1. Field of the Invention
Orthodontic devices, assemblies and methods are provided for use in orthodontic treatment. More particularly, orthodontic corrector devices, along with related assemblies and methods, are provided for directing therapeutic forces between dental structures within the oral cavity.
2. Description of the Related Art
The field of orthodontics relates to the supervision, guidance and correction of teeth towards proper positions in the oral cavity. Orthodontic therapy generally involves the application of forces to move teeth into a proper bite configuration, or occlusion. One mode of therapy, known as fixed appliance treatment, is carried out using a set of tiny slotted appliances called brackets, which are affixed to the anterior, cuspid, and bicuspid teeth of a patient. In the beginning of treatment, a resilient orthodontic appliance known as an archwire is received in each of the bracket slots. The end sections of the archwire are typically anchored in appliances called buccal tubes, which are affixed to the patient's molar teeth.
When initially installed in the brackets and buccal tubes, the archwire is deflected from its original arcuate (or curved) shape, but then gradually returns to this shape during treatment. In this manner, the archwire applies gentle, therapeutic forces to move the teeth from improper positions to proper positions. Taken together, the brackets, buccal tubes, and archwire are commonly referred to as “braces”. Braces are often prescribed to improve dental and facial aesthetics, bite function and dental hygiene.
During certain stages of treatment, additional intraoral appliances may be prescribed for use in conjunction with fixed appliances to correct particular kinds of malocclusions. For example, some appliances are used to correct Class II malocclusions, such as an overbite where the mandibular first molars are located excessively distal (in the rearward direction) with respect to the maxillary first molars when the jaws are closed. Other appliances remedy an opposite malocclusion, known as a Class III malocclusion, such as an underbite where mandibular first molars are located excessively mesial (in the forward direction) with respect to the maxillary first molars when the jaws are closed.
In recent years, Class II and Class III correctors have been developed that are installed by the orthodontist and require minimal patient intervention during the course of treatment. These devices advantageously correct Class II and Class III malocclusions without need for patient compliance. Moreover, there are various possibilities in connecting these devices to the dental arch. Banded headgear tubes are still commonly used to provide a distal connection to the upper dental arch. These banded appliances, however, are not universally used. Bondable molar appliances are more convenient to use in many respects and some orthodontists prefer them over banded appliances. As another option, connection to the dental arch may be made indirectly by coupling the intraoral device to one or both archwires. Accordingly, manufacturers have sought to configure these intraoral devices with the versatility to work with a wide variety of appliances.
Provided herein is an intraoral orthodontic corrector, along with related assemblies and methods, that direct corrective forces to dental structures while displaying substantially improved robustness during the course of treatment.
While prior art devices have attempted to connect intraoral appliances to bonded appliances, these efforts often exposed their vulnerabilities to breakage or bond failure as a result of mastication (biting) forces inadvertently transmitted to the appliance. The risk of bond failure is also generally higher in these situations since bonded appliances tend to be significantly weaker than their banded counterparts. Moreover, these prior art devices tend to use couplings that provide a high degree of pivotal freedom between adjacent components. While these couplings advantageously allow normal jaw movement by the patient, these same couplings can also be problematic in at least two other ways.
First, the freedom provided by the coupling can allow portions of the device to inadvertently pivot into the occlusal areas. This, in turn, can result in the patient biting down on the device thereby causing bond failure, device breakage and/or painful contact of the device with the oral tissues of the patient. Second, even if the device is kept safely away from the occlusion, the couplings can still bind or jam when misaligned or otherwise knocked out of position by hard food objects and the like. When this occurs, the biting force can become transmitted directly to the coupling and again cause device breakage or bond failure.
The provided orthodontic corrector overcomes these problems by including a flexible cantilever that isolates adjoining device components from the brunt of these biting forces. By resiliently flexing, or deflecting, in response to inadvertent forces placed on the device, vulnerable components of the device are protected. When these forces are subsequently removed, the cantilever returns to its original orientation and thereby maintains the proper alignment of the corrector. As an additional advantage, the cantilever can allow the position of the force module to be extended toward the distal direction and enable a greater range of connection options between the force module and the dental arch.
In one aspect, the present invention is directed to an orthodontic corrector for applying therapeutic forces between an upper arch appliance and a lower arch appliance comprising a connector for coupling to the upper arch appliance of a patient, a cantilever rigidly coupled to the connector, the cantilever comprising a resilient material having sufficient memory to self-return the cantilever to a certain, pre-determined orientation when relaxed, and a force module having two opposing ends, with one end coupled to the cantilever and the opposite end adapted for coupling to the lower appliance.
In another aspect, the invention is directed to an orthodontic assembly comprising a set of brackets, an archwire connected to the brackets, a connector coupled to the archwire, a cantilever rigidly coupled to the connector and comprising a resilient material having sufficient memory to self-return the cantilever to a certain, pre-determined orientation when relaxed, and a force module coupled to the cantilever.
In still another aspect, the invention is directed to a method of applying forces between first and second orthodontic appliances located on opposing jaws of a patient comprising providing a connector, the connector rigidly attached to one end of a cantilever comprising a resilient material having sufficient memory to self-return the cantilever to a certain, pre-determined orientation when relaxed, the other end of the cantilever being pivotally attached to a force module, coupling the connector to the first appliance, and coupling the force module to the second appliance, wherein the cantilever flexibly maintains at least a portion of the force module in a location that is fixed relative to the connector.
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.
The present disclosure relates to orthodontic devices, correctors, and assemblies that apply therapeutic forces to dental structures during the course of treatment. Exemplary embodiments of these devices, correctors, and assemblies shown herein are useful for treatment of Class II malocclusions. However, these should not be deemed to unduly limit the invention. For example, these embodiments could also be adapted for use in treating class III malocclusions. Alternatively, these embodiments could be adapted for use within either the upper or lower arch individually.
Bonded orthodontic appliances are affixed to the respective teeth of both the upper and lower arches. Appliances attached to the upper arch include upper brackets 30 and upper buccal tube 32. Similarly, appliances attached to the lower arch include lower brackets 40 and lower buccal tube 42. As shown in
Each of the upper appliances is connected to an upper archwire 50 and each of the lower appliances is connected to a lower archwire 60. In this example, both upper and lower archwires 50,60 have generally rectangular cross-sections in planes perpendicular to their longitudinal axes. An elastomeric O-ring ligature extends around each of the bracket tiewings to retain the respective archwire 50,60 in its archwire slot. Optionally, the distal ends of the archwires 50,60 are bent as shown in
While not shown, some embodiments of the invention include a mirror image configuration of assembly 100 similarly installed on the left side of the upper and lower dental arches. Such a configuration allows a symmetrical application of forces on both sides of the dental arch.
Orthodontic corrector 102 is part of the assembly 100 which couples the upper archwire 50 to the lower archwire 60. Optionally and as shown here, the corrector 102 is coupled on one end to the upper archwire 50 between the upper bicuspid brackets 30 and the upper buccal tube 32. As used herein, the “end” of a component, such as the corrector 102, shall mean a portion of the component adjacent its outermost end, and shall not be limited, for example, to an outermost end wall of the component. On the opposite end, the corrector 102 is coupled to the lower archwire 60 between the lower cuspid and lower bicuspid brackets 40. In the configuration shown, corrector 102 provides an expansion force bearing against the upper buccal tube 32 and the lower cuspid bracket 40. This expansion force in turn generates a therapeutic force that can correct an overbite by urging the lower dental arch in the forward direction relative to the upper dental arch.
Preferably, the force module 108 is similar in many respects to the bite corrector described in U.S. Pat. No. 5,964,588 (Cleary). As exemplified in
The cantilever 106 is pivotally coupled to the force module 108 at attachment lug 125 which extends outwardly in a gingival direction from the distal end cap 124. At the opposite end of the force module 108, the outer mesial end of the third member 110 is formed into a loop-type configuration as shown in
When the connector 104 is connected to the archwires 50,60 in the manner described, the helical compression spring 122 urges the connector 104 and the third member 110 in directions away from each other. As a result, the connector 104 slides distally along the archwire 50 until it bears against the mesial side of the buccal tube 32, while the third member 110 slides mesially along the archwire 60 until it bears against the distal side of the bracket 40. Other aspects of operating the assembly 100 are similar to those of the appliance described in issued U.S. Pat. No. 6,558,160 (Schnaitter et al.).
The connector 104 and cantilever 106 of the assembly 100 may be used with other types of force modules as well, and its use need not be limited to telescopic force modules such as the force module 108 shown. For example, the cantilever 106 may be coupled to a flat spring made from a shape-memory alloy such as disclosed in issued U.S. Pat. No. 5,752,823 (Vogt). Likewise, the cantilever 106 may be coupled to any other resilient elongated body that is bendable in an arc about references axes perpendicular to its longitudinal axis, such as the force modules described in U.S. Pat. No. 5,651,672 (Cleary).
As shown in these figures, the connector 104 includes a body 130. A pair of central posts 132, a pair of mesial posts 136, and a pair of distal posts 138 protrude outwardly from the body 130 towards a generally lingual direction. The central, mesial and distal posts 132,136,138 present aligned notches 144 which reside between each pair of posts 132,136,138. A pair of elongated grooves 143 extend across the lingual side of the body 130 in directions transverse to the notches 144 and are located in the spaces between the central and mesial posts 132,136 and between the central and distal posts 132,138. Optionally and as shown, the central, mesial and distal posts 132,136,138 are integral with the body 130.
A pair of resilient clips 150 are located in the grooves 143 and held captive by a retaining bar 142, which is received in the aligned notches 144 and extends along generally mesial-distal directions. The notches 144 thereby provide mating surfaces that allow the retaining bar 142 to precisely register with the body 130 when joined. In an exemplary method of assembly, the clips 150 are first placed in the grooves 143 of the body 130, the retaining bar 142 threaded through the clips 150, and finally the retaining bar 142 welded, soldered, or adhesively attached to the mating surfaces of the notches 144. The clips 150 have a mesial-distal width slightly smaller than the width of the grooves 143 to allow the clips 150 to flex freely.
The central, mesial and distal posts 132,136,138 and the retaining bar 142 collectively present an elongated archwire slot 140. As shown in
As seen from the distal direction in
The clips 150 are shown in their normal, relaxed orientations in
Once the archwire 50 is received in the wire-receiving region 154, the inherent resiliency of each clip 150 enables arm portions 152 to spring back toward each other and toward their normal, relaxed configuration as shown in
Also located on the body 130 is an elongated crimpable slot 160, which extends across the body 130 in generally mesial-distal directions. As shown in
Optionally and as shown, the crimpable slot 160 has a slot bottom 162 that is non-parallel with the longitudinal axis of the archwire slot 140. This aspect is particularly shown by
Optionally and as shown in
As further shown in
As an alternative to crimp coupling the connector 104 and the cantilever 106, the two components may be joined by welding, soldering, adhesive bonding, or some other type of mechanical connection.
The cantilever 106 preferably comprises a flexible and resilient material that can withstand a significant amount of bending and twisting in response to forces transmitted from the force module 108 or even hard food objects during mastication. It is further preferable that the resilient material has sufficient memory to self-return the cantilever 106 to a certain, pre-determined orientation when relaxed (i.e. when external forces are removed). As shown here, the pre-determined orientation of the cantilever 106 is a generally straight orientation. Examples of suitable materials include, but are not limited to, shape-memory materials such as nickel-titanium alloys and the like. In exemplary embodiments, the cantilever 106 is made from a flexible wire 170 made from a nickel-titanium superelastic alloy and has a diameter of approximately 0.041 centimeters (0.016 inches).
The flexibility and resilience of the cantilever 106 significantly improve the robustness of both the orthodontic corrector 102 and the orthodontic assembly 100 as a whole. For one, these aspects allow the cantilever 106 to provide a flexible connection between the archwire 50 and the force module 108. Since the cantilever 106 resiliently deflects in a direction laterally of its longitudinal axis when external forces are encountered by the corrector 102, the transfer of mastication forces to the archwire 50 and the connector 104 is reduced. Advantageously, forces transferred to bonded appliances such as the brackets 30,40 and the buccal tubes 32,42 are similarly reduced, leading to fewer bond failures between these appliances and the patient's teeth.
Additionally, when the external forces are removed, the cantilever 106 springs back to its original orientation to ensure that the corrector 102 is once again properly aligned as depicted in
As an added benefit, the cantilever 106 positions the coupling between the loop 172 and the attachment lug 125 of the force module 108 in a location that is distal to the buccal tube 32. This provides a number of further advantages. First, positioning the coupling to the force module 108 distal, as opposed to mesial, to the buccal tube 32 provides a wider range of connection options between the corrector 102 and the lower dental arch. For example, this coupling creates sufficient space for the third member 110 to be alternatively coupled to the lower archwire 60 between the two lower bicuspid brackets 24 if desired by the orthodontist. This in turn can provide a Class II corrector with improved aesthetics since the third member 110 would be further hidden by the patient's cheeks. Even if this option is declined, positioning the coupling distal to the buccal tube 32 provides greater extension of the force module 108, which in turn expands the range of jaw motion over which the compression spring 122 can be activated.
The cantilever 206 is secured against the body 250 by occlusal end cap 207. As shown by phantom lines in
Preferably and as shown, the cantilever 206 extends away from the connector 204 in a generally distal direction. On the distal end of the cantilever 206 is a pivotal joint 211 between the cantilever 206 and the force module 108 (which is identical to the force module 108 described in connection with the embodiment shown in
In some embodiments, the cantilever 206 comprises a resilient polymeric material such as a modified urethane or polyolefin. In alternative embodiments, the cantilever 206 comprises a high modulus elastomer such a highly crosslinked rubber, ethylene-propylene-diene monomer (EPDM) rubber, copolyester elastomer or fluoroelastomer. If additional stiffness or strength is desired, hard organic or inorganic fillers may be blended into the polymeric material. Cantilever 206 is preferably capable of significant twisting and bending deflection. In some embodiments, the cantilever 206 comprises a material having a flexural modulus ranging from 30 to 100 megapascals (4351-14504 pounds per square inch). It is further preferred that the cantilever 206 is durable and does not plastically deform during the course of treatment.
Other components of the assembly 100 and the correctors 102,202 may be manufactured according to any number of methods known to the skilled artisan. These methods include, but are not limited to, milling, investment casting, metal injection molding, and rapid prototyping. If desired, one or more of these parts can also be manufactured from other classes of materials, such as ceramics, polymers, or composites. If polymeric components are used, these may optionally be formed by milling, injection molding, extrusion or rapid prototyping.
In preferred embodiments, the individual correctors 102,202 are manufactured and provided to the orthodontist as a complete set. For example, the manufacturer may pre-assemble the connector 104, cantilever 106, and the force module 108 (excluding the third member 110) to minimize installation time by the orthodontist. The correctors 102,202 may further be packaged with an assortment of third members 110 with a range of sizes to fit a variety of patients.
In alternative embodiments, the cantilever 106,206 is connected directly to a bonded appliance such as an upper buccal tube or auxiliary wire segment.
In further alternative embodiments, one or more of the orthodontic correctors above are adapted to correct a Class III malocclusion. Such correction may be achieved, for example, by connecting the one end of the assembly to the archwire 50 between the upper cuspid 12 and upper first bicuspid 14 and the other end of the assembly to the archwire 60 distal to the lower first buccal tube 42. Similar configurations for treating Class III malocclusions are described in issued U.S. Pat. No. 6,558,160 (Schnaitter et al.). As before, the connections between components benefit from the increased robustness and functionality provided by the present invention.
All of the patents and patent applications mentioned above are hereby expressly incorporated by reference. The embodiments described above are illustrative of the present invention and other constructions are also possible. Accordingly, the present invention should not be deemed limited to the embodiments described in detail above and shown in the accompanying drawings, but instead only by a fair scope of the claims that follow along with their equivalents.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US10/45102 | 8/11/2010 | WO | 00 | 1/16/2012 |
Number | Date | Country | |
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61235448 | Aug 2009 | US |