Self-ligating orthodontic brackets

Abstract

An orthodontic bracket comprises a bracket body with a mesial distal extending arch wire slot and a ligating latch spring member having the form of a thin flat metal strip. The spring member comprises along its length, in the order stated, an anchor portion anchored in the bracket body, a flexing portion in which the majority of the flexing takes place, a ligating portion that closes the slot mouth and engages any arch wire therein, and a latching portion by which the spring member is latched to the bracket body. The spring member may comprise a biasing portion between the flexing and ligating portions at the slot occlusal surface, or between the ligating and latching portions at the slot gingival surface, this biasing portion being convex toward the slot lingual wall and protruding into the slot to press the arch wire into the respective slot wall junction for more precise control. The bracket body may be made as two mirror image parts which are laser welded together and between which the spring member is mounted. The latches between the spring member and the bracket body may comprise notches in the spring edges that are engaged by latch sears on the body, and two labially lingually spaced sears may be provided. Preferably the spring member is made of a nickel titanium shape memory alloy. The bracket body may have two pairs of tie wings for reception of an external ligature between which the spring member is disposed.