Fixed Versus Conventional Twin Block Appliances for Skeletal Class II Malocclusion

NCT07687927 — Not applicable, Completed, 20 participants, Al-Azhar University

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

Registry	NCT07687927
Status	Completed
Phase	Not applicable
Study type	Interventional; non randomized, parallel, masking: none, treatment
Enrollment	20 (Actual)
Sponsor	Al-Azhar University (Other)
Conditions	Skeletal Class II Malocclusion, Mandibular Retrognathia
Interventions	Conventional Twin Block Appliance (Device)
Dates	start 2023-11-08, primary completion 2025-12-23, completion 2025-12-24, first posted 2026-07-07, last updated 2026-07-07
Locations	1 site in Egypt

-Summary

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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+Detailed description

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.

+Arms and interventions

Arm	Type	Interventions	Description
Fixed twin block group	Experimental	Device: Conventional Twin Block Appliance	Patients treated with a fixed (bonded) Twin Block appliance for correction of skeletal Class II malocclusion due to mandibular retrognathia.
Conventional Twin Block Group	Active comparator	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

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

+Outcome measures

Primary outcomes

Change in Sagittal Skeletal Relationship (ANB Angle) [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

Change in Sagittal Skeletal Relationship (ANB Angle) [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.
Change in Condylar Position and TMJ Disc Space [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.

+Eligibility

Sex: Male, ages: 11 Years to 15 Years, accepts healthy volunteers

Inclusion Criteria:

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

Exclusion Criteria:

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

+Locations (1)

Facility	City	Country	Status
Faculty of Dental Medicine, Al-Azhar University	Cairo, Cairo Governorate	Egypt