title: Comparison of friction force between corroded and noncorroded titanium nitride plating of metal brackets.
abstract: BACKGROUND
  Titanium nitride (TiN) plating is a method to prevent metal corrosion and can increase the surface smoothness. The purpose of this study was to evaluate the friction forces between the orthodontic bracket, with or without TiN plating, and stainless steel wire after it was corroded in fluoride-containing solution.
  
  
  METHODS
  In total, 540 metal brackets were divided into a control group and a TiN-coated experimental group. The electrochemical corrosion was performed in artificial saliva with 1.23% acidulated phosphate fluoride (APF) as the electrolytes. Static and kinetic friction were measured by an EZ-test machine (Shimadazu, Tokyo, Japan) with a crosshead speed of 10 mm per minute over a 5-mm stretch of stainless steel archwire. The data were analyzed by using unpaired t test and analysis of variance (ANOVA).
  
  
  RESULTS
  Both the control and TiN-coated groups' corrosion potential was higher with 1.23% APF solution than with artificial solution (P <0.05). In brackets without corrosion, both the static and kinetic friction force between the control and TiN-coated brackets groups showed a statistically significant difference (P <0.05). In brackets with corrosion, the control group showed no statistical difference on kinetic or static friction. The TiN-coated brackets showed a statistical difference (P <0.05) on kinetic and static friction in different solutions.
  
  
  CONCLUSIONS
  TiN-coated metal brackets, with corrosion or without corrosion, cannot reduce the frictional force.
authors.affiliation: Institute of Oral Biology and Biomaterial, College of Oral Medicine, Chung Shan Medical University, Taichung, Taiwan, ROC.
authors.forename: Chia-Tze
authors.initials: CT
authors.lastname: Kao
authors.forename: Jia-Uei
authors.initials: JU
authors.lastname: Guo
authors.forename: Tsui-Hsien
authors.initials: TH
authors.lastname: Huang
mesh_terms: D000149:Acidulated Phosphate Fluoride / Q000737:chemistry; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D003343:Corrosion; D003722:Dental Alloys / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D055664:Electrochemical Techniques; D004595:Electroplating; D017276:Friction; D006801:Humans; D008422:Materials Testing; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D012464:Saliva, Artificial / Q000737:chemistry; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D020099:Coated Materials, Biocompatible; D003722:Dental Alloys; D012464:Saliva, Artificial; D013193:Stainless Steel; D000149:Acidulated Phosphate Fluoride; C041500:titanium nitride; D014025:Titanium