O'Brien 1990.

Methods	Study design: RCT, 2 parallel groups Location: Manchester UK Setting: University Dental Hospital of Manchester Number of centres: 1 Study period: not stated Funding source: "the assistance of Thomas Bolton & Johnson Limited, Stoke‐on‐Trent, England, for supplying the archwires"
Participants	Inclusion criteria: patients attending university dental hospital clinic for routine Edgewise fixed appliance therapy Exclusion criteria: not stated Number randomised: 40 participants (40 arches, upper/lower 40/0) (group A: mean age 13.4 ± 3.12 years, aged from 11.5‐17.5 years; group B: male/female: 9/11, mean age 12.95 ± 3.2 years, aged from 11‐16.5 years) Number evaluated: not stated
Interventions	Comparison: conventional NiTi vs superelastic NiTi Group A (n = 20, upper/lower 20/0): 0.016‐inch conventional work hardened NiTi, Nitinol (Unitek Corp) Group B (n = 20, upper/lower 20/0): 0.016‐inch superelastic NiTi, Titanol (Forestadent) They were all fitted with identical edgewise brackets. The archwire was tied with ligatures into the brackets, the operator attempting to achieve complete engagement where clinically possible. Operators: not stated
Outcomes	Alignment rate: tooth movement till next arch wire (indirectly)
Notes	Sample size calculation: not stated Baseline comparability: for initial tooth displacement, there was no significant difference between the two groups (P > 0.05). Other information: the following completed data were acquired by personal communication: 1) participants were followed to the second data collection stage at 35 days; 2) slot size of the bracket was "probably 0.018 inch".
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "The sequence was generated by a random number generator" from personal email
Allocation concealment (selection bias)	Low risk	Quote: "We put the arch wires into envelopes which were in a box on the clinic. The operator then took the next sequential arch wire" from personal email
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	Low risk	Quote: "When I recorded the tooth movement from the study casts, I did not know which group the patients had been allocated, I was therefore blinded" from personal email
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Comment: number of participants included in the evaluation of outcomes not stated
Selective reporting (reporting bias)	High risk	Quote: "We attempted to record pain data but this was not sufficiently reliable for analysis" from personal email Comments: not all prespecified primary outcomes reported
Other bias	Low risk	Comment: no other sources of bias identified