EFFECTS OF 3 SOLDERING TECHNIQUES ON THE STRENGTH OF HIGH-PALLADIUM ALLOY SOLDER JOINTS

Statement of problem. Little information is available on the optimum t echnique for soldering high-palladium alloys, which have gained consid erable popularity for prosthodontic applications. Purpose. The objecti ve of this study was to compare the flexural stress at the proportiona l limit of four noble dental alloy specimens soldered with torch, oven , and infrared techniques. Materials and methods. The high-palladium a lloys studied were Legacy XT (Jelenko), Freedom Plus (Jelenko), and IS 85 (Williams/Ivoclar). A gold-palladium alloy, Olympia (Jelenko), ser ved as the control. Thirty round bars, 18 x 3 mm, were cast from each alloy, cut in half, aligned, and joined using Olympia Pre solder (Jele nko) for the gas-oxygen torch and the infrared technique and Alboro LF solder (Jelenko) for the oven technique. Each soldered bar was subjec ted to three-point bending, and the maximum elastic stress or strength of the solder joint was calculated at the proportional limit. Data we re analyzed by two-way ANOVA and the Ryan-Einot-Gabriel-Welsch (REGW) multiple range test at the 0.05 level of significance. Results. There was no significant difference between torch and oven-soldering, but bo th were significantly different from the infrared technique. ANOVA sho wed a significant difference between alloys, but this difference could not be detected with the REGW test. SEM examination of the fracture s urfaces revealed grooves associated with the path of crack propagation . X-ray energy-dispersive spectroscopic analysis failed to detect copp er in the solders, and there were no significant changes in the solder compositions after the melting procedures. Conclusions. All three tec hniques can yield satisfactory solder joints in high-palladium alloys. These joints should be well-polished to achieve optimal strength.