Pore distribution and fracture localization of flame-soldered joints in dental gold. A metallographic and microfractographic study.

The occurrence of pores and fatigue fractures in flame-soldered joints of dental gold was measured using fractograms and metallographic preparations. All soldered joints contained pores localized mainly in the solder material adjacent to casting/solder and solder/solder interfaces. The porosity portion of these regions was 20-40 volume per cent, consisting chiefly of pores smaller than 0.1 mm. The fatigue fractures were nearly always situated in the same regions or along the casting surfaces themselves.