title: Friction between different wire bracket combinations in artificial saliva--an in vitro evaluation.
abstract: OBJECTIVE
  The objective this work was to assess the friction coefficient between brackets and wires of different materials under conditions simulating the oral environment.
  
  
  METHODS
  Stainless steel (SS) and titanium-molybdenum alloy (TMA) wires of 0.019x0.025-in diameter (American Orthodontics) and polycarbonate bracket (American Orthodontics), ceramic bracket (American Orthodontics), and metal bracket (3M Unitek) with slots of 0.022x0.030-in were used. The friction coefficient was assessed by means of mechanical traction with the system immersed in artificial saliva. The mean roughness of both wire surface and bracket slots was evaluated by using a surface profilometer.
  
  
  RESULTS
  The system using TMA wire and polycarbonate bracket had the highest roughness (p<0.05). SS wire with ceramic bracket had the highest friction coefficient, whereas the use of metallic bracket yielded the lowest (p<0.05). However, it was observed a statistically significant difference in the system using TMA wire and ceramic bracket compared to that using TMA wire and polycarbonate bracket (p=0.038).
  
  
  CONCLUSIONS
  Ceramic brackets in association with SS wire should be judiciously used, since this system showed a high friction coefficient.
authors: Dental School, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors: Tatiana Kelly da Silva
authors: TK
authors: Fidalgo
authors: Matheus Melo
authors: MM
authors: Pithon
authors: José Vinicius Bolognesi
authors: JV
authors: Maciel
authors: Ana Maria
authors: AM
authors: Bolognese
mesh_terms: D000704:Analysis of Variance; D017276:Friction; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D012464:Saliva, Artificial; D013193:Stainless Steel / Q000737:chemistry*; D013499:Surface Properties; D013718:Tensile Strength; D014025:Titanium / Q000737:chemistry*
chemical_list: D012464:Saliva, Artificial; D013193:Stainless Steel; D014025:Titanium