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

• Main Authors: Leonard Euler Andrade Gomes Nascimento, Rogério Lacerda dos Santos, Matheus Melo Pithon, Mônica Tirre de Souza Araújo, Matilde Gonçalves Nojima, Lincoln Issamu Nojima
• Format: Article
• Language: English
• Published: Associação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol) 2012-06-01
• Series: Materials Research
• Subjects: orthodontic wire; welding; topography; tensile strength
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392012000300011

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.