NCT02742493.

Study name	Effectiveness of 3 orthodontic retention schemes on post‐treatment stability and gingival recession
Methods	Study design: single‐centre, open‐label, 3‐armed, parallel, randomised, active‐control trial Country: Greece Duration of follow‐up: 1 year in retention, 2 years and 5 years Inclusion criteria  Both sexes Age between 10 and 16 years At the finishing stage of orthodontic treatment, programmed for debonding Class I to Class II molar relationship before the beginning of orthodontic treatment Non‐extraction treatment plan with fixed straight‐wire appliances Space deficiencies and irregularity of no more than 6 mm in the maxillary/mandibular arch (Irregularity Index) Exclusion criteria  No missing teeth, impacted teeth or other dental anomalies No congenital anomalies/syndromes
Participants	The study aims to enrol and randomise 60 participants.
Interventions	Group 1 (experimental intervention): lower fixed canine and canine retainer (0.028 inch stainless steel bonded to canines) and upper removable Hawley Group 2 (experimental intervention): lower fixed canine to canine retainer (7‐strand Twistflex 0.027 inch bonded to all 6 anterior teeth) and upper removable Hawley Group 3 (active comparator): lower Hawley‐type and upper Hawley removable retainer
Outcomes	Primary outcomes Stability ‐ LII, intercanine width, interpremolar width, intermolar width, arch length, overbite and overjet Secondary outcomes Survival rate ‐ bond failures of fixed retainers or breakages of removable ones Adverse effects ‐ gingival recessions
Starting date	19 April 2016
Contact information	Principal Investigator: Dr Despina Koletsi Institution: Department of Orthodontics, School of Dentistry, University of Athens, Greece Email: d.koletsi@gmail.com
Notes	Contacted study author, study ongoing