Changes in frictional resistance between stainless steel bracket and various orthodontic wires according to a change in moment

Jeong, Hye Jin; Lim, Sung Hoon; Kim, Kwang Won

Abstract

OBJECTIVE
The purpose of this study was to compare changes in frictional resistance between the bracket and wire under dry and wet conditions according to a change in moment.
METHODS
A stainless steel bracket of 0.022" x 0.028" slot, and 0.019" x 0.025" stainless steel, beta-titanium, and nickel-titanium wires were used. A 10 mm length lever was attached to the test (sliding) brackets to generate a moment. The experimental model was designed to allow tipping until contacts were established between the wire and the mesiodistal edges of the bracket slot. The moment was generated by suspending a 100 g or 200 g weight on the end of the lever. The moments applied were 1000 g.mm (100 g x 10 mm) and 2000 g.mm (200 g x 10 mm). The test brackets were ligated with elastomeric ligature for a constant ligation force and the fixed brackets were ligated with stainless steel ligature. Brackets were moved along the wire by means of an universal testing machine, and maximum frictional resistances were recorded.
RESULTS
Stainless steel wire showed least frictional resistance and there was no significant difference between beta-titanium and nickel-titanium except at 2000 g.mm moment in wet conditions. Frictional resistance of all wires increased as the moment increased from 1000 g.mm to 2000 g.mm. Under wet conditions, the frictional resistance of stainless steel wires increased in both 1000 g.mm and 2000 g.mm moment conditions, but frictional resistance of nickel-titanium and beta-titanium increased only in 2000 g.mm conditions.
CONCLUSION
These results indicated that various conditions influence on frictional resistance. Therefore, laboratory studies of frictional resistance should simulate clinical situation.