Condition category
Oral Health
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
Sticking out front teeth is a common dental feature in the UK. It affects 20% of the white population. It affects the oral health and related quality of life in the adolescent population. Children who have upper front teeth sticking out are more susceptible to dental trauma or injury. Current evidence also suggests that they can be an easy target for being bullied at school. Sticking out front teeth can be corrected by seeking treatment from your local orthodontist. Usually, this is done by wearing a functional brace that maximises the potential growth of the lower jaw in order to keep up with the growth of the upper jaw. A functional brace works best on patients who are growing, thus the best time to treat this is when they are undergoing their pubertal growth spurt at the age of 12 years old for females and 14 years old for males. To date, functional braces could be classified into two broad categories: either a fixed functional appliance which is glued onto the teeth or a removable functional appliance. Research suggests that the most popular removable functional appliance in the UK is the twin-block appliance, whereas for the fixed functional appliance it is less clear. There are quite a few fixed functional appliances on the market. One that appears to work comparatively well is the Forsus fatigue resistant device (FRD). Both types of appliance work effectively. However, we are not entirely sure which is more effective at reducing the horizontal gaps between the upper and lower front teeth. Hence, this trial aims to answer this question.

Who can participate?
Adolescents with sticking out front teeth aged 12 to 14 years old can participate in this study.

What does the study involve?
Patients will be randomly allocated to either the Forsus FRD group or the twin-block group. They will need to wear the functional appliance for approximately 9 months (6 months full time and 3 months part time). They will then need to wear a glued-on train track brace for a further 20 months. The total treatment would be for about 30 months. All patients will be seen once every 6 to 8 weeks. At the end of each phase, they will have X-ray of their jaw (radiographs) taken. It is important to stress that there will be no additional X-ray exposure required. Patients' general dental practitioner will be informed regarding their involvement in the trial. Patients will also need to complete a questionnaire for feedback on the functional appliances.

What are the possible benefits and risks of participating?
There are no anticipated risks involved with the participation in this study. The use of the appliances and visits required would be same whether or not the child is involved in the study. There is a possibility that treatment with Forsus Functional appliance may lead to a shorter overall treatment time. However, we have no evidence to support this. The child’s participation in this trial would help to find out if this is the case.

Where is the study run from?
The study will be carried out at two orthodontic departments of the Northwest region, namely Stepping Hill Hospital at Stockport and University of South Manchester Hospital at Wythenshawe, UK.

When is study starting and how long is it expected to run for?
The data collection of the trial is expected to start in September 2013 and runs until September 2015. The results are expected to be published in 2016.

Who is funding the study?
This study is both funded and sponsored by Stockport NHS Foundation Trust, UK.

Who is the main contact?
Dr Maria McNally

Trial website

Contact information



Primary contact

Dr Maria McNally


Contact details

Stockport NHS Foundation Trust
Outpatient B Room 5
Poplar Grove
United Kingdom

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Comparison between twin-block appliance and Forsus™ fatigue resistant device in treating class II division I malocclusion: a randomised controlled trial


Study hypothesis

Twin-block removable functional appliance and Forsus™ Fatigue Resistant Device do not have any difference with regards to treatment duration, quality of dento-occlusal outcome, breakages and patient discomfort in treating Class II Div I malocclusion.

Ethics approval

Will be seeking with the local ethics committee in August 2013

Study design

Two centre randomised clinical controlled trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet


Sticking out upper front teeth is a variation of normal occlusion which is commonly associated with bullying, teasing and risk of trauma to the dentition. Treatment is aimed to improving the occlusal outcome and patients' self-esteem


All subjects who are eligible for inclusion will be interviewed and the purpose of the trial will be outlined. Patients will be given information leaflets on their first visit as well as a detailed explanation of the trial and they are required to provide us feedback on whether they are willing to participate in this trial. If they are, informed consent will be obtained and the operator will contact the central trial coordinator to provide details of subject. The subject will then be randomly allocated, stratifying for operator and gender, to either Twin-block appliance or Forsus FRD appliance. Patients will be treated according to the treatment protocols as outlined without any additional appointments for the sake of the trial. In addition, the following data will be collected from patients’ notes:
1. Number of attendances, including failed & cancelled appointments
2. Overall treatment duration
3. Frequency of appliance breakages, if any

Patients will also be required to fill in the Smiles Better questionnaires which will inform us how the appliances will affect them as part of the qualitative assessment.

Intervention type



Not Applicable

Drug names

Primary outcome measures

Treatment duration. All outocmes will be measured at baseline (T1) and at the end of active treatment (T2). Records will be taken at these time points which will include: study models, radiographs and pictures.

Secondary outcome measures

1. Quality of the dento-occlusal outcome measured on study models
2. Pancherz analysis on cephalograms
3. Qualitative assessment using questionnaires on how the appliances affect them
4. Breakages
5. Cost

Overall trial start date


Overall trial end date


Reason abandoned


Participant inclusion criteria

1. Patients with Class II Division I malocclusion
2. Overjet > 6mm
3. All permanent teeth erupted except second and third molars
4. Aged 10-15 years old

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Possible orthognathic treatment is required or there is a strong indication it will be required in the future
2. Presence of any craniofacial anomaly / syndrome
3. Maxillary mandibular plane angle of more than 37˚
4. Previous orthodontic treatment and/or premolar extraction
5. Hypoplastic permanent teeth – first molars
6. Hypodontia of any tooth in any quadrant excluding third molars
7. Subjects involved in any other orthodontic trials
8. Inadequate oral hygiene

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Stockport NHS Foundation Trust
United Kingdom

Sponsor information


Stockport NHS Foundation Trust (UK)

Sponsor details

c/o Jan Smith
F 08 Pinewood House Stepping Hill Hospital
Poplar Grove
United Kingdom

Sponsor type

Hospital/treatment centre



Funder type

Hospital/treatment centre

Funder name

Stockport NHS Foundation Trust (UK)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Results - basic reporting

Publication summary

Publication citations

Additional files

Editorial Notes