The effect of electric spot-welding on the mechanical properties of different orthodontic wire alloys

Abstract

The aim of this study was to test the hypothesis that there is a direct relationship between surface structure and tensile strength of orthodontic alloys submitted to different levels of welding current. Three types of alloys were assessed. One hundred and eight cross-sectional test specimens ("X") were made, 18 for each wire combination, and divided into 6 groups: SS (steel-steel); SN (steel-NiTi); SB (steel-Beta-Ti); NN (NiTi-NiTi); NB (NiTi-Beta-Ti) and BB (Beta-Ti-Beta-Ti), submitted to 6 spot-welding procedures at different levels of current (Super Micro Ponto 3000). Student-Newman-Keuls, Wilcoxon signed-rank, and Kruskal-Wallis tests were used (p < .05). Statistical difference was found between SN group and all the other alloy combinations (p < .05). Initial roughness of alloys ranged from .04 to .55 Ra, with statistical difference between groups (p < .001). The hypothesis was rejected and the tensile strength of Ti-alloys combinations Steel × Beta-Ti was significantly affected by the current level at P50, which changed the properties and structure of the wires.

Are Metal Ions That Make up Orthodontic Alloys Cytotoxic, and Do They Induce Oxidative Stress in a Yeast Cell Model?

“…Each part of an orthodontic appliance, whether an archwire, bracket or band, may differ from other parts by their composition and characteristics [1]. To make a fixed orthodontic appliance, some parts have to be joined together, whether that be by brazing, soldering or welding [2]. Many metallic alloys, ranging from different series of stainless steel, to nickel-titanium, pure titanium, and cobalt-chromium, are being used for manufacturing orthodontic devices, and all of them possess unique physical and mechanical properties [3].…”

Comparison of Tensile Strengths of Welded Orthodontic Tubes Using Electrical Resistance and Argon Laser Welding

“…Previous studies have been conducted on attachment to orthodontic wires using different methods of welding , testing their tensile bond strength and other characteristics of attachment. (Nascimento et al, 2012) (Iijima, brantley, Yuasa, Muguruma, et al, 2008) (Iijima, brantley, Yuasa, Kawashima, et al, 2008). conclusions from these studies have shown that both these types of welding show desirable characteristics with lasers being more clinically efficient due to concentrated areas of heating but have been used less due to factors considering affordability.…”

Comparison between traditional and alternative biocompatible welding techniques used in orthodontic devices

“…The possibility of using different welding methods to overcome this lack of biocompatibility is of great interest to orthodontists. Alloy-free methods such as spot, tungsten inert gas (TIG) (Bock et al, 2009;Fornaini et al, 2009;Rocha et al, 2006;Wang and Welsch, 1995), a well-known gas tungsten arc welding and laser welding are alternatives (Bock et al, 2008b;Nascimento et al, 2012;Muguruma et al, 2018). Laser increased its application in the orthodontic field (Nalcaci and Gokakoglu, 2013) and may also be used for welding.…”

“…Spot welding presents higher biocompatibility (Nascimento et al, 2012;Sestini et al, 2006) but the mechanical strength may vary according to wire and joint configuration (Nascimento et al, 2012). TIG welding and laser welding present no galvanic corrosion, small focus and argon coating that prevents oxidation around the joint (Heidemann et al, 2002;Sestini et al, 2006;Solmi et al, 2004;Perveen et al, 2018;Muguruma et al, 2018).…”