A semi-worked piece of composite material for producing artefacts/devices for dental and/or odontoiatric use such as posts and/or stumps and/or dental crowns for example, comprises a polymeric matrix and a multiplicity of mechanically resistant fibres nested in the polymeric matrix; in this semi-worked piece the resistant fibres are arranged in a predetermined number of reinforcing layers that are substantially planar and are disposed in mutually overlapped relationship.