SF approach performs orthognathic surgery first to correct the skeletal discrepancy, followed by orthodontic treatment. The study aims to analyze pre-operative dentoskeletal characteristics, arch morphology, and treatment complexity indices, as well as assess the hard and soft tissue changes at 1 week and 1 year post-surgery using digital dental models and Computed Tomography (CT) scans.

This is a single-arm interventional study designed to evaluate the efficacy and stability of the Surgery-First approach in patients with skeletal Class III malocclusion. The study utilizes a combined retrospective and prospective data collection method.

The study protocol was approved by the Institutional Ethics Committee in October 2022. The study population includes patients diagnosed with skeletal Class III malocclusion who underwent the Surgery-First orthognathic surgery between June 2019 and March 2025.

Study Procedures:

Baseline Assessment (T0): Pre-operative evaluation includes clinical examination, digital dental model analysis (to assess occlusal characteristics, arch morphology, and treatment need/complexity indices such as ICON and IOFTN), and Computed Tomography (CT) scanning to measure hard and soft tissue characteristics.

Surgical Intervention: All patients underwent the surgery-first orthognathic approach without pre-surgical orthodontic preparation. A CT scan was performed 1 week post-surgery (T1) to evaluate the immediate surgical results.

Follow-up (T2): Post-operative assessment and CT scanning are conducted 12 months post-surgery (T2) to evaluate skeletal stability and soft tissue adaptation.

Data Analysis:

The analysis focuses on the pre-surgical dentoskeletal characteristics and treatment need indices at baseline, as well as the displacement of the maxilla/mandible and soft tissue changes between time points (T0, T1, and T2).

Inclusion Criteria:

• Female patients aged 16 years or older, and male patients aged 18 years or older.
• Diagnosis of skeletal Class III malocclusion.
• Meeting the clinical indications for the Surgery-First orthognathic approach.
• Treatment plan consensus between the orthodontist and maxillofacial surgeon, aligned with the patient's chief complaint and expectations.
• Underwent orthognathic surgery using the Surgery-First approach without pre-surgical orthodontic treatment.
• Good general health, fit for general anesthesia.
• Voluntarily agreed to participate in the study and provided informed consent.

Exclusion Criteria:

• Dentofacial deformities secondary to maxillofacial trauma (e.g., midface retrusion due to Le Fort fractures, or mandibular retrusion due to bilateral condylar fractures).
• Presence of systemic diseases or conditions that contraindicate general anesthesia or orthognathic surgery.
• Presence of psychiatric disorders that may compromise treatment cooperation or the informed consent process.