To compare the tensile properties of double helical twisting.

21G and 18G stainless steel wires were used. Monostrand, untwisted double strand and manually twisted double helix wires were tested under gradually increasing tension force until the wires break. Data were analyzed by using a computer system to get force-strain curves.

Forces at the break point showed no significant differences between untwisted double strand wires and helically twisted double strand wires. Forces at the yield point deformation were proportionally increased to the degree of helical twisting until the wires were twisted 20 times (piptch number: 24/10 cm) with no more increase after then. Final strain at break point decreased by helical twisting, which means the range of plastic deformation decreased.

By helical twisting, the wires increase in elastic range and decrease in plastic deformation. Therefore, double helix wiring seemed to be a more effective method of fixation compared to the untwisted double strand wires.