U.S. patent application number 12/759152 was filed with the patent office on 2010-08-05 for orthodontic systems with resilient appliances.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to Ming-Lai Lai, Tsi-Zong Tzou.
Application Number | 20100196840 12/759152 |
Document ID | / |
Family ID | 35636931 |
Filed Date | 2010-08-05 |
United States Patent
Application |
20100196840 |
Kind Code |
A1 |
Lai; Ming-Lai ; et
al. |
August 5, 2010 |
ORTHODONTIC SYSTEMS WITH RESILIENT APPLIANCES
Abstract
Systems for moving teeth of a patient's dental arch from a first
tooth arrangement to a second tooth arrangement include a plurality
of resilient appliances such as positioning trays or elongated arch
members that are used in sequence. Each appliance of the systems
includes a row of spaced apart couplings for connection to
respective teeth of the dental arch. The appliances have certain
geometric characteristics that match the geometric characteristics
of other appliances of the system, and at least one appliance has a
stiffness that is greater than the stiffness of at least one other
appliance.
Inventors: |
Lai; Ming-Lai; (Arcadia,
CA) ; Tzou; Tsi-Zong; (Arcadia, CA) |
Correspondence
Address: |
3M INNOVATIVE PROPERTIES COMPANY
PO BOX 33427
ST. PAUL
MN
55133-3427
US
|
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
35636931 |
Appl. No.: |
12/759152 |
Filed: |
April 13, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11766524 |
Jun 21, 2007 |
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12759152 |
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10983457 |
Nov 8, 2004 |
7234936 |
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11766524 |
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Current U.S.
Class: |
433/24 |
Current CPC
Class: |
A61C 7/08 20130101; A61C
7/30 20130101; A61C 7/20 20130101 |
Class at
Publication: |
433/24 |
International
Class: |
A61C 7/08 20060101
A61C007/08 |
Claims
1. A method for moving teeth of a patient's dental arch from a
first tooth arrangement to a second tooth arrangement comprising:
obtaining geometric information relating to one or more series of
resilient trays each having a buccolabial wall section, an occlusal
wall section and a lingual wall section, wherein each tray has a
row of receptacles for receiving respective teeth of the dental
arch of a dental patient, wherein each of the receptacles of each
tray is arranged in a certain relative orientation with respect to
the remaining receptacles of the same tray when the tray is
relaxed, wherein the relative orientation of the receptacles is
substantially the same for each of the trays, wherein at least one
of the trays has a stiffness that is greater than the stiffness of
at least one other tray, and wherein at least one of the
buccolabial, occlusal and lingual wall sections of at least one
tray is not in contact with a majority of the buccolabial, occlusal
and lingual sides respectively of the teeth of the dental patient
when received on the dental arch of the patient, with the proviso
that the plurality of resilient trays are not created using a model
of the dental patient's dentition; and using the geometric
information to select a pre-existing series from the one or more
series of resilient trays.
2. The method of claim 1, wherein the first tooth arrangement is a
tooth arrangement at the beginning of treatment or at an
intermediate stage of treatment.
3. The method of claim 1, wherein the second tooth arrangement is a
tooth arrangement at an intermediate stage of treatment or at the
conclusion of treatment.
4. The method of claim 1, wherein the stiffness of the trays is
varied at least in part by changing the thickness of said at least
one wall section of the buccolabial, occlusal and lingual wall
sections.
5. A method for moving teeth of a patient's dental arch from a
first tooth arrangement to a second tooth arrangement comprising:
obtaining geometric information relating to a plurality of
resilient trays each having a buccolabial wall section, an occlusal
wall section and a lingual wall section, wherein each tray has a
row of receptacles for receiving respective teeth of a dental arch
of a dental patient, wherein the row of receptacles of each tray
extends substantially along an arch-shaped curve that is
substantially the same for each of the trays when the trays are
relaxed, wherein at least one tray has a stiffness that is greater
than the stiffness of at least one other tray, and wherein at least
one of the buccolabial, occlusal and lingual wall sections of at
least one tray is not in contact with a majority of the
buccolabial, occlusal and lingual sides respectively of the teeth
of the dental patient when received on the dental arch of the
patient, with the proviso that the trays are not created using a
model of the dental patient's dentition; and using the geometric
information to select a pre-existing tray from the plurality of
resilient trays.
6. A method according to claim 5 wherein the first tooth
arrangement is a tooth arrangement at the beginning of treatment or
at an intermediate stage of treatment.
7. The method of claim 5, wherein the plurality of resilient trays
comprises at least three trays, wherein the first tooth arrangement
is a tooth arrangement at the beginning of treatment, and wherein
the second tooth arrangement is a tooth arrangement at an
intermediate stage of treatment or at the conclusion of
treatment.
8. The method of claim 5, wherein the curve is an embrasure
line.
9. The method of claim 5, wherein the plurality of resilient trays
includes at least three trays each having a stiffness that is
different from the stiffness of other trays of the system.
10. The method of claim 5, wherein the stiffness of the trays is
varied at least in part by changing the thickness of said at least
one wall section of the buccolabial, occlusal and lingual wall
sections.
11. A method for moving teeth of a patient's dental arch from an
initial tooth arrangement at the beginning of treatment to a final
tooth arrangement at the conclusion of treatment comprising:
obtaining geometric information relating to a plurality of
resilient trays including an initial tray for receiving the initial
tooth arrangement and a final tray for receiving the final tooth
arrangement, wherein each tray has a row of receptacles with a
buccolabial wall section and a lingual wall section for receiving
respective teeth of the dental arch, wherein the relative
orientation between the receptacles of the initial tray is
substantially the same as the relative orientation between the
receptacles of the final tray when the initial tray and the final
tray are relaxed, wherein at least one of the trays has a stiffness
that is greater than the stiffness of at least one other tray,
wherein at least some of the receptacles of the initial tray of the
system include an additional space adjacent at least one of its
buccolabial and lingual wall sections, and wherein the additional
space lacks an orthodontic appliance when the initial tray is
received on the dental arch, with the proviso that the plurality of
trays are not created using a model of the dental patient's
dentition; and using the geometric information to select a
pre-existing tray from the plurality of resilient trays.
12. The method of claim 11, wherein the row of receptacles of at
least one tray includes sufficient receptacles to receive all of
the teeth of the dental arch.
13. The method of claim 11, wherein the receptacles of at least one
tray have the same geometry as the geometry of the corresponding
receptacles of at least one other tray when the trays are
relaxed.
14. The method of claim 11, wherein the stiffness of the trays is
varied at least in part by changing the thickness of said at least
one wall section of the buccolabial and lingual wall sections.
15. A method for moving teeth of a patient's dental arch from an
initial tooth arrangement at the beginning of treatment to a final
tooth arrangement at the conclusion of treatment comprising:
obtaining geometric information relating to a plurality of
resilient trays including an initial tray for receiving the initial
tooth arrangement and a final tray for receiving the final tooth
arrangement, wherein each tray has a row of receptacles with a
buccolabial wall section and a lingual wall section for receiving
respective teeth of a dental arch, wherein the row of receptacles
of the initial tray and the row of receptacles of the final tray
extend substantially along the same arch-shaped curve when the
initial and final trays are relaxed, wherein the final tray has a
stiffness that is greater than the stiffness of the initial tray,
and wherein at least some of the receptacles of the initial tray of
the system include an additional space adjacent at least one of its
buccolabial and lingual wall sections, and wherein the additional
space lacks an orthodontic appliance when the initial tray is
received on the dental arch, with the proviso that the plurality of
resilient trays are not created using a model of the dental
patient's dentition; and using the geometric information to select
a pre-existing tray from the plurality of resilient trays.
16. The method of claim 15, wherein the receptacles of at least one
tray have the same geometry as the geometry of the corresponding
receptacles of at least one other tray when the trays are
relaxed.
17. The method of claim 15, wherein the curve is an embrasure
line.
18. The method of claim 15, wherein the plurality of resilient
trays includes at least three trays each having a stiffness that is
different from the stiffness of other trays of the system.
19. The method of claim 15, wherein the stiffness of the trays is
varied at least in part by changing the thickness of said at least
one wall section of the buccolabial and lingual wall sections.
Description
RELATED APPLICATION DATA
[0001] This application is a continuation of application Ser. No.
11/766,524, filed Jun. 21, 2007, which was a continuation of
application Ser. No. 10/983,457 (U.S. Pat. No. 7,234,936) now
issued.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to orthodontic treatment systems
wherein resilient appliances are used in sequence to move the
patient's teeth to desired orientations in the dental arch.
[0004] 2. Description of the Related Art
[0005] Orthodontic treatment involves movement of malpositioned
teeth to improved orientations. Orthodontic treatment can greatly
enhance the aesthetic appearance of the patient's teeth, especially
in regions near the front of the oral cavity. Orthodontic treatment
can also improve the patient's occlusion so that the teeth function
better with each other during mastication.
[0006] One type of orthodontic treatment is carried out by the use
of elastomeric positioning appliances, also known as repositioning
trays or alignment trays. These appliances have overall, generally
"U"-shaped configuration that generally matches the shape of the
patient's dental arch, and a row of receptacles in the appliance
receive respective teeth of the dental arch. Some patients favor
elastomeric positioning appliances because they can be removed
while eating.
[0007] Elastomeric positioning appliances are often made by first
taking an impression of the patient's dental arches and then making
a plaster of Paris or "stone" model from the impression. Next, the
teeth of the stone model representing the teeth to be moved during
treatment are cut or sawn from remaining portions of the model and
repositioned as desired, using a wax or other material to hold the
repositioned teeth in place. A sheet of thermoplastic material is
then placed over the model and heated such that the sheet is formed
into the exact shape of the model with the repositioned teeth.
Subsequently, edges of the sheet are trimmed as desired to form a
tray. When the tray is set in place over the patient's dental arch,
the elastic characteristics of the thermoplastic material tend to
move the teeth toward the orientations as represented by the
repositioned teeth of the model.
[0008] A system of elastomeric positioning appliances available
from Align Technology, Inc. of Santa Clara, Calif. involves a
series of alignment trays that are used in sequence. The trays are
custom-made for each patient, and each tray is constructed to move
the teeth along an incremental portion of the treatment path. One
possible method of making such positioning trays is somewhat
similar to the method described above, except that a model is
provided for each tray of the series and the teeth are repositioned
on each model in accordance with the intended incremental positions
of the patient's teeth along the desired treatment path.
[0009] Another type of orthodontic treatment is carried out by the
use of a series of tiny, slotted brackets, each of which is affixed
to a respective tooth of the patient's dental arch. A resilient
arch member such as a curved, elongated archwire is placed in the
slot of each bracket. Ends of the archwire are often received in
devices known as buccal tubes that are affixed to the patient's
molar teeth. The archwire serves as a track to guide movement of
the teeth to desired positions.
SUMMARY OF THE INVENTION
[0010] The present invention is directed to novel systems of
orthodontic appliances that include a series of resilient
appliances for use in sequence. Each appliance of the series is
constructed to move the teeth toward desired positions and may
optionally have a geometry identical to the geometry of other
appliances of the system. However, at least one of the appliances
is constructed to provide a greater amount of force per unit
displacement of tooth movement on at least some of the teeth than
other appliances of the series in order to more efficiently move
the teeth to their final positions as the end of the treatment
program is approached.
[0011] In more detail, the present invention in one aspect is
directed toward a system for moving teeth of a patient's dental
arch from a first tooth arrangement to a second tooth arrangement.
The system comprises a plurality of resilient trays each having a
buccolabial wall section, an occlusal wall section and a lingual
wall section. Each tray has a row of receptacles for receiving
respective teeth of the dental arch of a dental patient, and each
of the receptacles of each tray is arranged in a certain relative
orientation with respect to the remaining receptacles of the same
tray when the tray is relaxed. The relative orientation of the
receptacles is substantially the same for each of the trays, and at
least one of the trays has a stiffness that is greater than the
stiffness of at least one other tray. At least one of the
buccolabial, occlusal and lingual wall sections of at least one
tray is not in contact with a majority of the buccolabial, occlusal
and lingual sides respectively of the teeth of the dental patient
when received on the dental arch of the patient.
[0012] Another aspect of the present invention is also directed to
a system for moving teeth of a patient's dental arch from a first
tooth arrangement to a second tooth arrangement. This system
comprises a plurality of resilient trays each having a buccolabial
wall section, an occlusal wall section and a lingual wall section.
Each tray has a row of receptacles for receiving respective teeth
of a dental arch of a dental patient, and the row of receptacles of
each tray extends substantially along an arch-shaped curve that is
substantially the same for each of the trays when the trays are
relaxed. At least one tray has a stiffness that is greater than the
stiffness of at least one other tray, and at least one of the
buccolabial, occlusal and lingual wall sections of at least one
tray is not in contact with a majority of the buccolabial, occlusal
and lingual sides respectively of the teeth of the dental patient
when received on the dental arch of the patient.
[0013] The present invention is also directed in another aspect
toward a system for moving teeth of a patient's dental arch from an
initial tooth arrangement at the beginning of treatment to a final
tooth arrangement at the conclusion of treatment. The system
comprises a plurality of resilient trays including an initial tray
for receiving the initial tooth arrangement and a final tray for
receiving the final tooth arrangement. Each tray has a row of
receptacles with a buccolabial wall section and a lingual wall
section for receiving respective teeth of the dental arch, and the
relative orientation between the receptacles of the initial tray is
substantially the same as the relative orientation between the
receptacles of the final tray when the initial tray and the final
tray are relaxed. At least one of the trays has a stiffness that is
greater than the stiffness of at least one other tray.
Additionally, at least some of the receptacles of the initial tray
of the system includes an additional space adjacent at least one of
its buccolabial and lingual wall sections, and the additional space
lacks an orthodontic appliance when the initial tray is received on
the dental arch.
[0014] The present invention in another aspect is also directed
toward a system for moving teeth of a patient's dental arch from an
initial tooth arrangement at the beginning of treatment to a final
tooth arrangement at the conclusion of treatment. The system
comprises a plurality of resilient trays including an initial tray
for receiving the initial tooth arrangement and a final tray for
receiving the final tooth arrangement. Each tray has a row of
receptacles with a buccolabial wall section and a lingual wall
section for receiving respective teeth of a dental arch, and the
row of receptacles of the initial tray and the row of receptacles
of the final tray extend along substantially along the same
arch-shaped curve when the initial and final trays are relaxed. The
final tray has a stiffness that is greater than the stiffness of
the initial tray. At least some of the receptacles of the initial
tray of the system include an additional space adjacent at least
one of its buccolabial and lingual wall sections, and the
additional space lacks an orthodontic appliance when the initial
tray is received on the dental arch.
[0015] Optionally, all of the appliances (such as the trays) can be
constructed using standardized or ideal arch forms. Moreover, the
couplings of the appliances (such as the tooth receptacles of the
trays) may have a configuration adapted to receive teeth within a
selected range of sizes. Accordingly, the time and expense of
designing and constructing custom-made appliances for each patient
can be avoided.
[0016] These and other features of the invention are described in
more detail in the paragraphs that follow and are illustrated in
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is an inverted perspective view of one resilient
appliance of an orthodontic system according to one embodiment of
the present invention;
[0018] FIG. 2 is a side elevational view of the appliance and the
dental arch shown in FIG. 1 illustrating the appliance in place
over an exemplary dental arch of an orthodontic patient;
[0019] FIG. 3 is a bottom view of the appliance and the dental arch
illustrated in FIG. 2;
[0020] FIG. 4 is a bottom view of an exemplary ideal dental
archform, illustrating the location of an embrasure line;
[0021] FIG. 5 is a perspective view of one resilient appliance of
an orthodontic system according to another embodiment of the
invention;
[0022] FIG. 6 is a view somewhat similar to FIG. 3 except showing
one resilient appliance of an orthodontic system according to yet
another embodiment of the invention;
[0023] FIG. 7 is a front elevational view of one resilient
appliance of an orthodontic system according to still another
embodiment of the invention, showing the appliance coupled to a row
of connector members that are affixed to respective teeth of an
exemplary dental arch of an orthodontic patient;
[0024] FIG. 8 is a view somewhat similar to FIG. 7 except that the
appliance has been removed;
[0025] FIG. 9 is an enlarged side elevational view of one of the
connector members alone that is shown in FIGS. 7 and 8;
[0026] FIG. 10 is an enlarged side cross-sectional view of the
appliance and one of the connector members depicted in FIG. 7,
along with the adjacent tooth;
[0027] FIG. 11 is a front elevational view of one resilient
appliance of an orthodontic system according to yet another
embodiment of the invention, illustrating the appliance connected
to a row of brackets that are affixed to teeth of an exemplary
dental arch of an orthodontic patient;
[0028] FIG. 12 is a perspective view of the appliance alone that is
shown in FIG. 11; and
[0029] FIG. 13 is an enlarged, fragmentary, front elevational view
of a portion of the resilient appliance along with two of the
brackets that are illustrated in FIG. 11.
DEFINITIONS
[0030] "Mesial" means in a direction toward the center of the
patient's curved dental arch.
[0031] "Distal" means in a direction away from the center of the
patient's curved dental arch.
[0032] "Occlusal" means in a direction toward the outer tips of the
patient's teeth.
[0033] "Gingival" means in a direction toward the patient's gums or
gingiva.
[0034] "Buccolabial" means in a direction toward the patient's
cheeks or lips.
[0035] "Lingual" means in a direction toward the patient's
tongue.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] A system for moving teeth of a patient's dental arch from a
first tooth arrangement to a second tooth arrangement comprises a
plurality of resilient appliances that are used in sequence. In the
embodiment illustrated in FIGS. 1-3, the appliances comprise trays,
and an exemplary tray of the system is broadly designated by the
numeral 10. In FIGS. 2 and 3, the tray 10 is shown in use, placed
over an exemplary dental arch 12 of an orthodontic patient. The
tray 10 is shown alone in FIG. 1.
[0037] The tray 10 includes a row of spaced apart couplings or
receptacles 14 (see FIG. 3), each of which is adapted to connect to
and receive a respective tooth 16 of the patient's dental arch. The
receptacles 14 are spaced apart from each other along the length of
the tray 10, although adjoining regions of adjacent receptacles 14
are in communication with each other.
[0038] Each of the receptacles 14 includes at least one wall
section 18 that is constructed to urge the respective tooth toward
a desired orientation. In this embodiment, the wall sections 18
include a buccolabial wall section that extends across and contacts
a buccolabial side of the tooth 16, a lingual wall section that
extends across and contacts a lingual side of the tooth 16 and an
occlusal wall section that extends across and contacts an occlusal
portion of the tooth 16, preferably including the outermost
occlusal edge of the tooth 16.
[0039] In the embodiment of FIGS. 1-3, the inner surfaces of the
buccolabial wall section, the lingual wall section and the occlusal
wall sections matingly contact and are closely identical in shape
to the buccolabial side, the lingual side and the occlusal portion
respectively of the teeth 16. The gaps between the wall sections
and the adjacent sides of the teeth are shown in FIG. 3 only for
purposes of illustration, and preferably are avoided so that the
wall sections 18 are in close, complemental contact with the
external tooth surfaces.
[0040] Each of the receptacles 14 for at least two of the trays of
the series, more preferably for at least three trays of the series,
and most preferably for all of the trays of the series is
positioned in a desired orientation that matches the desired final
orientation of the respective tooth at the conclusion of treatment.
For example, in designing the tray 10, each tooth 16 has six
degrees of freedom of movement. First, each tooth will have a
desired angulation at the conclusion of treatment. Angulation may
be defined according to the teachings of Dr. Lawrence A. Andrews as
the mesiodistal cant of the facial axis of the clinical crown
("FACC") relative to a line perpendicular to the occlusal plane
(see, e.g., Straight Wire, The Concept and Appliance, by Lawrence
F. Andrews (L.A. Wells Co., copyright 1989)). Second, each tooth
will also have a desired torque at the conclusion of treatment, and
torque may be defined as the buccolabial-lingual cant of the FACC
when measured from a line perpendicular to the occlusal plane.
Third, each tooth 16 will have a desired rotation at the conclusion
of treatment, and rotation can be defined as the rotational
position of the tooth 16 in an arc about its long axis. Finally,
each tooth 16 may be moved in translation in directions along three
reference axes: a mesial-distal reference axis, a
buccolabial-lingual reference axis, and an occlusal-gingival
reference axis.
[0041] Optionally, the angulation, torque and crown prominence
(i.e. the distance in a buccolabial direction from the embrasure
line to each crown's most prominent facial point) of the teeth are
identical to the known preferred values. Examples of suitable
preferred values include those values associated with the treatment
philosophies of Dr. Andrews or of Drs. McLaughlin, Bennett and
Trevisi (such as embodied in the "MBT" brand brackets and buccal
tubes from 3M Unitek Corporation) as set out in Tables I and II
below. Additional information regarding the treatment philosophies
of Drs. McLaughlin, Bennett and Trevisi is set out in their book
entitled "Systemized Orthodontic Treatment Mechanics" (Mosby,
2001).
TABLE-US-00001 TABLE I Maxillary Arch 1.sup.st 2.sup.nd 1.sup.st
2.sup.nd Central Lateral Cuspid Bicuspid Bicuspid Molar Molar
Andrews 2.1 1.65 2.5 2.4 2.5 2.9 2.9 Crown Prominence, mm Andrews 7
3 -7 -7 -7 -9 -9 torque, degrees Andrews 5 9 11 2 2 5 5 angulation,
degrees MBT 17 10 -7, +7 -7 -7 -14 -14 torque, or 0 degrees MBT 4 8
8 0 0 0 0 angulation, degrees
TABLE-US-00002 TABLE II Mandibular Arch 1.sup.st 2.sup.nd 1.sup.st
2.sup.nd Central Lateral Cuspid Bicuspid Bicuspid Molar Molar
Andrews 1.2 1.2 1.9 2.35 2.35 2.5 2.5 Crown Prominence, mm Andrews
-1 -1 -11 -17 -22 -30 -35 torque, degrees Andrews 2 2 5 2 2 2 2
angulation, degrees MBT -6 -6 -6, +6 -12 -17 -20 -10 torque, or 0
degrees MBT 0 0 3 2 2 0 0 angulation, degrees
[0042] When the tray 10 is relaxed, the geometric orientation of
each of the receptacles 14 matches the desired orientation of the
respective tooth 16 at the conclusion of treatment. As a
consequence, each of the receptacles 14 when the tray 10 is relaxed
has a geometry sufficient to hold the respective tooth 16 in its
desired final orientation with desired angulation, torque,
rotation, and translation values, assuming that the tooth is free
to move in space and is not constrained by other factors such as
restraints imposed by the periodontal ligament and/or alveolar
bone.
[0043] Optionally, the receptacle 14 does not have a shape that
entirely matches the shape of the exposed portions of the tooth 16.
For example, the wall sections 18 may be complemental to and
contact the buccolabial and lingual sides of the tooth 16, but may
not include an occlusal section in contact with the occlusal edge
of the tooth 16. As another option, the wall sections 18 may
include an occlusal wall section for contact with the occlusal
portion of the patient's tooth, but lack a buccolabial or a lingual
wall section that is in contact with a majority of the buccolabial
or lingual sides of the tooth 16. However, the wall sections 18
have sufficient area in contact with the tooth 16 to urge the tooth
16 toward its desired orientation.
[0044] Preferably, the receptacles 14 are arranged along a row when
the tray 10 is relaxed that extends along a predefined arch-shaped
reference curve such as an ideal embrasure line. An example of an
embrasure line is designated by the letter "e" in FIG. 4 for the
exemplary dental arch 12. The embrasure line is an imaginary curve,
located at the level of the tooth crown's midtransverse plane that
connects the most facial portions of the contact areas of all of
the tooth crowns in the arch 12 when the teeth 16 are in desired
orientations. A variety of embrasure lines are possible, including
embrasure lines that extend along paths offset and parallel to the
shapes of commonly available orthodontic archwires. Examples of
suitable archwire shapes include the shapes of "OrthoForm I
Tapered" brand archwires, "OrthoForm II Square" brand archwires and
"OrthoForm III Ovoid" brand archwires from 3M Unitek Corporation.
The receptacles are deemed to extend along the embrasure line when
a negative image of the receptacles appears as an image of the
teeth when in desired orientations along the embrasure line.
[0045] In the embodiment illustrated in FIGS. 1-3, the outer wall
surfaces of the tray 10 including the outer surfaces of its
buccolabial, occlusal and lingual wall sections are somewhat
similar in shape to the underlying buccolabial, occlusal and
lingual surfaces of the dental arch 12. This construction is an
advantage, in that the volume occupied by the tray 10 in the oral
cavity is reduced. However, other constructions are also possible.
For example, the outer surfaces of the buccolabial and lingual wall
sections 18 could extend along respective curves that follow in
parallel to the embrasure line and lack recessed areas
corresponding to the underlying interproximal regions of the dental
arch 12.
[0046] In accordance with the present invention, a system for
moving teeth of a patient's dental arch from a first tooth
arrangement to a second tooth arrangement comprises two or more
resilient appliances, and preferably at least three resilient
appliances, such as the trays 10. The trays 10 are used in a
pre-determined sequence in accordance with the progress of movement
of the teeth from the first tooth arrangement to the second tooth
arrangement.
[0047] Each tooth arrangement is an arrangement of the teeth at
some point in time during the course of treatment. As described
herein, for example, the first and second arrangements could be the
initial and final arrangements respectively. Alternatively, the
first and second arrangements could be the initial and next
subsequent arrangements respectively, or the next-to-final and
final arrangements respectively. As another alternative, the first
and second arrangements could both be arrangements at intermediate
points during the course of treatment.
[0048] In one embodiment of the invention, at least two trays of
the series, more preferably at least three trays of the series and
most preferably all of the trays of the series are identical in
appearance when relaxed. Consequently, in this embodiment, the row
of receptacles of each tray when the tray is relaxed extends along
the same embrasure line, such as the embrasure line "e" that is
depicted in FIG. 4.
[0049] Furthermore, the relative orientation of the receptacles
with respect to the remaining receptacles of the same tray when the
tray is relaxed is substantially the same for each of the trays,
and is preferably identical for each of the trays. For example, the
orientation of a receptacle may be determined by reference to a
hypothetical axis that is collinear with the FACC of the tooth when
the tooth is received in the receptacle. In this example, for
instance, the spacing and angular orientation between this
hypothetical axis of the receptacle for the upper right lateral
tooth and the hypothetical axis of the receptacle for the upper
right cuspid tooth are the same for each tray of the system when
the trays are relaxed. Similarly, the spacing and angular
orientation between other receptacles are the same for each tray of
the system when the trays are relaxed.
[0050] However, at least one of the trays of the series and
preferably at least two trays of the series are constructed to
provide a greater force against at least some of the teeth for a
given dental arch relative to the force provided against the same
teeth by at least one other tray of the system. For example, at
least one tray has a stiffness that is greater than the stiffness
of at least one other tray. The stiffness may be varied among the
trays by altering the composition or processing conditions of the
material used to make the trays, by changing the construction of
the trays (for example, by changing the thickness of the wall
sections 18 in a buccolabial-lingual direction), or by other
methods. The stiffness may be determined by any suitable method,
such as the tensile strength test that is set out in ASTM Test
Method D412 for elastomeric materials or the tensile strength test
that is set out in ASTM Test Method D882 for plastic materials.
[0051] Preferably, each tray of the series has a different
stiffness, and the trays are selected so that the stiffness
increases as treatment progresses. For example, the series may
include at least three trays, each having a greater stiffness than
the previous tray when used in the proper sequence. In this manner,
the trays used in the earlier stages of treatment, such as the
initial tray, provide a relatively light force per unit
displacement on the teeth.
[0052] As treatment progresses and as the teeth are moved closer to
a desired tooth arrangement, stiffer trays are utilized. The
increased stiffness of subsequent trays of the system provides
additional force on the teeth to help ensure that the teeth are
moved to their final desired positions, even though the amount of
remaining necessary tooth movement is relatively small. The
increased stiffness also helps to stabilize the teeth and hold the
teeth firmly in place without undue movement while the teeth are in
or near desired final positions. Additionally, the increased
stiffness of subsequent trays of the system helps ensure that there
is sufficient force to overcome the minimum, threshold force
necessary to continue movement of the teeth to final positions.
[0053] Optionally, all of the trays of the series are made in
advance by a manufacturer according to a set of statistical
averages or norms. For example, data could be gathered from a
number of individuals regarding the size of each tooth, including
the thickness of the tooth in a buccolabial-lingual direction, the
height of a tooth in an occlusal-gingival direction and the width
of a tooth in a mesial-distal direction. Optionally, the thickness
of the tooth is the greatest buccolabial-lingual thickness taken in
a reference plane that passes through the facial axis point. The
height of the tooth, or cusp height, is measured from the cusp tip
to the depth of the central sulcus midway mesiodistally. The width
of the tooth is determined by measuring the greatest mesiodistal
diameter of the tooth.
[0054] Next, a number of possible size ranges is developed using
statistical analysis in order to determine the optimal
configuration of each of the receptacles for the trays of each
series. For example, five series of trays can be developed
corresponding to five different ranges of overall arch length as
determined along a curved mesial-distal reference axis. Each series
includes trays with receptacles adapted to fit a range of sizes so
that, in all likelihood, one tray series and possibly two will
include trays having receptacles adapted to receive the teeth of
any particular patient with a relatively close mating fit.
[0055] For instance, the gathered tooth data could be analyzed for
each tooth such that the mean tooth height and mean tooth thickness
are derived for receptacles adapted to fit a certain range of tooth
widths. The dimensions of the receptacles that correspond to the
tooth heights and tooth thicknesses are then selected to receive
the respective teeth in relatively close complemental relationship
for each chosen range of tooth widths. The analysis is repeated for
each receptacle of each series. Generally speaking, the mean tooth
height and mean tooth thickness are known to increase and decrease
in proportion to the increase and decrease in tooth width.
Consequently, the practitioner can select the proper series for a
best fit from a choice of different, pre-manufactured series based
only on a determination of the tooth widths of some or all of the
teeth of the patient in need of treatment.
[0056] The manufacture and supply of two or more series of trays in
advance of knowing individual patient data (such as the patient's
tooth sizes or type of malocclusion) is a significant advantage, in
that the manufacturer and/or practitioner can maintain an inventory
of trays in advance. Once the practitioner has selected a series of
trays that best fit the patient at hand, the first tray of the
series can be retrieved from inventory for the prompt initiation of
treatment. Moreover, the need to make additional trays once
treatment is underway can be avoided, such as in instances in the
past where custom-made trays have not moved the teeth as intended
and a mid-course correction with another custom tray is needed.
[0057] Selection of the proper series of trays for any particular
patient can be carried out by any one of a number of methods. For
example, the practitioner may use manual methods such as calipers
to determine the height, width and/or thickness of each tooth. The
practitioner can then consult manufacturer's data regarding the
various available series of trays, so that the series providing the
best fit can be chosen.
[0058] Alternatively, the practitioner may obtain a digital data
file regarding the tooth shapes of the patient. The data file may
be obtained by an intra-oral scanner, or by a scanner that scans
either an impression of the patient's teeth or a model of the
patient's teeth. The data file may include data regarding the
height, width, thickness, or volume of each tooth, or any
combination of the foregoing. Optionally, this data file may also
include information regarding the shape and/or orientation of each
tooth. Computer software can then be employed to analyze the data
and select a particular series of trays from a number of different
series.
[0059] For example, the software can select the best series by
analyzing the data regarding tooth widths, and then selecting the
series by comparing the widths of the receptacles of various series
to the corresponding widths of the teeth. As another example, the
software can select the best series by first determining the
desired tooth positions at the conclusion of treatment, and then
fitting a hypothetical curve to the embrasure line of the teeth at
the conclusion of treatment. This embrasure line is then compared
to the arch-shaped curve along which the receptacles of the various
series extend, in order to select the series that presents a curve
that most closely matches the desired embrasure line at the
conclusion of treatment. Optionally, the embrasure line used by the
software for purposes of comparison may extend along all of the
teeth of the patient's dental arch, or along only a portion of the
patient's dental arch.
[0060] Optionally, the manufacturer may assist the practitioner in
the selection of the best series of trays. For instance, the
practitioner may transmit the tooth data to the manufacturer via
the Internet so that the manufacturer can use the software
mentioned above and, with the practitioner's approval, promptly
ship the selected series to the practitioner, preferably from an
inventory of previously manufactured trays. As another alternative,
the practitioner can use the software mentioned above in the
practitioner's office or via an interactive program connected by
the Internet to the manufacturer's facilities, and pick the best
series from an inventory maintained in the practitioner's
office.
[0061] Optionally, the height of one or more of the receptacles in
an occlusal-gingival direction may be greater than needed to
receive the patient's tooth at the beginning of use of the tray.
Such construction facilitates the continued eruption of teeth that
have only partially erupted and helps ensure that the tray does not
hinder the tooth in reaching its full desired height at maturity.
In this example, data for a particular patient regarding the height
of some of the patient's teeth may be ignored for the purpose of
selecting the best series of trays.
[0062] As an additional option, the first tray of the series may
have receptacles with additional space adjacent its buccolabial
wall section or lingual wall section. This additional space is an
advantage in instances where the patient's teeth are significantly
crowded at the beginning of treatment.
[0063] Preferably, the trays including the tray 10 are comprised of
an aesthetically pleasing material that is resistant to staining by
food and beverages. Preferably, the material is colorless, and
preferably transmits light in the visible wavelengths. Preferably,
the material transmits sufficient light so that the natural color
of the patient's tooth can be observed through the tray.
[0064] The trays are preferably made of resilient polymeric
materials such as polyurethane, silicone, latex, fluoropolymer and
polyolefin. Examples of suitable polyurethane materials include
polyester-based materials (such as Texin 285 brand, Texin 390 brand
and Desmopan 453 materials, all from Bayer). Other suitable
polyurethane materials include Pellethane brand polytetramethylene
glycol ether nos. 2363-80A, 2363-55D and 2363-62D, all from Dow
Chemical. Other suitable polyurethane materials include Tecoflex
brand polyether-based material, nos. 80A, 60D and 72D, all from
Themedics.
[0065] Suitable silicone materials for the tray include RD 10333
brand silicone from RD Rubber, MED-4725 and MED-4755 brand silicone
from NuSil, no. 50069 silicone from Rhodia Silicones, LIM6071
silicone from General Electric and Baysilone brand silicone, no.
LSR 2670 from Bayer. Suitable rubber materials include K-100
natural rubber and K-3800 thermoplastic rubber from Kent Elastomer.
Suitable fluoropolymer materials include no. FC 2145
fluoroelastomer from 3M Dyneon.
[0066] The trays may comprise a viscoelastic material. As an
option, the viscoelastic material can be manually deformed to a
permanent or semipermanent change in configuration by the
practitioner so that, for example, a particular receptacle can be
extended in a direction to better accommodate a severely
malpositioned tooth. Preferably, the viscoelastic material has
sufficient inherent memory to urge the receptacle back toward its
original position over a period of time. Preferably, the
viscoelastic material exhibits a tan .delta. in the range of about
0.01 to about 2.0, where tan .delta. is defined as the ratio of the
shear loss modulus (G'') to the shear storage modulus (G') as
described, for example, in Viscoelastic Properties of Polymers, by
John D. Ferry (third edition, John Wiley and Sons, Inc., copyright
1980).
[0067] Optionally, the series of appliances may include other
appliances as well. For example, the series may include two or more
identical trays with the same stiffness. Identical trays may be
desired in instances where the tray is replaced with an identical
tray after a length of time, such as in instances where the tray is
subject to undue wear or in instances where the stiffness of the
tray significantly changes over a period of time. The series of
appliances may also include other types of appliances, such as a
brace comprising brackets and an archwire for use in the final
stage of treatment and after use of the trays has been
concluded.
[0068] A system for moving teeth of a patient's dental arch
according to another embodiment of the invention also comprises a
series of trays, one of which is designated by the numeral 10a in
FIG. 5. The tray 10a includes a row of spaced apart couplings or
receptacles 14a, each of which is adapted to receive and connect to
a respective tooth of a patient's dental arch.
[0069] The tray 10a is somewhat similar to the tray 10, except that
the tray 10a has wall sections 18a that present a smoothly curved
buccolabial surface and a smoothly curved lingual surface. The
buccolabial and lingual surfaces in this embodiment extend in
parallel relationship to an embrasure line (not shown in FIG. 5).
Such construction provides regions of increased wall section
thickness, particularly in regions adjacent the underlying
interproximal areas of the patient's dental arch. In other aspects,
the tray 10a is essentially the same as the tray 10 described
above.
[0070] A system for moving teeth of a patient's dental arch
according to another embodiment of the invention comprises a series
of trays that is exemplified by the tray 10b shown in FIG. 6. The
tray 10b includes a shell-like frame 11b having an overall,
generally "U"-shaped configuration that is adapted to fit over the
dental arch of an orthodontic patient. The frame 11b also has a
generally "U"-shaped configuration in cross-sections taken in
reference planes perpendicular to the curved central axis of the
frame 11b.
[0071] The tray 10b includes a series of spaced apart wall sections
18b that are fixed to the frame 11b. Some of the wall sections 18b
extend in a lingual direction from the buccolabial side of the
frame 11b, while the remaining wall sections 18b extend in a
buccolabial direction from the lingual side of the frame 11b. Each
pair of opposed wall sections 18b partially defines a receptacle
14b for receiving a tooth 16b of a dental arch 12b.
[0072] Optionally, the protruding wall sections 18b are made of a
material that is different from the material of the frame 11b. For
example, the wall sections 18b may be made of a material that has
less stiffness or greater stiffness than the stiffness of the
material of the frame 11b. The wall sections 18b may also be
provided with surface structure such as a roughened surface that
facilitates firm, essentially non-sliding contact between the wall
sections 18b and the engaged surfaces of the tooth 16b.
[0073] Preferably, the frame 11b is made of a material that deforms
when the tray 10b is placed over the maloccluded teeth. The
inherent resiliency of the frame 11b then tends to move the teeth
toward desired positions. When the tray 10 is relaxed, the
buccolabial and lingual sides of frame 11b preferably follow in
parallel along respective curves that are parallel to the desired
reference curve such as the embrasure line. As such, the
configuration of the frame 11b when the tray is relaxed will match
the configuration of the frame 11a once the teeth of the dental
arch 12b have moved to their desired positions.
[0074] Except as described above, the series of trays that includes
the tray 10b is essentially the same as the series of trays that
includes the tray 10 set out above. For example, in one embodiment
at least one tray of the series of trays that includes the tray 10b
that is having a stiffness that is greater than the stiffness of at
least one other tray of the same series. The variation in stiffness
may be carried out by modifying that material of the wall sections
18b, by modifying the material of the frame 11b, by varying the
thickness of the wall sections 18b and/or of the frame 11b, or by
any combination of the foregoing. Moreover, at least two trays of
the series that includes the tray 10b includes a row of the
receptacles that extends along substantially the same arch-shaped
reference curve such as the embrasure line, and the receptacles are
arranged in a certain relative orientation with respect to
remaining receptacles of the same tray when the tray is
relaxed.
[0075] A system for moving teeth of a patient's dental arch from a
first tooth arrangement to a second tooth arrangement according to
another embodiment of the invention is depicted in FIGS. 7-10 and
comprises a plurality of resilient appliances or arch members 22
used in sequence. An exemplary arch member 22 is shown in FIGS. 7
and 10. The arch member 22 along with a series of connector members
24 together comprise an orthodontic brace that is broadly
designated by the numeral 20.
[0076] Each of the connector members 24 is affixed to a respective
tooth 26 of a patient's dental arch 28. In FIGS. 7, 8 and 10, the
illustrated dental arch 28 is an exemplary maxillary or upper
dental arch, although it should be understood in this regard that
the brace 20 may be adapted for use with the mandibular or lower
dental arch as well.
[0077] FIG. 8 is an illustration somewhat similar to FIG. 7, except
that the arch member 22 has been removed. As shown, the connector
members 24 are directly bonded to the enamel surface of the
patient's teeth 26. Preferably, each tooth 26 of the dental arch 28
receives a connector member 24, although alternative arrangements
are also possible. For example, the connector members 24 may be
attached to all of the teeth 26 in the dental arch 28 except for
the molar teeth, or may be attached to only certain selected teeth
as may be desired by the practitioner.
[0078] FIG. 9 is a side elevational view of the connector member 24
alone. The connector member 24 includes a base 30 having an
external surface that is adapted to be directly bonded to the
enamel surface of the patient's tooth 26 by an adhesive.
Optionally, the external surface of the base 30 has a compound
concave contour that precisely matches the convex compound contour
of a particular tooth. Optionally, the base 30 is provided with
means for enhancing the bond between the connector member 24 and
the selected adhesive, such as a roughened or dimpled surface, a
surface having particles (irregularly-shaped or regularly-shaped)
fixed to the base 30, structure for providing a mechanical
interlock with the adhesive when hardened, chemical bond-enhancing
means or any combination of the foregoing.
[0079] The connector member 24 includes a body 32 that is connected
to the base 30. The body 32 has a neck portion 34 that presents an
undercut region. The body 32 also includes a bulbous outer head 36
that is connected to the neck 34.
[0080] Preferably, the connector member 24 is made as a single,
unitary component such that the body 32 is integrally connected to
the base 30. Preferably, the connector member 24 is integrally made
of an aesthetic material such as a material that is translucent or
transparent to light in the visible wavelengths. As another option,
the connector member 24 has a color that matches the color of the
patient's adjacent dentition. If the connector member 24 is made of
a transparent or translucent material, the material preferably
transmits sufficient light to enable the color of the patient's
underlying tooth to be visible through the front or labial side of
the connector member 24.
[0081] Examples of suitable materials for constructing the
connector member 24 include ceramic materials, such as single
crystal alumina and polycrystalline alumina. Alternatively, the
connector member 24 may be made of a polymeric material such as
polycarbonate. Optionally, the polymeric material is reinforced
with glass fibers. Suitable ceramic materials are described, for
example, in U.S. Pat. Nos. 4,954,080 and 6,648,638. Suitable
polymeric materials are described, for example, in U.S. Pat. No.
5,445,770.
[0082] The arch member 22 includes a row of couplings or
receptacles 38, one of which is designated in FIG. 10. The
receptacles 38 are spaced apart from each other along the length of
the arch member 22. As depicted in FIG. 7, each of the receptacles
38 is an opening that receives the head 36 of a respective
connector member 24. Each of the receptacles 38 has a configuration
adapted to releasably receive the head 36 in snap-fit relation.
Consequently, the arch member 22 can be disconnected from the
connector members 24 when desired.
[0083] The exemplary receptacles 38 shown in FIG. 7 surround the
head 36 of each connector member 24 along the buccolabial,
occlusal, mesial, gingival and distal sides of each head 36.
However, other constructions are also possible. For example, the
receptacles 38 may extend completely through the arch member 22
such that the receptacles 38 comprise apertures and buccolabial
sides of the heads 36 are exposed when viewing the brace 20 in a
lingual direction.
[0084] The arch member 22 illustrated in FIG. 7 is shown in
enlarged cross-sectional view in FIG. 10. In this embodiment, the
arch member 22 is made of a single layer of polymeric material
having sufficient resiliency to receive the connector members 24 in
snap-fit relation. To this end, the polymeric material deforms to
enlarge the opening of the receptacle 38 as the arch member 22 is
urged in a lingual direction in order to receive the head 36 of the
respective connector member 24.
[0085] The arch member 22 is preferably made of an aesthetically
pleasing material such as translucent, transparent or tooth-colored
polymeric materials. If the arch member 22 is made of a translucent
or transparent material, the material preferably transmits
sufficient light to enable the color of the patient's underlying
dentition to be visible through the front or labial side of the
arch member 22. Optionally, reinforcing fibers such as glass fibers
can be embedded in the polymeric material of the arch member 22.
Suitable materials for making the arch member 22 include the
polymeric materials described above in connection with the tray
10.
[0086] Preferably, the arch member 22 is capable of changing from a
first state that facilitates removal and/or installation of the
arch member 22 to a second state that facilitates orthodontic
treatment. The change in state may comprise, for example, a change
in material property or a change in shape, and is preferably
induced by an environmental change that can be carried out in the
patient's oral cavity. The change in state may occur throughout the
arch member 22 or only in selected portions of the arch member
22.
[0087] As one example, the arch member 22 may comprise a shape
memory polymer such as "Calo-MER" from Polymer Technology Group,
elastic memory composite ("EMC") from Composite Technology
Development, Inc. or "Veriflex" from Cornerstone Research Group.
These materials have both a high and a low temperature transition.
For instance, the polymeric material may have a lower glass
transition temperature that is in the range of about 23.degree. C.
to about 37.degree. C., and more preferably in the range of about
25.degree. C. to about 35.degree. C., and a higher transition
temperature that is in the range of about 40.degree. C. to about
50.degree. C. The arch member 22 is shaped to conform to a model of
the patient's teeth in desired positions at a temperature above the
higher transition temperature, and then held in that shape as it is
cooled to a temperature below its higher transition temperature.
Next, the arch member 22 is shaped to conform to a model of the
patient's teeth in current conditions at a temperature that is
between the high and low transition temperature, and held in that
shape while it is cooled to a temperature below the lower
transition temperature. Such construction facilitates the initial
connection of the arch member 22 to the connector members 24, such
as in instances where the initial connection is carried out before
the arch member 22 approaches body temperature. If the lower
transition temperature is between room temperature and body
temperature, the material will undergo a change in state once the
arch member 22 is placed in the oral cavity and will subsequently
provide forces for moving the teeth toward desired positions.
[0088] As another example, the arch member 22 may be made of a
material that has a glass transition temperature above body
temperature, and is shaped to provide for easy installation or
removal at temperatures above its glass transition temperature. In
this example, the arch member 22 is kept at a temperature below its
transition temperature before installation. When it is desired to
remove the arch member 22, it is warmed to a temperature above its
glass transition temperature.
[0089] Alternatively, the arch member 22 may be constructed of
homopolymers, cross-linked homopolymers, copolymers, cross-linked
copolymers, or blends thereof with inherent memory as described in
U.S. Pat. No. 6,183,248. Optionally, the material may have only a
single transition temperature. To form the memory removal
mechanism, these materials may be formed into a strip that loosely
approximates the shape of the arch. Once formed into this arch
shape, the strip is shaped at a temperature above its transition
temperature such that it will deliver desired forces to the teeth,
held in that shape and then cooled to a temperature below its
transition temperature. Once the strip is in the mouth, heating the
strip above the glass transition temperature will loosen it from
the appliances. The change in state may also be carried out by
methods other than a temperature change. For instance, the
polymeric material may change its state when subjected to an
aqueous buffer solution having a predetermined pH ratio.
Alternatively, the change in state may occur when the polymeric
material absorbs liquid as a result of a change in ionic strength
or upon exposure to radiation from a source of light. The change in
state may be a change in shape such as expansion or shrinkage, and
may also or in the alternative provide a change in material
property such as rigidity (i.e. flexural rigidity) or durometer
hardness.
[0090] The change in state may be selected to facilitate reception
or disengagement of the heads 36 in the respective receptacles 38.
For example, the change in state may provide an enlargement of the
openings to the receptacles 38 when desired, so that less force is
needed to insert the heads 36 in the receptacles. Once the
insertion is complete, a reversal of the change in state contracts
the openings in order to reduce the probability of unintentional
detachment of the heads 36 from the arch member 22 during the
course of treatment.
[0091] Other suitable polymeric materials that undergo a change in
state are described in U.S. Pat. Nos. 6,183,248, 5,506,300 and
6,388,043, and U.S. Patent Application Publications Nos. U.S.
2003/0157454 and 2003/0055198.
[0092] The arch member 22 may also be made of a multi-component
material comprising multiple layers. As one example, some of the
layers or components could undergo a change in state (such as a
glass transition) to reduce the modulus of the arch member 22 for
facilitating installation or removal of the arch member 22, while
other layers or components remain rigid to help maintain the shape
of the arch member 22. For instance, one layer may have a
transition temperature of about 150.degree. C. while a second layer
may have a transition temperature of about 40.degree. C.
Additionally, one or more of the layers could vary in thickness in
different regions along the length of the arch member 22. Examples
of suitable multi-component materials are described in the
above-mentioned U.S. Pat. No. 6,183,248.
[0093] The materials described above for making the arch member 22
along with the methods of constructing the arch member 22 may be
used as well for making trays according to other embodiments of the
invention, including the tray 10.
[0094] Preferably, each arch member 22 of the series has a geometry
identical to the geometry of at least one other, and preferably all
of the arch members of the series. The geometry of the arch member
22 when relaxed corresponds to the geometry necessary to move the
teeth to the desired final positions. When the arch member 22 is
placed on the connector members 24, however, the geometry of the
arch member 22 is changed to a temporary shape corresponding to the
shape of the tooth arrangement prior to reaching the desired
intermediate or final arrangement, such as the current tooth
arrangement. The resilient properties of the polymeric material
function to exert forces on the teeth 26 as necessary to shift the
teeth to the desired intermediate or final arrangement.
[0095] As treatment progresses and as the teeth 26 move closer to
their desired final positions, the arch member 22 is removed from
the connector members 24 and replaced with another arch member from
the same series. The second arch member has a stiffness that is
greater than the stiffness of the first arch member and
consequently provides greater force on the teeth per unit
displacement than the force provided by the first arch member. The
stiffness may be varied by any of the methods described above in
connection with the trays 10, 10a, 10b.
[0096] Preferably, the arch member 22 is connected to the connector
members 24 such that the arch member 22 may exert forces on the
connector members 24 and hence on the underlying teeth 26 in a
number of different directions. For example, the arch member 22 can
preferably exert forces as may be needed to move the connector
members 24 in either or both translation and rotation with respect
to three mutually perpendicular reference axes. As a result, the
teeth 26 may be subjected to tipping, torquing or angulation
movements as desired. To this end, the heads 36 and the receptacles
38 preferably have matching polygonal shapes, matching key and
keyway shapes or other interlocking configurations that facilitate
transmitting the desired forces from the arch member 22 to the
connector members 24 and ultimately to the underlying teeth.
[0097] In addition to the arch member 22, or as an alternative, the
connector members 24 may be made of a material that changes from a
first state to a second state, wherein the first state facilitates
coupling or uncoupling of the connector members 24 from the arch
member 22 and the second state facilitate orthodontic treatment.
For example, the connector members 24 may be made of a shape memory
material as described above, and contracts in shape when cooled in
order to ease insertion of the heads of the connector members 24
into the receptacles 38.
[0098] Additional aspects of the brace 20, including alternative
constructions of the arch member 22 and the connector members 24,
are set out in applicant's pending U.S. patent application entitled
"ORTHODONTIC BRACE WITH POLYMERIC ARCH MEMBER", Ser. No. 10/865,649
filed Jun. 10, 2004.
[0099] A system for moving teeth of a patient's dental arch from a
first tooth arrangement to a second tooth arrangement according to
still another embodiment of the invention comprises a plurality of
resilient appliances or arch members, an exemplary one of which is
the arch member 40 shown in FIGS. 11-13. In this embodiment, the
arch member 40 is connected to a set of orthodontic brackets 42,
each of which is fixed to a corresponding one of the patient's
teeth 44. The arch member 40 in combination with the brackets 42
comprises an orthodontic brace that is broadly designated by the
numeral 46.
[0100] Examples of suitable brackets 42 are illustrated in enlarged
view in FIG. 13. The illustrated brackets 42 are known as a
"self-ligating" brackets and are similar to the appliances
described in U.S. Pat. Nos. 6,302,688 and 6,582,226. Each bracket
42 has an elongated archwire slot 50 that extends across the
bracket 42 in a generally mesial-distal direction.
[0101] The exemplary self-ligating brackets 42 illustrated in FIGS.
11 and 13 have a latch 52 for releasably retaining an archwire or
arch member (such as arch member 40) in the archwire slot 50. In
this embodiment, the latch 52 comprises a pair of resilient clips
53 having a generally "C"-shaped configuration. Preferably, the
clips 53 are sufficiently flexible to enable the practitioner to
insert the arch member 40 in the archwire slot 50 by pressing the
same in a lingual direction such that the sides of the clips 53
deflect outwardly and away from each other. Once the arch member 40
is clear of the outer arm portions of the clips 53 and is located
in the archwire slot 50, the sides of the clips 53 self-deflect and
spring back toward each other to their normal closed orientation in
order to retain the arch member 40 in the archwire slot 50.
[0102] Preferably, the sides of the clips 53 deflect outwardly in
enable the latch 52 to assume a slot-open orientation and release
the arch member 40 from the archwire slot 50 whenever the force
exerted by the arch member 40 on the bracket 42 exceeds a certain
minimum value. This minimum value is sufficiently high to prevent
the arch member 40 from unintentionally releasing from the archwire
slot 50 during the normal course of orthodontic treatment. As such,
the arch member 40 can exert forces on the bracket 42 sufficient to
carry out the intended treatment program and move the associated
tooth as desired. Further details and additional options for the
brackets 42 are set out in the aforementioned U.S. Pat. Nos.
6,302,688 and 6,582,226.
[0103] Other types of self-ligating brackets are also possible. For
example, the bracket 42 may be identical or similar to the
self-ligating appliances described or referenced in U.S. Pat. Nos.
4,248,588, 4,492,573, 4,712,999 and 5,711,666.
[0104] As another alternative, the bracket 50 need not be a
self-ligating bracket. For example, the bracket may lack a latch
and be provided with two or more projections known as "tiewings"
that are located on opposite sides of the archwire slot. In
practice, the arch member 40 is retained in the archwire slot of
such a bracket by extending a ligature around the tiewings as well
as over the arch member 40 in order to retain the latter in the
archwire slot. Suitable ligatures include tiny, elastomeric O-ring
ligatures as well as sections of small-diameter metallic wire with
ends that are twisted together to form a loop. As yet other
options, the brackets may be replaced by buccal tubes or any other
type of tooth-connecting member that has a passage or slot for
receiving the arch member 40.
[0105] The arch member 40 is shown alone in FIG. 12. The arch
member 40 includes an elongated body 54 that is made of a resilient
material and has an overall, generally "U"-shaped configuration in
plan view. Optionally, the body 54 when relaxed extends along a
reference plane that is parallel to the desired occlusal plane of
the patient.
[0106] As depicted in FIG. 12, the body 54 includes a series of
enlarged sections 56 that are connected together by narrowed
sections 58. As shown, the cross-sectional area of the enlarged
section 56 is larger than the cross-sectional area of the narrowed
section 58. Such construction presents a series of couplings or
notches 60 that are spaced along the length of the body 54. Each
notch 60 extends inwardly from an outer edge of the arch member 40
in a direction toward the curved, central longitudinal axis of the
arch member 40.
[0107] In the illustrated embodiment, the notches 60 are located
along an occlusal edge (i.e., an edge facing the outer tips of the
patient's teeth) of the arch member 40 as well as along a gingival
edge (i.e., an edge facing the gums or gingiva of the patient) of
the arch member 40. However, other constructions are also possible.
For example, the narrowed sections 58 could be located along the
occlusal edge of the arch member 40 such that the notches 60 are
only present along the gingival edge of the arch member 40.
[0108] In this embodiment, the enlarged sections 56 as well as the
narrowed sections 58 have a cross-sectional shape that is generally
rectangular with rounded corners. However, other constructions are
also possible. For example, the cross-sectional shapes of the
sections 56, 58 may be elliptical, oval or circular. Combinations
of such shapes are also possible. For example, the enlarged
sections 56 may have an oval shape in cross-section, while the
narrowed sections 58 may have a generally rectangular configuration
in cross-section. As used herein with reference to the arch member
40, the term "cross-section" means a cross-section that is
generally perpendicular to the curved, central longitudinal axis of
the arch member 40.
[0109] The narrowed sections 58 are received within the archwire
slots 50 of the bracket 42. To this end, and in this embodiment,
the narrowed sections 58 have an overall size or height in an
occlusal-gingival direction that is less than the occlusal-gingival
size or height of the archwire slot 50. The narrowed sections 58
also have an overall thickness in a buccolabial-lingual direction
that is less than the distance between the bottom or lingual side
of the archwire slot 50 and the outer arm portions of the clip 53
so that the clip 53 may close to retain the arch member 40 once the
narrowed section 58 is received in the archwire slot 50.
[0110] Preferably, the cross-sectional configuration of the
narrowed section 58 is complemental to the cross-sectional
configuration of the archwire slot 50. For example, the archwire
slot 50 has a rectangular shape, and the narrowed section 58 has a
matching rectangular shape that is just slightly smaller, such as
0.001 inch or 0.025 mm in height and width. As a result, the
narrowed section 58 substantially fills the archwire slot 50 and
provides good control over movement of the associated tooth without
undue tolerance or "slop".
[0111] The body 54 has a major cross-sectional axis and a minor
cross-sectional axis when considered in reference planes
perpendicular to the longitudinal axis of the body 54 and between
adjacent notches 60. For example, the enlarged section 56 of the
body 54 has a major cross-sectional axis that extends in a
generally vertical direction viewing FIG. 13, and a minor
cross-sectional axis that extends in a generally horizontal
direction viewing FIG. 13. Consequently, the body 54 adjacent the
notch 60 (i.e., in areas next to the notch 60 in a
occlusal-gingival direction) has an overall size or height in an
occlusal-gingival direction that is less than the length of the
major cross-sectional axis.
[0112] However, the enlarged section 56 of the body 54 need not
necessarily have a major cross-sectional axis and a minor
cross-sectional axis. Instead, the enlarged section 56 may have a
vertical cross-sectional axis and a horizontal cross-sectional axis
that are equal in length. For example, the cross-sectional shape of
the enlarged section 56 may be square or circular.
[0113] In the embodiment illustrated in FIGS. 11-13, the thickness
of the body 54 when considered in directions along a
buccolabial-lingual reference axis is non-uniform along the length
of the body 54, such that the thickness of the enlarged sections 56
is greater than the thickness of the narrowed sections 58. Other
constructions are also possible. For example, the enlarged sections
56 may have a thickness that is equal or substantially equal to the
thickness of the narrowed sections 58 in directions along a
buccolabial-lingual reference axis. In other words, the body 54
adjacent the notch 60 may have an overall size in a
buccolabial-lingual direction that is the same as the length of the
minor cross-sectional axis.
[0114] With reference to FIG. 13, each of the notches 60 has a
certain width in a mesial-distal direction (i.e., in directions
along the length of the dental arch, or along the length or central
axis of the body 54). The width of the notches 60 is at least as
great as the length of the corresponding archwire slots 50
(preferably including the space within the clips 53) so that the
narrowed sections 58 can be received in the archwire slots 50. In
this manner, the notches 60 serve as receptacles to receive
respective brackets 42. Optionally, the width of the notches 60 is
greater than the length of the archwire slots 50 in order to enable
limited, relative sliding movement of the bracket 42 along the
longitudinal axis of the body 54. Alternatively, the width of the
notches 60 is substantially equivalent to the length of the
archwire slots 50. As an additional option, the width of some of
the notches 60 may be substantially equivalent to the length of
some of the archwire slots 50, while the width of the remaining
notches 60 may be greater than the length of the remaining archwire
slots 50. Furthermore, the width of the notches 60 may vary along
the length of the arch member 40 in corresponding relation to the
variation in width of the respective bracket 42.
[0115] In instances where the brackets 42 are to be mounted on or
near the mesial-distal center of the respective teeth, the
centerline spacing between adjacent notches 60 generally
corresponds to the centerline distance between corresponding,
adjacent teeth 44 of the dental arch 45. Consequently, the
centerline spacing between adjacent notches 60 also generally
corresponds to the centerline distance between corresponding,
adjacent brackets 42 located on the dental arch 45. In FIG. 13,
this centerline spacing between adjacent notches 60 is designated
by the letter "d" and preferably is identical or substantially
identical to the centerline spacing between adjacent teeth 44.
Preferably, this spacing is identical for each of the arch members
of the series.
[0116] Preferably, the series of arch members including the arch
member 40 for a particular patient is selected from an inventory of
pre-manufactured arch members 40 that are constructed according to
a statistical analysis similar to the analysis described above in
connection with the tray 10. For instance, a practitioner may
determine the best series of arch members to use from a set of
pre-manufactured series of arch members by measuring the width of
each of the patient's teeth and then using a numerical analysis to
facilitate selection of an optimal pre-manufactured arch member
series.
[0117] The body 54 of the arch member 40 may be made of any one of
a number of suitable materials, including the polymeric materials
described above in connection with the tray 10 and the arch member
22 as well as metallic materials. Preferred materials include
aesthetic polymers such as translucent, transparent or
tooth-colored polymers. Examples of suitable polymers include
polycarbonates, polyurethanes, silicones, latex, fluoropolymer and
polyolefins. Optionally, fibers such as glass fibers can be
embedded in the polymeric material. For instance, short fibers
having a length equal to the length of the notches 60 may be placed
in the narrowed sections 58 and oriented in a mesial-distal
direction. As an additional option, one or more metallic wires can
be embedded in the polymeric material, and optionally extend along
the entire length of the body 54.
[0118] As another option, the body 54 may comprise a shape memory
polymer such as "Calo-MER" from the Polymer Technology Group,
elastic memory composite ("EMC") from Composite Technology
Development, Inc. or "Veriflex" from Cornerstone Research Group
("CRG"). As an example, the body 54 may be made using a shape
memory polymer such that the arch member 40 has a shape at room
temperature that corresponds to the current shape of the patient's
teeth. Once the arch member 40 is placed in the patient's oral
cavity and the arch member body 54 rises in temperature to a
temperature above its glass transition temperature and to a
temperature approximating body temperature, the shape memory
characteristics of the polymer cause the arch member 40 to move the
teeth to desired positions. Such construction facilitates the
initial connection of the arch member 52 to the brackets 54, such
as in instances where the initial connection is carried out before
the arch member 52 approaches body temperature.
[0119] As yet another option, the body 54 may be made of a metallic
material such as stainless steel, nitinol or a cobalt-based nickel
alloy. As one example, the body 54 may have a coiled configuration
similar to the shape of a compression spring to facilitate
compression of the body 54 in directions along its longitudinal
axis. As another example, the body may comprise multiple strands of
metallic wires that are braided or twisted together, with openings
that are similar to openings of a compression spring to enable
compression of the body 54.
[0120] Preferably, the arch member 40 is constructed such that the
resiliency of the material of the body 54 provides the desired
tooth movement without substantial need for relative sliding
movement between the arch member 40 and the brackets 42. For
example, the arch member 40 may be constructed so that its shape
when relaxed corresponds to the desired shape of the dental arch 45
when all of the teeth 44 have been moved to their intended
positions, with the notches 60 being arranged to properly locate
each tooth 44 at desired final positions along the dental arch 45.
This construction helps to avoid problems that are normally
associated with the sliding mechanics observed between conventional
archwires and orthodontic appliances, such as friction, bending of
the archwire, gouging of the archwire and the like.
[0121] The series of arch members including the arch member 40 are
used during different stages of an orthodontic treatment program
for a particular patient. In particular, the stiffness of the arch
members used in the later stages of treatment are stiffer than the
arch members used in the earlier stages of treatment. The variation
in stiffness may be provided by changing the composition of the
arch member, by changing the processing methods used to make the
arch member, by changing the shape of the arch member, or by any
combination of the foregoing as well as by other methods as well.
However, preferably at least some and more preferably all of the
arch members in any one series have identical geometries when
relaxed. Other aspects of the series of arch members, such as the
relative orientation of the couplings or notches 60, are similar to
corresponding aspects of the series of trays mentioned above.
[0122] All of the patents, patent applications and other
publications identified herein are expressly incorporated by
reference. Additionally, those skilled in the art will recognize
that many modifications and alternative constructions may be made
without departing from the essence of this invention. Accordingly,
the invention should not be deemed limited to the specific
embodiments described in detail above, but instead only by a fair
scope of the claims that follow along with their equivalents.
* * * * *