Efficacy of RME and Protraction in Skeletal Class III Malocclusion

Not Applicable

Completed

• Conditions: Skeletal Class III Malocclusion

• Registration Number: NCT07053683
• Lead Sponsor: Wuhan Integrated Traditional Chinese and Western Medicine Hospital

Brief Summary

This study aimed to evaluate the impact of rapid maxillary expansion combined with anterior traction on vertical and angular measurements as well as on patient-reported oral health-related quality of life (OHRQoL) in patients with skeletal Class III malocclusion, thereby comprehensively assessing the intervention's effectiveness by integrating both objective clinical metrics and subjective patient-centered outcomes.

Detailed Description

Skeletal Class III malocclusion, characterized by a discrepancy between the maxilla and mandible, is a common condition, particularly in Asian populations. It affects aesthetics, function, and psychological well-being. Early intervention is crucial. Maxillary protraction is an effective treatment, and its efficacy is thought to be enhanced by preceding it with rapid maxillary expansion (RME), which can release circum-maxillary sutures. While this combined approach is clinically utilized, its specific effects on vertical skeletal dimensions and patient-centered outcomes like Oral Health-Related Quality of Life (OHRQoL) are not well-documented. This study was a prospective, randomized controlled trial designed to address this gap. A total of 98 patients with skeletal Class III malocclusion were randomized to receive either combined RME and protraction therapy (experimental group) or protraction therapy alone (control group). The study hypothesized that the combined therapy would lead to superior improvements in vertical linear and angular cephalometric parameters and a greater enhancement in OHRQoL compared to protraction alone over a 6-month period.

Study Timeline

• Study Start: 2021-01-01
• Primary Completion: 2023-07-31
• Study Completion: 2023-07-31
• Status Verified: 2025-06
• Study First Submitted: 2025-06-27
• Study First Submitted QC: 2025-06-27
• Last Update Submitted: 2025-06-27
• Study First Posted: 2025-07-08
• Last Update Posted: 2025-07-08

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 98

Inclusion Criteria

• Clinically diagnosed with skeletal Class III malocclusion, with ANB angle less than 0°, anterior crossbite and reverse overjet, and the mandible cannot be retruded to an edge-to-edge incisor relationship.
• In the late mixed dentition or early permanent dentition stage, concave facial profile, with anterior crossbite or edge-to-edge bite.
• Class III molar relationship according to Angle's classification.
• No significant transverse discrepancies, but may have compensatory upper incisor proclination and lower incisor retroclination.
• Mandible retrudable but cannot achieve edge-to-edge incisor contact.
• No history of orthodontic treatment and no craniofacial developmental abnormalities.

Exclusion Criteria

• History of orthodontic treatment.
• Presence of systemic diseases.
• Other craniofacial anomalies, such as cleft lip and palate.
• Severe organ dysfunction.
• Other dental diseases.
• Voluntary withdrawal from the study.
• History of trauma to the area.

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Primary Outcome Measures

Name	Time	Method
Change in Key Vertical Linear Measurements	Baseline (T0) and 6-month follow-up (T1).	Change in key cephalometric vertical linear parameters, specifically X-A distance (vertical position of the maxilla), PP-Ms distance (vertical position of the maxillary first molar), and MP-Ii distance (vertical position of the mandibular incisor). Measurements are made in millimeters (mm) from lateral cephalometric radiographs and verified with Cone-Beam Computed Tomography (CBCT). An increase in these values indicates vertical skeletal and dental changes.
Change in Key Skeletal Angular Measurements	Baseline (T0) and 6-month follow-up (T1).	Change in key cephalometric angular parameters that define jaw relationships, specifically SNA angle (maxillary position), ANB angle (maxillo-mandibular relationship), and SN-MP angle (mandibular plane angle/vertical dimension). Measurements are made in degrees (°) from lateral cephalometric radiographs and verified with CBCT.
Change in Oral Health-Related Quality of Life (OHRQoL) Score	Baseline (T0) and 6-month follow-up (T1).	Assessed using a validated questionnaire. The total score ranges from 0 to 56. A lower score indicates a greater improvement in quality of life by reflecting a lesser negative impact of oral health on physical, psychological, and social well-being.

Secondary Outcome Measures

Name	Time	Method
Change in Dental Positional Measurements	Baseline (T0) and 6-month follow-up (T1).	Change in cephalometric measurements assessing the position and inclination of the incisors, including the UI-NA angle, UI-LI angle (upper to lower incisor angle), UI-NA distance (upper incisor protrusion), and LI-NB distance (lower incisor position). These are measured in degrees or millimeters as appropriate.

Trial Locations

Locations (1)

Wuhan No.1 Hospital; 🇨🇳 Wuhan, Hubei, China