Sandhu 2013.

Study characteristics
Methods	Setting: single centre in India Design: parallel (2 arms) No. of centres: 1 Study duration: December 2010‐June 2012
Participants	Inclusion criteria: "(1) 11‐ to ‐17‐year‐old male and female who required fixed orthodontic treatment; (2) moderate‐to‐severe crowding (4–9 mm) in the mandibular anterior segment that was not severe enough to prevent bracket engagement, patients with severe crowding related to one or two teeth (such as blocked out lateral incisors) were not included; (3) eruption of all mandibular anterior teeth; (4) no history of medical problems/medication that could influence pain perception; and (5) informed and witnessed consent from the minor participant and their parent/guardian". Exclusion criteria: "(1) presence of a severe deep bite that could affect bracket placement on the mandibular anterior teeth; (2) malocclusion correction required treatment procedures other than continuous arch wire mechanics; (3) participants taking pain medications for chronic pain; (4) participants with a positive history of dental pain or pain in the orofacial region; (5) a medical condition that precluded the use of a fixed orthodontic appliance (e.g. allergy to nickel, recent history of epileptic seizure or physician’s consent could not be obtained, etc.)" Participant sampling: N = 96 selected Group 1: 21 female, 21 male (mean age of 14.2 ± 1.9 years) Group 2: 22 female, 21 male (mean age of 13.9 ± 2.0 years) Sex: 43 female, 42 male Dropouts: "One participant was lost to follow up and 10 were excluded from the analysis due to bond failure or incomplete questionnaire answers".
Interventions	Orthodontic intervention: fixed appliances and auxiliaries Nickel‐titanium versus multistranded stainless steel archwires
Outcomes	Harms (pain perception)
Notes	"No statistically significant difference was found for overall pain [F value = 2.65, degrees of freedom (df) = 92.6; P = 0.1071]" "Compared to multistranded stainless steel wires, pain in subjects with superelastic nickel–titanium archwires was significantly greater at 12h (t = 2.34; P = 0.0193), as well as at day 1 in the morning (t = 2.21; P = 0.0273), afternoon (t = 2.11; P = 0.0346) and at bedtime (t = 2.03; P = 0.042)" "Subjects with superelastic nickel–titanium archwires had a significantly higher pain at peak level"
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Adequate method of randomisation "The randomization schedule was prepared by using ralloc procedure (Stata/SE 10.0 software) to enrol 96 participants into superelastic nickel titanium and multi‐ stranded stainless steel groups using stratified block (size 4) randomization."
Allocation concealment (selection bias)	Low risk	Adequate method of allocation concealment "A statistician generated the random allocation sequence, and the dental assistant helped enrol and conceal participant allocation using the opaque sealed envelope method."
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants blinded, however not possible to blind personnel due to the different interventions
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Adequate blinding of assessors "The VAS score was measured by trained dental assistants (blinded to the study) using a manual 0.1‐ mm calibrated Vernier caliper (manual type)."
Incomplete outcome data (attrition bias) All outcomes	Low risk	Dropouts reported and sample size calculation completed "One participant was lost to follow up and 10 were excluded from the analysis due to bond failure or incomplete questionnaire answers."
Selective reporting (reporting bias)	Low risk	All outcomes reported
Other bias	Low risk	None identified