title: Influence of different brazing and welding methods on tensile strength and microhardness of orthodontic stainless steel wire.
abstract: The aim of this study was to compare the mechanical strength and microhardness of joints made by conventional brazing and tungsten inert gas (TIG) and laser welding. A standardized end-to-end joint configuration of the orthodontic wire material in spring hard quality was used. The joints were made using five different methods: brazing (soldering > 450 degrees C) with universal silver solder, two TIG, and two laser welders. Laser parameters and welding conditions were used according to the manufacturers' guidance. The tensile strengths were measured with a universal testing machine (Zwick 005). The microhardness measurements were carried out with a hardness tester (Zwick 3202). Data were analysed using one-way analysis of variance and Bonferroni's post hoc correction (P < 0.05). In all cases, brazing joints ruptured at low levels of tensile strength (198 +/- 146 MPa). Significant differences (P < 0.001) between brazing and TIG or laser welding were found. The highest means were observed for TIG welding (699-754 MPa). Laser welding showed a significantly lower mean tensile strength (369-520 MPa) compared with TIG welding. Significant differences (P < 0.001) were found between the original orthodontic wire and the mean microhardness at the centre of the welded area. The mean microhardness differed significantly between brazing (1.99 GPa), TIG (2.22-2.39 GPa) and laser welding (2.21-2.68 GPa). For orthodontic purposes, laser and TIG welding are solder-free alternatives to joining metal. TIG welding with a lower investment cost is comparable with laser welding. However, while expensive, the laser technique is a sophisticated and simple method.
authors.affiliation: Department of Orthodontics, University School of Dental Medicine, Martin-Luther-University Halle-Wittenberg, Halle/Saale, Germany. drbock@web.de
authors.forename: Jens Johannes
authors.initials: JJ
authors.lastname: Bock
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Fraenzel
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Bailly
authors.forename: Christian Ralf
authors.initials: CR
authors.lastname: Gernhardt
authors.forename: Robert Andreas Werner
authors.initials: RA
authors.lastname: Fuhrmann
mesh_terms: D003722:Dental Alloys; D012994:Dental Soldering; D003799:Dental Stress Analysis; D006244:Hardness; D008422:Materials Testing; D016382:Orthodontic Appliance Design / Q000379:methods*; D009969:Orthodontic Wires; D013193:Stainless Steel; D013718:Tensile Strength; D014025:Titanium; D014896:Welding
chemical_list: D003722:Dental Alloys; D013193:Stainless Steel; D014025:Titanium