Comparison of Early Interceptive Orthodontic Appliances (Traditional and Novel) and Later Fixed Appliance Treatment in Class II Malocclusion. (MACTWin)

February 7, 2026 updated by: Anna Westerlund, Vastra Gotaland Region

Early Interceptive (Headgear-Activator, Twin Block, Invisalign MA) Versus Later Fixed Appliance Treatment in Class II Malocclusion: A Randomized Clinical Trial

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:

  • Headgear-activator
  • Twin-block
  • Aligner Mandibular advancement
  • Control

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:

  • Baseline (T0)
  • 9 months into treatment (T1)
  • End of treatment (T2) Appliance checks will occur every 8 weeks. Digital scans of the occlusion will be collected at T0, T1, and T2. Lateral cephalometric radiographs will be taken at T0 and T2.

Outcomes and planned analyses

The trial will generate three studies with distinct outcomes:

  1. Treatment outcomes Primary outcome: dental treatment effectiveness measured as overjet reduction. Secondary outcomes: other dental variables, skeletal outcomes, and extraoral outcomes.

  2. Patient-reported outcomes

    All treated patients will complete two digital questionnaires:

    • Child Perception Questionnaire (CPQ): assesses the child's perception of their teeth before and after treatment.
    • Orthodontic Treatment Impact Questionnaire (OTIQ): assesses the child's experience of orthodontic treatment and the appliance.

    These outcomes will be used to evaluate changes in OHRQoL from pre- to post-treatment and to compare experiences across treatment modalities.

  3. 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.

    • Direct costs: premises, staff salaries, materials, and laboratory costs.
    • Indirect costs: parental loss of income due to absence from work.
    • Societal costs: direct + indirect costs. Costs will be related to treatment outcomes to estimate cost-effectiveness across the treatment arms.

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.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
144

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • Sweden
      • Gothenburg, Sweden, 40530
        • Sahlgrenska Academy
      • Halmstad, Sweden, 30246
        • Orthodontic Specialist Clinic
      • Kungsbacka, Sweden, 43441
        • Orthodontic Specialist Clinic

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Child

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Children age 9-13 years at the start of the trial
  • Mixed dentition, DS3M1
  • Excessive overjet ≥6 mm
  • First permanent molars in at least half cusp Cl II relation bilaterally
  • Incomplete lip closure

Exclusion Criteria:

  • Treatment needing extractions due to severe crowding
  • Earlier orthodontic treatment
  • Mouth breathing
  • Ongoing sucking habits
  • Syndromic patients

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Head gear activator
Treatment with head gear activator orthodontic appliance.
Device: Head gear activator
Activator with extra orala head gear traction
Experimental: Twin Block
Treatment with Twin Block appliance
Device: Twin Block
Twin Block orthodontic appliance
Experimental: Invisalign Mandibular Advancement
Treatment with Invisalign mandibular advancement featuring occlusal blocks.
Device: Invisalign mandibular advancement
Invisalign mandibular advancement featuring occlusal blocks
Experimental: Fixed appliance
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
Fixed appliance in upper and lower jaw

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Part I: Dental treatment result: Overjet reduction
Time Frame: 18 months
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.
18 months

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Part I: Dental treatment result: Sagittal relation, overbite
Time Frame: 18 months

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.
18 months

Other Outcome Measures

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Part I: Basal treatment result
Time Frame: 18 months
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.
18 months
Part I: Extra oral treatment result
Time Frame: 18 months
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.
18 months
Part II: Oral Health Related Quality of life (ORHQoL)
Time Frame: 18 months
Changes in OHRQoL from baseline compared to end of the treatment. Unit: OHRQoL score (higher = worse)
18 months
Part II: Patient experience of the orthodontic treatment
Time Frame: 18 months
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
18 months
Part III: Direct costs
Time Frame: 18 months
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).
18 months
Part III: Indirect costs
Time Frame: 18 months
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).
18 months
Part I: Societal costs
Time Frame: 18 months
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).
18 months

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Vastra Gotaland Region

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Göteborg University
Region Halland
Västra Götalandsregionen

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Anna Westerlund, Professor, Department of Orthodontics, Institution of Odontology, Sahlgrenska Academy, University of Gothenburg

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
January 15, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
March 1, 2031

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
March 1, 2031

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 17, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 7, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
February 11, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
February 11, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 7, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
February 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • RCT: Comparing Class II TX

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

IPD Plan Description

Charing individual patient data is not approved in the ethical approval.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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