ABSTRACT
OBJECTIVE: To investigate and compare the effects of superelastic nickel-titanium and multistranded stainless steel archwires on pain during the initial phase of orthodontic treatment. DESIGN: A double-blind two-arm parallel design stratified randomized clinical trial. SETTING: A single centre in India between December 2010 and June 2012. A total of 96 participants (48 male and 48 females; 14.1±2.1 years old) were randomized (stratified on age, sex and initial crowding) to superelastic nickel-titanium or multistranded stainless steel archwire groups using a computer-generated allocation sequence. METHODS: We compared 0.016-inch superelastic nickel-titanium and 0.0175-inch multistranded stainless steel wires in 0.022-inch slot (Roth prescription) preadjusted edgewise appliances. The follow-up period was 14 days. Outcome was assessed with a visual analogue scale at baseline and 32 pre-specified follow-up points. Data was analyzed using mixed-effects model analysis. RESULTS: One participant was lost to follow up and 10 were excluded from the analysis due to bond failure or incomplete questionnaire answers. Ultimately, 85 participants (42 males and 43 females; 14.1±2.0 years old) were analysed for the final results. No statistically significant difference was found for overall pain [F valueâ=â2.65, degrees of freedom (df)â=â92.6; Pâ=â0.1071]. However, compared to multistranded stainless steel wires, pain in subjects with superelastic nickel-titanium archwires was significantly greater at 12 h (tâ=â2.34; Pâ=â0.0193), as well as at day 1 in the morning (tâ=â2.21, Pâ=â0.0273), afternoon (tâ=â2.11, Pâ=â0.0346) and at bedtime (tâ=â2.03, Pâ=â0.042). CONCLUSION: For overall pain, there was no statistically significant difference between the two wires. However, subjects with superelastic nickel-titanium archwires had a significantly higher pain at peak level.
