In vitro evaluation of frictional forces generated by three different ligation methods

The aim of this in vitro study was to compare the frictional forces produced by a passive self-ligating bracket (SLB) and two types of elastomeric ligatures (conventional elastomeric ligature, CEL, and unconventional elastomeric ligatures, UEL) on a conventional bracket (CB) used with two types of wires (.014” super elastic nickel titanium wire and .019”X.025” stainless steel wire). Resistance to sliding of the bracket/wire/ligature systems was measured with an experimental model mounted on the crosshead of an Instron testing machine with a 10 N load cell. Each sample was tested consecutively 10 times under dry state. Frictional forces close to 0g were recorded in all tests both with SLB and with UEL on CB with both wire types. Resistance to sliding increased significantly (87-177g) (p<0.05) when CEL on CB was used with both wires. UELs may represent a valid alternative to passive SLBs for low-friction biomechanics.