U.S. patent application number 14/214178 was filed with the patent office on 2014-07-17 for interactive dental restorative network.
This patent application is currently assigned to IVOCLAR VIVADENT AG. The applicant listed for this patent is IVOCLAR VIVADENT AG, SHADE ANALYZING TECHNOLOGIES, INC.. Invention is credited to Robert A. GANLEY, Maryann LEHMANN.
Application Number | 20140200865 14/214178 |
Document ID | / |
Family ID | 39126624 |
Filed Date | 2014-07-17 |
United States Patent
Application |
20140200865 |
Kind Code |
A1 |
LEHMANN; Maryann ; et
al. |
July 17, 2014 |
INTERACTIVE DENTAL RESTORATIVE NETWORK
Abstract
The invention relates to a method for assisting a dental
practitioner in the dental restoration of a patient treatment area.
The method includes forming a three-dimensional (3D) model
represented in digital form of the treatment area to be restored,
the model being formed during a first visit by the patient to a
dentist's office; developing a preliminary treatment plan including
a prostheses specification that is based, at least in part, on the
3D digital model of the treatment area; storing the 3D digital
model and the preliminary treatment plan in a database along with
the patient's record; and conferencing with other practitioners in
order to determine whether the preliminary treatment plan is
appropriate for the patient based on the dental data.
Inventors: |
LEHMANN; Maryann; (Darien,
CT) ; GANLEY; Robert A.; (Williamsville, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
IVOCLAR VIVADENT AG
SHADE ANALYZING TECHNOLOGIES, INC. |
Schaan
Darien |
CT |
LI
US |
|
|
Assignee: |
IVOCLAR VIVADENT AG
Schaan
CT
SHADE ANALYZING TECHNOLOGIES, INC.
Darien
|
Family ID: |
39126624 |
Appl. No.: |
14/214178 |
Filed: |
March 14, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11513273 |
Aug 31, 2006 |
|
|
|
14214178 |
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Current U.S.
Class: |
703/1 ;
700/98 |
Current CPC
Class: |
A61B 6/14 20130101; A61C
13/0004 20130101; G16H 80/00 20180101; A61C 9/0053 20130101; G16H
40/67 20180101; G06F 30/00 20200101; G16H 20/40 20180101; G16H
10/60 20180101; G16H 30/20 20180101 |
Class at
Publication: |
703/1 ;
700/98 |
International
Class: |
G06F 17/50 20060101
G06F017/50; A61B 6/14 20060101 A61B006/14; A61C 9/00 20060101
A61C009/00 |
Claims
1. A method for assisting a dental practitioner in the dental
restoration of a patient treatment area comprising: forming a
three-dimensional (3D) model represented in digital form of the
treatment area to be restored, the model being formed during a
first visit by the patient to a dentist's office; developing a
preliminary treatment plan including a prostheses specification
that is based, at least in part, on the 3D digital model of the
treatment area; storing the 3D digital model and the preliminary
treatment plan in a database along with the patient's record; and
conferencing with other practitioners in order to determine whether
the preliminary treatment plan is appropriate for the patient based
on the dental data.
2. The method of claim 1 wherein the preliminary treatment plan and
prostheses specification are developed during consultation between
the dentist's office, a dental laboratory, and a further dental
professional, with the database being simultaneously accessible by
each party during the consultation by means of a communication
network.
3. The method of claim 1 further comprising designing a dental
prosthesis by means of computer-aided-design facilities that have
access to the database, the prosthesis design being based, at least
on part, on the preliminary treatment plan including the prosthesis
specification and on the 3D digital model.
4. The method of claim 3 further comprising fabricating the dental
prosthesis by means of computer-aided-manufacturing facilities that
have access to the database, the prosthesis fabrication being
based, at least on part, on the prosthesis design.
5. The method of claim 4 wherein the preliminary treatment plan
including a prosthesis specification is presented to the patient
during the same first patient visit to the dentist's office and the
prosthesis is fabricated in the dentist's office during the same
first patient visit to the dentist.
6. The method of claim 1 further comprising simulating the course
of treatment, the simulation including images of the stages of
treatment.
7. The method of claim 1 wherein the plurality of dental
practitioners further comprises appropriate combinations of an
orthodontist, an oral surgeon, a dental specialist, a dental
restoration manufacturer, a technical sales rep, an authorized
user, and the patient.
8. The method of claim 1 wherein the communications network
provides communication among appropriate combinations of a dental
office, a dental specialist's office, a prosthetic laboratory, a
dental laboratory and a dental restoration manufacturer.
9. The method of claim 1 which further comprises implementing one
or more applications that displays the patient's dental data and
record and provides direct communication over the Internet between
the dentist and at least one other practicioner with respect to the
restorative needs of the patient.
10. The method of claim 9, wherein the dental data comprises one or
more of a patient's dental records, an x-ray of a patient's tooth
preparation, a digital image of a patient's tooth preparation, or a
video image of a patient's tooth and is made available to the
practitioners in real time.
11. The method of claim 9, wherein the dentist accesses the dental
data via a client application on his computer and the laboratory
accesses the dental data via a client application on its computer,
with each application comprising a web browser.
12. The method of claim 9, wherein the storing of the dental data
and patient record is over the Internet and the dentist and
laboratory each have simultaneous access to the image and patient
record.
13. The method of claim 12, wherein the direct communication is
performed in conjunction with having simultaneous access to the
patient record or the image.
14. The method of claim 9, which further comprises providing a
server at the dentist's office or dental laboratory for storing the
dental data and patient record.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a division of application Ser. No.
11/513,273 filed Aug. 31, 2006, which is incorporated herein by
reference thereto.
TECHNICAL FIELD
[0002] The invention is directed to methods, systems and devices
for dental restoration wherein communication between the dentist
and restoration laboratory are held in real time to discuss,
finalize and optimize a treatment plan for a patient. More
specifically, the invention is directed to an interactive
computer-based system and method to enable the dentist and
restoration laboratory to analyze color images of one or more teeth
and teeth preparation so that a replacement tooth or crown can be
particularly designed to precisely match the tooth that is to be
replaced in certain clinical or cosmetic procedures.
BACKGROUND OF THE INVENTION
[0003] Restorative dentistry is the art and science of replacing or
restoring lost tooth structure. The amount of tooth structure to be
replaced determines what path the operator takes--whether the
restoration will be a crown, bridge, inlay, onlay or direct
restoration (i.e. a filling). The choice of that path in the past
was more simple, due to the limited number of materials and
techniques available. For example, U.S. Pat. Nos. 5,766,006 and
5,961,324 describe methods and systems for determining tooth color
information based upon digital images provided by a camera and then
matching the color of the restoration article (i.e., dental
prosthesis) with the determined tooth color. In recent years,
however, with the advent of new materials and concepts, treatment
choices have expanded in a phenomenal way. Dentists are now facing
an overload of information in trying to decide which materials and
procedures are the best suited for their particular cases. What the
state-of-the-art practitioner needs is a source to be able to go
to, at a moment's notice, that will be able to aid him and his lab
if necessary in treatment planning and delivering the best
restorative dentistry possible, utilizing the most appropriate
materials available today. The present invention now satisfies this
need.
SUMMARY OF THE INVENTION
[0004] The invention relates to a computer-based dental restoration
system between a dentist and a practitioner. The system includes a
network server having a database for storing digital
representations, and a communications network providing access to
the network server and facilitating direct communication at least
between a dentist and a practitioner. The system further includes
one or more computers for accessing digital representations over
the communications network and displaying the digital
representations in a humanly readable format. Preferably, the
practitioner includes one or more of a dentist, a dental
specialist, and a dental restoration manufacturer.
[0005] Generally, the digital representations includes one or more
of a patient's dental record or aspects thereof, an x-ray of a
patient's tooth, a digital image of a patient's tooth, a video
image of a patient's tooth, or a preliminary dental treatment plan.
The digital representations further include a digital impression
which is a three dimensional model of a treatment area. An
intraoral scanner is a preferred method for forming this three
dimensional model, but other means, such as, scanning of a dental
cast can also be used to obtain a digital impression. The digital
impression generally is operated on by an application running on at
least one of the one or more computers to provide a particular
functionality for the dentist or practitioner.
[0006] Advantageously, the one or more computers include a client
application that provides access to the database. The client
application generally includes a Web browser. At least one of the
one or more computers, the server, or both include a loading
application that loads the digital representations into the
database and another application that provides access to the
database via e-mail.
[0007] In the preferred embodiment, the one or more computers
provide the dentist and practitioner simultaneous access to at
least one of the digital representations, and in a further
embodiment, simultaneously perform direct communication. The
computer is a desktop or laptop device, a PDA or Blackberry device
or a cellular telephone and the communications network includes the
Internet.
[0008] In another preferred embodiment, the computer-based dental
restoration system provides real-time access to the network server
and the database further includes information about materials,
procedures, preparations concerning dental restoration prostheses.
In this embodiment, the communications network transfers voice,
video, and data between a dentist and practitioner. Preferably, the
communications network is configured to enable the dentist to
communicate a prostheses specification, consult with the
practitioner, obtain cost and viability options for presentation to
a patient, and place an order with the practitioner, wherein
elapsed time for the whole process is less than four hours. More
preferably, the elapsed time is less than one hour.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] These and other aspects of the invention should be more
apparent from the following detailed description and drawings in
which:
[0010] FIG. 1 illustrates a shade analyzer system for capturing
images in accord with a specific embodiment of this invention;
[0011] FIG. 2 shows a representative image captured by the system
of FIG. 1;
[0012] FIG. 3 shows a representative image made up of pixels as
captured by detector elements of the system in accord with the
invention:
[0013] FIG. 4 illustrates processing of the image of FIG. 3 using
pseudo-pixels, in accord with one preferred embodiment of the
invention;
[0014] FIG. 5 shows an end piece constructed for use with the
system in FIG. 1, for simultaneous processing of an actual tooth
image and various reference tooth shades;
[0015] FIG. 6 illustrates a compression sleeve constructed
according with a specific embodiment of the invention for capturing
high-quality tooth images;
[0016] FIG. 7 illustrates a source-to-tooth illumination, for
improved image capturing in accord with one embodiment of the
invention:
[0017] FIG. 8 illustrates baffling and stray-light rejection within
a sleeve in a specific embodiment of the invention;
[0018] FIG. 9 illustrates different pseudo-pixel imaging
mechanisms, optionally dependent upon tooth shape characteristics,
used in accord with the invention;
[0019] FIG. 10 illustrates a non-contact tooth imaging system, with
stray light rejection, constructed according to a specific
embodiment of the invention:
[0020] FIG. 11 illustrates another embodiment of a non-contact
tooth imaging system in accordance with the present invention;
[0021] FIG. 12 illustrates a digital image of a tooth:
[0022] FIG. 13 illustrates a system for reimaging a tooth;
[0023] FIG. 14 illustrates various tooth decay patterns and
restorations that can be addressed in accordance with the present
invention;
[0024] FIG. 15 is a schematic representation of the interactive
network system of the invention; and
[0025] FIG. 16 is a block-diagram of the configuration of the
interactive network system of the invention;
[0026] FIG. 17 illustrates an embodiment of Web application
components of the interactive network system of the invention;
[0027] FIG. 18 illustrates an embodiment of Web page layout of the
interactive network system of the invention;
[0028] FIG. 19 is a flow diagram depicting operational process of
the interactive network system of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0029] The invention relates to an interactive dental restoration
method between a dentist and a dental restoration laboratory. The
basic steps of this method include identifying a dental restoration
need in a patient; designing a preliminary treatment plan that
includes design criteria for preparation of a dental prosthesis to
be placed in the patient to satisfy the dental restoration need;
transmitting the preliminary treatment plan via a communications
network to a dental restoration laboratory; and communicating a
final treatment plan, including modifications to the preliminary
treatment plan where necessary, to the dentist. Typically, the
final treatment plan includes information about materials for
preparing a dental prosthesis that satisfies the design criteria,
and the dental prosthesis is then prepared for placement in the
patient. This method enables optimization of the dental restoration
with significant savings in time and effort for the dentist, dental
technician and the patient.
[0030] Generally, the dentist prepares the preliminary treatment
plan and the design criteria include digital image representations
of the dental restoration need. Thereafter, the preliminary
treatment plan can be forwarded to and evaluated by the laboratory
before a final treatment plan is formulated and communicated to the
dentist. The step of transmitting and evaluating the plan are
codirected over the communications network. Thus, the final
treatment plan is not implemented in the patient until after
interim preparation information is transmitted to the laboratory
and confirmed, thus avoiding rework or revision after the plan has
been implemented.
[0031] Advantageously, the design criteria or the modifications
thereto include proposed decay excavation, tooth preparation, or
dental prosthesis color. When a dental prosthesis such as a crown,
bridge or replacement tooth is needed, the method includes
verifying that the dental prosthesis is prepared according to the
final treatment plan prior to placement of the dental prosthesis in
the patient. In order to obtain the best color match of the dental
prosthesis with the patient's teeth, the digital image
representations include REAL IMAGE and REFERENCE IMAGES and the
modifications include correlation of a color selection for the
dental prosthesis to match the REAL IMAGE. Furthermore, the design
criteria can include tooth preparation and proposed decay
excavation, and the method further comprises a communication of a
confirmation or modification, from the laboratory, of the
acceptability of one or more of the proposed design criteria.
[0032] The invention also relates to a computer-based dental
restoration system comprising a network server having a database
storing information about materials, procedures and preparations
concerning dental restoration prosthesis: a communications network
providing access to the network server; and one or more computers
at a dental office accessing information stored at the database
over the communications network and displaying the information in a
humanly readable format. Preferably, the communications network is
the Internet, and the information stored in the database comprises
preparation diagrams, reduction dimensions, margin design and burs
for specific dental restoration prostheses.
[0033] Advantageously, the database further stores information
concerning one or more patients having dental restoration needs.
Also, the network server further comprises application programs for
enabling users to query the database regarding specific materials
or procedures concerning dental restoration prostheses for
confirmation, verification, modification or evaluation of the same,
with the one or more computers at the dental office receiving
answers from the database to such queries. If desired, a printer
located at the dental office can be used to print these answers for
use by the dentist in carrying out the treatment plan.
[0034] The dental restoration laboratory also includes at least one
computer that has access to the network server and the computer(s)
at the dental office over the communications network. Preferably,
the system includes a digital camera for taking digital images of
the patient's teeth that are in need of dental restoration and a
communication link for transmitting the digital images to the
computer(s) at the dental office. Also, the computer(s) at the
dental office store these digital images and the communications
network forwards the digital images to the database for storage
therein.
[0035] The present invention further provides an enhanced dental
restoration network as a service for dentists. This network would
be established via a computerized link between the dentist, the
lab, and, optionally, the lab's databank of the most current
information regarding materials, procedures, and other services
such as preparation design and surveying for dental restoration
prostheses such as caps, crowns, bridges, fillings and the
like.
[0036] In a typical case, initial steps of complete examination and
diagnosis of the patient's dental condition is by the dentist. This
generally includes a basic periodontal examination, clinical exam,
radiographs, screening for TMD, etc. The dentist also creates a
preliminary treatment plan for addressing the dental needs of the
patient. When tooth capping or replacement is required, clinical
pictures which can are taken and captured on a program and are
forwarded to the lab. Theses pictures can be of the color of the
patient's teeth, the preparation of a tooth for further treatment,
or even of a temporary treatment which can be modified or enhanced
before being finalized. The pictures can be taken in any one of a
number of ways, as described in more detail below.
[0037] In this invention, an on-site advanced restorative system is
provided where the dentist takes one or more digital images of the
tooth prior to restoration, eliminates areas of decay in the image,
and matches the shade of material to be used to restore the tooth
based upon the digital images of the tooth prior to removal. In
another aspect, the dentist takes digital images of the tooth after
preparation and matches the shade of the material to be used in
restoration based upon the remaining parts of the tooth. These
pictures can be forwarded by facsimile, direct computer link, or by
e-mail to the lab for evaluation, along with the dentist's
preliminary treatment plan.
[0038] After preliminary treatment plans are designed, and areas
such as periodontal needs, decay excavation, endodontic concerns
are addressed, the restorative needs are considered. If the
treatment plan may include fixed prosthodontics (crowns and
bridges), the clinical pictures are then forwarded to the lab. The
doctor and technician assess the case together prior to accessing
the interactive dental restorative network ("the site"). An
illustration of such a network is shown in FIG. 16 and described in
more detail below. If the case involves only direct restorations,
the dentist can go directly to the site.
[0039] If the dentist does not have access to the site but his lab
does, the doctor could send pictures to the lab, the technician in
turn could access the site, and consult back to the doctor giving
restorative options as given by the site. This service would be
rendered by the labs for dentists that are not comfortable or
familiar enough with computers to do their own electronic
processing and communication with the site.
[0040] The site would provide access for users to obtain
information on materials, procedures involved in using such
materials such as preparation design, recommended burs to achieve
such a preparation, recommended temporization materials, cements
that should be used with that given material, instructions on how
to use such a cement (i.e., conditions such as whether one should
etch or prime, for how long, whether to dry it or not, to pre-cure
it or not, etc.), and where to buy such materials. Alternatively,
the lab could explain how it would provide such a service or who
the dentist could contact to obtain such service. Beyond this, once
the treatment is underway, the dentist could verify his preparation
with the technician, if necessary, by sending digital images
electronically for review prior to final impressions. For a more
precise evaluation of the case in treatment, the dentist would scan
his preparations and go to the part of the site that would survey
the teeth and assess reduction amount. This would typically be used
in larger and more complex cases.
[0041] The site would offer a number of features for communicating
dental restoration data to the dentist and technician. One of the
most unique features of the site is that it is interactive. Rather
than just being a databank of information for the dentist to
review, the dentist would be led through a step by step procedure
to determine the most appropriate restorative path to take. The
site could be visited periodically to consider alternative
procedures, different options or to just confirm that the previous
recommendations are clear and are being followed. Although many
dentists read articles and reports, and attend seminars to obtain
the latest information, until there is a case in hand, a lot of
that information is not applicable. By the time a given case
corresponds to a case presented at a previous seminar, the dentist
may have already forgotten the information. The present method and
system provides immediate feedback of the most up-to-date
information in real time for the specific need of the current
patient.
[0042] As the dentist accesses the site, he can immediately be
asked certain questions regarding the patient's history. Typical
questions under consideration for dental restoration procedures
include: Are esthetics a main concern? Is the patient a bruxer
(i.e., heavy grinder)? What is the extension of the patient's
smile--give the teeth numbers of the limits of what is visible on
their widest smile? Does the patient have a high lip line, i.e.,
does their lip lie below the incisal edge, midtooth, at the
cervical margin, above the cervical margin? Do they show mandibular
(lower) teeth when they smile? Is the opposing occlusion natural?
If not, is it metal, porcelain, amalgam, composite or denture
teeth? By providing the restoration lab with this additional
information, all factors can be considered so that a sound,
tailored treatment plan can be confirmed or recommended.
[0043] The laboratory then would consider the teeth in question:
Are they anterior or posterior?Endodontically treated or vital?What
shade are they initially?What is the desired shade?What is the
prepared tooth shade?What are the dimensions of the tooth--is it a
short clinical crown, or average to larger than average in size?
Are there any implants involved? The process would operate like an
"elimination tree"--if the first question of esthetic concern was a
"no", the site would not go on to ask smile dimensions and such.
All questions would be answered to a point to compile a profile,
and any given patient may require their case to be divided into
more than one profile depending on the scope of their needs, say
corresponding to sections of their mouth in quadrants.
[0044] Another issue to be addressed is that of materials. This
would give the material name, its characteristics and properties,
and why it was suggested. Suggested is the operative word here
because it should be understood that ultimately it is the dentist's
choice of treatment modality that is used and not that of the
technician or the site. After the dentist chooses the material, he
would need to know where to obtain it, if he didn't already have
access to it. This would entail the dentist purchasing a direct
material, either through the site to an ordering area, or being
referred to a lab in his area that uses such a system.
[0045] The issue of preparation design when planning to use that
given material is also addressed by the site. Different materials
demand different substructures and margins. There are not a
tremendous number of different designs needed. Within the site,
there is a file of preparation diagrams, which could be printed out
by the dentist, if necessary, to provide reduction dimensions,
margin design and the burs needed to do this. This would include
bur name and number, type and where to obtain them. Once again, the
dentist may order this through the site or obtain information on
where it could be purchased in his area. The dentist could simply
obtain all materials from the site, compile a shopping list for
this particular procedure and go out and obtain the materials on
his own.
[0046] Once the case is underway, and the initial preparations are
completed, the dentist could go back to the site and scan the
preparations to assure compliance. Alternatively, digital
representations of the preparations could be sent back to the site
or lab for their further review. A review of the preparations can
also be made by accessing a survey area of the site. This would
evaluate the preparation for undercuts, under-reduction, margin
extension, and highlight areas that needed to be modified for
optimum results.
[0047] Communication with the site in real time would save a great
amount of time and effort. By first confirming that the
preparations and recommended dental restoration procedures are
correct, the lab would not have to be pouring and working on models
of a case that were not useable because the preparations required
changing. Also saved would be the time of having the patient return
to the office on multiple occasions for refining preparations. This
is a significant benefit for dentist, patient and laboratory. By
providing the laboratory operator with such information without
taking an impression, pouring up models and surveying them with a
traditional surveyor, both time, materials and expenses due to
re-work are saved.
[0048] Another advantage of real time evaluation is reduction. One
of the most common errors in preparation is under-reduction (i.e.,
not removing enough tooth structure to allow room for the materials
that will make up the crown or restoration), which causes either
too thin of restoration in that area which can lead to future
failure, or repreparation (i.e., more wasted chair time) and new
impressions or reduction copings. Within the survey site, the
dentist would be able to more accurately scan the preparation with
the teeth in occlusion so as to measure the amount of reduction to
the tenth of a millimeter. Then, the dentist would compare this
measurement to the given specifications of the preparation he had
retrieved earlier from the preparation design area of the site to
confirm compliance.
[0049] Another use of the present interactive dental restoration
network is the verification of the final dental prosthesis before
it is permanently placed in the patient's mouth. For example, when
a crown is finally prepared, digital images can be taken and
compared to the digital images of the patient's teeth that were
previously obtained to assure that the closest color match has been
achieved. Any necessary color corrections can be made by the
laboratory or the technician before permanent placement of the
crown. This again saves time by avoiding rework when the patient
returns to the dentist's office for the installation of the
crown.
[0050] A number of different aspects of determining tooth shade
color are disclosed. For clarity of presentation, these aspects are
organized and described below in sections which are not intended to
be limiting in any way.
The Color Determination Method
[0051] With reference to FIG. 1, a solid state camera 12 (e.g., a
CCD camera coupled to a PC board, or an intra-oral camera) is
utilized to capture one or more images of each known conventional
tooth shade. Tooth shades used to this end may correspond, for
example, to the VITA.TM. Shade guide, or a shade guide
corresponding to porcelain by another dental products manufacturer.
By way of example, a first series of images taken in accordance
with the invention corresponds to sequential images of the A1 shade
by Vita, a second series of images corresponds to sequential images
of the A2 shade by Vita, and so on. In accordance with the
invention, captured image series of the known tooth shade guides
are properly labeled and then stored onto the hard disk of the
computer, or other suitable storage device for further analysis.
FIG. 2 illustrates a representative digital image 30 captured by
the camera 12.
[0052] As known in the art, each digital image has a plurality of
picture elements, i.e., "pixels", corresponding to the elements of
the solid state camera and representing the light intensity and
color properties of a given spatial location on the tooth. The
distance between adjacent pixels in the image is determined by the
spatial resolution of the camera. For example, an image of a tooth
shade (or a human tooth) can be made up of 300 pixels in width
across the tooth and 350 pixels in height. In human teeth, any
given tooth is approximately the same size, give or take a couple
of millimeters, for all people. For example, most central incisors
usually measure between 9-11 mm in width, and somewhat greater in
length. It is clear therefore that for a given spatial resolution
of the camera, in accordance with this invention an image of a
tooth can be taken knowing the approximate number of pixels
corresponding to the tooth in the image. Thus, in the example
above, 1 mm of the tooth width may be represented by 30 pixels. It
will naturally be appreciated that the tooth image is typically not
rectangular, and that pixels at the corners 41 of an image may
correspond to the background (i.e., the region outside of the
tooth) and not of the tooth or tooth shade. See FIG. 2 for further
illustration.
[0053] As indicated above, a single digital image can be captured
for each tooth shade or actual tooth. Those skilled in the art will
appreciate, however, that taking a series of images per shade is
preferable, since it reduces the risk of image anomalies, as
explained in further detail below.
[0054] Next, each image or each image in a series is processed into
a "pseudo" reference image (hereinafter PSEUDO IMAGE) made up of
pseudo-pixels. As used in this disclosure, pseudo-pixels correspond
to groups of pixels covering specific areas (e.g., rectangular or
square) of the image plane. FIG. 3 shows a blow up image of the
pixels 42 (only representative pixels 42 are shown) which make up
the tooth image 40 of FIG. 2. In accord with the invention, these
pixels are transformed into pseudo-pixels 44, as shown in FIG. 4.
In the embodiment illustrated in FIG. 4 each pseudo-pixel 44 is
made up of all or some of the real pixels within the area of the
associated pseudo-pixel. Pseudo-pixels 44b shown in the figure
illustrate, for example, how a pseudo-pixel can be generated from
nine real pixels 42. FIG. 4 also illustrates that an image can be
made from either a real tooth 40 (resulting in a REAL IMAGE) or a
reference shade 40 (resulting in a REFERENCE IMAGE).
[0055] FIG. 9 shows how pseudo-pixels can be arranged in a
preferred embodiment in different patterns, automatically,
depending upon which tooth is imaged. For example, an incisor 200
can have an arrangement of pseudo-pixels 202, as shown in the
left-hand example, while a molar 204 can have an arrangement of
pseudo-pixels 206, as shown in the right-hand example. With further
reference to FIG. 1, such arrangements can be made automatically in
the system of this invention by informing the computer 14, and
hence the software 50, to apply pseudo-pixels in the appropriate
pattern. Such arrangements assist in overall processing by ensuring
appropriate pseudo-pixel placement. As illustrated in FIG. 9,
pseudo-pixels need not be contiguous, or aligned, such as shown by
the arrangement of pseudo-pixels 206.
[0056] In a preferred embodiment, the intensity and color
associated with a pseudo-pixel are computed or otherwise formed as
an average (or other statistical measure) of the actual pixels
forming the pseudo-pixel. By way of example, if an actual image
taken in the first step of the method corresponds to a rectangular
tooth that is digitized at 300 W by 350 H resolution, i.e., having
a total of 300.times.350 elements, in accordance with this
embodiment one can create pseudo-pixels such as 6 W by 7 H, with
each pseudo-pixel being formed as a statistical measure of the
50.times.50 pixels within the pseudo-pixel (resulting in 42
pseudo-pixels representing the entire tooth).
[0057] As noted above, in accordance with a preferred embodiment,
pseudo-pixels are generated by data derived from all or some of the
actual pixels located within the pseudo-pixel. For example, in a
specific embodiment one can average the red, green and blue (RGB)
components for each of the 2500 pixels within each pseudo-pixel to
determine a reference RGB for that pseudo-pixel. Those skilled in
the art will appreciate that other statistical measures or
characteristics can be used, such as the mean "hue" measure of the
pixels within a pseudo-pixel, or others. For example, the RGB pixel
values may be converted into the Hue, Saturation and Intensity
("HSI") color space by using known algorithms, such as the Gonzalez
and Woods method, as follows:
[0058] R=Red value for pixel
[0059] G=Green value for pixel
[0060] B=Blue value for pixel
[0061] Intensity=1/3 (R+G+B)
[0062] Saturation=1-(3/R+G+B))*Min(R, G, B)
[0063]
Hue=Cos.sup.-1((0.5*((R-G)+(R-B)))/((R-B)*(G-B)).sup.0.5)
[0064] If S=0, Hue is meaningless
[0065] If (B/Intensity)>(G/Intensity) then Hue=360-Hue
[0066] RGB corresponds generally to three different pixels
[0067] Since Hue is an angle in degrees values were normalized to
0.1 with Hue=Hue/360
[0068] As known in the art, the RGB color space can be represented
as a simple cube, with R, G and B emanating from one corner along
three perpendicular edges. The origin corner (0,0,0) is black, and
the opposite corner (1,1,1) is white. All points along this line
from corner to corner are shades of grey. The HSI color space is
this same cube stood on the origin corner, with the Black White
line being vertical. The black-white line is the intensity axis,
the hue is given by an angle from the intensity axis and the
saturation is the distance from the intensity axis to the color
point (i.e., the radius). The new VITAPAN 3D-Master Shade system
uses an L*a*b* Color Sphere to determine tooth shades based on
Value, Chroma and Hue. It is possible to convert the RGB values to
this color system, if necessary or desired.
[0069] In accordance with a preferred embodiment, PSEUDO IMAGES are
processed then into a "REFERENCE IMAGE". By way of example, the
REFERENCE IMAGE is generated as an average (or other statistical
measure) of the PSEUDO IMAGE series of images of the VITA.TM. A2
shade guide. The measure in this example is obtained by averaging
the R, G, B components for each pseudo-pixel of the A2 PSEUDO IMAGE
series to determine an average RGB value for a pseudo-pixel of the
REFERENCE IMAGE. In alternative embodiments operating in the HSI
color space, the corresponding average values can also be
determined for each pseudo-pixel of the PSEUDO IMAGE series, and,
for example, an average hue (or other statistical measure of hue)
can also be associated with each pseudo-pixel in the REFERENCE
IMAGE. Those skilled in the art will appreciate that other color
characteristics can be used alternatively or in conjunction with
the measure of RGB and/or hue. It will be appreciated that if only
one PSEUDO IMAGE is made per shade, then that PSEUDO IMAGE defaults
as the REFERENCE IMAGE since no other statistical combination is
available.
[0070] It should be noted that forming of pseudo-pixels is not a
requirement for practicing this invention. However, pseudo-pixels
are used in a preferred embodiment because they may reduce the
processing load of the system, minimize storage requirements and
also because they can simplify the task of aligning corresponding
pixels from different images. Proper pixel alignment is important
in order to ensure the integrity and accuracy of the statistical
averages used in the formation of REFERENCE IMAGES. In this regard
it will be appreciated that it is generally difficult to precisely
align all pixels in several images taken from the shades of the
same shade guide, unless there is extremely good control utilized
in the image capture sequence. Using pseudo-pixels in accordance
with the preferred embodiment reduces the total number of pixels
per image and thus simplifies the task of aligning different images
accurately.
[0071] Pseudo-pixels are even more important in later steps of the
processing method of this invention. That is, although one has
complete freedom to set up the optics and the camera, which
together determine the magnification of a captured tooth shade (or
tooth) image, when trying to "match" a REFERENCE IMAGE to an actual
digital image of a patient's tooth, the actual image (hereinafter
referred to as a SNAPSHOT) may be quite different in shape and size
(either real size or apparent size due to magnification differences
in the optics or camera CCD element size). As such, a "one-to-one"
comparison between the SNAPSHOT and the REFERENCE IMAGE is
difficult. Pseudo-pixels help in this respect because the SNAPSHOT
can be scaled to approximate the REFERENCE IMAGE size, or vice
versa; and the SNAPSHOT can also be processed into pseudo-pixels.
The scaled and pseudo-pixel version of the SNAPSHOT image is
denoted as the "REAL IMAGE" hereinafter. Pseudo-pixels used in a
preferred embodiment thus permit a convenient mechanism for
comparing a REFERENCE IMAGE to a REAL IMAGE.
[0072] In accordance with a preferred embodiment, the generation of
each REFERENCE IMAGE preferably includes a "bad pixel" routine
where each pseudo-pixel in the PSEUDO IMAGE series is analyzed for
bad pixels. A "bad pixel" means any real pixel corresponding to a
defective CCD element or corresponding to an area with an unwanted
artifact, e.g., reflection, in the digital image, or an area that
contains "background" imagery (e.g., any pixel image not
corresponding to the tooth or tooth shade). Any pseudo-pixel in the
PSEUDO IMAGE which contains a bad pixel is preferably not utilized
in the generation of the REFERENCE IMAGE. That is, if for example a
REFERENCE IMAGE is made up as an average of three PSEUDO IMAGES,
and yet one pseudo-pixel in one of the PSEUDO IMAGES contains a bad
pixel, then in a specific embodiment the resulting pseudo-pixel of
the REFERENCE IMAGE is either discarded, or computed only as an
average of the other two associated pseudo-pixels of the PSEUDO
IMAGES.
[0073] Note that the bad pixel routines are particularly important
at the edges of the image of the tooth or tooth shade. Consider,
for example, the shape of the tooth 40 in FIG. 3 or the irregular
shapes illustrated in FIG. 14. Clearly, such shapes are not
rectangular, and thus creating pseudo-pixels in accordance with the
preferred embodiment will result in certain pseudo-pixels having
bad pixels at the image edge. FIG. 4 illustrates bad pseudo-pixels
44a that contain pixels 42a, which are not part of the tooth image
40. Bad pixel routines used in accordance with a preferred
embodiment to detect such pixels and disqualify them from further
processing. For example, if 5% or more of the pixels within a
pseudo-pixel are "bad" (e.g., containing reflections or other
unwanted data), then such pseudo-pixels are disqualified. Though
not shown, other pseudo-pixels might be disqualified if for example
reflections from the light ports cause unwanted reflections in the
other pseudo-pixels image 40. In a preferred embodiment, such
pseudo-pixels are deleted from inclusion in the REFERENCE
IMAGE.
[0074] In a specific embodiment, the bad pixel routine need only be
implemented when capturing and generating REAL IMAGES. In that
process, conditions such as lighting and other variables can create
unwanted artifacts that should be eliminated from processing. In
addition, when cameras are used in the field, one pixel might
become defective over time; and REAL IMAGES later generated from
the defective camera should be adjusted so that the pseudo-pixel
which contains the bad pixel is not counted or utilized.
[0075] In another aspect, areas of the tooth for which the color is
to be evaluated are predefined, allowing the analyzer program
operating in accordance with this invention to batch-process the
images. For example, a sample image can be loaded into an Area
Selection Editor program module, where adjustments can be made to
user-selected (or predefined) areas of the tooth image. These
defined areas are then applied to each image in turn, and the pixel
colors within each area are analyzed. In operation, following the
image capture in one embodiment the method of this invention
proceeds to automatically select the area(s) of the sample for
analysis, for example, by applying a general rule to locate the
edges of the tooth in the image, and applying a predefined
segmentation of the remaining area for analysis. Preferably, the
user is allowed to manually select an area of interest in the
image, for example, using a computer mouse, as known in the
art.
[0076] In accordance with one embodiment, following the detection
of the correct areas for analysis (i.e., excluding edges, light
reflections and other unwanted artifacts), the selected area is
divided by using, for example, a grid overlay, as shown in FIG. 9.
As known, each shade has varying color content from top to bottom.
Therefore, in accordance with this embodiment a more accurate
analysis of the entire surface of interest can be made if color
determination and matching is applied to the individual cells of
the grid, as compared with corresponding area cells of the stored
color reference model for each shade guide.
[0077] Following this stage, in a preferred embodiment before
analyzing the area, various filtering operations can be applied to
the image, as known in the art. For example, filtering is applied
to eliminate abnormalities such as lamp reflections or dark spots.
In addition, maximum, minimum and average values for the R, G and B
components can be determined over the area of interest and used to,
for example, limit the variation from the average value to halfway
to the maximum and minimum values. This simple filtering operation
has shown satisfactory results in actual testing, although
alternative or additional filtering operations can be applied, as
known in the art in order to obtain a standard image.
[0078] In the next step of the method, a SNAPSHOT of a patient's
tooth is taken by the camera. Next, the digital image of the
SNAPSHOT is scaled, if necessary, to approximate the size of the
corresponding REFERENCE IMAGE. In the preferred embodiment SNAPSHOT
pixels are next processed into pseudo-pixels resulting in a REAL
IMAGE containing pseudo-pixels, which substantially correspond to
REFERENCE IMAGE pseudo-pixels. A bad pixel routine preferably
processes the REAL IMAGE to delete REAL IMAGE pseudo-pixels
containing a bad pixel. As above, the bad pixel routine is
particularly important at the edges of the tooth image within the
SNAPSHOT, where some pixels will certainly contain background
(unless the camera and optics are arranged to capture only the
tooth: however this is not efficient since effective matching
between the REAL IMAGE and the REFERENCE IMAGE occurs when a larger
area of the tooth is used in the comparison algorithms, which are
defined in further detail below).
[0079] In a subsequent step, the REAL IMAGE is compared (i.e.,
correlated) to each REFERENCE IMAGE in the database (e.g., there
could be sixteen REFERENCE IMAGES corresponding to the A1-A4,
B1-B4, C1-C4 and D2-D4 Vita Shades) via the correlation algorithm
(hereinafter "Correlation Algorithm") described below. In this
step, each pseudo-pixel of the REAL IMAGE is compared to each
pseudo-pixel of the REFERENCE IMAGE; and a composite match number
("CMN") is created indicating how well the REAL IMAGE matches to
that REFERENCE IMAGE. The composite match numbers are compared to
one another and one of the REFERENCE IMAGES is selected as the
"best fit" match to the REAL IMAGE.
[0080] There is potentially a problem associated with the bad pixel
routine and subsequent correlation between REAL IMAGES and the
series of REFERENCE IMAGES. As described above, in a specific
embodiment, when there is a bad pixel in any pseudo-pixel, all
other pseudo-pixels of the same spatial location are discarded.
This can become a problem in a case when every (or even most)
pseudo-pixel is disqualified, resulting in a situation where no
meaningful comparison can be made. Accordingly, in a preferred
embodiment, images are correlated on the basis of mathematical
measure, i.e., an average, that is functionally dependent upon how
many pseudo-pixels remain in an image (REAL or REFERENCE). That is,
for any given correlation between a REAL IMAGE and a REFERENCE
IMAGE, the number of pseudo-pixels for that comparison is used as a
ratio for comparison to other correlation. This aspect of the
invention is described in more detail below. In an alternative
embodiment, the averaging technique discussed above is used only
when, for example, more than 20-25% of the pseudo-pixels are
disqualified for all comparisons. Accordingly, so long as there is
a sufficient number of remaining pseudo-pixels for comparison, a
direct comparison of these pixels can be made without resorting to
averages. In a specific embodiment, a sufficient number is deemed
to be about 75-80% of the total number of pseudo-pixels available
for comparison. Other ratios can be used in alternate
embodiments.
[0081] Bad pixel routines are generally known in the art and thus
need not be described in much detail. It is sufficient to note that
in accordance with this invention a pixel is determined to be "bad"
if its light intensity or color values deviate by more than a
certain predefined percentage from adjacent pixels known to be
"good". For example, if a pixel deviates by more than 30% from the
light intensity of the neighboring 8 pixels, there is a good
likelihood that this deviation is anomalous, i.e. due to a bad
camera element or corresponding to an image border, and has to be
discarded.
[0082] In a preferred embodiment, a pseudo-pixel is validated only
when it contains less than a certain percentage, i.e., about 5%,
bad pixels of the total pixels making up the pseudo-pixel.
Preferably, bad pixels are also not used in the statistical
characterization (e.g., RGB) of the pseudo-pixel. Accordingly, in
this embodiment if more than about 5% bad pixels exist for a
pseudo-pixel, the pseudo-pixel is not used in further
processing.
Correlation Algorithms
[0083] In a preferred embodiment, the Correlation Algorithm of the
present invention operates as follows. Each REFERENCE IMAGE is
actually a matrix of vectors, each vector corresponding to a
pseudo-pixel. By way of example, the REFERENCE IMAGE corresponding
to the A1 Vita Shade can be assigned as vector Z.sub.A1. For the
sixteen Vita Shade guide, the remaining fifteen shades for example
each have a REFERENCE IMAGE too, e.g., Z.sub.A2, Z.sub.A3, etc.
[0084] Each REFERENCE IMAGE vector "Z"--corresponding to shade
guide or porcelain "X"--thus has data similar to the following
matrix:
Z x = PP x , 1 PP x , 2 PP x , 3 PP x , n = R x , 1 G x , 1 B x , 1
R x , 2 G x , 2 B x , 2 R x , 3 G x , 3 B x , 3 R x , n G x , n B x
, n ##EQU00001##
where each of the pseudo-pixels "PP" has three values for each of
R, G and B values of the pseudo-pixel (actually, the RGB values are
the statistically computed (e.g. averaged) composition of the
images in the series for that REFERENCE IMAGE, if available). The
subscript "x" refers to the appropriate shade, e.g., "A1".
Subscripts 1-n define separate pseudo-pixels in the REFERENCE
IMAGE. Those skilled in the art will appreciate that additional,
other or different data can make up each vector, including hue data
for each pseudo-pixel. Additionally, other vectors can be
considered and processed in the correlation, such as hue and RGB
values.
[0085] In a typical example, each REFERENCE IMAGE might have
20.times.20 pseudo-pixels which define the REFERENCE IMAGE.
Therefore, "n" in the above matrix is 400.
[0086] When a REAL IMAGE "I" is generated, in accordance with this
invention it too is arranged as a matrix of similar form, with each
pseudo-pixel "PI" of the REAL IMAGE being a vector of RGB form (or,
like above, containing other or additional factors such as
hue):
Z x = PI x , 1 PI x , 2 PI x , 3 PI x , n = R i , 1 G i , 1 B i , 1
R i , 2 G i , 2 B i , 2 R i , 3 G i , 3 B i , 3 R i , n G i , n B i
, n ##EQU00002##
[0087] In a specific embodiment, the Correlation Algorithm used in
accordance with the present invention computes a measure of
closeness, i.e., a composite match number ("CMN") through the
following relationship:
CMN x = q = 1 n ( Z x , q - I ) 2 = q = 1 n ( PP x , q - PI q ) 2
##EQU00003## CMN x = q = 1 n ( R x , q - R i , q ) 2 + ( G x , q -
G i , q ) 2 + ( B x , q - B i , q ) 2 ##EQU00003.2##
[0088] Once the CMN number is computed for each tooth shade, as
shown in the example above, a search is then conducted for the
lowest CMN.sub.x to find the best fit REFERENCE IMAGE for the REAL
IMAGE. That is, the tooth shade or porcelain "X" is identified for
the lowest associated value of CMN. As noted above, if there are
more than a certain percentage of bad pixels in any pseudo-pixel q
for either the REFERENCE IMAGE or the REAL IMAGE, in a preferred
embodiment that pseudo-pixel is not used in the valuation of CMN.
For example, in accordance with the present invention it is
acceptable to determine CMN without the q-th pseudo-pixel; however,
every other concurrent q-th pseudo-pixel valuation of CMN.sub.x in
identifying the composite match number is also discarded, so that
CMNs for all tooth shades can be compared correctly.
[0089] As noted, the Correlation Algorithm of the embodiment
illustrated above preferably uses a bad pixel routine to disqualify
bad pseudo-pixels. It was noted already that this can create
problems in certain situations. Accordingly, in a preferred
embodiment, the following alternative algorithm can instead be
used:
CMN x = q = 1 n ( R x , q - R i , q Pcount x ) 2 + ( G x , q - G i
, q Pcount x ) 2 + ( B x , q - B i , q Pcount x ) 2
##EQU00004##
[0090] In this embodiment for the computation of CMN Pcount,
corresponds to the number of common pseudo-pixels found between the
REAL IMAGE and the vector Z.sub.x. Note that Pcount.sub.x can be
different for each CMN correlation. For example, if the REAL IMAGE
has 400 pseudo-pixels, all good, and REFERENCE IMAGE for A1 has 399
pseudo-pixels (e.g., one bad pseudo-pixel identified in the bad
pixel routine), then Pcount.sub.A1 is 399. If however the REFERENCE
IMAGE for B4 has 256 pseudo-pixels, then Pcount.sub.B4 is 256. If
in the same example the REAL IMAGE has 256 valid pseudo-pixels--and
in the unlikely event that the disqualified REAL IMAGE
pseudo-pixels overlap with the coordinates of disqualified
pseudo-pixels in the REFERENCE IMAGE--then Pcount.sub.B4 is still
256; however Pcount.sub.A1 is also 256 (assuming that the one bad
pixel of REFERENCE IMAGE A1 corresponds to one of the disqualified
pseudo-pixels in the REAL IMAGE). If the one bad pseudo-pixel in
REFERENCE IMAGE A1 does not correspond to coordinates of one of the
disqualified pseudo-pixels of the REAL IMAGE, a more likely event,
then Pcount.sub.A1 is also 255.
[0091] Those skilled in the art will appreciate that isolating the
measure of closeness CMN in one of the above equations can also be
determined without the square root operation--as a minimum
composite match number will still be identified for the same
functional conditions and/or data.
[0092] In accordance with the specific embodiment described above,
the process of determining Pcount.sub.x can be made at any point.
In a preferred embodiment, this process is initiated only after a
certain percentage of pseudo-pixels are disqualified. For example,
if after the completion of the bad pixel routine there remain 300
pseudo-pixels for comparison (in the example that 400 pseudo-pixels
exist in each of the REFERENCE and REAL IMAGES), then a straight
comparison can be made without the use of the Pcount.sub.x
adjustment, because a significant percentage of the images can be
compared (defining 75% as "significant"; other percentages can be
used). Note that it is likely that many of the bad pixel areas in
images will overlap, such as at the edge of the image, where tooth
shape variations occur often, and at locations such as reflection
areas (e.g., areas which specularly reflect light energy to the
camera), which are likely to be similar given that the illumination
source is generally fixed for each image acquisition.
[0093] Those skilled in the art will appreciate that variations to
the above-described methodology may occur without departing from
the scope of the invention. For example, other color detection
techniques can be used to characterize tooth color within a
pseudo-pixel. In one example, colorimetric "laser-diode"
measurements can be used to generate a reflection trace for each
pseudo-pixel. In such measurements, a laser diode is "scanned" in
wavelength so that a laser beam, scanned through a range of
wavelengths, reflects off of each pseudo-pixel. This
spectrophotometric-like trace information (for example containing
reflectance per wavelength) can be collated with other such traces
for other pseudo-pixels to generate a vector of such information.
As above, correlation between real and reference vectors is used to
determine a best-fit color match.
[0094] In accordance with another embodiment of the present
invention, the camera used for capturing images has a focal plane
array with fewer detector elements as compared to typical high
resolution arrays (for example those arrays with 640.times.480
elements, or megapixel digital cameras). For example, in one
embodiment of the invention an array has a relatively small number
of detectors, i.e., 20.times.20, 60.times.40 or others. Such a
camera can alleviate the need for pseudo-pixels, as defined above,
since each real pixel generated from each detector covers a
relatively large area of the tooth image. In effect, such a camera
generates "pseudo-pixels" in each digital frame image. Since fewer
detector elements are used in this embodiment, it will be
appreciated that the camera's overall cost can be reduced. Those
skilled in the art will appreciate that a similar effect may be
obtained in an alternative embodiment by using magnification optics
that only utilizes a small portion of the camera's array in
obtaining the image; however such an approach wastes pixel
information which has already been collected.
[0095] Those skilled in the art will appreciate that other
closeness measures can be used instead of the algorithms described
above to achieve a similar result. By way of example, other
techniques of measuring similarity between two data sets can be
used in determining a measure of how similar or close two data sets
are. For example, one can arrange a data set as a vector so that
the correlation coefficient is determined as the cosine of the
angle between data vectors. Cross-correlation functions or matched
filtering can also be used beneficially. The interested reader is
directed to any number of books on digital image and signal
processing, such as, for example, Netravali and Haskell. "Digital
Pictures, Representation and Compression," Plenum Press, 1988.
Sections 1.1; 1.2; 1.3; 1.8; 1.9; 2.2; 3.2; and 3.3 of this book
are incorporated herewith by reference for background purposes.
[0096] In still another embodiment, the shape of the grid of
pseudo-pixels defining each tooth is selected in a manner dependent
upon how the tooth is positioned in the mouth. For example, an
incisor tooth very nearly maps to a shade guide; however, with
reference to FIG. 14, a posterior tooth does not, particularly
relative to the image capture position of the camera. Further, it
will be appreciated that for purposes of improving the appearance
of a smile, anterior teeth are considerably more important than
those in the posterior of the mouth. Thus, in a preferred
embodiment it is desirable to provide more close matches, and
correspondingly more dense and accurate grid patterns for the
anterior teeth. Accordingly, in a specific embodiment, grid shapes
and correlation algorithms can depend upon tooth orientation within
the mouth and/or upon generalized tooth shape. In particular,
anterior teeth will have a (proportionately) larger number of
pseudo-pixels than teeth in the back of the mouth for the same
surface area.
[0097] An image of a tooth or tooth shade may be analyzed by a
flood fill algorithm to find the edges of the target tooth or tooth
shade. Using this algorithm, from a point in the image (e.g., in
the SNAPSHOT) known to be in the tooth or tooth shade, adjacent
pixels are considered only if that pixel is in a valid color range.
The maximum extent is then recorded for the search in the X and Y
directions, forming the outer limits of the grid. In addition,
contrast changes in groups of pixels can be considered and used to
determine the extent; but a black border is easy to find.
[0098] In accordance with another important embodiment, "tooth
shades", as used above, are not used per se in defining a patient's
tooth color. Rather, in a specific embodiment, a grid of
pseudo-pixels is generated for the patient's tooth; and these
(pseudo-)pixels define the porcelain for respective regions of the
tooth. Pseudo-pixels are not actually required; and actual pixels
can also be used in this manner to define porcelain characteristics
for each spatial location in the mouth. Reconstructive tooth
material is then specified per pixel or pseudo-pixel. A data file
generated from the SNAPSHOT or REAL IMAGE is then processed to
specify reconstructive materials with spatial precision, as defined
by pixels or pseudo-pixels. An acceptable quantification of RGB
values, for example, can be used to tolerance both the measurement
and materials specification. For example, by associating error bars
with each measure--e.g., R+/-.DELTA.R, G+/-.DELTA.G, B+/-.DELTA.B,
where the .DELTA. quantities are defined within certain practical
tolerance limits--reasonable tolerances can be achieved. Tooth
shades operate similarly in that each shade results in a quantized
color difference from every other shade; and thus the
aforementioned tolerancing technique provides similar accuracy to
the above-described correlation algorithm. Unlike the tooth shade
approach, however, spatial accuracy for any given reconstructive
tooth is generally determined only by the number of pixels or
pseudo-pixels used in the reconstructive tooth manufacture; whereas
a tooth shade has predefined color gradients defining the tooth
shade regardless of the numbers of pixels or pseudo-pixels used. It
will be appreciated that this approach avoids the use of tooth
shades at all, along with the possible confusion created by the
existence of alternate tooth shade guides.
The Color Measuring System and its Components
[0099] Cameras of the type required for use with this invention are
generally known in the art and include, for example: INSIGHT.TM.,
manufactured in San Carlos, Calif.; CYGNASCOPE.TM. offered by
Cygnus Instruments, Inc., Goleta, Calif.; VISTACAM.TM. and others.
In a preferred embodiment, the system of this invention uses a
Welch-Allyn brand camera. Generally, it is desired to use camera
systems offering full-color imagery, which are capable of capturing
a range of sizes, i.e., from the size of a typical patient's tooth
preferably to images of the patient's whole smile.
[0100] In the preferred embodiment, it is advantageous for the
camera to supply a minimum 640.times.480 pixel image to the PC
software at 24 bits per pixel (i.e., 8 bits for each of the red,
green and blue (RGB) components), or preferably 30 bits per pixel.
In a specific example, the system of this invention uses ALARIS
QUICK VIDEO TRANSPORT frame grabber, providing digitized images
with at least 24 bits resolution. More specifically, the software
can use a Twain protocol interface, as known in the art, which
allows other cameras and frame grabbers to be tested without the
need for a change of software. Preferably, images captured by the
camera are displayed on a monitor screen to provide instantaneous
feedback to the system operator.
[0101] In another preferred embodiment, the resolution of the
camera is specified in terms of the Minimum Resolvable Color
Difference that the complete system is able to achieve. This can be
specified, for example, as the two RGB values of the two closest
shades the system is required to differentiate. For example, the
Chromoscop Shades 430 and 440 can be used to this end. In general,
it is envisioned that the system should be able to differentiate
between about 80 or more different shades. Another requirement is
that the system should be able to produce repeatable images. That
is to say that images of the same tooth taken at the same session
should not have a .DELTA.i of not more than 0.1, which is the
amount needed for the eye to perceive a difference. In a specific
embodiment, the camera used in the system of this invention is a
CMOS imager.
[0102] In terms of its physical setup, a stand-alone camera
containing its own light source can be used, as explained below. A
number of alternate embodiments are available in this regard. For
example, in one embodiment the camera can be battery powered. In
this embodiment, the camera sits on a holder containing an
inductive battery charger when it is not in use. In another
embodiment, when mounted on the charger the camera can be coupled
via an isolation sleeve (to be explained below) to a calibration
target, for example, made of porcelain.
[0103] In a specific embodiment the output of the camera is
supplied to a digitizer (such as a Sony digitizer) enabling
convenient digital storage of the image. As noted above, the output
of the camera can also be supplied to a frame grabber in a PC. Both
options can be used in a specific embodiment. In another
embodiment, the output of the camera can be supplied directly to a
monitor (preferably positioned close to a surgery chair) and
provide a digital output to a PC, which then need not be close to
the patient. As known in the art, the output could be USB-type, or
IEEE 1394.
[0104] In accordance with a preferred embodiment the digital output
of the camera also provides the opportunity to control the camera
from a PC. Finally, in a preferred embodiment it is desirable to
control the camera so as to use it in two modes, i.e., normal
image--for the mouth and full face shots; and analysis image--in
which color balance and automatic functions are disabled for tooth
and calibration image, as described below.
[0105] Turning now to the drawings, FIG. 1 shows a system 10
constructed according to a preferred embodiment of the invention. A
solid state (or intra-oral) camera 12 connects to a computer 14 via
a PC card 16 to capture images through a wand 18. The solid state
camera 12 includes a detector array 12a including an array of
detector elements 12b, which generate pixels in the digital images
(e.g., SNAPSHOTS) captured by the camera 12.
[0106] Through one of several known mechanisms, internal optics
within the wand 18 and/or camera 12 permit the capture of an image
of a target object 20 (for purposes of illustration, target object
20 is shown grossly over-sized as compared to other elements in
FIG. 1) by the array 12a. By way of example, relay optics 18a
within the wand relays an image to the array 12a. A protection
sleeve 22, discussed in further detail below (also grossly
oversized for purposes of illustration), preferably extends from
the wand 18. As shown, the optics provide an optical conjugate
between the array 12a and the target object 20 through well-known
imaging techniques. Light captured from the target object 20 enters
the wand 18 for transfer to the camera 12 through an entrance
aperture window 26.
[0107] The wand 18 generates light 19 to illuminate the target
object 20 through light ports 28. Preferably, light from the
outside 30 of a sleeve 22 is not permitted to illuminate the object
20 so that control is maintained; and thus the sleeve 22 shields
the target area 20 from illumination by outside sources 30 (e.g.,
ambient room lighting).
[0108] An aperture 32 within the center of the end piece 34 of the
sleeve 22 is where the tooth or tooth shade are placed so that a
SNAPSHOT (i.e., a digital image of the tooth or tooth shade) can be
made. As discussed above, these SNAPSHOTS are processed to form
REAL IMAGES (from real teeth) or REFERENCE IMAGES (from tooth
shades or porcelains, etc.).
[0109] A black border 36 around the aperture 23 provides a good
reference around which the tooth or tooth shade are discernible
within the digital image of the target area 20. The remaining area
38 about the border 36 and within the end piece 34 is preferably a
white reference sample, equally reflecting all light 19 from the
light ports 28.
[0110] Finally, again with reference to FIG. 1, digital images from
the camera 12 are sent to the computer 14; and processing software
50 within the computer 14 processes these images to generate a CMN
for each REAL IMAGE relative to the REFERENCE IMAGES. As discussed
above, the software 50 processes the CMNs to locate the lowest
value CMN, indicating a match; and communicates the associated
shade of that lowest CMN to the user via signal line 52. As
mentioned, other processing algorithms can be developed to
determine a best-fit match without departing from the scope of the
invention.
[0111] A representative digital image 31 captured by the camera 12
is illustrated in FIG. 2, showing an image 36' of the border 36, an
image 38' of the reference sample 38, and a tooth image 40. The
entire image 31 covers the target area 20 of FIG. 1. FIG. 2 also
illustrates obvious regions 41 of the image 31 that would generate
bad pixels since such regions do not contain tooth imagery but
rather other background imagery (e.g. the patient's gum).
[0112] FIG. 3 shows a blow up image of the pixels 42 (only
representative pixels 42 are shown), which make up the tooth image
40 of FIG. 2. In accord with the invention, these pixels are
transformed into pseudo-pixels 44 of FIG. 4. Each pseudo-pixel 44
is made up of all or some of the real pixels within the area of the
associated pseudo-pixel 44. Two pseudo-pixels 44b illustrate, for
example, how a pseudo-pixel can be generated from nine real pixels
42. FIG. 4 also illustrates that an image can be made from either a
real tooth 40 (resulting in a REAL IMAGE) or a reference shade 40
(resulting in a REFERENCE IMAGE). REAL IMAGES and REFERENCE IMAGES
are correlated to find the composite match number (CMN) as
described above.
[0113] FIG. 5 shows another embodiment of an end piece 98 used in
accordance with a specific embodiment, that mounts to or is made
integrally with, the end of the sleeve (e.g., the sleeve 22, FIG.
1) and which has a series of tooth shades 100 disposed in the end
piece 98, so that for each target 102 (e.g., the tooth or tooth
shade), all relevant manufacturing shades are provided in the same
digital image, thereby preventing color contamination or other
anomalies caused by time delay. As discussed above, when using the
end piece 98 of this embodiment each shade 100 is processed as a
REFERENCE IMAGE and the tooth 102 is processed as a REAL IMAGE
relative to those REFERENCE IMAGES to find a CMN. Preferably, a
black border 104 surrounds the tooth aperture 106 and tooth 102.
Also preferably, the remaining area 116 about the border 104 and in
the end piece 98 is a reference area. By way of example, the
reference area 116 is a white reflecting region which can be
sampled by detectors that image that region 116. Further examples
of the use of reference area are discussed below.
Isolation Sleeve
[0114] In a preferred embodiment, an isolation sleeve is used to
reduce variations in the images captured and processed by the
system, and in particular to eliminate light contamination from
external sources. In addition, the isolation sleeve preferably
keeps the reference shade and the actual tooth at a set distance
from the illumination source and the camera optics. The sleeve also
preferably sets the angle of illumination between the source and
the tooth so as to reduce reflections. More particularly, the
REFERENCE IMAGES and the REAL IMAGE are preferably taken at the
same illumination intensities, at approximately the same distance,
and without substantial specular reflections from the source. To
this end, in a preferred embodiment the sleeve shields the camera
detector from imaging outside light and instead utilizes internally
generated light (i.e., internal to the camera, for example, or
associated with an intra-oral wand attached to the camera) that can
be controlled. The sides (or side) of the sleeve are coated in a
specific embodiment with a black material (e.g., a paint or a black
mat paper, or black felt), which reduces reflections along the
sleeve to the tooth or reference shade. As used herein, "target
area" refers to the image gathering location that the system of the
invention (i.e., that region captured by the camera's detectors),
including the REAL or REFERENCE IMAGE, as defined above.
[0115] FIG. 6 shows one end of wand 130 and a sleeve 132
constructed according to a specific embodiment of the invention. As
in the example shown in FIG. 1 above, the wand 103 connects to a
solid state camera (not shown, for purposes of illustration) to
collect digital images of the target region 134 at the end of the
sleeve 132. By way of example, the target region 134 includes an
aperture (not shown) for imaging a tooth therein. Light 135 from
the camera or wand 130 exits the wand 130 at optical aperture 136
to illuminate the target region 134.
[0116] In a specific embodiment illustrated in FIG. 6, the sleeve
132 used in the camera system of the present invention includes an
accordion-like exterior, which permits soft placement of the end of
the sleeve onto the patient's tooth. Preferably, such a sleeve is
not entirely rigid so that the sleeve 132 can make contact without
concerns about damaging the tooth. The outer portion of the sleeve
132 in this embodiment thus acts similar to a spring, and an inner
structural member within the sleeve sets the final source-to-tooth
distance once the outer sleeve/spring compresses to the desired
location.
[0117] As shown in FIG. 6, the accordion-like sleeve 132 compresses
between the target region 134 and the wand 130, as shown by
compression arrow 138. In operation, a user of the wand/sleeve
130/132 pushes the sleeve 132 to the patient's tooth, and the
sleeve 132 compresses to provide comfortable (i.e., non-rigid)
contact with the tooth. In a preferred embodiment, the sleeve 132
is spring-like to provide some force opposing compression. This
force increases until there is an interaction between the sleeve
132, and/or the end piece of the sleeve 132 (i.e., the part of the
sleeve at the target region 134), and the rigid structural member
140 within the sleeve 132. The member 140 stops compression at a
fixed location so that a set distance is achieved from the aperture
136 and the target region 140; and so that a repeatable image size
is attained.
Illumination
[0118] As noted, in a preferred embodiment, the camera system of
this invention includes a light source that illuminates the target
area. In a specific embodiment the sleeve 132 can be made to rotate
so that images are gathered from difficult locations in the mouth.
Preferably, the light source is tied to fiber optics which rotate
with the sleeve so that regardless of sleeve position the
source-to-target area remains approximately fixed. In another
aspect, the camera includes optics, such as image collection optics
and/or an entrance window. In an embodiment including this feature,
the camera optics is tied to fiber optics, so that images are
captured effectively regardless of the position of the sleeve.
[0119] In another aspect, the sleeve used with the dental camera
system of the present invention incorporates imaging optics which
relay the tooth image through a Lyot stop, to prevent passage of
unwanted light energy to the camera detectors. In a specific
embodiment, the sleeve incorporates baffling--such as "two-bounce"
optical stray light baffling--to reduce or substantially eliminate
stray light from external sources to the desired tooth image
area.
[0120] FIG. 7 shows illumination arrangement wherein the source 150
of the illuminating wand 152 (connected to the solid state camera,
not shown) is angled from the target area 154. As shown, the sleeve
156 connected to the wand 152 is arranged adjacent to a patient's
tooth 158, so that digital images can be taken of the tooth 158
(according to the practices discussed herein) through the wand's
optical entrance aperture 160.
[0121] For purposes of illustration, FIG. 7 also shows how light
162 emitting from the source 150 travels in a generally specular
direction 164, reflecting off the tooth 158 into a direction 166
that is away from the aperture 160. Those skilled in the art will
appreciate that scattering does occur off the tooth 158 and into
the aperture 160, but that the arrangement eliminates some unwanted
reflections into the aperture. Light captured through the aperture
160 is relayed by optics (e.g., fibers and/or relay lenses) to the
camera's focal plane (not shown) to generate digital images of the
tooth 158.
[0122] FIG. 8 shows another embodiment of a sleeve 168 constructed
according to the invention to reduce passage of light 171 into the
wand's entrance aperture 169 from sources 170 away from the target
object (e.g., the tooth 172). The sleeve 168 is especially useful
in imaging the tooth 172 without adjacent proximity to the sleeve
168, as illustrated in FIG. 8. The sleeve 168 includes baffles 168a
known in the art, which require at least one "bounce" and
preferably two bounces of the light 171 prior to gaining access to
the entrance aperture 169, thereby significantly attenuating "out
of field" sources 170 (i.e. those unwanted sources which might
influence the color measure, e.g., room lighting). For simplicity,
in this illustration the wand and solid state camera are not shown.
Baffles 168a can be placed within other sleeves shown herein to
improve out-of-field stray light rejection.
[0123] As noted above, in order to ensure high-quality images which
do not depend on the specific lightning conditions at the time the
pictures are taken, in accordance with this invention it is
important to minimize the influence of such factors. Accordingly,
in another specific embodiment, the sleeve used in the dental
camera system of this invention includes a reference sample
disposed at the end of the sleeve, near the target area, so that:
(a) color comparison information can be obtained; and/or (b) the
camera has sufficient reflective surfaces from which to effectively
trigger the camera's auto-brightness and/or auto-color features.
Specifically, as to feature (b), certain cameras available on the
market include electronics and software which automatically adjust
brightness and/or color in a digital image. Preferably, in this
embodiment such features are disabled. In the event they are
operating, however, the reference sample is sized so that a
sufficient reflection area is generated at the end of the sleeve,
whereby the camera can operate to capture good color images. By way
of example, as to feature (b) above, the sample should be sized so
that RGB values vary in a controlled or calibrated manner
throughout the reasonable tooth shade reflections (e.g., throughout
all VITA Shades).
[0124] As to feature (a) above, one preferred embodiment utilizes
the reference sample to obtain a color reference used to reduce
variations in the digital image. "Color" is based on
"reflection"--that is, what the camera sees at the target area is
based on reflection of whatever source illuminates the target. With
the sleeve used in a preferred embodiment, the source is limited to
the camera's illuminating source, thereby eliminating other sources
and color variations that are not controllable (e.g. the ambient
lighting in a building). It is well known that a black body absorbs
visible light; and a white object reflects the light. In one
embodiment, therefore, the reference sample is as white as possible
so that it exhibits very little color (and particularly, the sample
reflects light equally in the visible light range from between
about 400 nm to 800 nm). When using a white reference sample in
accordance with this embodiment of the invention, the following
process occurs:
[0125] 1) Compute average RGB values (and/or other image variables
such as hue) for several or all pixels imaged of the reference
sample. This computed average is referred to as REF RGB. [0126] 2)
For each digital image (i.e., for both REFERENCE IMAGES and REAL
IMAGES), subtract REF RGB from RGB pixel values for that image.
Keep track of the sign (i.e., positive or negative) of the result.
The result is referred to as "REF RELATIVE RGB" (i.e. image RGB-REF
RGB). [0127] 3) Utilize a correlation algorithm, such as described
above, (i.e., for the CMN) on REF RELATIVE RGBs as opposed to
absolute RGB values (for the pseudo-pixels). Note that when the RSS
(i.e. subtract and square) of the CMN algorithm is computed, the
sign of the REF RELATIVE RGB matters. For example, if the REFERENCE
IMAGE RGB is -0.1, -0.5, -0.6, and the REAL IMAGE RGB is
0.1,0.7,0.9, then this REAL IMAGE has quite a bit more color
difference (compared to the REF IMAGE, which is the important
quantity) than, e.g., a REAL IMAGE with -0.05, 0.2, 0.1.
Afterwards, the square of the RSS destroys the sign importance.
[0128] The reference sample compensation algorithm described above
is used in a specific embodiment to compensate for certain
variations. Thus, the auto-brightness feature of certain cameras
changes the color of the light emitted from the camera (this is
sometimes referred to in the art as the color temperature).
Unfortunately, the emitted RGB is not known except for the
reference sample, which reflects the source light back to the
camera detectors. A good reference sample will thus reflect nearly
all colors equally. Since one is interested in differences between
REAL IMAGES and REFERENCE IMAGES, the real concern involves
differences and not absolute colors.
[0129] The reference sample compensation thus also compensates for
image acquisition changes which occur over time. For example, the
source may emit more or less light, over time, even over several
minutes or hours; and it would be desirable to eliminate such
variations to increase the sensitivity to color comparisons. The
passage of time during an image acquisition sequence only adds to
the variability in the measurement: the source color temperature
may change, the detector sensitivity or gain may change, etc. With
the above reference sample adjustment, if for example one has a
perfect white tooth, then its REF RELATIVE RGB is 0,0,0. Assuming
that a tooth shade exists that was also perfectly white, it would
have a REF RELATIVE RGB of 0,0,0--creating a match.
[0130] In another embodiment, the white reference is integrated to
find REF RGB, per frame. REF RGB is then subtracted from each pixel
RGB in the image (or the other way, i.e., image RGB subtracted from
REF RGB, as long as consistent throughout every measurement). In
another embodiment, REF RGB is subtracted from pseudo-pixels; but
preferably REF RGB is subtracted from real pixel RGBs.
[0131] In another embodiment, the sleeve used with the dental
camera system of the present invention is formed in the following
way. At the end of the sleeve, a central aperture exists preferably
in the middle of the target area (e.g., an object such as a tooth
or shade is placed at the aperture). Surrounding the central
aperture is a black border, to provide high contrast at the edges
of the target object. A target object such as a tooth is thus
readily defined and discerned within the black border. The aperture
also fixes the size of the image for the tooth or tooth shade. Some
or all of the remaining area at the end of the sleeve (captured by
the camera detectors) in the target area is a white reference
sample.
[0132] The amount of white reference sample in the target area can
be chosen experimentally. By way of example, the average mid point
in the auto-brightness (if operating) is obtained so that on
average REF RGB changes little. The size of the white sample in the
target area is adjusted in area until REF RGB is minimized for all
shade values, e.g., A1-A4. B1-B4 and so on. With more black in the
image due to less reference sample area, the auto brightness
control on the camera (if applicable) adjusts to higher gain to
`balance` the intensity of the image, causing the reference and
sample parts to saturate in the red and green.
[0133] As noted above, in a specific embodiment, the walls of the
sleeve are selected mat black to eliminate reflections, but the
facing plate containing the target area is bright to force the
camera gain downwards, out of non-linear color operability. In this
embodiment preferably the camera's auto features are turned off
(and at least any white balance is set to manual). In one specific
embodiment, the reference sample is made of a light colored felt
material. In alternative embodiments, the sleeve walls are made of
a felt material. In these embodiments, the felt material has
elements which extend away from the material producing more of a
lambertian surface. Such surfaces are preferred as they reduce
unwanted specular reflections. Also, the sample reference produces
an excellent image when it is not specular. Alternatively, a black
velour paper can be used in the sleeve, such as by J L Hammett
Co.
[0134] FIG. 10 illustrates a non-contact re-imaging system 250 used
in accordance with another embodiment of the present invention to
image a target tooth 252 without contact between the tooth 252 and
a sleeve 254. Optics 255 reimage the tooth 252 internal to the
sleeve 254, at internal image 256, and a Lyot stop 258 is used to
reduce unwanted stray light entering the aperture 260 to the camera
(not shown).
[0135] FIG. 11 illustrates a non-contact re-imaging system 300 used
to image a target tooth 302 to a digital camera 304, and without
contact between the tooth 302 and the system 300 or camera 304.
Although this reimaging system 300 can be made in several forms, in
one embodiment the system 300 includes a sleeve 306 that permits
hand-held manipulation into a patient's mouth to capture the
digital image of the tooth 302. By way of example, optics 308
reimage the tooth 302 internal to the sleeve 306, at internal image
310, and a stop 312 is used for color referencing in analyzing the
tooth color. Stop 312 forms an aperture defined by edge 312a. FIG.
12 illustrates one digital image 320, as taken by camera 304, of
the tooth 302 and the inside view of stop 312. The region 322
defines that region inside the patient's mouth that is not the
patient's tooth 310. Region 324 consists of a color reference which
is used as described herein to relate and compare to color pixels
of the digital image of the tooth image 310, so as to better define
tooth color. Region 324 is preferably the inside of stop 312.
[0136] Those skilled in the art will appreciate that a reimaging
system such as in FIG. 11 can be made in several ways. By way of
example, system 350 of FIG. 13 shows one system of the invention to
reimage a tooth 352 to an internal image 354 for reimaging into a
digital camera 356. As above, camera 356 takes SNAPSHOTs of the
tooth 352, for color analysis. Optical element 358 images the tooth
into optical fiber bundle 360, which relays the image from one side
360a to the other side 360b of the bundle 360, as known in the art.
Optical elements 362-provide for reimaging to form the internal
image 354 at the stop 364. As above, the stop 364 has a reference
color disposed thereon, facing camera 356, so that a reference
color image is attained such as in FIG. 12. Fiber optic bundle 366
relays the image 354 from side 366a to 366b, and exit optics 368
provides for relaying the tooth image to the camera 356. One
convenient feature of system 350 is that fibers 366, 360 can be
flexible; and a sleeve 370 can support these elements to provide a
hand-held wand that can be inserted into a patient's mouth to
acquire the image. Camera 356 can provide its own light source 356a
which generates light 356b back along the optical path taken by
tooth image 354. The advantage of this is that source 356a can be
carefully selected for its color characteristics to facilitate
tooth color detection; and further light 356b can illuminate stop
364 inside the sleeve or wand 370 so that the camera 356 can detect
and compare its color to the tooth's color image 354.
Tooth Restorative Processing
[0137] FIG. 14 shows certain tooth restorations and decays, which
illustrations can help understand more fully aspects of the
invention discussed above. A healthy tooth, free from any decay
with no current restoration ("restoration" is any part of a tooth
that is replaced with a material that allows the tooth to remain in
the mouth as a functioning and whole structure) is referred to as a
"virgin" tooth. Despite advances in preventative treatment and
services (fluoridated water, fluoride treatments, sealants--which
are unfilled resins that are bonded into deep grooves of posterior
or back teeth to prevent decay in those areas), 50% of American
children by age 12 have occlusal decay (decay in the top, or biting
surface) in permanent molars which erupted or came into their
mouths at age 6.
[0138] Typical progression of decay in a tooth is as follows:
Following C. V. Black's classifications, a tooth can require a
restoration in the following positions:
[0139] CLASS 1--occlusal area, that is, within only the top or
biting surface of the tooth, usually beginning in the groove or
crevice. This term is used only for posterior (back) teeth, i.e.
molars and premolars.
[0140] CLASS 2--area made up of occlusal and one or more sides of
the tooth, either mesial (wall towards front) and/or distal (wall
towards back) and or buccal (wall towards cheek) and or lingual
(wall towards tongue) so that a class 2 restoration may be termed
"MO" (mesial-occlusal), "MOD", "OB", etc.
[0141] CLASS 3--area of an anterior, or front, tooth involving only
an interproximal wall, that is mesial or distal, areas that face
neighboring teeth.
[0142] CLASS 4--area of an anterior tooth involving the incisal
(bottom) edge and an interproximal wall.
[0143] CLASS 5--area of any tooth on only the buccal or lingual
wall.
[0144] CLASS 6--area of a tooth involving the cusp tip (cusp being
the highest point of the tooth, like the mountain peak; this would
apply to canines, premolars, and molars).
[0145] Once decay is detected, through clinical examination,
radiographs, etc., the decayed portion of the tooth needs to be
removed. This is achieved through the use of a handpiece (drill).
Once excavation of decay is complete, the remaining tooth structure
is evaluated for restoration possibilities. A "filling" is placed
if 50% or more of the tooth remains, with the stress-bearing areas
of the tooth remaining intact (such as cusps and walls of the tooth
which are active in biting and chewing process). If these areas of
the tooth are compromised, a laboratory-processed restoration is
required.
[0146] Consider a specific example, in which it is assumed that the
tooth needs a restoration, which will be placed right in the
office, say a MO on a molar. The choice of materials is made, which
could be either amalgam (silver, not done much any more), or
composite or ceromer, which are tooth-colored direct materials
(Matrix of ground plastic and/or glass in a bis-GMA resin). A shade
needs to be selected for the material, such as described herein in
accord with the invention. The tooth is cleaned and isolated from
saliva and blood by use of cotton rolls, matrix bands, possibly a
rubber dam. The tooth surface is etched with a cleanser (typically
37% hydrophosphuric acid), rinsed, and treated with an adhesive,
which is bonded to the tooth by use of a curing light--a light with
a wand attachment that is about 11-13 cm in width and emits a light
in the range of 400-500 nanometers. The material is then placed
into the cavity by hand instruments or via dispensing through a
carpule/cartridge system in a syringe. The material is somewhat
condensed into place at 2-3 mm intervals, and light cured in
between. Upon final filling, the restoration is polished and
contoured using finishing burs (tips) on the handpiece (drill).
[0147] If the tooth requires a lab fabricated restoration, such as
an inlay, onlay or crown, further steps need to be taken (Inlay
being a Class 2 restoration NOT including cusps, onlay being a
Class 2 restoration including cusps, crown being full, or total
coverage of the tooth). The tooth is shaped to make the final shape
not have any undercuts, with walls as parallel as possible for
retention purposes.
[0148] Then an impression, or mold is taken of the tooth, which is
in a material that remains accurate despite temperature changes,
moisture, pouring stone into the mold and removing it several
times. An impression of the opposite arch of teeth, or opposing
arch, is taken also so that the technician can articulate, or put
together the two arches and simulate the patient's mouth or bite. A
registration of such a bite can be taken also and sent with the
case. So that the things sent to the lab for such a case are:
impression of the tooth to be restored and adjacent teeth, model or
impression of opposing teeth, and possibly a bite registration.
[0149] Those skilled in the art should appreciate that the
invention to determine the appropriate color shades of the tooth as
illustrated in FIG. 14 can be accomplished by the methods herein,
and/or by systems disclosed in the several figures. Using a wand of
the invention, furthermore, various teeth (as in FIG. 14) can be
acquired for digital evaluation. In accord with the invention,
digital files of patients' teeth can be stored in memory of
computer 14, FIG. 1, for a permanent record. A patient can then be
evaluated over time for color changes.
Multifaceted Tooth Restorative Processing
[0150] In dental restorative cases, the general dentist is the
master planner, or gatekeeper of all phases of the patient's
treatment. In some more complex cases, the general dentist still
performs this function even if the dentist does not perform the
dental restoration. For example, consider an adult patient that is
suffering from malocclusion or misalignment of teeth. Nearly
everyone has some degree of malocclusion, although it is not
usually serious enough to require treatment, however, some patients
may require multidisciplinary treatment. Most instances of
malocclusion are discovered by general dentists during a routine
examination. The general dentist usually refers the patient to an
orthodontist for further diagnosis and treatment. In some instances
extraction of one or more teeth may be required if overcrowding is
part of the problem. This is usually performed by an oral surgeon
but may be performed by a general dentist as well. In some
instances an oral surgeon may place implants to serve as locator
attachments for removable partial dentures that are designed by the
general dentist, a prosthodontic lab practitioner or technical
sales rep. The general dentist may also adjust, reshape, bond, or
cap any remaining rough or irregular teeth. Thus, the treatment
plan from start to finish can involve a general dentist, an
orthodontist, an oral surgeon, a removable prosthodontic lab
technician, a technical sales rep, the patient, or a combination
thereof. This type of treatment plan can require considerable
amount of information exchange between the practitioners involved,
and consequently can be time consuming, inefficient, and
troublesome. As further discussed below, a computer-based dental
restoration system can provide a more smooth implementation of the
treatment plan if some or all the practitioners involved use the
system to examine a video, an X-ray, or images of the patient's
mouth together simultaneously, or substantially simultaneously, in
disparate locations. The system can provide further advantages if
some or all the practitioners use the system to directly
communicate with each other in addition to using the system to
examine images of the patient's mouth.
[0151] The provision of a dental restorative network for
communication between a lab and dentist also facilitates
participation by other users in an expanded network, which would
allow multiple users to simultaneously access the same case and
have a "conference" in real time to discuss treatment
possibilities, troubleshoot the case, and have interdisciplinary
discussion of phases of treatment for a patient.
[0152] In a preferred embodiment, the computer-based dental
restoration system includes a network server having a database for
storing digital representations, and a communications network
providing access to the network server and facilitating direct
communication at least between a dentist and a practitioner. The
system further includes one or more computers for accessing digital
representations over the communication network. The one or more
computers can display the digital representations in a convenient
format. Preferably, the practitioner includes one or more of a
dentist, a dental specialist, a dental restoration manufacturer, an
authorized user, or a combination thereof. Illustratively, the
dentist and or a practitioner can set up a Web site for a patient
by storing the patient's digital representations onto the database
of the server. The storing of patient's digital representations is
preferably performed using a loading application for loading the
digital representation into the database.
[0153] Advantageously, the digital representations include one or
more of a patient's dental record or aspects thereof, an x-ray of a
patient's tooth, a digital image of a patient's tooth, a video
image of a patient's tooth, or a preliminary dental treatment plan.
The digital representations preferably further includes a digital
impression which is a three dimensional model of the treatment
area. Preferably, an intraoral scanner is used to form this three
dimensional geometry. In some embodiments a dental cast can be used
to obtain a digital impression. The digital impression can provide
detailed model of the treatment area. A Computer Aided Design (CAD)
machine can use the detailed model to design, for example, a fixed
prosthodontics. This design can subsequently be applied by a
Computer Aided Mill (CAM) machine in the fabrication of the fixed
prosthodontics. In another application, the digital model can be
used in a simulation of a patient's course of treatment, where the
dentist, practitioners, and possibly the patient can observe
various stages of the treatment on a computer monitor. The
simulation can be visually displayed for example, by a computer
monitor, a television, a holographic display, or other devices
known in the art. The simulation can be displayed on devices
capable of displaying 3-D images or stereo images, from a plurality
of view points, and plurality of projection types. Preferably, the
dentist and practitioners can attach text, voice, video, and files
to a particular digital representations or portions thereof. In yet
another application, multiple forms of digital representation can
be compiled into a multi-layer object for visualization and
analysis of a treatment area. For example, an X-ray of a treatment
area can be projected on to a cross-section of a digital impression
of the same area.
[0154] The Web site can control access using a user name, an
identification number, a password, and possibly other means to
protect patient's privacy and to comply with Health Insurance
Portability and Accountability Act (HIPPA). As further discussed
below, the Web site also can include a number of individual
demarcated sections or Web pages that allow or deny access as
needed (see FIG. 18). For example, the dentist might be allowed
access to all information for all patients, whereas the another
practitioner or a guest practitioner might be permitted access to a
certain portion of a patient's record while providing consultation
to the dentist. Once the Web site is properly configured, the
dentist for example, may invite other practitioners to join him/her
in a conference to discuss a patient's treatment plan. The dentist
and practitioners (i.e., participants) preferably access the
database via a client application running in one or more computers.
Preferably, the client application includes a Web browser that can
connect to the Web server for access to the database. The
participants can also conference together, preferably via
establishment of direct communication, using for example a HIPPA
compliant client-server instant messaging application, such as,
Mirador instant Messenger or other instant text and voice messaging
tools known in the art. The participants develop an initial
treatment plan, or meet later in the treatment to access progress,
or to troubleshoot problems that may occur. Preferably, the one or
more computers provides the participants simultaneous access to at
least one of the digital representations.
[0155] FIG. 19 illustrates in a block-diagram form the operational
process of the computer-based interactive network system in a
preferred embodiment. In operation, the dentist stores a patient's
record 1910 on the database using a loading application 1905. The
patient's records can include, for example, an X-ray, images, a
digital impression, and a treatment plan. The loading application
1905 may allow the dentist to send e-mails 1935, containing the
HTTP link to the site storing the patient's record, inviting other
practitioners to join in. In some instances, the dentist might
extend a conference invitation to other practitioners using an
instant messaging application 1940. Upon connection to the server
1950, the participants can be promoted to login 1955 using a user
name and a password previously assigned 1920 by the dentist, the
server can then authenticate 1965 the user and provide access to
the patient's record according to privileges previously set 1925 by
the dentist. In certain instances, the client application running
on the participant's computers can download a plug-in before
launching an application 1970. The participants can then
interactively access, operate or manipulate the data stored on the
database 1980. Preferably, the participants can have simultaneous
access to the database while directly communicating with each
other, for example, using an instant messenger application
1940.
[0156] In another embodiment, the computer-based dental restoration
system can communicate information between the dentist and
practitioners via e-mail. In this case, at least one of the one or
more computers, the server, or both include an application that
provides access to the database via e-mail. For example, the
dentist can request the application to send e-mails, via the
communication network, containing a set of digital representations
of a patient to one or more practitioners. The practitioners can
then be notified by the application upon reception of the e-mail
from the dentist.
[0157] As another illustration of the present invention consider
the fabrication of fix prosthodontics. Traditionally, if a patient
needs fixed prosthodontics, such as a crown, the dentist would be
required to obtain a full or partial cast from the patient's mouth
(teeth) and send the cast along with the preparation instructions
to a laboratory practitioner for design and construction. Often,
this process would be followed by further communication between the
doctor and the laboratory practitioner to resolve any questions
that the laboratory practitioner may have, or the laboratory
practitioner informing the doctor that additional modification or
steps would be required by him/her to ensure proper fitting. For
example, in some cases the dentist may be required to take a new
impression due to ineffectiveness of the original impression or
perform further tooth reduction to allow for clearance, which would
mean more chair time. Generally, the entire process for a crown may
take several weeks depending on the complexity of the case.
[0158] Advantageously, digital representations allow for
communication of detailed information regarding patients to various
practitioners for consultation and development of treatment plan. A
digital impression from a patient's mouth or teeth can provide the
necessary information for a practitioner in a dental laboratory to
build a prosthesis for the patient based on the instructions from a
dentist. In accordance with the present invention, a dentist can,
for example, use an intraoral scanner to obtain a digital
impression of the mouth or part of the mouth requiring treatment.
The dentist reviews the digital impression on the chairside screen
at the same time a validation program can be run to determine the
effectiveness of the impression. If the dentist has a CAD/CAM
machine in the office, then the dentist can choose to design the
crown himself/herself, alternatively, the dentist can choose to
utilize the talent of a prosthodontic lab practitioner for this
work.
[0159] If the decision is to let the prosthodontic lab practitioner
do the design, then the digital impression data can be sent,
preferably by Internet, to the design lab, with the patient still
in the chair. The prosthodontic lab practitioner receives the data
and designs the case by operating on the data received from the
dentist, and sends the designed crown back to the dentist for
his/her review and acceptance. Generally, the time required for
data exchange and design of the crown can be of order of minutes,
for example 10 minutes, and can cost the dentist less $100, for
example $45 in the 2006 valuation. The dentist upon receiving the
designed crown can review it, and accepts it or reject it, with the
patient in the chair. If acceptable, the dentist can choose the
design lab to mill the crown with possibly additional directives,
for example, more translucency must be added to the crown to match
the other teeth. The dentist can choose to mill chairside if the
crown as designed can match using the chairside blocks without
other characterization. In the former case, the dentist can deliver
the crown to the patient in just a few days; in the latter case, a
single office visit can afford the patient a new crown.
[0160] In another preferred embodiment, the computer-based dental
restoration system includes a network server having a database for
storing information about materials, procedures, preparations
concerning dental restoration prostheses, and digital
representations. The system further includes a communication
network providing real-time access to the network server, and at
least a dentist and a practitioner. The computer-based dental
restoration system also comprises one or more computers for
accessing the database over the communications network and
displaying the information in a humanly readable format.
Preferably, the communications network is configured to enable the
dentist to communicate a prostheses specification, consult with the
practitioner, obtain cost and viability options for presentation to
a patient, and place an order with the practitioner, wherein
elapsed time for the whole process is less than four hours. More
preferably, the elapsed time is less than one hour.
Miscellaneous Aspects
[0161] Although the VITA.TM. Shade guide is often discussed herein,
it should be apparent that other shade guides and porcelains can be
stored as REFERENCE IMAGES and compared to REAL IMAGES in
alternative embodiments of this invention. Computer memory can
store a large number of images, even from different manufacturers,
so as to provide the optimum color fit to a patient's tooth. By way
of example, IVOCLAR has one suitable shade guide, as well as
various materials of porcelains, ceromers, polymers, and others. In
accord with the invention, a database can store REFERENCE IMAGES
for match correlation to REAL IMAGES. Alternatively, in one aspect,
the invention performs a conversion to other manufacturer shades
and or porcelains so that alternative laboratories can be used
without undue concern for manufacturer alliance. Specifically, in
accord with one aspect of the invention, a conversion between known
shade guides is provided for increased lab selectivity. It will be
appreciated that the conversion of digital images involves mapping
from one set of color coordinates to another, which procedure is
well known in the art and need not be considered in further
detail.
[0162] As described, one major problem due to auto brightness is
that if there is not enough light material in the image, the auto
brightness turns the gain up too high, and the R and G values
saturate in the sample. By adding sufficient light colored
reference area, the balance of light to dark is better, but the
reference can saturate in places. This can be compensated some by
using an end plate at the end of the sleeve that will be all white
but with the black border round the sample aperture. A reference
color area can be included in one corner so that the camera adjusts
brightness for the constant white area leaving the reference and
sample somewhere in the middle of the operable RGB ranges.
[0163] In still another aspect, instead of subtracting the RGB from
the reference sample, an average of the reference sample is used.
Specifically, over the range of images taken, an average REF RGB
(denoted "AVE REF RGB") is determined for the reference sample. For
each individual image, the difference is calculated between the REF
RGB and the AVE REF RGB. This delta RGB is then added to the image
RGB to correct for any compensation in the camera. Thus if the
image is brighter than the average image, the difference is
subtracted from the sample values and vice versa.
[0164] In still another aspect, the reference sleeve has an end
plate which contains all tooth shades for a given manufacturer (so
that one sleeve is used for a particular manufacturer). Any image
therefore acquires the sample tooth as well as all the tooth
shades: and image processing commences on the one digital image.
This is advantageous in that camera color drift is compensated for
since all images are taken at the same time.
[0165] When determining tooth color, if the shade does not
correspond to an existing shade (such as A1, D4), a system 400 is
provided as shown in FIG. 15 which will create a recipe for
whatever shade the tooth is. Color digital information about the
tooth under test is sent to system 400 over a communication line
such as the Internet; and system 400 selects porcelain mixtures
from supply 402 to be sent and mixed within mixing subsystem 404.
Subsystem 404 dispenses the mixture into a capsule 406 for the
dentist, which administers the final mixture to the patient's
tooth.
[0166] The new shade material in carpule 406 is either provided
chair-side, or reported to the technician over the Internet 410 (in
which case, system 400 can be present at the technician's site). If
for example the dentist needs to use a composite material like
HELIOMOLAR by Ivoclar, and the desired shade is something between
C2 and C3, the system determines the new shade of "C2/C3", mixes
component composite materials accordingly, and dispenses to the
dentist a premixed carpule/cartridge 406 of material to be used on
that patient. Information to be sent to the lab can include a
recipe that will instruct the technician as to how to create the
new shade using whatever material is selected--porcelain, ceromer,
pressed porcelain, etc.
[0167] FIG. 16 illustrates in a block-diagram form the
configuration of the interactive network system in a preferred
embodiment. As shown, this system is implemented as a (preferably
website) server 1610, having access to one or more databases 1630
containing information about different aspects of dental
restoration. As noted, this information in a preferred embodiment
includes materials, procedures and preparation recipes related to
various dental restoration prostheses, and may include preparation
design, recommended burs to achieve such a preparation, recommended
temporization materials, cements that should be used with that
given material, instructions on how to use such a cement and where
to buy such materials, and others. In addition, database 1630 may
contain information about different dental procedures, and in
particular answers to commonly asked questions. In yet another
embodiment, the database may also contain patient histories, so
that a dentist (or a technician) having access to the system can
read the patient history regardless of where they are located
physically, provided that they have proper authorization to access
this information. The database may further be connected to external
information source(s) providing input from product manufacturers,
market research or others. In accordance with the present invention
there is no restriction on the type of database 50 design that can
be used.
[0168] In operation, users can access the service over a
communications network 1620, such as the Internet, using data entry
devices, designated 1640 in FIG. 16. Generally, devices 1640 can be
implemented as any color-display device capable of communicating
over the network 1620. In the preferred embodiment where the
network is the Internet, for example, such capability is provided
by browsers, as known in the art. Thus, a device 1640 can be a
conventional personal computer 14, as illustrated in FIG. 1. In
alternative embodiments that do not communicate over the Internet
such a device should have a capability to communicate over a
communications network, e.g., an intranet, as known in the art.
[0169] In a preferred embodiment, the server 1610 is a computer,
the type of which may range from a personal computer to a
workstation or a larger computer or a network of computers. The
choice of a specific computer system is based on known trade-offs,
and thus will not be discussed in further detail. In the preferred
embodiment, the server is Internet-enabled but it will be
appreciated that in alternative embodiments it can support another
network, e.g., an intranet. Broadly, the server 1610 comprises a
processor 1650 and random access memory (RAM) and read-only memory
(ROM), collectively designated 1670. The processor 1650 is adapted
to execute instructions in different computer languages and can
operate in different operating system environments, such as the
PC/Windows.TM. environment. In a preferred embodiment, the server
also has a data formatting device 1660 serving to provide interface
with the database(s) 1630. In various embodiments the server can be
provided with additional devices (not shown) such as a
point-and-click device (like a mouse), keyboard, a monitor and
various other devices, which may include, for example a printer 46.
Preferably, the server is equipped with means for connecting to
external communications media, and may include various connectivity
types, such as a LAN connection.
[0170] It will be appreciated that using the system shown in FIG.
16, different users 1640 can access information stored at the
network server (or to which the server has access). It will also be
appreciated that the system would enable direct communication
between users, such as on-line communication between a dentist and
a dental restoration laboratory, where the two sides can
simultaneously have access to a patient record, an image of tooth
in need for restoration or others. Naturally, if desired, such
communications can be established over dedicated lines although in
accordance with this invention it is desirable to use open systems,
such as the Internet because of the flexibility they provide.
Further, while they are shown separate for illustration purposes,
it should be apparent that the server 1610 can physically be
located at the dentist's (or laboratory) office.
[0171] The Web site can include one or more Web applications, each
providing specific information or functionality to the user. FIG.
17 illustrates a preferred embodiment of the interactive
computer-based network system, where clients connect to a server
across a communication network to obtain access to a Web
application. A general Web application consist of five major
components, a Web server 1760, an Application server 1750, a
database server 1740, a database 1730, and a Web browser (client)
1770. A Web server 1760 preferably runs specialized Web server 1760
software that supports Hypertext transfer protocol (HTTP) to handle
multiple Web requests and is responsible for user authentication in
case of intranet and extranet applications. An application server
1750 generally performs most of the application processing logic
and is also in charge of maintaining the state management and
session control logic that are required for an online system.
Preferably, the database server 1740 hosts Database Management
System (DBMS) and provides data access and management capabilities.
In a typical session, the Web server 1760 processes client requests
and sends HyperText Markup Language (HTML) pages back to the
client. When needed, a Web server 1760 connects to the application
server 1750 or database server 1740 to process the necessary logic
or database query and sends the result back to the Web server 1760.
This exemplarily arrangement does not mean that there must be an
application server 1750 for the Web application, and nor does it
imply that the Web server 1760, application server 1750, and
database server 1740 cannot all be located on the same machine. The
decision on architectural components is shaped by the requirements
of the application and the existing and future technology.
[0172] Preferably, the Web application is based on individual Web
pages, and is divided into clearly demarcated sections, allowing or
denying access as needed. Each portion of the application can have
its own Web page. As shown in FIG. 18, main application page 1820
is partitioned in to a patient page 1830 that provides access to
patient's record, and a restoration page 1840 that provides access
to information on dental restoration materials and tools. Each page
can include an appropriate user interface for gathering and
displaying data to the user, and may also include help right
alongside the application's interface and can contain links to
almost any other part of the application. Each page can do several
functions or just one. Special pages for specific users can be
added and accessed based on the user's identity, which can easily
be determined and managed, for example, by standard HTTP and Web
techniques such as authentication and the use of cookies.
[0173] A Web page and its embedded resources can be stored under
the Web server 1760 as they delivered (static Web page) or produced
dynamically at run-time, upon user request (dynamic Web Page). A
static Web Page can, however, be dynamic(active) on client-side
through the use of client-side scripting. The client-side scripting
are small programs that reside on the Web server 1760 that are
download with the Web page to bring interactivity. For example,
JavaScrpit, a client-side scripting language, can be employed to
facilitate manipulation of images and text, and gathering
information from forms.
[0174] Dynamic Web Pages are produced dynamically on server-side by
a server-side script. Examples of server-side script include Active
Server Page (ASP), Common Gateway Interface (CGI) script, Java
Active Pages (JSP), Hypertext Preprocessor (PHP). For example, in
the case of a Web database access, the Web browser 1770 sends a
database request to the Web server 1760. The Web server 1760 passes
the request using, for example, CGI to the application server 1750
where the Web-to database middleware may be located. The
application server 1750 then uses a database middleware such as
Open Database Connectivity (ODBC) to connect to the database. The
application server 1750 receives the query result and creates the
HTML formatted page and sends the page back to the Web server 1760,
the Web server 1760 then sends the page to the browser 1770. In one
preferred embodiment, the Web application includes both static and
dynamic pages such that to enable online communication between a
dentist, a practitioner, and other authorized users, where the
participants can simultaneously have access to an image of tooth,
patient records or any other appropriate information. Alternative
embodiment include cases where the Web application employs static
pages only.
[0175] While the invention has been described with reference to the
preferred embodiments, it will be appreciated by those of ordinary
skill in the art that various modifications can be made to the
structure, form and operation of the various embodiments of the
invention without departing from its spirit and scope, which is
defined in the following claims. To the extent necessary, the
applicant disclaims the subject matter of U.S. Pat. Nos. 6,786,726
and 6,575,751. Finally, for disclosure purposes, non-limiting
source code for use with certain aspects of this invention can be
found in U.S. Pat. No. 6,575,751 and is incorporated herein by
reference thereto to the extent required.
* * * * *