title: Deflection load characteristics of laser-welded orthodontic wires.
abstract: OBJECTIVE
  To compare the deflection load characteristics of homogeneous and heterogeneous joints made by laser welding using various types of orthodontic wires.
  
  
  METHODS
  Four kinds of straight orthodontic rectangular wires (0.017 inch × 0.025 inch) were used: stainless-steel (SS), cobalt-chromium-nickel (Co-Cr-Ni), beta-titanium alloy (β-Ti), and nickel-titanium (Ni-Ti). Homogeneous and heterogeneous end-to-end joints (12 mm long each) were made by Nd:YAG laser welding. Two types of welding methods were used: two-point welding and four-point welding. Nonwelded wires were also used as a control. Deflection load (N) was measured by conducting the three-point bending test. The data (n  =  5) were statistically analyzed using analysis of variance/Tukey test (P < .05).
  
  
  RESULTS
  The deflection loads for control wires measured were as follows: SS: 21.7 ± 0.8 N; Co-Cr-Ni: 20.0 ± 0.3 N; β-Ti: 13.9 ± 1.3 N; and Ni-Ti: 6.6 ± 0.4 N. All of the homogeneously welded specimens showed lower deflection loads compared to corresponding control wires and exhibited higher deflection loads compared to heterogeneously welded combinations. For homogeneous combinations, Co-Cr-Ni/Co-Cr-Ni showed a significantly (P < .05) higher deflection load than those of the remaining homogeneously welded groups. In heterogeneous combinations, SS/Co-Cr-Ni and β-Ti/Ni-Ti showed higher deflection loads than those of the remaining heterogeneously welded combinations (significantly higher for SS/Co-Cr-Ni). Significance (P < .01) was shown for the interaction between the two factors (materials combination and welding method). However, no significant difference in deflection load was found between four-point and two-point welding in each homogeneous or heterogeneous combination.
  
  
  CONCLUSIONS
  Heterogeneously laser-welded SS/Co-Cr-Ni and β-Ti/Ni-Ti wires provide a deflection load that is comparable to that of homogeneously welded orthodontic wires.
authors: Department of Dental and Biomedical Materials Science, Nagasaki University Graduate School of Biomedical Science, Nagasaki, Japan. ewatana@nagasaki-u.ac.jp
authors: Etsuko
authors: E
authors: Watanabe
authors: Garrett
authors: G
authors: Stigall
authors: Waleed
authors: W
authors: Elshahawy
authors: Ikuya
authors: I
authors: Watanabe
mesh_terms: D000704:Analysis of Variance; D003722:Dental Alloys / Q000737:chemistry*; D012994:Dental Soldering / Q000379:methods*; D003799:Dental Stress Analysis / Q000379:methods; D007834:Lasers; D008422:Materials Testing / Q000379:methods; D008855:Microscopy, Electron, Scanning; D009969:Orthodontic Wires; D014896:Welding / Q000379:methods*
chemical_list: D003722:Dental Alloys