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Study to Compare Two Functional Appliances for Class II Malocclusions

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details. Identifier: NCT03773783
Recruitment Status : Recruiting
First Posted : December 12, 2018
Last Update Posted : December 12, 2018
Information provided by (Responsible Party):
University of Birmingham

Tracking Information
First Submitted Date  ICMJE October 6, 2017
First Posted Date  ICMJE December 12, 2018
Last Update Posted Date December 12, 2018
Actual Study Start Date  ICMJE July 10, 2017
Estimated Primary Completion Date July 2019   (Final data collection date for primary outcome measure)
Current Primary Outcome Measures  ICMJE
 (submitted: December 11, 2018)
Change in overjet reduction [ Time Frame: Overjet measurement recorded at the start of treatment and at completion of functional appliance therapy 1 year later. ]
How quickly the horizontal discrepancy between upper and lower incisor edges is reduced
Original Primary Outcome Measures  ICMJE Same as current
Change History No Changes Posted
Current Secondary Outcome Measures  ICMJE
 (submitted: December 11, 2018)
  • Change in Peer Assessment Rating (PAR) [ Time Frame: PAR score will be Assessed from the start of treatment models and the end of fixed appliance study models ( 2 years later) ]
    PAR score change in terms of percentage and actual score
  • Drop out [ Time Frame: No. of patients at the start of functional appliance therapy that do not wish to continue within the trial or do not finish functional appliance therapy within 18 months ]
    Percentage of patients dropping out of each arm of the trial
  • Skeletal changes [ Time Frame: Cephalometric x-rays at start of treatment and at the end of treatment 1 year later ]
    Compare skeletal changes of landmarks in degrees and millimetres using cephalometric x-rays at various time points
  • 3D soft tissue measures [ Time Frame: 3D photographs at start of treatment and at the end of treatment (approx 1 year later) ]
    Measure changes in soft tissues using 3D photographs
  • Patient satisfaction [ Time Frame: Patient satisfaction survey at study completion ( 1 year after treament started) ]
    Use of tailored patient satisfaction questionnaire to assess patient satisfaction with both appliances
  • Child related Oral health quality of life (OHRQoL) questionnaire [ Time Frame: The patient ticked the applicable box for the 16 set questions from the standardised qualitative oral health questionairre. This was undertaken at the start of the trial and again at the end of functional appliance therapy ( approximately 1 year later) ]
    Changes in OHRQoL
  • Adverse events [ Time Frame: Adverse events over the course of functional appliance treatment ( recorded at every visit and reviewed at 1 year) ]
    Adverse events: decalcification, dental caries, soft tissue trauma, ingestion or aspiration of appliance
Original Secondary Outcome Measures  ICMJE Same as current
Current Other Pre-specified Outcome Measures Not Provided
Original Other Pre-specified Outcome Measures Not Provided
Descriptive Information
Brief Title  ICMJE Study to Compare Two Functional Appliances for Class II Malocclusions
Official Title  ICMJE Effectiveness of Treatment for Class II Malocclusions With the Button & Bead or Twin-block Functional Appliance: A Single Centre Randomised Clinical Trial
Brief Summary

A randomised controlled clinical trial to compare the effectiveness of two functional appliances in the correction of a Class II malocclusion. (Class II malocclusions are where upper front teeth bite significantly further forward in relation to lower front teeth).

Null hypothesis:

There is no significant difference between the Button & bead and Twin-block appliances with regard to time taken to reduce the overjet

Detailed Description


A functional appliance is a type of brace used to help correct a 'Class II' malocclusion. Class II malocclusions are where upper front teeth bite significantly further forward in relation to lower front teeth. A functional appliance is defined as a brace that engages upper and lower teeth and works mainly by posturing the lower jaw away from its normal position1. The functional appliance may either be removable or fixed in nature and of various designs.

Correction of a class II malocclusion can be commenced early i.e. before the age of 10 or during early adolescence when the patient is in a late mixed dentition / early permanent dentition. If correction is commenced early, this results in the need for a two phase treatment which involves functional appliance treatment in the first phase (age 7-10) followed by fixed appliances (+/- functional appliances) as an adolescent (age 11-16). If correction is started in early adolescence only one phase of treatment is required which involves a combination of functional and fixed appliances (age 11-16).

Early or delayed class II treatment has been studied by various researchers2-10. O'Brien et al7 concluded that there was no advantage of early treatment with Twin Block as compared to treatment started in adolescents. In fact, they reported significantly poorer occlusal outcomes as determined by the objective Peer Assessment Rating (PAR) index in those that had early treatment. In addition, they found that total duration of treatment, total attendances and total cost of treatment was significantly higher in the early treatment group. The average total duration of treatment for those that had early treatment was 968 days (phase 1 = 527 days and phase 2 = 435 days) compared to 744 days for those that had treatment as an adolescent only.

The most commonly used brace to correct class II malocclusions in the UK is a functional appliance (Twin Block design) 11.

The Button and Bead functional appliance has been developed and used successfully by Mr Spary (Consultant Orthodontist) for several years. However, there are no studies to date that have studied its effectiveness in correcting a class II problem. The Button and bead appliance appears to be quicker at reducing the overjet and preferred by patients as there is less mouth opening making the appliance more comfortable to wear. It is also two clear aligners, which are more aesthetic than the traditional twin block appliance. The button and bead appliance does not however allow arch expansion. This may necessitate another appliance prior to fixed appliance treatment or prolong fixed appliance treatment if expansion also needs to be carried out in that phase.


  1. Primary objective:

    a. To compare the Button-&-bead and Twin-block appliances treatment duration for overjet reduction

  2. Secondary objectives:

    1. To compare the Button-&-bead and Twin-block appliances dento-occlusal outcomes as measured by the Peer Assessment Rating (PAR)
    2. To compare patient compliance with the Button-&-bead and Twin-block appliances and identify causes for failure
    3. To compare the health economics of the Button-&-bead and Twin-block appliances (Cost of appliances, number of visits, number and cost of repairs and/or replacements)
    4. To compare the skeletal changes of the Button-&-bead and Twin-block appliances based on the Eastman analysis
    5. To compare changes in soft tissue profile as assessed by 3D photographs
    6. To assess changes in OHRQoL after overjet reduction with the Button-&-bead and Twin-block appliances
    7. To evaluate and compare patient satisfaction with the Button-&-bead and Twin-block appliances
  3. Safety objective

    1. To evaluate the safety of the Button-&-Bead appliance relative to the Twin-Block appliance in terms of the occurrence of any device-related adverse- and side-effects (soft-tissue trauma, decalcification, dental caries, ingestion or aspiration of appliance).
Study Type  ICMJE Interventional
Study Phase  ICMJE Not Applicable
Study Design  ICMJE Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double (Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Condition  ICMJE Malocclusion, Angle Class II
Intervention  ICMJE
  • Device: Button and Bead appliance
    Button and Bead appliance
  • Device: Twin Block appliance
    Twin Block appliance
Study Arms  ICMJE
  • Active Comparator: Twin Block
    Twin Block appliance
    Intervention: Device: Twin Block appliance
  • Experimental: Button and Bead
    Button and Bead appliance
    Intervention: Device: Button and Bead appliance
Publications *

*   Includes publications given by the data provider as well as publications identified by Identifier (NCT Number) in Medline.
Recruitment Information
Recruitment Status  ICMJE Recruiting
Estimated Enrollment  ICMJE
 (submitted: December 11, 2018)
Original Estimated Enrollment  ICMJE Same as current
Estimated Study Completion Date  ICMJE July 2020
Estimated Primary Completion Date July 2019   (Final data collection date for primary outcome measure)
Eligibility Criteria  ICMJE

Inclusion Criteria:

  • * Overjet ≥ 7mm

    • The normal overjet for a Caucasian population is in the range of 2-4mm. A functional appliance is used to allow for overjet reduction without extractions and/or to reduce the anchorage demands of the subsequent treatment with the Straight Wire Appliance (SWA). Clinically the overjet would need to be significantly increased for the treating clinician to consider the use of a functional appliance. Other similar studies have used an overjet of >6mm or ≥ 7mm. This study has elected for an initial overjet of ≥ 7mm to improve the studies external validity by making it more applicable to day-to-day clinical practice.
    • The initial overjet will be used to select patients. The majority of recent high level trials and systematic reviews that have provided a significant amount of the evidence base in the treatment of Class II malocclusions have defined subjects according to their initial overjet.

      * Age 10 to 14 years

    • This has been selected to match other studies relating to functional appliance treatment and reflect the most common clinical practice. The literature on functional appliance treatment has provided evidence that on average the enhancement of growth is small. Some studies on the timing of functional appliance treatment have suggested that pubertal growth is not a significant factor in the success of functional appliance treatment but it is well know and accepted that functional appliance treatment is assisted during periods of more rapid growth. Numerous studies have also found better co-operation and completion of treatment in younger patients (Banks 2004, KOB 2003a & 2003b)

      * Satisfactory Dental health

    • Patients must be dentally healthy and have a suitable level of oral health that would support orthodontic treatment, as per the British Orthodontic Society guidelines. They must have good oral hygiene with minimal gingivitis or periodontal disease, no dental caries or periapical pathology and no history of dento-alveolar trauma. This is judged by the investigator.

      • Willing to participate in study and provide informed consent

Exclusion Criteria:

  • * No previous orthodontic treatment or premolar extractions

    • This is aimed at reducing any confounding factors within the study as these may affect the success of treatment.

      * No craniofacial syndrome (including Cleft patients)

    • This is aimed at reducing any confounding factors within the study as these conditions may affect the success of treatment. The treatment of this subgroup requires a multi-disciplinary team and is more complex. Their treatment pathway may vary from normal clinical practice.
Sex/Gender  ICMJE
Sexes Eligible for Study: All
Ages  ICMJE 10 Years to 14 Years   (Child)
Accepts Healthy Volunteers  ICMJE Yes
Contacts  ICMJE
Contact: Sheena Kotecha, FDS MPhil (+44)07940544164
Contact: Thomas Dietrich
Listed Location Countries  ICMJE United Kingdom
Removed Location Countries  
Administrative Information
NCT Number  ICMJE NCT03773783
Other Study ID Numbers  ICMJE RG_16-204
Has Data Monitoring Committee Yes
U.S. FDA-regulated Product
Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No
IPD Sharing Statement  ICMJE
Plan to Share IPD: No
Responsible Party University of Birmingham
Study Sponsor  ICMJE University of Birmingham
Collaborators  ICMJE Not Provided
Investigators  ICMJE
Principal Investigator: Thomas Dietrich University of Birmingham
PRS Account University of Birmingham
Verification Date December 2018

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP