The invention relates to a female part (16) for forming a detachable connection between a
prosthesis (13) and a counter-piece (2) which can be secured in the mouth, the female part (16) having a housing (12) and an insert (11). The housing (12) can be fixed to the
prosthesis (13) and has a closed housing terminating face (21), on the edge of which a housing collar (18) is circumferentially provided, and the interior (17) has an inner thread (22) and, in an outer region facing the opening (55) of the interior (17), a conical contact inner surface (19). The insert (11) has an insert terminating face (42), on the edge of which an insert collar (33) is provided, the insert collar having an at least partly curved contact surface (41), which transitions into a free inner surface (40) via an
undercut (58), and having at least one slot (43) extending in the axial direction, and the insert (11) has an outer thread (36) in the region of the insert terminating face (42), the outer thread being used to screw the insert (11) into the inner thread (22) of the housing (12).