Abstract
Welding of metals and alloys is important to Dentistry for fabrication of dental prostheses. Several methods of soldering metals and alloys are currently used. The purpose of this study was to assess, using the flexural strength testing, the efficacy of two processes Nd:YAG laser and TIG (tungsten inert gas) for welding of pure Ti, Co-Cr and Ni-Cr alloys. Sixty cylindrical specimens were prepared (20 of each material), bisected and welded using different techniques. Four groups were formed (n=15). I: Nd:YAG laser welding; II- Nd:YAG laser welding using a filling material; III- TIG welding and IV (control): no welding (intact specimens). The specimens were tested in flexural strength and the results were analyzed statistically by one-way ANOVA. There was significant differences (p<0.001) among the non-welded materials, the Co-Cr alloy being the most resistant to deflection. Comparing the welding processes, significant differences (p<0.001) where found between TIG and laser welding and also between laser alone and laser plus filling material. In conclusion, TIG welding yielded higher flexural strength means than Nd:YAG laser welding for the tested Ti, Co-Cr and Ni-Cr alloys.
Highlights
Welding is a widely used process during fabrication of dental prostheses
TIG welding increased the flexural strength of Ti, Co-Cr, Ni-Cr as the welded cylinders presented higher flexural strength than non-weld cylinders
Laser welding of Co-Cr and Ni-Cr alloys resulted in low flexural strength (464 ± 70 MPa; 460 ± 276 MPa)
Summary
Welding is a widely used process during fabrication of dental prostheses. Several techniques are currently in use and each of them has benefits and disadvantages. The choice for a welding method will depend on whether the technique produces enough heat to join the materials without distortion and preserves their properties, whether the materials to be welded are similar or different metals/alloys, and which would be the procedural costs [1]. Laser welding is a low-cost and safe process and may be performed close to plastics, resins or ceramics parts of a dental prosthesis without risks of damage because heating does not spread too far away from the welded site. This technique requires a small gas protected zone to reduce irregularities and internal defects within the welding site that could result in poor weld resistance
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