An orthodontic bracket for attaching an archwire to a tooth comprising: a body including a base for attachment to the tooth, the body having an occlusal-gingivally extending opening , a mesial gingival tie wing , a distal gingival tie wing, and at least one occlusal tie wing , said gingival and occlusal tie wings projecting from a labial surface of said body, said mesial gingival tie wing and said distal gingival tie wing having a thread; an archwire slot extending mesiodistally across said body and between the gingival and occlusal tie wings at opposed mesial and distal sides of said body to accommodate the archwire ; a locking shutter including at least one resilient arm member at one end and a retaining portion at another end, said locking shutter moveable between an open position in which placement and removal of said archwire is facilitated and a closed position in which placement and removal of said archwire is inhibited; a retaining groove : formed in an occlusal wall of said gingival tie wings; and extending mesiodistally through the body , for releasably retaining said retaining portion of said locking shutter in said closed position; and a mesial blocking member projecting mesially from a mesial face of said mesial gingival tie wing , and a distal blocking member projecting distally from a distal face of said distal gingival tie wing, the mesial and distal blocking members extending labial-lingually across respective mesial and distal ends of said retaining groove, said mesial blocking member having a threaded fastener that engages said thread of said mesial gingival tie wing and said distal blocking member having a threaded fastener that engages said thread of said distal gingival tie wing . a body including a base for attachment to the tooth, the body having an occlusal-gingivally extending opening , a mesial gingival tie wing , a distal gingival tie wing, and at least one occlusal tie wing , said gingival and occlusal tie wings projecting from a labial surface of said body, said mesial gingival tie wing and said distal gingival tie wing having a thread; an archwire slot extending mesiodistally across said body and between the gingival and occlusal tie wings at opposed mesial and distal sides of said body to accommodate the archwire ; a locking shutter including at least one resilient arm member at one end and a retaining portion at another end, said locking shutter moveable between an open position in which placement and removal of said archwire is facilitated and a closed position in which placement and removal of said archwire is inhibited; a retaining groove : formed in an occlusal wall of said gingival tie wings; and extending mesiodistally through the body , for releasably retaining said retaining portion of said locking shutter in said closed position; and formed in an occlusal wall of said gingival tie wings; and extending mesiodistally through the body , for releasably retaining said retaining portion of said locking shutter in said closed position; and a mesial blocking member projecting mesially from a mesial face of said mesial gingival tie wing , and a distal blocking member projecting distally from a distal face of said distal gingival tie wing, the mesial and distal blocking members extending labial-lingually across respective mesial and distal ends of said retaining groove, said mesial blocking member having a threaded fastener that engages said thread of said mesial gingival tie wing and said distal blocking member having a threaded fastener that engages said thread of said distal gingival tie wing . <EOS>