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.

Study Overview

• Status: Completed
• Conditions: Skeletal Class III Malocclusion
• Intervention / Treatment: Procedure: Surgery-First Orthognathic Surgery

Detailed Description

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).

• Study Type: Interventional
• Enrollment (Actual): 60
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Vietnam
  • Hanoi
    • Hanoi, Hanoi, Vietnam, 10000
      • Hanoi Medical University Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Surgery-First Cohort; Patients diagnosed with skeletal Class III malocclusion who undergo the Surgery-First approach.	Procedure: Surgery-First Orthognathic Surgery; Orthognathic surgery (Le Fort I, BSSO, or double jaw surgery) performed before orthodontic treatment to correct skeletal discrepancy.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Three-Dimensional Skeletal and Soft Tissue Changes on Computed Tomography (CT)	Evaluation of dentoskeletal and facial soft tissue changes. The measurements include the three-dimensional (3D) spatial displacement of hard and soft tissue landmarks, as well as angular and linear cephalometric parameters (e.g., SNA, SNB, ANB angles) measured on Computed Tomography (CT) images. Comparisons are made across three time points to assess immediate surgical changes and long-term stability.	Baseline (T0), 1 week post-surgery (T1), and 12 months post-surgery (T2)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pre-surgical Dental Arch Characteristics and Treatment Need Indices	Assessment of pre-surgical occlusal characteristics and arch morphology using 3D digital dental models. The evaluated parameters include, but are not limited to, overbite, overjet, Arch Length Discrepancy (ALD), Intercanine Width (ICW) and Intermolar Width (IMW) discrepancies, Arch Form Asymmetry Index (AI), Asymmetric Tooth Number (ATN), and the depth of the Curve of Spee. Additionally, the complexity and functional need for treatment are evaluated using standardized indices such as the Index of Complexity, Outcome and Need (ICON) and the Index of Orthognathic Functional Treatment Need (IOFTN).	Baseline (T0)

Collaborators and Investigators

• Sponsor: Hanoi Medical University

Study record dates

Study Major Dates

• Study Start (Actual): March 1, 2022
• Primary Completion (Actual): April 1, 2026
• Study Completion (Actual): May 1, 2026

Study Registration Dates

• First Submitted: February 19, 2026
• First Submitted That Met QC Criteria: February 19, 2026
• First Posted (Actual): February 25, 2026

Study Record Updates

• Last Update Posted (Actual): May 19, 2026
• Last Update Submitted That Met QC Criteria: May 15, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: computed tomography; 3D analysis; surgery first orthognathic approach; digital dental model
• Other Study ID Numbers: 657/GCN-HDDDNCYSH-DHYHN

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: There is no plan to share individual participant data to protect patient privacy and intellectual property before all publications are completed.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No