Stiffness comparison of mushroom and straight SS and TMA lingual archwires

Abstract

BackgroundThe aim of this study is to investigate the relative stiffness of straight and mushroom lingual archwires of different diameters, cross sections and alloys, plotting their load/deflection graphs and using a modified three-point bending test.MethodsFujita’s mushroom archwires and straight lingual archwires of different diameters, cross sections and alloys were derived by a virtual set-up of an equal malocclusion and were cut at their straight distal portion. These distal portions were tested using a modified three-point bending test by an Instron 4467 dynamometer and the forces, were exerted at 1-mm deflection and were compared on each resulting load/deflection curve by means of ANOVA (p < 0.05).ResultsAll upper lingual mushroom wires exerted significantly lower forces than the straight wire. Lower mushroom archwires were stiffer than their upper counterparts, which were longer and featured inset bends. In the lower arch, similar levels of forces were recorded for the two types of wire. Load-deflection curves were higher for the straight wires, and stiffness increased proportionally with their diameter.ConclusionsThe stiffness of an archwire is a function of its diameter, length and the alloy it is made from. In lower lingual wires, there is little difference in stiffness between mushroom and straight wires, but in upper wires, the straight version is considerably stiffer. The greater bearing effect exhibited by the straight wire in the working and finishing phases makes it less susceptible to bowing effect and therefore preferable for sliding mechanics during en masse retraction, particularly in the upper arch.

3D technology to measure dental arches and create a template for lingual brackets technique

“…Therefore, authors who compared in vitro the two types of mushroom and straight archwire observed that the advantages and disadvantages of some orthodontic movements varied for each archwire according to the treatment phase. 19,20 We believe that more studies on archwire shape should be performed (in vitro and in vivo) because it is still not possible to state which archwire shapes -mushroom, straight wire, Christmas tree or anatomical (the forms found in this study)-will be more suitable for treatment with the lingual technique. Therefore, the professional will have the opportunity to choose the shape of the archwire that better suits according to the clinical case being treated and, if possible, a template to assist in the orthodontic treatment.…”

“…Therefore, authors who compared in vitro the two types of mushroom and straight archwire observed that the advantages and disadvantages of some orthodontic movements varied for each archwire according to the treatment phase. 19 , 20 …”

“…A previous study analyzing the shapes and dimensions of dental arches in digital 3D models for the use in lingual straightwire technique showed that more cervical archwire setting promotes smaller inter-bracket distance. 15 Although this strategy allowed reduction of the typical insets and offsets of the dental arch lingual surfaces, it hampers orthodontic mechanics in certain movements 19,20 and may cause gingival inflammation. 21 Furthermore, a specific assembly with resin pads is required to compensate the distance between the lingual surface and the base of the bracket.…”

“…Although this strategy allowed reduction of the typical insets and offsets of the dental arch lingual surfaces, it hampers orthodontic mechanics in certain movements 19 , 20 and may cause gingival inflammation. 21 Furthermore, a specific assembly with resin pads is required to compensate the distance between the lingual surface and the base of the bracket.…”

The biomechanics of posterior maxillary arch expansion using fixed labial and lingual appliances

“…7 Prior research has also demonstrated significant differences in the biomechanical systems of straight and mushroom lingual archwires. 7,8 Dental arch expansion through an engaged archwire is one of the strategies used in orthodontics to resolve dental crowding. Grauer and Proffit 9 demonstrated that fully customized lingual orthodontic appliances were accurate in achieving the goals planned in the initial set-up with the exception of the full amount of planned expansion.…”