title: A randomized clinical trial investigating pain associated with superelastic nickel-titanium and multistranded stainless steel archwires during the initial leveling and aligning phase of orthodontic treatment.
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.
  
  
  METHODS
  A double-blind two-arm parallel design stratified randomized clinical trial.
  
  
  METHODS
  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 value = 2.65, degrees of freedom (df) = 92.6; P = 0.1071]. However, compared to multistranded stainless steel wires, pain in subjects with superelastic nickel-titanium archwires was significantly greater at 12 h (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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: S. S. Sandhu, Department of Orthodontics and Dentofacial Orthopedics, Genesis Institute of Dental Sciences and Research, Ferozepur, Punjab, India. drsatpalsandhu@yahoo.co.in.
authors.forename: Satpal Singh
authors.initials: SS
authors.lastname: Sandhu
authors.forename: Jasleen
authors.initials: J
authors.lastname: Sandhu
mesh_terms: D000293:Adolescent; D002648:Child; D003722:Dental Alloys / Q000737:chemistry*; D004311:Double-Blind Method; D004548:Elasticity; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008310:Malocclusion / Q000628:therapy; D009532:Nickel / Q000737:chemistry*; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires / Q000009:adverse effects; D010146:Pain / Q000209:etiology*; D010147:Pain Measurement; D013193:Stainless Steel / Q000737:chemistry*; D013499:Surface Properties; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*; D014087:Tooth Movement Techniques / Q000009:adverse effects / Q000295:instrumentation*; D064232:Visual Analog Scale
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium
keywords: Orthodontic pain; alignment; initial archwires