# Patent

## Title
Temporary anchorage device with external plate

## Abstract

A temporary anchor device includes at least one screw mechanism and an external plate. The at least one screw mechanism includes a skeletal screw having a threaded portion configured to drill into jaw bone of a patient, a smooth portion configured to sit within gums of the patient, and a proximal portion configured to extend external to the gums. The at least one screw mechanism further includes an attachment mechanism configured to attach to the proximal portion of the skeletal screw. The external plate is configured to be locked between the skeletal screw and the attachment mechanism to anchor the external plate external to the gums.

## Background
RELATED APPLICATIONS
This application claims priority to U.S. Patent Application No. 61/656,776, filed Jun. 7, 2012, and titled “TEMPORARY ANCHORAGE DEVICE WITH EXTERNAL PLATE,” the entirety of which is incorporated by reference herein.


INCORPORATION BY REFERENCE
All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.
BACKGROUND
In orthodontics, tooth movement generally requires placing force on the tooth, such as with braces. These forces require an anchoring point, such as a neighboring tooth. However, since the anchoring tooth is exposed to the same magnitude of reactive forces as the tooth or teeth being treated, the anchoring tooth often moves to an undesirable position. While these movements can be ignored for minor cases, in other cases, they can interfere with the orthodontic treatment. In extreme cases, the movements can require orthogenetic surgery, which has a relatively high morbidity rate, to replace the anchoring tooth.
To solve these problems, temporary anchorage devices (TADs) have been developed. These TADs are temporary implants that are placed in the jaw bone and can be connected an orthodontic device on the target tooth by springs or elastics. TADs can allow the target tooth to move in the desired direction while minimizing the effect on adjacent teeth.
Currently, there are two different designs for TADs. The first design is in the form of a single screw that is placed without surgery directly through the gum to the bone. However, this form of TAD, because it is a single screw, can be unstable and result in movement or dislodging of the screw during the anchoring process. Further, this type of screw mechanism traditionally has a screw thread extending the entire length of the device, which can both create irritation in the gums and provide a space for bacteria and other microorganisms to enter and cause infection.
The second TAD design includes an implantable surgical plate with multiple screws holding the external plate in place. This design must be implanted by a surgeon underneath the soft tissue such that the plate lies directly against the bone and is held in place with the screws. The surgical plate advantageously provides stability to the TAD. This design, however, requires the patient to undergo surgery, significant increasing the cost and risk associated with the design. Further, once implanted, the TAD cannot be adjusted or removed without further surgery. Moreover, if the external plate or the screws become loose over time, significant irritation can occur as a result of having the loose device in a closed space underneath the gums.
Accordingly, a TAD design that solves these problems is desired.
SUMMARY OF THE DISCLOSURE
The present invention relates generally to temporary anchorage devices.
In one embodiment, a temporary anchor device includes at least one screw mechanism and an external plate. The at least one screw mechanism includes a skeletal screw having a threaded portion configured to drill into jaw bone of a patient, a smooth portion configured to sit within gums of the patient, and a proximal portion configured to extend external to the gums. The at least one screw mechanism further includes an attachment mechanism configured to attach to the proximal portion of the skeletal screw. The external plate is configured to be locked between the skeletal screw and the attachment mechanism to anchor the external plate external to the gums.
In one embodiment, a method of anchoring an orthodontic device includes: screwing at least one skeletal screw through gums of a patient into jaw bone such that at least a proximal portion of the skeletal screw remains exposed external to the gums; placing an external plate on or around the proximal portion of the skeletal screw such that the external plate remains external to the gums; and attaching an attachment mechanism to the proximal end of the skeletal screw, thereby locking the external plate in place external to the gums.
These and other embodiments can include one or more of the following limitations.
The attachment mechanism can be configured to screw into the proximal portion of the skeletal screw.
There can be at least two skeletal screws. The external plate can include an elongate body having an elongate opening therein configured to fit the proximal portions of both screws therethrough.
The method can further include attaching an orthodontic device to the external plate.
The method can further include removing the attachment mechanism, removing the external plate, placing a second external plate on or around the proximal portion of the skeletal screw, and attaching the attachment mechanism to the proximal end of the screw, thereby locking the second external plate in place.
The external plate can include an orthodontic attachment feature configured to provide a point of attachment for an orthodontic device. The orthodontic device can include braces.
The smooth portion of the skeletal screw can be between 1-5 mm in length, such as approximately 3 mm. The helical portion can be between 2-10 mm in length, such as approximately 6 mm.
The method can further include placing the external plate such that it sits away from the gums, such as at least 0.5 mm, for example approximately 1 mm.
The orthodontic device can be placed near a posterior buccal plate of a maxillary or mandibular alveolar process. The orthodontic device can be placed such that it crosses a mid-palatal suture proximate to a first molar. The orthodontic device can be placed in an area of attached gingiva in an anterior buccal plate of a maxillary or mandibular alveolar process.



BRIEF DESCRIPTION OF THE DRAWINGS
The novel features of the invention are set forth with particularity in the claims that follow. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:
FIG. 1A is a front view of an exemplary temporary anchorage device as described herein. FIG. 1B is a back view of the exemplary temporary anchorage device of FIG. 1A.
FIG. 2A shows the skeletal screw of the device of FIG. 1. FIG. 2B shows the attachment mechanism of the device of FIG. 1. FIG. 2C shows the external plate of the device of FIG. 1.
FIG. 3A shows a sagittal view of a temporary anchorage device placed in the jaw as described herein. FIG. 3B shows a partially transparent frontal view of the temporary anchorage device placed in the jaw. FIG. 3C shows the interlocking features of the TAD device when in use.
FIG. 4A shows a sagittal view of an exemplary external plate. FIG. 4B shows a frontal view of the external plate of FIG. 4A.
FIG. 5A shows a sagittal view of another embodiment of an exemplary external plate. FIG. 5B shows a frontal view of the external plate of FIG. 5A.
FIG. 6A shows a sagittal view of another embodiment of an exemplary external plate. FIG. 6B shows a frontal view of the external plate of FIG. 6A.
FIG. 7A shows a sagittal view of another embodiment of an exemplary external plate. FIG. 7B shows a frontal view of the external plate of FIG. 7A.
FIG. 8A shows a sagittal view of another embodiment of an exemplary external plate. FIG. 8B shows a frontal view of the bite plate of FIG. 8A.



DETAILED DESCRIPTION
Referring to FIGS. 1A and 1B, a temporary anchorage device (TAD) 100 includes an external plate 101. The external plate 101 includes an elongate body 107 having at least one hole 105 therein. In some embodiments, as shown in FIGS. 1A-1B, the external plate 101 further includes an orthodontic attachment feature 109, such as a button, configured such that an orthodontic device, e.g., braces, can be connected thereto. For example, a wire, elastic, or spring of the orthodontic device can be connected to the attachment feature 109. The TAD 100 further includes at least one screw mechanism 103 attached to the external plate 101. Each screw mechanism 103 can extend through the hole 105 of the external plate 101 to provide an anchoring mechanism for the external plate 101. Further, as discussed further below, each screw mechanism 103 can include two separate parts—a skeletal screw 113 and an attachment mechanism 115.
The distinct parts of the TAD 100 are shown separately in FIGS. 2A-2C. As shown in FIG. 2A, the skeletal screw 113 includes a distal screw tip 204 having a helical thread 214 extending therearound. The skeletal screw 113 further includes a smooth middle portion 206, i.e. a portion without a thread. A proximal end 208 extends from the smooth middle portion 206. The proximal end 208 can have a diameter that is larger than the diameter of the middle portion 206. For example, the proximal end 208 can be bulbous or approximately spherical in shape. The proximal end 208 can further include a cut-out portion 218 configured to interlock with and/or hold the attachment mechanism 115 in place.
Referring to FIG. 2B, the attachment mechanism 115 can be configured to interlock with the proximal end 208 of the skeletal screw 113. For example, as shown in FIG. 2B, the attachment mechanism can include a screw-like portion 131 having threads 133 thereon configured to align with threads inside of the skeletal screw 113, such as inside the cut-out portion 218. Further, the attachment mechanism 115 can include a proximal end 135 configured to sit outside of the proximal end 135 of the skeletal screw 113 and hold the external plate 101 therebetween, as described further below.
As shown in FIG. 2C, the external plate 101 can include an elongate body 107 having at least one hole 105 therein. The hole 105 can run almost the entire length of the elongate body 107. By having an elongate body 107 and a hole 105 extending the length of the elongate body 107, the versatility of the TAD 100 and ease of implantation can be increased. Because the skeletal screw 113 of each screw mechanism 103 is implanted before the external plate 101, the elongated hole 105 can allow for simple placement of the external plate 101 over multiple skeletal screws 113. Accordingly, the elongated hole 105 allows for variation in the distance and angles between multiple skeletal screws 113. The elongate body 107 can further include sloped or beveled inner walls 202 leading from the front of the external plate 101 to the back of the external plate 101, i.e., the diameter db of the hole 105 at the back of the elongate body 107 can be smaller than the diameter df at the front of the elongate body 107. These sloped or beveled walls advantageously provide a ledge 254 or hook to lock the external plate 101 between the proximal end 208 (see FIG. 2A) of the skeletal screw 113 and the proximal end 135 (see FIG. 2B) of the attachment mechanism 115. That is, the proximal end 208 of the skeletal screw 113 and the proximal end 135 of the attachment mechanism 115 can both be too large to fit through the inner diameter of the hole 105, thereby forcing the two proximal ends 208, 135 to interact with the ledge 254.
As noted above, the external plate 101 can further include an orthodontic attachment feature 109 extending therefrom. For example, as shown in the FIG. 2C, the orthodontic attachment feature 109 can include an elongate extension portion 210 having a button 212 connected thereto. The button 212 can have an annular groove 219 therein configured to hold a wire or elastic of the orthodontic device. In some embodiments, the attachment feature 109 can be contiguous with and/or welded to the elongate body 107.
Referring to FIGS. 3A and 3B, the TAD 100 can be placed in the mouth of a patient such that the external plate 101 and at least a portion of the skeletal screw 113 and attachment mechanism 115 remain external to the gums 322 of a patient. In some embodiments, the orthodontic attachment feature 109 can extend towards the teeth 326 of the patient so as to provide a connection point for an orthodontic device. The TAD 100 can be placed, for example, into the posterior buccal plate of the maxillary and mandibular alveolar process or can be placed such that it crosses the mid-palatal suture in the area of the first molar. In other embodiments, such as for a TAD 100 having a relatively small external plate 101, the TAD 100 can be placed in the area of attached gingiva in the anterior buccal plate of maxillary and mandibular alveolar process. In some embodiments, the TAD 100 can be used without an external plate between the roots of any maxillary and mandibular teeth.
Referring to FIGS. 3B-3C, the TAD 100 can be placed by drilling the skeletal screw 113 into the jaws of the patient such that the screw tip 204 sits in the jaw bone 324 of the patient. Placing the screw tip 204 in the bone 342 of the patient advantageously provides a strong anchoring mechanism for the skeletal screw 113. Further, the skeletal screw 113 can be placed such that the smooth middle portion 206 sits within the gums 322 of the patient. The smooth middle portion 206 advantageously ensures that little irritation is caused to the gums 322 and/or reduces the probability of infection. The proximal end 208 of the skeletal screw 113 can sit external to the gums 322. The bulbous shape of the proximal end 208 can advantageously ensure that the proximal end of the skeletal screw 113 remains external to the gums 322. In some embodiments, one or more additional skeletal screws 113 are also placed through the gums 322 into the bone 324 of the patient.
Referring still to FIGS. 3B-3C, after the skeletal screw 113 has been set in place, the external plate 101 can be placed on or around the skeletal screw. For example, the external plate 101 can be placed such that at least a portion of the hole 105 extends over the proximal tip of the proximal end 208, i.e., through the diameter df (see FIG. 2C). However, the diameter db (see FIG. 2C) at the back of the elongate body 107 can prevent the proximal end 208 from extending all the way out through the hole 105 (see FIG. 1B). Accordingly, the proximal end 208 can sit against the inner side of the ledge 254 (see FIG. 2C) of the external plate 101. In some embodiments, if more than one skeletal screw 113 has been placed, the external plate 101 can be aligned such that it is placed on or around the additional skeletal screws as well.
Referring still to FIGS. 3B-3C, after the external plate 101 has been inserted over the skeletal screw or screws 113, the attachment mechanism 115 can be used to lock the external plate 101 in place. Thus, in one example, the screw portion 131 of the attachment mechanism 115 can be screwed into the skeletal screw 113, and the proximal end 135 of the attachment mechanism 115 can sit against the outer side of the ledge 254 (see FIG. 2C). That is, the diameter of the proximal end 135 can be such that it is too large to fit through the diameter df of the hole 105 (see FIG. 1B). If multiple skeletal screws 113 have been placed, then additional attachment mechanisms 115 can be placed accordingly. As a result, the external plate 101 can be locked into placed outside of the gums 322 of the patient. In some embodiments, the external plate 101 is held away from the gums of the patient to prevent irritation of the gums 322, such as with the proximal portion 208 of the skeletal screw 113. For example, the external plate 101 can sit at least 0.5 mm away from the gums 322, such as approximately 1 mm away from the gums. Keeping the external plate away from the gums reduces irritation and provides easy access for cleaning around the TAD 100.
The external plate 101 can advantageously be removed and replaced with a different external plate during use. That is, the attachment mechanism 115 can be removed, the external plate 101 removed, and then a new external plate locked into place with the attachment mechanism 115. By allowing the external plate 101 to be removable, the same screw mechanisms 103 can be used to support a variety of different external plates. Accordingly, the external plate can be changed, e.g., to switch to a different size or shape, easily without the need for surgery.
In some embodiments, a single screw mechanism 103 can be placed, used as a single attachment for a small external plate, and then additional screw mechanisms 103 can be placed at a later time for use with larger or different external plates. This step-by-step process can advantageously avoid unnecessary trauma in a single setting, particularly for small children.
Referring back to FIG. 3C, the dimensions of the screw mechanism 103 can be chosen so as to seat the screw mechanism 103 properly in the jaws and gums. For example, the length (ls) of the screw tip 204 can be between 2 mm and 10 mm, such as approximately 6 mm. This length can advantageously ensure that the screw tip 204 is well anchored while ensuring that as little damage as possible is done to the bone and that the screw mechanism 103 can be placed efficiently. Further, the length (lm) of the smooth middle portion 206 can be between 1 mm and 4 mm, such as approximately 3 mm. This length can correspond approximately to the width of the gums. Further, the proximal end 208 can have a length (lp) and/or width (wp) of 1-3 mm, such as approximately 2 mm. The width (wa) of the proximal end 135 of the attachment mechanism 115 can likewise be 1-3 mm, such as approximately 2 mm.
After the TAD device 100 has been placed in the patient, it can be used to anchor an orthodontic device. Accordingly, the TAD device 100 can be used, for example, for correction of severe open bite, retraction of anterior teeth, correction of mandibular prognatism, correction of maxillary prognatism, correction of severe anterior cross bite, intrusion of single or multiple teeth, correction of posterior cross bite, protraction of posterior teeth, and/or correction of deep bite.
Although the TAD 100 has been described as including a particular type of external plate 101, other variations are possible. For example, the walls 202 could be sloped in the opposite direction such that the diameter of the front of the hole 105 is larger than the diameter of the back of the hole 105. Further, the external plate need not be in the shape shown in FIGS. 1, 2, and 3, but could take other shapes. Likewise, the size and shape of the orthodontic attachment feature 109 could vary.
For example, referring to FIGS. 4A and 4B, the external plate 401 could have an elongate body 407 without an extending orthodontic attachment feature. The external plate 401 can be available in different sizes, ranging from 6 mm to 15 mm in length (l), such as approximately 8 mm, 10 mm, or 12 mm. The width (w) can be between 0.5 and 3 mm, such as approximately 1 mm. Further, the depth d can be between 1 mm and 5 mm, such as approximately 2 mm.
Referring to FIGS. 5A and 5B, the external plate 501 can include an elongate body 507, similar to the elongate body 407 described with respect to FIG. 4. However, the external plate 501 can further include an orthodontic attachment feature 509 extending from the elongate body 507. The orthodontic attachment feature 509 can include an elongate extension portion 510 and a molar tube 515 attached thereto. The molar tube 515 can be configured such that a wire can be passed therethrough. For example, the molar tube can be a rectangular tube, such as a standard edgewise tube without angulation. The elongate extension portion 410 can be curved such that the molar tube 515 is extends out and away from the elongate body 507 and/or the gums, as shown in FIG. 5B. Keeping the molar tube 515 away from the gums advantageously decreases irritation to the gums of the patient. Thus, the total width (w) of the external plate 501 can be between 1 mm and 5 mm, such as approximately 3 mm. Further, the extension portion 510 and the molar tube 515 can add between 1 mm and 10 mm to the depth (d), such as approximately 4 mm.
Referring to FIGS. 6A and 6B, the external plate 601 can be similar to the external plate 501 except that it can include a round button 517 in place of the molar tube 515. The round button can be used, for example, to connect spring or elastics from braces. For example, the button can include a groove and/or necked portion that allows a power chain or elastic to be connected thereto.
Further, the external plate need not include an elongate body at all, but could be relatively small and configured to attach to a single screw 103. For example, the external plate could be just small enough to fit a single screw mechanism therethrough, such as the round plate 701. The round plate 701 can advantageously increase the bulk of the head of the screw such that an elastic or wire can be attached behind the round plate 701. The round plate 701 can have a depth (d) and/or length (l) of 1-5 mm, such as approximately 3 mm and a width (w) of 0.5 to 3 mm such as approximately 1 mm.
Similarly, as shown in FIGS. 8A and 8B, the external plate 801 could be a small square device with a hole therethrough only large enough to fit a single screw mechanism and include an orthodontic attachment mechanism 809. The plate 801 can have a depth (d) of 1-6 mm, such as approximately 4 mm, a length (l) of 1-5 mm, such as approximately 3 mm, and a width (w) of 1-3 mm, such as approximately 2 mm.
Advantageously, the TAD described herein can be placed, removed, and adjusted without the need for a surgical procedure. Further, the TAD described herein can be advantageously stable due to the use of an external plate supported by multiple screws, i.e., having multiple screws can both divide the between the screws to avoid overloading a single screw and balance the moments across the various screws. Moreover, because no surgery is required, the TAD described herein is advantageously affordable for the patient and can be placed and in a short period of time, such as a few minutes, with very few side effects.

## Claims

1. A temporary anchorage device comprising:
at least one screw mechanism, the screw mechanism including:
a skeletal screw having a threaded portion configured to drill into jaw bone of a patient, a smooth portion having a length between 1-5 mm and configured to sit within gums of the patient, and a proximal portion configured to extend external to the gums;
an attachment mechanism configured to attach to the proximal portion of the skeletal screw; and
an external plate configured to be locked between the skeletal screw and the attachment mechanism to anchor the external plate external to the gums.

2. The temporary anchorage device of claim 1, wherein the attachment mechanism is a screw configured to screw into the proximal portion of the skeletal screw.

3. The temporary anchorage device of claim 1, wherein there are at least two skeletal screws.

4. The temporary anchorage device of claim 3, wherein the external plate comprises an elongate body having an elongate opening therein configured to fit the proximal portions of both screws therethrough, wherein the elongate body further comprises beveled inner walls leading from a front of the external plate to a back of the external plate.

5. The temporary anchorage device of claim 1, wherein the external plate comprises an orthodontic attachment feature configured to provide a point of attachment for an orthodontic device.

6. The temporary anchorage device of claim 5, wherein the orthodontic device comprises braces.

7. The temporary anchorage device of claim 1, wherein the smooth portion of the skeletal screw is approximately 3 mm in length.

8. The temporary anchorage device of claim 1, wherein the helical portion is between 2-10 mm in length.

9. The temporary anchorage device of claim 1, wherein the helical portion is approximately 6 mm in length.

10. A method of anchoring an orthodontic device comprising:
screwing at least one skeletal screw through gums of a patient into jaw bone such that at least a proximal portion of the skeletal screw remains exposed external to the gums and a smooth portion having a length of between 1-5 mm sits within the gums;
placing an external plate on or around the proximal portion of the skeletal screw such that the external plate remains external to the gums; and
attaching an attachment mechanism to the proximal end of the skeletal screw, thereby locking the external plate in place external to the gums.

11. The method of claim 10, further comprising attaching an orthodontic device to the external plate.

12. The method of claim 10, further comprising removing the attachment mechanism, removing the external plate, placing a second external plate on or around the proximal portion of the skeletal screw, and attaching the attachment mechanism to the proximal end of the screw, thereby locking the second external plate in place.

13. The method of claim 10, further comprising placing the external plate such that it sits a distance away from the gums.

14. The method of claim 13, wherein the distance is at least 0.5 mm.

15. The method of claim 13, wherein the distance is approximately 1 mm.

16. The method of claim 10, wherein the orthodontic device is placed near a posterior buccal plate of a maxillary or mandibular alveolar process.

17. The method of claim 10, wherein the orthodontic device is placed such that it crosses a mid-palatal suture proximate to a first molar.

18. The method of claim 10, wherein the orthodontic device is placed in an area of attached gingiva in an anterior buccal plate of a maxillary or mandibular alveolar process.