HK1141432B - Self-ligating bracket with rotary cover - Google Patents

Description

Self-ligating bracket with rotating cover

Technical Field

The present disclosure relates to self-locking or ligating orthodontic brackets. More particularly, the present disclosure relates to self-ligating orthodontic brackets each having a rotary ligating cover retaining an archwire therein.

Background

Orthodontic treatment typically involves dental work to correct irregularities in teeth and in the relationship of teeth to surrounding tissue. Irregularities may involve malocclusions of varying degrees of severity. Grade 1 malocclusions may, for example, involve spacing irregularities such as overcrowding or cleft (the gap between two adjacent teeth). Class 2 malocclusions may involve overbite situations where the upper anterior teeth project labially over the lower anterior teeth. Class 3 malocclusions, in contrast, may involve an underbite situation where the upper anterior teeth close within the lingual side of the lower anterior teeth. For these and other observed irregularities, treatment typically involves the installation of braces or mechanical tools for repositioning the teeth into proper orthodontic alignment.

Braces typically include orthodontic brackets configured for attachment to the labial or lingual surfaces of teeth or for attachment to metal bands secured around teeth. The brackets typically include archwire slots into which a still flexible, resilient archwire may be engaged. Each bracket is typically bonded to the tooth surface such that the bracket's archwire slot is oriented for engagement with the archwire. Various techniques are used to orient the brackets. For example, an edgewise appliance includes a mouthpiece such that each bracket is oriented and bonded to the tooth such that the archwire slot is perpendicular to the longitudinal axis of the root of the tooth. Alternatively, a straight wire appliance includes braces such that each bracket is oriented and bonded to the tooth such that the archwire slot is parallel to the plane of occlusion (the plane of the occlusal surface of the tooth).

Archwires are typically bent wires of rectangular and circular cross-section that are bent or twisted prior to engagement with the brackets. The memory or restoring force exerted by the archwire on the brackets is used to move the teeth into the desired alignment. Throughout the duration of orthodontic treatment, the orthodontist periodically adjusts the shape of the archwire (as well as the configuration of other attachments such as elastic bands and the like) to achieve proper orthodontic alignment.

Most brackets in use today incorporate tie wings or extensions that project upwardly and downwardly in a gingival-occlusal orientation and require the use of ligatures or ligating modules to retain the archwire within the archwire slot. The ligatures or ligating modules are typically annular elastic loops or wires that are stretched or twisted around the tie wings.

The use of such tie-bands or tie modules has a number of inherent disadvantages, some of which are mentioned herein. The small size of the ligature or ligating module requires a significant amount of time to install the archwire. Because the orthodontist will typically make numerous adjustments to the archwire throughout the orthodontic treatment, the orthodontist will likely remove and replace the ligatures or ligating modules multiple times. Hygiene is another problem because the use of tie-wraps or tie-modules increases the area that may capture food items. Also, under movement due to chewing or other activity, the ligature or ligating module may become completely loose, allowing the archwire to disengage from the archwire slot.

There are other limitations of ligatures or ligating modules with respect to the forces applied to the brackets. For example, labial or outward forces that may be applied to a tooth with a bracket bonded to its labial surface are limited to the strength of the ligature or ligating module in the labial direction. On the same tooth, the force that can be applied in the lingual direction is not so limited (as the force is applied relative to the bracket structure and not the ligature or ligating module).

Conventional bracket systems typically rely on active ligation using resilient or wire ligatures wrapped around the tie wings of the bracket to retain the archwire in the archwire slot. The two areas that most securely retain the archwire are the middle and distal ends of the brackets where resilient or wire ligatures contact the archwire, tying it. This binding creates friction during orthodontic tooth movement and subsequently increases the force required to straighten and slide tooth movement during treatment.

In contrast, passive self-ligating (or so-called frictionless) bracket systems, or bracket systems that do not require conventional ligatures or ligating modules, have been developed that rely on the principle that the forces used to reposition the teeth should not overwhelm the supporting periodontal and facial musculature. The applied force should instead be minimized to a level such that it is just large enough to stimulate cellular activity and thus tooth activity without unnecessarily interfering with the vascularity of the periodontal tissue.

Several self-ligating or self-ligating (ligature-free) orthodontic brackets have been designed. However, most of these have complex designs incorporating components that require expensive machining operations or include multiple separate parts, which increases the variety of failure modes for such pockets. Other designs are rejected by the market due to poor quality or design, lack of use characteristics, difficulty of use, or other factors.

There is therefore a need for an orthodontic bracket that incorporates self-ligating capability and provides a different type of bracket than is currently available.

The foregoing and other objects, features and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings.

Drawings

For a more complete understanding of the present invention, the drawings herein show examples of the invention. However, the drawings do not limit the scope of the present invention. Like reference symbols in the various drawings indicate like elements.

FIG. 1 is an isometric view of a self-ligating orthodontic bracket according to one embodiment of the invention.

FIG. 2 is an exploded isometric view of a self-ligating orthodontic bracket having a bracket base, a rotary ligating cover, and a retaining pin, according to one embodiment of the invention.

FIG. 3 is an exemplary elevational view of a self-ligating orthodontic bracket engaged with an archwire.

FIG. 4 is a cross-sectional view of a self-ligating orthodontic bracket with a rotary ligating cover in a closed position, according to one embodiment of the invention.

FIGS. 5A-5C are cross-sectional views of a rotary ligating cover according to various embodiments of the invention, with the bracket base in a closed and partially open position.

FIG. 6 is a top view of a self-ligating orthodontic bracket with a rotary ligating cover in a partially open position, according to one embodiment of the invention.

FIG. 7 is a top view of a self-ligating orthodontic bracket with a rotary ligating cover in an open position to expose an archwire slot in the bracket base according to one embodiment of the invention.

FIG. 8 is a top view of a rotary ligating cover according to an alternative embodiment of the invention.

FIG. 9 is a top view of a rotary ligating cover according to another alternative embodiment of the invention.

FIG. 10 is a cross-sectional view of a self-ligating orthodontic bracket with a rotary ligating cover in a closed position, according to an alternative embodiment of the invention.

FIG. 11 is a cross-sectional view of a self-ligating orthodontic bracket according to another alternative embodiment of the invention, with the rotary ligating cover in the closed position.

FIG. 12 is a top view of a self-ligating bracket base with a lead-in chamfer on the archwire slot according to one embodiment of the invention.

FIG. 13 is a top view of a self-ligating bracket with a cut-out on the side of a rotating cover, according to one embodiment of the invention.

Detailed Description

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details, that the present invention is not limited to the illustrated embodiments, and that the present invention may be practiced in a variety of alternative embodiments. In other instances, well-known methods, procedures, components, and systems have not been described in detail.

Various operations will be described as multiple discrete steps performed in turn in a manner that is helpful in understanding the present invention. However, the order of description should not be construed as to imply that these operations are necessarily performed in the order they are presented, nor in an order that is subordinate to them.

Turning now to the several views, FIG. 1 is an isometric view of a self-ligating orthodontic bracket 100 according to one embodiment of the invention. The self-ligating orthodontic bracket 100 includes a mounting base 105 for attachment to a tooth surface, an archwire slot 110 formed in the mounting base 105 and sized to receive an orthodontic archwire (not shown), and a rotary ligating cover 115 (shown in a closed position) that retains the orthodontic archwire within the archwire slot 110. As will be discussed in more detail below, in one embodiment, the rotary ligating cover 115 comprises a plate (as shown) that is rotatable about an axial element (such as a retaining pin 120) that is eccentrically positioned (i.e., the pivot point is positioned on one side of the bracket 100) and has a pivot axis (as shown) that is perpendicular to the archwire slot 110 and substantially orthogonal to the tooth surface and the mounting base 105 coupled thereto. The rotary ligating cover 115 preferably includes one or more coplanar resilient retaining features (or locking mechanisms) 125 for retaining the rotary ligating cover 115 in a closed position to retain an orthodontic archwire within the archwire slot 110.

As shown in FIG. 1, the one or more coplanar resilient retention features 125 may comprise resilient portions of the rotary ligating cover 115 that are suitably formed to permit coplanar deflection and subsequent locking of one or more raised surfaces of the rotary ligating cover 115 with one or more corresponding indentations 130. Here, the resilient retention features 125 have been designed to deflect inwardly toward the axis of the retaining pin 120 for lockable engagement between one or more raised surfaces (or locking tabs) of the rotary ligating cover 115 and one or more cooperatively mating indentations 130. In this configuration, the resilient retention features 125 deflect in a direction coplanar with the rotary ligating cover 115 and engage the mating notches 130. Thus, forces applied perpendicular to the rotary ligating cover 115 (i.e., forces in the labial-lingual direction) that may occur as a result of movement of an archwire retained within the archwire slot 110 are less likely to affect retention of the archwire within the archwire slot 110. Thus, the self-ligating orthodontic bracket 100 more securely retains an archwire than other bracket designs.

Also shown in FIG. 1, the self-ligating orthodontic bracket 100 may include one or more orthodontic appliance features, such as an outer surface feature 145 of the rotary ligating cover 115. The outer surface features 145 may be raised ridges (as shown), recessed grooves (not shown), circular recessed areas, or any of numerous suitable shapes and configurations that may improve the ease of use of the bracket 100. For example, an orthodontic appliance such as a probe or scraper may be used with the outer surface feature 145 to rotatably open or close the rotary ligating cover 115 to expose or cover, respectively, the archwire slot 110. Also, pliers or another orthodontic appliance may be used with the outer surface feature 145 (possibly along with one side of the bracket 100) to close the rotary ligating cover 115. Additionally, the outer surface features 145, alone or in combination with the retaining pins 120 and other visual aspects of the bracket 100, preferably provide a centerline of the bracket 100 for assisting an orthodontist in placing the bracket 100 on a patient's tooth.

The self-ligating orthodontic bracket 100 preferably includes rounded edges and a chamfered archwire slot end 150 to improve comfort for the patient wearing the orthodontic appliance. As shown and as will be described in some of the figures herein, the rotary ligating cover 115, the outer frustoconical shape of the retaining pin 120, and other features that may define an outer surface of the bracket 100 opposite the mounting base 105, preferably include a smooth and rounded shape to enhance patient comfort and minimize the overall side profile or outer dimension of the bracket 100 from the bonding surface of the mounting base 105. Preferably, the outer surfaces of the one or more notches 130 and the adjacent edges 160 therebetween are coplanar and flush with the outer surface of the rotary ligating cover 115, and particularly with the outer surfaces of the one or more resilient retaining members 125 and the adjacent or adjacent outer surfaces therebetween.

FIG. 2 is an exploded isometric view of a self-ligating orthodontic bracket 200 having a bracket base 205, a rotary ligating cover 210, and a retaining pin 215, according to one embodiment of the invention. As shown, the rotary ligating cover 210 may be rotatably secured to the bracket base 205 using a retaining pin 215 inserted through a hole 220 in the rotary cover 210 and journaled into a corresponding hole 225 in a tie wing 230 formed on one side of an archwire slot 235. The outer surface 240 of the bracket 205, opposite the tooth mounting surface 245 and upon which the rotary ligating cover 210 may rotate when fastened to the bracket 205, preferably encompasses substantially all of the outwardly facing surface area of the tie wing 230, and the axis of rotation 250 of the rotary ligating cover 210 extends through the outer surface 240. The coplanar portions 255 of the opposing tie wings 260 on the other side of the archwire slot 235 receive the bottom surface of the rotary ligating cover 210 such that, in the closed position, the rotary ligating cover 210 covers a substantial portion of the archwire slot 235.

As will be described in further detail, the outer surface 240 preferably incorporates concentric circular recesses 265 and 270 for limiting rotation of the rotary ligating cover 210 due to asymmetry of the bracket 200. For example, for brackets 200 having the overall shape of a rhomboid or parallelogram when viewed from the bracket's outer surface toward the tooth mounting surface 245 (or a front view), the rotary ligating cover 210 need not be symmetrical about its centerline formed by the through-hole 220 and (as shown) the outer surface feature 275. For such an asymmetrical rotary ligating cover 210, the circular recess 265 may be used in combination with the engagement of the locking tab 280 and the cooperatively mating cutout portion or indentation 285 to create a closed position for the rotary ligating cover 210 when the rotary ligating cover 210 is rotated in a clockwise direction about the axis of rotation 250 as viewed from the outer surface of the bracket 200 toward the tooth mounting surface 245. As will be shown in subsequent views, the rotary ligating cover 210 may incorporate protruding nubs on its lower surface that ride within the concentric circular recesses 265 and 270.

In the embodiment shown in FIG. 2, the rotary ligating cover 210 can be closed to cover the archwire slot 235 by rotating the rotary ligating cover 210 in a clockwise direction until the locking tab 280 engages a cooperatively mating notch 285 formed on the tie wing 260 and a protruding nub (not shown) reaches the end of (or just beyond) the circular recess 265. The rotary ligating cover 210 can be opened to expose the archwire slot 235 by rotating the rotary ligating cover 210 in a counterclockwise direction so that the protruding nub moves first within the circular recess 265 and then within the circular recess 270 until the archwire slot 235 is fully exposed.

Next, FIG. 3 is an exemplary front view of a self-ligating orthodontic bracket 300 engaged with an archwire 310. The bracket 300 may be mounted to the labial (front) surface of a tooth as part of a typical bracket system. Alternatively, the bracket 300 can be mounted to the lingual (back) surface of the tooth as part of a lingual or "hidden" bracket system. As will be discussed further, the front profile of the bracket 300 may be designed for use on a particular tooth surface. For example, the bracket 300 may be designed with a particular rhomboid or parallelogram profile for bonding to a particular tooth, such as one of the upper or lower central, lateral, cuspid, bicuspid, molar, and the like.

The archwire 310 may be retained within the self-ligating bracket 300 such that the archwire 310 extends in a mesial-distal orientation parallel to the occlusal surfaces (the cutting or incising edges) of the teeth. Other orientations may be used with the bracket 300. However, this orientation is typical for straight wire arch (or Roth) appliances, whereby the crown angle and crown inclination are designed into the bracket 300, thereby allowing the use of archwires that are "straight" or parallel to the cut surface of each tooth (when the teeth are positioned in proper orthodontic alignment). The crown angle is the approximate mesial-distal to gingival-occlusal orientation of the tooth and is affected by the mesial-distal orientation of the archwire slot (or slot inclination). Crown rake is the approximate labial-lingual to gingival-occlusal orientation of the tooth and is affected by the rotational orientation of the archwire slot (or slot torque) along the mesial-distal (or archwire) axis.

The bracket 300 shown in FIG. 3 has a designed slot tip 320, which is the angular offset between the centerline 325 of the bracket 300 and a line perpendicular to a mesial-distal line parallel to the archwire 310. In orthodontic practice, the bracket 300 may be bonded to the tooth surface such that the centerline 325 of the bracket 300 is aligned with the gingival-occlusal axis (or long axis) of the clinical crown of the tooth.

Although straight wire appliances typically include individually designed brackets, each bracket having a desired crown inclination (socket torque) and crown angle (socket inclination) for a particular tooth, other techniques requiring different orientations may be used. For example, standard edgewise appliances typically include brackets having a rectangular profile, and the brackets are oriented such that the center line of the bracket is aligned along the gingival-occlusal axis (or long axis) of the clinical crown and perpendicular to the archwire slot. Typically, the brackets of standard edgewise appliances have archwire slots that are not parallel to the incisal edges of the teeth (when the teeth are positioned in proper orthodontic alignment). Rather, the archwire is angled, bent and twisted to define the desired position of the teeth.

As is commonly practiced in orthodontic treatment, brackets can be manufactured by prescription for a particular patient. The bracket may be designed to include the appropriate slot torque and slot inclination for each individual tooth of a particular patient. For example, specifically designed brackets may be manufactured for the upper left center, upper left side, upper left cuspid, etc., moving distally toward the upper left molars (individual teeth are indicated using Palmer notation). Each bracket typically incorporates a specific slot torque and slot rake, as well as other features as needed. For example, the bracket for the upper left cuspid may include a slot inclination 320 of perhaps 9 ° and include a ball hook 330 for use with the resilient or other components of the orthodontic appliance.

Still referring to FIG. 3, the mounting base 315 of the bracket 300 can be sized to fit a particular tooth surface. For example, the mounting base 315 may be wider at the cutting end of the tooth to match the shape of the tooth surface. The bracket 300 may be bonded to a tooth surface or alternatively to a strap assembly attached to the tooth. The bracket 300 is oriented such that the rotary ligating cover 335 pivots about an axial element 340, the axial element 340 being positioned on the tie wing on the side of the archwire slot closest to the tooth surface cutting end (and opposite the gingival end). However, the bracket may be positioned instead such that the rotary ligating cover 335 pivots about the axial element 340 positioned on the gingival side of the archwire slot.

For the particular bracket 300 shown in FIG. 3, the rotary ligating cover 335 follows the general rhomboid or parallelogram shape of the bracket 300 and is not symmetrical about its centerline 325. A protruding nub or rotation stop 345 may be formed on the underside of the rotary ligating cover 335 designed to ride within the concentric circular recesses 350 and 355 as the rotary ligating cover 335 pivots about the axial member 340. For example, as the rotary ligating cover 335 is rotated in a counterclockwise direction from the closed position shown, the rotation stop 345 slides into the first circular recess 350 and advances, and upon further rotation, freely advances within the second circular recess 355. Likewise, when the rotary ligating cover 335 is rotated in a clockwise (or closing) direction, the rotation stop 345 is free to advance within the second circular recess 355 and then within the first circular recess 350 until sliding upwardly and slightly beyond the end of the first circular recess 350.

As the rotary ligating cover 335 is rotated in a clockwise direction about the axial member 340, the resilient retaining feature (or mechanism) 360 deflects inwardly toward the axial member 340 until the locking tab 365 engages the cooperatively mating cutout portion (or notch) 370. In the illustrated embodiment, the resilient retention members 360 resemble coplanar fingers within the rotary ligating cover 335, whereby the release channels 375 permit flexing of at least the portion of the resilient retention members 360 adjacent to the locking tabs 365.

As will be appreciated, in one embodiment, the orientation of the concentric circular recesses 350 and 355 and the associated rotation stop 345 may be reversed such that the rotary ligating cover 335 may be opened in a clockwise direction of rotation and closed in a counterclockwise direction of rotation. Likewise, the positions of the locking tabs 365 and corresponding indentations 370 may be reversed, according to one embodiment, while still providing the intended function. The bracket 300 may include one or more locking tabs (such as locking tab 365) that are aligned in coplanar relationship with the rotary ligating cover 335 and cooperatively mate with cutout portions in the rotary ligating cover. In other words, the one or more locking tabs may be formed on the bracket base, and cooperatively mating cutout portions into which the locking tabs engage when the ligating cover is in the closed position may be formed on the rotary ligating cover.

Next, FIG. 4 is a cross-sectional view of a self-ligating orthodontic bracket 400 with a rotary ligating cover 405 in a closed position (e.g., through centerline 325 in FIG. 3), according to one embodiment. The bracket 400 includes a mounting base 410 and a pair of tie wings 415 and 420 formed thereon and extending away from the mounting base 410 and defining an archwire slot 425 therebetween. The archwire slot 425 is sized to receive an orthodontic archwire 430 and the rotary ligating cover 405 is selectively rotatable between a closed position (as shown) for securely retaining the archwire 430 within the archwire slot 425 and an open position (not shown) for allowing access to the archwire slot 420. The rotary ligating cover 405 may be rotated about an axial element, such as a retaining pin 435, positioned on one side of the bracket 400, such as one of the tie wings 420. The retaining pin 435 is shown to incorporate a conical frustum extending across the outer surface of the rotary ligating cover 405 and a lower portion that is journaled or otherwise securely attached in a receiving hole or recessed area in the tie wing 420. As shown, the retaining pin 435 can be sized with a smaller diameter that is inserted into a receiving hole in the tie wing 420 and a larger diameter about which the rotary ligating cover 405 may be slidably rotated. According to one embodiment, the smaller diameter allows for a press-fit operation for retaining the rotary ligating cover 405 to the bracket 400, whereby the smaller diameter of the retaining pin (or dowel pin) 435 is forcibly pressed into a receiving hole in the tie wing 420. However, other configurations may be used. For example, a retaining pin having a single diameter may be used, possibly with precision fastening provisions to ensure that the retaining pin can rotate freely about the retaining pin.

The pair of tie wings (415 and 420 as shown) extend generally transverse to the archwire slot 425, with one tie wing (i.e., 415) extending from the archwire slot 425 in the gingival direction and the other (i.e., 420) extending from the archwire slot 425 in the occlusal direction. Tie wings 415 and 420 provide additional utility and flexibility to the orthodontist in situations where it is desirable to use standard elastic bandages or other attachments that require tie wings. The use of standard elastic bandages creates friction between the archwire and the elastic bandage. Frictional, or active engagement with the archwire 430 allows additional force to be applied to the tooth surface 440 bonded to the bracket 400. For example, the movable engagement with the archwire 430 can be used to urge tooth movement (to increase or decrease the spacing between adjacent teeth) along the intermediate distal (or archwire) axis. The active engagement with the archwire 430 can also be used to increase the force applied to change the crown angle (affected by slot rake) and crown rake (affected by slot torque).

Instead, the self-ligating bracket 400 may rely on passive engagement with the archwire 430. Under passive engagement, the archwire 430 is not constrained within the archwire slot 425 and is instead permitted to move within the archwire slot 425. Such brackets may include passive or so-called frictionless bracket systems and do not require conventional bandages or ligating modules. In this system, the archwire slot 430 is free to slide within the archwire slot 425 along the medial distal axis.

As previously discussed, crown rake is generally the labial-lingual to gingival-occlusal orientation of the tooth and is affected by the direction of rotation of the archwire slot 430 along the medial distal axis. An axial (cross-sectional) view of the bracket 400 along the medial distal axis is shown in FIG. 4. Here, the archwire slot 425 is shown as being slightly angled (or rotated) so that the labial-lingual side (orthogonal to the rotary ligating cover 405) of the archwire slot 425 is not perpendicular (or not orthogonal) to the tooth surface 440. This is a typical rotational orientation for archwire slots used in straight wire appliances where slot torque is designed into the brackets. In contrast, standard edgewise appliances typically include archwire slots that are laterally perpendicular to the mounting surfaces of the teeth.

Turning now to FIGS. 5A-5C, cross-sectional views are provided showing the rotary ligating cover 335 in a closed and partially open position on the bracket base 315 (or tie wing 500 thereon), according to various embodiments of the invention. FIG. 5A is a cross-sectional view as shown in FIG. 3 and shows the rotary ligating cover 335 in a closed position with the rotation stop 345 slightly beyond the circular recess 350. The slight spacing 505 between the mating surfaces of the rotary ligating cover 335 and the tie wing 500 may provide additional retaining force for retaining the rotary ligating cover 335 in the closed position. For example, the frictional forces between the rotation stop 345 and the outer surface of the tie wing 500, as well as the frictional forces involved in retaining the axial member (not shown) of the rotary ligating cover 335, can provide additional retention beyond that provided by engagement of other locking features associated with the rotary ligating cover 335, such as, for example, coplanar locking keys along the edge surfaces of the ligating cover 335.

FIG. 5B is a cross-sectional view as in FIG. 5A with the rotary ligating cover 335 in a partially open position and the rotation stop 345 is shown traveling in the circular recess 350. Here, the rotary ligating cover 335 has been partially opened (in a counterclockwise direction), whereby the rotation stop 345 falls into the circular recess 350.

FIG. 5C shows the rotary ligating cover 335 in a closed position, as a cross-sectional view like FIG. 5A, and a rotation stop 345 is formed on a lower surface of the ligating cover 335 and positioned outside or beyond an end of the circular recess 350, according to one embodiment. However, the rotation stop 345 in FIG. 5C is shown seated within a cooperatively mating cutout portion or detent 510 of the outer surface of the tie wing 500 and, thus, holds the rotary ligating cover 335 in the closed position. In operation, as the ligating cover 335 is rotated, the rotation stop 345 may enter the circular recess (or recess channel) 350, as shown in FIG. 5B, straddle the bracket material 515 at the end of the circular recess 350, and seat in the detent 510.

FIG. 6 is a top view of a self-ligating orthodontic bracket with a rotary ligating cover 335 in a partially open position, according to one embodiment of the invention. When the rotary ligating cover 335 is opened (rotating the cover 335 in a counterclockwise direction), in one embodiment, the rotation stop 345 clears the circular recess 350. Also shown in fig. 6, according to one embodiment, is the relative position of the locking tabs 365 and their cooperatively mating cut-out portions (or indentations) 370. As the rotary ligating cover 335 is opened, pivoting about the axial member 340, the locking tabs 365 clear their respective notches 370, allowing the rotary ligating cover 355 to rotate more freely.

FIG. 7 is a top view of a self-ligating orthodontic bracket as in FIG. 6, except with the rotary ligating cover 335 in an open position, exposing an archwire slot 700 formed in the bracket base 315, according to one embodiment. Here, the rotary ligating cover 335 has been rotated in a counterclockwise direction until the archwire slot 700 is fully exposed. By this portion of the rotation, the rotation stop 345 has traveled within the circular recess 355. In one embodiment, the rotation stop 345 is moved upward against an end (not shown) in the circular recess 355 to stop counterclockwise rotation of the rotary ligating cover 355 when the archwire slot 700 is fully exposed.

As will be appreciated, variations of the self-ligating orthodontic brackets described herein are apparent. For example, FIG. 8 shows a top view of a rotary ligating cover 800 according to an alternative embodiment of the invention. The rotary ligating cover 800 incorporates a relief area 805 cut out behind the locking key 810, leaving a resilient retaining feature 815 that is deflected inwardly in a direction coplanar with the rotary ligating cover and toward an axial member 820 about which the rotary ligating cover may pivot. For example, as the rotary ligating cover 820 is rotated into a closed position, the resilient retaining features 815 deflect inwardly in a direction perpendicular to the pivot axis of the axial member 815, allowing the locking key 810 to engage a cooperatively mating cutout portion or indentation (not shown) in the bracket base.

FIG. 9 is a top view of a rotary ligating cover 900 according to another embodiment of the invention. The rotary ligating cover 900 incorporates one or more locking tabs 905 that engage cooperatively mating cutout portions or indentations (not shown) in the bracket base when the rotary ligating cover 900 is rotated into a closed position. The one or more locking tabs 905 are preferably aligned in a coplanar relationship with the rotary ligating cover 900 as shown, cooperatively mate with a cutout portion in the bracket base (not shown), and are capable of exerting a retaining force in a direction coplanar with the rotary ligating cover and, thus, retaining the rotary ligating cover in a closed position.

FIG. 10 is a cross-sectional view (along its centerline as in FIG. 4) of a self-ligating orthodontic bracket 1000 with a rotary ligating cover 1005 in a closed position, according to an alternative embodiment of the invention. Similar to the bracket shown in FIG. 4, the bracket 1000 includes a mounting base 1010 for mounting the bracket on a tooth surface 1040, and a pair of tie wings 1015 and 1020 formed on the mounting base 1010, extending outwardly therefrom and defining an archwire slot 1025 therebetween. The rotary ligating cover 1005 is rotatably secured to one of the tie wings 1020 and is capable of rotatably and securely enclosing the archwire slot 1025 and an archwire 1030 therein. However, the rotary ligating cover 1005 may be rotatably secured using a retaining pin 1035 that fits into a bushing 1045 formed on the tie wing 1020. The retaining pin 1035 may be any fastener having a frustoconical head or similar head structure capable of retaining the rotary ligating cover 1005 by overlapping the outer surface of the bushing 1045 and a portion of the outer surface of the rotary ligating cover 1005 extending outwardly from the bushing 1045. In one embodiment, the retaining pin 1035 includes one or more axial ribs 1050 to improve the interference fit and retention of the retaining pin 1035 within the bushing 1045 and the hole or recess extending below the bushing 1045 toward the bracket mounting base 1010.

FIG. 11 is a cross-sectional view (along its centerline as in FIG. 4) of a self-ligating orthodontic bracket 1100 with a rotary ligating cover 1205 in a closed position according to another alternative embodiment of the invention. Similar to the bracket shown in FIG. 4, the bracket 1100 includes a mounting base 1110 for mounting the bracket 1100 on a tooth surface 1140 and a pair of tie wings 1115 and 1120 formed on the mounting base 1110, extending outwardly therefrom and defining an archwire slot 1125 therebetween. The rotary ligating cover 1105 is rotatably secured to one of the tie wings 1120 and is capable of rotatably and securely enclosing the archwire slot 1125 and an archwire 1130 therein. However, the rotary ligating cover 1105 may be rotatably fastened about a pole 1135 formed on the tie wing 1120 and molded (or umbrella-shaped) to retain the rotary ligating cover 1105. Fig. 11 shows a cross-sectional view before embossing. During the coining operation, some of the material comprising the stem stake 1135 is displaced inwardly toward the bracket mounting base 1110 and radially outwardly from the stem stake 1135 to overlap the annular portion 1145 of the outer surface of the rotary ligating cover 1005 immediately adjacent the stem stake 1135. To facilitate the coining operation and to improve the repeatability and consistency of the overlap of the ring portion 1145 of the rotary ligating cover 1105, a recess, such as a conical recess 1150, may be formed on the outward facing surface of the stud 1135 (as shown). Likewise, other location lines or recessed areas may be included as desired depending on the particular embossing process and the material selected for the bracket 1100.

FIG. 12 is a top view of a self-ligating bracket base 1200 with lead-in bevels 1205, 1210, 1215, and 1220 on the archwire slot 1225, according to one embodiment of the invention. Lead-in chamfers may be provided to improve the ease of insertion of the archwire into the archwire slot 1225 and adjustment within the slot. Each lead-in chamfer includes beveled edges to obtain a widened and tapered surface leading into the (narrower) archwire slot. The lead-in chamfer may be on one or both ends of the archwire slot 1225. For example, the lead-in chamfers 1205 and 1210 may be included on the distal end of the archwire slot 1225 having a medial distal axis. Additional lead-in bevels 1215 and 1220 may be included on the other end (e.g., the middle end) of the archwire slot 1225. However, the archwire slot 1225 can incorporate any one or any combination of more than one (or none) lead-in bevels 1205, 1210, 1215, and 1220.

Archwire 1225 preferably includes bevels on both ends, such as lead-in bevels 1205 and 1210 on one end and 1215 and 1220 on the other end. As shown, the lead-in chamfer 1205 may be oriented on one gingival-occlusal opening edge of the archwire slot 1225 and the lead-in chamfer 1210 may be oriented on the opposite gingival-occlusal opening edge. Likewise, the lead-in chamfer 1215 may be oriented on one gingival-occlusal opening edge on the opposite end of the archwire slot 1225, and the lead-in chamfer 1220 may be oriented on the opposite gingival-occlusal opening edge. Although not shown in fig. 12, a lead-in chamfer on the labial-lingual opening edge of the archwire slot 1225 may be included.

Also shown in FIG. 12 is a recessed area within the self-ligating bracket base 1200 sized to receive a rotation stop or protruding nub formed on the lower surface of a rotary ligating cover (not shown), according to one embodiment. As with the other cooperatively mating components described herein, the positions of the one or more recessed areas and the cooperatively mating one or more rotational stops can be reversed. For example, a rotation stop may be formed on the bracket base 1200 and a recessed area sized to receive the rotation stop may be formed on the lower surface of the rotary ligating cover. To facilitate a concise description of the operation of the various embodiments, a recessed region is shown formed on the outer surface of the bracket base 1200. The cross-sectional view in these areas of the bracket may be similar to the cross-sectional view shown in FIG. 5C. That is, the self-ligating bracket base 1200 may include a concentric circular recess 350 formed on an outer surface of the bracket base within which a rotation stop formed on a lower surface of the rotary ligating cover may travel as the rotary ligating cover rotates. In operation, as the rotary ligating cover is rotated (e.g., in a clockwise direction), the rotation stop may enter the circular recess 350, ride over the bracket material 515 at the end of the circular recess 350, and seat within the detent 510, thereby retaining the rotary ligating cover in a particular position (either open, exposing the archwire slot 1225, or closed, covering the archwire slot 1225).

In one embodiment, the self-ligating bracket base 1200 includes a second concentric circular recess 1240 formed in the bracket base within which the rotational stop may travel as the rotary ligating cover is rotated. Upon rotation of the rotary ligating cover (e.g., in a counterclockwise direction), the rotation stop may enter the circular recess 1240, ride over the bracket material 1235 at the end of the circular recess 1240, and seat within the detent 1230, thereby retaining the rotary ligating cover in a particular (open or closed) position.

The position of the rotation stop formed on the lower surface of the rotary ligating cover may be oriented to determine the direction of rotation, according to one embodiment, for exposing or covering the archwire slot 1225. All brackets in a particular prescription of brackets may be configured to open (to expose the archwire thereunder) using the same directional rotation (such as counterclockwise) of the rotary ligating cover, for example. Alternatively, some brackets may be configured to open with a counterclockwise rotation and others with a clockwise rotation. For example, if it is desired to mount the brackets on the tooth such that each bracket has an axis of rotation (such as axis of rotation 250 shown in fig. 2) positioned on the occlusal side of the archwire slot, and if it is desired to configure the brackets such that the archwire is exposed by applying pressure in a mesial direction (i.e., directly toward the anterior teeth or center). Each bracket may be configured to open in either a clockwise or counterclockwise direction depending on the bracket's intended position in the mouth. In this example, the orthodontist may open each bracket by placing an orthodontic appliance on the distal edge of the bracket's rotary ligating cover and applying pressure in a medial direction. For brackets mounted on teeth in the upper left or lower right (Palmer) quadrant, the rotary ligating cover for each bracket will be opened by rotating the cover in a counterclockwise direction. For brackets mounted on teeth in the upper right or lower left quadrant, the rotary ligating cover of each bracket will be opened by rotating the cover in a clockwise direction.

Assuming, for example, that the bracket in FIG. 12 is configured such that the rotary ligating cover may be opened by rotating the cover in a counterclockwise direction to expose the archwire slot 1225, a rotation stop formed on a lower surface of the rotary ligating cover may be positioned such that it seats within the brake 510 when the rotary ligating cover closes the archwire slot 1225. As the rotary ligating cover is rotated counterclockwise, the rotary stop (such as rotary stop 345 in FIG. 5C) moves from its seated position within the brake 510, rides over the bracket material 515 between the brake 510 and the end of the circular recess 350, and then travels within the circular recess 350 until moving freely in space until entering the circular recess 1240 on the other side of the bracket base 1200. As the rotary ligating cover continues its counterclockwise rotation, the rotational stop rides over the bracket material 1235 and begins to seat within the detent 1230 beyond the end of the circular recess 1240. The detent 1230 may be positioned so as to hold the rotary ligating cover in an open position, fully exposing the archwire slot 1225.

FIG. 13 is a top view of a self-ligating bracket 1300 having cutouts 1305, 1310 on the sides of a rotating cover 1315, according to one embodiment of the invention. As shown, a pair of cutouts 1305, 1310 (each oriented transversely to the archwire 1225) in the rotary ligating cover 1315 provide for manipulation of the rotary ligating cover 1315 to expose or cover the archwire slot 1225 thereunder. For example, if the rotary ligating cover 1315 were to be opened to expose the archwire slot 1225 by rotating the cover 1315 in a counterclockwise direction about the axial member 1320, an orthodontic tool may be used to apply pressure on the cutout 1310 in a direction parallel to the archwire slot 1225 toward the cutout 1305 at the opposite end of the archwire slot 1225. In a similar manner for this example, the rotary ligating cover 1315 is closed to cover the archwire slot 1225 by using an orthodontic tool to apply pressure on the cutout 1305 to rotate the cover 1315 in a clockwise direction about the axial member 1320. As previously described, the direction of rotation in opening and closing the rotary ligating cover 1315 may be reversed.

The self-ligating orthodontic brackets described herein may include any of a wide variety of aesthetics suitable for use in an orthodontic appliance. For example, the brackets may include a prescription of brackets with each individual bracket having multiple colors, adjacent brackets having different colors, or groups of brackets having different colors. The brackets may be opaque or translucent or a combination thereof. For example, the bracket base 1325 in FIG. 13 may be opaque (or a particular color), and the rotary ligating cover 1315 may be translucent. Or, as another example, the bracket 1300 may have a base 1325 and a rotary ligating cover 1315 of the same color, with one of the cutouts (such as cutout 1310) marked with a different color as a visual aid to indicate which of the cutouts 1305, 1310 to use when opening the rotary ligating cover 1315 to expose the archwire slot 1225 therebelow. Or, as yet another example, the bracket base 205 in FIG. 2 may be the same color as the rotary ligating cover 210, and the retaining pin 215 may be a different color to facilitate placement of the bracket 200 on a tooth and subsequent manipulation of the rotary ligating cover 210. Numerous other variations involving the use of different colors are possible.

The self-ligating orthodontic brackets described herein may comprise any of a wide variety of materials suitable for use in orthodontic appliances. These materials typically include plastics, ceramics, stainless steel, titanium, or other metal alloys. The bracket preferably comprises a biocompatible material having anti-corrosive properties, and the bracket preferably comprises a material that can be formed into the illustrated configuration, yet still retain suitable strength characteristics for retaining commonly used orthodontic archwires or other components of orthodontic appliances.

Nickel may be the most common metal associated with contact dermatitis in orthodontics. Recent figures show that perhaps 10% of patients are sensitive to nickel. However, metal alloys containing nickel, such as nickel titanium and stainless steel, are widely used in orthodontic appliances. Nitinol may have a nickel content of greater than 50% and may potentially release sufficient nickel in the oral environment to cause an allergic reaction to occur. Stainless steel has a much lower nickel content, perhaps about 8%, and nickel is less reactive because it is confined within the lattice of stainless steel. Thus, stainless steel orthodontic components are less likely to cause nickel hypersensitivity.

However, due to other uncertainties regarding the sensitivity of a particular patient to nickel, it may be desirable to provide nickel-free orthodontic brackets to avoid nickel hypersensitivity altogether. Thus, the self-ligating orthodontic brackets described herein preferably comprise a nickel-free material. In one embodiment, the bracket comprises a nickel-cobalt-free chromium alloy.

Several methods may be used to manufacture the self-ligating orthodontic brackets described herein. For example, the brackets can be cast, machined, injection molded, and the like. Injection molding of the plastic may be Ceramic Injection Molding (CIM) or Metal Injection Molding (MIM) depending on the material selected. The bracket may include a molded base in combination with a molded rotary ligating cover that is coined to retain the cover to the bracket, or the bracket may include a molded base in combination with a molded ligating cover that is secured to the bracket using a separate axial member press fit onto the bracket. For example, the bracket may comprise an assembly of a shaped bracket body and a shaped rotary ligating cover that is retained on the tie wings of the bracket body after a coining operation whereby posts projecting from the bracket body are umbrella shaped or coined to retain the rotary retaining cover thereon. The ball hook, or other component, may be welded to the bracket assembly or formed as part of the bracket body (i.e., as part of the molded bracket body).

The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.

Claims (6)

1. A self-ligating orthodontic bracket, comprising:

a) a mounting base for attachment to a tooth surface;

b) an archwire slot formed on the base and sized to receive an orthodontic archwire;

c) a rotary ligating cover selectively rotatable about an axial element between an open position allowing access to said archwire slot and a closed position covering said archwire slot, said axial element having an axis of rotation oriented perpendicular to said archwire slot and orthogonal to said tooth surfaces; and

d) one or more locking keys disposed on said rotary ligating cover for retaining said rotary ligating cover in a closed position, said one or more locking keys aligned in a coplanar relationship with said rotary ligating cover, said one or more locking keys oriented across said archwire slot from said axis of rotation when said rotary ligating cover is in said closed position,

e) wherein the one or more locking keys comprise a resilient portion of the rotary ligating cover adapted to flex inwardly toward the axis of rotation and having a raised surface engageable with a recess in the mounting base.

2. The bracket of claim 1, further comprising a pair of tie wings extending from the base, and the archwire slot is defined between the tie wings.

3. The bracket of claim 2, wherein the rotary ligating cover is rotatable about an axial element, the axial element including a retaining pin insertable into a hole in the base for rotatably securing the rotary ligating cover to the base, the hole being sized for receiving the retaining pin.

4. The bracket of claim 3, further comprising a bushing formed on the base.

5. The bracket of claim 2, wherein the axial element includes a post formed on the base and coined to rotatably secure the rotary ligating cover to the base.

6. The bracket of claim 1, wherein said resilient portion of said rotary ligating cover includes a channel journalled inwardly of said locking key within said rotary ligating cover to permit said locking key to flex toward said axis of rotation.