The present document describes a drill-bit which achieves both the rigidity and a fast rate of penetration. The drill-bit comprises a cone shaped central portion comprising a plurality of ribs protruding from the central portion and defining a plurality of blades. The blades are curved along a direction of a longitudinal axis of the cone to facilitate insertion into a hole when rotating in a first direction, and exit from the hole when rotating in a second direction opposite the first direction. The drill-bit comprises a plurality of polycrystalline diamond cutters (PDC) on the blades provided in a first position for cutting the hard structure as the drilling-bit rotates in the first direction, and a plurality of up-drill PDC cutters provided in a second position for cleaning the hole as the drill-bit rotate in the second direction to exit the hole.