Evaluation of deflection forces of orthodontic wires with different ligation types

Abstract

The aim of this study was to evaluate deflection forces of orthodontic wires of different alloys engaged into conventional brackets using several ligation types. Stainless steel, conventional superelastic nickel-titanium and thermally activated nickel-titanium archwires tied into conventional brackets by a ring-shaped elastomeric ligature (RSEL), a 8-shaped elastomeric ligature (8SEL) and a metal ligature (ML) were tested. A clinical simulation device was created especially for this study and forces were measured with an Instron Universal Testing Machine. For the testing procedure, the block representing the maxillary right central incisor was moved 0.5 and 1 mm bucco-lingually at a constant speed of 2 mm/min, and the forces released by the wires were recorded, in accordance with the ISO 15841 guidelines. In general, the RSEL showed lighter forces, while 8SEL and ML showed higher values. At the 0.5 mm deflection, the 8SEL presented the greatest force, but at the 1.0 mm deflection the ML had a statistically similar force. Based on our evaluations, to obtain lighter forces, the thermally activated nickel-titanium wire with the RSEL are recommended, while the steel wire with the 8SEL or the ML are recommended when larger forces are desired. The ML exhibited the highest force increase with increased deflections, compared with the elastomeric ligatures.

Evaluation of friction on self-ligating and conventional brackets associated with different types of archwires submitted to sliding mechanics

“…In conventional brackets associated with copper nickel titanium archwires, the friction would be lower due to the smaller area of contact of the ligature with the archwire, and also due to the lower pressure exerted by the elastic ligature on the archwire. These findings corroborated those of studies in which lower pressure exerted by the elastic ligatures were found, making the pressure smoother and diminishing the points of contact of the wire with the internal part of the slot 21 .…”

“…This fact may be explained by the more polished, smoother surface and greater rigidity of this wire, so that in spite of the pressure exerted by the clips of the active self-ligating brackets, the contact surface of this wire would not be increased. In the case of conventional brackets, the elastic ligature would not produce sufficient force to increase the surface of contact at the bracket/archwire interface, corroborating the findings of previous studies in which the composition of the archwire and clip of the bracket were reported 2,11,16,18,19,21 .…”

“…Among the various wires used for making orthodontic arches, stainless steel wires are outstanding as they have a polished surface 14,20 . However, the technological evolution has led to new archwires being used, among them the nickel titanium type with the addition of copper (CuNiTi) 17,21 . The incorporation of copper has resulted in these archwires having more defined thermoactive properties than the superelastic NiTi archwires, therefore, they exert more homogeneous forces throughout the arch, providing faster, more effective movement, in an optimal system of forces, with greater control of tooth movement; they may be used in different orthodontic treatment protocols, as they achieve more biologically compatible results by releasing more physiological force and shortening the time of treatment 2,4,10,[21][22][23] .…”

Is catastrophising associated with pain perception in early phase of orthodontic treatment? A cohort study

“…29 Although some studies reported no correlation between the amount of tooth crowding and pain perception, 4,5,18 this study showed that the increase of 1 mm of tooth crowding represents 1.1 times greater risk of pain. Tooth crowding may deflect the arch, increase the force 30,31 and consequently influence the pain perception.…”

Orthodontic force prediction model of T-loop closing spring based on dynamic resistance model

“…After the orthodontic archwire is put into the orthodontic bracket, the orthodontic force will be generated in the process of its shape restoration. 12 The orthodontic force will move the tooth to the target position, thus completing the space closure. 13,14 The magnitude of the orthodontic force is affected by not only the material characteristics of the archwire but also the shape parameters and the clearance distance.…”