title: Relationship between Af temperature and load changes in Ni-Ti orthodontic wire under different thermomechanical conditions.
abstract: Simple three point bending tests were performed on Ni-Ti wires with three different Af points (1 degree C, 13 degrees C and 34 degrees C) to clarify the relationship between Af temperature and load changes under constant deformation. Each wire was deformed at 37 degrees C and then thermal changes were imposed by temperatures of 2 degrees C or 60 degrees C. The load changes with thermal changes from 37 degrees C to 2 degrees C or 60 degrees C showed the same tendency on the wires with different Af points: In the loading stage, the load became lower than the initial level at 37 degrees C and in the unloading stage, the load became higher than the initial load. The largest load change in the unloading stage was measured with the 13 degrees C Af point wire. Care must be taken when handling Ni-Ti wire with an Af point of less than 1 degree C in order to prevent it from reaching the limit of critical stress of slip deformation when the temperature in the mouth rises to above 40 degrees C.
authors.affiliation: Department of Dental Materials Science, School of Dentistry, Health Sciences University of Hokkaido, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Kawashima
authors.forename: H
authors.initials: H
authors.lastname: Ohno
authors.forename: R
authors.initials: R
authors.lastname: Sachdeva
mesh_terms: D019245:Compressive Strength; D003722:Dental Alloys / Q000737:chemistry*; D004055:Differential Thermal Analysis; D006358:Hot Temperature; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry*; D009969:Orthodontic Wires; D018583:Pliability; D013314:Stress, Mechanical; D013718:Tensile Strength; D014025:Titanium / Q000737:chemistry*
chemical_list: D003722:Dental Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium