The machining of cobalt-chromium alloy in partial denture construction

Purpose: To investigate the performance of different rotary instruments whe n machining cobalt-chromium alloy. Materials and Methods: One tungsten carb ide bur, 1 diamond bur, and 2 aluminum oxide abrasive points (pink stones) of different diameter were used to machine cobalt-chromium alloy under stan dardized conditions. The rate of metal removal was determined and the resul ting surfaces and bur wear were investigated using scanning electron micros copy and energy dispersive analysis. Results: Although the larger diameter pink stone was shown to be the most efficient instrument, the tungsten carb ide bur produced the smoothest surface. Conclusion: Because of its low cost and high cutting efficiency, the pink stone is well suited for laboratory use. The tungsten carbide bur is the preferred instrument for clinical use.