Radiological examination of dental castings -- a review of the method and comparisons of the equipment.

The mechanical stability of crowns or bridges as well as frameworks for removable partial dentures depends on factors like thickness and metal structure. The biological compatibility can be influenced by porosities and soldered joints. Radiological testing is a non-destructive method to check defects in dental castings. As dental precious metal alloys have high X-ray absorption, testing of high gold alloys should be performed with a suitable X-ray machine at a tube voltage of 120 kV since the X-ray penetration of dental X-ray units using a tube voltage of 70 to 80 kV is not high enough for these alloys. As the absorption of Co-Cr alloys and of titanium is much lower, these materials can be tested with a dental X-ray apparatus. The radiographs show location and size of metal defects. They enable an examination of metal thickness and content of porosities. Metal defects reducing the biological compatibility or cast stability can be detected prior to clinical fitting.