Force generation by orthodontic coil springs.
Nickel titanium (NiTi) coil springs are a new development in orthodontics, designed to produce light continuous forces. This study compares the force delivery by NiTi open and closed coil springs during unloading (de-activation) to that provided by comparable stainless steel (SS) springs. Open-coil springs (0.010 x 0.035 inch) were compressed from their initial length of 15 mm to 6 mm and the forces generated with spring recovery recorded. Closed-coil springs (0.009 x 0.035 inch) were distracted from their initial length of 3 mm to 9 mm and the force recorded as the spring recovered. The closed-coil NiTi springs produced light continuous forces of 75-90 g over the distraction range of 6 mm while the open-coil springs produced forces of 55-70 g within the 9 mm compression range. SS springs produced heavier forces, ca. 200 g, for an activation of 1 mm and the generated force increased rapidly as the activation was increased. The findings indicate that NiTi coil springs deliver optimal forces for orthodontic tooth movement over a longer activation range than comparable SS springs.
School of Dentistry, University of Louisville, KY 40292.
J A
JA
von Fraunhofer
P W
PW
Bonds
B E
BE
Johnson
D006801:Humans; D009532:Nickel; D009969:Orthodontic Wires / Q000592:standards*; D013193:Stainless Steel; D014025:Titanium; D014087:Tooth Movement Techniques / Q000295:instrumentation / Q000379:methods*
D013193:Stainless Steel; D009532:Nickel; D014025:Titanium