U.S. patent application number 13/580876 was filed with the patent office on 2013-03-14 for dynamic virtual articulator.
This patent application is currently assigned to 3Shape A/S. The applicant listed for this patent is Christophe Vasiljev Barthe, Rune Fisker, Kasper Kabel Kristensen, Tommy Sanddal Poulsen. Invention is credited to Christophe Vasiljev Barthe, Rune Fisker, Kasper Kabel Kristensen, Tommy Sanddal Poulsen.
Application Number | 20130066598 13/580876 |
Document ID | / |
Family ID | 44506138 |
Filed Date | 2013-03-14 |
United States Patent
Application |
20130066598 |
Kind Code |
A1 |
Fisker; Rune ; et
al. |
March 14, 2013 |
DYNAMIC VIRTUAL ARTICULATOR
Abstract
Disclosed is a computer-implemented method of using a dynamic
virtual articulator for simulating occlusion of teeth, when
performing computer-aided designing of one or more dental
restorations for a patient, where the method comprises the steps
of: providing the virtual articulator comprising a virtual
three-dimensional model of the upper jaw and a virtual
three-dimensional model of the lower jaw resembling the upper jaw
and lower jaw, respectively, of the patient's mouth; providing
movement of the virtual upper jaw and the virtual lower jaw
relative to each other for simulating dynamic occlusion, whereby
collisions between teeth in the virtual upper and virtual lower jaw
occur; wherein the method further comprises: providing that the
teeth in the virtual upper jaw and virtual lower jaw are blocked
from penetrating each other's virtual surfaces in the
collisions.
Inventors: |
Fisker; Rune; (Virum,
DK) ; Barthe; Christophe Vasiljev; (Copenhagen N,
DK) ; Kristensen; Kasper Kabel; (Vanlose, DK)
; Poulsen; Tommy Sanddal; (Allerod, DK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Fisker; Rune
Barthe; Christophe Vasiljev
Kristensen; Kasper Kabel
Poulsen; Tommy Sanddal |
Virum
Copenhagen N
Vanlose
Allerod |
|
DK
DK
DK
DK |
|
|
Assignee: |
3Shape A/S
Copenhagen K
DK
|
Family ID: |
44506138 |
Appl. No.: |
13/580876 |
Filed: |
February 17, 2011 |
PCT Filed: |
February 17, 2011 |
PCT NO: |
PCT/DK2011/050047 |
371 Date: |
November 29, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61307934 |
Feb 25, 2010 |
|
|
|
61334681 |
May 14, 2010 |
|
|
|
61383840 |
Sep 17, 2010 |
|
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Current U.S.
Class: |
703/1 |
Current CPC
Class: |
A61C 19/045 20130101;
A61C 19/05 20130101; A61C 9/0053 20130101; A61C 13/0004 20130101;
G16H 20/40 20180101; A61C 9/0086 20130101; A61C 11/00 20130101 |
Class at
Publication: |
703/1 |
International
Class: |
G06F 17/50 20060101
G06F017/50 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 25, 2010 |
DK |
PA 2010 00156 |
May 14, 2010 |
DK |
PA 2010 00425 |
Sep 17, 2010 |
DK |
PA 2010 00835 |
Claims
1. A computer-implemented method of using a dynamic virtual
articulator for simulating occlusion of teeth, when performing
computer-aided designing of one or more dental restorations for a
patient, where the method comprises the steps of: providing the
virtual articulator comprising a virtual three-dimensional model of
the upper jaw and a virtual three-dimensional model of the lower
jaw resembling the upper jaw and lower jaw, respectively, of the
patient's mouth; providing movement of the virtual upper jaw and
the virtual lower jaw relative to each other for simulating dynamic
occlusion, whereby collisions between teeth in the virtual upper
and virtual lower jaw occur; wherein the method further comprises:
providing that the teeth in the virtual upper jaw and virtual lower
jaw are blocked from penetrating each other's virtual surfaces in
the collisions.
2. The computer-implemented method according to claim 1, wherein
the method further comprises simultaneous modeling of the one or
more dental restorations and collision testing of the virtual upper
jaw and virtual lower jaw.
3-4. (canceled)
5. The computer-implemented method according to claim 1, wherein
the method further comprises fixing the virtual upper jaw to the
occlusal axis such that the virtual lower jaw is configured to move
relative to the virtual upper jaw.
6. The computer-implemented method according to claim 1, wherein
the method further comprises defining a search structure on the
virtual upper jaw configured for searching on predefined circular
paths around the occlusal axis for detecting collisions with the
surface of the lower jaw model.
7-9. (canceled)
10. The computer-implemented method according to claim 1, wherein
the part of the one or more dental restoration which causes a
collision is configured to be automatically removed from the
respective virtual jaw.
11. The computer-implemented method according to claim 1, wherein
the method further comprises that the movement of the virtual upper
jaw and the virtual lower jaw relative to each other is configured
to be digitally recorded.
12-15. (canceled)
16. The computer-implemented method according to claim 1, wherein
the method further comprises aligning the virtual upper jaw and
virtual lower jaw to correspond to the anatomical alignment of the
jaws in the mouth of the patient.
17-20. (canceled)
21. The computer-implemented method according to claim 1, wherein
the method further comprises positioning a virtual alignment plane
relative to the virtual upper jaw and the virtual lower jaw, where
the virtual upper jaw and virtual lower jaw defines a virtual model
of the set of teeth, wherein the method comprises the steps of:
visualising the virtual alignment plane and the virtual upper jaw
and virtual lower jaw; and automatically positioning the virtual
alignment plane and the virtual lower jaw and virtual upper jaw
relative to each other based on one or more parameters.
22-39. (canceled)
40. The computer-implemented method according to claim 1, wherein
the positioning of the virtual alignment plane relative to the
virtual model of the set of teeth is configured to be performed by
the operator by selecting one or more virtual points relative to
the virtual model of the set of teeth within which point(s) the
virtual alignment plane should be moved to.
41-55. (canceled)
56. The computer-implemented method according to claim 21, wherein
the virtual alignment plane and/or the virtual model of the set of
teeth is/are semi-transparent or translucent such that both the
virtual alignment plane and the virtual set of teeth are visible
simultaneously.
57. (canceled)
58. The computer-implemented method according to claim 1, wherein
the method further comprises that during the movement of the
virtual upper jaw and the virtual lower jaw relative to each other
all the collisions occurring between teeth are registered, and
after the movement is finished, modeling of the collision points of
the restorations is performed.
59-60. (canceled)
61. The computer-implemented method according to claim 1, wherein
restorations are penetrable.
62. (canceled)
63. The computer-implemented method according to claim 1, wherein
the method comprises providing that the designed restoration(s) is
blocked from being penetrable when colliding with the opposite
virtual jaw.
64-67. (canceled)
68. The computer-implemented method according to claim 1, wherein a
predefined motion of the virtual upper jaw and the virtual lower
jaw relative to each other is configured to be played.
69-72. (canceled)
73. The computer-implemented method according to claim 21, wherein
the method further comprises positioning a virtual alignment plane
relative to the virtual upper jaw and the virtual lower jaw, where
the virtual upper jaw and virtual lower jaw defines a virtual model
of the set of teeth, wherein the method comprises the steps of:
visualising the virtual alignment plane and the virtual upper jaw
and virtual lower jaw; and automatically positioning the virtual
alignment plane and the virtual lower jaw and virtual upper jaw
relative to each other.
74-77. (canceled)
78. A computer-implemented method of using a dynamic virtual
articulator for simulating occlusion of teeth, when performing
computer-aided orthodontic treatment planning for a patient, where
the method comprises the steps of: providing the virtual
articulator comprising a virtual three-dimensional teeth model
comprising the upper jaw, defined as the virtual upper jaw, and a
virtual three-dimensional teeth model comprising the lower jaw,
defined as the virtual lower jaw, resembling the upper jaw and
lower jaw, respectively, of the patient's mouth; providing movement
of the virtual upper jaw and the virtual lower jaw relative to each
other for simulating dynamic occlusion, whereby collisions between
teeth in the virtual upper and virtual lower jaw occur; wherein the
method further comprises: providing that the teeth in the virtual
upper jaw and virtual lower jaw are blocked from penetrating each
other's virtual surfaces in the collisions.
79. The computer-implemented method according to claim 78, wherein
treatment planning in orthodontics comprises segmenting teeth,
moving teeth, and/or simulating motion of jaws and teeths.
80. The computer-implemented method according to claim 78, wherein
the method comprises registering the trace of collisions, and based
on this the orthodontic treatment, e.g. movement of the different
teeth, is planned.
81. The computer-implemented method according to claim 78, wherein
the method comprises assigning a weight to one or more teeth.
82-86. (canceled)
87. The computer-implemented method according to claim 78, wherein
modelling of orthodontic appliances is configured to be
performed.
88. The computer-implemented method according to claim 78, wherein
the patient's occlusion with the modelled appliances is configured
to be simulated.
89-99. (canceled)
100. The computer-implemented method according to claim 78, wherein
the timewise sequence of events in the occlusion simulation is
registered.
101. (canceled)
102. The computer-implemented method according to claim 78, wherein
an occlusal compass generated by real dynamic occlusion in the
patient's mouth is transferred to the dynamic virtual
articulator.
103-113. (canceled)
114. The computer-implemented method according to claim 78, wherein
a CT scan of the patient's mouth is generated, and a virtual 3D
model of the patient's mouth is automatically generated based on
the scan, and occlusion is configured to be simulated based on the
3D CT model.
115-119. (canceled)
120. The computer-implemented method according to claim 78, wherein
a weight assigned to a tooth determines its functionality
importance in guiding the occlusion of the patient.
121-124. (canceled)
125. The computer-implemented method according to claim 78, wherein
occlusion of the present set of teeth is simulated, and one or more
designed restorations is/are optionally included in the
simulation.
126-130. (canceled)
131. The computer-implemented method according to claim 78, wherein
one or more contact criteria for occlusion is defined and used in
simulation of occlusion.
132-139. (canceled)
140. A virtual articulator system for simulating occlusion of
teeth, when performing computer-aided designing of one or more
dental restorations for a patient, where the system comprises:
means for providing the virtual articulator comprising a virtual
three-dimensional model of the upper jaw and a virtual
three-dimensional model of the lower jaw resembling the upper jaw
and lower jaw, respectively, of the patient's mouth; means for
providing movement of the virtual upper jaw and the virtual lower
jaw relative to each other for simulating dynamic occlusion,
whereby collisions between teeth in the virtual upper and virtual
lower jaw occur; wherein the system further comprises: means for
providing that the teeth in the virtual upper jaw and virtual lower
jaw are blocked from penetrating each other's virtual surfaces in
the collisions.
141-143. (canceled)
Description
FIELD OF THE INVENTION
[0001] This invention generally relates to a virtual articulator
and to a method of performing virtual articulation. More
particularly, the invention relates to a computer-implemented
method of using a dynamic virtual articulator for simulating
occlusion of teeth, when performing computer-aided designing of one
or more dental restorations.
BACKGROUND OF THE INVENTION
[0002] An articulator is a mechanical device which provides a
simplified geometrical model of the cranium for simulating the
relative movements of the human jaws for testing occlusion of
teeth. An articulator is used by a dental technician when modelling
dental restorations for a patient, and the dental technician may
alternate between modelling the restorations and evaluating the
function of the bite or occlusion using the articulator. For
testing collision of teeth in the upper and lower jaw, the dental
technician can use carbon copy paper placed between the teeth of
the two jaws in the articulator, and the colliding teeth will be
thus colored, when the jaws are moved.
[0003] Virtual articulators which are digital representations of
articulators are known as described below.
[0004] WO08113313A discloses a method for the production of a
denture comprising the following steps: collection of the biometric
data of a patient, namely, the toothed or untoothed mandible and
maxilla, the sizing of the jaws, the spatial position thereof
relative to the skull, the condyle inclination and the movement of
the mandible, and the recording of the mandible movement;
implementation of the data in a virtual articulator which is made
available in the main memory of the data processing equipment; CAD
construction of the individual articulator preformed parts and
dental molded bodies based on the collected patient data;
production of the individual articulator molded bodies and dental
molded bodies by means of a generative manufacturing process based
on the recorded biometric data; incorporation of the individual
articulator preformed parts and/or dental molded bodies into a
standardized articulator housing, or complete generative
manufacture of the articulator with individualized molded
bodies.
[0005] US2002048741 discloses a computer implemented method of
creating a dental model for use in dental articulation, the method
comprising the steps of: providing a first set of digital data
corresponding to an upper arch image of at least a portion of an
upper dental arch of a patient; providing a second set of digital
data corresponding to a lower arch image of at least a portion of a
lower dental arch of the patient; providing hinge axis data
representative of the spatial orientation of at least one of the
upper and lower dental arches relative to a hinge axis of the
patient; providing bite alignment data representative of the
spatial relationship between the upper dental arch and the lower
dental arch of the patient; aligning the upper arch image and the
lower arch image based on the bite alignment data; and creating a
reference hinge axis relative to the aligned upper and lower arch
images based on the hinge axis data.
[0006] US2004172150A discloses a system for designing a virtual
dental model comprising: a virtual articulator representing a three
dimensional model of a patient's upper and lower dental arches
including data defining a constraint of motion having a plurality
of degrees of freedom between said upper and lower dental arches; a
simulation analyzer to simulate said motion using said three
dimensional model and analyze resulting contacts on portions of
said upper and lower arches during said movement to provide contact
data, said resulting contacts being characterized by a sequence in
time of occurrence; and a designing module to design one of a
virtual prosthesis for one of said upper and lower arches and a
virtual desired dental modification using said contact data
acquired from said simulation analyzer and said virtual
articulator.
[0007] US2007207441 relates to four dimensional modeling of jaw and
tooth dynamics where methods and systems are described to digitally
model the 4-dimensional dynamics of jaw and tooth motion using
time-based 3-dimensional data. Complete upper and lower digital
models are registered to time-based 3-dimensional intra-oral data
to produce a true 4-dimensional model. Diagnostic and clinical
applications include balancing the occlusion and characterizing the
geometry of the temporomandibular joint. The 4-dimensional model is
readily combined with conventional imaging methods such as CT to
create a more complete virtual patient model. In one embodiment the
document discloses that a standard centric axis coordinate system
and a bite position is defined by: a) determining a lower occlusal
plane using the complete lower model; b) setting the lower occlusal
plane at a predetermined angle, approximately 15 degrees, to a
reference horizontal; c) orienting the model of the lower dental
arch with the jaw midline perpendicular to the centric axis; d)
using a predetermined axis-incisal distance to complete the
location of the lower model and the centric axis; and e)
positioning the upper model with respect to the lower using a scan
taken at a closed or bite position.
[0008] WO09133131A discloses a method of using a computer based
virtual articulator, the method comprising: loading a digital
dental model of a patient into a computer running a virtual
articulator simulation program, and simulating one or more virtual
functional movements, evaluate at least one parameter related to
the movement of the jaw when a dental modification is applied, the
at least one parameter related to the movement of the jaw being
selected from at least the amount of jaw movement in a certain
direction, the speed at which a certain jaw movement is carried out
and an angle around which a rotational jaw movement is carried
out.
[0009] It remains a problem to provide a virtual articulator which
imitates and resembles an articulator in an improved manner.
SUMMARY
[0010] Disclosed is a computer-implemented method of using a
dynamic virtual articulator for simulating occlusion of teeth, when
performing computer-aided designing of one or more dental
restorations for a patient, where the method comprises the steps
of:
[0011] providing the virtual articulator comprising a virtual
three-dimensional model of the upper jaw and a virtual
three-dimensional model of the lower jaw resembling the upper jaw
and lower jaw, respectively, of the patient's mouth;
[0012] providing movement of the virtual upper jaw and the virtual
lower jaw relative to each other for simulating dynamic occlusion,
whereby collisions between teeth in the virtual upper and virtual
lower jaw occur;
[0013] wherein the method further comprises:
[0014] providing that the teeth in the virtual upper jaw and
virtual lower jaw are blocked from penetrating each other's virtual
surfaces in the collisions.
[0015] Disclosed is a computer-implemented method of using a
dynamic virtual articulator for simulating occlusion of teeth, when
performing computer-aided designing of one or more dental
restorations for a patient, where the method comprises the steps
of:
[0016] providing the virtual articulator comprising a virtual
three-dimensional teeth model comprising the upper jaw, defined as
the virtual upper jaw, and a virtual three-dimensional teeth model
comprising the lower jaw, defined as the virtual lower jaw,
resembling the upper jaw and lower jaw, respectively, of the
patient's mouth;
[0017] providing movement of the virtual upper jaw and the virtual
lower jaw relative to each other for simulating dynamic occlusion,
whereby collisions between teeth in the virtual upper and virtual
lower jaw occur;
[0018] wherein the method further comprises:
[0019] providing that the teeth in the virtual upper jaw and
virtual lower jaw are blocked from penetrating each other's virtual
surfaces in the collisions.
[0020] Consequently, it is an advantage that the virtual
articulator is allowed to only perform movements which resembles
and imitates the real-life situation in the mouth of a patient or
the situation when using a physical articulator, thus the relative
movement of the jaws are physiological realistic. Thus it is an
advantage that the teeth in the upper and lower jaws in the virtual
articulator resemble physical, solid teeth which can collide and
touch each other but not penetrate each other. The expression teeth
may mean the original teeth in the patient's mouth with and without
restorations and restorations which completely replace one or more
teeth. Teeth may mean the virtual teeth in the virtual upper and
lower jaw model to which no restoration(s) is/are designed. The
teeth in opposing jaw are thus not allowed to penetrate each
other's virtual surfaces, when they collide as part as the
occlusion simulation or test for which the virtual articulator is
used. The teeth in the virtual articulator are configured to
appear, act or behave as solid objects with an impenetrable surface
and with a physical extent corresponding to teeth in a physical
articulator. The articulated movements of the jaws are restricted
by disallowing jaws, and thus the teeth in the jaws, to penetrate.
The teeth in the jaws may be said to be impenetrable or to exhibit
impenetrability, which is a quality of matter whereby two bodies
cannot occupy the same space at the same time. Thus opposing teeth
in the upper and lower virtual jaw cannot occupy the same virtual
space at the same time.
[0021] It is an advantage that the virtual articulator is
configured to be a virtual geometric model, for example of and
thereby equivalent to a mechanical system comprising a physical
articulator. The virtual articulator automatically moves or allows
the user to move the two jaws relative to each other. This movement
is confined to the movement allowed by the articulator geometry.
The jaws may consist of both preparation scans and designed models.
Alternatively, the virtual articulation may be based on a generic
model, a physiologic model, free-movement without constraints
etc.
[0022] It is an advantage that the virtual articulator can be
utilized at any point in the design process of designing dental
restorations, such a crowns or bridges, whereby the size and shape
of the designed restorations can be tested to check if it is
correct, i.e. test whether there is space enough for the designed
restorations in the mouth, when the jaws are moving relative to
each other. Thus by means of simulating occlusion, the function of
the dental restorations are tested. A restoration may be a part of
one or more teeth, and therefore the expression "collisions between
teeth" is used in the present application, and this expression
therefore also comprises or means collision between a tooth and a
restoration, collision between restorations, collisions between
unmodified teeth etc. Thus a tooth can be both a tooth without a
restoration or with a restoration. Thus in this application the
term tooth and the term restoration may be used interchangeably
about a tooth with a restoration or of a restoration completely
replacing a tooth.
[0023] In some embodiments the method comprises optionally
providing that the designed restoration(s) is penetrable, when
colliding with the opposite virtual jaw.
[0024] In some embodiments the method comprises providing that the
designed restoration(s) is blocked from being penetrable when
colliding with the opposite virtual jaw.
[0025] In some embodiments the method comprises providing that the
designed restoration(s) is penetrable, when colliding with the
opposite virtual jaw.
[0026] It is an advantage that the restorations can be penetrable
or not when designing the restorations, depending on the preference
of the operator or user of the software.
[0027] It is an advantage that the movement of the virtual
articulator is restricted by the inability of the two jaws,
including designed models, to penetrate into each other, which is
provided to accurately model the grinding of the teeth against each
other during chewing and thereby recording contact areas. This
makes it possible to evaluate the functional aspects of the designs
at any given time in the design process, which is analogous to the
manual process using a physical articulator.
[0028] The virtual three-dimensional model of the upper jaw and
lower jaw, respectively, may comprise the entire jaw or arch or a
part of the entire jaw, corresponding to e.g. a number of teeth,
such as half of the teeth in the jaw.
[0029] The expressions jaw and arch may in some cases in this
application be used to denote the same physiologic region.
[0030] The present computer-implemented method may be implemented
and executed in a software program which performs the virtual
articulator simulation.
[0031] The virtual articulator simulates the movements of a
physical articulator or the movements of the real jaws in the mouth
of a patient, and besides not allowing penetration of opposing
teeth, the movement of the virtual articulator will also ensure
that after teeth collide, the next movement of the virtual jaws
will correspond to the movement of the teeth in the mouth or the
jaws in a physical articulator will perform after collisions, which
is continuing the direction of the motion taken the collisions into
account, i.e. direction, velocity, angle of impact etc.
[0032] In prior art only static occlusion of a bite may be provided
in a computer-implemented method, thus the upper and lower jaw may
only be represented in their neutral positions, and no relative
movement of them were possible.
[0033] Prior art discloses collisions between jaws, and the jaws
penetrate each other during collisions. In virtual prior art
collisions between virtual 3D teeth models, the models are shown to
be penetrable, because they are virtual models, whereby there are
no physical barriers between the models. However, according to the
present method, the collisions are made to resemble a real life
collision in the mouth or in a physical articulator. The present
method comprises reproducing collisions between upper and lower jaw
as real, physical collisions, where the colliding teeth cannot
penetrate each other but glide past each other, which is the
natural physical case. The colliding teeth can thus only contact
each other, not penetrate, as they are virtually solidified
physically instead of being represented as penetrable objects.
[0034] In some embodiments the method further comprises
simultaneous modeling of the one or more dental restorations and
collision testing of the virtual upper jaw and virtual lower
jaw.
[0035] The method may alternatively and/additionally comprise
designing one or more orthodontic procedures for the patient,
and/or designing one or more prosthetic procedures for the patient,
and/or performing a functional analysis of the patient's teeth.
[0036] In some embodiments the method further comprises automatic
modelling of dental restorations in opposite positions in the
virtual upper jaw and virtual lower jaw, when dental restorations
in opposite positions are requested.
[0037] In some embodiments the virtual upper jaw and virtual lower
jaw are configured to move relative to each other.
[0038] The movement or motion may be a free motion, a restricted or
constrained motion, a motion based on an articulator model, such as
a physical, mechanical articulator model etc.
[0039] In some embodiment the virtual upper jaw is fixed such that
the virtual lower jaw is configured to move relative to the virtual
upper jaw.
[0040] The virtual upper jaw may be fixed in the virtual space
comprising the virtual articulator and the upper and lower teeth
models.
[0041] In some embodiments the method comprises performing the
collision testing of the virtual upper jaw and virtual lower jaw
exclusively along the occlusal axis of the virtual articulator.
[0042] In some embodiments the method further comprises fixing the
virtual upper jaw to the occlusial axis such that the virtual lower
jaw is configured to move relative to the virtual upper jaw.
[0043] A common property of most physical articulators is that the
lower part holding the lower jaw is fixed to the occlusial axis,
because the lower part is resting on a table. The upper part can
then be moved relative to the lower part. It is an advantage that
according to the present method the upper jaw is fixed relative to
the occlusial axis, which resembles the anatomy of the human
cranium, where the upper jaw is fixed to the rest of the cranium
and the lower jaw can move relative to the upper jaw. However,
alternatively the lower jaw could be fixed to the occlusial
axes.
[0044] In some embodiments the method further comprises defining a
search structure on the virtual upper jaw configured for searching
on predefined circular paths around the occlusial axis for
detecting collisions with the surface of the lower jaw model.
[0045] In some embodiments the method further comprises that the
virtual lower jaw is configured to automatically move through at
least one predefined path of movement relative to the virtual upper
jaw.
[0046] In some embodiments the method further comprises detecting
the first position on the occlusial axis at which the virtual upper
jaw and the virtual lower jaw are in contact.
[0047] These embodiments are advantages because in general,
calculating collisions between complex 3D models and providing
response to collisions for preventing penetration is a
computationally expensive problem. However, the computation time
can be drastically improved, if suitable 3D search structures on
the models are computed prior to the collision tests. Examples of
such search structures are bounding volume hierarchies, such as
AABB-trees, and space partitioning structures, such as BSP-trees,
Octrees and kd-trees.
[0048] In physical articulators there are a number of degrees of
freedom and one of these degrees of freedoms of movement is given
by a rotation axis which models occlusion, also called the
occlusial axis.
[0049] It is an advantage that in the present virtual articulator,
it is sufficient to perform collision test and evaluate the
response along the occlusial axis, i.e. for any given configuration
of the other degrees of freedom, and thereby finding the first
position on the occlusial axis for which the two jaw models are in
contact. This reduces the dimensionality of the calculation problem
and allows for the use of more specialized search structures, which
are aimed at calculating the first point of intersection with a 3D
model along a given circular path around a static rotation axis.
Thus for each motion step along one of the other axes, i.e. for
each degrees of freedom, it may be calculated when and at which
points the teeth in the jaws will collide along the occlusial axis.
So for each movement of the jaws along any of the axes, the jaws
may in principle or calculation-wise be closed and then opened
along the occlusial axis for testing collision between teeth. Thus
predefined paths of movement along the occlusial axis may be
configured, where it may be calculated how, when, where the jaws
collide for different situations.
[0050] It is thus an advantage to construct a search structure on
the upper jaw model specialized at searching on circular paths
around the occlusial axis. For any configuration of the other
degrees of freedom, such a search structure may be used to perform
collision test and response along the occlusial axis by searching
from the surface of the lower jaw model. This makes real-time
collision test and response possible.
[0051] If the upper jaw and the search structure were not fixed,
the search structure would otherwise need to be updated or
recalculated, whenever the relative location of the jaw model and
the occlusial axis changed, which would make real-time simulation
infeasible.
[0052] In some embodiments the collisions are configured to be
registered and visually marked.
[0053] An advantage of this embodiment is that when the collision
points are registered and detected, entire surfaces of collision
points are obtained, and the dental restorations can be designed,
modeled or modified based on this. A surface of collision points
may be denoted the trace or the trace of motion.
[0054] In some embodiments collision points in a collision provides
a surface of collision points.
[0055] The surface of collision points may provide a trace of
motion.
[0056] The surface of collision points may be visualized and used
to design the restoration(s) with.
[0057] A collision depth map may be provided and updates with the
surface of collision points.
[0058] When unmodified teeth are simulated relative to each other,
their motion traces or their surfaces cannot penetrate each other.
The same may be the case for a restoration relative to an
unmodified tooth.
[0059] However, it may alternatively be the case that when a
restoration and an unmodified tooth are simulated relative to each
other, the motion surface of the restoration may penetrate the
unmodified tooth.
[0060] Thus the term collision surface or trace of collisions
points or collision points surface is used for both describing when
unmodified teeth are simulated to move relative to each where the
teeth collide and do not penetrate each other and for describing
when a restoration is simulated relative to unmodified teeth where
the restoration may penetrate the unmodified teeth, i.e. the
restoration and the unmodified may penetrate each other.
[0061] The simulated collisions or collision surfaces between
unmodified teeth may determine the motion which can be performed
between the upper and lower teeth models.
[0062] This determined motion may then be used and studied when
designing the restoration.
[0063] The virtually designed appliance or restoration can be cut
or designed relative to the collision trace motion.
[0064] In some embodiments the part of the one or more dental
restorations which causes a collision is configured to be
automatically removed from the respective virtual jaw.
[0065] Alternatively, the user can remove the part, e.g. a part of
material by selecting it manually in the software program
performing the virtual articulator simulation.
[0066] Traditionally, restorations were only made on one jaw at the
time, not on both jaws simultaneously or concurrently. According to
the present method e.g. a crown on a tooth in the upper jaw and a
bridge on teeth in the lower jaw, which are opposite to the tooth
in upper jaw, can now be designed simultaneously. Thus according to
the present method teeth, including opposing teeth in the upper and
lower jaw, can be designed, and evaluated with regard to collisions
and viewed simultaneously.
[0067] In some embodiments the method further comprises that the
movement of the virtual upper jaw and the virtual lower jaw
relative to each other is configured to be digitally recorded.
[0068] An advantage of this embodiment is that when recording the
movements, after modeling a restoration, the recording can be
played to test the modeling.
[0069] In some embodiments a predefined motion of the virtual upper
jaw and the virtual lower jaw relative to each other is configured
to be played.
[0070] In some embodiments the predefined motion comprises movement
in one or more of the directions:
[0071] protrusion;
[0072] retrusion;
[0073] laterotrusion to the right;
[0074] laterotrusion to the left;
[0075] mediotrusion to the right;
[0076] mediotrusion to the left;
[0077] latero-re surtrusion to the right;
[0078] latero-re surtrusion to the left.
[0079] In some embodiments the predefined motion is configured to
be automatically terminated based on one or more constraints.
[0080] The constraints may be determined by the boundaries of the
teeth. The constraints may be determined by the canines in the
upper and lower touching each other.
[0081] In some embodiments the method further comprises that during
the movement of the virtual upper jaw and the virtual lower jaw
relative to each other all the collisions occurring between teeth
are registered, and after the movement is finished, modeling of the
collision points of the restorations is performed.
[0082] Thus a movement of the jaws in a continuous motion is
performed, i.e. such that one jaw performs a motion completely
covering a plane of the other jaw, whereby all collisions between
the two jaws, which are possible when taking physiological
constraints into account, are registered. Thus the collisions are
accumulated, and after the movement is completed and all collisions
are registered, then modeling of the collisions points on the
restorations is performed. In prior art, a position of the jaws
relative to each other is selected, collisions for this position
are detected, modeling is performed of the restorations in these
collision points, and then a new position is selected, collisions
are detected for this position, modeling is performed for the
restorations with these collision points etc. Thus no movement, no
accumulated registration of collision point surfaces and no
possibility to perform a concurrent modeling of restorations based
on all collision points are disclosed or possible in prior art. In
prior art static occlusion can be detected, but not dynamic
occlusion or articulation. Thus in prior art, the jaws are in a
static position relative to each other, they can be said to be
locked relative to each other.
[0083] It is an advantage that the collisions are accumulated,
since this gives a collected representation of the contact points
or collisions. By viewing the collected representation of the
contact points and collisions the dental technician is capable of
performing a suitable modeling of all the restorations with
collision points.
[0084] Furthermore, it is an advantage that a movement of the jaws
relative to each other in a continuous motion is performed, since
this resembles the use of a physical articulator, which a dental
technician may be used to work with. Thus it easy for the dental
technician to learn to simulate occlusion in the computer program,
because the virtual simulation and modeling resemble the manual
simulation and modeling on a physical model using a physical
articulator.
[0085] In some embodiments automatic modeling of all collision
points of restorations are performed concurrently.
[0086] Thus modeling of restorations at each collision point can be
performed concurrently, simultaneously, at one go etc. Each
individual collision point does not need be modeled separately, but
some or all collisions points of restorations can be modeled
collectively. The modeling may comprise that the parts of the
restorations which were detected as contact points are removed,
which corresponds to manually removing material from a
restoration.
[0087] In some embodiments each collision point of a restoration is
modeled separately.
[0088] In some embodiments restorations are penetrable.
[0089] Thus teeth without restorations are impenetrable but the
restorations, e.g. the part of a tooth which is a restoration, may
be penetrable. This is an advantage when modeling the
restorations.
[0090] In some embodiments the virtual upper jaw and the virtual
lower jaw are configured to bounce back off each other after a
collision.
[0091] The trace of movement may be recorded, so it can be used in
the designing of the restoration(s).
[0092] In some embodiments the movement of the virtual upper jaw
and the virtual lower jaw relative to each other is configured to
be performed in real-time corresponding to natural articulator
movements.
[0093] In some embodiments the method further comprises selecting a
predefined geometrical model for the virtual articulator from among
a number of predefined geometrical models.
[0094] It is an advantage that the user can select a virtual
geometrical model from a number of predefined geometrical models,
since the models can represent physical, mechanical articulators of
specific brands; geometrical models which the user has defined,
standard geometrical models etc. Furthermore, the geometrical model
can be a physiologic or biologic model etc., such as a model of the
skull geometry. Thus the user can select a geometrical model which
suits him or the specific patient case. The selected geometrical
model may impose constraints on the movements, or the geometrical
model may provide free movement.
[0095] The selected geometrical model provides the basis for the
articulation and/or occlusion which can be tested or simulated.
[0096] In some embodiments the virtual dynamic articulator is
configured to be selected from among a number of virtual
articulators resembling physical articulators.
[0097] In some embodiments the method further comprises selecting a
number of degrees of freedom for the geometrical model.
[0098] In some embodiments the method further comprises aligning
the virtual upper jaw and virtual lower jaw to correspond to the
anatomical alignment of the jaws in the mouth of the patient.
[0099] This alignment may be defined as a standard alignment.
[0100] In some embodiments the anatomical alignment of the jaws is
determined by performing a measurement of the patient's facial
geometry.
[0101] In some embodiments the patient's facial geometry is
determined by performing a face scanning of the patient.
[0102] The face scanning may result in a three-dimensional (3D)
representation of the patient's face. The face scanning may
comprise single, still images or may comprise video comprising
sequences of still images representing the face in motion.
Alternatively and/or additionally the patient's specific facial
geometry can be determined by means of traditional face bow or face
arches using electronics and optics, where the face bows are
attached to e.g. the ears or on the outside of the jaw. Thus when
the patient moves his/her jaws, the face bows measure the
movements, and the mechanical articulator is adjusted according to
this. Movements may comprise swinging of the jaws, opening of the
mouth, dragging of the jaw forward, backwards etc.
[0103] In some embodiments the method further comprises that the
virtual lower jaw is configured to be moved by a user.
[0104] Alternatively, both the virtual jaws may be moved relative
to each other.
[0105] In some embodiments the virtual lower jaw is configured for
simulating movements in the following directions:
[0106] protrusion (direct forward movement);
[0107] laterotrusion and mediotrusion (forward-sidewards movements
to both left and right);
[0108] retrusion (direct backward movement); and
[0109] latero-re surtrusion (to both left and right);
[0110] Thus the movement may comprise:
[0111] protrusion;
[0112] retrusion:
[0113] laterotrusion to the right;
[0114] laterotrusion to the left;
[0115] mediotrusion to the right;
[0116] mediotrusion to the left;
[0117] latero-re surtrusion to the right;
[0118] latero-re surtrusion to the left.
[0119] In some embodiments the method further comprises positioning
a virtual alignment plane relative to the virtual upper jaw and the
virtual lower jaw, where the virtual upper jaw and virtual lower
jaw defines a virtual model of the set of teeth, wherein the method
comprises the steps of:
[0120] visualising the virtual alignment plane and the virtual
upper jaw and virtual lower jaw; and
[0121] automatically positioning the virtual alignment plane and
the virtual lower jaw and virtual upper jaw relative to each
other.
[0122] The virtual upper model and/or the virtual lower model may
be arranged in the virtual articulator first, and then the
alignment plane is positioned afterwards or vice versa.
[0123] The virtual alignment plane may also not be visualised, and
may thus be invisible or faded.
[0124] It is an advantage that the virtual models can be aligned
relative to a virtual alignment plane. The virtual alignment plane
may be determined e.g. based a plane in a mechanical articulator.
In a mechanical articulator there may be a marking, e.g
indentations in the vertical rods, for manually arranging a red
rubber-band. The rubber band is used to arrange, such as align, the
two physical models of the upper and lower teeth.
[0125] In some embodiments the automatic positioning is based on
one or more parameters.
[0126] In some embodiments the method further comprises positioning
a virtual alignment plane relative to the virtual upper jaw and the
virtual lower jaw, where the virtual upper jaw and virtual lower
jaw defines a virtual model of the set of teeth, wherein the method
comprises the steps of:
[0127] visualising the virtual alignment plane and the virtual
upper jaw and virtual lower jaw; and
[0128] automatically positioning the virtual alignment plane and
the virtual lower jaw and virtual upper jaw relative to each other
based on one or more parameters.
[0129] It is an advantage that the virtual alignment plane and the
virtual model of the teeth are positioned relative to each other
based on some parameters, because depending on which parameters
that are available for the specific patient and case, the relevant
available parameters can be used to perform the positioning. If no
specific parameters are available for the specific patient,
standard or default parameters may be used. But if specific
parameters are available for the patient, these parameters may be
used such that the result can be achieved faster and with a better
result. As mentioned below, the patient-specific parameters may be
obtained with a facebow providing information about static
occlusion, with an electronic facebow providing information about
static and dynamic occlusion, with a face scanner also providing
information about static and dynamic occlusion etc.
[0130] The virtual alignment plane may be defined or determined in
different ways. The alignment plane may be flat, level or even, or
curved, irregular, uneven or non-uniform etc. The alignment plane
may follow or comply with the shape of the incisal or biting edges
and/or cusps of the teeth.
[0131] The alignment plane may for example be the curve of Spee.
The curve of Spee is defined by that the cusp tips and incisal
edges of the teeth align so that there is a smooth, linear curve
when viewed from the lateral aspect. The lower curve of Spee is
concave whereas the upper curve is convex. Curve of Spee may be
called a compensating curve of the dental arch.
[0132] The set of teeth may be an entire set of teeth covering all
teeth in a patients mouth, or the set of teeth may be a part of an
entire set of teeth, thus the set of teeth may also be denoted at
least a part of a set of teeth.
[0133] The expression "positioning relative to" means that either
the virtual alignment plane is fixed in position when seen on e.g.
a graphical user interface, such as a computer screen, and then the
virtual model is moved, or it means that the virtual model is fixed
in position when seen on e.g. the computer screen, and then the
virtual alignment plane is moved. In either way the virtual model
and the virtual alignment plane are seen to virtually move relative
to each other.
[0134] Positioning may be defined as placing, arranging etc.
[0135] Occlusion may be defined as the contacts between the upper
and lower teeth, or as the relationship between the maxillary
(upper) and mandibular (lower) teeth when they approach each other,
as occurs during chewing or at rest.
[0136] In some embodiments the one or more parameters are derived
from a face scan of the patient.
[0137] It is an advantage that the one or more parameters can be
derived from a face scan of the patient, where the movements of the
jaws are scanned when the patient performs e.g. dynamic occlusion,
because this allows for recording of dynamic movements of the jaw
such that dynamic occlusion performed when chewing and open/close
movements can be recorded.
[0138] The face scan can alternatively and/or additionally be used
to measure the static occlusion of the patient.
[0139] These static occlusion and the dynamic occlusion for the
specific patient can then be used when simulating occlusion on the
virtual articulator, and the alignment plane can be positioned
relative to the virtual model of the teeth such that it is a
physiologically correct alignment for that specific patient.
[0140] When the alignment of the teeth in the virtual articulator
is identical to the physiologic alignment in the patient's mouth,
the articulation and occlusion of the virtual articulator will be
physiologic correct, and modelling of restorations can be performed
with an optimal fit and result.
[0141] As an alternative to using a face scanner, other "live"
recording means, such as a CT scan etc. may be used.
[0142] Furthermore, in some embodiments the face scanner is used to
measure features of the face of the patient, such as the facial
midline, the arch midline, the incisal plane, and/or the
interpupillary line.
[0143] Furthermore, in some embodiments the method further
comprises the step of simulating and estimating dynamic occlusal
interferences, wherein said interferences are deduced at least
partly from a plurality of scans that record said patient's jaw
articulation by tracking at least one reference object fixed to the
patient's teeth.
[0144] Yet a further embodiment comprises the step of calculating
the articulation of the jaw and thereby simulating and/or
estimating dynamic occlusal interferences.
[0145] In some embodiments of the invention the face scanner is
used to measure 3D movements of the jaws and face of the patient in
real time.
[0146] In some embodiments of the invention the face scanner is
used to measure the position of the upper jaw and/or lower jaw with
respect to the skull. Thus the face scanner may then replace a
face-bow, which is traditionally used for this static
measurement.
[0147] Thus the face scanner can be used to measure planes of the
face, such as centric determination or the midline, it can be used
to measure jaw movement, and/or it can be used to measure the
attachment and/or movement of the jaws relative to the rest of the
skull.
[0148] Thus the measured jaw motions, which are the physically true
motions or movements, are used to simulate the movement in a
dynamic virtual articulator, such that dental restorations can be
designed, where the dental restorations have improved functionality
and aesthetics. Thus the face scanner can perform the relevant
measurements for providing a dental restoration, and thereby
replacing the use of e.g. face-bows, electronic facebow, use of
standard values or setting etc.
[0149] In a further embodiment of the invention calculation and/or
estimation of the articulation of the jaw and/or the dynamic
occlusal interferences is at least partly based on a plurality of
face scans and at least one 3D model of the pre-prepared and/or
prepared teeth, a 3D model that comprises the antagonist. For
optimal accuracy and precision, it is advantageous to fix one or
more reference spheres or objects to the teeth.
[0150] In some embodiments the movements of the patient's jaws are
scanned in 3D and in real-time using the face scanner.
[0151] It is an advantage that the face scanner scan in real-time,
since real time means that the scanner records movements in real
time, i.e. the scanner records the entire movement as it happens,
such that every step along the movement is recorded. If the face
scanner is not recording in real time the movement itself cannot be
recorded but only some separate points, e.g. extremum points of the
jaws. If a face scanner only takes a scan every minute or the scan
takes a minute to make, that face scanner will not be a real-time
scanner, since the jaw and the face muscles move much faster than
that in true chewing movements. Thus a real-time face scanner will
record gradual movements taking several full 3D frames per second,
as known from a video camera.
[0152] In some embodiments a virtual plane is defined and arranged
relative the virtual articulator.
[0153] In some embodiments the virtual plane is fixed relative to
the virtual articulator.
[0154] In some embodiments the virtual plane is visualised relative
to the upper and lower model.
[0155] In some embodiments the virtual plane is a virtual alignment
plane.
[0156] In some embodiments the virtual alignment plane is fixed
relative to the virtual articulator.
[0157] In some embodiments the
[0158] It is an advantage to arrange a virtual plane or virtual
alignment plane relative to the virtual articulator since this may
improve the alignment of the upper and lower teeth model relative
to each other. It is an advantage that the operator or user may
virtually rotate the models with the plane attached to them, and
that he may zoom in and study details in the alignment of the
models.
[0159] In some embodiments the virtual alignment plane is a default
occlusal plane. It is an advantage because a default occlusal plane
may be defined as a plane passing through the occlusal or biting
surfaces of the teeth. It represents the mean of the curvature of
the occlusal surface. It may be defined at the plane stretched
between three specific teeth as explained above. Furthermore, the
occlusal plane may be defined as an imaginary surface that is
related anatomically to the cranium and that theoretically touches
the incisal edges of the incisors and tips of the occluding
surfaces of the posterior teeth. It represents the mean of the
curvature of the surface. Furthermore, the occlusal plane may be
defined as a line drawn between points representing one half of the
incisal overbite, vertical overlap, in front and one half of the
cusp height of the last molars in back. The occlusal plane may on a
physical, mechanical articulator be marked with a rubber band
placed at specific points relative to the teeth on the model of the
teeth, such that the rubber band indicates a plane.
[0160] In some embodiments the one or more parameters are derived
from a face scanning of the patient, where the movements of the
jaws are scanned when the patient performs dynamic occlusion.
[0161] In some embodiments the movements of the patient's jaws are
scanned in 3D and in real-time using the face scanner.
[0162] In some embodiments one or more of the parameters are
derived from a facebow measurement of the patient.
[0163] It is an advantage to use a facebow to measure the one or
more parameters on a patient. A conventionel facebow is a device
used in dentistry to record static occlusion, e.g. a device to
record the positional relations of the upper arch to the
temporomandibular joints and to orient dental casts in this same
relationship to the opening axis of the articulator. Thus a facebow
may enable gathering of information such that a restoration can be
made to the exact cranium/axis relationship of the patient and
his/her anatomy. By using a mechanical facial bow with electronic
measuring system dynamic occlusion can be measured, and the
measurement data can be transmitted by wire or wirelessly to the
computer, or saved on a memory component. Thus the data from the
electronic facebow measurement can be transferred to the computer
for assisting in placing the alignment plane relative to the
virtual model of the teeth.
[0164] An example of an electronic facebow is a facebow which
enables a precise measurement by means of a number of sensors, such
as sound transmitters and microphones. An electronic facebow can
measure the lower jaw movements in relation to the patient's
cranium. Alternatively, the electronic facebow can be a facebow
using magnetic measurement technology, or the facebow can be a
facebow which uses ultrasound measurement technology, or the
facebow can be any other electronic system transferring the
recorded facebow data to a computer.
[0165] A facebow may be attached to the head of the patient, e.g.
at, above or in the ears, and to the nasal bone between the eyes. A
bite fork with impression material on it may then be placed in the
patient's mouth touching the teeth in the upper arch, and by means
of e.g. ultrasound measurements, the distance between the bite fork
and certain points on the facebow may be determined and/or
movements of the jaws can be measured. The distance can be used to
derive specific anatomical dimensions of the patients face and/or
cranium. Furthermore, another metal fork may then be arranged on
the front surface of the teeth in the lower arch, and the patient
may move his/her lower jaw into different extreme positions, and by
means of e.g. ultrasound measurements, these movements and extreme
positions of the lower jaw relative to the facebow may be measured,
and by these measurements dynamic occlusion and/or specific
anatomical dimensions of the patients face and/or cranium may be
determined.
[0166] All the measurements of static and/or dynamic occlusion with
the facebow as described above may be made and stored
electronically, and the measurements may thus be transferred to a
computer on which the computer-implemented method of placing the
virtual alignment plane relative to the virtual model of the teeth
is performed, and thus the dynamic occlusion measured on the
patient may be used to perform the placement of the virtual
alignment plane relative to the virtual model of the teeth.
[0167] Thus the dynamic occlusion can be recorded electronically
and played or replayed, while modelling e.g. a restoration.
[0168] Furthermore, in some embodiments information about the lower
jaw movements in relation to the upper jaw is transferred from a
facebow and used to define the virtual alignment plane.
[0169] Furthermore, in some embodiments information about the
positional relations of the upper arch to the temporomandibular
joints is transferred from a facebow and used to define the virtual
alignment plane.
[0170] In some embodiments the method further comprises determining
the position and orientation of the facebow relative to the
patient's upper arch.
[0171] In some embodiments the method further comprises determining
the position and orientation of the facebow relative to the
physical articulator.
[0172] In some embodiments the method further comprises determining
the position and orientation of the facebow relative to the virtual
articulator.
[0173] In some embodiments the facebow comprises a bite fork with
impression material for providing an impression of the upper arch
of the teeth, and the method further comprises determining the
position and orientation of the bite fork relative to facebow.
[0174] In some embodiments the method further comprises scanning
the bite fork with the impression of the upper arch teeth to
provide a scan of the impression and a scan of the bite fork.
[0175] A scan of the impression, a scan of the bite fork, and a
scan of both the impression and bite fork can thus be provided.
[0176] It is an advantage to scan the impression on the bite fork
material, since hereby the impression can be used in aligning the
virtual upper and lower jaw and/or aligning plane etc. Thus the
virtual model of the set of teeth can be aligned with the bite fork
and/or the impression in the bite fork by aligning the
depressions/indentations and peaks/top in the model and in the
impression.
[0177] In some embodiments the scan of the impression is aligned
with the virtual model of the set of teeth.
[0178] It is an advantage to align the scan of the impression on
the bite fork relative to the virtual model of the teeth, i.e.
relative to the upper and lower jaw models. The depressions in the
impression material corresponds to the peaks or high points of the
teeth, thus the depressions or low points in the scan of the
impression fit to the corresponding peaks or high points in the
virtual model of the set of teeth.
[0179] In some embodiments the method further comprises determining
the position and the orientation of the bite fork relative to the
virtual articulator.
[0180] Thus the facebow has a coordinate system, CF. This
coordinate system CF is directly transferred to the mechanical
articulator coordinate system CMA when the facebow part with the
bite fork is inserted in the mechanical articulator. The physical
cast models are then attached to the articulator by means of the
facebow information.
[0181] If one wishes to get the position and orientation
information from the facebow coordinate system CF and the bite fork
coordinate system CBF into the virtual articulator coordinate
system CVA, this information should be transformed so that it
becomes digital or can be turned into values to be read off and
typed into the virtual articulator software program.
[0182] The distance between the position of the bite fork relative
to something on the facebow must be determined and made digital to
be transferred into the virtual articulator coordinate system
(CVA).
[0183] When using an electronic facebow, a distance between the
bite fork and a point on the facebow is measured electronically,
and this electronic measurement can be transferred to the computer
and virtual articulator coordinate system CVA.
[0184] The different coordinate systems used may be calibrated with
regard to each other.
[0185] In some embodiments determining the position and the
orientation of the bite fork relative to the virtual articulator
comprises adjusting/fitting the scan of the impression into the
virtual articulator.
[0186] Thus the CAD model or file from scanning of the bite fork
can be used to align the bite fork and the impression on the bite
fork into the virtual articulator.
[0187] In some embodiments determining the position and the
orientation of the bite fork relative to the virtual articulator
comprises reading off values on the facebow and/or bite fork and
typing the values into a user interface for the virtual
articulator.
[0188] In some embodiments determining the position and the
orientation of the bite fork relative to the virtual articulator
comprises electronically transferring data from the facebow and/or
bite fork to the virtual articulator.
[0189] This is possible for example when the facebow is an
electronic facebow.
[0190] In some embodiments determining the position and the
orientation of the bite fork relative to the virtual articulator
comprises:
[0191] arranging the bite fork with the impression in a specific
holder in a 3D scanner; and
[0192] calibrating the position and the orientation of the holder
relative to the virtual articulator.
[0193] This may be advantageous when the bite fork has a fixed or
determined position relative to the facebow, e.g. when the facebow
is an electronic facebow, such that the distance between specific
points on the facebow and on the bite fork are measured
electronically.
[0194] In some embodiments determining the position and the
orientation of the bite fork relative to the virtual articulator
comprises aligning the scan of the bite fork with a CAD model of
the bite fork.
[0195] This may be advantageous when the bite fork has a fixed or
determined position relative to the facebow, e.g. when the facebow
is an electronic facebow, such that the distance between specific
points on the facebow and on the bite fork are measured
electronically.
[0196] The iterative closets point (ICP) method may be used for
aligning, and thus the difference or distance between two point
clouds from scans or models is minimized.
[0197] In some embodiments a transformation between a scan of the
impression and/or a scan of the bite fork and/or a virtual model of
teeth and/or a CAD model in order for arranging them in the same
virtual coordinate system on a user interface is determined through
calibration of the different coordinate systems for the scan(s),
the CAD model(s) and/or the virtual model(s).
[0198] In some embodiments a scan of a physical model of the upper
jaw, a scan of a physical model of the lower jaw and a scan of the
physical models of the two jaws in occlusion are aligned for
deriving occlusion data.
[0199] In some embodiments the positioning of the virtual alignment
plane relative to the virtual model of the set of teeth is
configured to be fine-tuned manually by an operator.
[0200] In some embodiments the positioning of the virtual alignment
plane relative to the virtual model of the set of teeth is
configured to be performed by the operator by selecting one or more
virtual points relative to the virtual model of the set of teeth
within which point(s) the virtual alignment plane should be moved
to.
[0201] Thus it may be a one point alignment, a two point alignment,
a three point alignment etc. One or more of the points may for
example be arranged on posterior molar teeth, such as a first point
arranged on the rearmost tooth in the left side of the mouth and a
second point arranged on the rearmost tooth in the right side of
the mouth. A third point may be arranged in the median line on the
central teeth or on one of the central teeth. Points may be
arranged on the lower and/or upper jaw.
[0202] In some embodiments the one or more parameters are default,
standard parameters.
[0203] In some embodiments the one or more parameters are
patient-specific parameters derived from the specific patient.
[0204] In some embodiments the virtual alignment plane is a default
alignment plane.
[0205] In some embodiments the default alignment plane is
pre-defined and determined based on standard values.
[0206] In some embodiments the virtual alignment plane is a
patient-specific alignment plane, which is determined based on one
or more parameters from the patient.
[0207] In some embodiments the one or more parameters are derived
from the virtual model of the set of teeth.
[0208] Thus dimensions of the arches, jaws, of height differences
between teeth etc may be derived from the model.
[0209] In some embodiments one or more of the parameters are based
on one or more prepared teeth which should be restored.
[0210] In some embodiments one or more of the parameters are the
position of one or more prepared teeth, the labial or buccal
surface direction of the prepared teeth, and/or the upwards or
downwards direction of the prepared teeth.
[0211] In some embodiments one or more of the parameters are based
on the horizontal and/or vertical placement of the one or more
teeth.
[0212] In some embodiments one or more of the parameters are the
position of a number of specific teeth.
[0213] In some embodiments one or more of the parameters are based
on the highest point(s) of the teeth in the lower arch and/or in
the upper arch.
[0214] In some embodiments the one or more parameters is a point on
a molar tooth in the left side of the lower arch, a point on a
molar tooth in the right side of lower arch and a point between the
central teeth in the lower arch. It is an advantage to use these
points as the parameters since they define a plane. The points may
for example be: the distal-buccal cusp of the second molar in both
the left and the right side of the lower arch or jaw, and the point
1 mm below the incisal edge in the space between the two central
teeth in the lower arch or jaw. These points define a plane, which
may be defined the occlusal plane.
[0215] In some embodiments the one or more parameters comprise
measurements of and/or values for the:
[0216] condylar angle;
[0217] Bennett side-shift;
[0218] incisal guidance;
[0219] cuspid guidance;
[0220] shape of the glenoid fossae;
[0221] shape of the eminintiae;
[0222] position of the maxillae duplicated with respect to the
skull; and/or
[0223] face-bow settings.
[0224] It is an advantage to use one or more of these parameters,
since they are the areas where a mechanical articulator and thereby
also the virtual articulator can be adjusted.
[0225] In some embodiments a standard set of teeth is indicated on
the alignment plane for assisting the operator to place the
alignment plane and the virtual model of the teeth correctly
relative to each other.
[0226] In some embodiments means for rotating and translating the
alignment plane and/or the virtual model of the teeth are
provided.
[0227] In some embodiments the means for rotating and translating
are provided as virtual handles.
[0228] In some embodiments the virtual alignment plane and/or the
virtual set of teeth is/are semi-transparent or translucent such
that both the virtual alignment plane and the virtual set of teeth
are visible simultaneously.
[0229] Furthermore, a physical cast model of the upper or lower
teeth may be attached to a certain male plate which fits both in a
corresponding female plate in a 3D scanner and in a corresponding
female plate in a mechanical articulator. Hereby transfer of
positions on the model between the articulator and the scanner is
enabled. The positions determined from this may then be transferred
to the computer software where the virtual articulation and
modelling of restorations are performed. There may also be certain
reference marks on the male plate, on the model etc.
[0230] In some embodiments the virtual model of the set of teeth is
performed by means of intraoral scanning of the teeth or by
scanning an impression of the teeth or by scanning a physical model
of the teeth.
[0231] In some embodiments the method comprises registering the
trace of the collision surface, and automatically cutting away
tooth material based on the collision surface.
[0232] It is an advantage that a virtual cutting away of material
from the modelled teeth can be performed based on the virtual trace
of the simulated collision points surface. Hereby the material need
not be removed virtually afterwards, but is removed on the fly
during the simulation.
[0233] The present invention relates to different aspects including
the method described above and in the following, and corresponding
methods, devices, system, uses and/or product means, each yielding
one or more of the benefits and advantages described in connection
with the first mentioned aspect, and each having one or more
embodiments corresponding to the embodiments described in
connection with the first mentioned aspect and/or disclosed in the
appended claims.
[0234] In particular, disclosed herein is a dynamic virtual
articulator system for simulating occlusion of teeth, when
performing computer-aided designing of one or more dental
restorations for a patient, where the system comprises:
[0235] means for providing the virtual articulator comprising a
virtual three-dimensional model of the upper jaw and a virtual
three-dimensional model of the lower jaw resembling the upper jaw
and lower jaw, respectively, of the patient's mouth;
[0236] means for providing movement of the virtual upper jaw and
the virtual lower jaw relative to each other for simulating dynamic
occlusion, whereby collisions between teeth in the virtual upper
and virtual lower jaw occur;
[0237] wherein the system further comprises:
[0238] means for providing that the teeth in the virtual upper jaw
and virtual lower jaw are blocked from penetrating each other's
virtual surfaces in the collisions.
[0239] Disclosed is furthermore a computer program product
comprising program code means for causing a data processing system
to perform the method when said program code means are executed on
the data processing system; and a computer program product
comprising a computer-readable medium having stored there on the
program code means.
[0240] Disclosed is a computer-implemented method of using a
dynamic virtual articulator for simulating occlusion of teeth, when
performing computer-aided orthodontic treatment planning for a
patient, where the method comprises the steps of:
[0241] providing the virtual articulator comprising a virtual
three-dimensional teeth model comprising the upper jaw, defined as
the virtual upper jaw, and a virtual three-dimensional teeth model
comprising the lower jaw, defined as the virtual lower jaw,
resembling the upper jaw and lower jaw, respectively, of the
patient's mouth;
[0242] providing movement of the virtual upper jaw and the virtual
lower jaw relative to each other for simulating dynamic occlusion,
whereby collisions between teeth in the virtual upper and virtual
lower jaw occur;
[0243] wherein the method further comprises:
[0244] providing that the teeth in the virtual upper jaw and
virtual lower jaw are blocked from penetrating each other's virtual
surfaces in the collisions.
[0245] It is an advantage that the dynamic virtual articulator can
be used for treatment planning in orthodontics, since hereby
dynamic occlusion for orthodontic cases can be simulated.
[0246] In some embodiments treatment planning in orthodontics
comprises segmenting teeth, moving teeth, and/or simulating motion
of jaws and teeths. Thus when using a virtual dynamic articulator
in treatment planning, teeth segmentation may be performed
virtually, teeth movement may be performed virtually, motion
simulation may be performed virtually etc.
[0247] Treatment planning may comprise providing the existing
dental situation for a patient, and providing a desired final
dental situation after orthodontic treatment, and then using the
method of dynamic virtual articulation for testing and simulating
whether the final dental situation is suitable.
[0248] When using the method of dynamic virtual articulation in
restorative dentistry, a part of a modelled tooth which collides
with another tooth can automatically be cut away for avoiding
collisions in the real mouth of the patient during real
articulation, biting, chewing etc.
[0249] However, when using the method of dynamic virtual
articulation in restorative dentistry, no teeth parts should be cut
away, but a tooth colliding with another tooth may be moved,
rotated, turned, etc in a directions so that undesired collision is
avoided in the real bite of the patient.
[0250] In some embodiments the method comprises registering the
trace of collisions, and based on this the orthodontic treatment,
e.g. movement of the different teeth, is planned.
[0251] In some embodiments the method comprises assigning a weight
to one or more teeth.
[0252] In some embodiments the weight assigned to a tooth
determines how susceptible the tooth is to movement.
[0253] In some embodiments a high weight signifies that the tooth
must not be moved, a low weight signifies that it is under all
circumstances allowed to move the tooth, and a medium weight
signifies that it is allowed to move the tooth if suitable for the
treatment.
[0254] It is an advantage to assign different weights to the teeth
to control and guide the treatment, e.g. movement, since some teeth
may have a function or a position already which is important for
e.g. the functionality of the bite, and these teeth should maybe by
no means be moved. Whereas other teeth have no important function
or position, and it may therefore be insignificant for the
functionality or visual aesthetics if those teeth are moved. The
middle group may comprise a number of different weights over a
range, and if two teeth are colliding undesirably during
simulating, then for example the tooth with the lowest weight is
the one which should be moved.
[0255] In some embodiments two or more teeth are locked together,
whereby the two or more teeth are configured to move as an
entity.
[0256] It is an advantage that teeth can be locked together, since
it may be desired that for example the front teeth are not moved
relative to each other.
[0257] In some embodiments the treatment planning and the occlusion
simulation are performed in an iterative manner, whereby each time
a change is made in the treatment plan, the occlusion is
simulated.
[0258] In some embodiments constraints of movement of one or more
teeth are implemented.
[0259] In some embodiments modelling of orthodontic appliances is
configured to be performed.
[0260] In some embodiments the patient's occlusion with the
modelled appliances is configured to be simulated.
[0261] In some embodiments the modelling of the appliances are
performed in an iterative manner, whereby for each change in the
appliances, the occlusion is simulated.
[0262] In some embodiments appliances for the upper jaw and
appliances for the lower jaw are modelled in parallel.
[0263] In some embodiment the appliances are configured to be
braces, brackets, splints, retainers, archwires, aligners, and/or
shells.
[0264] In some embodiments the appliances are configured to retain
teeth in their position.
[0265] In some embodiments the appliances are configured to hinder
the patient from grinding his teeth.
[0266] In some embodiments the appliances are configured to hinder
the patient from snoring in his sleep.
[0267] In some embodiments the appliances are configured to be
comfortable to wear for the patient.
[0268] In some embodiments occlusion of the present set of teeth is
simulated, and the one or more designed appliances is/are
optionally included in the simulation.
[0269] In some embodiments the one or more designed appliances are
modified based on the occlusion simulation.
[0270] In some embodiments the one or more appliances are modified
with respect to position and/or anatomy.
[0271] In some embodiments the virtual articulator is configured to
maintain the upper and lower models in an open position.
[0272] It is an advantage that the teeth models in the virtual
articulator can be held in an open position because for some
orthodontic cases appliances should be designed which keeps the
upper and lower jaw in an open position with a distance to each
other such that the bite can be remodelled. When keeping the models
in an open position in the virtual articulator these appliances for
providing a distance between the teeth can be designed. Thus
appliance which raised and opens the bite can be designed using the
virtual articulator.
[0273] It is a further advantage that a restoration can also be
designed when the virtual articulator is configured with the upper
and lower model in an open position.
[0274] In some embodiments the teeth in the virtual articulator are
color coded for indicating contact between teeth.
[0275] In some embodiments the timewise sequence of events in the
occlusion simulation is registered.
[0276] In some embodiments an occlusal compass is generated based
on the occlusion simulation.
[0277] In some embodiments an occlusal compass generated by real
dynamic occlusion in the patient's mouth is transferred to the
dynamic virtual articulator.
[0278] In some embodiments the occlusal compass indicates movements
in the following directions:
[0279] protrusion;
[0280] retrusion;
[0281] laterotrusion to the right;
[0282] laterotrusion to the left;
[0283] mediotrusion to the right;
[0284] mediotrusion to the left;
[0285] latero-re surtrusion to the right;
[0286] latero-re surtrusion to the left.
[0287] In some embodiments the occlusal compass indicates the
different movement directions with different colors on the
teeth.
[0288] An occlusal compass for a cusp is a three-dimensional
pattern, which is a summation of a cusp's movement in all three
planes of motion. The occlusal compass has elevations and
depressions, and for any given cusp it may vary from that of any
other cusp as a function of its relationship to the mandibular
rotation centers. It is thus an advantage to use occlusal
compasses, since there is not one type of occlusal morphology
suitable for every patient. Thus using occlusal compasses,
morphology and functional restorations may be designed to fit the
specific patient.
[0289] In some embodiments the occlusal contact forces in one or
more parts on the teeth is registered.
[0290] In some embodiments the occlusal contact forces over time in
one or more parts of the teeth are registered.
[0291] In some embodiments the occlusal contact forces are
registered by means of an electronic sensor for measuring the
occlusal contact forces.
[0292] In some embodiments the registered occlusal contact forces
are transferred to the dynamic virtual articulator.
[0293] It is an advantage to use an electronic sensor for measuring
the occlusal contact forces, e.g. a T-Scan III (R) from Tekscan,
since hereby the occlusal contact forces can be determined in the
mouth of the patient and transferred electronically to the dynamic
virtual articulator for use in the simulation of dynamic occlusion.
The dynamic virtual articulation and simulation of the patient's
bite may be enhanced using the occlusal contact force
measurement.
[0294] In some embodiments the force of occlusion is simulated.
[0295] The simulation is performed in the software, using e.g. the
virtual articulator.
[0296] In some embodiments the registered and/or simulated force of
occlusion is visualized.
[0297] In some embodiments a biophysical model of the functionality
of the jaws and the force of the occlusion is generated.
[0298] In some embodiments data from a force measurement is
recorded by means of an electronic component in the patient's
mouth.
[0299] In some embodiments the date from the force measurement is
transferred into and overlaid in the dynamic virtual
articulator.
[0300] In some embodiments a CT scan of the patient's mouth is
generated, and a virtual 3D model of the patient's mouth is
automatically generated based on the scan, and occlusion is
configured to be simulated based on the 3D CT model.
[0301] In some embodiments the positions and/or sizes of the jaw
muscles are derived from the CT scan, and based on the muscles the
strength of the occlusion is configured to be simulated.
[0302] In some embodiments a CT scan of at least part of the
patient's skull is transferred into the virtual articulator.
[0303] In some embodiments constraints to the simulation of the
occlusion are derived from the CT scan.
[0304] In some embodiments one or more tooth roots are visual on
the CT scan, and the position of the tooth roots are used to
simulate movement of teeth.
[0305] In some embodiments a 2D image of the patient is transferred
into the virtual articulator.
[0306] In some embodiments a weight assigned to a tooth determines
its functionality importance in guiding the occlusion of the
patient.
[0307] In some embodiments a high weight signifies that the tooth
is important for guiding the occlusion.
[0308] In some embodiments a low weight signifies that the tooth is
not important for guiding the occlusion.
[0309] In some embodiments a medium weight signifies that tooth's
importance for guiding the occlusion is medium.
[0310] In some embodiments the central teeth and/or the canines
is/are assigned a high weight.
[0311] It is an advantage to assign a high weight to the centrals
and/or to the canines in the upper and/or lower jaw, since these
teeth often are the most important teeth for guiding the occlusion,
since they are the longest teeth. Thus if these teeth are important
for guiding the occlusion, they should preferably not be moved,
shortened, removed, restored etc, since this could influence the
occlusion negatively.
[0312] In some embodiments occlusion of the present set of teeth is
simulated, and the one or more designed restorations is/are
optionally included in the simulation.
[0313] In some embodiments the one or more designed restorations
are modified based on the occlusion simulation.
[0314] In some embodiments the one or more restorations are
modified with respect to position and/or anatomy.
[0315] In some embodiments the virtual articulator is used for
simulating occlusion when designing a partial removable prosthesis
for a patient.
[0316] It is a problem if a restoration becomes too high, such as
extending a little above the neighbour teeth, because then it may
interrupt the patient's bite and/or easily become broken. Thus it
is desired that the restoration on the prepared tooth in the
patient's mouth is lower or shorter than the neighbour teeth.
[0317] Traditionally, when performing manual modelling of
restorations, the dental technician would manually push the
prepared tooth a little bit up in the cast model and then make the
restoration.
[0318] When performing virtual design or modelling of a restoration
in software, traditionally the virtual lower model and the virtual
upper model will be virtually moved such that they have an overlap,
and the restoration is then designed. This is done because the
models are virtual models and therefore can penetrate each other in
the virtual 3D space in traditional software modeling.
[0319] In some embodiments a prepared tooth in the virtual 3D model
is displaced to be arranged with a distance from its actual
position relative to its neighbour teeth and/or its position in the
gingival before designing the restoration for the prepared
tooth.
[0320] It is an advantage because when a restoration is designed on
the displaced prepared tooth, the restoration can be designed to be
level with the neighbour teeth, and when the prepared tooth with
restoration is again arranged in its actual position in the virtual
3D model, the restoration will be lower or shorter than the
neighbour teeth, and the real restoration on the real prepared
tooth in the patient's mouth will therefore also be lower or
shorter than the real neighbour teeth and hereby the restoration,
which may be more fragile than the real teeth, may be better
protected against collisions in the mouth with other teeth or food
stuff etc. The distance the prepared tooth is displaced may be in
the range of millimetres, micrometers etc. The distance may be a
vertical distance.
[0321] According to the present embodiment, the virtual modelling
is performed in a way similar to the traditional manual work, since
the prepared tooth is displaced instead of moving models to be
overlapping.
[0322] It is an advantage that the restoration can be designed to
have an interocclusal distance, such as an extended interocclusal
distance instead of being designed to be in contact. The
interocclusal distance is defined as the distance between the
occlusal surfaces of the teeth in the lower and upper mouth, and
thus in this connection the interocclusal distance may be defined
as the distance between the restoration and the antagonist
teeth.
[0323] In some embodiments a gingival part in a position of a
missing tooth in the virtual 3D model is displaced to be arranged
with a distance from its actual position before designing an
implant restoration or a pontic in a bridge for the position of the
missing tooth.
[0324] It is an advantage that the implant, implant crown, pontic
etc. is lower than the neighbour teeth for protecting the implant
restoration, the pontic restoration etc against collisions etc.
[0325] In some embodiments one or more contact criteria for
occlusion is defined and used in simulation of occlusion.
[0326] In some embodiments the one or more contact criteria
comprises:
[0327] specific teeth must be in contact with each other;
[0328] a maximum number of teeth must be in contact;
[0329] a maximum area of the teeth surfaces must be in contact;
[0330] specific teeth must not be in contact;
[0331] a maximum number of contact points must be obtained;
[0332] contact points must be evenly spatially distributed over the
surface of teeth; and/or
[0333] the contact points between teeth must not be disclosed more
than a certain distance during certain dynamic occlusion
movements.
[0334] The contact criteria may be used to estimate, correct,
and/or improve the virtual articulator model, e.g. the geometrical
and/or physiological model of the virtual articulator.
[0335] Parameters of the virtual articulator model may be
automatically optimised, adjusted, corrected, defined, determined
etc. by simulating the movement of the jaws in the articulator, and
the simulation may be based on the virtual articulator model.
[0336] For example the operator may often wish to optimise the
condyle inclination, since this an important parameter for many
cases.
[0337] By improving the occlusion by means of parameters and
contact criteria, the quality of the occlusion will be improved in
relation to the patient's real, physiologic occlusion.
[0338] For example if there are mistakes or faults in the data of
the patient's occlusion taken from the mechanical articulator, the
facebow etc, then the occlusion can be corrected using parameters
and contact criteria.
[0339] Disclosed is also a system for using a dynamic virtual
articulator for simulating occlusion of teeth, when performing
computer-aided designing of one or more dental restorations for a
patient, where the system comprises:
[0340] means for providing the virtual articulator comprising a
virtual three-dimensional teeth model comprising the upper jaw,
defined as the virtual upper jaw, and a virtual three-dimensional
teeth model comprising the lower jaw, defined as the virtual lower
jaw, resembling the upper jaw and lower jaw, respectively, of the
patient's mouth;
[0341] means for providing movement of the virtual upper jaw and
the virtual lower jaw relative to each other for simulating dynamic
occlusion, whereby collisions between teeth in the virtual upper
and virtual lower jaw occur;
[0342] wherein the system further comprises:
[0343] means for providing that the teeth in the virtual upper jaw
and virtual lower jaw are blocked from penetrating each other's
virtual surfaces in the collisions.
[0344] Disclosed is also a system for using a dynamic virtual
articulator for simulating occlusion of teeth, when performing
computer-aided orthodontic treatment planning for a patient, where
the system comprises:
[0345] means for providing the virtual articulator comprising a
virtual three-dimensional teeth model comprising the upper jaw,
defined as the virtual upper jaw, and a virtual three-dimensional
teeth model comprising the lower jaw, defined as the virtual lower
jaw, resembling the upper jaw and lower jaw, respectively, of the
patient's mouth;
[0346] means for providing movement of the virtual upper jaw and
the virtual lower jaw relative to each other for simulating dynamic
occlusion, whereby collisions between teeth in the virtual upper
and virtual lower jaw occur;
[0347] wherein the system further comprises:
[0348] means for providing that the teeth in the virtual upper jaw
and virtual lower jaw are blocked from penetrating each other's
virtual surfaces in the collisions.
[0349] Disclosed is also a dental restoration designed according to
the present method.
[0350] Disclosed is also an orthodontic appliance for use in an
orthodontic treatment planning, where the appliance is designed
according to the present method.
BRIEF DESCRIPTION OF THE DRAWINGS
[0351] The above and/or additional objects, features and advantages
of the present invention, will be further elucidated by the
following illustrative and non-limiting detailed description of
embodiments of the present invention, with reference to the
appended drawings, wherein:
[0352] FIG. 1 shows an example of a flow chart of the method.
[0353] FIG. 2 shows examples virtual articulators.
[0354] FIG. 3 shows an example of movements of the jaws for
simulating occlusion.
[0355] FIG. 4 shows an example of modelling of a restored
tooth.
[0356] FIG. 5 shows a schematic example of movement along the
occlusial axis.
[0357] FIG. 6 shows an example of a virtual model of a set of
teeth.
[0358] FIG. 7 shows an example of a virtual occlusal plane.
[0359] FIG. 8 shows a first example of a virtual occlusal plane and
a virtual model before they are adjusted relative to each other's
positions.
[0360] FIG. 9 shows a second example of a virtual occlusal plane
and a virtual model while they are adjusted relative to each
other's positions.
[0361] FIG. 10 shows an example of a virtual occlusal plane and a
virtual model after they are adjusted relative to each other's
positions.
[0362] FIG. 11 shows an example of a virtual articulator.
[0363] FIG. 12 shows an example of a flow chart of an embodiment of
the invention.
[0364] FIG. 13 shows an example of a movement of the virtual upper
jaw and the virtual lower jaw relative to each other.
[0365] FIG. 14 shows an example of displacing the position of a
prepared tooth for designing the restoration.
[0366] FIG. 15 shows an example of displacing the position of a
gingival part for designing the restoration.
[0367] FIG. 16 shows an example of an occlusal compass.
[0368] FIG. 17 shows an example of playing a recording of the jaw
movements.
[0369] FIG. 18 shows an example of modeling a restoration to
compensate for collisions with the opposite teeth.
[0370] FIG. 19 shows examples of virtual articulators resembling
physical articulators form different manufacturers.
[0371] FIG. 20 shows an example of a virtual articulator, which
only exists as a virtual articulator.
[0372] FIG. 21 shows examples of the traces of movement.
[0373] FIG. 22 shows an example of virtual simulation of
orthodontic treatment planning.
[0374] FIG. 23 shows an example of virtual simulation of dental
displacement.
[0375] FIG. 24 shows an example of an orthodontic appliance for
displacing teeth.
DETAILED DESCRIPTION
[0376] In the following description, reference is made to the
accompanying figures, which show by way of illustration how the
invention may be practiced.
[0377] FIG. 1 shows an example of a flow chart showing the steps of
the computer-implemented method of using a dynamic virtual
articulator for simulating occlusion of teeth, when performing
computer-aided design of one or more dental restorations for a
patient.
[0378] In step 101 the virtual articulator comprising a virtual
three-dimensional model of the upper jaw and a virtual
three-dimensional model of the lower jaw resembling the upper jaw
and lower jaw, respectively, of the patient's mouth is
provided.
[0379] In step 102 movement of the virtual upper jaw and the
virtual lower jaw relative to each other is provided for simulating
dynamic occlusion, whereby collisions between teeth in the virtual
upper and virtual lower jaw occur;
[0380] In step 103 the teeth in the virtual upper jaw and virtual
lower jaw are provided to be blocked from penetrating each other's
virtual surfaces in the collisions.
[0381] FIG. 2 shows examples virtual articulators.
[0382] FIG. 2a) shows a virtual upper jaw 204 with teeth 206 and a
virtual lower jaw 205 with teeth 206. Six teeth 207 in the upper
jaw 204 have been restored, and the virtual articulator 208 are
used to simulate the movements of the jaws 204, 205 to test if the
restored teeth 207 fit into the mouth of a patient. The virtual
articulator 208 is indicated by two axes, an occlusial axis 209 and
a laterotrusial-mediotrusial axis 210. The jaws 204, 205 moves up
and down along the occlusial axis 209, and the jaws 204, 205
performs forward-sidewards movements to both left and right along
the laterotrusial-mediotrusial axis 210. The jaws 204, 205 can also
perform protrusion, which is direct forward movement, and
retrusion, which is direct backward movement. The axes for these
movements are not shown in the figure.
[0383] In the figure only movement along the occlusial axis 209 is
shown, while there is no movement along the
laterotrusial-mediotrusial axis 210 or along the
protrusial-retrusial axes (not shown). This is also seen in the
window 211 in the upper left of the figure, where the parameter
"occlusion" is 6.60 and the parameter "laterotrusion" is 0.00, and
the parameter "pro-/retrusion" is also 0.00. The different movement
directions possible may be:
[0384] protrusion;
[0385] retrusion;
[0386] laterotrusion to the right;
[0387] laterotrusion to the left;
[0388] mediotrusion to the right;
[0389] mediotrusion to the left;
[0390] latero-re surtrusion to the right;
[0391] latero-re surtrusion to the left.
[0392] FIG. 2b) shows another virtual articulator 208 with setting
opportunities 209, 210 for controlling the movement of the jaws
204, 205 along an occlusial axis, a laterotrusial-mediotrusial
axis, a protrusial-retrusial axis etc. The indentations 240
indicate where the dental technician will arrange a default
occlusal plane in the form of a rubber band.
[0393] FIG. 3 shows an example of movements of the jaws for
simulating occlusion.
[0394] Both jaws 204, 205 comprise non-modified teeth 206, and the
upper jaw 204 also comprises restored teeth 207. The movements are
made to simulate, if the restored teeth 207 fit into the mouth.
[0395] FIG. 3a) shows the jaws 204, 205 in a first position, where
no teeth 206 in the jaws 204, 205 have collided with the restored
teeth 207.
[0396] FIG. 3b) shows the jaw 204, 205 in a second position, where
the jaw 204, 205 have moved closer to each other, but there is
still no collision between any of the teeth 206 or the restored
teeth 207.
[0397] FIG. 3c) shows the jaws 204, 205 in a third position, where
the jaw 204, 205 have moved even closer to each other.
[0398] FIG. 3d) shows the jaws 204, 205 in the third position with
a circle 212 at a point 213, where the teeth of the jaws 204, 205
have collided. The collision is between a restored tooth 207a in
the upper jaw 204 and a tooth 206a in the lower jaw 205.
[0399] FIG. 4 shows an example of modelling of a restored
tooth.
[0400] FIG. 4a) shows the upper jaw 204, turned around relative to
the preceding figures, with the restored tooth 207a, another
restored tooth 207 and an un-modified tooth 206. The restored tooth
207a has collided with a tooth in the lower jaw, as shown in FIG.
3d), and the collision points 214 are indicated on the tooth 207a.
The shades of the collision points may indicate the penetration
depth or the pressure with which the tooth 207a and the tooth in
the lower jaw collided. Thus the shades from light to dark indicate
a depth mapping or pressure mapping, where light shade indicates
low depth or light pressure and dark shade indicates large depth or
hard pressure.
[0401] It may be so that the teeth are not completely rigid, but
are a little bit soft, and the teeth may therefore give or deform a
little when colliding with each other. Thus it may be so that the
virtual teeth are not defined to be completely rigid, but are a
little bit soft or resilient, and the virtual teeth may therefore
give or deform a little when virtually colliding with each
other.
[0402] FIG. 4b) shows the same as FIG. 4a) and also tools for
modelling the restored tooth 207a. Since the tooth 207a collided
with a tooth in the lower jaw, see FIG. 3d), the restored 207a) can
be modelled such that it will not collide with the tooth in the
lower jaw. The tooth 207a can be modelled by dragging or morphing
it to the left or right side indicated by the tools 215, and by
dragging the tooth 207a up and down indicated by the tool 216. The
tooth 207a can also be modelled by dragging or morphing points on
it to the left side or right side indicated by tools 217, and by
dragging or morphing it to the neighbour teeth indicated by tools
218.
[0403] While morphing or dragging the tooth 207a, the collision
points 214 will change corresponding to these shape changes of the
tooth, and the tooth 207a can then be modelled such that there will
no longer be any collision with the teeth in the lower jaw, and the
collisions points 214 will then disappear from the tooth 207a
indicating that the tooth 207a has been modelled to avoid
collisions with opposing teeth.
[0404] FIG. 5 shows a schematic example of movement along the
occlusial axis.
[0405] The figure shows the upper jaw 204 with teeth 206 and the
lower jaw 205 with teeth 206. Some of these teeth may be restored
teeth, and therefore the occlusion may be tested.
[0406] The occlusial axis 209 is indicated, and the upper jaw 204
is shown to be fixed to the occlusial axis. The lower jaw 205 can
move relative to the upper jaw 204 and therefore the lower jaw can
rotate around the occlusial axis 209. Thus the virtual articulator
performs collision test and evaluate the response along the
occlusial axis 209, i.e. for any given configuration of the other
degrees of freedom, i.e. the other axes, see FIG. 2, and thereby
finding the first position on the occlusial axis for which the two
jaw models are in contact. This reduces the dimensionality of the
calculation problem and allows for the use of more specialized
search structures, which are aimed at calculating the first point
of intersection with a 3D model along a given circular path 219
around the static rotation axis 209 of occlusion. Thus for each
motion step along one of the other axes, i.e. for each degrees of
freedom, it may be calculated when and at which points the teeth
206 in the jaws 204, 205 will collide along the occlusial axis
209.
[0407] FIG. 6 shows an example of a virtual model of a set of
teeth.
[0408] The virtual model 601 of the set of teeth from a patient
comprises a virtual lower arch 602 and a virtual upper arch/jaw
603. Six front teeth 604 in the upper arch 603 are marked in a
different color than the rest of the teeth 605 of the set of teeth.
These six teeth 604 may be teeth which should be or have been
restored. The virtual model 601 may be shown in a graphical user
interface, in which an operator, such as a dental technician or
dentist, can design, simulate and/or model for example restorations
for a patient.
[0409] FIG. 7 shows an example of a virtual occlusal plane.
[0410] The occlusal plane 706 is visualized as a flat, circular
plane, but it is understood that the occlusal plane can have any
shape etc. The occlusal plane is a plane passing through the
occlusal or biting surfaces of the teeth, and it represents the
mean of the curvature of the occlusal surface. Thus the the
occlusal plane can be flat or undulating following the different
heights of the different teeth.
[0411] A contour of a standard set of teeth 707 is shown on the
occlusal plane 706 for assisting the operator to better match the
3D position of the occlusal surface 706 with a virtual model.
[0412] A virtual articulator 708 is indicated by two axes, an
occlusial axis 709 and a laterotrusial-mediotrusial axis 710. The
upper and lower arches of the virtual model can move up and down
along the occlusial axis 709, and the arches can perform
forward-sidewards movements to both left and right along the
laterotrusial-mediotrusial axis 710. The arches can also perform
protrusion, which is direct forward movement, and retrusion, which
is direct backward movement. The axes for these movements are not
shown in the figure.
[0413] The different movement directions possible may be:
[0414] protrusion;
[0415] retrusion;
[0416] laterotrusion to the right;
[0417] laterotrusion to the left;
[0418] mediotrusion to the right;
[0419] mediotrusion to the left;
[0420] latero-re surtrusion to the right;
[0421] latero-re surtrusion to the left.
[0422] FIG. 8 shows a first example of a virtual occlusal plane and
a virtual model before they are adjusted relative to each other's
positions.
[0423] The occlusal plane 806 with the standard set of teeth 807
and the virtual model of the lower arch 802 are shown together. The
occlusal plane 806 is shown to be inclined relative to the virtual
model of the lower arch 802, and the occlusal plane 806 and the
virtual model of the lower arch 802 are intersecting each other as
seen by the intersection line 811.
[0424] FIG. 9 shows a second example of a virtual occlusal plane
and a virtual model while they are adjusted relative to each
other's positions.
[0425] The occlusal plane 906 with the standard set of teeth 907
and the virtual model of the lower arch 902 are shown together. The
occlusal plane 906 and the virtual model of the lower arch 902 are
nearly aligned as their inclinations are the same or almost the
same, but the occlusal plane 906 and the virtual model of the lower
arch 902 are still intersecting each other a little bit as seen by
the intersection line 911 because some of the teeth of the lower
arch 902 are a little bit higher than the vertical position of the
occlusal plane 906. The occlusal plane 906 and the lower arch 902
are not aligned horizontally yet, because the standard set of teeth
907 on the occlusal plane 906 are not overlapping with the teeth of
the lower arch 902.
[0426] FIG. 10 shows an example of a virtual occlusal plane and a
virtual model after they are adjusted relative to each other's
positions.
[0427] The occlusal plane 1006 with the standard set of teeth 1007
and the virtual model of the lower arch 1002 are shown together.
The occlusal plane 1006 and the virtual model of the lower arch
1002 are aligned as their inclinations are the same, and the
occlusal plane 1006 and the virtual model of the lower arch 1002
are still intersecting each other a little bit as seen by the
intersection line 1011 because some of the teeth of the lower arch
1002 are a little bit higher than the vertical position of the
occlusal plane 1006. The occlusal plane 1006 and the lower arch
1002 are aligned horizontally, because the standard set of teeth
1007 on the occlusal plane 1006 are overlapping with the teeth of
the lower arch 1002. The alignment may be a 3-point alignment, i.e.
using three points for performed the alignment.
[0428] FIG. 11 shows an example of a virtual articulator.
[0429] The virtual articulator 1108 is a virtual version of a
physical, mechanical device used in dentistry to which casts of the
upper and lower teeth are fixed and reproduces recorded positions
of the lower teeth in relation to the upper teeth. An articulator
can be adjustable in one or more of the following areas: condylar
angle, Bennett side-shift, incisal and cuspid guidance, and shape
of the glenoid fossae and eminintiae. An articulator may reproduce
normal lower movements during chewing. An articulator may be
adjusted to accommodate the many movements and positions of the
lower teeth in relation to the upper teeth as recorded in the
mouth. Thus the virtual articulator may perform all the movements
etc. as the mechanical articulator.
[0430] The virtual articulator 1108 comprises a bottom base 1109
onto which the virtual model of the lower teeth or lower jaw is
adapted to be arranged, a top base 1110 onto which the virtual
model of the upper teeth or upper jaw is adapted to be arranged.
The different virtual joints, slides or setting means 1111
indicates the joints, slides and other settings of a mechanical
articulator where the different areas mentioned above can be
adjusted to the features of a specific patient.
[0431] FIG. 12 shows an example of a flow chart of an embodiment of
the invention.
[0432] In step 1201 the movement of the virtual upper jaw and the
virtual lower jaw relative to each other is started.
[0433] In step 1202 all collisions during the movement of the
virtual upper jaw and the virtual lower jaw relative to each other
are registered.
[0434] In step 1203 the movement of the virtual upper jaw and the
virtual lower jaw relative to each other is finished.
[0435] In step 1204 each area of the restorations where a collision
point was registered is modelled.
[0436] FIG. 13 shows an example of a movement of the virtual upper
jaw and the virtual lower jaw relative to each other.
[0437] FIG. 13a) shows the first position of a movement between the
upper jaw 1304 and the lower jaw 1305. Both the lower jaw and the
upper jaw comprise teeth 1306, and the upper jaw comprises a number
of restorations 1307.
[0438] FIG. 13b) shows a position during the movement of the jaws.
The upper jaw 1304 is moved relative to the lower jaw 1305, and the
restoration 1307 is colliding with a tooth 1306 as seen by the
collision point 1314 comprising a contact area.
[0439] FIG. 13c) shows the end position of the movement of the
jaws, and all the collision points are marked on the teeth and
restorations. The restoration 1307 can now be modelled by virtually
removing or remodelling material from the restoration, whereby the
collision in point 1314 will not happen again when the jaws are
moved relative to each other, both virtually and in the patient's
mouth.
[0440] FIG. 14 shows an example of displacing the position of a
prepared tooth for designing the restoration.
[0441] FIG. 14a) shows an example of a 3D representation of a set
of teeth 1400, where a tooth 1401 has been prepared for a
restoration, such as a crown. Two neighbour teeth 1402 are also
shown. The toot roots 1403 are indicated. The tooth roots 1403 may
be derived from a CT scan or may be extrapolated based in a normal
3D scan. Showing the tooth roots 1403 in the 3D representation is
optional, since designing a restoration does not require seeing the
tooth root, but it may a help for the operator designing the
restoration. The gingival 1404 is also seen.
[0442] FIG. 14b) shows that the preparation 1401 is vertically
displaced from its position at the gingival 1404 and from the
neighbour teeth to reduce the distance to the antagonist when
designing the restoration.
[0443] FIG. 14c) shows that a restoration 1405, here in the form of
a crown, is designed on the preparation, when the preparation is
displaced from the gingival 1404 and the neighbour teeth. Thus the
restoration is designed in a different occlusion than the normal
occlusion of the teeth. The upper edge of the restoration 1405 is
shown to be substantially flush or level with the two neighbour
teeth 1402 when being designed.
[0444] FIG. 14d) shows the situation when the preparation 1401 with
the restoration 1405 is positioned in its actual position again
after designing the restoration 1405. Because the restoration 1405
was designed to be level with the neighbour teeth 1402 when it was
displaced, the restoration 1405 is shorter than the neighbour teeth
1402, when it is positioned in its original position again. Thus in
the mouth of the patient, the restoration will be shorter than the
neighbour teeth, and the restoration, which may be more fragile
than the real teeth, is therefore protected better.
[0445] FIG. 15 shows an example of displacing the position of a
gingival part for designing the restoration.
[0446] FIG. 15a) shows an example of a 3D representation of a set
of teeth 1500 with a missing tooth in a region of the gingival
1506. The missing tooth may have been broken, died, pulled out due
to disease etc. A restoration should be made to replace the missing
tooth in the region 1506. Two neighbour teeth 1502 are also shown.
The toot roots 1503 are indicated. The tooth roots 1503 may be
derived from a CT scan or may be extrapolated based in a normal 3D
scan. Showing the tooth roots 1503 in the 3D representation is
optional, since designing a restoration does not require seeing the
tooth root, but it may a help for the operator designing the
restoration. The gingival 1504 is also seen.
[0447] The restoration to made to replace the missing tooth may be
a bridge. The bridge may comprise a pontic in the place of the
missing tooth and two crowns on the neighbour teeth 1502.
[0448] FIG. 15b) shows that the two neighbour teeth have been
prepared and are now prepared teeth 1501. The region of the
gingival 1506 of the missing tooth is displaced from its original
position at the gingival.
[0449] FIG. 15c) shows that a restoration, here in the form of a
bridge, is designed. A pontic 1507 is arranged in the place of the
missing tooth, and crowns 1505 have been designed on the two
preparations 1501. The pontic is attached to the crowns. The pontic
1507 is designed, when the region of the gingival 1506 is displaced
from its original position. The upper edge of the pontic 1507 is
substantially flush or level with the designed crowns 1505 on the
two prepared neighbour teeth 1501.
[0450] FIG. 15d) shows the situation when the pontic 1507 and the
region of the gingival 1506 is positioned in its actual position
again after designing the pontic 1507. Because the pontic 1507 was
designed to be level with the crowns 1505 of the neighbour teeth,
when it was displaced, the pontic 1507 is shorter than the crowns
1505 neighbour teeth, when the pontic 1507 is positioned in its
original position again. Thus in the mouth of the patient, the
pontic will be shorter than the crowns of the neighbour teeth, and
the pontic, which may be more fragile than the crowns of the
neighbour teeth, is therefore protected better.
[0451] FIG. 16 shows an example of an occlusal compass.
[0452] The occlusal compass indicates movements during dynamic
occlusion in the following directions:
[0453] protrusion;
[0454] retrusion;
[0455] laterotrusion to the right;
[0456] laterotrusion to the left;
[0457] mediotrusion to the right;
[0458] mediotrusion to the left;
[0459] latero-re surtrusion to the right;
[0460] latero-re surtrusion to the left.
[0461] The occlusal compass indicates the contact or collision in
different movement directions with different colors. The colors may
be according to the international colouring scheme. The occlusal
compass used in the virtual simulation is a unique digital
tool.
[0462] FIG. 17 shows an example of playing a recording of the jaw
movements. The movement of the virtual upper jaw and the virtual
lower jaw relative to each other has been recorded, and before
and/or after modeling a restoration, the recording can be played to
test the modeling. A predefined motion sequence may also be
played.
[0463] FIG. 18 shows an example of modeling a restoration to
compensate for collisions with the opposite teeth.
[0464] During the movement of the virtual upper jaw and the virtual
lower jaw relative to each other the collisions, marked with on the
restoration, occlusion between teeth are registered, and after the
movement is finished, modeling of the collision points of the
restoration is performed.
[0465] FIG. 19 shows examples of virtual articulators resembling
physical articulators form different manufacturers.
[0466] FIG. 19a) shows an articulator from KaVo.
[0467] FIG. 19b) shows an articulator from SAM.
[0468] FIG. 19c) shows an articulator from Denar.
[0469] FIG. 19d) shows the articulator from Denar with the occlusal
plane arranged relative to the virtual teeth model.
[0470] FIG. 20 shows an example of a virtual articulator, which
only exists as a virtual articulator.
[0471] FIG. 20a) shows a 3Shape virtual articulator. The
articulator does not exist as a physical articulator.
[0472] FIG. 20b) shows the 3Shape virtual articulator with the
occlusal plane arranged relative to the virtual teeth model.
[0473] FIG. 21 shows examples of the traces of movement.
[0474] FIG. 21a) shows an example of a first collision point 2114
between an unmodified tooth 2106 and another unmodified tooth or
restoration 2107 at time t1.
[0475] FIG. 21b) shows an example of a subsequent collision point
2114 between the unmodified tooth 2106 and the other unmodified
tooth or restoration 2107 at time t2.
[0476] FIG. 21c) shows an example of another subsequent collision
point 2114 between the unmodified tooth 2106 and the other
unmodified tooth or restoration 2107 at time t3.
[0477] FIG. 21d) shows the trace of the motion for the other
unmodified tooth or restoration 2107 and the tooth 2106 at the
three time instances, t1, t2, t3.
[0478] The trace of the motion between the tooth 2106 and the other
unmodified tooth or restoration 2107 is indicated by the arrows
2120. The surface of collision points 2114 may be denoted the trace
motion, the motion trace surface etc.
[0479] Thus when unmodified teeth are simulated relative to each
other, their motion traces or their surfaces cannot penetrate each
other. The same may be the case for a restoration relative to an
unmodified tooth.
[0480] However, it may alternatively be the case that when a
restoration and an unmodified tooth are simulated relative to each
other, the motion surface of the restoration may penetrate the
unmodified tooth.
[0481] Thus the term collision surface or trace of collisions
points or collision points surface is used for both describing when
unmodified teeth are simulated to move relative to each where the
teeth collide and do not penetrate each other and for describing
when a restoration is simulated relative to unmodified teeth where
the restoration may penetrate the unmodified teeth, i.e. the
restoration and the unmodified may penetrate each other.
[0482] The simulated collisions or collision surfaces between
unmodified teeth may determine the motion which can be performed
between the upper and lower teeth models.
[0483] This determined motion may then be used and studied when
designing the restoration.
[0484] FIG. 21e) shows the trace 2120 of a motion for a restoration
2107 and a tooth 2106 at the four time instances, t1, t2, t3, t4.
The motion is shown at the three time instances t1, t2, t3, t4 and
time instance lying in between and before and after.
[0485] In FIG. 21e) the restoration 2107 and the tooth 2106 are
shown to penetrate each other in the motion.
[0486] The surface of collision or penetration points may be
denoted the trace motion 2120.
[0487] The tooth 2106 is shown to move relative to the restoration
2107, however it may be vice versa, i.e. that the restoration 2107
moves relative to the tooth 2107.
[0488] FIG. 22 shows an example of virtual simulation of
orthodontic treatment planning.
[0489] FIG. 22a) shows a virtual orthodontic model of teeth with an
upper model 2204 and a lower model 2205 in a virtual articulator
2208 for simulating the occlusion. The simulation of occlusion in
the virtual articulator can detect and study malocclusion, and
assist and/or determine an orthodontic treatment planning. An
orthodontic treatment can also be performed for pure cosmetic
reasons, if the patient's teeth are arranged aesthetically.
[0490] FIG. 22b) shows a zoom-in on the teeth in the virtual models
2204, 2205, where contact areas or collision points 2214 are
registered during simulation of the occlusion. The detected contact
areas or collision points 2214 can be used in determining the
treatment planning to be performed.
[0491] FIG. 23 shows an example of virtual simulation of dental
displacement.
[0492] FIG. 23a) shows a virtual upper teeth model 2304 of a
patient's teeth before orthodontic treatment, where the teeth 2307
are not arranged aesthetically.
[0493] The contact areas or collision point 2314 detected or
registered in a virtual articulator simulation are shown on the
teeth.
[0494] FIG. 23b) shows an example of the virtual upper teeth model
2304 with a suggested final result which can be obtained after
displacement of the teeth 2307.
[0495] Based on the image in FIG. 23b) a patient can decide whether
he wish to have the dental displacement performed for obtaining the
aesthetic set of front teeth.
[0496] FIG. 24 shows an example of an orthodontic appliance for
displacing teeth.
[0497] FIG. 24a) shows a virtual upper model 2404 and a virtual
lower model 2405, where a virtual orthodontic appliance 2430 in the
form of a splint is shown to be arranged in the teeth in the upper
model 2404. The physical appliance may be worn by a patient on his
teeth for treating temporal mandibular dysfunction. The appliance
2430 may be virtually designed using a virtual articulator, e.g. as
shown in FIG. 22a).
[0498] FIG. 24b) shows a top view of the appliance 2430 on the
virtual teeth model 2404.
[0499] FIG. 24c) shows a perspective side view of the appliance
2430 on the virtual teeth model 2404.
[0500] FIG. 24d) shows a bottom view of the appliance 2430.
[0501] The appliance design in FIGS. 24 are the courtesy of and
kindly provided by Tridentestense Ortodonzia S.r.I, Italy.
[0502] Although some embodiments have been described and shown in
detail, the invention is not restricted to them, but may also be
embodied in other ways within the scope of the subject matter
defined in the following claims. In particular, it is to be
understood that other embodiments may be utilised and structural
and functional modifications may be made without departing from the
scope of the present invention.
[0503] In device claims enumerating several means, several of these
means can be embodied by one and the same item of hardware. The
mere fact that certain measures are recited in mutually different
dependent claims or described in different embodiments does not
indicate that a combination of these measures cannot be used to
advantage.
[0504] It should be emphasized that the term "comprises/comprising"
when used in this specification is taken to specify the presence of
stated features, integers, steps or components but does not
preclude the presence or addition of one or more other features,
integers, steps, components or groups thereof.
[0505] When a claim refers to any of the preceding claims, this is
understood to mean any one or more of the preceding claims.
[0506] The features of the method described above and in the
following may be implemented in software and carried out on a data
processing system or other processing means caused by the execution
of computer-executable instructions. The instructions may be
program code means loaded in a memory, such as a RAM, from a
storage medium or from another computer via a computer network.
Alternatively, the described features may be implemented by
hardwired circuitry instead of software or in combination with
software.
* * * * *