A novel post and core assembly for the implantation of a dental prosthesis is set forth in the present invention. Comprised of separate post and core elements of a laser weldable material, the assembly allows for an infinite number of precise lengths and angular deviation between the post and core to precisely align a prosthesis with existing teeth/prostheses without delays in fabrication outside of the dentist's office, as is typically required in prior art assemblies. The post and/or core may be cut to the desired length and angle and welded, on site, with a minimal requirement for fabrication equipment.