Iijima Masahiro, Brantley William A, Yuasa Toshihiro, Muguruma Takeshi, Kawashima Isao, Mizoguchi Itaru
Department of Orthodontics, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan.
J Biomed Mater Res B Appl Biomater. 2008 Jan;84(1):147-53. doi: 10.1002/jbm.b.30856.
Laser welding 0.016 x 0.022 in. beta-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 beta-Ti and Co-Cr-Ni was significantly lower than for control specimens joined by silver soldering, it was sufficient for clinical use. The beta-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 beta-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 beta-Ti. Laser welding beta-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.
通过测量接头拉伸强度、测量激光穿透深度、使用微X射线衍射（micro-XRD）确定金相相以及用扫描电子显微镜（SEM）检查微观结构，对0.016×0.022英寸的β钛、镍钛和钴铬镍正畸钢丝进行了激光焊接研究。焊接电压为150至230V。镍钛组的平均拉伸强度显著低于（p<0.05）大多数其他激光焊接试样组。虽然β钛和钴铬镍的平均拉伸强度显著低于通过银焊连接的对照试样，但足以满足临床使用。β钛正畸钢丝的激光焊接穿透深度比镍钛和钴铬镍正畸钢丝更深。从边界处2mm处获得的激光焊接β钛和镍钛的微XRD图谱与原始试样相似，表明原始微观结构得以保留。当使用190V及更高的输出电压时，接头区域的大多数峰消失或变得弱得多，这可能是由于定向凝固效应，通过对焊接β钛中的细条纹进行SEM观察得到了证实。激光焊接β钛和钴铬镍钢丝在临床上可能是可以接受的，因为接头具有足够的强度，并且原始钢丝中的金相相没有发生很大变化。
