Appliances and related methods use a resilient retention member that is retained in a recess within a body that is optionally made from a suitably translucent ceramic material. The retention member, optionally in combination with one or more side walls of the recess, provides two or more regions for accommodating a protrusion. The protrusion, in turn, is part of a sliding door which can be opened or closed depending on the equilibrium position of the protrusion with respect to the two or more regions. Based on the engagement between the protrusion and the retention member, these appliances can provide discrete opened and closed door positions to facilitate archwire ligation.

FIELD OF THE INVENTION

Provided are appliances and related methods used in orthodontic treatment. More particularly, the provided appliances and methods relate to orthodontic appliances that are self-ligating.

BACKGROUND

Orthodontics is a field of dentistry associated with the professional supervision, guidance and correction of malpositioned teeth. The benefits of orthodontic treatment include attaining and maintaining a proper bite function, enhancing facial aesthetics, and improving dental hygiene. To achieve these goals, the orthodontic professional often makes use of corrective appliances that engage to the patient's teeth and apply gentle therapeutic forces to move the teeth toward proper positions.

One common type of treatment uses tiny slotted appliances called orthodontic brackets, which are adhesively attached to either the front or back surfaces of the teeth. To begin treatment, a resilient arch-shape wire (“archwire”) is received into the slot of each bracket. The ends of the archwire are generally captured in appliances called molar tubes, which are affixed to the patient's molar teeth. As the archwire slowly returns to its original shape, it acts as a track that guides the movement of teeth toward desired positions. The brackets, tubes, and archwire are collectively known as “braces.”

The procedure used to engage and activate the archwire on the orthodontic bracket is known as ligation. Traditional brackets are ligated to the archwire with the help of one or more pairs of opposing tiewings, or cleat-like projections on the bracket body. The archwire is placed in the archwire slot and generally a tiny elastomeric “O”-ring ligature, or alternatively metal ligature wire, is tightened over the archwire and under the undercut portions of tiewings located on opposite sides of the archwire slot. The ligature thus secures the archwire within the archwire slot of each bracket and provides a precise mechanical coupling between these bodies.

Ligatures have numerous drawbacks. For example, elastomeric ligatures have a tendency to lose their elasticity over time, resulting in inconsistent archwire sliding mechanics. While these ligatures can be made translucent for aesthetic treatment, they also tend to easily stain. Ligation using a ligature wire, on the other hand, can be quite cumbersome and time-consuming. Being made of metal, ligature wire is also generally considered non-aesthetic.

Self-ligating brackets present a solution to the above problems. These appliances generally use a clip, spring member, door, shutter, bail, or other ligation mechanism built into the bracket itself to retain the archwire in the slot, thereby obviating use of a separate ligature. Several advantages can derive from the use of self-ligating brackets. For example, these appliances can decrease friction between the archwire and the bracket compared with brackets ligated with elastomeric ligatures, potentially providing faster leveling and aligning of teeth in early stages of treatment. Depending on the ligation mechanism, these appliances can also simplify the installation and removal of an archwire, significantly reducing chair time for the treating professional. Finally, self-ligating brackets can also provide better hygiene than conventional brackets, which use elastomeric ligatures and ligature wires that can trap food and plaque.

SUMMARY

The realization of an aesthetic self-ligating bracket poses a number of technical challenges and tradeoffs. For example, the material used in a clip, spring member, door, bail, or other ligation mechanism is typically metallic, and strongly contrasts with the natural color of teeth. While polymeric materials are aesthetic and can be configured for this function, polymers are generally soft, vulnerable to wear, and stain easily during the course of treatment. Finally, ceramic materials have long been known to provide reasonable strength, resistance to staining, and excellent aesthetics. However, these materials are also brittle, can be difficult to machine and assemble, and do not have the resiliency needed for most ligation mechanisms.

The provided appliances and related methods overcome this dilemma by using a ligation mechanism that can be embedded within an aesthetic appliance assembly. In an exemplary embodiment, these appliances use a retention member located in a recess of a ceramic body. The retention member, optionally in combination with one or more side walls of the recess, provides a plurality of regions for accommodating a protrusion. The protrusion, in turn, is part of a door slidably engaged to the body and can be opened or closed depending on the equilibrium position of the protrusion with respect to the two or more regions. Based on the engagement between the protrusion and the clip, these appliances can provide discrete, pre-defined opened and closed door positions, thereby facilitating archwire ligation for the treating professional.

In one aspect, an orthodontic appliance is provided. The appliance comprises: a base; a body extending outwardly from the base; an archwire slot extending across the body in a generally mesial-distal direction; a recess located on the body adjacent the archwire slot; a retention member received in the recess, the retention member dividing the recess into at least first and second regions; and a door slidably engaged to the body and having a protrusion, the protrusion extending into the first region when the door is open to allow access to the archwire slot and extending into the second region when the door is closed to prevent access to the archwire slot.

In another aspect, an orthodontic appliance comprising: a base; a body extending outwardly from the base; an archwire slot extending across the body in a generally mesial-distal direction; a recess located on the body adjacent the archwire slot, the recess having a bottom wall and opposing first and second side walls; a retention member received in the recess; and a door slidably engaged with the body and having a protrusion extending into the recess, the retention member resiliently deflecting to toggle the protrusion between a first position wherein the door is open to allow access to the archwire slot and a second position wherein the door is closed to prevent access to the archwire slot.

In yet another aspect, an orthodontic appliance is provided, comprising: a base; a body extending outwardly from the base; an archwire slot extending across the body in a generally mesial-distal direction; a recess located on the body adjacent the archwire slot, the recess having a bottom wall and opposing first and second side walls; a retention member received in the recess, the retention member comprising: a center section extending along the bottom wall and having first and second ends; an arched section joined to the first end and having an apex; and a tail section joined to the second end and extending at an acute angle relative to the center section; and a door slidably engaged with the body and having a protrusion extending into the recess, wherein the protrusion resides between the first side wall and the arched section when the door is open to allow access to the archwire slot and the protrusion rests between the arched section and the second side wall when the door is closed to prevent access to the archwire slot.

In yet another aspect, a method is provided for assembling an orthodontic appliance having ceramic body, a ceramic door having a protrusion, and a retention member. The method comprises: placing the retention member into a recess located in the body; slidably engaging the door along a pair of rails disposed on the body until the protrusion contacts an exterior surface of the retention member; and urging the door against the retention member until the protrusion is received within a region of the recess that is at least partially defined by the combination of the recess and an interior surface of the retention member.

DEFINITIONS

As used herein:

“Mesial” means in a direction toward the center of the patient's curved dental arch.

“Distal” means in a direction away from the center of the patient's curved dental arch.

“Occlusal” means in a direction toward the outer tips of the patient's teeth.

“Gingival” means in a direction toward the patient's gums or gingiva.

“Facial” means in a direction toward the patient's lips or cheeks.

“Lingual” means in a direction toward the patient's tongue.

DETAILED DESCRIPTION

The following sections further describe particular embodiments of the invention directed to orthodontic appliances, kits, and methods of assembling the same. The illustrated embodiments in this disclosure are exemplary only and should not be construed to unduly limit the invention. For example, one of ordinary skill can adapt the disclosed appliances, kits, and methods for attachment to either the facial or lingual surfaces of teeth, to different teeth within the same dental arch, and to teeth of either the upper or lower dental arches. The appliances, kits, and methods described herein may also either be customized or non-customized to the individual patient undergoing treatment. Preferred embodiments include appliance components that are made from a translucent ceramic for improved aesthetics. Notwithstanding, material and dimensional specifications and intended methods of use could vary, even significantly, from those disclosed herein without departing from the scope of the claimed invention.

An orthodontic appliance according to one embodiment, designated by the numeral100, is shown inFIGS. 1 and 2in assembled form. The appliance100has a base102and a body104extending outwardly from the base102. The bottom of the base102has a bonding surface106having a concave three-dimensional surface contour generally matching that of a respective tooth to which the appliance100is to be bonded. The bonding surface106can optionally have holes, grooves, recesses, undercuts, partially embedded particles, mesh, a chemical bond enhancement material, a micro-etched surface, or any other material, structure, or combination thereof, to facilitate adhesive bonding of the appliance100to a tooth surface.

An archwire slot108, having a generally rectilinear configuration, extends in a generally mesial-distal direction across a generally facial-facing surface of the body104. Controlling access to the archwire slot108is a door110, which is slidably received in the body104and shown in its closed position inFIGS. 1-2. In this particular embodiment, the door110has a pair of rails111, each extending along a generally occlusal-gingival direction on the mesial and distal sides of the door110. The rails111slide along a pair of opposing complementary grooves113disposed in the body104. There may be appropriate tolerances between the rails111and the grooves113to facilitate sliding of the door110and avoid binding. A portion of the door110extends across a central portion of the archwire slot108, thereby preventing ingress or egress of an archwire (not shown here) with respect to the slot108of the appliance100. Optionally and as shown, the leading edge112of the door110abuts against the gingival side wall114of the archwire slot108when the door110is closed.

Again referring toFIGS. 1-2, the door110is capable of sliding both occlusal and gingival directions to toggle between an open position allowing access to the archwire slot108and a closed position preventing access to the archwire slot108. Under most circumstances, the door110is adequate on its own to ligate an archwire to the appliance100. If desired, however, a treating professional can elect to manually ligate the archwire with the assistance of the undercuts116and tiewings118located on the body104. Ligation can be achieved, for example, by securing an elastomeric o-ring or ligature wire beneath the undercuts116, over an archwire received in the slot108, and beneath the tiewings118. The undercuts116and tiewings118may also be used to secure a power chain to two or more teeth if so desired.

In exemplary embodiments, some or all of the base102, body104, and door110are made from a translucent ceramic material. Particularly preferred ceramic materials include the fine-grain polycrystalline alumina materials described in issued U.S. Pat. No. 6,648,638 (Castro, et al.). These ceramic materials are known for their high strength and also provide superior aesthetics compared with metallic materials because they transmit light and can visually blend in with the color of the underlying tooth surface.

FIGS. 1-2also show a vertical groove119that extends from the gingival side to the occlusal sides of the facial side of the body104. The groove119runs between the tiewings118, bifurcating the body104into mesial and distal halves. In some embodiments, the vertical groove119at least partially defines a frangible web located between the bottom of the groove119and the bonding surface106and enables the appliance to be conveniently squeeze-debonded by fracturing a frangible web and pivoting the mesial and distal halves of the appliance100toward each other. Further options and advantages are described in issued U.S. Pat. No. 5,366,372 (Hansen, et al.).

Various mechanisms can be implemented to toggle the door110between discrete positions—for example, between open and closed positions. Mechanisms that provide local equilibrium positions for the door110can advantageously prevent the door from spontaneously closing when a treating professional is placing an archwire in the slot108or conversely, spontaneously opening during the course of treatment.

FIGS. 3, 4A and 4Bshows the clip120received in a recess122embedded in an overall appliance assembly that includes the door110(for clarity, not shown inFIG. 3), body104, and base102. The recess122is located adjacent the archwire slot108and has a generally rectangular shape in plan view, with opposing mesial and distal side walls124, opposing occlusal and gingival side walls126and a bottom wall128. Although some clearance is provided along all four side walls124,126, the inner walls of the recess122generally conform to the exterior surfaces of the clip120and prevent the clip120from substantially moving in lateral directions parallel to the bottom wall128. It is to be understood that the clip120is merely an exemplary retention member, and an alternative retention member having a different geometry or orientation may be substituted for the clip120without compromising its function.

The clip120has an overall trough-like shape, with a bottom section130, and a pair of side sections132. Preferably the clip120is made from a resilient material having a high elastic strain limit, such as a shape memory material based on an alloy of nickel and titanium, although other materials such as stainless steel, beta titanium, cobalt alloys (e.g. from Elgiloy Specialty Metals, Elgin, Ill.), or even certain plastic materials may be used. The interior surfaces of the side sections132include a pair of opposing inward-facing projections134. As particularly shown inFIG. 4B, the pair of projections134, which in this case are centrally located on the clip120, divides the recess122into occlusal and gingival regions138,140that communicate with each other through the narrowed area between the projections134.

As further shown inFIG. 4C, a protrusion136of the door110is located in the gingival region140. The protrusion136can be either an integral or discrete part of the door110(remaining parts of the door110hidden inFIGS. 3 and 4C) and located such that the position of the protrusion136in the recess122corresponds to a closed position of the door110as shown inFIGS. 1-2. The side walls124,126hold the protrusion136captive within the regions138,140and prevent the door110from becoming dislodged from the body104. Unless the door110is being actively opened or closed, the protrusion136generally assumes one of the two positions defined by the regions138,140, corresponding to the closed and open positions of the door110, respectively.

The door110can be assembled to the body104in any of a number of different ways. These figures show, for example, the protrusion136as a separate component. In this figure, the protrusion136is received and retained in an aperture137extending through the door110in a generally facial-lingual direction, allowing the door110to be first slidably engaged with the body104, and then the protrusion136received through the aperture from the facial side of the door110to engage the clip120. For aesthetic reasons, the aperture137on the facial side of the door110can then be sealed with a suitable aesthetic plug139to hide the protrusion136. In an alternative method of assembly, the clip120and protrusion136can be inserted together into the door110and recess122from the lingual direction by means of an enlarged opening in the base102(not shown here). The opening can be subsequently patched using a suitably configured plug. In any of the above embodiments, the protrusion136can be joined to the main part of the door110using any known methods, including being press fit, brazed or adhesively into the door110.

In yet another embodiment, the protrusion136is an integral component of the door110. In this case, the door110can be slidably engaged to the body104by sliding the door110/protrusion136through a temporary opening made in, for example, one of the occlusal-gingival side walls126of the recess122. After the protrusion136is received in one of the regions138,140, the opening can then be suitably plugged or otherwise sealed as described above to capture the clip120and protrusion136in the recess122.

The protrusion136need not be a rigid member. In some embodiments, the protrusion is itself somewhat complaint. For example, the protrusion136could be a spring-like member such as a hollow tube made from a shape memory alloy and capable of resiliently bending, stretching or compressing as it slides relative to the clip120. Advantageously, the combination of a resilient clip120and resilient protrusion136can provide greater design freedom to optimize force characteristics of the door110. As yet another embodiment, the protrusion136is resilient while the clip120is substantially rigid.

FIGS. 6-8show an appliance200according to another embodiment. Like the appliance100previously described, the appliance200has a base202, a body204, an archwire slot208extending in a mesial-distal direction across the body204, and a generally cross-shaped recess222adjacent the slot208. Further, a door210is slidably engaged to the body204, where the door210includes a pair of protrusions236a,236bthat extend into the recess222when the door210is in its closed position. Instead of using a clip with a trough-like configuration, however, the appliance200uses an exemplary resilient, planar clip220having a generally “H”-shaped configuration as illustrated inFIG. 6. As shown, the clip220resides in a reference plane generally perpendicular to an occlusal-gingival axis and generally parallel to the occlusal and gingival walls of the archwire slot208. The recess222has a pair of lateral cutouts223that hold the clip220captive within the recess222.

Additional features on the underside of the door210are shown in the disassembled view of the appliance200inFIG. 7. As shown here, the first and second protrusions236a,236bboth extend outwardly from the main part of the door210toward a generally lingual direction, and are spaced apart from each other along the direction of travel of the door210.

FIG. 8shows, in cross-section, the interaction between the door210and the clip220when the appliance200is assembled. In more detail, the clip220has a center section250and mesial and distal sections252,254joined to respective mesial and distal ends of the center section250and extending toward a generally facial direction. The ends of the sections252,254include opposing, inward-facing projections234. Mesial and distal leg sections256are also joined to the mesial and distal terminal ends of the center section250and extend toward, and contact, the bottom wall of the recess222to provide a stable orientation of the clip220in the recess222.

From the disassembled state, the door210can be slidably received in the body204, resulting in the first protrusion236acontacting the narrowed area within the recess222presented by the inward-facing projections234, as shown inFIG. 6. At this point, the first protrusion236aresides in a first region238of the recess222. When sufficient force is applied to the door210(here, in a generally gingival direction) then the sections252,254spread apart allowing the first protrusion236ato pass through and enter a second region240of the recess222while the second protrusion236bis now in the first region238. In this configuration, the door210is in its open position.

If force is maintained against the door210toward the same direction, then the second protrusion236burges against the projections234until sufficient force results in the sections252,254again spreading apart and allowing the second protrusion236bto join the first protrusion236ain the second region240. In this relative arrangement, the door210is now in its closed position. The protrusions236a,236btherefore reside in the first and second regions238,240(on opposite sides of the clip220) when the door is open, while the protrusions236a,236bboth reside in the second region240(on the same side of the clip220) when the door is closed.

FIG. 7Ashows that the first and second protrusions236a,236bneed not be identical. For example, it can be advantageous for the first protrusion236ato have a triangular cross-section, as viewed from the lingual direction. For example, orienting the first protrusion236asuch that a vertex of the triangle points toward the entrance to the recess222can reduce the force required to assemble the door210to the body204. As an added benefit, once the clip220has been assembled to the body204, a side surface of the triangular first protrusion236acan flatly engage the gingival-facing surface of the clip220to prevent accidental disassembly of the door210. The first protrusion236acan thus have a shape allowing easy passage through the clip220in the gingival direction but not the occlusal direction. By contrast, the second protrusion236bhas a substantially round cross-section to enable reversible passage of the second protrusion236bthrough the clip220in gingival and occlusal directions.

Once again, the process of opening and closing the door210can be made reversible because of the resilient nature of the clip220. As the treating professional imparts occlusal and gingival forces to open and close the door210, the mesial and distal sections252,254elastically spread in directions away from each other, thereby allowing the second protrusion236bto toggle between residing in the first and second regions238,240, respectively.

FIG. 9shows another appliance300with its door (hidden inFIGS. 9-10for clarity). Like previous appliances, the appliance300has a base302having an underlying bonding surface306, body304, and recess322on the outward facing side of the body304. Received in the recess322, however, is a resilient planar clip320having a generally “U”-shaped configuration. A protrusion336is also received in the recess322, and can be integral with the door, or a discrete component partially embedded in the door as previously described and shown in the appliance100ofFIG. 4A.

FIG. 10shows the interaction between the protrusion336and the clip320in more detail. As shown, the clip320has a center section350and a pair of arm sections352,354. The arm sections352,354include respective inward-facing projections334that divide the space enclosed by the sections350,352,354of the clip320into gingival and occlusal regions338,340. InFIGS. 9 and 10, the protrusion336resides in an equilibrium position within the gingival region338, corresponding to the closed position of the door. When there is sufficient applied force urging the door toward a generally occlusal direction, the associated protrusion336causes the arm sections352,354to elastically deflect in respective mesial and distal directions, allowing the protrusion336to slide past the opposing projections334until it fully resides in another equilibrium position within the occlusal region340, corresponding to the opened position of the door. Being resilient, the arm sections352,354can return toward their original relaxed states and retain the protrusion336in the region340.

Referring again toFIG. 9, the deflection of clip320occurs along a reference plane that is generally coplanar with the clip320itself. This reference plane is also parallel to both a bottom wall328of the recess322and an underlying bonding surface306of the base302. Advantageously, such a configuration can help decrease the facial-lingual profile of the appliance, because the recess322and the clip320therein can be made relatively thin. The ease by which the protrusion336slides between the regions338,340can be adjusted based on the cross-sectional dimensions of the sections350,352,354and the size and shape of the inwardly-facing projections334. The mechanism whereby the clip320engages and disengages with the protrusion336is optionally similar to the mechanisms described in U.S. Pat. No. 6,302,688 (Jordan et al.) and U.S. Pat. No. 6,582,226 (Jordan et al.), except the clip320here engages a sliding door rather than an archwire.

It is to be understood that many other aspects of appliance300may have similar form and function to those described in appliances100,200and these will not be repeated.

Optionally, any of the appliances100,200,300could use a clip120,220,320that exerts a continuous force on the protrusion136,236a,236b,336. Preferably, this force is a compressive force, resulting from the clip120,220,320being maintained in a partially stressed (i.e. unrelaxed) state. This can be achieved by using a protrusion that is over-sized. For example, the cross-sectional diameter of the protrusion136,236a,236b,336could be made intentionally larger than at least some of the regions138,140,238,240,338,340. This feature can provide a snug fit between the door110,210and the body104,204,304and preventing the door110,210from rattling while engaged to the body104,204,304.

Having a clip that exerts a continuous force on the protrusion can be of particular benefit when dealing with appliances in which there are significant gaps between the door and the body. As mentioned previously, gaps are sometimes desirable to facilitate sliding of the door and avoid binding. Additionally, such gaps can also help provide sufficient space on the mesial and distal sides of the door to allow for mesial-distal debonding of the appliance from the tooth at the end of treatment. In some embodiments, the assembled door and body have a pre-determined cumulative mesial-distal gap width of at least about 25 micrometers (1 mil), at least about 38 micrometers (1.5 mils), or at least about 51 micrometers (2 mils); in some embodiments, the gap width is up to about 130 micrometers (5 mils), up to about 100 micrometers (4 mils), or up to about 76 micrometers (3 mils).

FIGS. 11 and 12are exploded views showing an appliance400according to another embodiment. The appliance400has many features in common with those already described, including a base402, a body404joined to the base402, and an archwire slot408extending across the body404. The appliance400further includes a door410slidably received in the body404and having an integral protrusion436. The body404has a recess422adjacent the slot408that receives a clip420.

As shown alongside the door410inFIG. 13A, the exemplary clip420has an asymmetric configuration when viewed from the mesial or distal direction. The clip420is planar and resides in a reference plane generally perpendicular to the mesial-distal axis of the appliance400. Further, the clip420includes a center section460, an arched section462, and a tail section464. The center section460is approximately linear and extends adjacent and parallel to a bottom wall428of the recess422. In a preferred embodiment, the center section460flatly engages the bottom wall428and does not significantly move relative to the recess422during normal operation of the door410.

The arched section462of the clip420is joined to the gingival end of the center section460and extends toward the occlusal direction, whereby the arched section462forms a generally “U” shaped configuration with respect to the center section460. The arched section462has an arch466that is located near the geometric midpoint between the occlusal and gingival edges of the clip420. This exemplary arch466is characterized by a convexity on the facial surface of the arched section462, and the arch466faces a generally facial direction when received in the recess422of the body404. As shown inFIGS. 6-8, the arch466and protrusion436oppose each other when the appliance400is assembled.

The tail section464of the clip420is joined to the occlusal end of the center section460and extends in a generally facial-gingival direction such that the tail section464forms an acute angle α (shown inFIG. 13B) relative to the center section460when relaxed. In some embodiments, the angle α formed between the tail section464and the center section460is at least about 45 degrees, at least about 50 degrees, or at least about 70 degrees when the clip420is relaxed. In some embodiments, the angle formed between the tail section464and the center section460is up to about 90 degrees, up to about 85 degrees, or up to about 75 degrees when the clip420is relaxed.

Optionally and as shown, the tail section464has a cross-sectional dimension that varies along its length. In this embodiment, the tail section464has a cross-sectional dimension that monotonically decreases with increasing distance from the center section460, and is thinnest at its terminal end461. Tapering the tail section464in this manner increases the overall flexibility of the section464relative to the remaining sections460,462. This can provide certain functional advantages for the clip420, as will be discussed in the following sections.

Referring now toFIG. 13B, the terminal end461, arch466, and gingival side wall426(of the recess422) are linearly spaced apart from each other along an occlusal-gingival axis and collectively define certain regions where the protrusion436may reside. When located in the position labeled “A,” the protrusion436is on the occlusal side of the terminal end461, arch466, and gingival side wall426. In this position, the door410is still disassembled from the body404and can freely slide in the occlusal direction along an enlarged opening470located on the occlusal side wall of the recess422(shown inFIG. 11). Because the opening470is wider than the protrusion436along the mesial-distal direction, the door410can continue sliding in the occlusal direction until the door410is dislodged from the body404.

When sufficient force is applied to the door410in a generally gingival direction, the protrusion436presses against the terminal end461, causing it to deflect downwards (i.e. in a lingual direction) and permit the protrusion436to “snap” into the position labeled “B.” In this position, the protrusion436is now on the gingival side of the terminal end461and the occlusal side of the arch466and the gingival side wall426. Here, the protrusion436is constrained in an equilibrium position between the terminal end461and the arch466, which collectively define an occlusal region440. The appliance400is now in assembled form, with the door410in its opened position.

From this configuration, additional force can be applied to the door410in a gingival direction to close the door410. Upon reaching a threshold amount of force, the arched section462resiliently “flattens” to allow passage of the protrusion436into its third position, labeled “C” inFIG. 13B. In this position, the protrusion is located on the gingival side of both the terminal end461and arch466but on the occlusal side of the gingival side wall426. Here, the protrusion436is constrained in a second equilibrium position between the arch466and the gingival side wall426, which collectively define a gingival region441. With the protrusion436now in the gingival region441, the door410is closed. The arched section462springs back toward its original position to retain the protrusion436and prevent the door410from spontaneously opening. While there is an opening471on the gingival side wall426that divides the appliance400to facilitate debonding, the mesial-distal width of the opening471is less than that of the protrusion436, thus preventing further gingival movement of the door410.

In at least some embodiments, the tail section464acts as a pawl that facilitates assembly of the door410to the body404while preventing accidental disassembly. This advantage is enabled by the orientation of the tail section464, which is slanted toward a slightly gingival direction as shown, for example, inFIG. 13A. When the protrusion436presses against the tail section464, there is sufficient clearance on the gingival side of the tail section464for it to resiliently bend toward the center section460and permit passage of the protrusion436over the tail section464and into region “B” within the recess422. Once the protrusion436has entered region “B,” however, it cannot then easily escape from the recess422because of the gingival slant in the tail section464. Moreover, the occlusal side wall426′ of the recess422constrains the tail section464from deflecting significantly in the occlusal direction. As a result of these features, the assembly of the door410to the body404can be made substantially irreversible.

FIGS. 14-19illustrate an appliance500according to another embodiment similar in many respects to those shown inFIGS. 11-13B, but with additional options and advantages. As shown inFIGS. 14 and 15, the appliance500has a base502, a body504extending from the base502, and an archwire slot508extending across the body504in a generally mesial-distal direction. The appliance500further includes a door510that is slidably engaged to the body504and toggles between a slot open position where the slot508is accessible and a slot closed position where the slot508is not accessible.

The door510is a “wide door” differing from those previously shown because it has a mesial-distal width that substantially matches the overall mesial-distal width of the overall appliance500. Advantageously, this feature can provide enhanced rotational control during orthodontic treatment (affecting rotational movement of the tooth about its long axis), since it increases the distance along which an archwire can engage, and apply therapeutic forces to, the door510of the appliance500. Here, the door510has inward-facing rails511protruding in mesial and distal directions and longitudinally extending across the door510in a generally occlusal-gingival direction. As shown, the rails511are received in complementary grooves513located on mesial-facing and distal-facing surfaces of the body504. Together, the rails511and grooves513guide the operative sliding motion of the door510.

Referring toFIG. 16, the body504also has an elongated recess522that is located adjacent the slot508and receives an integral, resilient clip520. Similar to the clip420in appliance400, the clip520is substantially coplanar with a reference plane perpendicular to the mesial-distal longitudinal axis of the slot508and generally bisecting the appliance500into mesial and distal halves. Referring now to the cross-sectional view ofFIG. 19, the clip520is held captive in the recess522by occlusal and gingival walls526, bottom wall528, and the door510.

When the door510is in its closed position, the slot508is enclosed by four substantially rigid walls. Optionally and as shown inFIGS. 17-18, the slot508has a bottom wall that is collectively defined by both a partial bottom wall570alocated on the body504and a pair of partial bottom walls570blocated on the door510. The partial bottom walls570bextend along mesial and distal portions of the slot508, and straddle the partial bottom wall570a, which extends along a central portion of the slot508. Similarly, the slot508includes an occlusal wall collectively defined by a partial occlusal wall572aon the body504and a pair of partial occlusal walls572bon the door510that straddle the partial occlusal wall572a. In this particular embodiment, the slot508has a facial wall574defined exclusively by the door510and a gingival wall576exclusively defined by the body504.

One benefit of the configuration described above is the lengthened interface between the rails511and respective grooves513. More specifically, this mechanism allows the rails511and groove513to effectively traverse not only the gingival half of the appliance500but also the occlusal-gingival width of the slot508. By increasing the occlusal-gingival length along which these mating surfaces engage each other, this configuration enhances stability, and reduced wobbling, of the door510as it slides open and closed along the body504. This is especially useful where the appliance500is made as small as possible for patient comfort and space on the body504is limited.

The clip520, including a center section560, an arched section562, and tail section564, has substantially the same form and function as the clip420of appliance400. Optionally and as shown inFIGS. 18 and 19, however, the clip520includes an extended corner portion521located between the center section560and tail section564that protrudes in a lingual direction toward the bottom wall528of the recess522. The bottom wall528of the body504also includes a cavity523that precisely registers with and receives the corner portion521when the clip520is seated in the recess522. As shown inFIG. 19, the cavity523advantageously anchors the clip520to the body504, creating a reaction force that prevents the clip520from rotating, even when excessive opening forces are applied to the door510.

The presence of the corner portion521can provide a more robust appliance500in view of both operator misuse and manufacturing variability. For example, if a treating professional forcefully attempts to slide the door510in the occlusal direction even after the door510is fully open, the corner portion521contacts the gingival (i.e. occlusal-facing) wall of the cavity523. The gingival wall of the cavity523thus acts as a positive stop that keeps the clip520from toppling counterclockwise out of the recess522. Since the clip520is restrained from rotation, overextension of the door510is prevented as the tail section564interferes with further occlusal movement by a protrusion536on the door510. This independent interaction between the corner portion521and cavity523, while not essential, helps increase tolerance for small gaps that may be present between the door510and body504, variability in the shape of the clip520, and other minor manufacturing irregularities.

Other aspects of the appliances400,500are analogous to those previously described and do not need repeating for the skilled person.

FIGS. 20-25illustrate another exemplary embodiment that uses a non-unitary retention member (i.e. one including at least two discrete components).FIG. 20shows a partial appliance600having a base602, a body604, and archwire slot608. The body604has a compound recess622that includes a central channel680extending in a generally occlusal-gingival direction and closed-ended lateral channels682,684, each extending in a generally mesial-distal direction across the central channel680. The appliance600uses a clip620having a rectangular beam620aand round beam620bheld captive within respective lateral channels682,684. The appliance600also includes an integral door610shown inFIG. 21. The door610has a protrusion636that is in registration with the central channel680when the door610is assembled to the body604. The door610has rails enabling it to slide in occlusal and gingival directions along substantially matching grooves located on the body604.

The rectangular beam620ais adjacent the occlusal entrance to the recess622. The round beam620b, on the other hand, is remote from the occlusal entrance to the recess622, being spaced from the beam620atoward the gingival direction. As further shown in the cross-sectional view ofFIG. 23, the long cross-sectional dimension (width) of the rectangular beam620aextends along an axis oriented at a slight acute angle θ relative to the sliding direction the door610. In some embodiments, the angle θ is at least about 0.1 degrees, at least about 0.5 degrees, or at least about 1 degree. In some embodiment, the angle θ extends up to about 90 degrees, up to about 45 degrees, or up to about 10 degrees. Optionally and as shown inFIG. 23, the angle θ can be built into the bottom surface of the lateral channel682in which the beam620aresides.

By virtue of this relative arrangement of the beams620a,620b, the protrusion636first traverses the rectangular beam620a, then traverses the round beam620bas it is slidably assembled to the body604. In the assembly of the door610, each beam620a,620bindependently functions as a latch by resiliently deflecting toward the bottom surface of the recess622to permit passage of the protrusion636as the associated door610is urged in a gingival direction against the beam620a,620b. As the protrusion636slides toward an equilibrium position on the opposite side of the beam620a,620b, the beam620a,620bflexibly returns toward its original shape, thereby preventing the door610from easily sliding back across the beam620a,620b. The door610can be reversibly opened and closed, as shown inFIGS. 24 and 25, by sliding the protrusion636back and forth between regions on the occlusal and gingival sides of the round beam620b.

Optionally, one or both beams620a,620bcould have a curved configuration along some or all of its length. For example,FIG. 22shows a beam620cis provided with a dimple625approximately located at the midpoint of the beam620c. The dimple625provided in one or both beams620a,620bcan increase the clearance required for the protrusion636to pass over the beams620a,620band accommodate manufacturing tolerances in the height of protrusion636and the mating surfaces between the door610and the body604.

The rectangular beam620ahas a geometry and orientation that facilitates the assembly of the door610to the body604, while also preventing spontaneous or inadvertent separation of the door610from the body604when a treating professional normally opens and closes the door610.FIG. 23shows the door610located in a region of the recess622between the rectangular and round beams620a,620b. In this figure, the door610is subjected to a force vector in the occlusal (opening) direction. Because of the slight tilt in the beam620a, a gingival-facing surface of the beam620aflatly engages an occlusal-facing surface of the protrusion636. The gingival-facing surface of the beam620atherefore acts as a positive stop that impedes passage of the protrusion636over the beam620ain the occlusal direction. As a further benefit, the tilt in the beam620aalso acts as a ramp that assists with the initial assembly of the door610in the body604.

In some embodiments, the geometry of the protrusion636can also be tailored to adjust the forces required to open and close the door610. As shown inFIG. 21, for example, the opening and closing forces can be generally decreased by using a protrusion636having a generally trapezoidal profile (as viewed from the mesial or distal direction) and having a suitable side wall angle β. In some embodiments, the side wall angle β is less than about 45 degrees, less than about 35 degrees, or less than about 30 degrees. Conversely, the opening and closing forces can be increased by using a side wall angle β greater than about 45 degrees, greater than about 55 degrees, or greater than about 60 degrees. If desired, asymmetric opening and closing forces can be realized by using a trapezoidal protrusion636with substantially different side wall angles (e.g. β1and β2). For example, the leading (or gingival-facing) edge of the protrusion636could have a side wall angle of 40 degrees, while the trailing (or occlusal-facing) edge of the protrusion636could have a side wall angle of 60 degrees. Such a configuration allows threshold opening forces to be intentionally increased, preventing the door610from accidently opening during mastication.

The forces of opening and closing the doors are determined by the material properties, protrusion dimensions and the cross-sectional dimensions of the beams620a,620b. Preferably, the beams620a,620bare short wire segments of a superelastic nickel-titanium alloy. In one exemplary embodiment, the round beam620bhas a diameter of 0.20 millimeters (0.008 inches) while the rectangular beam620ahas “A” and “B” dimensions of 0.15 millimeters and 0.25 millimeters (0.006 inches and 0.010 inches), respectively. In this embodiment, the beams are 1.22 millimeters (0.048 inches) long. The protrusion636has a height of 0.20 millimeters (0.008 inches) and an area of 0.356 millimeters×0.25 millimeters (0.014 inches×0.010 inches). The clearance between the door610and the body604is about 19 micrometers (0.00075 inches) on all surfaces.

Still another embodiment is provided by the appliance700engaging exemplary archwire50′, as illustrated inFIGS. 26 and 27. The appliance700is essentially the same as the appliance600in most respects, but uses a unitary clip720residing in a recess722of a body704, and a door710with gingival and occlusal protrusions736aand736b. The protrusions736a,736bengage the clip720as the door710is assembled to the body704. Here, the protrusion736btoggles between regions on the gingival and occlusal sides of the clip720, corresponding to closed and open door configurations, respectively. The protrusion736ais provided with an asymmetric trapezoidal configuration to prevent accidental disassembly of the door710from the body704in normal operation.

The appliance doors embodied above preferably have force characteristics that enable the treating professional to easily open and close the door using a common orthodontic hand instrument, such as an orthodontic explorer. Optionally, a specialized hand instrument could be used to limit the sliding motion of the door; for example, a flat probe could be inserted in the seam between the leading edge of the door and the body, and then twisted to open the door. This could help reduce the risk of accidental debonding. In some embodiments, the threshold force used to open the door is at least about 50 gram-force, at least about 200 gram-force, or at least about 500 gram-force. In some embodiments, the threshold force used to open the door is up to about 5000 gram-force, up to about 3000 gram-force, or up to about 1000 gram-force.

FIGS. 28-30show an appliance800engaging an exemplary archwire50″ in yet another embodiment, the appliance800having a base802, a body804, and a door810. Like in appliance500previously described, the door810has a pair of inwardly protruding rails811that slide along a pair of grooves813located on respective mesial-facing and distal-facing sides of the body804. As shown inFIG. 30, the door810passes over a generally cross-shaped recess822retaining a resilient clip820having a mode of operation similar to that of clip720, where a protrusion (not visible) extending in a lingual direction from the door810causes the clip820to resiliently deflect when toggling the door810between opened and closed positions and a second protrusion (not visible) extending in a lingual direction from the door810prevents the door810from falling out when the door810is in an open position.

Optionally, the door810has an overall mesial-distal width that is slightly smaller than the mesial-distal width of the body804to facilitate squeeze-debonding the appliance800. In the process of squeeze-debonding, compressive forces provided by a hand instrument will be concentrated on the body804rather than the door810, enabling the appliance to collapse properly. The difference in the mesial-distal dimension between the door810and body804can range, for example, from about 0.051 millimeters (0.002 inches) to about 0.254 millimeters (0.010 inches).

Referring again toFIG. 30, the appliance800differs from previous appliances in that it includes a pair of rigid integral walls890that partially define an archwire slot808for accommodating the archwire50′″. The integral walls890are located gingival and adjacent to the recess822and define a majority of the gingival wall of the archwire slot808. The remaining portions of the gingival wall of the archwire slot808are provided by a pair of gingival-facing surfaces892of the door810, as shown. The gingival-facing surfaces892are located adjacent the mesial and distal sides of the appliance800. Advantageously, the integral walls890can provide for more secure ligation by allowing the archwire50′″ to impart substantial torque (i.e. twisting forces) to the appliance800without undesirably opening the door810.

In some embodiments, the integral walls890extend along at least about 40 percent, at least about 45 percent, at least about 50 percent, at least about 55 percent, or at least about 60 percent of the archwire slot808. In some embodiments, the integral walls890extend along at most about 90 percent, at most about 85 percent, at most about 80 percent, at most about 75 percent, or at most about 70 percent of the archwire slot808.

As further shown inFIG. 30, the leading edge823of door810engages a complementary recess825next to the gingival wall of the archwire slot808as the door810is slidably moved into its closed position. Engagement of the convex leading edge823with the mating complementary recess825helps limit undesirable movement of the door810that can result from the clearance between the door810and body804when the appliance800is subjected to rotation relative to the occlusal-gingival axis or labial movement in the labial direction of the archwire50′″.

FIGS. 31-33show an appliance900in disassembled and assembled views according to yet another exemplary embodiment. This embodiment further develops the concept of an integral wall aligned along the gingival side of an archwire slot908and includes a feature to facilitate operation of the ligating mechanism. The appliance900bears essentially the same features as those of appliance800, but includes a wall990that is integral with the appliance body and defines the gingival (or occlusal-facing) side of the archwire slot908. In a preferred embodiment, the wall990extends along essentially the entire mesial-distal length of the archwire slot908. Advantageously, the archwire slot908is highly rigid, since each of the three sides of the archwire slot908is substantially defined by the body of the appliance900along the mesial-distal length of the archwire slot.

The appliance900includes a door910akin to that of appliance800, but a gingival-facing surface992of the door910flatly abuts an opposing occlusal-facing surface994of the wall990when the door910is in its closed position as shown inFIGS. 32-33.

Having the wall990extend along the mesial-distal length of the archwire slot908is significantly advantageous because it prevents a ligated archwire from imparting significant occlusal or gingival (i.e. sliding) forces to the door910. As shown inFIGS. 31-33, the archwire slot908is bounded on three of its four sides by the appliance body, and each of the three sides extends essentially along the entire mesial-distal length of the archwire slot. On the fourth side, only the labial-facing side of the door910can contact an archwire captured in the archwire slot908. Consequently, there is great freedom for the archwire to deliver substantial tipping and torque forces to the appliance900while avoiding the possibility of the door910unexpectedly opening during the course of treatment.

The wall990, as shown, has generally parallel opposing walls facing occlusal and gingival directions. As an option however, the wall990could be tapered or thickened along some regions to increase strength. For example, the mesial and distal ends of the wall990could have greater occlusal-gingival thickness relative to the thickness along centrally located areas of the wall990. In some of these embodiments, the mating surfaces992,994could extend along a curved topology in an interlocking configuration to help prevent wobbling of the door910when closed.

As an added optional feature, the appliance900includes a rectangular recess996, located at the seam between the leading, occlusal edge of the door910and appliance body. The recess996allows for insertion of a suitable flat-ended hand instrument to assist in opening of the door910. Once inserted, the instrument can be rotated 90 degrees about its long axis, thereby operating as a cam for slidably opening the door910. In the embodiment shown, the occlusal edge of the door910(bounding the recess996) tapers to a pre-defined engagement surface911that extends along a mesial-distal direction adjacent the bottom of the recess996. The engagement surface911is suitably positioned to enable the instrument to transmit forces to slide the door910open and avoid transmitting a moment which could cause the door910to rotate and/or jam.

Options and advantages broadly related to this concept are disclosed, for example, in U.S. Pat. No. 6,506,049 (Hanson) and U.S. Patent Publication No. 2009/0004618 (Oda, et al.).

Referring toFIG. 31, the appliance900further includes a beam920having functional features related to that of the beam720in the appliance700. In a manner similar to the beam720, the beam920mechanically interacts with a pair of protrusions (not visible) situated on the lingual-facing side of the door910to toggle the door between open and closed positions, while also preventing the door920from becoming accidently disengaged from the rest of the appliance900. Optionally and as shown, the beam920has a generally rectangular cross-section with rounded corners. In this embodiment, the rounded corners have radii such that two of the four sides of the cross-section are curved across essentially their entire length, thereby facilitating the opening and closing of the door920. The beam920is also oriented at a characteristic tilt angle, as described previously with respect to beam620a.

Further aspects concerning the configuration and operation of the appliances800,900are generally analogous to those of appliances already described (e.g. appliances500,600,700) and will not be revisited here.

Kits and assemblies of the appliance described are also contemplated herein. For example, one or more of the appliances described herein may be pre-coated with a suitable orthodontic adhesive and packaged in a container or a series of containers, as described for example in U.S. Pat. No. 4,978,007 (Jacobs et al.); U.S. Pat. No. 5,015,180 (Randklev); U.S. Pat. No. 5,429,229 (Chester et al.); and U.S. Pat. No. 6,183,249 (Brennan, et al.), and U.S. Patent Publication No. 2008/0286710 (Cinader et al.) As another option, any of these appliances could also be used in combination with a placement device allowing for indirect bonding to the patient, as described in U.S. Pat. No. 7,137,812 (Cleary, et al.).

As a further option, any of the above appliances may include an archwire slot that has opposing sidewalls that are tapered to enhance torque strength, as described in pending provisional U.S. Patent Application Ser. No. 61/545,361 (Yick et al.).

Additional embodiments of the present invention are herein enumerated as follows:

A. An orthodontic appliance comprising: a base; a body extending outwardly from the base; an archwire slot extending across the body in a generally mesial-distal direction; a recess located on the body adjacent the archwire slot; a retention member received in the recess, the retention member dividing the recess into at least first and second regions; and a door slidably engaged to the body and having a protrusion, the protrusion extending into the first region when the door is open to allow access to the archwire slot and extending into the second region when the door is closed to prevent access to the archwire slot.

B. The appliance of embodiment A, wherein the recess has a bottom wall and opposing first and second side walls.

C. The appliance of embodiment A or B, the retention member comprising: a first beam; and a second beam spaced apart from the first beam along a generally occlusal-gingival direction, wherein each beam extends along a generally mesial-distal direction, the first region is located between the first and second beams, and the second region is located on the occlusal or gingival side of both the first and second beams.

D. The appliance of embodiment C, wherein the first beam has a generally rectangular cross-section and the second beam has a generally circular cross-section.

E. The appliance of any one of embodiments A-D, wherein at least one beam has a generally curved configuration along its longitudinal direction.

F. The appliance of embodiment A or B, wherein the protrusion is a first protrusion and wherein the door further comprises a second protrusion spaced from the first protrusion along the sliding direction of the door, whereby the first and second protrusions reside in respective second and first regions when the door is open and the first and second protrusions both reside in the second region when the door is closed.

G. The appliance of any one of embodiments A-F, wherein the archwire slot is bounded along three sides in a generally rectilinear configuration, each side substantially defined by the body along the mesial-distal length of the archwire slot.

H. An orthodontic appliance comprising: a base; a body extending outwardly from the base; an archwire slot extending across the body in a generally mesial-distal direction; a recess located on the body adjacent the archwire slot, the recess having a bottom wall and opposing first and second side walls; a retention member received in the recess; and a door slidably engaged with the body and having a protrusion extending into the recess, the retention member resiliently deflecting to toggle the protrusion between a first position wherein the door is open to allow access to the archwire slot and a second position wherein the door is closed to prevent access to the archwire slot.

I. The appliance of embodiment A, B, G, or H, the retention member further comprising: a center section extending along the bottom wall and having first and second ends; an arched section joined at the first end; and a tail section joined at the second end and extending at an acute angle relative to the center section, the first position located between the first side wall and the arched section, and the second position located between the arched section and the second side wall.

J. The appliance of embodiment A, B, G, or H, wherein the retention member is generally coplanar with the bottom wall and resiliently deflects in a direction transverse to the sliding direction of door.

K. The appliance of embodiment J, wherein the retention member has a generally “U”-shaped configuration.

L. The appliance of embodiment J or K, wherein the retention member further comprises a pair of interior side surfaces and a pair of opposing inward-facing projections disposed on the side surfaces between the first and second regions.

M. An orthodontic appliance comprising: a base; a body extending outwardly from the base;

an archwire slot extending across the body in a generally mesial-distal direction; a recess located on the body adjacent the archwire slot, the recess having a bottom wall and opposing first and second side walls; a retention member received in the recess, the retention member comprising: a center section extending along the bottom wall and having first and second ends; an arched section joined to the first end and having an apex; and a tail section joined to the second end and extending at an acute angle relative to the center section; and a door slidably engaged with the body and having a protrusion extending into the recess, wherein the protrusion resides between the first side wall and the arched section when the door is open to allow access to the archwire slot and the protrusion rests between the arched section and the second side wall when the door is closed to prevent access to the archwire slot.

N. The appliance of any one of embodiments B-M, the recess further comprising opposing third and fourth side walls, wherein the first, second, third, and fourth side walls retain the retention member and constrain sliding of the retention member in directions generally parallel to the bottom wall.

O. The appliance of any one of embodiments A-N, wherein the retention member comprises a shape memory alloy.

P. The appliance of any one of embodiments A-O, wherein the retention member is a unitary component.

Q. The appliance of any one of embodiments A-P, wherein each of the base, body, and door comprises a translucent ceramic material.

R. The appliance of any one of embodiments A-Q, wherein the door and protrusion are a unitary component.

S. The appliance of any one of embodiments A-R, wherein the protrusion has a generally planar front face and back face, the front and back faces being oriented at different angles relative to the bottom wall of the recess.

T. The appliance of any one of embodiments I and M-S, wherein the center section, arched section, and tail section are integral components of the retention member.

U. The appliance of any one of embodiments I and M-T, wherein the tail section has a cross-sectional dimension that generally decreases with increasing distance from the center section.

V. The appliance of any one of embodiments A-U, wherein the body has an opening in communication with both the recess and an exterior of the appliance, the opening being sufficiently sized to enable passage of the protrusion through the opening and into the recess when assembling the door to the body.|

W. The appliance of any one of embodiments I and M-V, wherein the spacing between the arched section and the opposing side walls is sized whereby the retention member is maintained in a state of compressive stress.

X. The appliance of any one of embodiments A-W, wherein the body further comprises a pair of opposing grooves, and the door comprises a pair of rails slidably received in the pair of grooves.

Y. The appliance of embodiment A-X, wherein the door has a mesial-distal width that substantially matches the overall mesial-distal width of the appliance.

Z. A method of assembling an orthodontic appliance having ceramic body, a ceramic door having a protrusion, and a retention member, the method comprising: placing the retention member into a recess located in the body; slidably engaging the door along a pair of rails disposed on the body until the protrusion contacts an exterior surface of the retention member; and urging the door against the retention member until the protrusion is received within a region of the recess that is at least partially defined by the combination of the recess and an interior surface of the retention member.

AA. The method of embodiment Z, wherein the retention member comprises a pawl that resiliently deflects to enable assembly of the door to the body and subsequently engages a side wall of the recess to prevent spontaneous disassembly.

All of the patents and patent applications mentioned above are hereby expressly incorporated into the present description. The foregoing invention has been described in some detail by way of illustration and example for purposes of clarity and understanding. However, various alternatives, modifications, and equivalents may be used and the above description should not be taken as limiting in the scope of the invention which is defined by the following claims and their equivalents.