Roentgenological detection of casting defects in cobalt-chromium alloy frameworks

A method for non-destructive X-ray investigation of casting defects in cobalt-chromium prosthetic frameworks has been developed and tested. The attenuation properties of a cobalt-chromium alloy were studied. A dental X-ray machine with a tube voltage working at 70 kVp and a focus-film distance of 45-50 cm on dental ultraspeed film made it possible to detect defects representing 10% or less of the thickness of cobalt-chromium details with dimensions between 0.6 and 3.0 mm. The frequency and site of internal defects in sixty-six frameworks were investigated. Of the sixty-six frameworks only two were without roentgenologically visible defects. In the other sixty-four frameworks 294 pores or cracks were recorded. The defects were mostly situated in the saddles. Porosities occurred in 53% of the saddlebar regions. The results confirmed the need for a non-destructive routine test of prosthetic frameworks.