An anchor to be screwed into a hole and self-lock therein with high initial stability. The anchor has an aggressively-threaded, self-tapping apical end. A central region of the anchor is formed with a plurality of helical flutes and intervening lands. Each land carries a condensing edge. The condensing edges are configured to apply a circumferentially sweeping compressive strain to the interior surface of the host material while the anchor is being screwed into position. A coronal end of the anchor includes a corking feature to mitigate mushrooming around the perimeter of the hole. A helical groove intersects the condensing edges and flutes. The helical groove has a variable pitch and a decreasing depth which functions to squeeze and displace trapped host material thereby enhancing stability and other benefits. In bone applications, the groove hosts material chips which promote and enhance healing.
