Relationship between friction force and orthodontic force at the leveling stage using a coated wire.
The relationship between orthodontic force and friction produced from an archwire and brackets affects the sliding of the wire in the leveling stage.


OBJECTIVE
The purpose of this study was to evaluate the relationship between force and friction in a small esthetic nickel-titanium (Ni-Ti) wire.


METHODS
Five esthetic wires (three coated and two plated) and two small, plain Ni-Ti wires (0.012 and 0.014 inches) were used. We performed a three-point bending test according to ISO 15841 and the drawing test with a dental arch model designed with upper linguoversion of the lateral incisor in the arch (displacements of 0.5, 1.0, 2.0 and 3.0 mm), and evaluated the relationship between them.


RESULTS
Unloading bending forces of all wires at displacements of less than 1.0 mm were larger than friction forces, but all friction forces at displacements exceeding 2.0 mm were larger than unloading bending forces. The arch likely expands when displacement from the proximal brackets exceeds 1.0 mm. The friction force of a martensite 0.014-inch Ni-Ti wire was significantly greater than those of the other esthetic and austenitic wires.


CONCLUSIONS
A wire with the smallest possible friction force should be used in cases with more than 1.0 mm displacement.
Nihon University School of Dentistry, Department of Orthodontics, Tokyo, Japan.
Masaki
M
Murayama
Nihon University School of Dentistry, Dental Research Center, Department of Orthodontics, Division of Clinical Research, Tokyo, Japan.
Yasuhiro
Y
Namura
Nihon University School of Dentistry, Dental Research Center, Department of Orthodontics, Division of Clinical Research, Tokyo, Japan.
Takahiko
T
Tamura
Nihon University School of Dentistry, Department of Orthodontics, Tokyo, Japan.
Hiroaki
H
Iwai
Nihon University School of Dentistry, Dental Research Center, Department of Orthodontics, Division of Clinical Research, Tokyo, Japan.
Noriyoshi
N
Shimizu
D001732:Bite Force; D003724:Dental Arch; D017276:Friction; D008422:Materials Testing; D008953:Models, Anatomic; D009532:Nickel; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D012016:Reference Values; D015203:Reproducibility of Results; D013499:Surface Properties; D013718:Tensile Strength; D014025:Titanium
C040654:titanium nickelide; D009532:Nickel; D014025:Titanium