Influence of bracket-slot design on the forces released by superelastic nickel-titanium alignment wires in different deflection configurations.
OBJECTIVE
To evaluate how different bracket-slot design characteristics affect the forces released by superelastic nickel-titanium (NiTi) alignment wires at different amounts of wire deflection.


METHODS
A three-bracket bending and a classic-three point bending testing apparatus were used to investigate the load-deflection properties of one superelastic 0.014-inch NiTi alignment wire in different experimental conditions. The selected NiTi archwire was tested in association with three bracket systems: (1) conventional twin brackets with a 0.018-inch slot, (2) a self-ligating bracket with a 0.018-inch slot, and (3) a self-ligating bracket with a 0.022-inch slot. Wire specimens were deflected at 2 mm and 4 mm.


RESULTS
Use of a 0.018-inch slot bracket system, in comparison with use of a 0.022-inch system, increases the force exerted by the superelastic NiTi wires at a 2-mm deflection. Use of a self-ligating bracket system increases the force released by NiTi wires in comparison with the conventional ligated bracket system. NiTi wires deflected to a different maximum deflection (2 mm and 4 mm) release different forces at the same unloading data point (1.5 mm).


CONCLUSIONS
Bracket design, type of experimental test, and amount of wire deflection significantly affected the amount of forces released by superelastic NiTi wires (P<.05). This phenomenon offers clinicians the possibility to manipulate the wire's load during alignment.
a  Assistant Professor, Department of Scienze Sperimentali Medico Chirurgiche ed Odontostomatologiche, Section of Orthodontics, School of Dentistry, University of Messina, Messina, Italy.
Riccardo
R
Nucera
Elda
E
Gatto
Chiara
C
Borsellino
Pasquale
P
Aceto
Francesca
F
Fabiano
Giovanni
G
Matarese
Letizia
L
Perillo
Giancarlo
G
Cordasco
D003722:Dental Alloys / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D004548:Elasticity; D020724:Elastomers / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry*; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D012399:Rotation; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D014087:Tooth Movement Techniques / Q000295:instrumentation; D019415:Torque
D003722:Dental Alloys; D020724:Elastomers; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium