Scribante 2011.

Study characteristics
Methods	2‐arm parallel RCT
Participants	Number recruited: 34 Sex (M:F): 9:25 Mean age (years): 14.3 (SD not provided) Inclusion criteria: correct dental alignment, need for permanent orthodontic retention in the lower anterior segments, free of occlusal interferences in order to eliminate the influence of trauma Exclusion criteria: not mentioned Setting: Unit of Orthodontics and Paediatric Dentistry, University of Pavia, Italy
Interventions	Two types of lower lingual fixed retainers: Group 1: ⌀ 0.0175 mm multistranded wire  Group 2: fibre‐reinforced composite retainer preimpregnated with Transbond XT Primer (3M Unitek, Monrovia, California, USA)
Outcomes	Survival: numbers (percentage) of total detachment at the end of follow‐up, Kaplan‐Meier survival plots and hazard ratio Patient satisfaction: opinion about the aesthetic result while talking and smiling by means of VAS Time points: every month for 12 months
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Just mentioned "randomly assigned"
Allocation concealment (selection bias)	Unclear risk	Not mentioned
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not mentioned
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	The number of participants is not clear: "34 patients were enroled: 17 with a multistrand wire retainer, while 15 with a polyethylene fiber‐reinforced resin composite"
Selective reporting (reporting bias)	Low risk	No dropouts in the 12‐month follow‐up
Other bias	Unclear risk	Not reported using CONSORT standards