Measurements of the torque moment in various archwire-bracket-ligation combinations

Abstract

The torque moment generated by third-order bends is important for tooth movement. The purpose of this study was to measure the torque moment that can be delivered by various archwire and bracket combinations at the targeted tooth. Stainless steel (SS) upper brackets with 0.018 and 0.022 inch slots, two sizes of nickel-titanium (Ni-Ti) alloy wires, and three sizes of SS wires for each bracket were used. The wire was ligated with elastics or wire. The torque moment delivered by the various archwire-bracket-ligation combinations was measured using a torque gauge. Statistical analysis was undertaken using analysis of variance (multiple comparison tests and post hoc using Tukey's honestly significant difference test. The torque moment increased as the degree of torque and wire size increased. There was no significant difference in torque moment between the SS and Ni-Ti wires at lower or higher than 40 degrees torque. The torque moment with wire ligation was significantly larger than that with elastic ligation with 0.016 × 0.022 and 0.017 × 0.025 inch Ni-Ti wires in the 0.018 inch slot brackets and the 0.017 × 0.025 and 0.019 × 0.025 inch SS and Ni-Ti wires in the 0.022 inch slot brackets. However, there was no significant difference in torque moment between either ligation method when using the full slot size wires.

Evaluation of torque moment in a novel elastic bendable orthodontic wire

“…The moment with wire ligation was significantly larger than those with elastic ligation at all applied torques in all wire sizes and materials. These results are consistent with previous studies on this issue [15][16][17] . Except for the ligation methods, several factors associated with torque moment are suggested, i.e.…”

“…Except for the ligation methods, several factors associated with torque moment are suggested, i.e. wire stiffness, play between the wire and bracket, bracket design, bracket material and so on [15][16][17][18][19][20] . In the present study, large size wires (0.019×0.025 inch wire) showed larger torque moment than small size wires (0.017×0.025 inch wire), because of the play.…”

“…The average upper incisor root length is 13.0 mm 21) . Thus, it was hypothesized that the optimum torque was approximately 0.01-0.02 Nm, which was basically calculated by data from previous studies [12][13][14][15]22,23) . Concerning the active moment of optimum torques of the Ti-Nb wires, the hypothesized optimum torques were provided by twisting the 0.017×0.025 inch wires with 15 to 35 degrees with wire ligation and 20 to 40 degrees with elastic module ligation.…”

“…According to the previous study, the torque moments of the three alloy wires were measured as mentioned below 15) . The measuring apparatus consisted of a torque transducer connected to a torque gauge (Kyowa Electronic Instruments Co., Tokyo, Japan; Fig.…”

“…Therefore, until the slot fills the wire, a considerable percentage of the torque built into the bracket is lost because of the play between the wire and bracket slot 12) . There are a number of reports in the literature in which the theoretical and/or measured torque moments between wire and bracket have been calculated [13][14][15][16][17][18][19][20] . Although there may be some discrepancies between in vitro and in vivo conditions, these studies could help in understanding the amount of third-order bends for wire-bracket-ligation combinations.…”