An interventional study of Conventional Twin Block Appliance in Skeletal Class II Malocclusion and Mandibular Retrognathia, sponsored by Al-Azhar University. Completed at 1 site in Egypt. Open to male participants aged 11 Years to 15 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-07-07.
Sponsored by Al-Azhar University · Not applicable, Interventional, and Treatment
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.
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.
26 studies on the registry are indexed under Micrognathism; 7 are open to participants now.
This study's enrollment of 20 is below the median of 24 across 22 interventional studies indexed under Micrognathism.
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Exclusion Criteria:
Patients treated with a fixed (bonded) Twin Block appliance for correction of skeletal Class II malocclusion due to mandibular retrognathia.
Device: Conventional Twin Block Appliance
Patients treated with a conventional (removable) twin block appliance for correction of skeletal class II malocclusion due to mandibular retrognathia
Device: Conventional Twin Block Appliance
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
Change in Sagittal Skeletal Relationship (ANB Angle)
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.
Time frame: Measured at baseline (pre-treatment) and at the end of active treatment (approximately 12-18 months, based on actual treatment duration)
Change in Sagittal Skeletal Relationship (ANB Angle)
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.
Time frame: Measured at baseline (pre-treatment) and at the end of active treatment (approximately 12-18 months, based on actual treatment duration)
Change in Condylar Position and TMJ Disc Space
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.
Time frame: Measured at baseline (pre-treatment) and at the end of active treatment (approximately 12-18 months, based on actual treatment duration)
Plan to share: No
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Ran from Nov 2023 to primary completion in Dec 2025, 25 months.
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This study is completed, as verified in Jun 2026. You cannot join it, but the record below documents what was studied.
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