The subject of the invention is automation of process and apparatus for computer-controlled preparation of teeth, during said process preparing the tooth-stump(s) holding the prosthetic piece as pillar(s), takes place on basis of a digital plan of three dimensions, with a combined laser head of small size, matching the size of the oral cavity, moving along a trajectory fixed to a frame of face-bow controlled by a computer, preparing teeth-stump(s) before placing into the mouth the prosthetic piece produced by CAD/CAM technique.