title: Effect of ion-implantation on surface characteristics of nickel titanium and titanium molybdenum alloy arch wires.
abstract: OBJECTIVE
  To evaluate the changes in surface roughness and frictional features of 'ion-implanted nickel titanium (NiTi) and titanium molybdenum alloy (TMA) arch wires' from its conventional types in an in-vitro laboratory set up.
  
  
  METHODS
  'Ion-implanted NiTi and low friction TMA arch wires' were assessed for surface roughness with scanning electron microscopy (SEM) and 3 dimensional (3D) optical profilometry. Frictional forces were studied in a universal testing machine. Surface roughness of arch wires were determined as Root Mean Square (RMS) values in nanometers and Frictional Forces (FF) in grams.
  
  
  METHODS
  Mean values of RMS and FF were compared by Student's 't' test and one way analysis of variance (ANOVA).
  
  
  RESULTS
  SEM images showed a smooth topography for ion-implanted versions. 3D optical profilometry demonstrated reduction of RMS values by 58.43% for ion-implanted NiTi (795.95 to 330.87 nm) and 48.90% for TMA groups (463.28 to 236.35 nm) from controls. Nonetheless, the corresponding decrease in FF was only 29.18% for NiTi and 22.04% for TMA, suggesting partial correction of surface roughness and disproportionate reduction in frictional forces with ion-implantation. Though the reductions were highly significant at P < 0.001, relations between surface roughness and frictional forces remained non conclusive even after ion-implantation.
  
  
  CONCLUSIONS
  The study proved that ion-implantation can significantly reduce the surface roughness of NiTi and TMA wires but could not make a similar reduction in frictional forces. This can be attributed to the inherent differences in stiffness and surface reactivity of NiTi and TMA wires when used in combination with stainless steel brackets, which needs further investigations.
authors.affiliation: Department of Dental Research and Implantology, Institute of Nuclear Medicine and Allied Sciences (INMAS), Defence Research and Development Organization (DRDO), Ministry of Defence, Govt of India, Timarpur, Delhi, India.
authors.forename: Manu
authors.initials: M
authors.lastname: Krishnan
authors.forename: Seema
authors.initials: S
authors.lastname: Saraswathy
authors.forename: Kalathil
authors.initials: K
authors.lastname: Sukumaran
authors.forename: Kurian Mathew
authors.initials: KM
authors.lastname: Abraham
mesh_terms: D000497:Alloys / Q000737:chemistry*; D007477:Ions; D009532:Nickel / Q000737:chemistry*; D009969:Orthodontic Wires; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D000497:Alloys; D007477:Ions; C525450:titanium molybdenum alloy; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium