Evans 1998.

Methods	Study design: RCT, 3 parallel groups, factorial design Location: Cardiff, Wales, UK Setting: not stated Number of centres: 2 Study period: in 1996 Funding source: Welsh Scheme for the Development of Health and Social Research
Participants	Inclusion criteria: ≤ 18 years; upper and lower fixed appliances required; no previous orthodontic treatment; any initial phase of expansion with a quadhelix had been stabilised for 2 months; any initial phase of active distal molar movement had been stable for 2 months Exclusion criteria: people who may have experienced periodontal disease and hence loss of attachment Number randomised: 56 participants (112 arches, upper/lower 56/56) (age < 18 years) Number evaluated: 51 participants (98 arches, upper/lower 49/49) (47 participants had data for both arches, 2 had data for upper arches and 2 for lower arches)
Interventions	Comparison: multistrand stainless steel vs martensitic NiTi vs different martensitic NiTi Group A (n = 31 arches, upper/lower 14/17): 0155‐inch multistrand stainless steel (Dentaflex, Dentarium) Group B (n = 32 arches, upper/lower 19/13): 016/022‐inch medium force active martensitic NiTi (Titanium Heat Memory Wire, American Orthodontics) Group C (n = 35 arches, upper/lower 16/19): 016/022‐inch graded force, active martensitic NiTi (Bioforce Sentalloy, GAC) Bracket types: A Company Siamese brackets 0.022 Roth prescription in Centre 1 and Orthocare Spectrum I Siamese brackets 0.022 Roth prescription in Centre 2 Operators: 6 operators
Outcomes	Alignment rate: tooth movement measured on LII at 4 and 8 weeks (indirectly) Time to next arch wire (no variance estimates)
Notes	Sample size calculation: "100 dental arches in this trial, in other words 50 subjects (50 upper and 50 lower arches), would provide adequate statistical power (80%) to detect a significant difference in the performance of any two separate arch wires (p < 0.05)." Baseline comparability: not stated Other information: MScD dissertation reported: 1. Centre 1 ‐ A Company Siamese brackets Roth prescription 0.022, Centre 2 ‐ Orthocare Spectrum I Siamese brackets 0.022 Roth prescription; 2. Arch wire allocation was predetermined via a randomised sealed nested envelope technique. Type of ligation based on operator preference, variable and not reported. No further information was obtained from the study authors.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Allocation was predetermined and randomized."
Allocation concealment (selection bias)	Low risk	Quote: "randomised sealed nested envelope technique" from MScD dissertation
Blinding of participants and personnel (performance bias) Patient reported outcomes	Unclear risk	Comment: blinding of participants and personnel not stated
Blinding of outcome assessment (detection bias) Clinician assessed outcomes	Unclear risk	Comment: blinding of outcome assessment not stated
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Comment: 14 arches (12.5%) excluded from analysis
Selective reporting (reporting bias)	Low risk	Comment: planned outcomes reported
Other bias	Unclear risk	Quote: "The allocated arch wire was then ligated by one of six clinicians as fully as possible into the bracket with the clinicians preferred method (usually elastomeric rings)." Comment: unclear risk. MScD dissertation also reported: 1. Centre 1 ‐ A Company Siamese brackets Roth prescription 0.022, Centre 2 ‐ Orthocare Spectrum I Siamese brackets 0.022 Roth prescription. The use of brackets of different types was not randomised. Two centres used different brackets and the sample size of each centre was not stated. The effect of brackets could not be estimated.