Laser-welded vs soldered nonprecious alloy dental bridges: a comparative study.

The high cost of gold alloy has caused the dental profession to begin substituting nonprecious alloy for the framework in porcelain fused to metal bridges. Especially in long-span bridges it may be advantageous to make multiple castings and then join them for a better fit. As opposed to the highly successful soldering of gold, soldered nonprecious alloy bridges have a great failure rate in the mouth. Removal of and remaking of the bridges is thus the result. This study compares nonprecious units that have been laser-welded with those conventionally soldered. Seven identical bridges of three units were cast in a popular alloy composed of 74-78% nickel, 12-15% chromium, 4-6% molybdenum, and 1.8% maximum beryllium. One served as a control, while the remaining six were all cut in the same place. Of these, three were soldered with a gas oxygen torch. The other three were welded with a Nd-YAG laser. Better and stronger joints unlikely to fracture in the mouth were found with the laser-welded specimen.