An implant (4) is provided with attachment and hole-insert parts (2, 3) with surfaces which have different degrees of finishing and/or degrees of roughness and/or porosities (2f, 2g). Arranged on the surfaces there is at least one dozen (A-B) in which the degree of finishing and/or the degree of roughness and/or the porosity is continuously changed. The changes in porosity in said zones can mirror continuous or discontinuous changes in the bone in question, for example the jaw bone or tooth bone. The continuously changed zones can be obtained with the aid of electrolyte (15) and, connected to the latter, an anode and cathode arrangement (13, 14). When establishing the porosity, it is possible to mask different portions of the respective implant and to control the temperature of the implant.