Pandis 2010a.

Study characteristics
Methods	Setting: Corfu, Greece, private practice of study author Design: parallel (2 arms) No. of centres: 1 Study duration: 175 days
Participants	Inclusion criteria: "non‐extraction treatment in both arches, eruption of all maxillary teeth, no spaces in the maxillary arch, no high canines, maxillary irregularity index greater than 4 mm, and no therapeutic intervention planned involving intermaxillary or other intraoral or extraoral appliances including elastics, maxillary expansion appliances, or headgear". Exclusion criteria: not reported Participant sampling: N = 70 selected Group 1 (n = 35): 60% female, 40% male (mean age of 13.8 ± 1.8 years) Group 2 (n = 35): 57% female, 43% male (mean age of 13.8 ± 1.7 years) Sex: 58.6% female, 41.4% male Dropouts: 4 (2 per group)
Interventions	Orthodontic intervention: fixed appliances and auxiliaries Active versus passive self‐ligating brackets
Outcomes	Crowding, time to alignment
Notes	Funding source: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Adequate method of randomisation "Randomization was accomplished by generating random permuted blocks of variable size; this ensured equal patient distribution between the 2 trial arms."
Allocation concealment (selection bias)	Low risk	Adequate method of allocation concealment "Numbered, opaque, sealed envelopes were prepared before the trial containing the treatment allocation card. After patient selection, the secretary of the practice was responsible for opening the next envelope in sequence."
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not possible to blind participants and personnel due to the different interventions used
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Unclear if assessor was blinded "Measurements were made twice on the initial casts by the first author with a digital caliper (Digimatic NTD12‐6’’C, Mitutoyo, Tokyo, Japan)."
Incomplete outcome data (attrition bias) All outcomes	Low risk	4 dropouts (2 per group) = 6%
Selective reporting (reporting bias)	Low risk	All outcomes reported
Other bias	Unclear risk	Single centre, private practice; per‐protocol analysis