Orthodontic buccal tooth movement by nickel-free titanium-based shape memory and superelastic alloy wire.
OBJECTIVE
To examine the mechanical properties and the usefulness of titanium-niobium-aluminum (Ti-Nb-Al) wire in orthodontic tooth movement as compared with nickel-titanium (Ni-Ti) wire.


METHODS
The load deflection of expansion springs was gauged with an original jig. The gradient of the superelastic region was measured during the unloading process. Expansion springs comprising the two types of alloy wires were applied to upper first molars of rats. The distance between the first molars was measured with micrometer calipers.


RESULTS
The force magnitude of the Ti-Nb-Al expansion spring was lower than that of the Ni-Ti expansion spring over the entire deflection range. The initial force magnitude and the gradient in the superelastic region of the Ti-Nb-Al expansion springs were half those of the Ni-Ti expansion springs. Thus, Ti-Nb-Al expansion springs generated lighter and more continuous force. Tooth movement in the Ni-Ti group proceeded in a stepwise fashion. On the other hand, tooth movement in the Ti-Nb-Al group showed relatively smooth and continuous progression. At 17 days after insertion of expansion springs, there were no significant differences between the Ti-Nb-Al and Ni-Ti groups in the amount of tooth movement.


CONCLUSIONS
These results indicate that Ti-Nb-Al wire has excellent mechanical properties for smooth, continuous tooth movement and suggest that Ti-Nb-Al wire may be used as a practical nickel-free shape memory and superelastic alloy wire for orthodontic treatment as a substitute for Ni-Ti wire.
Suzuki
Akihiro
A
Division of Orthodontics and Dentofacial Orthopedics, Tohoku University Graduate School of Dentistry, Sendai, Miyagi, Japan.
Kanetaka
Hiroyasu
H
Shimizu
Yoshinaka
Y
Tomizuka
Ryo
R
Hosoda
Hideki
H
Miyazaki
Shuichi
S
Okuno
Osamu
O
Igarashi
Kaoru
K
Mitani
Hideo
H
D000818:Animals; D019245:Compressive Strength; D003722:Dental Alloys; D003799:Dental Stress Analysis; D004548:Elasticity; D008297:Male; D008422:Materials Testing; D009532:Nickel; D016382:Orthodontic Appliance Design; D009969:Orthodontic Wires; D051381:Rats; D017208:Rats, Wistar; D018709:Statistics, Nonparametric; D014025:Titanium; D014087:Tooth Movement Techniques / Q000295:instrumentation*
D003722:Dental Alloys; C516027:titanium-niobium-aluminum alloy; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium