An interventional study of Myobrace Interceptive Class III Appliance and Frankel III Functional Regulator in Cross Bite, sponsored by Sana'a University. Active, not recruiting at 1 site in Yemen. Open to participants aged 6 Years to 10 Years. Per ClinicalTrials.gov, last updated 2026-09-24.
Sponsored by Sana'a University · Not applicable, Interventional, and Treatment
This randomized controlled clinical trial will evaluate the effectiveness of the Myobrace appliance in correcting anterior and posterior crossbite in children aged 6 to 10 years during the mixed dentition stage. The study will compare the clinical effects of Myobrace with those of the Frankel III appliance. The study will assess changes in occlusion, skeletal and dentoalveolar relationships, and soft tissue characteristics before and after treatment. The study will also evaluate the effectiveness of the two treatment approaches in improving crossbite correction and related orthodontic outcomes.
Crossbite is a common malocclusion in children and may involve anterior or posterior teeth. Early management during the mixed dentition stage may help improve the occlusal relationship and reduce the potential for progression of the malocclusion.
This randomized controlled clinical trial is designed to evaluate the effectiveness of the Myobrace appliance for the correction of crossbite in children aged 6 to 10 years during the mixed dentition stage. The study will compare treatment with the Myobrace appliance with treatment using the Frankel III appliance.
Eligible children with anterior and/or posterior crossbite will be allocated to one of the treatment groups according to the study randomization protocol. Participants will receive the assigned appliance and will be followed throughout the treatment period according to the study protocol.
Treatment effectiveness will be evaluated by comparing clinical and orthodontic measurements obtained before and after treatment. The assessment will include correction of the crossbite and changes in skeletal, dentoalveolar, and soft tissue relationships. Cephalometric analysis will be used to assess relevant skeletal, dentoalveolar, and soft tissue changes.
The study will provide clinical information regarding the effectiveness of Myobrace treatment for crossbite correction during the mixed dentition stage and will allow comparison of its treatment effects with those of the Frankel III appliance.
323 studies on the registry are indexed under Malocclusion; 85 are open to participants now.
This study's enrollment of 40 is close to the median of 37 across 242 interventional studies indexed under Malocclusion.
Browse Malocclusion studies →Sana'a University is the lead sponsor of 27 studies on the registry; 15 are open to participants now.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants assigned to this arm will receive the Myobrace® Interceptive Class III appliance during the mixed dentition stage. Participants will be instructed to wear the appliance for approximately 1-2 hours during the day and overnight, together with daily myofunctional exercises and instructions regarding nasal breathing, tongue posture, swallowing, and lip competence. Treatment will continue until crossbite correction is achieved or for a maximum of 18 months, whichever occurs first.
Device: Myobrace Interceptive Class III Appliance
Participants assigned to this arm will receive the Frankel III (FR-III) functional regulator during the mixed dentition stage. The appliance will be used according to the clinical treatment protocol. Treatment will continue until crossbite correction is achieved or for a maximum of 18 months, whichever occurs first. Clinical and cephalometric assessments will be performed before and after treatment to evaluate changes in skeletal, dentoalveolar, and occlusal relationships.
Device: Frankel III Functional Regulator
Participants will receive the Myobrace® Interceptive Class III appliance during the mixed dentition stage. The appliance will be used according to the study treatment protocol, with instructions for approximately 1-2 hours of daytime wear and overnight wear, together with daily myofunctional exercises and instructions regarding nasal breathing, tongue posture, swallowing, and lip competence. Treatment will continue until crossbite correction is achieved or for a maximum of 18 months, whichever occurs first.
Participants will receive the Frankel III (FR-III) functional regulator during the mixed dentition stage. The appliance will be used according to the study treatment protocol. Treatment will continue until crossbite correction is achieved or for a maximum of 18 months, whichever occurs first. Clinical and cephalometric assessments will be performed before and after treatment to evaluate changes in skeletal, dentoalveolar, and occlusal relationships.
Also known as: FR-III
Change in Crossbite Correction Status
Change in occlusal crossbite status from baseline to treatment completion, assessed clinically by the presence or absence of anterior and/or posterior crossbite. Complete correction is defined as establishment of a normal anterior and/or posterior buccolingual occlusal relationship according to the type of crossbite present at baseline. The change will be assessed for each participant by comparing the post-treatment crossbite status with the participant's baseline status. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months
Change in Overjet
Change from baseline in overjet, measured in millimeters (mm) as the horizontal distance between the maxillary and mandibular incisors. The change will be calculated for each participant by comparing the post-treatment overjet value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in Overbite
Change from baseline in overbite, measured in millimeters (mm) as the vertical overlap between the maxillary and mandibular incisors. The change will be calculated for each participant by comparing the post-treatment overbite value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Anterior Crossbite Correction
Correction of anterior crossbite at treatment completion, assessed for each participant by comparing the post-treatment anterior crossbite status with the participant's baseline status. Correction is defined as establishment of a positive or normal horizontal overlap between the maxillary and mandibular anterior teeth that were in crossbite at baseline. The proportion of participants achieving anterior crossbite correction will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Posterior Crossbite Correction
Correction of posterior crossbite at treatment completion, assessed for each participant by comparing the post-treatment posterior crossbite status with the participant's baseline status. Correction is defined as establishment of a normal transverse buccolingual relationship between the maxillary and mandibular posterior teeth that were in crossbite at baseline. The proportion of participants achieving posterior crossbite correction will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in ANB
Change from baseline in the ANB angle, measured in degrees (°) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment ANB value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in SNA
Change from baseline in the SNA angle, measured in degrees (°) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment SNA value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in SNB
Change from baseline in the SNB angle, measured in degrees (°) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment SNB value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in Wits Appraisal
Change from baseline in Wits appraisal, measured in millimeters (mm) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment Wits appraisal value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in SN-MP
Change from baseline in the SN-MP angle, measured in degrees (°) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment SN-MP value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in SN-OP
Change from baseline in the SN-OP angle, measured in degrees (°) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment SN-OP value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in Ar-Go-Me (Gonial Angle)
Change from baseline in the Ar-Go-Me (gonial) angle, measured in degrees (°) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment Ar-Go-Me value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in Y-axis (Por-Gns)
Change from baseline in the Y-axis (Por-Gns) angle, measured in degrees (°) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment Y-axis value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in FMA
Change from baseline in the FMA (Frankfort-Mandibular Plane Angle), measured in degrees (°) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment FMA value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in IMPA
Change from baseline in the IMPA (Incisor to Mandibular Plane Angle), measured in degrees (°) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment IMPA value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in FMIA
Change from baseline in the FMIA (Frankfort-Mandibular Incisor Angle), measured in degrees (°) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment FMIA value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in S-Go Ratio
Change from baseline in the S-Go ratio, expressed as a percentage (%) on standardized lateral cephalometric radiographs. The ratio represents the posterior facial height (S-Go) relative to the anterior facial height (N-Me). The change will be calculated for each participant by comparing the post-treatment S-Go ratio with the participant's baseline ratio. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in UI-SN
Change from baseline in the UI-SN angle (Upper Incisor to SN Plane), measured in degrees (°) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment UI-SN value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in Interincisal Angle (U1/L1)
Change from baseline in the interincisal angle (U1/L1), measured in degrees (°) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment interincisal angle value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in U1/NA Angle
Change from baseline in the U1/NA angle (Upper Incisor to NA), measured in degrees (°) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment U1/NA angle value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in U1/NA Linear Measurement
Change from baseline in the linear U1/NA measurement (Upper Incisor to NA), measured in millimeters (mm) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment U1/NA linear measurement with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in L1/NB Angle
Change from baseline in the L1/NB angle (Lower Incisor to NB), measured in degrees (°) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment L1/NB angle value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months
Change in L1/NB Linear Measurement
Change from baseline in the linear L1/NB measurement (Lower Incisor to NB), measured in millimeters (mm) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment L1/NB linear measurement with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in Nasolabial Angle (Cotg-Sn-Ls)
Change from baseline in the nasolabial angle (Cotg-Sn-Ls), measured in degrees (°) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment nasolabial angle value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in Z Angle
Change from baseline in the Z angle (Merritt), measured in degrees (°) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment Z angle value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in N-Pog-H Line (H Angle)
Change from baseline in the N-Pog-H angle (H angle, Holdaway), measured in degrees (°) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment N-Pog-H angle value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in Ls-NsPog (U lip /E line)
Change from baseline in the Ls-NsPog (upper lip to E-line) measurement, measured in millimeters (mm) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment Ls-NsPog value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months
Change in Li-NsPog (Lower Lip / E-Line)
Change from baseline in the Li-NsPog (lower lip to E-line) measurement, measured in millimeters (mm) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment Li-NsPog value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in Sn-Stm : Stm-Me Ratio
Change from baseline in the Sn-Stm : Stm-Me ratio (Legan and Burstone), expressed as a percentage (%), representing the ratio of the upper lip height (Sn-Stm) to the lower lip and chin height (Stm-Me) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment ratio with the participant's baseline ratio. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in Gl-Sn-Pog (Facial Contour Angle)
Change from baseline in the Gl-Sn-Pog facial contour angle (Glabella-Subnasale-Pogonion), representing the soft tissue angle of facial convexity, measured in degrees (°) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment Gl-Sn-Pog angle value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in UFH (Upper Facial Height)
Change from baseline in the upper facial height (UFH), measured in millimeters (mm) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment UFH value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in LFH (Lower Facial Height)
Change from baseline in the lower facial height (LFH), measured in millimeters (mm) on standardized lateral cephalometric radiographs. The change will be calculated for each participant by comparing the post-treatment LFH value with the participant's baseline value. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Change in UFH: LFH ratio
Change from baseline in the UFH: LFH ratio (Upper Facial Height to Lower Facial Height), expressed as a percentage (%) on standardized lateral cephalometric radiographs. The ratio represents the upper facial height (UFH) relative to the lower facial height (LFH). The change will be calculated for each participant by comparing the post-treatment UFH:LFH ratio with the participant's baseline ratio. The changes will then be compared between the Myobrace and Frankel III groups. Baseline and at treatment completion, defined as when anterior crossbite correction is achieved or at 18 months, whichever occurs first.
Time frame: Baseline, and up to 18 months.
Plan to share: No — Individual participant data will not be shared with other researchers. The study data will be used for the purposes of the current research and reported in aggregate form to protect participant confidentiality and privacy.
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Sana'a University