O'Brien 1990.

Study characteristics
Methods	Setting: Manchester, UK Design: parallel (2 arms) No. of centres: 1 Study duration: up to 37 days
Participants	Inclusion criteria: "...patients who were attending for routine Edgewise fixed appliance therapy..." Exclusion criteria: not reported Orthodontic intervention: 0.016" super‐elastic titinol or 0.016" nitinol archwire; all fitted with identical edgewise brackets Participant sampling: N = 40 selected Group 1 (n = 20): 11 female, 9 male (mean age of 12.95 ± 3.2 years) Group 2 (n = 20): sex of group not reported (mean age of 13.4 ± 3.12 years) Sex: overall sex across both groups not reported Dropouts: none
Interventions	Orthodontic intervention: fixed appliances and auxiliaries Nitinol versus titinol archwires
Outcomes	Crowding
Notes	Funding source: “Thomas Bolton & Johnson Limited, Stoke‐on‐Trent, England, for supplying the archwires.”
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Inadequate information on how randomisation was carried out "Forty patients who were attending for routine Edgewise fixed appliance therapy were randomly allocated".
Allocation concealment (selection bias)	Unclear risk	Unclear if allocation sequence concealed from those assigning patients to participant groups
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
Incomplete outcome data (attrition bias) All outcomes	Low risk	No dropouts
Selective reporting (reporting bias)	Unclear risk	Only contact point movement reported; final contact point displacement not reported "Initial contact point displacement measured and contact point movement following archwire placement in mm."
Other bias	Unclear risk	No sample size calculation