Note: Descriptions are shown in the official language in which they were submitted.
CA 02820539 2013-06-13
PROSTHODONTIC AND ORTHODONTIC APPARATUS AND
METHODS
BACKGROUND
1. Field of the Invention
[0001] The present invention relates to prosthodontic and orthodontic
dental procedures.
2. Related Art
[0002] Orthodontics is a dental specialty concerned with correcting
irregularities in a patient's dentition, such as malocclusion. Orthodontics
generally involves the realignment and/or repositioning of a patient's teeth.
The corrected alignment and/or position improve the function and appearance
of the teeth.
[0003] Prosthodontics is a dental specialty concerned with correcting
irregularities in a patient's dentition, such as missing, misshaped,
malformed,
or maloccluded teeth. Whereas orthodontics generally involves realignment
and/or repositioning of a patient's teeth, prosthodontics generally involves
reshaping a patient's teeth by grinding or cutting and/or building up portions
of the teeth with biocompatible dental materials. For example, a prosthodontic
procedure may involve the placement of one or more dental restorations, such
as crowns, bridges, inlays, and/or veneers. Prosthodontics also corrects for
improper tooth color and shape, which orthodontics alone cannot correct.
1
CA 02820539 2013-06-13
SUMMARY
[0004] The embodiments of the present prosthodontic and orthodontic apparatus
and methods have several features, no single one of which is solely
responsible for their
desirable attributes. Without limiting the scope of the present apparatus and
methods as
expressed by the claims that follow, their more prominent features will now be
discussed briefly. After considering this discussion, and particularly after
reading the
section entitled "Detailed Description", one will understand how the features
of the
present embodiments provide advantages, which include the ability to control
various
restorative parameters during the stages of planning and delivering
orthodontic and
prosthodontic treatment, the ability to iterate during the planning stages to
arrive at
various treatment goals and to then select a most desired treatment goal,
reduced tooth
material removed, preservation of future options for orthodontic and/or
prosthodontic
procedures, improved prosthodontic outcomes, assisting a dental professional
in
precisely identifying areas of a patient's dentition to be removed during a
prosthodontic
procedure, and assisting the dental professional in verifying whether he or
she has
removed enough tooth material to properly seat dental restorations.
[0005] One aspect of the present apparatus and methods includes the
realization
that in a prosthodontic procedure it is desirable to control restorative
parameters so that
they fall within desired ranges in the final restorative outcome. A patient
typically has
one or more goals that he or she wants to achieve through the prosthodontic
procedure.
By controlling these parameters both during the planning stages and during the
delivery
of orthodontia/prosthodontia, the patient is more likely to his or her
restorative
treatment goals.
[0006] Another aspect of the present apparatus and methods includes the
realization that in a prosthodontic procedure it is desirable to remove as
little healthy
2
CA 02820539 2013-06-13
tooth material as necessary to ensure a structurally sound final restoration.
The removal
process is irreversible and potentially uncomfortable for the patient.
Furthermore,
subsequent dental work on the same tooth typically requires further removal of
natural
tooth structure. Therefore, it is desirable to remove as little natural tooth
structure as
necessary, since the options for future modifications of the patient's
dentition become
more limited as more tooth material is eliminated. Excessive removal may also
lead to
complications, such as creating a need for endodontic treatment (root canal
treatment),
and compromised retention of the dental restoration.
[0007] Another aspect of the present apparatus and methods includes the
realization that in a prosthodontic procedure there is a prognosis for each
patient based
at least in part on the beginning configuration of that patient's dentition.
Thus, for
patients with severely maloccluded teeth, the restorative prognosis may be
poor due at
least in part to the severity of the malocclusion. By treating the patient's
dentition first
with orthodontia prior to performing the prosthodontic procedure, the
prognosis for that
patient may be significantly improved, because the new tooth positions may
require
less structural change, and enable more enhanced restorative design.
[0008] Another aspect of the present apparatus and methods includes the
realization that when placing a preparation guide over a patient's dentition
prior to tooth
modification, protruding areas of the teeth (areas that are to be removed
during the
preparation) may prevent the guide from being seated properly unless the areas
are
actually removed. Thus, it is difficult for the dental professional to
identify with
precision, areas of the teeth that are to be removed without actually cutting
the teeth. It
is also difficult for the dental professional to precisely verify whether he
or she has
removed enough tooth material to properly create the desired dental
restoration(s) to be
placed. Therefore, it would be advantageous if the dental professional had
available a
3
CA 02820539 2013-06-13
guide that could be used to measure for adequate preparation clearance while
at the
same time avoiding protruding areas of the patient's teeth that would prevent
the guide
from being seated properly even in advance of any tooth modification.
[0008a] In accordance with another aspect of the invention there is provided a
preparation guide for use during a prosthodontic procedure. The preparation
guide
includes an overlay configured to cover at least a portion of teeth in a
patient's upper or
lower arch, the overlay including a wall portion forming at least one cavity
configured
to receive the teeth. The wall portion includes at least one aperture
configured to
permit a protruding portion of the teeth to extend through the aperture to
facilitate
removal of at least a portion of the protruding portion during the
prosthodontic procedure.
[0008b] In accordance with another aspect of the invention there is provided a
method of fabricating a preparation guide for use during a prosthodontic
procedure.
The method involves receiving a first virtual digital model of a patient's
dentition in
a beginning configuration, and manipulating the virtual digital model using
computer
software to create a second virtual digital model of the patient's dentition
in a desired
final configuration. The method further involves causing the computer to
superimpose
the first and second virtual digital models, identifying, in the superimposed
models,
intersection boundaries at areas where the dentition of the first model
protrudes beyond
the dentition of the second model, and fabricating the preparation guide to
substantially
conform to the second model and having apertures defined by the intersection
boundaries.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The disclosed embodiments of the present prosthodontic and orthodontic
apparatus and methods will now be discussed in detail with an emphasis on
4
CA 02820539 2013-06-13
highlighting the advantageous features. These embodiments depict the novel and
non-
obvious apparatus and methods shown in the accompanying drawings, which are
for
illustrative purposes only. These drawings include the following figures, in
which like numerals indicate like parts:
[0010] FIG. l is a table rating various orthodontic/prosthodontic treatment
options
against restorative parameters;
[0011] FIG. 2 is a schematic illustration of two teeth in a pretreatment
configuration;
[0012] FIG. 3 is a schematic illustration of the teeth of FIG. 2 in a post-
treatment
configuration according to one example prosthodontic treatment plan;
[0013] FIG. 4 is a schematic illustration of the teeth of FIG. 2 in a post-
treatment
configuration according to another example prosthodontic treatment plan;
[0014] FIG. 5 is a schematic illustration of the teeth of FIG. 2 in a post-
treatment
configuration according to one example orthodontic/prosthodontic treatment
plan;
[0015] FIG. 6 is a schematic illustration of the teeth of FIG. 2 in a post-
treatment
configuration according to another example orthodontic/prosthodontic treatment
plan;
[0016] FIG. 7 is a schematic illustration of the teeth of FIG. 2 in a post-
treatment
configuration according to another example orthodontic/prosthodontic treatment
plan;
[0017] FIG. 8 is a schematic illustration of the teeth of FIG. 2 in a post-
treatment
configuration according to one example orthodontic treatment plan;
[0018] FIG. 9 is a flowchart illustrating steps that may be performed in
certain
embodiments of the present methods;
5
CA 02820539 2013-06-13
[0019] FIG. 10 is a perspective view of one embodiment of an
aligner
that may be used in connection with certain embodiments of the present
apparatus and methods;
[0020] FIG. 11 is a flowchart illustrating steps that may be
performed
in certain embodiments of the present methods;
[0021] FIG. 12 is a front elevation view of a tooth in a beginning
configuration;
[0022] FIG. 13 is a front elevation view of the tooth of FIG. 12
superimposed with a desired final configuration for the tooth, according to
one
embodiment of the present methods;
[0023] FIG. 14 is a front elevation view of the tooth of FIG. 12
superimposed with a desired final configuration for the tooth, according to
one
= embodiment of the present methods;
[0024] FIG. 15 is a front elevation view of the tooth of FIG. 12
and
one embodiment of the present prosthodontic apparatus;
[0025] FIG. 16 is a front elevation view of the tooth of FIG. 12
and
one embodiment of the present prosthodontic apparatus, illustrating the step
of
removing a portion of the tooth that extends beyond the apparatus;
[0026] FIG. 17 is a front elevation view of the tooth of FIG. 12
after it
has been prepared according to one embodiment of the present methods;
[0027] FIG. 18 is a front elevation view of the tooth of FIG. 12
and a
dental restoration placed in accordance with one embodiment of the present
methods;
6
CA 02820539 2013-06-13
[0028] FIG. 19 is a flowchart illustrating steps in another embodiment
of the present methods;
[0029] FIG. 20 is a graph representing the start and stop points which
yield the least amount of tooth mass removal and/or mass build-up over a
given amount of available treatment time;
[0030] FIG. 21 is a flowchart illustrating a process for simulating the
creation of veneer models using orthodontic and prosthodontic techniques in
accordance with one embodiment of the present invention;
[0031] FIGS. 22A and 22B are simplified views of a dental arch in a
pre-treatment configuration and in a final configuration in accordance with
one embodiment of the present invention, respectively;
[0032] FIG. 23 is a flowchart illustrating steps in an embodiment of
the process of FIG. 21;
[0033] FIG. 24 shows a simplified side view of a tooth in an Initial
configuration and a Prepared configuration in accordance with one
embodiment of the present invention;
[0034] FIG. 25 shows a simplified side view and a top view of the
sweep volume of a Prepared tooth configuration in accordance with one
embodiment of the present invention; and
[0035] FIG. 26 is a flowchart illustrating a process for preparing an
actual restoration in accordance with the present invention.
7
CA 02820539 2013-06-13
DETAILED DESCRIPTION
[0036] It should be understood that the techniques of the present
invention may be implemented using a variety of technologies. For example,
methods described herein may be implemented in software executing on a
computer system, or implemented in hardware using either a combination of
microprocessors or other specially designed application specific integrated
circuits, programmable logic devices, or various combinations thereof. In
particular, methods described herein may be implemented by a series of
computer-executable instructions residing on or carried by a suitable
computer-readable medium. Suitable computer-readable media may include
volatile memory (e.g., RAM) and/or non-volatile memory (e.g., ROM, disk).
[0037] Certain embodiments of the present prosthodontic and
orthodontic apparatus and methods advantageously combine the benefits of
orthodontic treatment with a prosthodontic procedure to enhance the final
outcome of the procedure. The embodiments produce a healthy-looking smile
with a reduced amount of tooth structure removed as compared to a traditional
prosthodontic procedure with no orthodontia. The reduction in tooth structure
removed reduces complications that can arise from over-reduction of teeth,
such as sensitivity. It also helps to ensure that the reduction may be
performed
in an accurate, reproducible manner. Further, the options for future
modifications of the patient's dentition are increased, since a greater
proportion of the patient's original dentition remains after the procedure has
been completed.
8
CA 02820539 2013-06-13
[0038] Certain other embodiments of the present apparatus and
methods advantageously enable one or more restorative parameters to be
controlled during a prosthodontic procedure. Upon identifying one or more
parameters of interest, a dental professional can iterate processes of virtual
orthodontia and virtual prosthodontia to observe whether each iteration
produces a desired outcome for the parameter(s) of interest. The dental
professional may perform the iterations together with the patient. The
parameters of interest may include, for example, time of treatment, volume of
tooth structure removed, final aesthetics and/or alignment of lingual tooth
surfaces or other parameters.
[0039] Certain other embodiments of the present apparatus and
methods advantageously assist a dental professional in identifying areas of a
patient's dentition to be removed during a prosthodontic procedure. The
present embodiments also assist the dental professional in verifying whether
he or she has removed enough tooth material to properly create dental
restoration(s) that are to be placed. The prosthodontic methods described
herein may be performed on a patient's entire dentition or on just one tooth.
For simplicity, however, some of the present apparatus and methods are
shown in the figures with reference to only a single tooth.
[0040] Certain other embodiments of the present apparatus and
methods advantageously assist a dental professional in forming an orthodontic
treatment plan oriented on optimal veneer usage. These embodiments assist
the dental professional in quantifying parameters used to properly create
dental restoration(s) that are to be placed.
9
CA 02820539 2013-06-13
Treatments
[0041] Embodiments of the present methods may begin when a patient
first consults a dental professional (which may include, but is not limited
to, a
dentist, an orthodontist, a lab technician, a dental product provider, a
dental
service provider and the like) regarding an orthodontic procedure and/or a
prosthodontic procedure. During the initial consultation, the dental
professional and the patient may discuss the patient's treatment goal(s) and
any constraints that might limit the range of available treatment options. For
example, the patient may desire to have his or her smile enhanced prior to his
or her wedding, but the patient may not consult the dental professional until
six months prior to the wedding. In such a situation, the timeframe for
treatment is limited, and an appropriate orthodontic/prosthodontic treatment
plan must be set to fit within the timeframe.
[0042] In the table of FIG. 1, the left-hand column lists seven
orthodontic/prosthodontic treatment options represented by the letters A-G.
Options A-G are schematically illustrated in FIGS. 2-8, which are discussed in
detail below. The top row of the table lists four restorative parameters that
may be of interest to the patient. The exemplary four restorative parameters
are: time required to complete the orthodontic/prosthodontic treatment,
reduction in volume of tooth structure resulting from prosthodontic treatment,
final aesthetics upon completion of treatment (including teeth color,
realistic
thickness of teeth and the like), and alignment of lingual tooth surfaces (on
tongue side of teeth) upon completion of treatment. As explained in detail
CA 02820539 2013-06-13
below, the table assesses each of the treatment options by assigning
qualitative
values to each of the restorative parameters for that treatment option. Those
of
ordinary skill in the art will appreciate that there may be additional
restorative
parameters not listed in FIG. 1 that may be of interest to some patients.
Accordingly, the listed parameters should not be interpreted as limiting the
scope of the present embodiments.
[0043] In FIG. 1, each of the orthodontic/prosthodontic treatment
options is rated against the four listed parameters. To assess a given
treatment
option, the dental professional and/or patient locates that option in the
leftmost
column and reads across the table. The symbols appearing in each column
indicate whether the treatment option produces a positive outcome or a
negative outcome for the parameter of that column. If a treatment option
produces a positive outcome for a given parameter, one or more + signs appear
in the column for that parameter. If a treatment option produces a negative
outcome for a given parameter, one or more ¨ signs appear in the column for
that parameter. Multiple + or ¨ signs indicate that that parameter is
particularly positive or particularly negative for that treatment option. If a
0
appears in a column, then that parameter is considered neutral with respect to
that treatment option.
[0044] FIG. 2 schematically illustrates a first tooth X and a second
tooth Y in a pretreatment configuration, while FIGS. 3-8 illustrate the same
teeth in various post-treatment configurations. In FIGS. 2-8, the illustrated
teeth are molars, and the cuspal (chewing) surface of each molar faces the
11
CA 02820539 2013-06-13
viewer. The lingual (tongue side) surface of each tooth faces downward, and
the buccal (opposite the tongue side) surface of each tooth faces upward.
[0045] In the pretreatment configuration of FIG. 2, tooth X is
positioned closer to the tongue than tooth Y. Thus, neither the lingual
surfaces
nor the buccal surfaces of the teeth are aligned. Further, a portion of tooth
Y
is overlapping a portion of tooth X. Thus, to align the lingual and buccal
surfaces of the teeth, either the teeth must first be moved away from each
other, or the overlapping portions of one or both teeth must be removed.
[0046] FIG. 1 includes option A, which represents no orthodontic or
prosthodontic treatment and provides a baseline from which to relatively
measure other outcomes. Thus, the teeth remain as they appear in FIG. 2.
Referring to the table in FIG. 1 and reading across the first row, option A
produces a very strongly positive outcome (+++) for the time required to
complete the treatment, because there is no treatment. Option A also produces
a very strongly positive outcome (+++) for reduction in volume of tooth
structure, because no tooth structure is removed. Finally, treatment option A
produces strongly negative outcomes (¨ ¨ ¨) for both final aesthetics and
alignment of lingual tooth surfaces, because no improvements are made in
these areas.
[0047] FIG. 3 schematically illustrates one treatment plan that involves
only prosthodontics. To transform the teeth from the configuration of FIG. 2
into the configuration of FIG. 3, the overlapping portion of tooth Y is cut or
ground away, and a veneer is applied to the buccal surface of tooth X. In
12
CA 02820539 2013-06-13
order to firmly secure the veneer to the tooth, small portions on either side
of
tooth X are removed to form butt joints with the veneer.
[0048] Referring to the table in FIG. 1 and reading across the second
row, treatment option B produces a strongly positive outcome (++) for the
time required to complete the treatment, because the treatment involves only
prosthodontia, which may be completed in a much shorter timeframe than
orthodontia. However, treatment option B produces a negative outcome (¨)
for reduction in volume of tooth structure, since the overlapping portion of
tooth Y is removed and small portions on either side of the tooth X are
removed to form the butt joints. Treatment option B produces a more negative
outcome (¨ ¨) for final aesthetics, since a very thick veneer is added to
tooth
X, and since there is no matching veneer added to tooth Y. Thus, the color of
tooth Y is not improved, and there may be some color contrast between the
buccal surfaces of teeth X and Y. Finally, treatment option B produces a very
strong negative outcome (¨ ¨ ¨) for alignment of lingual tooth surfaces, the
misalignment of the lingual surfaces is not corrected at all.
[0049] FIG. 4 schematically illustrates another treatment plan that also
involves only prosthodontics. To transform the teeth from the configuration of
FIG. 2 into the configuration of FIG. 4, the overlapping portion of tooth Y is
ground away, and a veneer is applied to the buccal surface of tooth X. In this
embodiment, a veneer is also applied to the buccal surface of tooth Y. As in
treatment option B above, small portions on either side of tooth X are removed
to form butt joints with the veneer. To secure the veneer to tooth Y, a thin
13
CA 02820539 2013-06-13
wall of the buccal surface of tooth Y is removed in addition to small portions
on either side of tooth Y for butt joints.
[0050] Referring to the table in FIG. 1 and reading across the third
row, treatment option C produces a strong positive outcome (+ +) for the time
required to complete the treatment, because the treatment involves only
prosthodontia. Treatment option C produces a strong negative outcome (¨ ¨)
for reduction in volume of tooth structure, because not only is the
overlapping
tooth structure of tooth Y removed, but tooth structure is removed from tooth
X and tooth Y to form butt joints and to make room for the veneer on tooth Y.
Treatment option C produces a neutral outcome (0) for final aesthetics,
because although there is a very thick veneer added tooth X, the color of both
teeth are improved because of the matching veneers. Finally, like treatment
option B treatment option C also produces a very strong negative outcome (¨ ¨
¨) for alignment of lingual tooth surfaces.
[0051] In order to arrive at the best possible outcome for a patient's
specific condition or treatment requirements, trade-offs may be made between
each of the restorative parameters. It is apparent that for some situations
where, for example, aesthetics and lingual alignment are important parameters,
and particularly where it is desired to minimize the amount of tooth
reduction,
some combination of orthodontics and prosthodontics may be indicated.
[0052] FIG. 5 schematically illustrates another treatment plan that
involves both orthodontics and prosthodontics. To transform the teeth from
the configuration of FIG. 2 into the configuration of FIG. 5, the overlapping
portion of tooth Y is ground away, and tooth X is moved forward (away from
14
CA 02820539 2013-06-13
the tongue). However, tooth X is only moved forward through the distance d,
such that while alignment of the buccal and lingual surfaces of the teeth is
improved, it is not made perfect. In treatment option D veneers are also
applied to the buccal surfaces of teeth X and Y.
[0053] Referring to the table in FIG. 1 and reading across the fourth
row, treatment option D produces a positive outcome (+) for the time required
to complete the treatment, because although the treatment involves
orthodontia, the treatment nevertheless takes less time than a treatment
option
that involves more movement of tooth X. Treatment option D produces strong
negative outcome (¨ ¨) for reduction in volume of tooth structure, because not
only is the overlapping tooth structure of tooth Y removed, but tooth
structure
is removed from tooth X and tooth Y to form butt joints and to make room for
the veneer on tooth Y. Treatment option D produces a positive outcome (+)
for final aesthetics, since, due to the movement of tooth X, relatively thin
veneers are added to both teeth. Finally, treatment option D produces a
positive outcome (+) for alignment of lingual tooth surfaces, because the
alignment is improved over that of the pretreatment configuration.
[0054] FIG. 6 schematically illustrates another treatment plan that also
involves both orthodontics and prosthodontics. To transform the teeth from
the configuration of FIG. 2 into the configuration of FIG. 6, the overlapping
portion of tooth Y is ground away, and tooth X is moved forward (away from
the tongue). In contrast to treatment option D, tooth X is moved forward
through the distance D until the lingual surfaces of the teeth align. In
CA 02820539 2013-06-13
treatment option E, veneers are also applied to the buccal surfaces of teeth X
and Y.
[0055] Referring to the table in FIG. 1 and reading across the fifth row,
treatment option E produces a negative outcome (¨) for the time required to
complete the treatment, because the treatment involves orthodontia to move
tooth X through a greater distance D when compared to other treatment
options. Treatment option E produces a strong negative outcome (¨ ¨) for
reduction in volume of tooth structure, because not only is the overlapping
tooth structure of tooth Y removed, but tooth structure is removed from tooth
X and tooth Y to form butt joints and to make room for veneers on both tooth
X and tooth Y. Treatment option E produces a strong positive outcome (+ +)
for final aesthetics, because thin veneers are added to both teeth and both
teeth
appear to be of normal thickness. Finally, treatment option E produces a
strongly positive outcome (+ +) for alignment of lingual tooth surfaces,
because the alignment is greatly improved over that of the pretreatment
configuration.
[0056] FIG. 7 schematically illustrates another treatment plan that
involves orthodontics and prosthodontics. To transform the teeth from the
configuration of FIG. 2 into the configuration of FIG. 7, the teeth are moved
away from one another (as represented by the oppositely directed arrows on
either side of the teeth) and tooth X is moved forward (away from the tongue)
through the distance D until the buccal and lingual surfaces of the teeth
align.
However after the teeth are moved, treatment option F includes adding veneers
to the buccal surfaces of tooth X and tooth Y.
16
CA 02820539 2013-06-13
[0057] Referring to the table in FIG. 1 and reading across the sixth
row, treatment option F produces a strong negative outcome (¨ ¨) for the time
required to complete the treatment, because the treatment involves orthodontia
to move tooth X through a distance D and to move tooth X away from tooth
Y. Treatment option F produces a very neutral outcome (0) for reduction in
volume of tooth structure, because only a small amount of tooth structure is
removed on from tooth X and tooth Y to form butt joins for the veneers.
Treatment option F produces a very strong positive outcome (+ + +) for final
aesthetics because the teeth are properly aligned, the teeth appear to be of
normal thickness and the veneers correct any discoloration or misshapenness
from the pretreatment configuration. Finally, treatment option F produces a
strong positive outcome (+ +) for alignment of lingual tooth surfaces, because
the alignment is greatly improved over that of the pretreatment configuration.
[0058] FIG. 8 schematically illustrates another treatment plan that
involves only orthodontics. To transform the teeth from the configuration of
FIG. 2 into the configuration of FIG. 8, the teeth are moved away from one
another (as represented by the oppositely directed arrows on either side of
the
teeth) and tooth X is moved forward (away from the tongue) through the
distance D until the buccal and lingual surfaces of the teeth align.
[0059] Referring to the table in FIG. 1 and reading across the seventh
row, treatment option G produces a strong negative outcome (¨ ¨) for the time
required to complete the treatment, because the treatment involves orthodontia
to move tooth X through a distance D and to move tooth X away from tooth
Y. Treatment option G produces a very strong positive outcome (+ + +) for
17
CA 02820539 2013-06-13
reduction in volume of tooth structure, because no tooth structure is removed.
Treatment option G produces a positive outcome (+) for final aesthetics
because the teeth are properly aligned and appear to be of normal thickness.
However, because no veneers are added to the teeth, any discoloration or
misshapenness from the pretreatment configuration remains. Finally,
treatment option G produces a strong positive outcome (+ +) for alignment of
lingual tooth surfaces, because the alignment is greatly improved over that of
the pretreatment configuration.
[0060] While the examples described with respect to FIGS. 2-8 relate
to two teeth, similar principals apply to other configurations of maloccluded
and misshapen teeth and apply to patient with two or more maloccluded teeth.
[0061] After the initial consultation between the patient and the dental
professional, the dental professional and the patient may develop an
orthodontic treatment plan and/or a prosthodontic treatment plan. The
orthodontic treatment plan may transform the patient's dentition from its
beginning configuration to an intermediate configuration, and the
prosthodontic treatment plan may transform the patient's dentition from the
intermediate configuration to a final configuration. The intermediate
configuration may also be referred to as an orthodontic treatment goal, and
the
final configuration may also be referred to as a restorative treatment goal.
[0062] With reference to FIG. 9, a computer-generated, three-
dimensional, virtual model of the patient's dentition in the beginning
configuration is created, as shown at step S10. Unlike some 3-D educational
software which show representative "typodont" models for illustrative
18
CA 02820539 2013-06-13
purposes, this model represents the patient's actual dentition in a beginning
configuration.
The virtual model may be generated prior to any tooth preparation, so that the
model
represents the patient's dentition in a pretreatment state. Some processes for
making such
a virtual model are described in, for example, U.S. Patent Application
Publication No. US
2006/0154207, published on July 13, 2006 and in U.S. Patent Application
Publication
No. 2008/0206705, published on August 28, 2008 by Kaza et al.
[0063] With continued reference to FIG. 9, the virtual model of the beginning
configuration using virtual orthodontia may be transformed to create a
computer-
generated, three-dimensional, virtual model of the patient's dentition in an
intermediate
configuration, as shown at step S12. The virtual orthodontia may include
manipulation
and movement of teeth in the virtual model. The virtual model of the
intermediate
configuration may be transformed using virtual prosthodontia to create a
computer-
generated, three-dimensional, virtual model of the patient's dentition in a
desired final
configuration, as shown at step S14. The virtual prosthodontics may include
one or more
modifications of the virtual model, such as tooth mass removal or build-up
and/or the
placement of one or more dental restorations. Those of ordinary skill in the
art will
appreciate that steps S12 and S14 may be performed in any order, and may even
be
performed simultaneously. In addition, steps S12 and S14 may be iterated upon.
During
each iterative step, the final model may be evaluated and iterated again or
finalized into a
19
CA 02820539 2013-06-13
treatment plan. These iterative steps are described in greater detail below
with respect
to FIG. 11.
[0064] Finalizing a treatment plan may include setting the intermediate and
final
configurations, as shown at step S16 in FIG. 9. Once these configurations are
set, the
orthodontic treatment plan and the prosthodontic treatment plan are generated,
as
shown at step S18. The orthodontic treatment plan may transform the dentition
from
the beginning configuration to the intermediate configuration, and the
prosthodontic
treatment plan will transform the dentition from the intermediate
configuration to the
final configuration or restorative treatment goal.
[0065] Once the treatment plan is finalized, the next step in the present
method may
be to deliver a course of orthodontic treatment according to the orthodontic
treatment
plan, as shown at step S20 in FIG. 9. The orthodontia may proceed using any
well-
known apparatus and methods, such as orthodontic brackets and wires (braces).
Alternatively, or in addition, the orthodontia may include a series of plastic
orthodontic
appliances or aligners. FIG. 10 illustrates one such aligner 50 that is
adapted to fit over
a patient's lower arch 52. The aligners may be a polymeric shell having a
teeth-
receiving cavity. The patient wears the series of aligners in order to achieve
incremental repositioning of individual teeth in his or her jaw.
[0066] The polymeric aligner 50 of FIG. 10 may be formed from a thin sheet of
a suitable elastomeric polymer, such as Tru-Tain 0.030" thermal
CA 02820539 2013-06-13
forming dental material, available from Tru-Tain Plastics of Rochester, MN.
Other aligner materials can include, but are not limited to polyester,
polyurethane, polypropylene, polycarbonate, poly-blend, and poly-laminates.
Usually, no wires or other structures are provided for holding the aligner in
place over the teeth, though it may be possible to incorporate auxiliary
devices
such as wires, hooks, and elastics into the aligners to assist in appliance
retention. It is also possible to provide individual anchor attachments
directly
on the teeth, with corresponding receptacles or apertures in the aligner so
that
the aligner can apply either a retentive or a supplemental force on the tooth
that would not be possible in the absence of such an anchor.
[0067] The aligners are generated using data representing the patient's
teeth. The data may be from scans of dental impressions, dental casts, and/or
direct scans of the patient. Each polymeric shell may be configured so that
its
tooth-receiving cavity has a geometry corresponding to an incremental tooth
arrangement intended for the patient. The patient's teeth are repositioned
from
their initial arrangement to the next incremental arrangement by placing the
aligners sequentially over the teeth. The patient wears each aligner until the
teeth have conformed to the position defined by the aligner. At that point,
the
patient moves onto the next aligner stage of the planned course of treatment
and replaces the old aligner with the next aligner in the series until the
intended treatment outcome is achieved. The course of treatment may require
a recalibration scan and additional aligners if the teeth do not exactly track
according to the design within the aligner. However, because the aligners are
removable and not bonded to the teeth, the process is convenient and hygienic
21
CA 02820539 2013-06-13
for the patient, generally more so than traditional braces, which are affixed
directly to the teeth and not intended to be removed by the patient during the
course of treatment.
[0068] The polymeric shell can fit over any and typically all teeth
present in the upper or lower jaw. Often, only a select few of the teeth are
repositioned at a given time while remaining teeth provide a base or an anchor
region for holding the aligner in place as the aligner applies a repositioning
force against the tooth or teeth to be repositioned. In many cases, all teeth
may be repositioned at some point during the treatment. In such cases, the
moved teeth may also serve as a base or anchor region for holding the aligner.
[0069] Upon completion of the orthodontic treatment plan, a dental
professional may perform one or more prosthodontic procedures according to
the prosthodontic treatment plan. As part of the prosthodontic procedure(s),
the dental professional prepares the necessary teeth by reducing the tooth
surfaces as needed to ensure proper retention, strength, and aesthetics for
the
final restoration. The prepared teeth may require one or more provisional
restorations. In some situations, however, the final restoration(s) may be
immediately fabricated in the dental professional's office and placed without
the need for any provisionals. An example of an immediate fabrication system
is the Siriona CERECTM milling machine, which uses an in-office scan of the
prepared dentition, the creation of a virtual restoration over the preparation
scan, and the milling of a porcelain block according to the virtual
restoration
in consideration of the preparation scan.
22
CA 02820539 2013-06-13
[0070] Prior to placing the dental restoration(s) on the patient's
dentition, at least one of tooth surface removal, cutting and/or reshaping may
be performed, as shown in step S22 in FIG. 9. The removal/cutting/reshaping
prepares the dentition to receive the dental restoration(s). As discussed
above,
such preparation generally involves the removal of at least a portion of a
tooth,
its enamel and/or dentin, and some or all pre-existing restorations on the
tooth.
The reshaping may also involve building up some areas of the dentition using
biocompatible materials such as composite, fiberglass, carbon fiber, gold,
amalgam, titanium, and/or stainless steel. When removing tooth material to
accommodate a dental restoration, generally 1 mm of tooth material is
removed to ensure adequate restoration strength and desired aesthetics.
However, as those of ordinary skill in the art will appreciate more or less
tooth
material may be removed.
[0071] During the steps of removal/cutting/reshaping, the accuracy and
design of the removal, cutting and/or reshaping may be periodically verified.
In one embodiment, one or more preparation guides may be positioned over
the patient's dentition. The preparation guide, which resembles an aligner and
is typically manufactured in a similar way, may embody the final restorative
configuration. Clearances between teeth surfaces and the preparation guide
may be measured to verify that the desired amounts of tooth surface have been
removed. To determine whether adequate tooth material has been removed,
the guide may be seated on the teeth and any interference between the tooth
and the guide may be removed. Once the guide is fully seated, the clearances
between the guide and the teeth are checked and additional tooth material is
23
CA 02820539 2013-06-13
removed until adequate clearances are achieved between the inner surfaces of
the guide and the surfaces of the teeth receiving the final restoration(s).
[0072] After the desired amount of tooth material has been removed in
conjunction with the preparation guide, a provisional or final restoration may
be prepared and affixed on the patient's dentition, as shown in step S24 in
FIG. 9. An adhesive, such as dental cement, may be used to affix the
restoration on the teeth to prevent it from leaking and/or dislodging.
[0073] As described above, in the foregoing methods at least some of
the steps may be performed in an iterative fashion, and may include one or
more sub-steps. The iteration enables a dental professional and a patient to
focus on one or more restorative parameters that are of interest to the
patient,
and to control the outcome of the treatment with respect to these parameters.
Therefore, prior to or during the present methods the dental professional and
the patient may identify one or more restorative parameters that are of
interest
to the patient. As discussed above with respect to FIG. 1, these parameters
may include: treatment time, volume of tooth structure removed, final
aesthetics and/or alignment of lingual tooth surfaces. Moreover, after
creating
a virtual model of the patient's dentition in the beginning configuration
(step
S10, FIG. 11), the dental professional may transform the virtual model to
create virtual models representing the desired intermediate configuration
(S12)
and final configuration (S14). In addition, at step S26 the dental
professional
may evaluate the one or more restorative parameters of interest, and then
iterate the movement steps and again evaluate the restorative parameter(s).
= The dental professional and the patient may repeat these iterative steps
until
24
CA 02820539 2013-06-13
the restorative parameter(s) fall within desired ranges. Again, those of
ordinary skill in the art will appreciate that the iterative steps outlined
above
may be performed in any order.
[0074] In step S26, the evaluation step may focus on the total volume
of tooth structure removed in order to reach the final configuration. The
evaluation may be based on, for example, a desired threshold of the total
volume of tooth structure. For example, the dental professional may begin by
superimposing the dentition in the intermediate configuration and the
dentition
in the final configuration to identify on the superimposed models the
intersection boundaries at the areas where the dentition of the intermediate
configuration protrudes beyond the dentition of the final configuration. Using
the three-dimensional geometrical models, the volume of the protruding tooth
structure may be calculated. The volume of the protruding dentition
represents the volume of tooth structure that may be removed by the dental
professional during the prosthodontic procedure.
[0075] As a result of the evaluation and visualization, the dental
professional, perhaps after consulting the patient, may modify the orthodontic
treatment plan by moving and aligning the teeth using virtual orthodontics
into
a configuration that varies from the orthodontic treatment goal. The dental
professional may also modify the prosthodontic treatment plan by modifying
the teeth using virtual prosthodontics into a configuration that varies from
the
restorative treatment goal. The dental professional may repeat these steps
several times. In addition, or in the alternative, as a result of the
evaluation
and visualization, the dental professional may modify the orthodontic
CA 02820539 2013-06-13
treatment goal and/or the restorative treatment goal. For example, the dental
professional may modify the restorative treatment goal by modifying the
desired final tooth position goal and/or tooth shape goal.
[0076] In step S26 the dental professional may superimpose the
modified models to determine the impact of the modifications on the volume
of tooth structure that extends outward from the intersection boundaries. The
dental professional may continue to modify the virtual representations of the
tooth structures in both the virtual orthodontic plan and virtual restorative
goal
models until the dental professional has iteratively arrived at an acceptable
preparation design that provides for a desired threshold value of the
parameters of interest. In the present invention, the threshold value
represents
either a maximum, or if appropriate, a minimum condition that the dental
professional determines is an acceptable variation to any given restorative
parameter. For example, the dental professional may set a threshold value that
represents the maximum amount of the total volume of the tooth structure to
be removed to create the final tooth configuration. A threshold value may also
be, for example, the maximum amount of time available for treatment or the
maximum thickness of a veneer to be placed on a tooth.
[0077] The ability to virtually iterate the preparation specifications as
applied to the virtual beginning model of the dentition as provided in steps
S12 and S14 provides the dental professional the ability to modify the
preparation design prior to any actual moving or cutting of the teeth. In
addition, the dental professional may also visualize the impact of the
preparation to the actual tooth, for example, in terms of volume of tooth
26
CA 02820539 2013-06-13
material removed, the different areas of tooth affected, and the depth of the
preparation, which is advantageous for avoiding sensitivity or other
treatments, such as root canals.
[0078] Once the dental professional has arrived at a preparation design
that meets desired thresholds for the restorative parameters of interest, then
the
dental professional may set the intermediate and final configurations, as
shown at step S28. The dental professional may then map out the orthodontic
and prosthodontic treatment plans based upon the beginning, intermediate and
final configurations, as shown at step S30.
[0079] Using the orthodontic and prosthodontic treatment plans, the
dental professional may next create, or have created, orthodontic appliances
and restorative preparations, as shown at step S32. Steps S20, S22 and S24
may then proceed as shown in FIG. 11 and as described above with respect to
FIG. 9.
[0080] Many of the various embodiments included in the method steps
described with reference to FIGS. 9 and 11 are illustrated in the following
example.
[0081] In accordance with one embodiment of the present methods, a
dental professional may begin a restorative procedure, by first meeting with a
patient to determine which of the restorative factors available are achievable
to
the degree desired by the patient given the patient's treatment priorities.
For
example, the patient may present to the dentist having a malocclusion like
that
shown in FIG. 2. In this example, the patient may explain to the dentist that
she is anticipating a wedding day that is only six months in the future. The
27
CA 02820539 2013-06-13
bride-to-be wants her teeth (tooth X and Y, in this example) to appear as
white
and as straight as possible, but she is not concerned with the lingual surface
of
her teeth as it does not bother her in its present condition. The dental
professional notes that the patient has relatively unhealthy teeth and thus
determines that the degree of tooth volume reduction, if needed, should be
minimized.
[0082] = The dental professional may apprise the patient with her
options, while referring to the table in FIG. 1. Of the options available, the
dental professional mentions that Options B and C provide the best desired
outcome regarding time of treatment in keeping with the patient's six-month
timeframe. However, the dental professional may explain that Option B is not
as aesthetically desirable as Option C, since Option B does not provide for a
matching veneer between the subject teeth. The dental professional may also
explain that Options B and C require a relatively thick veneer be placed on
one
of the subject teeth to create the illusion that the buccal surface of the
teeth are
properly aligned.
[0083] The patient reviews Options B and C and determines that
Options C provides a semi-satisfactory solution, but that the thick veneer is
problematic for her. The dental professional may then suggest that the
thickness of the veneer may be reduced by moving the subject teeth first, as
in
Option D. The patient asks to visualize the anticipated results.
[0084] To begin, the dental professional scans or photographs the
patient's actual dentition to create the virtual model and inputs the data
into a
computer running the modeling software.
28
CA 02820539 2013-06-13
[0085] The dental professional may then manipulate the virtual
beginning model using the computer software, to simulate the effect of
orthodontic treatment by virtually repositioning the subject teeth, tooth X
and
tooth Y, into a different position. In this example, the dental professional
determines that to expedite tooth movement, the portion of tooth Y that
overlaps tooth X is to be removed.
[0086] Using the software model, the dental professional may quantify
a distance d1 (FIG. 5) that may be achieved in the prescribed timeframe (e.g.
6
months), which requires a certain amount of tooth volume reduction VI, and
yields a veneer thickness T1. The dental professional may then manipulate the
tooth X and tooth Y again to generate a distance d2 that may be achieved in
the
prescribed timeframe, which requires an amount of tooth volume reduction V,
and yield a veneer thickness T2 and so on until the dental professional
decides
that he has generated a number of suitable options (d 1 . n, V1...n, TI...n)
for the
patient to review. Since the dental professional is concerned with the amount
of tooth volume reduction, the dental professional may set a threshold value
for the amount of tooth volume reduction (V1, V2.. .V) that he has determined
is tolerable for this patient.
[0087] Next, the dental professional, in consultation with the patient,
may review the options and visualize the results, to determine, which provides
a reduction to the thickness of the veneer to the patient's satisfaction. If
the
patient is satisfied, and the dental professional and the patient have agreed
upon the desired final configuration for the dentition, the dental
professional
29
CA 02820539 2013-06-13
may then use the computer software to create a suitable prescription for
moving the patient's teeth.
[0088] In the above example, before finalizing the prescription, the
patient informs the dental professional that her wedding plans have been
canceled, but that she still desires to have her teeth restored within the
next 12
months. The dental professional explains that, since there is more time
available for an orthodontic procedure, the patient has more options to choose
from with regard to the restoration, for example, Options E, F, and G of FIG.
1.
[0089] The dental professional then revisits the virtual model of the
patient's dentition and again begins to manipulate the teeth to determine, as
before, which Options now provide the patient with the most suitable outcome
given the new timeframe.
Preparation Guides
[0090] Although not shown in FIG. 11, the treatment plans could also
be used to create preparation guides or templates to help in the restorative
aspect of tooth preparation, temporary restoration creation and creation of
virtual wax-ups and possible final veneers. An example of a preparation guide
that could be created using the treatment plans is discussed below with
reference to FIGS. 12-19.
[0091] FIG. 12 illustrates a tooth 20 in a beginning configuration, prior
to any prosthodontic modifications. In accordance with one embodiment of
CA 02820539 2013-06-13
the present methods, a dental professional may begin a prosthodontic
procedure by creating a first virtual model of a patient's dentition in a
beginning configuration, as shown at step S100 in FIG. 19. The virtual model
may be generated by digitally scanning and/or photographing the actual
dentition and inputting the data into a computer running modeling software.
The dental professional may store the beginning model for use in a
comparison, as described below.
[00921 The dental professional may then manipulate the virtual
beginning model using the computer software, as shown at step S102. This
manipulation may include simulating the effect of orthodontic treatment by
virtually repositioning one or more teeth into a different position, such that
the
amount of tooth reduction necessary becomes reduced or more balanced for
the desired restorative outcome. On the computer screen, the dental
professional may also remove portions of the teeth and/or build-up other
portions of the teeth in order to generate a second virtual model of the
patient's dentition in a desired final configuration (S102). After
consultation
with the patient (S104), the dental professional may perform additional
modifications to the second virtual model (S106) until the dental professional
and the patient agree on the desired final configuration.
[0093] FIG. 13 illustrates one example of tooth modifications with
which the dental professional may experiment, and about which the dental
professional and the patient may confer. In FIG. 13, the tooth 20 is shown in
the beginning configuration (solid lines) and in one possible final
configuration (dashed lines). To reach the final configuration the dental
31
CA 02820539 2013-06-13
professional applies a dental restoration to the tooth 20. In the illustrated
embodiment, the dental restoration is a veneer 22. However, those of ordinary
skill in the art will appreciate that the present methods may involve the
placement of any type of dental restoration, such as a bridge or a crown.
Before placing the veneer 22 on the tooth 20, the dental professional prepares
the tooth 20 by removing some surface material. For example, the dental
professional may need to completely cut off a portion 24 (upper shaded
portion) of the tooth 20 that would extend past the veneer 22. In other areas
26 (lower shaded portions) the dental professional may need to remove just a
portion of the tooth surface (generally about 1 mm) in order to create room
for
the veneer.
[0094] Once the dental professional and the patient have agreed upon
the desired final configuration for the dentition, the dental professional may
then use the computer software to superimpose the first (beginning) and
second (final) virtual models, as shown at step S108 in FIG. 19. For example,
FIG. 14 illustrates a model of a final configuration including the veneer 22
superimposed over a model of the actual configuration of the tooth 20. In the
superimposed models, the portion 24 of the beginning dentition protrudes
beyond the veneer 22. The dental professional will remove the protruding
portion 24 from the patient's actual dentition during the prosthodontic
procedure.
[0095] To enhance the precision with which he or she removes
protruding portions of the patient's dentition, the dental professional may
use
the superimposed models to generate a preparation guide that emphasizes the
32
CA 02820539 2013-06-13
protruding portions. The preparation guide may be an overlay that
substantially conforms to the second dentition model, but includes apertures
that enable protruding portions of the actual dentition to extend beyond the
overlay so that they do not interfere with the proper seating of the overlay
upon the dentition.
[0096] To generate the overlay, the dental professional may begin by
identifying on the superimposed models the intersection boundaries at the
areas where the dentition of the first model protrudes beyond the dentition of
the second model, as shown at step S110 in FIG. 19. For example, FIG. 14
illustrates one intersection boundary 28 between the tooth 20 and the veneer
22. The modeling software may be programmed to identify these boundaries
and to highlight them for the dental professional. The portion 24 of the
dentition that extends outward from the intersection boundary 28 will be
removed by the dental professional during the prosthodontic procedure.
[0097] Once the intersection boundaries have been identified, a
preparation guide may be fabricated that substantially conforms to the second
model but includes apertures defined by the intersection boundaries, as shown
at step S112 in FIG. 19. An example of a preparation guide or overlay 30, for
a single tooth 20 is illustrated in FIG. 15. The overlay 30 includes a wall
portion 32 forming a cavity 34 configured to receive the tooth 20. The
preparation guide 30 includes an aperture 36 that corresponds to the
intersection boundary 28 shown in FIG. 14. The apertures 36 allow the
protruding portions 24 of the tooth 20, to extend through the aperture 36. The
protruding portions 24 thus to not interfere with proper seating of the guide
30
33
CA 02820539 2013-06-13
upon the tooth 20 in the configuration prior to removal of any tooth material.
Guide 30 may be placed over tooth 20 to quickly and efficiently identify
protruding portions 24 that are to be removed.
[0098] After placing the preparation guide 30 over the tooth 20 (step
S114 in FIG. 19), the dental professional removes the protruding portion 24
(step S116). FIG. 16 illustrates the tooth 20 after removal of the protruding
portion and with the preparation guide 30 still in place. Using the guide 30
over the tooth 20 as shown, the dental professional can remove the protruding
portion of the tooth 20 with greater precision as compared to a procedure
involving no overlay. The dental professional simply cuts or grinds down any
portions of the tooth 20 that extend beyond the overlay 30. The overlay 30
thus not only highlights the portions of the tooth 20 to be removed, but it
also
shields portions of the tooth 20 that are not to be removed, thereby
preventing
unnecessary tooth reduction.
[0099] If a dental restoration 22 is to be placed over the tooth 20, the
dental professional also removes portions 26 of the tooth 20 in order to
create
space for the veneer 22, as shown in FIG. 16 and at step S118 in FIG. 19. The
dental professional may use the guide 30 to ensure that the removed tooth
portions provide adequate thickness for the veneer 22. For example, the dental
professional may place the guide 30 over the tooth 20 as shown in FIG. 16,
perforate the guide 30, and measure with a probe the distances between the
tooth 20 and the inner surfaces of the guide 30. When the tooth 20 has been
fully prepared, as shown in FIG. 17, the dental professional applies the
veneer
22, as shown in FIG. 18 and at step S120 in FIG. 19.
34
CA 02820539 2013-06-13
[00100] The guide 30 may be fabricated using any well known method
or suitable technique, for example, a rapid prototyping method or a molding
technique. During the fabrication process, the apertures 36 in the guide 30
may be produced as the guide 30 is formed, or they may be cut out of the
guide 30 after it has been formed.
[00101] A given guide may include just one aperture or a plurality of
apertures. The boundaries of the aperture(s) may be electronically determined
and the locations provided to cutting machinery to remove material at the
aperture locations. Alternatively, the borders of the aperture(s) may be
marked on the guide during the fabrication process so the dental professional
may cut out the material at the aperture locations himself. The marking may
be performed using ink and/or laser marking, for example.
[00102] Those of ordinary skill in the art will appreciate that the guide
30 described above may be used in conjunction with any of the methods
described above. For example, the guide 30 may be employed during step 522
shown in FIGS. 8 and 10. Alternatively, the guide 30 may be used in other
methods not disclosed herein. When used in conjunction with a method
including an orthodontic treatment plan and a prosthodontic treatment plan,
such as certain embodiments of the methods described above, the dental
professional may construct the guide 30 by superimposing the virtual model of
the patient's dentition in the intermediate configuration with the virtual
model
of the patient's dentition in the final configuration. Alternatively, the
dental
professional may construct the guide 30 by superimposing the virtual model of
the patient's dentition in the beginning configuration with the virtual model
of
CA 02820539 2013-06-13
the patient's dentition in the final configuration. Intersection boundaries of
the
two superimposed virtual models would define the locations of the apertures
36 in the guide 30.
Simulated Veneers
[00103] A simulated veneer may be generated automatically for all
orthodontic set-ups, including retrospective set-ups, such that a library of
models may be created systematically for the purpose of diagnosis and
screening for potential veneer cases. The automated models may be measured
in terms of, for example, volume, area and thickness, to better characterize
the
impact of veneer placement to the dentition prior, to initiating treatment.
The
simulated veneers allow doctors to avoid unnecessary movement of the teeth
and removal of excessive amounts of tooth structure.
[00104] In one embodiment, orthodontic and prosthodontic procedures
may be combined virtually to create simulated veneers. Using an orthodontic
procedure, a starting and stopping point for a veneering procedure may be
determined. Thus, a virtual simulated veneer may be created using a Final
alignment position relative to an Initial tooth position. Thus, the method
described uses three points of data: Initial position, simulated or actual
Prepared position (tooth material removed), Final alignment position (or any
other intermediate position).
[00105] The Initial and the Prepared positions are superimposed to
determine the difference in volume between the tooth in its Initial position
and
36
CA 02820539 2013-06-13
the tooth in the Prepared position. The difference represents the amount of
tooth structure removed (or needed to be removed). Thus:
Vr ¨ Vi Vp
where V1 is the initial tooth volume, Vp is the prepared tooth volume, and V,
is
the volume removed or preparation volume.
[00106] The Initial position and the Final alignment position may also
be superimposed relative to a reference to define a sweep path from the
Initial
position to the Final alignment position for each tooth. The reference may be
a static tooth, rugae, gingival and the like. The sweep path defines a swept
volume (V,), which represents the union of the prepared tooth volume and
restorative structure volume (restoration volume) that is to be created. The
swept volume may need to be modified to assure that the swept volume of the
tooth does not intersect the swept volume of a neighboring tooth or veneer.
[00107] The tool predicts the restoration volume (Vres) as follows:
Vres = Vs - Vp
where, the Vp is subtracted from the V, in order to create the total
restoration
volume, Vres
[00108] The Võõ V, ,Vp ,V, may all be formed as separate geometrical
models apart from the tooth. Using features of the tool, the Võ, (simulated
veneer), for example, may be manipulated through shape modification, as well
as color modification. The simulated veneer may also be printed as a physical
3-D graphic or formed as a 3-D solid model.
[00109] Advantageously, the veneer-related quantification may be used
as the reference for a veneering review, evaluation and analysis. The
37
CA 02820539 2013-06-13
quantification may include, but is not limited to, volume, thickness, area and
the like. The quantified results may be used to automatically or manually
select the optimal start point and stop point of a veneering treatment. In
addition, the ability to visualize the quantified results provides a reference
for
a doctor or patient to select the preferable veneering option. For example, as
illustrated in the graph of FIG. 20, the doctor and patient can determine the
optimal start and stop point, which yields the least amount of tooth mass
removal and/or mass build-up over a given amount of available treatment
time. Optimality also includes the probability of achieving the Final
alignment position for a given type of malocclusion in the available treatment
time. It should be understood that available treatment time equates to an
amount of tooth movement that may be realized during the available treatment
time.
[00110] FIG. 21 is a flowchart illustrating a process s2100 for
simulating the creation of veneers using orthodontic and prosthodontic
techniques. FIGS. 22A and 22B are simplified views of a dental arch in an
Initial position and in a Final alignment position, respectively.
[00111] Referring to FIGS. 21, 22A and 22B, in step s2102, the dental
professional, perhaps in conjunction with a dental laboratory, may create a
computer-generated, 3-D, virtual model of the patient's actual dentition in a
beginning configuration 2202 (FIG. 22A). The virtual model may be
generated prior to any tooth preparation, so that the model represents the
patient's dentition in a pretreatment state. Some processes for making such a
38
CA 02820539 2013-06-13
virtual model are described in, for example, the '207 publication and the '705
publication referenced above.
[00112] The dental professional as shown in step s2104, again perhaps in
conjunction with the dental laboratory or any other company or service/product
provider, may transform the virtual model of the beginning configuration. The
dental
professional may use virtual orthodontia to create a computer-generated, 3-D,
virtual
model of the patient's dentition in a Final alignment position or Final
configuration
2204 (FIG. 22B), which represents the desired "smile" or design goal that the
patient
and doctor desire. The virtual orthodontia may include manipulation and
movement of
teeth in the virtual model. The orthodontic treatment may also include the
modeling of
several intermediate stages between the beginning configuration and Final
alignment
position. The beginning configuration or else one of the intermediate stages
may be
considered an Initial position for starting the veneering treatment as will be
explained
below.
[00113] In step s2108, a tentative restoration volume (simulated veneer) may
be
calculated for a given time available for treatment. FIG. 23 illustrates an
embodiment
for calculating the tentative restoration volume of step s2108.
[00114] Referring now to FIG. 23, one embodiment of the present methods may
begin when a patient first consults a dental professional regarding an
orthodontic
procedure and/or a prosthodontic procedure (s2302). During the initial
consultation, the
dental professional and the patient may discuss the patient's treatment
goal(s) and any
constraints that might limit the time available for treatment. For example,
the patient
may desire to have his
39
CA 02820539 2013-06-13
or her smile enhanced, but has only a six-month window of opportunity for
treatment. In this situation, the timeframe for treatment is limited, and an
appropriate orthodontic/prosthodontic treatment plan must be set to fit within
the timeframe.
[00115] In the present embodiment, the dental professional may decide
that substantially the entire six-month window of treatment time be used to
provide a particular amount of tooth movement before starting the veneering
treatment. Accordingly, in step s2304, the dental professional, again perhaps
in conjunction with the dental laboratory or any other company or
service/product provider, simulates orthodontic movement of the teeth
between the beginning configuration and an Intermediate position.
[00116] In the present embodiment, the Intermediate position represents
the starting point or the Initial position for the veneering treatment and is
so
specified (s2306). Now that the dental professional knows the predicted
Initial
position of the teeth, the dental professional may determine the Prepared
position.
[00117] In step s2308, the dental professional, again perhaps in
conjunction with the dental laboratory or any other company or
service/product provider, may transform the virtual model of the Initial
position using virtual prosthodontia to create a computer-generated, 3-D,
virtual model of the patient's dentition in a Prepared or cut configuration.
The
virtual prosthodontics may include the tooth mass removal that the dental
professional deems necessary to achieve the design goal (the desired "smile").
CA 02820539 2013-06-13
The initial Prepared position is referred to hereinafter as the tentative
Prepared
position.
[00118] In step s2308, the dental professional may quantify the amount
of tooth mass to be removed from the dentition to achieve the desired smile.
Referring to FIG. 24, in one embodiment, Intermediate tooth 2402 and
Prepared tooth 2404 are superimposed to determine Prepared region 2406,
which is the difference in volume between Intermediate tooth 2402 and
Prepared tooth 2404. Prepared region 2406 represents the amount of tooth
structure to be removed (Vr).
[00119] Referring again to FIG. 23, in step s2310, the dental
professional may superimpose the teeth in the Intermediate position with the
teeth in the Final alignment position to define a sweep path from the
Intermediate position to the Final alignment position for each tooth to be
veneered. For example, FIG. 25 is a side view and top view of Prepared tooth
2404 where the swept volume Vs is shown. In this embodiment, swept volume
Vs is the space occupied by moving a geometric model of Prepared tooth 2404
along a path from the Intermediate position to the Final alignment position.
[00120] Reference is made to the swept volume in the embodiments
described, however, one of ordinary skill in the art will understand that many
well-known numerical algorithms exist that may be used to generate the
envelope model of the Intermediate position and the Final alignment position.
For example, such algorithms are referred to as the marching cube, convex
hull, maxima, and Boolean union operations. In addition, the swept volume
may be estimated analytically.
41
CA 02820539 2013-06-13
[001211 In step s2312, simulated veneers are generated as separate
geometric models apart from the Prepared tooth.
[00122] In step s2314, the simulated veneer may be evaluated by
reviewing the quantified measurements and visualizing the final geometry of
the simulated veneers. For example, Preparation region 2406 is calculated
which represents the amount of tooth structure to be removed in preparing the
teeth. Also, the total restoration volume is calculated by subtracting the
Prepared tooth volume from the sweep volume to create the total restoration
volume. The simulated veneers may be visualized to facilitate any shape
modification, color modification or any other modification that the dental
professional deems appropriate.
[00123] Referring again to FIG. 21, once a tentative restoration volume
has been calculated (s2108), a decision is made in step s2110 as to whether
the
restoration volume is acceptable to the dental professional and/or the
patient.
In some cases, for example, the dental professional or patient may decide that
the restoration volume is too large or that the amount of tooth structure
required to be removed is too great. In these cases, the process may return to
the orthodontic simulation step s2104 where the dental professional attempts
to modify the design goal, which may include manipulating the movement of
the teeth to lessen the concerns of the dental professional and patient.
[00124] In cases where the tentative restoration is acceptable, the
process continues to step s2112, where a check is made to determine if the
swept volume may need to be modified to assure that the sweep volume of the
tooth does not overlap the swept volume of a neighboring tooth or veneer.
42
CA 02820539 2013-06-13
[00125] In step s2114, if overlap does exist, the overlap needs to be
resolved. One approach to remove the overlap is to deform or locally modify
the overlap area of the veneer model.
[00126] In step s2116, if there is no overlap, the tentative restoration is
deemed to be the final restoration and may be subsequently made into an
actual restoration.
[00127] Referring now to FIG. 26, as shown in step s2602, to create an
actual restoration from the final restoration, a veneer template may be
selected
from a veneer library, which includes all types, shapes and sizes of veneers.
The veneer template provides a reference geometry for the modeling of the
actual restoration. The reference geometry of the veneer template may be a
3D digital model. Generally, the veneer template may be defined by various
physical parameters, such as height, width, thickness and the like.
[00128] As shown in step s2604, after a veneer template has been
selected, the veneer template may be used to generate the actual veneer shape
model (actual restoration) by deforming the veneer template to approximate
the final restoration model. When the physical parameters of the veneer
template are changed, the geometry of the actual restoration changes. The
deformation may be achieved through the adjustment of the physical
parameters, 3D morphing and the adjustment of the control points on the
template surface.
[00129] As shown in step s2606, after the actual veneer shape model is
generated, if necessary, the actual veneer shape model may be further locally
43
CA 02820539 2013-06-13
modified automatically or interactively to satisfy any clinical requirements
and
user preferences.
[00130] Once the actual veneer shape model, with any modifications,
has been generated, it may be made into a physical veneer. In one
embodiment, the physical veneer may be created by creating the reverse
veneer with a template, filling the template with a dental material, such as
acrylic, composite, silicone, and the like, in the uncured state and then
curing
the dental material, creating the physical veneer in the desired shape. In one
alternative embodiment, the physical veneer may be built up directly in wax
with a 3-D printer. The wax may then be invested and cast into, for example,
porcelain or glass, using the lost-wax technique. In another alternative
embodiment, the physical veneer may be converted directly into a CAD-CAM
object that may be milled from a block of porcelain or glass.
[00131] The flowcharts provided herein illustrate example embodiments
of the present methods. In some alternative embodiments, the steps shown in
one or more figures may occur out of the order presented. For example, in
some cases, two steps shown in succession may be executed substantially
concurrently, or the steps may sometimes be executed in the reverse order.
Those of ordinary skill in the art will also appreciate that the scope of the
present methods is defined only by the claims provided below, and therefore
some embodiments may not include all of the steps shown in the figures.
[00132] The above description presents the best mode contemplated for
carrying out the present prosthodontic and orthodontic apparatus and methods,
and of the manner and process of making and using them, in such full, clear,
44
CA 02820539 2013-06-13
concise, and exact terms as to enable any person skilled in the art to which
it
pertains to make these apparatus and use these methods. These apparatus and
methods are, however, susceptible to modifications and alternate constructions
from those discussed above that are equivalent. Consequently, these apparatus
and methods are not limited to the particular embodiments disclosed. On the
contrary, these apparatus and methods cover all modifications and alternate
constructions coming within the spirit and scope of the apparatus and methods
as generally expressed by the following claims, which particularly point out
and distinctly claim the subject matter of the apparatus and methods.
