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NCT Number: NCT07687927

Fixed Versus Conventional Twin Block Appliances for Skeletal Class II Malocclusion

This study compares two types of dental appliances a fixed Twin Block appliance and a conventional (removable) Twin Block appliance used to treat a bite problem called skeletal Class II malocclusion in growing children and teenagers. In this condition, the lower jaw is positioned further back than the upper jaw. Both appliance types work by guiding the lower jaw forward during growth. The study uses 3D imaging (cone beam computed tomography, or CBCT) before and after treatment to measure how each appliance affects the bones of the jaw, the teeth, the soft tissue profile of the face, and the jaw joint (temporomandibular joint). The goal is to determine whether the fixed or the conventional version of the appliance produces better treatment outcomes.

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Key information

Conditions

Skeletal Class II Malocclusion Congenital Abnormalities Congenital, Hereditary, and Neonatal Diseases and Abnormalities Craniofacial Abnormalities Jaw Abnormalities Jaw Diseases Malocclusion Malocclusion, Angle Class II Mandibular Retrognathia Maxillofacial Abnormalities Micrognathism Musculoskeletal Abnormalities Musculoskeletal Diseases Overbite Stomatognathic Diseases Stomatognathic System Abnormalities Tooth Diseases

Age range

11 year–15 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

Faculty of Dental Medicine, Al-Azhar University

Cairo, Cairo Governorate, 11765, Egypt

About this study

This comparative clinical study evaluates the skeletal, dentoalveolar, soft-tissue, and condylar/temporomandibular joint (TMJ) effects of fixed versus conventional Twin Block appliances in growing patients diagnosed with skeletal Class II malocclusion due to mandibular retrognathia. Participants were allocated to receive treatment with either a fixed or a conventional (removable) Twin Block appliance. Pre-treatment and post-treatment cone beam computed tomography (CBCT) scans were obtained to assess sagittal jaw relationships, mandibular advancement, dentoalveolar changes (including overjet and overbite correction), soft-tissue profile changes, and condylar position/remodeling within the glenoid fossa, including TMJ disc space measurements. Outcomes between the two appliance groups were compared to evaluate differences in skeletal and dental effects, as well as any differences in condylar/TMJ adaptation associated with each appliance design.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Growing male patients (as judged from clinical examination and confirmed later by (CVM)
  • Skeletal class II with retrognathic mandible.
  • Healthy compliant and motivated patient.
  • No Previous orthodontic treatment.
  • No Severe facial asymmetry determined by clinical or radiographic examination.
  • No Systemic diseases that may affect the treatment results.
  • No tmj disorders.

Exclusion criteria

  • Previous orthodontic treatment.
  • Poor oral hygiene.
  • Severe facial asymmetry determined by clinical or radiographic examination.
  • Systemic disease that may affect the treatment results. 5. TMJ disorders.

Treatment and study plan

Conventional Twin Block Appliance

Device

A removable functional appliance consisting of upper and lower acrylic occlusal bite blocks used to advance the mandible and correct skeletal class II malocclusion in growing patients

Primary outcomes

  1. Change in Sagittal Skeletal Relationship (ANB Angle)

    Time frame: Measured at baseline (pre-treatment) and at the end of active treatment (approximately 12-18 months, based on actual treatment duration)

    Measured using cone beam computed tomography (CBCT), the ANB angle reflects the anteroposterior relationship between the maxilla and mandible. Pre-treatment and post-treatment values will be compared between the fixed and conventional Twin Block appliance groups to assess skeletal correction of Class II malocclusion.

Secondary outcomes

  1. Change in Sagittal Skeletal Relationship (ANB Angle)

    Time frame: Measured at baseline (pre-treatment) and at the end of active treatment (approximately 12-18 months, based on actual treatment duration)

    Measured using cone beam computed tomography (CBCT), the ANB angle reflects the anteroposterior relationship between the maxilla and mandible. Pre-treatment and post-treatment values will be compared between the fixed and conventional Twin Block appliance groups to assess skeletal correction of Class II malocclusion.

  2. Change in Condylar Position and TMJ Disc Space

    Time frame: Measured at baseline (pre-treatment) and at the end of active treatment (approximately 12-18 months, based on actual treatment duration)

    Measured using cone beam computed tomography (CBCT), condylar position within the glenoid fossa will be assessed by evaluating anterior, superior, and posterior joint spaces. TMJ disc space measurements will also be recorded to evaluate condylar remodeling and adaptation. Pre-treatment and post-treatment values will be compared between the fixed and conventional Twin Block appliance groups.

Sponsors and collaborators

Lead sponsor

Al-Azhar University

Other

Registry information

Official study title

Dentoskeletal and Condylar Evaluation of Skeletal Class II Malocclusion by Fixed Twinblock Appliance Versus Conventional Twin Block Appliance Cone Beam Computed Tomography Study

Important dates

Study start
2023
Primary completion
2025
Study completion
2025
First posted
Jul 7, 2026
Registry last updated
Jul 7, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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