A drill head for preparing the bone of two opposing vertebral bodies to accept the concaval-convex shape of an endoprosthesis includes a form cutter having at least one predetermined milling surface, drive means, and a housing. The form cutter has a profile allowing the drill head to fit in the narrow space between two opposing vertebral bodies in the cervical spine of a patient. The drill head is used in a method for preparing the disc space between adjacent vertebrae of a human spine to receive an endoprosthesis therebetween, the method being performed by contacting at least one vertebral body with a movable form cutter.