title: Influence of fluoride-containing acidic artificial saliva on the mechanical properties of Nickel-Titanium orthodontics wires.
abstract: OBJECTIVE
  This study aimed to investigate the influence of fluoride and an acidic environment on the mechanical properties of NiTi orthodontic wires (NiTiW) in artificial saliva.
  
  
  METHODS
  A prospective laboratory investigation.
  
  
  METHODS
  Department of Stomatology, First Affiliated Hospital, Zhejiang University, Hangzhou, China.
  
  
  METHODS
  Commercial, round 0.016-inch NiTiW were immersed in 0% or 0.05% Natrium-Fluoride-containing artificial saliva at a pH of 4 or 6 for one or three days, respectively. NiTiW were examined with a three-point bending test, Vickers' microhardness tests and surface morphology observation (SEM).
  
  
  RESULTS
  A pH of 4 increased microhardness and decreased the three-point bending strength significantly (P≤0.05), whereas immersion time and fluoride concentration had no significant influence on the microhardness or on the three-point bending strength (P>0.05). When examining the test group NiTiWs after three days of immersion at a pH of 4 the SEM revealed a rough surface morphology, a damaged oxide layer and signs of corrosion.
  
  
  CONCLUSIONS
  The most influential factor for decreasing the unloading force and increasing the hardness seems to be the pH value, whereas immersion time and NaF addition do not have a major influence.
authors: Department of Stomatology, First Affiliated Hospital, Hangzhou, China.
authors: Jun
authors: J
authors: Lin
authors: Shujuan
authors: S
authors: Han
authors: Jiajun
authors: J
authors: Zhu
authors: Xiaoxiang
authors: X
authors: Wang
authors: Yuan
authors: Y
authors: Chen
authors: Oliver
authors: O
authors: Vollrath
authors: Huiming
authors: H
authors: Wang
authors: Christian
authors: C
authors: Mehl
mesh_terms: D000143:Acids / Q000737:chemistry; D002327:Cariostatic Agents / Q000737:chemistry*; D003343:Corrosion; D003722:Dental Alloys / Q000737:chemistry*; D006244:Hardness; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D009532:Nickel / Q000737:chemistry*; D009969:Orthodontic Wires; D010087:Oxides / Q000737:chemistry; D018583:Pliability; D011446:Prospective Studies; D012464:Saliva, Artificial / Q000737:chemistry*; D012969:Sodium Fluoride / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*
chemical_list: D000143:Acids; D002327:Cariostatic Agents; D003722:Dental Alloys; D010087:Oxides; D012464:Saliva, Artificial; C040654:titanium nickelide; D009532:Nickel; D012969:Sodium Fluoride; D014025:Titanium