Patent Description:
This application generally relates to self-ligating orthodontic brackets, and more specifically, to such brackets having a biased ligating member designed for improved overall performance.

Orthodontic treatment typically involves orthodontic devices designed to apply mechanical forces to a patient's teeth to urge improperly positioned teeth into a correct alignment. One form of orthodontic treatment includes the use of self-ligating orthodontic brackets, where a single bracket is adhered to each individual tooth in a subset of teeth with a bonding material or other adhesive. Once the brackets are in position on the teeth, an archwire is inserted through a slot formed on each of the brackets. In this configuration, tightening of the archwire applies pressure on the brackets, which in turn, urge movement of the teeth into a desired position and orientation.

In some designs, self-ligating brackets may include a ligating door or slide with a spring or other biasing element to help retain the archwire in position within the slot. The ligating slide is movable between closed and open positions to allow insertion and retention of the archwire within an archwire slot of the bracket. <CIT>, <CIT>, and <CIT> all disclose examples of orthodontic brackets comprising a ligating slide that is moveable between closed and open positions and a biasing element such as a spring or pin. In such designs, the biasing element provides a retention force that holds the ligating slide in either the open or closed position for improved use. In many instances, the ligating slide is typically cycled (e.g., opened and closed) approximately <NUM> to <NUM> times during the course of orthodontic treatment. Accordingly, conventional self-ligating brackets are designed to optimize the retention force of the spring for short life-cycles. On occasion, however, the number of cycles for specific treatments may increase due to additional archwire adjustments, additional archwire changes, or auxiliary treatment mechanics. Further, some patients learn how to operate the ligating slide and may "play" with their brackets by opening and closing the ligating slide, which results in additional open and close cycles, thereby degrading the spring retention force over time. Excessive reduction of the spring retention force may result in inadvertent opening of the ligating slide during the treatment phase, which may increase the likelihood of disengagement of the archwire from the bracket and result in treatment inefficiency due to a lack of proper mechanical force being applied to the tooth. Moreover, when the archwire disengages from the slot, a practitioner may need to address any issues and/or replace the bracket/archwire as needed, which may extend overall treatment time for the patient. In other instances, reduction of the spring retention force may result in a complete disengagement of the ligating slide from the bracket.

Accordingly, the present inventors have identified a need for an improved design of an orthodontic bracket for providing an effective and consistent retention force for a significant number of opening/closing cycles to ensure optimum performance for a variety of uses and circumstances. Such a design maximizes the number of open and close cycles the ligating slide and biasing element can tolerate without experiencing a dramatic reduction in the retention force that holds the ligating slide in either the open or closed position, thereby minimizing long-term performance issues of the orthodontic bracket. In addition, the improved design secures the ligating slide against the orthodontic bracket to prevent complete disengagement from the bracket. Additional aspects and advantages will be apparent from the following detailed description of example embodiments, which proceeds with reference to the accompanying drawings.

The invention is defined by an orthodontic bracket with the features of claim <NUM>.

With reference to the drawings, this section describes various embodiments of an orthodontic bracket system and its detailed construction and operation. Throughout the specification, reference to "one embodiment," "an embodiment," or "some embodiments" means that a described feature, structure, or characteristic may be included in at least one embodiment of an orthodontic bracket. Thus, appearances of the phrases "in one embodiment," "in an embodiment," or "in some embodiments" in various places throughout this specification are not necessarily all referring to the same embodiment. Further, the described features, structures, and characteristics may be combined in any suitable manner in one or more embodiments. In view of the disclosure herein, those skilled in the art will recognize that the various embodiments can be practiced without one or more of the specific details or with other methods, components, materials, or the like.

In the following description, certain components of the orthodontic brackets are described in detail. It should be understood that in some instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring more pertinent aspects of the embodiments.

<FIG> illustrates an example embodiment of an orthodontic self-ligating bracket <NUM> including a bracket body <NUM> with a sliding door <NUM> designed to move relative to the bracket body <NUM> between a closed position and an open position. To establish a frame of reference, the following description (unless otherwise indicated) refers to the bracket <NUM> as being attached to a labial surface of a tooth on an upper jaw of the patient. For example, with reference to the bracket body <NUM> illustrated in <FIG>, when the bracket body <NUM> is mounted to the tooth in the patient's upper jaw, the bracket body <NUM> has a lingual side <NUM> (see also <FIG>), a labial side <NUM>, an occlusal side <NUM>, a gingival side <NUM>, a mesial side <NUM>, and a distal side <NUM>. Terms such as labial, lingual, mesial, distal, occlusal, and gingival used to describe the bracket <NUM> in this specification are relative to this frame of reference. It should be understood, however, that the embodiments of the disclosed subject matter are not limited to the chosen reference frame and descriptive terms, as the orthodontic bracket <NUM> may be used on other teeth and in other orientations within the oral cavity. For example, the bracket <NUM> may also be located on an anterior tooth in the lower jaw or maxilla and be within the scope of the disclosed subject matter. Those having ordinary skill in the art will recognize that the descriptive terms used herein may not directly apply when there is a change in the frame of reference. The disclosed subject matter is intended to be independent of location and orientation within the oral cavity and the relative terms used to describe the illustrated embodiments are to provide a clear description in conjunction with the drawings. As such, the relative terms labial, lingual, mesial, distal, occlusal, and gingival in no way limit the disclosed subject matter to a particular location or orientation but are instead offered to aid in understanding the disclosed subject matter.

With general reference to <FIG>, the bracket <NUM> includes a bracket body <NUM> mountable to a tooth via a base structure <NUM> (see <FIG>) on the lingual side <NUM> of the bracket body <NUM>. The base structure <NUM> may include a series of grooves or ridges for receiving an adhesive or other bonding material to provide a solid connection with the tooth and prevent dislodging. The bracket body <NUM> further includes an archwire slot <NUM> extending across the bracket body <NUM> from a first side to a second side generally in a mesial-distal direction, such as from the mesial side <NUM> to the distal side <NUM>. The archwire slot <NUM> includes a generally planar base surface <NUM> extending across the length of the slot <NUM> and opposing side walls <NUM>, <NUM> extending upwardly from the base surface <NUM> in the labial direction. In some embodiments, the side walls <NUM>, <NUM> are perpendicular to the base surface <NUM> to form a generally rectilinear archwire slot <NUM> (e.g., a slot having a generally rectangular or square shape), the archwire slot <NUM> having open ends formed along the labial side <NUM>, and along the mesial and distal sides <NUM>, <NUM>, respectively, of the bracket body <NUM>.

With reference to <FIG>, the bracket body <NUM> further includes a sliding ligating member or door <NUM> arranged on the labial side <NUM> of the bracket body <NUM> for retaining an archwire (not shown) within the archwire slot <NUM>. The sliding door <NUM> includes a base <NUM> and a pair of side rails <NUM>, <NUM> designed to be slidably received within a corresponding pair of guides <NUM>, <NUM> formed on the bracket body <NUM>. Once the sliding door <NUM> is inserted into position within the bracket body <NUM>, the side rails <NUM>, <NUM> and guides <NUM>, <NUM> work together to restrict movement of the sliding door <NUM> to the gingival-occlusal direction when the sliding door <NUM> is opened or closed. When the sliding door <NUM> is in the closed position, the archwire is urged downwardly into the archwire slot <NUM> to apply pressure to the bracket body <NUM> and the patient's teeth to produce the desired tooth movement.

With collective reference to <FIG>, the bracket body <NUM> further houses a resilient biasing member <NUM> designed to impart force upon the sliding door <NUM> to help maintain the sliding door <NUM> either in a closed position or an open position as further described below with particular reference to <FIG>. With particular reference to <FIG>, the biasing member <NUM> extends generally upright along the lingual-labial direction, with a lower portion of the biasing member <NUM> inserted into and retained within a seat <NUM> formed along a labial surface <NUM> of the bracket body <NUM>, the seat <NUM> opening along the labial surface <NUM> and extending downwardly through the bracket body <NUM> from the labial surface <NUM> to the base surface <NUM> on the lingual side <NUM> of the bracket body <NUM> (see <FIG>). In one preferred configuration, the seat <NUM> opens onto the base surface <NUM> as illustrated in <FIG>, but in other embodiments, the seat <NUM> may be closed off along the base surface <NUM>. In configuration where the seat <NUM> opens onto the base surface <NUM>, an adhesive may be applied from the lingual side <NUM> or from the labial surface <NUM> to adhesively attach the lower portion of the biasing member <NUM> to the bracket body <NUM>. In other embodiments, the seat <NUM> may include one or more side walls <NUM> each having a ridged profile that extends toward a central portion of the seat <NUM>, the side walls <NUM> designed to interfere with and firmly grip the biasing member <NUM> within the seat <NUM> to further secure the biasing member <NUM> in position. Further details of the biasing member <NUM> are provided below.

<FIG> collectively illustrate features of the biasing member <NUM> and its interaction with the sliding door <NUM> to retain the sliding door <NUM> in either the open or closed conditions as desired. <FIG> illustrate an example embodiment of the biasing member <NUM> in accordance with one embodiment. With general reference to <FIG>, the biasing member <NUM> is arranged in a generally T-shaped configuration with a generally upright stem <NUM> and a cross member <NUM> supported by and disposed generally orthogonal to the stem <NUM>. In some embodiments, the cross member <NUM> may instead be skewed or angled relative to the upright stem <NUM> to vary the retention force as needed. The cross member <NUM> includes a first projection <NUM> extending upwardly from the cross member <NUM> at a first end <NUM> thereof, and a second projection <NUM> extending upwardly from the cross member <NUM> along a second end <NUM> thereof. The projections <NUM>, <NUM> are arranged along respective axes that are generally parallel to the axis of the stem <NUM>, and extend along the lingual-labial direction, the projections <NUM>, <NUM> being offset from one another to define a gap or opening <NUM> therebetween. In some embodiments, the stem <NUM> may further include one or more ribs <NUM> formed along a side surface <NUM> extending between a first (front) surface <NUM> and an opposite second (rear) surface <NUM>. As noted previously, the ribs <NUM> may interact with the one or more side walls <NUM> to help secure and retain the biasing member <NUM> in position within the seat <NUM> on the bracket body <NUM> (see <FIG>).

With particular reference to <FIG>, the cross member <NUM> further includes a leading edge surface <NUM> extending between the first and second surfaces <NUM>, <NUM> of the biasing member <NUM>. As further described below with reference to <FIG>, the leading edge surface <NUM> defines the perimeter shape of the biasing member <NUM>, whereby the overall shape of the biasing member <NUM> is contained within the first and second surfaces <NUM>, <NUM> as illustrated in <FIG>.

Preferably, the stem <NUM>, cross member <NUM>, and projections <NUM>, <NUM> are formed as unitary, integral components of the biasing member <NUM>. In some embodiments, the biasing member <NUM> may be made of nickel titanium and etched, laser cut, machined (e.g., electrical discharge machining) or otherwise manufactured from a substantially planar stock or sheet to create a biasing member <NUM> with the first surface <NUM> and the opposite second surface <NUM> being substantially planar and the leading edge surface <NUM> extending therebetween. In other embodiments, the biasing member <NUM> may be made of any other suitable material.

<FIG> are each cross-section views of the assembled bracket <NUM> illustrated in the closed and open condition, respectively. With reference to <FIG> (see also <FIG>), the sliding door <NUM> includes a slot <NUM> formed on an underside thereof, the slot <NUM> extending from a front end of the sliding door <NUM> and opening onto a back end thereof. The sliding door <NUM> further includes a ridge <NUM> formed within the slot <NUM> (see <FIG>), where the ridge <NUM> interacts with the resilient member <NUM> as further described in detail below. In some embodiments, the ridge <NUM> may include a ramped guiding surface <NUM> formed along one end, the guiding surface <NUM> leading to a curved tip or end <NUM> formed at an apex of the ridge <NUM>. A stop surface <NUM> extends from the curved end <NUM> toward the underside of the sliding door <NUM>.

With reference to <FIG>, when the sliding door <NUM> is coupled to the bracket body <NUM>, a channel <NUM> is formed therebetween, the channel <NUM> incorporating the slot <NUM> of the sliding door <NUM> and extending from the side wall <NUM> (which forms one wall of the archwire slot <NUM>) and opening along the occlusal side <NUM> of the bracket body <NUM>. While the channel <NUM> and the slot <NUM> are illustrated as being opened along their respective back ends, in other embodiments, one or both of the slot <NUM> and channel <NUM> may instead be closed along the occlusal side <NUM> of the bracket body <NUM> if desired.

With reference to <FIG>, the following discusses positioning of the biasing member <NUM> within the bracket body <NUM>, followed by a discussion of the interaction of the biasing member <NUM> and the ridge <NUM> to facilitate the opening and closing functionality of the sliding door <NUM>. As illustrated in <FIG> and discussed previously with reference to <FIG>, the biasing member <NUM> is positioned within the seat <NUM> formed on the bracket body <NUM>. When the biasing member <NUM> is secured therein, a portion of the stem <NUM> extends from the seat <NUM> and into the channel <NUM>, where the stem <NUM> extends generally upright along the lingual-labial direction. Further, the entirety of the cross member <NUM> is positioned within the channel <NUM> and is arranged generally parallel to the gingival-occlusal sliding direction of the sliding door <NUM>, with the leading edge surface <NUM> (see <FIG>) positioned within the slot <NUM> and generally perpendicular to the topographic surface of the sliding door <NUM>.

With collective reference to <FIG>, when the sliding door <NUM> is in the closed position, the projection <NUM> of the resilient biasing member <NUM> rests against the ridge <NUM> along a beginning portion of the ramped guiding surface <NUM>. In this position, the resilient biasing member <NUM>, via the cross member <NUM> and the projection <NUM>, collectively create a biasing force sufficient to resist unwanted movement of the sliding door <NUM> toward the occlusal side <NUM> of the bracket body <NUM> and thereby maintain the sliding door <NUM> in the closed position.

To open the sliding door <NUM>, a tool (not shown) may be inserted into a recessed region <NUM> formed along the labial surface of the sliding door <NUM>. When the sliding door <NUM> is pulled rearwardly toward the occlusal side <NUM> of the bracket body <NUM>, the ramped surface <NUM> of the ridge <NUM> slides against the projection <NUM> of the resilient biasing member <NUM>. As the sliding door <NUM> continues being pulled rearwardly, the cross member <NUM> of the resilient biasing member <NUM> deflects forwardly and downwardly toward the gingival side <NUM> in an arcuate path about the stem <NUM>. As the resilient biasing member <NUM> continues its deflection, the curved end <NUM> of the ridge <NUM> passes over and beyond the projection <NUM> of the resilient biasing member <NUM>. Once the ridge <NUM> moves beyond the projection <NUM>, the ridge <NUM> is positioned within the gap or opening <NUM> formed between the first and second projections <NUM>, <NUM> (see <FIG>). When the ridge <NUM> is within the opening <NUM>, the force imparted against resilient biasing member <NUM> is released, thereby urging the resilient biasing member <NUM> to return to its upright and unbiased position, with the projection <NUM> being positioned within a pocket <NUM> formed adjacent a forward end of the sliding door <NUM> between a front wall <NUM> on an underside of the sliding door <NUM> and the ridge <NUM>. In some embodiments, an upper portion of the projection <NUM> abuts the front wall <NUM> and an underside of the sliding door <NUM> to ensure that the door <NUM> is securely retained against the bracket body <NUM> when in the open position. In other embodiments, depending on the width of the pocket <NUM> and the width of the projection <NUM>, the projection <NUM> may abut one or both of the front wall <NUM> and the stop surface <NUM> of the ridge <NUM> when the projection <NUM> is in the pocket <NUM>. In this configuration, the projections <NUM>, <NUM> of the resilient biasing member <NUM> help maintain the sliding door <NUM> in the open position to access the archwire slot <NUM> (e.g., to position an archwire or to adjust an existing archwire), and also to ensure that the sliding door <NUM> is not inadvertently opened too far such that it may be decoupled from the bracket body <NUM>. In some embodiments, the second projection <NUM> of the resilient biasing member <NUM> may be eliminated since the projection <NUM> and pocket <NUM> may cooperate to limit the rearward movement of the sliding door <NUM> (as illustrated in <FIG>).

To close the sliding door <NUM> from the open position, the resistive force created by the projection <NUM> against the ridge <NUM> must be overcome. As the sliding door <NUM> moves from the open position to the closed position, the ridge <NUM> moves within the opening <NUM> toward the projection <NUM>. As the ridge <NUM> rides against the projection <NUM>, the cross member <NUM> is deflected forwardly and downwardly toward the gingival side <NUM> in an arcuate path about the stem <NUM>. The cross member <NUM> continues deflecting until the ridge <NUM> moves beyond the projection <NUM>, at which point, the cross member <NUM> deflects along the arcuate path to its original upright and unbiased position (as shown in <FIG>).

<FIG> illustrate various views of another embodiment for a resilient biasing element <NUM> that may be incorporated into the orthodontic bracket of <FIG> in place of the resilient biasing element <NUM> of <FIG>. With reference to <FIG>, the resilient biasing element <NUM> includes many of the same components as the resilient biasing element <NUM> of <FIG>, but notably eliminates the second (rear) projection <NUM> for a more streamlined design. The following passages provide more information regarding the biasing element <NUM>, but in some instances, may only briefly describe certain features of the resilient biasing element <NUM> with the understanding that like features of the resilient biasing elements <NUM>, <NUM> will operate similarly unless noted otherwise. Discussion of such features is omitted to avoid repetition.

With collective reference to <FIG>, the resilient biasing element <NUM> is arranged in a generally inverted-L shape with a generally upright stem <NUM> and a cross member <NUM> supported by and disposed generally orthogonal to the stem <NUM>. In some embodiments, the cross member <NUM> may instead be skewed or angled relative to the upright stem <NUM> to vary the retention force as needed. The cross member <NUM> includes a first projection <NUM> extending upwardly from the cross member <NUM> at a first end <NUM> thereof. The projection <NUM> is arranged along an axis that is generally parallel to the corresponding axis of the stem <NUM> and extends along the lingual-labial direction. In some embodiments, the stem <NUM> may further include one or more ribs <NUM> for further securing the biasing element <NUM> in position within the bracket body <NUM> (see <FIG>), the ribs <NUM> being formed along a side surface <NUM> extending between a first (front) surface <NUM> and an opposite second (rear) surface <NUM>.

With particular reference to <FIG>, the cross member <NUM> further includes a leading edge surface <NUM> extending between the first and second surfaces <NUM>, <NUM> of the biasing member <NUM>. As further described below with reference to <FIG>, the leading edge surface <NUM> defines the perimeter shape of the biasing member <NUM>, whereby the overall shape of the biasing member <NUM> is contained within the first and second surfaces <NUM>, <NUM> as illustrated in <FIG>. Preferably, the stem <NUM>, cross member <NUM>, and projection <NUM> are formed as unitary, integral components of the biasing member <NUM> in a similar fashion as described previously with reference to biasing member <NUM>.

Turning now to <FIG>, the following section discusses operation of the biasing member <NUM> in accordance with one example embodiment. <FIG> are cross-section views of an assembled bracket <NUM> illustrated in the closed and open condition, respectively. The bracket <NUM> includes many of the same features and characteristics of the bracket <NUM> described with reference to <FIG>. Accordingly, many of the features of the bracket <NUM> and the door <NUM> are not further described herein to avoid repetition, with the understanding that they share the same features as the bracket <NUM> and door <NUM> described previously. Accordingly, the following passages focus primarily on how the resilient biasing member <NUM> interacts with the bracket <NUM> and door <NUM>.

With reference to <FIG>, the resilient biasing member <NUM> is received in a seat <NUM> of the bracket <NUM>, with the ribs <NUM> (and any adhesives that may be used) securing the biasing member <NUM> in position. When the biasing member <NUM> is inserted into the bracket body <NUM>, the stem <NUM> extends generally upright along the lingual-labial direction and the cross member <NUM> is generally parallel to the gingival-occlusal sliding direction of the sliding door <NUM>. In this configuration, a portion of the stem <NUM> extends from the seat <NUM> into the channel <NUM>, and the entirety of the cross member <NUM> is positioned within the channel <NUM>. In this arrangement, the leading edge surface <NUM> (see <FIG>) is positioned generally perpendicular to the topographic surface of the sliding door <NUM> positioned within the channel <NUM>.

With reference to <FIG>, when the sliding door <NUM> is in the closed position, the projection <NUM> of the resilient biasing member <NUM> rests against a portion of the ramped guiding surface <NUM> (see <FIG>) of the ridge <NUM> formed underneath the sliding door <NUM>. In this position, the resilient biasing member <NUM>, via the cross member <NUM> and the projection <NUM>, collectively create a biasing force sufficient to resist backward movement of the sliding door <NUM> toward the occlusal side <NUM> of the bracket body <NUM> and thereby maintain the sliding door <NUM> in the closed position.

Turning now to <FIG>, when the sliding door <NUM> is pulled rearwardly toward the occlusal side <NUM> of the bracket body <NUM>, the ramped surface <NUM> of the ridge <NUM> slides against the projection <NUM> of the resilient biasing member <NUM>. As the sliding door <NUM> continues being pulled rearwardly, the cross member <NUM> of the resilient biasing member <NUM> deflects forwardly and downwardly toward the gingival side <NUM> of the bracket <NUM> in an arcuate path about the stem <NUM>. As the resilient biasing member <NUM> continues its deflection, the curved end <NUM> (see <FIG>) of the ridge <NUM> passes over and beyond the projection <NUM> of the resilient biasing member <NUM>. Once the ridge <NUM> moves beyond the projection <NUM>, the ridge <NUM> is positioned behind the first projection <NUM>, with the projection <NUM> being positioned within a pocket <NUM> (see <FIG>) formed adjacent a forward end of the sliding door <NUM> between a front wall <NUM> on an underside of the sliding door <NUM> and the ridge <NUM>. In some embodiments, an upper portion of the projection <NUM> may abut one or both of the front wall <NUM> and the ridge <NUM> when the projection <NUM> is in the pocket <NUM> in a similar fashion as discussed previously with reference to <FIG>. In this configuration, the single projection <NUM> of the resilient biasing member <NUM> helps maintain the sliding door <NUM> in the open position without requiring other contact points between the resilient biasing member <NUM> and the sliding door <NUM>.

In a similar fashion as described previously, to close the sliding door <NUM> from the open position, the resistive force created by the projection <NUM> against the ridge <NUM> must be overcome. As the sliding door <NUM> moves from the open position to the closed position, the ridge <NUM> moves toward the projection <NUM>. As the ridge <NUM> rides against the projection <NUM>, the cross member <NUM> is deflected forwardly and downwardly toward the gingival side <NUM> in an arcuate path about the stem <NUM>. The cross member <NUM> continues deflecting until the ridge <NUM> moves beyond the projection <NUM>, at which point, the cross member <NUM> deflects along the arcuate path to its original upright and unbiased position (as shown in <FIG>).

<FIG> collectively illustrate features of another embodiment of an orthodontic bracket <NUM> (illustrated with the sliding door removed for convenience). As illustrated in <FIG>, the bracket <NUM> includes many of the same features as the orthodontic bracket <NUM> illustrated in <FIG>, although the bracket <NUM> is illustrated another embodiment without a hook on the gingival side (compare to <FIG>). To avoid repetition, such common features of the orthodontic bracket <NUM> are not further discussed herein, with the understanding that the same or similar features of the orthodontic bracket <NUM> apply equally to the orthodontic bracket <NUM> of <FIG>.

Claim 1:
An orthodontic bracket (<NUM>, <NUM>) comprising:
a bracket body (<NUM>, <NUM>) mountable to a tooth, the bracket body including an archwire slot (<NUM>, <NUM>) extending from a first side of the bracket body to an opposite second side, the archwire slot dimensioned to receive an archwire therein, the bracket body further including a seat (<NUM>, <NUM>) formed along a labial surface (<NUM>) of the bracket body;
a ligating member (<NUM>, <NUM>) mountable to the bracket body and movable between a closed position and an open position, wherein at least a portion of the ligating member extends over the archwire slot to retain the archwire within the archwire slot when the ligating member is in the closed position, and wherein the ligating member is offset from the archwire slot to provide access to the archwire when the ligating member is in the open position, the ligating member including a slot (<NUM>) formed along an underside thereof and a ridge (<NUM>, <NUM>) formed within the slot, the ridge further including a ramped guiding surface (<NUM>, <NUM>), the ligating member further including a pocket (<NUM>, <NUM>) formed on the underside of the ligating member;
a channel (<NUM>, <NUM>) formed between the bracket body and the ligating member; and
a resilient biasing member (<NUM>, <NUM>) comprising a lower portion inserted into and retained within the seat, the resilient biasing member further including a stem (<NUM>, <NUM>) extending from the seat and into the channel, the stem extending generally upright along a lingual-labial direction and supporting a cross member (<NUM>, <NUM>) of the resilient biasing member, wherein the cross member is positioned within the channel, the cross member further including a projection (<NUM>, <NUM>) extending upwardly from the cross member at a first end (<NUM>, <NUM>) thereof, wherein the projection is positioned within the pocket when the ligating member is in the open position, and wherein the projection rests against the ridge along a portion of the ramped guiding surface to retain the ligating member in the closed position.