Modified Versus Clear Twin Block for Skeletal Class II Malocclusion

NCT07608406 | Active Not Recruiting

• 2 other identifiers: MClearTBUADS-3478-26052024/SRC-1994
• Study Type: interventional
• Target: 40
• Locations: 1 country
• Sites: 1

Brief Summary

This study aims to evaluate the effectiveness of a modified Twin Block appliance compared to a conventional clear Twin Block appliance in the treatment of skeletal Class II malocclusion caused by mandibular retrusion in growing patients. This is a two-arm randomized controlled clinical trial including patients aged 10-13 years diagnosed with skeletal Class II malocclusion. Participants will be randomly allocated into two equal groups. Skeletal, dental, and soft tissue changes will be assessed using lateral cephalometric analysis and cone-beam computed tomography (CBCT). Additionally, temporomandibular joint (TMJ) health, pain perception, and functional tolerance will be evaluated using standardized clinical indices and patient-reported outcome measures. The study aims to compare the modified appliance with the conventional design in terms of skeletal improvement, TMJ safety, and patient acceptance.

Conditions

Skeletal Class II Malocclusion

Keywords

Twin Block appliance; Class II malocclusion; Mandibular advancement; Functional orthopedic treatment; CBCT

Outcome Measures

Primary Outcomes (4)

• Change in mandibular skeletal position measured by SNB angle on lateral cephalometric radiographs

  Assessment of sagittal mandibular skeletal position using the SNB angle (degrees) measured on standardized lateral cephalometric radiographs.

  Baseline (T0) and after 7 months of treatment (T1)

• Change in effective mandibular length measured by Co-Gn distance on lateral cephalometric radiographs

  Assessment of mandibular length using the Condylion-Gnathion (Co-Gn) linear measurement in millimeters obtained from lateral cephalometric analysis.

  Baseline (T0) and after 7 months of treatment (T1)

• Change in condylar dimensions assessed using cone-beam computed tomography (CBCT)

  Assessment of temporomandibular condylar morphology using CBCT, including condylar length, condylar width, and condylar height measured in millimeters.

  Baseline (T0) and after 7 months of treatment (T1)

• Change in temporomandibular joint spaces assessed using CBCT

  Assessment of condylar position within the glenoid fossa using CBCT measurements of anterior joint space (AJS), superior joint space (SJS), posterior joint space (PJS), and medial joint space (MJS), measured in millimeters.

  Baseline (T0) and after 7 months of treatment (T1)

Secondary Outcomes (8)

• Temporomandibular joint dysfunction symptoms assessed using the Helkimo Anamnestic Index (Ai)

  Baseline (T0) and after 7 months of treatment (T1)

• Patient-reported pain intensity assessed using a Numeric Rating Scale (NRS)

  1 week, 2 weeks, 6 weeks, 3 months, and 6 months after appliance insertion

• Patient-reported discomfort and functional limitation assessed using a validated questionnaire

  1 week, 2 weeks, 6 weeks, 3 months, and 6 months after appliance insertion

• Change in lower incisor inclination measured by IMPA on lateral cephalometric radiographs

  Baseline (T0) and after 7 months of treatment (T1)

• Change in upper incisor inclination measured by U1-SN angle on lateral cephalometric radiographs

  Baseline (T0) and after 7 months of treatment (T1)

Study Arms (2)

Modified Twin Block Group

EXPERIMENTAL

Patients in this group will be treated using a modified Twin Block appliance incorporating progressive mandibular advancement and lower lip pads designed to influence muscular activity and enhance skeletal effects.

Device: Modified Twin Block Appliance

Conventional Clear Twin Block Group

ACTIVE COMPARATOR

Patients in this group will be treated using a conventional clear Twin Block functional appliance for correction of skeletal Class II malocclusion.

Device: Conventional Clear Twin Block Appliance

Interventions

Modified Twin Block Appliance DEVICE

A modified Twin Block functional appliance incorporating progressive mandibular advancement and lower lip pads designed to modify muscular activity and enhance mandibular growth. The appliance is used for the treatment of skeletal Class II malocclusion due to mandibular retrusion in growing patients.

Also known as: Progressive Twin Block

Modified Twin Block Group

Conventional Clear Twin Block Appliance DEVICE

A conventional clear Twin Block functional appliance used for correction of skeletal Class II malocclusion in growing patients. The appliance acts by posturing the mandible forward to stimulate functional and skeletal adaptation.

Also known as: Clear Twin Block

Conventional Clear Twin Block Group

Eligibility Criteria

• Age: 10 Years - 13 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17)

You may qualify if:

• Systemically healthy patients.
• Patients willing to accept removable functional appliance therapy.
• Skeletal Class II malocclusion (Angle Class II Division 1).
• Skeletal Class II due to mandibular retrusion (ANB ≥ 5°, 6 mm ≤ OJ ≤ 13 mm , SNB ≤ 78°, with normal maxillary position).
• Growth stage corresponding to MP3 stage or pre-pubertal peak according to hand-wrist radiograph (Björk and Helm, 1967).
• No severe dental crowding in the dental arches and no significant maxillary dental protrusion.
• Absence of congenital anomalies, trauma, burns, or surgical scars affecting the temporomandibular joint or craniofacial structures.
• Absence of systemic or rheumatologic diseases affecting the temporomandibular joint.

You may not qualify if:

• Presence of clinical signs or symptoms of temporomandibular joint disorders.
• Functional mandibular deviation.
• Previous orthodontic treatment.

Sponsors & Collaborators

• University of Aleppo: lead

Study Sites (1)

Faculty of Dentistry, University of Aleppo

Aleppo, Aleppo Governorate, Syria

Location

Related Publications (9)

• Wu Y, Yu Q, Xia Y, Wang B, Chen S, Gu K, Zhang B, Zhu M. Does mandibular advancement with clear aligners have the same skeletal and dentoalveolar effects as traditional functional appliances? BMC Oral Health. 2023 Feb 2;23(1):65. doi: 10.1186/s12903-023-02709-5.

  PMID: 36732724 RESULT

• Lombardo EC, Lione R, Franchi L, Gaffuri F, Maspero C, Cozza P, Pavoni C. Dentoskeletal effects of clear aligner vs twin block-a short-term study of functional appliances. J Orofac Orthop. 2024 Sep;85(5):317-326. doi: 10.1007/s00056-022-00443-1. Epub 2023 Jan 18.

  PMID: 36651930 RESULT

• Caruso S, Nota A, Caruso S, Severino M, Gatto R, Meuli S, Mattei A, Tecco S. Mandibular advancement with clear aligners in the treatment of skeletal Class II. A retrospective controlled study. Eur J Paediatr Dent. 2021;22(1):26-30. doi: 10.23804/ejpd.2021.22.01.05.

  PMID: 33719479 RESULT

• Tripathi T, Singh N, Rai P, Gupta P. Comparison of Dentoskeletal Changes, Esthetic, and Functional Efficacy of Conventional and Novel Esthetic Twin Block Appliances among Class II Growing Patients: A Pilot Study. Turk J Orthod. 2020 Jun 1;33(2):77-84. doi: 10.5152/TurkJOrthod.2020.19030. eCollection 2020 Jun.

  PMID: 32637187 RESULT

• Golfeshan F, Soltani MK, Zohrei A, Poorolajal J. Comparison between Classic Twin-block and a Modified Clear Twin-block in Class II, Division 1 Malocclusions: A Randomized Clinical Trial. J Contemp Dent Pract. 2018 Dec 1;19(12):1455-1462.

  PMID: 30713173 RESULT

• Gill DS, Lee RT. Prospective clinical trial comparing the effects of conventional Twin-block and mini-block appliances: Part 1. Hard tissue changes. Am J Orthod Dentofacial Orthop. 2005 Apr;127(4):465-72; quiz 517. doi: 10.1016/j.ajodo.2004.11.012.

  PMID: 15821691 RESULT

• Banks P, Wright J, O'Brien K. Incremental versus maximum bite advancement during twin-block therapy: a randomized controlled clinical trial. Am J Orthod Dentofacial Orthop. 2004 Nov;126(5):583-8. doi: 10.1016/j.ajodo.2004.03.024.

  PMID: 15520691 RESULT

• Kyburz KS, Eliades T, Papageorgiou SN. What effect does functional appliance treatment have on the temporomandibular joint? A systematic review with meta-analysis. Prog Orthod. 2019 Aug 12;20(1):32. doi: 10.1186/s40510-019-0286-9.

  PMID: 31402395 RESULT

• Chadwick SM, Banks P, Wright JL. The use of myofunctional appliances in the UK: a survey of British orthodontists. Dent Update. 1998 Sep;25(7):302-8.

  PMID: 10478026 RESULT

MeSH Terms

Conditions

Overbite

Condition Hierarchy (Ancestors)

Malocclusion, Angle Class II; Malocclusion; Tooth Diseases; Stomatognathic Diseases

Study Officials

• Abdulmalek Majanni, PhD

  Faculty of Dentistry, University of Aleppo

  STUDY DIRECTOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Associate Professor

Model Details: Participants will be randomly assigned into two parallel groups receiving either a modified Twin Block appliance or a conventional clear Twin Block appliance.

Study Record Dates

• First Submitted: May 12, 2026
• First Posted: May 27, 2026
• Study Start: May 17, 2026
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): December 1, 2026
• Last Updated: July 14, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will not share

Locations

SY (1)