Malocclusion, Angle Class IINCT07752498
Long-term Stability of Treatment With the Twin Block Appliance
An observational study of Malocclusion, Angle Class II and Overbite (Excessive) Horizontal, run by Region Jönköping County at 1 site in Sweden.
Trial summary
The objective of this observational study is to investigate the long-term stability of treatment with the Twin block appliance in a patient group previously treated with a Twin block appliance. The main questions it aims to answer are: 1. Read more about this study
- Who is it for?
- Any age
- Conditions the study is for
- Malocclusion, Angle Class II, Overbite (Excessive) Horizontal, Overbite (Excessive) Deep
- How many people
- 72 participants
- Where
- 1 siteSweden
- Study dates
- 10 Jul 2026to 20 Dec 2026
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages Any age
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Study population: The patient cohort was originally recruited and treated from December 2018 to October 2020 The inclusion criteria for the previous study were healthy patients according to the American Society of Anaesthesiology Classification (ASA I and II), aged 8-14 years at treatment start and with an overjet of 6 mm or more together with an incomplete lip closure. Exclusion criteria were severe chronic conditions such as asthma and allergy, neuropsychiatric disorders, craniofacial syndromes, and previous orthodontic treatment. Recruitment of the patients continued until the number of participants met the estimated sample size. This patient group were then contacted again for recruitement to the present study during June 2026 to August 2026.
Who may be able to join
- Patient participated in the previous study "Patient compliance with Twin Block appliance during treatment of Class II malocclusion: a randomized controlled trial on two check-up prescriptions" .Eur J Orthod. 2023. https://doi.org/10.1093/ejo/cjac046
Who cannot join
- None
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Sweden1 site
The Institute of Postgraduate Dental Education
Jönköping, Jönköping County, 551 11
About this study
The objective of this observational study is to investigate the long-term stability of treatment with the Twin block appliance in a patient group previously treated with a Twin block appliance. The main questions it aims to answer are:
- Does treatment with the Twin block appliance give a lasting treatment result or does the bite relapse over time due to different factors such as short treatment time, compliance or the patient's natural growth pattern?
- How many patients that had received treatment with Twin block appliance required additional treatment with fixed appliances and for what reason?
Researchers will compare the patients present bite at (T2) by using study casts and cephalometric x-rays and compare this data with previous registrations made pre- (T0) and post-treatment (T1). Additional factors, such as how much relapse a patient has on average, will also be investigated.
Read the detailed description
Orthodontic treatment during growth is called interceptive orthodontics. The objective is to affect the growth of the jaws and the position of the teeth with the assistance of a removable orthodontic appliance. One such appliance is the Twin block appliance, which is used to treat patients with an Angle class II malocclusion (Clark et al., 2022). The prevalence of Angle class II malocclusion is approximately 25% (Proffit et al., 2013).
There is however a lack of studies on the long term treatment stability of the Twin block appliance (Ehsani et al., 2015). Treatment with removable appliances also carry a great cost for both the individual, the parents and for society as a whole (Permert et al., 1998). The objective of the present study is to present guidelines concerning which patients that would benefit the most from treatment with Twin block appliance over time.
The present study will use a previous patient material consisting of 72 patients from the study by Frilund et al., (2023) "Patient compliance with Twin Block appliance during treatment of Class II malocclusion: a randomized controlled trial on two check-up prescriptions" to review the long term stability of treatment with Twin block appliance. These 72 patients were previously treated with a Twin block appliance. Their records will be reviewed to find patients who have had no additional orthodontic treament, and these patients will be asked to participate in the present study. If they accept, their present bite (T2) will be registered by study casts and with a cephalometric x-ray. This data (T2) will then be compared with their study casts and cephalometric data before treatment start (T0) and after treatment (T1). The main variables that will be investigated are overjet, overbite and molar relationship, as well as cephalometric values. The collected material will also be dichotomized into two groups, one with optimal current status with a neutral molar relation and a horizontal overjet of 4 mm or less, and one with a suboptimal current status presenting an angle class II molar relationship and/or an overjet greater that 4 mm.
The patients that recieved additional orthodontic treatment after their treatment with Twin block appliance will also be investigated to compare the reason for them having additional treatment and to investigate if the primary reason was relapse or other additional factors.
Statistical analysis of collected data will be perfofmed with the appropriate stastical models, depending on if the data has a normal distribution or not.
The study has recieved ethical approval from the ethical board at the University of Linköping, Dnr 2025-08312-02. All patients will have to give their informed consent to participate in the study by signing a consent form.
Results will be published in appropriate medical journals and at interdisciplinary conferences and lectures.
- Conditions
- Malocclusion, Angle Class II, Overbite (Excessive) Horizontal, Overbite (Excessive) Deep, Treatment Outcome, Orthodontic Appliances, Removable
- Keywords
- Removable appliance, Twin Block, Long-term stability
- Medical subject headings
- Malocclusion, Angle Class II, Overbite
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| Long term follow-up without additional orthodontic treatment | Patients that recieved treatment with Twin block, without having recieved additional treatment afterwards. | |
| Long term follow-up with additional orthodontic treatment | Patients that recieved treatment with Twin block and then also required additional treatment afterwards. |
What is being measured
The primary outcome is the main question the study is designed to answer.
Difference in horisontal overjet
The difference in horisontal overjet measured in millimeters at follow up (T2), compared with pre- (T0) and post-treatment (T1) values.
Measured: From enrollment (T0) to follow up (T2), about 6 years later.
Secondary outcomes (3)
Molar relationship
Molar relationship at follow-up (T2), compared to molar relationship pre-(T0) and post-treatment (T1).
Measured: From enrollment (T0) to follow up (T2), about 6 years later.
Overbite
The difference in vertical overjet measured in millimeters at follow up (T2), compared with pre- (T0) and post-treatment (T1) values.
Measured: From enrollment (T0) to follow up (T2), about 6 years later.
Cephalometric data
Comparing cephalometric values of SNA, SNB and ANB pre- (T0), post-treatment (T1) and at follow-up (T2).
Measured: From enrollment (T0) to follow up (T2), about 6 years later.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted7 Aug 2026
- Study start10 Jul 2026
- Primary completion30 Aug 2026 (estimated)
- Study completion20 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (5)Papers the sponsor has linked to this study.
- Other trials for Malocclusion, Angle Class IIStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 72 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Region Jönköping County
- Sponsor type
- Other government
- Responsible party
- Sponsor
- Investigators
- Anders Magnusson, Med dr., Principal investigator, Region Jönköping
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07752498
- Sponsor's protocol ID
- Dnr 2025-08312-02
- Status last verified
- Jul 2026
- First submitted
- 3 Aug 2026
- Last updated
- 7 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided: Data collection is not yet complete.
Publications
Permert L, Karlander EL, Wilhelm E. Treatment of malocclusions in children and adolescents at a public dental service clinic in Sweden: extent and cost. Swed Dent J. 1998;22(5-6):187-93.
PubMed 9974202Cacciatore G, Ugolini A, Sforza C, Gbinigie O, Pluddemann A. Long-term effects of functional appliances in treated versus untreated patients with Class II malocclusion: A systematic review and meta-analysis. PLoS One. 2019 Sep 6;14(9):e0221624. doi: 10.1371/journal.pone.0221624. eCollection 2019.
PubMed 31490945Ehsani S, Nebbe B, Normando D, Lagravere MO, Flores-Mir C. Short-term treatment effects produced by the Twin-block appliance: a systematic review and meta-analysis. Eur J Orthod. 2015 Apr;37(2):170-6. doi: 10.1093/ejo/cju030. Epub 2014 Jul 22.
PubMed 25052373O'Brien K, Wright J, Conboy F, Chadwick S, Connolly I, Cook P, Birnie D, Hammond M, Harradine N, Lewis D, McDade C, Mitchell L, Murray A, O'Neill J, Read M, Robinson S, Roberts-Harry D, Sandler J, Shaw I, Berk NW. Effectiveness of early orthodontic treatment with the Twin-block appliance: a multicenter, randomized, controlled trial. Part 2: Psychosocial effects. Am J Orthod Dentofacial Orthop. 2003 Nov;124(5):488-94; discussion 494-5. doi: 10.1016/S0889540603006425.
PubMed 14614414Frilund E, Sonesson M, Magnusson A. Patient compliance with Twin Block appliance during treatment of Class II malocclusion: a randomized controlled trial on two check-up prescriptions. Eur J Orthod. 2023 Mar 31;45(2):142-149. doi: 10.1093/ejo/cjac046.
PubMed 35968672
Study at a glance
From the registry record, last updated by the sponsor on 7 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Long-term Stability of Treatment With the Twin Block Appliance
- ClinicalTrials.gov ID
- NCT07752498
- Acronym / sponsor ID
- Dnr 2025-08312-02
- Conditions
- Malocclusion, Angle Class II, Overbite (Excessive) Horizontal, Overbite (Excessive) Deep, Treatment Outcome, Orthodontic Appliances, Removable
- Keywords
- Removable appliance, Twin Block, Long-term stability
- Study type
- Observational
- Recruitment status
- Enrolling by invitation
- Enrolment
- 72 participants (estimated)
- Lead sponsor
- Region Jönköping CountyOther government
- Study start
- 10 Jul 2026 (actual)
- Primary completion
- 30 Aug 2026 (estimated)
- Study completion
- 20 Dec 2026 (estimated)
- First posted
- 7 Aug 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The objective of this observational study is to investigate the long-term stability of treatment with the Twin block appliance in a patient group previously treated with a Twin block appliance. The main questions it aims to answer are:
- Does treatment with the Twin block appliance give a lasting treatment result or does the bite relapse over time due to different factors such as short treatment time, compliance or the patient's natural growth pattern?
- How many patients that had received treatment with Twin block appliance required additional treatment with fixed appliances and for what reason?
Researchers will compare the patients present bite at (T2) by using study casts and cephalometric x-rays and compare this data with previous registrations made pre- (T0) and post-treatment (T1). Additional factors, such as how much relapse a patient has on average, will also be investigated.
Detailed description
Orthodontic treatment during growth is called interceptive orthodontics. The objective is to affect the growth of the jaws and the position of the teeth with the assistance of a removable orthodontic appliance. One such appliance is the Twin block appliance, which is used to treat patients with an Angle class II malocclusion (Clark et al., 2022). The prevalence of Angle class II malocclusion is approximately 25% (Proffit et al., 2013).
There is however a lack of studies on the long term treatment stability of the Twin block appliance (Ehsani et al., 2015). Treatment with removable appliances also carry a great cost for both the individual, the parents and for society as a whole (Permert et al., 1998). The objective of the present study is to present guidelines concerning which patients that would benefit the most from treatment with Twin block appliance over time.
The present study will use a previous patient material consisting of 72 patients from the study by Frilund et al., (2023) "Patient compliance with Twin Block appliance during treatment of Class II malocclusion: a randomized controlled trial on two check-up prescriptions" to review the long term stability of treatment with Twin block appliance. These 72 patients were previously treated with a Twin block appliance. Their records will be reviewed to find patients who have had no additional orthodontic treament, and these patients will be asked to participate in the present study. If they accept, their present bite (T2) will be registered by study casts and with a cephalometric x-ray. This data (T2) will then be compared with their study casts and cephalometric data before treatment start (T0) and after treatment (T1). The main variables that will be investigated are overjet, overbite and molar relationship, as well as cephalometric values. The collected material will also be dichotomized into two groups, one with optimal current status with a neutral molar relation and a horizontal overjet of 4 mm or less, and one with a suboptimal current status presenting an angle class II molar relationship and/or an overjet greater that 4 mm.
The patients that recieved additional orthodontic treatment after their treatment with Twin block appliance will also be investigated to compare the reason for them having additional treatment and to investigate if the primary reason was relapse or other additional factors.
Statistical analysis of collected data will be perfofmed with the appropriate stastical models, depending on if the data has a normal distribution or not.
The study has recieved ethical approval from the ethical board at the University of Linköping, Dnr 2025-08312-02. All patients will have to give their informed consent to participate in the study by signing a consent form.
Results will be published in appropriate medical journals and at interdisciplinary conferences and lectures.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Long term follow-up without additional orthodontic treatment | – | –Patients that recieved treatment with Twin block, without having recieved additional treatment afterwards. |
| Long term follow-up with additional orthodontic treatment | – | –Patients that recieved treatment with Twin block and then also required additional treatment afterwards. |
Who may qualify
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
- Study population
- The patient cohort was originally recruited and treated from December 2018 to October 2020 The inclusion criteria for the previous study were healthy patients according to the American Society of Anaesthesiology Classification (ASA I and II), aged 8-14 years at treatment start and with an overjet of 6 mm or more together with an incomplete lip closure. Exclusion criteria were severe chronic conditions such as asthma and allergy, neuropsychiatric disorders, craniofacial syndromes, and previous orthodontic treatment. Recruitment of the patients continued until the number of participants met the estimated sample size. This patient group were then contacted again for recruitement to the present study during June 2026 to August 2026.
Key inclusion criteria (1 listed)
- Patient participated in the previous study "Patient compliance with Twin Block appliance during treatment of Class II malocclusion: a randomized controlled trial on two check-up prescriptions" .Eur J Orthod. 2023. https://doi.org/10.1093/ejo/cjac046
Key exclusion criteria (1 listed)
- None
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
Difference in horisontal overjet
Time frame: From enrollment (T0) to follow up (T2), about 6 years later.
The difference in horisontal overjet measured in millimeters at follow up (T2), compared with pre- (T0) and post-treatment (T1) values.
3 secondary outcomes
Molar relationship
Time frame: From enrollment (T0) to follow up (T2), about 6 years later.
Overbite
Time frame: From enrollment (T0) to follow up (T2), about 6 years later.
Cephalometric data
Time frame: From enrollment (T0) to follow up (T2), about 6 years later.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 7 Aug 2026.
- Background: PubMed 9974202Permert L, Karlander EL, Wilhelm E. Treatment of malocclusions in children and adolescents at a public dental service clinic in Sweden: extent and cost. Swed Dent J. 1998;22(5-6):187-93.
- Background: PubMed 31490945Cacciatore G, Ugolini A, Sforza C, Gbinigie O, Pluddemann A. Long-term effects of functional appliances in treated versus untreated patients with Class II malocclusion: A systematic review and meta-analysis. PLoS One. 2019 Sep 6;14(9):e0221624. doi: 10.1371/journal.pone.0221624. eCollection 2019.
- Background: PubMed 25052373Ehsani S, Nebbe B, Normando D, Lagravere MO, Flores-Mir C. Short-term treatment effects produced by the Twin-block appliance: a systematic review and meta-analysis. Eur J Orthod. 2015 Apr;37(2):170-6. doi: 10.1093/ejo/cju030. Epub 2014 Jul 22.
- Background: PubMed 14614414O'Brien K, Wright J, Conboy F, Chadwick S, Connolly I, Cook P, Birnie D, Hammond M, Harradine N, Lewis D, McDade C, Mitchell L, Murray A, O'Neill J, Read M, Robinson S, Roberts-Harry D, Sandler J, Shaw I, Berk NW. Effectiveness of early orthodontic treatment with the Twin-block appliance: a multicenter, randomized, controlled trial. Part 2: Psychosocial effects. Am J Orthod Dentofacial Orthop. 2003 Nov;124(5):488-94; discussion 494-5. doi: 10.1016/S0889540603006425.
- Background: PubMed 35968672Frilund E, Sonesson M, Magnusson A. Patient compliance with Twin Block appliance during treatment of Class II malocclusion: a randomized controlled trial on two check-up prescriptions. Eur J Orthod. 2023 Mar 31;45(2):142-149. doi: 10.1093/ejo/cjac046.
- Individual participant dataSharing planned: Undecided. Data collection is not yet complete.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Anders Magnusson, Med dr. principal investigator
Region Jönköping
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Malocclusion, Angle Class II and Overbite (Excessive) Horizontal, run by Region Jönköping County at 1 site in Sweden.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: enrolling by invitation, as of the sponsor's last update on 7 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Sweden. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Difference in horisontal overjet (time frame: From enrollment (T0) to follow up (T2), about 6 years later.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07752498, which also lists 5 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 7 Aug 2026.