Comparative Effect of Clear Aligner Mandibular Advancement and Twin Block Appliances in Class II Malocclusion

The goal of this retrospective observational study is to compare the effects of Clear Aligner Mandibular Advancement (MA) and Twin Block (TB) appliances in treating Class II malocclusion, a condition where the lower jaw is underdeveloped. The main questions it aims to answer are:

1. Does mandibular advancement with clear aligners improve jaw and dental alignment as effectively as Twin Block appliances?
2. What are the differences in soft tissue changes, such as chin advancement and lip position, between these two treatments?

Researchers will compare MA and TB appliances to an untreated control group to evaluate their impact on skeletal, dental, and soft tissue outcomes. Participants in the study underwent cephalometric analysis (X-ray measurements) both before and after treatment to assess changes in jaw positioning, overbite, and overjet. The study focuses on how each treatment affects facial aesthetics and dental function.

Participants in the study will:

• Undergo treatment with either clear aligner mandibular advancement or Twin Block appliances.
• Attend follow-up appointments to monitor progress and assess treatment outcomes.

Study Overview

• Status: Completed
• Conditions: CLASS II DIVISION 1 MALOCCLUSION
• Intervention / Treatment: Device: Clear aligner with mandibular function; Device: Twin block

Detailed Description

Supplementary information for Study Design It was a retrospective study that collected patients' routine treatment X-rays (before and after treatment) to measure some angular and linear parameters from the X-rays.

• Study Type: Observational
• Enrollment (Actual): 47

Contacts and Locations

Study Locations

• China
  • Sichuan
    • Chengdu, Sichuan, China, 610041
      • West China School of Stomatology, Sichuan University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The study population consists of patients from the Orthodontics Department at West China Hospital of Stomatology, Sichuan University. This population includes individuals diagnosed with Class II malocclusion who are undergoing or have completed treatment with Mandibular Advancement (MA) or Twin Block (TB) appliances. Eligible participants for the treatment group are those in the mixed dentition or early permanent dentition stages, showing specific cephalometric characteristics such as an ANB angle greater than 4 degrees and an SNB angle less than or equal to 78 degrees.

Description

Inclusion Criteria:

• Patients who have completed MA or TB treatment at the West China Hospital of Stomatology Orthodontic Department.
• Pretreatment lateral cephalometric radiographs showing cervical vertebral maturation stage (CVSM) II or III.
• Patients in the mixed dentition or early permanent dentition stages.
• Class II Division 1 malocclusion according to Angle's classification
• ANB angle > 4°; SNB ≤ 78°.
• Comprehensive medical records and necessary data available pre- and post-treatment.

Exclusion Criteria:

• Missing teeth, supernumerary teeth, or severe dental malformations affecting function.
• Poor oral hygiene.
• Systemic diseases or congenital deformities.
• History of dental or maxillofacial trauma.
• Incomplete or missing records.

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
MA group; Patients receiving routine care for Class II malocclusion, which may include the use of Clear Aligner with Mandibular Advancement (MA) function appliances	Device: Clear aligner with mandibular function; The MA group underwent stepwise mandibular forward movement with clear aligners (Invisalign, Align Inc, CA, USA) worn for 22 hours/day and replaced every 7 days.
TB group; Patients receiving routine care for Class II malocclusion, which may include the use of Twin Block (TB) appliances	Device: Twin block; The TB group used a single appliance continuously, with appropriate reduction of occlusal surface height by 1 mm when clinically indicated. Both groups had follow-up appointments every 6 weeks.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in Skeletal Measurements ( SNB angle)	This study assesses skeletal changes in patients treated for Class II malocclusion with Twin Block (TB) or Mandibular Advancement (MA) appliances at West China School of Stomatology, Sichuan University. The evaluation focuses on the measurement of the SNB angle, a critical skeletal parameter, using cephalometric radiographs. These radiographs are taken as a routine part of the treatment to capture skeletal positioning before the treatment starts and after the treatment concludes. This allows for an analysis of the angular changes due to the orthodontic intervention, providing insights into the effectiveness of the appliances in correcting malocclusions.	Baseline and post-treatment cephalometric radiographs will be taken 1-2 weeks pre and 1-2 weeks post the 12-month treatment at West China School of Stomatology, Sichuan University.
Changes in Soft Tissue Measurements ( soft tissue chin thickness)	This study assesses skeletal changes in patients treated for Class II malocclusion with Twin Block (TB) or Mandibular Advancement (MA) appliances at West China School of Stomatology, Sichuan University. The evaluation focuses on the measurement of the soft tissue chin thickness, using cephalometric radiographs. These radiographs are taken as a routine part of the treatment to capture skeletal positioning before the treatment starts (baseline) and after the treatment concludes (1-2 weeks post the 12-month treatment). This allows for an analysis of the angular changes due to the orthodontic intervention, providing insights into the effectiveness of the appliances in correcting malocclusions.	Baseline and post-treatment cephalometric radiographs will be taken 1-2 weeks pre and 1-2 weeks post the 12-month treatment at West China School of Stomatology, Sichuan University.
Changes in Skeletal Measurements (ANB angle)	This study assesses skeletal changes in patients treated for Class II malocclusion with Twin Block (TB) or Mandibular Advancement (MA) appliances at West China School of Stomatology, Sichuan University. The evaluation focuses on the measurement of the ANB angle, a critical skeletal parameter, using cephalometric radiographs. These radiographs are taken as a routine part of the treatment to capture skeletal positioning before the treatment starts and after the treatment concludes. This allows for an analysis of the angular changes due to the orthodontic intervention, providing insights into the effectiveness of the appliances in correcting malocclusions.	Baseline and post-treatment cephalometric radiographs will be taken 1-2 weeks pre and 1-2 weeks post the 12-month treatment at West China School of Stomatology, Sichuan University.
Changes in Skeletal Measurements ( mandibular length)	This study assesses skeletal changes in patients treated for Class II malocclusion with Twin Block (TB) or Mandibular Advancement (MA) appliances at West China School of Stomatology, Sichuan University. The evaluation focuses on the measurement of the mandibular length (mm), a critical skeletal parameter, using cephalometric radiographs. These radiographs are taken as a routine part of the treatment to capture skeletal positioning before the treatment starts and after the treatment concludes. This allows for an analysis of the angular changes due to the orthodontic intervention, providing insights into the effectiveness of the appliances in correcting malocclusions.	Baseline and post-treatment cephalometric radiographs will be taken 1-2 weeks pre and 1-2 weeks post the 12-month treatment at West China School of Stomatology, Sichuan University

Collaborators and Investigators

• Sponsor: Sichuan University

Publications and helpful links

General Publications

• Alsaggaf DH, Afify AR, Zawawi KH, Alsulaimani FF. Factors influencing the orthodontic treatment plan in Class II malocclusion. Am J Orthod Dentofacial Orthop. 2022 Jun;161(6):829-837.e1. doi: 10.1016/j.ajodo.2021.01.034. Epub 2022 Jan 29.

Study record dates

Study Major Dates

• Study Start (Actual): August 1, 2021
• Primary Completion (Actual): August 1, 2022
• Study Completion (Actual): June 30, 2024

Study Registration Dates

• First Submitted: September 16, 2024
• First Submitted That Met QC Criteria: September 21, 2024
• First Posted (Actual): September 24, 2024

Study Record Updates

• Last Update Posted (Actual): September 24, 2024
• Last Update Submitted That Met QC Criteria: September 21, 2024
• Last Verified: September 1, 2024

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Stomatognathic Diseases; Tooth Diseases; Malocclusion; Malocclusion, Angle Class II; Overbite
• Other Study ID Numbers: WCHS-IRB-CT-2023-195

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: confidential

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No