What is the project?                                                                                                                                       

SIXES is a randomised control trial (RCT). Its aim is to provide new evidence as to whether ‘compensating extraction’, removal of the upper first permanent molar (FPM) to prevent its over-eruption, is necessary when removal of a child’s lower FPM is planned.  Although current Royal College guidance recommends this, uncertainty amongst clinicians means that some follow these guidelines and others do not. As a result children may be undergoing additional surgical procedures when there is no proven benefit. SIXES will investigate the clinical effectiveness, and quality of life for conventional treatment (following the guidelines) compared with removal of lower FPM, but with no compensating extraction of the upper FPM.    

Who is running the trial?

Professor David Bearn from the Dundee Dental Hospital and School, University of Dundee is the Chief Investigator with responsibility for the conduct of the trial.  Co-investigators Dr Nicola Innes, Dr Felicity Borrie and Dr Dafydd Evans are actively involved in study management and recruitment activities. The trial is co-sponsored by the University of Dundee and NHS Tayside. Tayside Clinical Trials Unit are providing trial management. 

Who is funding the trial?

The British Orthodontic Society Foundation.

Who has approved the trial?

SIXES has been approved by East of Scotland Research Ethics Services (REC 1). This Committee gave ethical permission for the trial to be conducted across Scotland and England. The study has been adopted by the Scottish Primary Care Research Network.

What will be the benefits of the trial?

Extraction of FPMs in children is common. Currently dentists and orthodontists face a dilemma in clinical decision-making. This trial will provide evidence to support practice and inform new guidance. Should the trial find the procedure to be unnecessary, it will result in a reduction in the number of teeth extracted, with implications for children and their carers, as well as providers and commissioners of dental services.

Which dentists can participate in the trial?

Community and hospital based dentists who see and treat child patients, and who are willing to undergo study related training.  Participating dentists will be asked to recruit between 12 and 20 children over a 24 month period.  Recruitment started in Spring 2014 and will continue until Spring 2016.

Interested in taking part?

Which patients are eligible to participate in the study?

The trial aims to recruit 400 children across Scotland and England, aged 7-11 years requiring extraction of a lower FPM but where the upper FPM(s) has a good prognosis. They will need to be able to co-operate with dental treatment and agree to participate.

Parent Information Sheet

Child Information Sheet


Study Sites

Dundee Dental Hospital - Recruiting
Broxden Community Dental Service - Recruiting
Dental Department, Kingscross Hospital -  Recruiting
Springfield Dental Centre, Arbroath (inlcuding Forfor, Brechin and Montrose) -
Dumfries & Galloway - Recruiting

The Research Team
For Parents and Children
Dentists Interested in Taking Part
Contact Us