An interventional study of Head gear activator and Twin Block in Class II Malocclusion, Class II Malocclusion, Division 1 and Overjet, sponsored by Vastra Gotaland Region. Not yet recruiting at 3 sites in Sweden. Open to participants aged 9 Years to 13 Years. Per ClinicalTrials.gov, last updated 2026-02-11.
Sponsored by Vastra Gotaland Region · Not applicable, Interventional, and Treatment
Background Approximately 15% of children have a Class II malocclusion, where the maxilla is positioned anterior to the mandible, and around 90% of these children also present with an increased overjet. Increased overjet is associated with a higher risk of dental trauma and psychosocial consequences such as bullying and reduced oral health-related quality of life (OHRQoL).
Functional orthodontic appliances (e.g., headgear-activator and Twin-block) have long been used to reduce overjet through dentoalveolar effects and by influencing mandibular position and growth. More recently, digital solutions such as Invisalign's mandibular advancement appliance have been introduced, with potential advantages including improved wear time and simultaneous tooth alignment. However, there is currently limited evidence regarding treatment outcomes, patient experience, and cost-effectiveness of these newer appliances compared with established functional appliances.
Aim The primary aim is to compare treatment outcomes, patient experience, and cost-effectiveness of interceptive orthodontic treatment using three different appliances. The overall aim is to determine whether interceptive treatment of Class II malocclusion with large overjet is effective, and if so, which interceptive modality should be preferred.
Study design and setting
A total of 144 patients aged 9-13 years with Class II malocclusion and large overjet will be randomized into four groups:
Participants will be treated at four Orthodontic Specialist Clinics within the National Health Service in Region Halland and Västra Götaland, Sweden. Treatments will be provided by two experienced orthodontic specialists.
Follow-up and data collection
Clinical examinations will be performed at:
Outcomes and planned analyses
The trial will generate three studies with distinct outcomes:
Patient-reported outcomes
All treated patients will complete two digital questionnaires:
These outcomes will be used to evaluate changes in OHRQoL from pre- to post-treatment and to compare experiences across treatment modalities.
Cost-effectiveness analysis The economic evaluation will include direct, indirect, and societal costs. Treatment duration, number and length of appointments, and cancellations/no-shows will be recorded.
Additional comparison: early vs late treatment Furthermore, after completing 18 months the control group, and half of the functional appliance patients will receive treatment with fixed appliances. This enables an additional comparison of early interceptive treatment versus later treatment using the same outcomes: treatment effectiveness, patient-reported outcomes, and cost-effectiveness.
124 studies on the registry are indexed under Malocclusion, Angle Class II; 19 are open to participants now.
This study's planned enrollment of 144 is above the median of 34 across 115 interventional studies indexed under Malocclusion, Angle Class II.
Browse Malocclusion, Angle Class II studies →Vastra Gotaland Region is the lead sponsor of 275 studies on the registry; 109 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:
Treatment with head gear activator orthodontic appliance.
Device: Head gear activator
Treatment with Twin Block appliance
Device: Twin Block
Treatment with Invisalign mandibular advancement featuring occlusal blocks.
Device: Invisalign mandibular advancement
Participants will serve as an observation (no treatment) control group during the trial period for 18 months. After completion of the observation phase, they will receive orthodontic treatment with fixed appliances. Outcomes from this delayed intervention will be compared with the three early intervention groups.
Device: Fixed appliance
Activator with extra orala head gear traction
Twin Block orthodontic appliance
Invisalign mandibular advancement featuring occlusal blocks
Fixed appliance in upper and lower jaw
Part I: Dental treatment result: Overjet reduction
Change in dental overjet compared to baseline. Unit: millimetres (mm). Direction of effect: Lower post-treatment overjet (i.e. greater reduction from baseline) indicates a better outcome; higher overjet values indicate a worse outcome.
Time frame: 18 months
Part I: Dental treatment result: Sagittal relation, overbite
Sagittal relationship at the end of treatment, evaluated by both molar and canine relationships. Unit: millimetres (mm). Direction of effect: Change towards Class I in molar and canine relation compared with baseline is favorable.
Time frame: 18 months
Part I: Basal treatment result
Skeletal treatment outcomes will be evaluated as changes in SNA, SNB, ANB, NL/ML, Wits, Ils/NL, Ili/ML, Ils/NA, and Ili/NB between baseline and the end of treatment. The measurements will be obtained from lateral cephalometric radiographs. Unit: degrees (°). Direction of effect: Non-linear; mid-range values are favourable, whereas both low and high values are clinically unfavourable.
Time frame: 18 months
Part I: Extra oral treatment result
Changes in profile angle and lip closure from before start of the treatment and end of the treatment. The mesurements will be done on standardized photographs. Unit: degrees (°). Direction of effect: Non-linear; mid-range values are favourable, whereas both low and high values are clinically unfavourable.
Time frame: 18 months
Part II: Oral Health Related Quality of life (ORHQoL)
Changes in OHRQoL from baseline compared to end of the treatment. Unit: OHRQoL score (higher = worse)
Time frame: 18 months
Part II: Patient experience of the orthodontic treatment
The results of the Orthodontic Treatment Impact Questionnaire (OTIQ) will be compared across all groups to evaluate patient experience with the different orthodontic appliances. Score- higher scores reflect more negative impact of treatment
Time frame: 18 months
Part III: Direct costs
The difference in direct costs between the different treatment alternatives. Unit: currency units per patient (e.g. EUR per completed treatment) Direction of effect: Lower values indicate lower direct costs (favourable).
Time frame: 18 months
Part III: Indirect costs
The difference in indirect costs between the different treatment alternatives. Unit: currency units per patient (e.g. EUR per completed treatment) Direction of effect: Lower values indicate lower direct costs (favourable).
Time frame: 18 months
Part I: Societal costs
The difference in societal costs between the treatment alternatives. Societal costs are defined as the sum of direct and indirect costs. Unit: currency units per patient (e.g. EUR per completed treatment) Direction of effect: Lower values indicate lower direct costs (favourable).
Time frame: 18 months
Plan to share: Undecided — Charing individual patient data is not approved in the ethical approval.
No publications or documents are linked to this record.
Start is estimated for Jan 2026; primary completion for Mar 2031, 61 months later.
Of 86 non-industry interventional studies with no phase under Malocclusion, Angle Class II, half reached primary completion within 15 months of starting (the median), counting those still running; a quarter within 11 and three quarters within 22. This study's planned 61 months is above that.
Counting every sponsor, half of 86 studies reached it within 15 months; a quarter within 11 and three quarters within 22.
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This study is not yet recruiting, as verified in Feb 2026. You cannot join it, but the record below documents what was studied.
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