an impression 140 at its distal end 116 possibly a hex shaped socket 142 additionally the anchor body may be formed with a threaded receptacle to 144 to receive a threaded screw or bolt 112 when the anchor body 111 goes through osseointegration see http en wikipedia org wiki osseointegration incorporated herein by reference in its entirety the reverse thread wraps 138 may be immersed in healed and or healing osseous tissue with the reverse tooth face or faces 134 bearing against the tissue thus when for example a mechanical unscrewing torque tu and or pulling or extraction force fu may be applied to the anchor 110 particularly to the screw or bolt 112 which may tend to rotate the anchor 110 in a direction opposite to the turning in direction i the reverse tooth face or faces 134 may bear a reaction fr by compression of the osseous tissue since the reverse tooth face or faces 134 which may be tilted in relation to the longitudinal axis l at the reverse angle u03b2 the reaction fr which may operate in an inward direction may effect an equivalent reaction force feq which may act to resist an outwards movement of the anchor 110 this may have the effect of relying on compression strength of the healing and or healed tissue to negate the unscrewing torque tu and or extraction force fu instead of relying on shear forces between the anchor body 111 and the substrate 113 as is well known in the art compression strength of healed and particularly of healing tissues may be considerably greater than those developed by shear between the anchor body 111 and the substrate 113 thus.