The post (50) has an insertion piece (80) designed with an outer contour (96) and inserted into an implant (2), where the insertion piece forms a rotation-secured connection with an interface (22) of an opening area (20). An end piece is connected to an insertion piece, and prismatically tapers with prism surfaces (98) while retaining the outer contour at an apical end of the implant, where angle between a longitudinal direction (32) of the implant and the prism surfaces amounts to 15 degrees. Expansion (a) of the insertion piece in the longitudinal direction ranges between 0.2 and 0.4 mm. An independent claim is also included for a casting post.