Joining characteristics of orthodontic wires with laser welding

✍ Scribed by Masahiro Iijima; William A. Brantley; Toshihiro Yuasa; Takeshi Muguruma; Isao Kawashima; Itaru Mizoguchi

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 468 KB
• Volume: 84B
• Category: Article
• ISSN: 1552-4973
• DOI: 10.1002/jbm.b.30856

✦ Synopsis

Abstract

Laser welding 0.016 × 0.022 in. β‐Ti, Ni–Ti, and Co–Cr–Ni orthodontic wires was investigated by measuring joint tensile strength, measuring laser penetration depth, determining metallurgical phases using micro X‐ray diffraction (micro‐XRD), and examining microstructures with an scanning electron microscope (SEM). Welding was performed from 150 to 230 V. Mean tensile strength for Ni–Ti groups was significantly lower (p < 0.05) than for most other groups of laser‐welded specimens. Although mean tensile strength for β‐Ti and Co–Cr–Ni was significantly lower than for control specimens joined by silver soldering, it was sufficient for clinical use. The β‐Ti orthodontic wire showed deeper penetration depth from laser welding than the Ni–Ti and Co–Cr–Ni orthodontic wires. Micro‐XRD patterns of laser‐welded β‐Ti and Ni–Ti obtained 2 mm from the boundary were similar to as‐received specimens, indicating that original microstructures were maintained. When output voltages of 190 V and higher were used, most peaks from joint areas disappeared or were much weaker, perhaps because of a directional solidification effect, evidenced by SEM observation of fine striations in welded β‐Ti. Laser welding β‐Ti and Co–Cr–Ni wires may be acceptable clinically, since joints had sufficient strength and metallurgical phases in the original wires were not greatly altered. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008