Design: A randomised controlled trial (RCT) was performed in a single orthodontic practice.
Intervention: The aim was to compare the clinical effectiveness of Hawley and vacuum-formed retainers (VFR) over a 6-month period of retention. Three hundred and ninety-seven patients were treated by a specialist orthodontist and randomly allocated to wear either Hawley retainers (n=196) or VFR (n=201).