(12) United States Patent
`Lehmann et al.
`
`I 1111111111111111 11111 lllll 111111111111111 1111111111 111111111111111 11111111
`US006575751Bl
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 6,575,751 Bl
`Jun.10,2003
`
`5,690,486 A
`5,692,900 A
`5,725,372 A
`5,733,126 A
`5,745,229 A
`5,759,030 A
`5,798,839 A
`5,823,778 A
`5,851,113 A
`5,851,115 A
`5,871,351 A
`5,880,826 A
`5,938,446 A
`6,008,905 A
`6,030,209 A
`6,038,024 A
`6,049,743 A *
`6,111,650 A
`6,190,170 Bl
`6,217,334 Bl *
`6,244,863 Bl
`
`11/1997
`12/1997
`3/1998
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`4/1998
`6/1998
`8/1998
`10/1998
`12/1998
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`2/1999
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`8/1999
`12/1999
`2/2000
`3/2000
`4/2000
`8/2000
`2/2001
`4/2001
`6/2001
`
`Zigelbaum .. ... ... .. ... ... ... 433/29
`Fischer . ... ... ... ... .. ... ... ... 433/26
`Leon . ... ... ... ... ... .. ... ... ... 433/26
`Anersson et al. ........... 433/223
`Jung et al. .................... 356/73
`Jung et al. .................... 433/29
`Berner et al. ............... 356/402
`Schmitt et al.
`............. 433/223
`Jung et al. .................... 433/29
`Carlsson et al. ............ 433/215
`Jung et al. .................... 433/29
`Jung et al. .................... 356/73
`Andersson et al.
`......... 433/223
`Breton et al. ............... 356/402
`Panzera et al.
`............... 433/26
`Berner ....................... 356/326
`Baba .......................... 700/163
`Rawicz et al. ................ 56/402
`Morris et al. ............... 433/215
`Hultgren ..................... 433/215
`Rawicz et al. ................ 433/26
`
`FOREIGN PATENT DOCUMENTS
`
`(54)
`
`INTERACTIVE DENTAL RESTORATIVE
`NETWORK
`
`(75)
`
`Inventors: Maryann Lehmann, Darien, CT (US);
`Curtis A. Vock, Boulder, CO (US)
`
`(73) Assignee: Shade Analyzing Technologies, Inc.,
`Darien, CT (US)
`
`( *) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by O days.
`
`(21) Appl. No.: 09/523,152
`
`(22) Filed:
`
`Mar.10, 2000
`
`Related U.S. Application Data
`
`(63) Continuation of application No. 09/443,368, filed on Nov.
`19, 1999, now abandoned, which is a continuation of appli(cid:173)
`cation No. 09/411,920, filed on Oct. 4, 1999, now aban(cid:173)
`doned.
`( 60) Provisional application No. 60/106,920, filed on Nov. 3,
`1998.
`Int. Cl.7 .................................................. A61C 5/10
`(51)
`(52) U.S. Cl. ....................................................... 433/223
`(58) Field of Search ................................. 433/215, 218,
`433/223; 356/419; 705/1; 707/102, 10;
`700/106, 117, 118
`
`3/1990
`10/1992
`11/1992
`6/1986
`3/1991
`
`EP
`360657
`JP
`4301530
`JP
`4338465
`WO
`WO86/03292
`WO
`9102955
`* cited by examiner
`Primary Examiner-Todd E. Manahan
`(74) Attorney, Agent, or Firm-Winston & Strawn
`
`................. 356/402
`.............. 433/203.1
`
`.............. 433/203.1
`
`(56)
`
`References Cited
`
`(57)
`
`ABSTRACT
`
`U.S. PATENT DOCUMENTS
`
`3,861,044 A
`3,986,777 A
`4,247,202 A
`4,414,635 A
`4,518,258 A
`4,547,074 A
`4,575,805 A
`4,616,933 A
`4,623,973 A
`4,654,794 A
`4,692,481 A
`4,836,674 A
`4,881,811 A
`4,919,617 A
`4,978,296 A
`5,012,431 A
`5,124,797 A
`5,231,472 A
`5,240,214 A
`5,273,429 A
`5,313,267 A
`5,340,309 A
`5,373,364 A
`5,383,020 A
`5,430,811 A
`5,431,562 A
`5,440,496 A *
`5,452,219 A
`5,453,009 A
`5,498,157 A
`5,549,476 A
`5,587,912 A
`5,685,712 A
`
`1/1975
`10/1976
`1/1981
`11/1983
`5/1985
`10/1985
`3/1986
`10/1986
`11/1986
`3/1987
`9/1987
`6/1989
`11/1989
`4/1990
`12/1990
`4/1991
`6/1992
`7/1993
`8/1993
`12/1993
`5/1994
`8/1994
`12/1994
`1/1995
`7/1995
`7/1995
`8/1995
`9/1995
`9/1995
`3/1996
`8/1996
`12/1996
`11/1997
`
`................ 433/25
`Swinson, Jr.
`Roll ........................... 356/176
`Failes
`Gast et al.
`Broersma
`Hinoda et al.
`Moermonn et al. ......... 433/223
`Leveque et al.
`............ 356/416
`Hoffrichter et al.
`O'Brien ...................... 364/413
`Kelly
`Leguime et al. ............ 356/319
`O'Brien ...................... 356/323
`Antons et al.
`................ 433/26
`Antons et al.
`................ 433/26
`Stanziola .................... 364/526
`Williams et al. . . . . . . . . . . . . 358/225
`Marcus et al. .............. 356/402
`Thompson
`.............. 433/215
`Rekow et al.
`Macfarlane et al. ........ 356/405
`Robertson ................... 433/215
`Krzyminski ................ 356/323
`Vieillefosse
`Fukushima et al. . . . . . . . . . 382/254
`Andreiko et al. ............. 433/25
`Andersson et al.
`.... 364/474.05
`Dehoff et al. ............... 433/223
`Feldman ..................... 433/215
`Hall ............................ 433/26
`Stern . ... ... ... .. ... ... ... ... .. . 433/23
`Andersson et al.
`......... 433/215
`Fischer . ... .. ... ... ... ... ... .. . 433/26
`
`An interactive dental restoration method and system for use
`between a dentist and a dental restoration laboratory. The
`method includes 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 communi(cid:173)
`cations network to a dental restoration laboratory; and
`communicating a final treatment plan, including modifica(cid:173)
`tions to the preliminary treatment plan where necessary, to
`the dentist. The system includes a computer-based dental
`restoration system of a network server having a database
`storing information about materials, procedures and prepa(cid:173)
`rations concerning dental restoration prostheses; a commu(cid:173)
`nications 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 read(cid:173)
`able format. Preferably, the communications network is the
`Internet, and the information stored in the database com(cid:173)
`prises preparation diagrams, reduction dimensions, margin
`design and burs for specific dental restoration prostheses.
`Typically, the final treatment plan includes information
`about materials for preparing a dental prosthesis that satis(cid:173)
`fies the design criteria, and the dental prosthesis is then
`prepared for placement in the patient. This enables optimi(cid:173)
`zation of the dental restoration with significant savings in
`time and effort for the dentist, dental technician and the
`patient.
`
`20 Claims, 9 Drawing Sheets
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`3SHAPE 1023 3Shape v Align IPR2021-01383
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`

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`U.S. Patent
`
`Jun. 10, 2003
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`Sheet 1 of 9
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`US 6,575,751 Bl
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`
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`U.S. Patent
`
`Jun. 10, 2003
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`Sheet 2 of 9
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`US 6,575,751 Bl
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`FIG. 3
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`FIG. 4
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`U.S. Patent
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`Jun. 10, 2003
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`Sheet 3 of 9
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`US 6,575,751 Bl
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`U.S. Patent
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`Jun. 10, 2003
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`Sheet 4 of 9
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`U.S. Patent
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`Jun. 10, 2003
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`Sheet 5 of 9
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`U.S. Patent
`
`Jun. 10, 2003
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`Sheet 6 of 9
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`U.S. Patent
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`Jun. 10, 2003
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`Jun. 10, 2003
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`U.S. Patent
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`Jun. 10, 2003
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`US 6,575,751 Bl
`
`1
`INTERACTIVE DENTAL RESTORATIVE
`NETWORK
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`This application is a continuation of application Ser. No.
`09/443,368 filed Nov. 19, 1999, which is a continuation of
`application Ser. No. 09/411,920 filed Oct. 4, 1999, both now
`abandoned.
`
`TECHNICAL FIELD
`
`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
`
`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(cid:173)
`whether the restoration will be a crown, bridge, inlay, onlay 30
`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 sys(cid:173)
`tems for determining tooth color information based upon 35
`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 40
`facing an overload of information in trying to decide which
`materials and procedures are the best suited for their par(cid:173)
`ticular 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 45
`planning and delivering the best restorative dentistry
`possible, utilizing the most appropriate materials available
`today. The present invention now satisfies this need.
`
`2
`Generally, the dentist prepares the preliminary treatment
`plan and the design criteria include digital image represen(cid:173)
`tations of the dental restoration need. Thereafter, the pre(cid:173)
`liminary treatment plan can be forwarded to and evaluated
`5 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 communi(cid:173)
`cations network. Thus, the final treatment plan is not imple(cid:173)
`mented in the patient until after interim preparation infor-
`10 mation is transmitted to the laboratory and confirmed, thus
`avoiding rework or revision after the plan has been imple(cid:173)
`mented.
`Advantageously, the design criteria or the modifications
`thereto include proposed decay excavation, tooth
`preparation, or dental prosthesis color. When a dental pros-
`15 thesis such as a crown, bridge or replacement tooth is
`needed, the method includes verifying that the dental pros(cid:173)
`thesis 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
`20 the patient's teeth, the digital image representations include
`REAL IMAGE and REFERENCE IMAGES and the modi(cid:173)
`fications include correlation of a color selection for the
`dental prosthesis to match the REAL IMAGE. Furthermore,
`the design criteria can include tooth preparation and pro-
`25 posed 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.
`The invention also relates to a computer-based dental
`restoration system compnsmg 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 access(cid:173)
`ing information stored at the database over the communi(cid:173)
`cations 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, mar(cid:173)
`gin design and burs for specific dental restoration prosthe(cid:173)
`ses.
`Advantageously, the database further stores information
`concerning one or more patients having dental restoration
`needs. Also, the network server further comprises applica(cid:173)
`tion programs for enabling users to query the database
`regarding specific materials or procedures concerning dental
`restoration prostheses for confirmation, verification, modi(cid:173)
`fication or evaluation of the same, with the one or more
`computers at the dental office receiving answers from the
`50 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.
`The dental restoration laboratory also includes at least one
`computer that has access to the network server and the
`55 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 trans(cid:173)
`mitting the digital images to the computer(s) at the dental
`60 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.
`
`SUMMARY OF THE INVENTION
`
`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 treat(cid:173)
`ment 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 treat(cid:173)
`ment plan via a communications network to a dental resto(cid:173)
`ration 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 65
`restoration with significant savings in time and effort for the
`dentist, dental technician and the patient.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`These and other aspects of the invention should be more
`apparent from the following detailed description and draw(cid:173)
`ings in which:
`
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`US 6,575,751 Bl
`
`3
`FIG. 1 illustrates a shade analyzer system for capturing
`images in accord with a specific embodiment of this inven(cid:173)
`tion;
`FIG. 2 shows a representative image captured by the
`system of FIG. 1;
`FIG. 3 shows a representative image made up of pixels as
`captured by detector elements of the system in accord with
`the invention;
`FIG. 4 illustrates processing of the image of FIG. 3 using
`pseudo-pixels, in accord with one preferred embodiment of
`the invention;
`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;
`FIG. 6 illustrates a compression sleeve constructed
`according with a specific embodiment of the invention for
`capturing high-quality tooth images;
`FIG. 7 illustrates a source-to-tooth illumination, for
`improved image capturing in accord with one embodiment
`of the invention;
`FIG. 8 illustrates baffling and stray-light rejection within
`a sleeve in a specific embodiment of the invention;
`FIG. 9 illustrates different pseudo-pixel imaging 25
`mechanisms, optionally dependent upon tooth shape
`characteristics, used in accord with the invention;
`FIG. 10 illustrates a non-contact tooth imaging system,
`with stray light rejection, constructed according to a specific
`embodiment the invention;
`FIG. 11 illustrates another embodiment of a non-contact
`tooth imaging system in accordance with the present inven(cid:173)
`tion;
`FIG. 12 illustrates a digital image of a tooth;
`FIG. 13 illustrates a system for reimaging a tooth;
`FIG. 14 illustrates various tooth decay patterns and res-
`torations that can be addressed in accordance with the
`present invention;
`FIG. 15 is a schematic representation of the interactive
`network system of the invention.
`FIG. 16 is a block-diagram of the configuration of the
`interactive network system of the invention.
`
`DETAILED DESCRIPTION OF IBE
`INVENTION
`
`The present invention now 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 50
`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.
`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 address(cid:173)
`ing 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.
`
`10
`
`30
`
`4
`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
`5 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 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.
`After preliminary treatment plans are designed, and areas
`such as periodontal needs, decay excavation, endodontic
`concerns are addressed, the restorative needs are considered.
`15 If the treatment plan may include fixed prosthodontics
`(crowns and bridges), the clinical pictures are then for(cid:173)
`warded 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
`20 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.
`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.
`The site would provide access for users to 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,
`35 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
`40 contact to obtain such service. Beyond this, once the treat(cid:173)
`ment 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
`45 would scan his preparations and go to part of the site that
`would survey the teeth and assess reduction amount. This
`would typically be used in larger and more complex cases.
`The site would offer a number of features for communi(cid:173)
`cating 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
`55 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
`60 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
`65 patient.
`As the dentist accesses the site, he can immediately be
`asked certain questions regarding the patient's history. Typi-
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`6
`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
`5 benefit for both 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.
`Another advantage of real time evaluation is reduction.
`One of the most common errors in preparation is under(cid:173)
`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
`15 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
`20 to the tenth of a millimeter. Then, the dentist would compare
`this measurement to the given specifications of the prepa(cid:173)
`ration he had retrieved earlier from the preparation design
`area of the site to confirm compliance.
`Another use of the present interactive dental restoration
`25 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
`30 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.
`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.
`
`5
`cal 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 pro- 10
`viding the restoration lab with this additional information,
`all factors can be considered so that a sound, tailored
`treatment plan can be confirmed or recommended.
`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? (Information on
`how to obtain the color of the teeth is disclosed in the other
`application-please insert here) 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.
`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 35
`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.
`The issue of preparation design when planning to use that
`given material is also addressed by the site. Different mate(cid:173)
`rials 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 45
`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 or where it could be 50
`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.
`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 of the preparations can
`also be made by accessing a survey area of the site. This 60
`would evaluate the preparation for undercuts, under(cid:173)
`reduction, margin extension, and highlight areas that needed
`to be modified for optimum results.
`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 proce(cid:173)
`dures are correct, the lab would not have to be pouring and
`
`40
`
`The Color Determination Method
`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 a 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 Al 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
`55 computer, or other suitable storage device for further analy(cid:173)
`sis. FIG. 2 illustrates a representative digital image 30
`captured by the camera 12.
`As known in the art, each digital image has a plurality of
`picture elements, i.e., "pixels", corresponding to the ele(cid:173)
`ments 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
`65 be made up of 300 pixels in width across the tooth and 350
`pixels in height. In human teeth, any given tooth is approxi(cid:173)
`mately the same size, give or take a couple of millimeters,
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`Saturation-1-(3/R+G+B))*Min(R, G, B)
`
`Hue-Cos- 1((0.5*((R-G)+(R-B)))/((R-B)*(G-B)) 0
`
`·
`
`5
`
`)
`
`If S=0, Hue is meaningless
`
`If (B/lntensity)>(G/lntensity) then Hue-360-Hue
`
`8
`mine 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:
`R=Red value for pixel
`G=Green value for pixel
`B=Blue value for pixel
`Intensity=I/3 (R+G+ B)
`
`7
`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 5
`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 10
`background (i.e., the region outside of the tooth) and not o