Abstract: An elongate cylindrical body member is adapted for permanent anchoring of its lower end into bone tissue and constructed to support an attached device such as a tooth at its upper end. The body member has an external screw thread formed in its outer surface, and at least one cavity defined therein adjacent its bottom end. Each cavity forms at its intersection with the screw thread at least one cutting edge for self-tapping as the body member is screwed into the bone tissue. Such cavity defines a total volume within the outer surface of said body member sufficient to retain all the bone tissue material which is removed as a result of the self-tapping operation.