title: Do the NiTi low and constant force levels remain stable in vivo?
abstract: OBJECTIVE
  The aim was to evaluate the alteration of the deactivation forces of the most commonly used nickel-titanium wires under long-lasting oral cavity environmental influence.
  
  
  METHODS
  Randomized in vitro and in vivo trials of 540 pieces of orthodontic archwires, NeoSentalloy®, Copper NiTi® 35°C and Titanol Superelastic(®), round (0.016 inch), and rectangular (0.016 × 0.022 inch), were carried out. Randomization and blinding was achieved with 12-colour system that ensured encoding of key information on the tested specimens. Each of 270 patients (females, 18-20 years old, in the finishing stage of orthodontic treatment) received the piece of NiTi wire ligated piggyback, for a period of 4-6 weeks. Eventually, all samples were subjected to a three-point bending test. Data were statistically analysed at a 5 per cent significance level.
  
  
  RESULTS
  In the group of the round used wires, when compared with the new ones, the deactivation force (F dav) values increased significantly for Titanol Superelastic®; the NeoSentalloy® and Copper NiTi® 35°C wires did not change their values of F dav. In the group of rectangular wires, F dav decreased for Titanol Superelastic®, but increased for NeoSentalloy® wires. The F dav values of the Copper NiTi® 35°C used wires practically did not change, but a remarkable increase of the standard deviation was noted.
  
  
  CONCLUSIONS
  No calculations concerning effectiveness of in vivo aligning of analysed wires were made.
  
  
  CONCLUSIONS
  For the purpose of a 4-6-week aligning stage, round NeoSentalloy® with a diameter of 0.016 inches seems to be the wire of choice because of the low level of F dav.
authors.affiliation: Departments of *Dentofacial Orthopedics and Orthodontics and michal.sarul@gmail.com.
authors.forename: Michał
authors.initials: M
authors.lastname: Sarul
authors.affiliation: Departments of *Dentofacial Orthopedics and Orthodontics and.
authors.forename: Beata
authors.initials: B
authors.lastname: Kawala
authors.affiliation: Restorative Dentistry, Wroclaw Medical University, Wroclaw, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Kawala
authors.affiliation: Departments of *Dentofacial Orthopedics and Orthodontics and.
authors.forename: Joanna
authors.initials: J
authors.lastname: Antoszewska-Smith
mesh_terms: D000293:Adolescent; D003300:Copper / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry*; D004548:Elasticity; D005260:Female; D006801:Humans; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry*; D016382:Orthodontic Appliance Design; D009969:Orthodontic Wires / Q000145:classification; D018583:Pliability; D011897:Random Allocation; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D055815:Young Adult
chemical_list: C415948:Copper NiTi; D003722:Dental Alloys; C040654:titanium nickelide; D003300:Copper; D009532:Nickel; D014025:Titanium