ALIGNABLE, SELF-LIGATING ORTHODONTIC BRACKETS

Abstract: An alignable self-ligating orthodontic bracket (5) which includes a base (10) for attachment to a tooth bonding pad (50) and transversely spaced tying lugs (12) that project from the base (10). The bracket (5) defines an anterior surface (17) interrupted by an archwire slot (18). A slide (21) mounted on the bracket (5) includes a movable roof (24) that slides over and covers the archwire slot (18) to retain an archwire therein. The slide (21) is supported on the bracket (5) by a pair of runners (22) that slidably engages ledges (23) formed in opposed side surfaces (15) of the bracket (5). The roof (24) of the slide (21) is connected to the runners (22) by two legs (30) that straddle the main body (10) of the bracket (5). The legs (30) are bent downwardly inward to bias the runners (22) into contact with their respective ledges (23). Preferably, the edge (25') of the inner surface (25) of each runner (22) is rounded to reduce sharp edge contact between the runner (22) and the bracket body (10). This reduces sticking and particle generation. Additionally, leading ends (22') of the runners (22) are preferably rounded (22'') thus making easier the process of engaging the runners (22) to the ledges (23). The bracket (5) is mounted on a bonding pad (50), the bonding pad (50) preferably having two parallel edges and a pointed third edge. The parallel edges and the pointed edge facilitate alignment when the pad (50) and bracket (5) are being attached to a tooth.

Description: ALIGNABLE, SELF LIGATING ORTHODONTIC BRACKETS TECHNICAL FIELD This invention relates to improvements devices used in orthodontic treatment and, more particularly, to alignable, self ligating orthodontic brackets. BACKGROUND OF THE INVENTION Brackets are often attached to a patient's teeth in orthodontic treatment. These brackets are engaged by a resilient archwire that exerts forces on them. The brackets are bonded to the patient's teeth, so forces applied to the brackets by the archwire are transferred to the teeth to move them. To provide appropriate force transfer, each bracket includes a slot which receives the archwire. Although this method of treatment works very well, retaining the archwire in the slot has been a recurring problem associated with the brackets described above. In an attempt to facilitate archwire retention, many brackets include projections. These projections facilitate holding down the archwire within the slot by means of wires (ligatures) or elastomeric O-rings. Unfortunately, installing archwires with ligatures or O-rings is time-consuming and less than ideal. This is particularly so as orthodontic brackets get smaller. Accordingly, numerous attempts have been made to design brackets that are self ligating and much has been written on the subject. A detailed discussion, for example, of various self ligating orthodontic brackets can be found in US 5,094,614, issued to Wildman. As recognized in this Wildman patent, a self ligating bracket requires a lockable closure for the archwire slot. Also, as discussed in Wildman, the closure should ideally leave the top and bottom of the bracket, including the projections conventionally used for anchoring ligatures, free to receive other attachments or auxiliary devices. The Wildman patent, in an attempt to address these issues, discloses a slidable closure that engages the front of the archwire. The closure is recessed from the front surfaces of the bracket. Unfortunately this recessed closure requires the archwire to be fully recessed within the slot before the closure can be moved into place over the archwire. Given the small size of orthodontic brackets, this arrangement makes it difficult to confirm visually that the archwire is properly seated within the slot. In contrast, in a conventional bracket with ligatures, proper seating of the archwire can be confirmed by noting visually that the front surface of the archwire is flush with the front surface of the bracket. It is, therefore, desirable that a self ligating bracket provide similar visual reference capabilities to the user. As described above, this cannot be attained in brackets such as disclosed in the Wildman patent. The Wildman bracket, accordingly, does not provide an appropriate solution. An attempt to so is demonstrated in the patents issued to D wight H. Damon. Of these patents, US 5,466,151 is a good example. This patent discloses a self ligating orthodontic bracket in which the archwire slot is closed by a sliding closure mounted on the bracket. The closure overlaps and partially covers an anterior surface of the bracket and is supported by slides that engage opposed side surfaces of the tying lugs or the bracket body. A transverse flat spring is recessed in a cavity in the main body of the bracket. This spring selectively engages cut outs on the posterior surface of the closure and, in so doing, holds the closure in an open or a closed position relative to the archwire slot. This bracket has a number of advantages. The sliding closure is desirable because it reduces the time required for opening and closing the archwire slot during periodic adjustment of the archwire and brackets. Further, the bracket is designed to mount an archwire flush with its anterior surface. This facilitates visual positioriing of the archwire during orthodontic treatment. In addition, the sliding closure is permanently retained on the bracket during use, whether left open or closed. This guards against accidental release of the closure while the bracket is worn on a tooth. Finally, the bracket includes the usual tying extensions and the closure leaves these fully accessible to other orthodontic attachments. Unfortunately, for all its advantages, the Damon bracket has certain disadvantages: First, the slides of the closure are engaged by guides along the full length and across the full width of each slides. This is disadvantageous as a substantial amount of metal to metal contact exists. This contact increases the friction between the slides and the bracket body and makes the closure difficult to open and shut. Second, any particles generated between a slide and the bracket body, especially when the bracket is used for the first time, can be trapped between the slide and the body causing jamming of the closure. Third, and very importantly, as illustrated in Figures 27 and 28 of the Damon '151 patent, the bracket is mounted on a square pad for bonding to a tooth. Square pads, as described in US 4,415,330 (Daisley, et al.), have the disadvantage that they are difficult to align on the tooth for a self-ligating bracket. Certain prior art patents purport to include features which facilitate alignment of the bracket on the tooth. One such patent, US 4,415,330, discloses a bracket having a rhomboidal configuration which has edges that align, for example, with the occlusal edge and the crown long axis of the tooth. The tie wings/projections of the brackets have edges parallel to the crown long axis to assist in alignment during mounting of the bracket. In a different attempt to address this alignment issue, US 5,022,854 to Broughton et al. discloses a bracket with a trapezoidal configuration. The Daisley and Broughton patents go a long way to addressing the issue of aligning orthodontic brackets. But, they do not teach or even suggest self ligating brackets. Also, both suggest complex bracket body shapes and configurations. These configurations are, however, more complicated to manufacture accurately than the regular square bracket. Also the bracket disclosed in Broughton et al., is very difficult to use with the slide based self ligating bracket configurations described previously. The slides and the locking mechanisms are effectively incompatible with the trapezoidal non-regular geometry. Finally, as is apparent from the above description, the time and ease of installation is a significant consideration in the design and choice of brackets. Orthodontists, wishing to maximize the number of patients whose needs they address, must decrease the length of time any given patient spends in their offices. If a bracket is to address this need, therefore, it must be easy and quick to align on the tooth as well as be configured to quickly receive and retain an archwire. Accordingly, given the requirement for ease and speed of bracket use, there is a need for improving the sliding closures in self ligating brackets as well as for making such self ligating brackets easy to mount onto a patient's teeth. SUMMARY OF THE INVENTION Briefly, therefore, this invention provides for a self-locking orthodontic bracket which includes a base for attachment to a tooth bonding pad and transversely spaced tying lugs that project from the base. The bracket defines an anterior surface interrupted by an archwire slot. A slide mounted on the bracket includes a movable roof that slides over and covers the archwire slot to retain an archwire therein. The slide is supported on the bracket by a pair of runners that slidably engages ledges formed in opposed side surfaces of the bracket. The roof of the slide is connected to the runners by two legs which straddle the main body of the bracket. The legs are bent downwardly inward to bias runners of the slide into contact with ledges and/or the outside surfaces of the bracket. An inner acute angle formed between a runner and corresponding leg is preferably about 83° to 85°. Each ledge also defines an included acute angle, preferably one to four degrees less than the runner-leg angle of the slide, so that when the slide is positioned on the bracket body the metal-to-metal contact between the ledge/outer surface of the bracket and the runners of the slide is minimized. Though not necessary, the engaging surfaces of the ledge contacting edge of each runner are preferably chamfered (i.e., rounded) to reduce sharp edge contact between the runner and the bracket body. This reduces sticking and particle generation. In an alternative embodiment, a semi-circular cutout can be formed in the engaging surface of each runner. Particles generated between the runners and the bracket body ledges can then fall through the cutout. The bracket is preferably mounted on a generally parallelogram-shaped tooth bonding pad such that its axis peφendicular to the archwire slot is at an angle y relative to one of the pairs of the edges of the bonding pad. The angle γ is variable and is typically selected based on the idealized angle ω of the long axis of the tooth to be treated with respect to the occlusal plane of the mouth. The pad may also include score marks and other formations at its upper and lower edges to assist in pad alignment with the tooth axis. Other features and the advantages of this invention will become more apparent from the detailed description below and with reference to the accompanying drawings in which: BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cut away elevational view of an assembled bracket with the slide in a closed position; FIG. 2 is a cross-sectional perspective view of the body of the bracket of FIG. 1 with the slide removed. FIG. 3 is a side view of the bracket in FIG. 1; FIG. 4 is a side view of the bracket in FIG. 1 with the slide in an open position; FIG. 5 is a top perspective view of the slide for the bracket according to the invention; FIG. 6 is a partially cut-away, top view of the slide of FIG. 5; FIG. 7 is a partially cut-away, elevational view of the slide of FIG. 5; FIG. 8 is a sectional view of the slide taken along line 8-8 in FIG. 6; FIG. 9 is an elevational view of a spring suitable for use with the bracket of the invention; FIG. 10 is a sectional view of a fully assembled bracket taken along line 10-10 in FIG. 1; FIG. 11 is a sectional view similar to FIG. 10 , but showing the slide in an open position; FIG. 12 is a sectional view taken along line 12-12 in FIG. 3; FIGS. 13 is a plan view of the bracket (in outline) positioned on a non- square bonding pad according to the invention; FIG. 14 is a perspective view of the bracket mounted on a bonding pad for mounting to an upper tooth. FIG. 15 is a schematic illustration of the use of the bracket and pad combination of the invention during alignment and positioning on a tooth. DETAILED DESCRIPTION OF THE INVENTION Terms Used In the detailed description of the invention below, the following terms are used: The front or anterior surfaces of a bracket are those directed outwardly from a supporting tooth. Conversely, the rear or posterior surfaces are those which face toward the tooth. Dimensions along the bracket parallel to the incisal or occlusal line are referred to as its width and as being transverse and dimensions extending peφendicularly to the incisal/occlusal line are referred to as the height. The upright surfaces across the width of the bracket are its side surfaces and the surfaces along the top and bottom of the bracket are its incisal, occlusal or the gingival surfaces. Overview of the Bracket The bracket 5 of this invention is generally illustrated in FIG. 1 and its constituent parts are illustrated in detail with reference to FIGS. 1-12. The bracket 5 includes a supporting body or base 10 with a posterior surface 11 for attachment to a pad (not shown in these figures). The pad, in rum, is used to bond the bracket 5 to a tooth. As an example, the bracket body 10 can be approximately 0.120 inches wide and 0.140 inches high. Alternatively, the bracket 5 can be 0.100 inches wide with the same height. This narrower bracket 5 allows for a more exposed wire between the brackets 5, a feature that, in turn, allows for more flex in the wire. The bracket 5 is shown as a "Siamese" bracket, having two adjacent pairs of tying lugs or projections 12 each protruding about 0.037 inches beyond the base 10. A bracket 5 without lugs could, however, also incoφorate the features of this invention. The bracket 5 also includes outer side surfaces 15 and an anterior surface 17. The anterior surface 17 is interrupted by a generally rectangular, transverse archwire slot 18. The archwire slot 18, which is about 0.028 inches deep, spans the full width of the bracket 5 and is sized to snugly receive an archwire (not shown). Typically, the slot 18 will be about 0.018 to 0.022 inches high. In addition, the anterior corners of the slot 18 are formed with rounded or chamfered edges 19. These chamfered edges 19 assist in receiving and guiding the archwire into the slot 18. While the illustrated slot 18 is rectangular and is designed to receive a complementary rectangular archwire, it is to be understood that the slot 18 can be configured to receive archwires with round or other cross-sectional shapes. The archwire slot 18 can be covered with a slidable slide 21 which includes a roof portion 24 that spans across and beyond the entire slot 18. The roof portion's 24 dimension taken peφendicular to the longitudinal axis of the slot width is about 0.058 inches and thus greater than the corresponding dimension of the archwire slot 18. The slide 21 also includes a pair of runners 22 each engaging the posterior surfaces of a ledge 23 extending along each side 15 of the bracket 5. The ledges 23 preferably extend along the full height of the bracket 5, as can be seen from FIGS. 3 and 4. As can be seen, the runners 22 and the ledges 23 are parallel to the anterior surface 17 of the bracket 5. Thus, the supported roof portion 24 slides with its inner surface parallel to and flush against the anterior surface 17 of the bracket 5. This means the roof portion 24 remains adjacent to the anterior surface 17 of the bracket 5 regardless of whether the slide 21 is in its open or closed positions shown respectively in FIGS. 3 and 4. As can be seen from a comparison of these two figures, the open position is with the roof portion 24 clear of the archwire slot 18 and the closed position is with the roof poπion 24 overlapping the full width and height of the slot 18. When the slide 21 is in the closed position, the roof portion 24 together with the slot 18 define a fully enclosed "tube" for retaining an archwire across the bracket 5. As shown, for example, in Figures 11 and 12, the posterior surface 11 of the body 10 of the bracket 5 is generally concave. This concave shape is further defined by a compound curvature comprising, say, a first radius of curvature R, of about 0.750 inches and a second radius of curvature R 2 of about 0.178 inches. R t is the scalar value of the vector R', and R 2 is the scalar value of the vector R' 2 . R', translates circumferentially in a plane that is substantially parallel to the longitudinal axis 88 (see Figure 15) of a patient's tooth and R' 2 translates cicumferentially in a plane that is substantially peφendicular to the plane swept out by R',. It is to be understood that the values of R t and R 2 are very specific to both the tooth curvature and the specific tooth aligning prescription being followed by the orthodontist. Accordingly, the dimensions for R, and R 2 given above must be seen only as exemplary and are provided here primarily as a cross reference to the radii of curvature given in the later description of the tooth bonding pad. The Slide The slide 21 is described in greater detail with reference to FIGS. 5 to 8. From these figures it can be seen that each runner 22 is structurally connected to the roof portion 24 by an associated rigid leg 30. Each leg 30 is offset from the center line of the slide 21 so that there is adequate clearance across the full height of the archwire slot 18 when the slide 21 is in its closed position. Thus, transverse sliding movement of the runners 22 and legs 30 does not block or restrict access to any portion of the open transverse archwire slot 18. As shown in FIGS. 5 to 8, the posterior surface of the roof portion 24 includes two stamped-in detents 32, the function which will be described in detail below with reference to FIGS. 10 to 12. Each detent 32 is about 0.10 inches deep with one sloping long side 33 parallel to a generally vertical long side 34. Each detent 32 also has a generally flat roof portion parallel to the top of the roof portion 24. Typically, each detent 32 is about 0.072 inches long and 0.020 inches wide where it opens out. As the detents 32 are stamped into the roof portion 24, two associated ridges 32' are defined on the anterior surface of the roof portion 24. As is particularly apparent from FIG. 7, the rigid legs 30 and the runners 22 of the slide 21 are arranged in a unique manner. Prior to installing the slide 21 on the bracket 5, the legs 30 are sloped downwardly inward at an angle β to the vertical. The angle β may vary from slide 21 to slide 21 and depends on the distance δ between the inner engaging surfaces 25 of the runners 22. Typically the angle β is about 7°. When the slide 21 is fitted onto the bracket body 10, however, the legs 30 are forced slightly outward at their free ends so that the angle β tends to zero. This is illustrated in FIG. 12. This arrangement ensures that the runners 22 are biased inwardly into engagement with the outer sides 15 of the bracket 5. Moreover, the runners 22 define an included acute angle φ to their respective supporting legs 30. This angle φ is typically in the range of 75° to 89° and preferably about 83° to 85°. This configuration is particularly advantageous because, when the slide 21 is in place on the bracket body 10, the legs 30 are practically parallel with the sides 15 of the bracket 5, and only the inner engaging surfaces 25 of the runners 22 engage the ledge 23. This edge contact is instead of the entire runner surface being engaged as in the prior art. Thus the amount of metal-to-metal contact is reduced and the slide 21 slides relatively easily between the open and closed positions. In addition, as is particularly illustrated in FIG. 12, each ledge 23 slopes inwardly upward to define an included acute angle θ with the side 15 of the bracket 5. This configuration allows the slide 21 to better orient in the sliding direction to minimize twisting or rotating of the runner 22 with respect to the bracket 5. The angle θ is typically greater than the acute angle φ by about 1 to 4 degrees. This ensures that the advantageous edge contact between the runners 22 and the ledge 23/side 15 is maintained. As shown in FIGS. 5 to 8, the edges of the engaging surface 25 can be formed as chamfered edges 25'. This prevents a shaφ edge of the engaging surface 25 from engaging the bracket body 10, and reduces unwanted sticking which may result from shaφ edge contact. The chamfered edges 25' also reduce the amount of particles that would be formed from the shaφ edge contact that would otherwise occur. In addition, leading ends 22' of runners 22 may be chamfered thus forming a chamfered leading end 22". The chamfered leading ends 22" make it easier for the orthodontist to attach the slide 21 to the bracket body 10. More particularly, runners 22 with chamfered leading ends 22" permit the runners 22 to engage to the ledges 23 more readily than without the chamfers. Similar to the chamfered edges 25', the chamfered leading ends 22" also reduce unwanted sticking and particle lodging between the runners 22 and the ledges 23. Though preferred, it is understood that these chamfered engaging surface edges 25' and chamfered leading end 22" are not required to practice the invention. Another embodiment of the invention (see FIGS. 5 and 6), utilizes a semi¬ circular recess 26 to facilitate removal of particles that can lodge between the runner 22 and the ledge 23. Use of runners 22 having the recess 26 is also optional. The slide 21 is fabricated independently from the bracket 5 and is attached to the bracket 5 prior to installation of the bracket 5 on a tooth. While the slide 21 is normally retained on the bracket 5 during its use, it can be forced free from the bracket 5 for replacement puφoses or when use of the slide 21 is not required. The design of the bracket 5 and slide 21 is such that removal of the slide 21 can only be achieved by substantial prying movement, such as might be applied through use of a sealer or by cutting one of the legs 30. It is obviously desirable that the slide 21 not accidentally slide off the supporting bracket body 10 while within the mouth of a patient. To prevent this, positive stops (not shown) could be provided on the runners 22 or ledges 23 to limit the extent of sliding movement of slide 21. However, in the embodiment illustrated, outward movement of slide 21 is limited by the interaction of a spring 28 and the two detents 33 formed in the posterior surface of the roof poπion 24. This is illustrated with paπicular reference to FIGS. 9 to 12. The main body 10 of the bracket 5 includes a rectangular cavity 31 about 0.1 inches wide, 0.011 inches high and 0.035 inches deep. This cavity 31 receives and retains the spring 28. The spring 28 is a resilient spring formed from a length of wire and can have various cross-sectional shapes, such as circular, oval, square and rectangular. The spring 28 includes a bent section 35 that normally extends beyond the anterior surface 17 across the bracket 5. This allows the slide 21 to be releasably maintained in an open or a closed position by engagement of the spring 28 within detent 32. The spring 28 can be constructed of any suitable metallic or non-metallic material capable of deformation between a normal extended condition and a compressed condition as the slide 21 moves over it. As previously described, each detent 32 includes an inclined surface 33 and a generally flat poπion parallel to the anterior surface 17 as well as a wall 34. This wall 34 serves as a stop when engaged by the spring 28 and the position of the wall 34 defines the closed and open positions of slide 21, as respectively illustrated in FIGS. 10 and 11. The inclined surface 33 of the detent 32 assists in providing tactile "feel" to the slide movement, thereby guiding the user to the locked open or locked closed position of the slide 21 , i.e., where the spring 28 engages one of the walls 34. The forces exeπed on slide 21 by the engaged bent end section 35 also maintain the slide 21 in one or the other of its alternate positions. The above described design of the slide 21 has a number of advantages. The sliding suppoπ provided to the slide 21 in a direction parallel to the anterior surface 17 of the bracket 5 assures that forces applied to the bracket 5 by the archwire will not result in accidental release of the slide 21 from the bracket 5 when installed in the mouth of a patient. Any outwardly directed forces exeπed by the archwire on the slide 21 will be resisted by the stiff structure of slide 21, runners 22 and legs 30. These elements, therefore, should be constructed to withstand any foreseeable outward archwire forces without substantial deformation. In addition, the spring 28 and the complementary detents 32 must be designed to hold slide 21 in a locked position after installation in the mouth. The preferred transverse orientation of the spring 28 permits it to provide substantial resistance to cover movement during normal usage of the bracket 5 within the mouth of a patient. However, as a result of the inclined surfaces 33, the slide 21 still remains readily releasable to specifically directed forces applied by professionals during installation and adjustment of the bracket 5 and archwire. It is also impoπant to note that the resilient spring 28 only holds the slide 21 in an open or closed position. It is not utilized to hold the archwire in place within the archwire slot 18, nor does it hold the slide 21 against the bracket 5 itself. Bracket and pad combination As shown in FIGS. 13 and 14, the bracket 5 and slide 21 combination are mounted on a tooth bonding pad 50. As can be seen from FIG. 13, the bonding pad 50 is formed to approximate a parallelogram. In fact, three of the pad's 50 edges correspond to two shoπ edges, respectively, the mesial and distal edges 52 of the pad 50, and one long edge (or "occlusal" edge 54) of a parallelogram. The remaining edge, the illustrated gingival edge, is defined by two sloping sides 56 of a relatively flat triangle. The apex 57 of the triangle is slightly rounded. When attached to a tooth, the apex 57 is configured so that it always "points" towards the gingiva. The reason for this is described below. The bracket 5 is mounted onto the pad 50, as shown, with its horizontal centerline coinciding with the pad's 50 horizontal centerline 60, i.e., the centerline parallel to the occlusal edge 54. Figure 14 shows a perspective view of the bracket 5 mounted on the pad 50, the arrangement shown as would be for attaching to an upper tooth of a patient. Because, as described above, the apex 57 always points towards the gingiva when the pad 50 is attached to a tooth, the cavity 31 in the bracket 5 will be nearer the pad occlusal edge 54 than will be the slot 18 when the pad 50/bracket 5 combination is attached to the tooth. By contrast, for a lower tooth attachment (configuration not shown in the figures), the bracket 5 is mounted on the pad 50 such that the cavity 31 is closer to the gingiva than is the slot 18. Arranging the bracket to the pad differently, depending on whether an upper or lower tooth is being treated, allows the slot to be positioned where the slide is more easily operated by the treating orthodontist. In some arrangements, the bracket 5 is not fully "squared" on the pad 50. Instead it can be arranged so that its outer surfaces 15 define an angle 90°-γ to the pad's 50 central veπical axis which is parallel to its mesial and distal edges 52. Thus, although the geometric centers and the horizontal center lines of both bracket 5 and pad 50 coincide, they are rotated in plane by the angle 90°-γ with respect to each other. The angle γ may vary. The pad 50 is relatively small, typically having a height 62 of about 0.140 inches and a width 64 of about 0.168 inches. It is generally domed shaped with a uniform thickness. The lower, tooth engaging surface is concave with a compound curvature defined by two radii of curvature R P! and R κ . R P | and R n are the scalar values of the vectors R' P1 and respectively. R' P] translates circumferentially in a plane that is substantially parallel to the mesial and distal edges 52 of the pad 50 and R'^ translates circumferentially in a plane that is substantially parallel to the pad occlusal edge 54 of the pad 50. The scalar values R PI and Rp 2 are related to the scalar values Ri and R 2 defining the compound curvature of the posterior surface 11 of the body 10 of the bracket 5 (see FIGS. 11 and 12). The values of R P1 and R^ are each less than the respective values of R, and R 2 by an amount approximately equal to the thickness of the pad 50 (which is typically 0.0120 inches). Therefore, in this non-limiting example, R P1 is about 0.738 inches and R^ is about 0.166 inches. Accordingly, the bracket 5 is able to mate snugly with the upper surface of the pad 50 when the two are secured to each other. The values of R P1 and R n , like the values of R t and R 2 , are prescription and tooth dependent and can vary considerably from the dimensions given. Similarly, the dimensions of the pad can vary and the mesial and distal edges could be longer than the pad occlusal edge 54. The angles between the pad occlusal edge 54 and mesial and distal edges 52, could also be close to, or exactly, 90°. The values provided in the preceding paragraph are, therefore, only exemplary. Alignment of bracket and pad on the tooth As indicated previously, the concave shape of the tooth engaging the surface of the pad 50 provides better tooth bonding at the tooth and pad interface. Bonding can be further enhanced by providing the pad 50 with a roughened or mesh-covered bonding surface. In addition, the shape of the pad 50 assists the orthodontic practitioner in aligning the bracket 5 on a tooth. This feature is illustrated with reference to FIG. 15. The goal of orthodontic treatment is to move each tooth in the mouth to a paπicular predetermined, idealized position in the arch and to define a predetermined, idealized angle between its long axis and the mouth's occlusal plane. In reality, the tooth is not in its idealized position and its crown axis is not at its idealized angle to the occlusal plane. Hence the need for orthodontic treatment. In the mouth, the tooth long axis can best be approximated by visualizing the long axis of the crown, the only visual component of the tooth. It is also convenient to define the occlusal edge of an individual tooth and to bear in mind that, in untreated teeth, this edge will typically not coincide with the mouth's occlusal plane. These concepts are illustrated in FIG. 15. In this figure a tooth 80 includes a crown 82 and a root 84 having an apex 86. With respect to this structure, the tooth 80 is said to have a tooth long axis 88 which extends from the apex 86 to the tip 90 of the crown 82. The long axis 88 of the tooth 80 is shown disposed at an acute angle ω with respect to the occlusal edge 92 of the tooth 80. The figure also shows an occlusal plane 93. As can be seen, the tooth's occlusal edge 92 is both angled to and veπically displaced from the occlusal plane 93. These discrepancies are amplified for clarity and illustrate the need for oπhodontic treatment. The bracket 5 and pad 50 combination of the invention are schematically shown bonded to the tooth 80 with the pad's 50 axis 70 aligned along the long axis 88 of the tooth 80 and the pad occlusal edge 54 parallel to the tooth's 80 occlusal edge 92. The paπicular configuration of the pad 50 facilitates this arrangement. The pad's 50 mesial and distal edges 52 define two parallel lines straddling the tooth long axis 88. Positioning these two edges parallel to the long axis 88 can therefore be accomplished visually. In addition, the apex 57 of the pad 50 can be placed on a ridge of the tooth crown. This ridge closely approximates the tooth long axis 88. When the apex 57 is aligned with the crown ridge of the tooth, the pad 50 and the bracket 5 are properly aligned with the tooth long axis. Alignment is further facilitated by visual inspection of the pad occlusal edge 54, which should be aligned parallel to the occlusal edge 92 of the tooth 80. In practice, alignment with any one of these references provides a check of the alignment with any other reference. Thus one of the advantages of this invention is associated with the ease and speed of alignment of the pad 50 and bracket 5 with respect to the tooth 80. Optionally, the pad 50 may also contain a score mark 72 on the axis 70 of the pad 50 (see FIG. 15). The pad 50 and the bracket 5 are correctly aligned with the tooth long axis 88 when both the score mark 72 and apex 57 are aligned with the crown ridge of the tooth 80. The score mark 72 can therefore be used to further facilitate alignment. In practice, the orthodontic practitioner selects a bracket 5 in which the angle y or its complement corresponds to a specific prescription for the specific tooth. As the tooth 80 will not be in its idealized position, placing and aligning this selected bracket 5 on the tooth 80, as described above, will result in the archwire slot 18 being angled with respect to the mouth's occlusal plane 93. Thus a straight (unbent) archwire placed in the slot 18 and in similar slots in other brackets 5 will bear against the side walls of the slot 18 to cause it to tend to move. These forces are transmitted to the tooth 80 via the pad 50 and cause the tooth 80 to move towards its idealized position. The paπicular configuration of the bracket 5 described above also makes aligning of brackets 5 on adjacent teeth easier. The orthodontic practitioner may choose to align the pad occlusal edge 54 of adjacent brackets 5 with each other. More usually though, the practitioner will visually align the archwire slots 18 of adjacent brackets 5. In the unusual event that the slide 21 is in its closed position prior to placing the bracket 5 on the tooth 80, the archwire slot 18 will be hidden from view. Under normal circumstances this will make alignment of the archwire slots 18 difficult. This difficulty does not, however, arise with the bracket 5 and slide 21 combinations of the invention. As described above, the formation of the detents 32 in the roof poπion 24 of the slide 21 leaves bumps or ridges 32' protruding beyond the anterior surface of the roof poπion 24. The upper one of the ridges 32' is parallel with, and generally centered over, the longitudinal axis of the slot 18 when the slide 21 is closed. Thus, this ridge 32' could be used to assist in the alignment of the bracket 5. Conclusion It is to be understood that the invention is not limited to the specific features shown and described, since the means disclosed constitute preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims. For example, the bracket shown includes lugs for tying wires and other attachment devices. However, the basic features of the invention can be applied to bracket structures having no lugs. The configurations of these extensions, when present, can take any desired conventional or unconventional form. The extensions at the top and bottom of the bracket can be located in different planes. The extensions at the top of the bracket can be located in a plane different from that of the extensions at the bottom of the bracket. The extensions might also have the same or a different configuration at the top of the bracket than at the bottom of the bracket. Similarly, the illustrated bracket and slide combination can be bonded directly to a pad, as shown, or can be mounted on a tooth band for attachment to a tooth. Also, the present bracket can be made from any suitable material, including metals, plastics and ceramics, as well as a combination of such materials. The bracket and slide have generally been designed to be fabricated of metal, but the choice of materials is not critical to understanding or using this invention. The only limitation with regard to materials is the ability to efficiently fabricate or mold the bracket and slide as a cooperative mechanism to engage an archwire during orthodontic procedures. All publications and patent applications mentioned in this specification are herein incoφorated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incoφorated by reference. The invention now being fully described, it will be apparent to one of ordinary skill in the an that many changes and modifications can be made thereto without depaπing from the spirit or scope of the appended claims.

Claims: WHAT IS CLAIMED IS: 1. An orthodontic bracket assembly, comprising: (a) a bracket base (10), including a base anterior surface, a base posterior surface (11) and opposing sides (15) having ledges (23) formed therein; (b) a bracket (5), projecting from the base anterior surface and including a bracket anterior surface (17) interrupted by a slot (18); (c) a slide (21), including a roof poπion (24) and a leg (30) at each of two opposing ends of the roof poπion (24), each leg (30) having a runner (22) configured to engage a corresponding ledge (23); and (d) a bonding pad (50) suppoπing the base (10), including parallel first and second edges (52), and a third edge, nonpeφendicular to and between the first and second edges (52), the first and second edges (52) arranged to be parallel to a longitudinal axis of a tooth (80) when the bonding pad (50) is attached to the tooth (80). 2. The bracket assembly of claim 1, wherein the third edge fuπher includes two sides (56) that converge at a point (57). 3. The bracket assembly of claim 1, wherein the runners (22) permit the slide (21) to slide, between a first position in which the roof poπion (24) spans the slot (18) and a second position in which the roof poπion (24) is clear of the slot (18), when the runners (22) engage the ledges (23). 4. The bracket assembly of claim 3, wherein a cavity (31) within the bracket anterior surface (17) supporis a resilient spring (28), the spring (28) having a projecting poπion extending from the bracket anterior surface (17), and wherein the roof poπion (24) further includes a roof poπion posterior surface facing the bracket anterior surface (17) and a detent (32) for receiving the projecting poπion of the spring (28) when the slide (21) is slid into the first position. 5. The bracket assembly of claim 4, wherein the roof poπion posterior surface further includes a second detent (32) for receiving the projecting poπion of the spring (28) when the slide (21) is slid into the second position. 6. The bracket assembly of claim 2, wherein the pad (50) further includes a pad anterior surface having a score mark (72). 7. The bracket assembly of claim 1 , wherein each runner (22) includes an engaging surface (25) having a recess (26) therein. 8. The bracket assembly of claim 1, wherein each runner (22) includes an engaging surface (25) having chamfered edges (25'). 9. The bracket assembly of claim 8, wherein each runner (22) has a leading end (22') that is chamfered (22"). 10. The bracket assembly of claim 1, wherein an angle, formed between each leg (30) and the roof poπion (24) at the corresponding opposing end, increases upon engaging the runners (22) to the ledges (23). 11. An oπhodontic bracket assembly, comprising: (a) a bracket base (10), including a base anterior surface, a base posterior surface (11) and opposing sides (15) having ledges (23) formed therein; (b) a bracket (5), projecting from the base anterior surface and including a bracket anterior surface (17) interrupted by a slot (18); and (c) a slide (21), including a roof poπion (24) and a leg (30) at each of two opposing ends of the roof poπion (24), each leg (30) having a runner (22) configured to engage a corresponding ledge (23); wherein an angle, formed between each leg (30) and the roof poπion (24) at the corresponding opposing end, increases upon engaging the runners (22) to the ledges (23). 12. The bracket assembly of claim 11, wherein the runners (22) permit the slide (21) to slide, between a first position in which the roof poπion (24) spans the slot (18) and a second position in which the roof poπion (24) is clear of the slot (18), when the runners (22) engage the ledges (23). 13. The bracket assembly of claim 12, wherein a cavity (31) within the bracket anterior surface (17) suppoπs a resilient spring (28), the spring (28) having a projecting poπion extending from the bracket anterior surface (17), and wherein the roof poπion (24) further includes a roof poπion posterior surface facing the bracket anterior surface (17) and a detent (32) for receiving the projecting poπion of the spring (28) when the slide (21) is slid into the first position. 14. The bracket assembly of claim 13, wherein the roof poπion posterior surface fiinher includes a second detent (32) for receiving the projecting poπion of the spring (28) when the slide (21) is slid into the second position. 15. The bracket assembly of claim 11 , further comprising a bonding pad (50), the bonding pad (50) including: (a) a pad anterior surface onto which the base (10) is mounted; and (b) parallel first and second edges (52) arranged to be parallel to a longitudinal axis of a tooth (80) when the pad (50) is attached to the tooth (80). 16. The bracket assembly of claim 15, wherein the pad (50) fuπher includes a third edge, nonpeφendicular to and between the first and second edges (52). 17. The bracket assembly of claim 16, wherein the third edge includes two sides (56) that converge at a point (57). 18. The bracket assembly of claim 17, wherein the pad anterior surface has a score mark (72). 19. The bracket assembly of claim 11, wherein each runner (22) includes an engaging surface (25) having a recess (26) therein. 20. The bracket assembly of claim 11 , wherein each runner (22) includes an engaging surface (25) having chamfered edges (25'). 21. The bracket assembly of claim 20, wherein each runner (22) has a leading end (22') that is chamfered (22"). 22. An orthodontic bracket assembly, comprising: (a) a bracket base (10), including a base anterior surface, a base posterior surface (11) and opposing sides (15) having ledges (23) formed therein; (b) a bracket (5), projecting from the base anterior surface and including a bracket anterior surface (17) interrupted by a slot (18); and (c) a slide (21), including a roof poπion (24) and a leg (30) at each of two opposing ends of the roof poπion (24), each leg (30) having a runner (22) with an engaging surface (25), the engaging surfaces (25) having recesses (26) and configured to engage the ledges (23). 23. The bracket assembly of claim 22, wherein the runners (22) permit the slide (21) to slide, between a first position in which the roof poπion (24) spans the slot (18) and a second position in which the roof poπion (24) is clear of the slot (18), when the runners (22) engage the ledges (23). 24. The bracket assembly of claim 23, wherein a cavity (31) within the bracket anterior surface (17) suppoπs a resilient spring (28), the spring (28) having a projecting poπion extending from the bracket anterior surface (17), and wherein the roof poπion (24) fuπher includes a roof poπion posterior surface facing the bracket anterior surface (17) and a detent (32) for receiving the projecting poπion of the spring (28) when the slide (21) is slid into the first position. 25. The bracket assembly of claim 24, wherein the roof poπion posterior surface fuπher includes a second detent (32) for receiving the projecting poπion of the spring (28) when the slide (21) is slid into the second position. 26. The bracket assembly of claim 22, fuπher comprising a bonding pad (50), the bonding pad (50) including: (a) a pad anterior surface onto which the base (10) is mounted; and (b) parallel first and second edges (52) arranged to be parallel to a longimdinal axis of a tooth (80) when the pad (50) is attached to the tooth (80). 27. The bracket assembly of claim 26, wherein the pad (50) further includes a third edge, nonpeφendicular to and between the first and second edges (52). 28. The bracket assembly of claim 27, wherein the third edge includes two sides (56) that converge at a point (57). 29. The bracket assembly of claim 28, wherein the pad anterior surface has a score mark (72). 30. The bracket assembly of claim 22, wherein each runner (22) includes an engaging surface (25) having chamfered edges (25'). 31. The bracket assembly of claim 30, wherein each runner (22) has a leading end (22') that is chamfered (22"). 32. The bracket assembly of claim 22, wherein an angle, formed between each leg (30) and the roof poπion (24) at the corresponding opposing end, increases upon engaging the runners (22) to the ledges (23). 33. An orthodontic bracket assembly, comprising: (a) a bracket base (10), including a base anterior surface, a base posterior surface (11) and opposing sides (15) having ledges (23) formed therein; (b) a bracket (5), projecting from the base anterior surface and including a bracket anterior surface (17) interrupted by a slot (18); and (c) a slide (21), including a roof poπion (24) and a leg (30) at each of two opposing ends of the roof poπion (24), each leg (30) having a runner (22) with an engaging surface (25), with chamfered edges (25'), for engaging a corresponding ledge (23). 34. The bracket assembly of claim 33, wherein the runners (22) permit the slide (21) to slide, between a first position in which the roof poπion (24) spans the slot (18) and a second position in which the roof poπion (24) is clear of the slot (18), when the runners (22) engage the ledges (23). 35. The bracket assembly of claim 34, wherein a cavity (31) in the bracket anterior surface (17) suppoπs a resilient spring (28), the spring (28) having a projecting poπion extending from the bracket anterior surface (17), and wherein the roof poπion (24) fuπher includes a roof poπion posterior surface facing the bracket anterior surface (17) and a detent (32) for receiving the projecting poπion of the spring (28) when the slide (21) is slid into the first position. 36. The bracket assembly of claim 35, wherein the roof poπion posterior surface further includes a second detent (32) for receiving the projecting poπion of the spring (28) when the slide (21) is slid into the second position. 37. The bracket assembly of claim 33, further comprising a bonding pad (50), the bonding pad (50) including: (a) a pad anterior surface onto which the base (10) is mounted; and (b) parallel first and second edges (52) arranged to be parallel to a longitudinal axis of a tooth (80) when the pad (50) is attached to the tooth (80). 38. The bracket assembly of claim 37, wherein the pad (50) further includes a third edge, nonpeφendicular to and between the first and second edges (52). 39. The bracket assembly of claim 38, wherein the third edge includes two sides (56) that converge at a point (57). 40. The bracket assembly of claim 39, wherein the pad anterior surface has a score mark (72). 41. The bracket assembly of claim 33, wherein each engaging surface (25) has a recess (26). 42. The bracket assembly of claim 41, wherein each runner (22) has a leading end (22') that is chamfered (22"). 43. The bracket assembly of claim 33, wherein an angle, formed between each leg (30) and the roof poπion (24) at the corresponding opposing end, increases upon engaging the runners (22) to the ledges (23). AMENDED CLAIMS [received by the Internationa l Bureau on 26 September 1997 ( 26.09.97) ; original c l a ims 1 , 1 5 , 26 and 37 amended ; new c laims 44-46 added ; rema ining cla ims unchanged ( 7 pages ) ] 1. An oπhodontic bracket assembly, comprising: (a) a bracket base (10), including a base anterior surface, a base posterior surface (11) and opposing sides (15) having ledges (23) formed therein; (b) a bracket (5), projecting from the base anterior surface and including a bracket anterior surface (17) interrupted by a slot (18); (c) a slide (21), including a roof poπion (24) and a leg (30) at each of two opposing ends of the roof poπion (24), each leg (30) having a runner (22) configured to engage a corresponding ledge (23); and (d) a bonding pad (50) suppoπing the base (10), including parallel first and second edges (52) nonpeφendicular to the slot (18) and a third edge, nonpeφendicular to and between the first and second edges (52), the first and second edges (52) arranged to be parallel to a longitudinal axis (88) of a tooth (80) upon attachment of the assembly to the tooth (80). 2. The bracket assembly of claim 1. wherein the third edge fuπher includes two sides (56) that converge at a point (57). 3. The bracket assembly of claim 1 , wherein the runners (22) permit the slide (21) to slide, between a first position in which the roof poπion (24) spans the slot (18) and a second position in which the roof poπion (24) is clear of the slot (18), when the runners (22) engage the ledges (23). 4. The bracket assembly of claim 3, wherein a cavity (31) within the bracket anterior surface (17) suppoπs a resilient spring (28), the spring (28) having a projecting poπion extending from the bracket anterior surface (17), and wherein the roof poπion (24) fuπher includes a roof poπion posterior surface facing the bracket anterior surface (17) and a detent (32) for receiving the projecting poπion of the spring (28) when the slide (21) is slid into the first position. 5. The bracket assembly of claim 4, wherein the roof poπion posterior surface fuπher includes a second detent (32) for receiving the projecting poπion of the spring (28) when the slide (21) is slid into the second position. 6. The bracket assembly of claim 2, wherein the pad (50) further includes a pad anterior surface having a score mark (72). 7. The bracket assembly of claim 1 , wherein each runner (22) includes an engaging surface (25) having a recess (26) therein. 8. The bracket assembly of claim 1 , wherein each runner (22) includes an engaging surface (25) having chamfered edges (25'). 9. The bracket assembly of claim 8, wherein each runner (22) has a leading end (22') that is chamfered (22"). 10. The bracket assembly of claim 1 , wherein an angle, formed between each leg (30) and the roof portion (24) at the corresponding opposing end, increases upon engaging the runners (22) to the ledges (23). 11. An orthodontic bracket assembly, comprising: (a) a bracket base (10), including a base anterior surface, a base posterior surface (11) and opposing sides (15) having ledges (23) formed therein; (b) a bracket (5), projecting from the base anterior surface and including a bracket anterior surface (17) interrupted by a slot (18); and (c) a slide (21), including a roof portion (24) and a leg (30) at each of two opposing ends of the roof portion (24), each leg (30) having a runner (22) configured to engage a corresponding ledge (23); wherein an angle, formed between each leg (30) and the roof portion (24) at the corresponding opposing end, increases upon engaging the runners (22) to the ledges (23). 12. The bracket assembly of claim 11 , wherein the runners (22) permit the slide (21) to slide, between a first position in which the roof portion (24) spans the slot (18) and a second position in which the roof portion (24) is clear of the slot (18), when the runners (22) engage the ledges (23). 13. The bracket assembly of claim 12, wherein a cavity (31) within the bracket anterior surface (17) supports a resilient spring (28), the spring (28) having a projecting portion extending from the bracket anterior surface (17), and wherein the roof portion (24) further includes a roof portion posterior surface facing the bracket anterior surface (17) and a detent (32) for receiving the projecting portion of the spring (28) when the slide (21) is slid into the first position. 14. The bracket assembly of claim 13, wherein the roof portion posterior surface further includes a second detent (32) for receiving the projecting portion of the spring (28) when the slide (21) is slid into the second position. 15. The bracket assembly of claim 11 , further comprising a bonding pad (50), the bonding pad (50) including: (a) a pad anterior surface onto which the base (10) is mounted; and (b) parallel first and second edges (52) nonpeφendicular to the slot (18). 16. The bracket assembly of claim 15, wherein the pad (50) further includes a third edge, nonpeφendicular to and between the first and second edges (52). 17. The bracket assembly of claim 16, wherein the third edge includes two sides (56) that converge at a point (57). 18. The bracket assembly of claim 17, wherein the pad anterior surface has a score mark (72). 19. The bracket assembly of claim 11 , wherein each runner (22) includes an engaging surface (25) having a recess (26) therein. 20. The bracket assembly of claim 11 , wherein each runner (22) includes an engaging surface (25) having chamfered edges (25'). 21. The bracket assembly of claim 20, wherein each runner (22) has a leading end (22') that is chamfered (22"). 22. An orthodontic bracket assembly, comprising: (a) a bracket base (10), including a base anterior surface, a base posterior surface (11) and opposing sides (15) having ledges (23) formed therein; (b) a bracket (5), projecting from the base anterior surface and including a bracket anterior surface (17) interrupted by a slot (18); and (c) a slide (21), including a roof portion (24) and a leg (30) at each of two opposing ends of the roof portion (24), each leg (30) having a runner (22) with an engaging surface (25), the engaging surfaces (25) having recesses (26) and configured to engage the ledges (23). 23. The bracket assembly of claim 22, wherein the runners (22) permit the slide (21) to slide, between a first position in which the roof portion (24) spans the slot (18) and a second position in which the roof portion (24) is clear of the slot (18), when the runners (22) engage the ledges (23). 24. The bracket assembly of claim 23, wherein a cavity (31) within the bracket anterior surface (17) supports a resilient spring (28), the spring (28) having a projecting portion extending from the bracket anterior surface (17), and wherein the roof portion (24) further includes a roof portion posterior surface facing the bracket anterior surface (17) and a detent (32) for receiving the projecting portion of the spring (28) when the slide (21) is slid into the first position. 25. The bracket assembly of claim 24, wherein the roof portion posterior surface further includes a second detent (32) for receiving the projecting portion of the spring (28) when the slide (21) is slid into the second position. 26. The bracket assembly of claim 22, further comprising a bonding pad (50), the bonding pad (50) including: (a) a pad anterior surface onto which the base (10) is mounted; and (b) parallel first and second edges (52) nonpeφendicular to the slot (18). 27. The bracket assembly of claim 26, wherein the pad (50) further includes a third edge, nonpeφendicular to and between the first and second edges (52). 28. The bracket assembly of claim 27, wherein the third edge includes two sides (56) that converge at a point (57). 29. The bracket assembly of claim 28, wherein the pad anterior surface has a score mark (72). 30. The bracket assembly of claim 22, wherein each runner (22) includes an engaging surface (25) having chamfered edges (25'). 31. The bracket assembly of claim 30, wherein each runner (22) has a leading end (22') that is chamfered (22"). 32. The bracket assembly of claim 22, wherein an angle, formed between each leg (30) and the roof portion (24) at the corresponding opposing end, increases upon engaging the runners (22) to the ledges (23). 33. An orthodontic bracket assembly, comprising: (a) a bracket base (10), including a base anterior surface, a base posterior surface (11) and opposing sides (15) having ledges (23) formed therein; AMENDED SHEET (ARTICLE 19) ILL (b) a bracket (5), projecting from the base anterior surface and including a bracket anterior surface (17) interrupted by a slot (18); and (c) a slide (21), including a roof portion (24) and a leg (30) at each of two opposing ends of the roof portion (24), each leg (30) having a runner (22) with an engaging surface (25), with chamfered edges (25'), for engaging a corresponding ledge (23). 34. The bracket assembly of claim 33, wherein the runners (22) permit the slide (21) to slide, between a first position in which the roof portion (24) spans the slot (18) and a second position in which the roof portion (24) is clear of the slot (18), when the runners (22) engage the ledges (23). 35. The bracket assembly of claim 34, wherein a cavity (31) in the bracket anterior surface (17) supports a resilient spring (28), the spring (28) having a projecting portion extending from the bracket anterior surface (17), and wherein the roof portion (24) further includes a roof portion posterior surface facing the bracket anterior surface (17) and a detent (32) for receiving the projecting portion of the spring (28) when the slide (21) is slid into the first position. 36. The bracket assembly of claim 35, wherein the roof portion posterior surface further includes a second detent (32) for receiving the projecting portion of the spring (28) when the slide (21) is slid into the second position. 37. The bracket assembly of claim 33, further comprising a bonding pad (50), the bonding pad (50) including: (a) a pad anterior surface onto which the base (10) is mounted; and (b) parallel first and second edges (52) nonpeφendicular to the slot (18). 38. The bracket assembly of claim 37, wherein the pad (50) further includes a third edge, nonpeφendicular to and between the first and second edges (52). 39. The bracket assembly of claim 38, wherein the third edge includes two sides (56) that converge at a point (57). 40. The bracket assembly of claim 39, wherein the pad anterior surface has a score mark (72). 41. The bracket assembly of claim 33, wherein each engaging surface (25) has a recess (26). 42. The bracket assembly of claim 41 , wherein each runner (22) has a leading end (22') that is chamfered (22"). 43. The bracket assembly of claim 33, wherein an angle, formed between each leg (30) and the roof portion (24) at the corresponding opposing end, increases upon engaging the runners (22) to the ledges (23). 44. The bracket assembly of claim 15, wherein the first and second edges (52) are arranged to be parallel to a longitudinal axis (88) of a tooth (80) upon attachment of the assembly to the tooth (80). 45. The bracket assembly of claim 26, wherein the first and second edges (52) are arranged to be parallel to a longitudinal axis (88) of a tooth (80) upon attachment of the assembly to the tooth (80). 46. The bracket assembly of claim 37, wherein the first and second edges (52) are arranged to be parallel to a longitudinal axis (88) of a tooth (80) upon attachment of the assembly to the tooth (80). STATEMENT UNDER ARTICLE 19(1) The International Search Report identified U.S. Patents 5,466,151 ('151 patent), 4,712,999 ('999 patent) and 4,659,309 ('309 patent) as Category Y references to support the argument that the claimed invention lacks an inventive step. The ' 151 patent discloses a ligatureless orthodontic bracket including a closure having a cover that can be positioned in an open or closed position over an archwire slot. When in the open position, the slot is exposed. When in the closed position, the slot is concealed by the cover. The '151 bracket also includes a base that suppoπs the bracket and can be bonded to a tooth.

Inventors: NICHOLS WILLIAM, SAGHAFI SAEED, SWENSEN MYRON, NICHOLS, WILLIAM, SAGHAFI, SAEED, SWENSEN, MYRON
Applicants: COMPANY ORTHODONTICS A, NICHOLS WILLIAM, SAGHAFI SAEED, SWENSEN MYRON, "A" COMPANY ORTHODONTICS, NICHOLS, WILLIAM, SAGHAFI, SAEED, SWENSEN, MYRON
Application year: 1997
Main classification: A61C3
IPC codes: A61C7