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A Prospective Randomized Controlled Trial to Evaluate the Effectiveness of the Two Different Appliances in the Treatment of Class II Division 1 Malocclusion

This study has been terminated.
(Study stopped due to increased harm and slow progress in the intervention group.)
National Health Service, United Kingdom
Information provided by:
University of Manchester Identifier:
First received: August 11, 2009
Last updated: NA
Last verified: August 2009
History: No changes posted
Twin-Block treatment and Dynamax treatment for Class II division 1 malocclusion do not have different effects with regards to treatment duration, the quality of dento-occlusal outcome, skeletal and soft tissue profile, patient discomfort and gingival health.

Condition Intervention
Class Ii Division 1 Malocclusion Other: Dynamax appliance Other: Twin-block appliance

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Treatment

Further study details as provided by University of Manchester:

Primary Outcome Measures:
  • Duration of treatment with functional appliance
  • Overjet measurement

Secondary Outcome Measures:
  • Harms Breakages Number of treatment visits Total treatment time Quality of occlusal result (PAR Index) Restricted cephalometric (radiograph) analysis Patient perception questionnaire at six months into treatment

Enrollment: 64
Study Start Date: January 2007
Study Completion Date: September 2008
Primary Completion Date: September 2008 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Functional appliance Other: Dynamax appliance Other: Twin-block appliance

Detailed Description:

The Dynamax appliance is a relatively new appliance for the treatment of Class II malocclusion and was introduced in 2003. The appliance has the theoretical advantages of incremental mandibular advancement without the need for bite registration, and the ability for the operator to simultaneously provide the functional and fixed appliance phases of treatment. Furthermore, the Dynamax appliance is designed to limit lower both lower incisor proclination and upper incisor retroclination without an increase in lower facial height. There has been limited research into this appliance and only one trial has been carried out. In this study the effects of the Dynamax were compared with the Twin-block, unfortunately, the trial was not carried out to contemporary standards and suffered from severe shortcomings. For example, the non compliance rate was not accounted for in the sample size calculation, the randomisation sequence was not clear, the investigators did not carry out an intention-to-treat analysis, the statistical analysis was simplistic and the study was carried out in a single dental school setting. This raises the question about the efficiency of the Dynamax appliance and whether or not they are effective in a 'real' world setting.

The aim of this study is to compare the effectiveness of the Dynamax appliance and the Twin-block appliance for the treatment of Class II Division 1 malocclusion.


Ages Eligible for Study:   10 Years to 14 Years   (Child)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Patients with a Class II malocclusion as defined by British Standards Institute classification.
  • Overjet greater than 6mm
  • Aged 10-14 years
  • Clinical examination indicates a functional appliance is not contraindicated

Exclusion Criteria:

  • Orthognathic treatment is required or there is a strong indication it will be required in the future
  • Possession of a craniofacial anomaly
  • Previous orthodontic treatment and/or premolar extraction
  • Hypodontia of more than one teeth in any quadrant excluding third molars
  • Inadequate oral hygiene
  Contacts and Locations
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Please refer to this study by its identifier: NCT00957489

United Kingdom
Chesterfield Royal Hospital
Chesterfield, United Kingdom
Derby Royak Hospital NHS Trust
Derby, United Kingdom
Sponsors and Collaborators
University of Manchester
National Health Service, United Kingdom
Principal Investigator: Kevin O'Brien, BDS, MSc, FDSRCS, DORth, PhD Prof of Orthodontics/ Associate Dean Teaching and Learning, University of Manchester
Principal Investigator: Jonathan Sandler, BDS, MSc, FDSRCS, MOrth RCS Consultant Orthodontist, Chesterfield NHS Trust
Principal Investigator: Alison Murray, BDS, MSc, FDSRCS, MORth RCS Consultant Orthodontist, Derby NHS Trust
Study Director: Badri ` Thiruvenkatachari, BDS, MDS, MOrth RCS, PhD Clinical Teaching Fellow in Orthodontics, University of Manchester
  More Information

Responsible Party: Kevin O'Brien, University of Manchester Identifier: NCT00957489     History of Changes
Other Study ID Numbers: DTT project
Study First Received: August 11, 2009
Last Updated: August 11, 2009

Keywords provided by University of Manchester:
Orthodontic treatment of Class II division 1 malocclusion

Additional relevant MeSH terms:
Tooth Diseases
Stomatognathic Diseases processed this record on September 21, 2017