Microhardness evaluation of a two-piece post and core technique

This study compared the microhardness of one- and two-piece cast post cores. Twenty 0.070 inch Whaledent "burn-out" posts were invested in a phosphate investment, cast, and bench cooled to room temperature. Five samples, were grouped by Sturdicast or Midas metal and by casting technique. The specimens were cast in matched pairs with one of each technique per casting ring. The Vickers hardness number sites were centered on the post diameter with the core-to-post head junction used as a baseline, at the following sites: (1) 1.5 mm into the core to post head assembly; (2) at the junction of the post to the post head and core assembly; (3) 1 mm into the post; (4) 2 mm into the post; and (5) 3 mm into the post. There were no significant differences in microhardness at the sites tested for metal or casting technic (p < 0.05). This indicated that a two-piece post and core has similar hardness values to the one-piece casting.