title: The effect of different combinations of tip and torque on archwire/bracket friction.
abstract: The aim of this laboratory-based study was to investigate the effects of different combinations of tip and torque upon friction between an orthodontic bracket and archwire using a specially made jig. Victory Twin Series upper premolar brackets (3M Unitek) were mounted on a jig, which allowed tip and torque values in the slot to be varied without altering the centre of rotation. The jig was mounted on an Instron machine and resistance to sliding (RS) was measured as brackets were drawn along rectangular 0.019 x 0.025 inch wires at various combinations of tip and torque from 0 to 12 degrees. Five tests were carried out for each combination. The results were analysed using analysis of variance and Tukey's pairwise comparisons by means of the Minitab statistical package. Increasing tip and torque produced increases in sliding resistance from 1.35 to 19.08 N. Both tip and torque had significant effects on friction. RS was significantly increased by tip and torque separately (P < 0.001) and in combination (P < 0.001), although tip was the more powerful influence.
authors.affiliation: School of Dentistry, University of Birmingham, UK.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Hamdan
authors.forename: Peter
authors.initials: P
authors.lastname: Rock
mesh_terms: D003722:Dental Alloys; D003799:Dental Stress Analysis / Q000295:instrumentation*; D017276:Friction; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D013193:Stainless Steel; D019415:Torque
chemical_list: D003722:Dental Alloys; D013193:Stainless Steel