[Materials science studies on the soldering of different orthodontic wires]

In orthodontic technique both soldering and welding are standard methods for the application of auxiliaries and for the modification of force systems by joining wires of different cross-sections. Two cobalt-chromium alloys (Blue Elgiloy, Crozat) and an austenitic stainless steel alloy (Remanium) were soldered by an electrochemically generated hydrogen-oxygen flame forming an overlapped joint design. For characterization of the soldered joint testing procedures included microhardness tests, metallographic examination, tension-shear tests and surface analysis of the fractured joints by scanning electron microscopy. For any given soldering technique with an overlapped joint design the correct joint length is determined by the ratio t/s = 3 (t = overlapped length; s = diameter of the smaller wire).