Abstract: The invention concerns a drill head for the attachment of bone drills or bone milling cutters, as well as the bone drills or milling cutters themselves, especially for preparing bone cavities into which enossal prosthetic elements can be inserted. The designation "bone drill" or "bone milling cutter" is meant to include all drills or cutters with which, in the field of human or veterinary medicine, including the dental field, material can be removed from teeth, bones and bone-like tissue, as well as from corresponding substitute materials. Finally the invention concerns also dental and half-implants, being particularly simply inserted with these instruments.

Abstract: A drilling apparatus for the preparation of bone cavities includes a plurality of drills which are simultaneously driven in opposite direction with the cutting surfaces of each drill overlapping the cutting surfaces of at least one other drill to provide intersecting bone cavities. The drills may be driven by gearing located within the drill head or by gearing located in an attachment suitable for connection to a conventional drill head having a single output drive. The drills may be disposed along a straight or curved line or may be disposed in a triangular relationship with the axis of rotation of one of the drills being transversely movable relative to the axis of rotation of another drill.