WO1998015234A1 - Method for facilitating dental diagnosis and treatment - Google Patents

Abstract

A method for use in forming a preparation in a patient's jaw comprises the steps of: (a) generating electrically encoded data specifying pre-existing dental structure in the patient's jaw; (b) transmitting the data to a computer (24); (c) operating the computer (24) to generate on a monitor (34) connected to the computer a graphic representation of the pre-existing structure; (d) further operating the computer to predetermine an optimal position and an optimal orientation of a material removal tool (38) with respect to the pre-existing structure; and (e) additionally operating the computer to generate on the monitor a graphic representation of the tool in the optimal position and the optimal orientation relative to the pre-existing structure.

Description

METHOD FOR FACILITATING DENTAL DIAGNOSIS AND TREATMENT

Field of the Invention

This invention is directed to a series of related methods for facilitating dental diagnosis

and treatment More particularly, this invention relates to a method for use in forming a preparation in a patient's jaw This method is useful, for example, in anchoring a dental

implant in a jaw of a patient A related method entails conducting a practice operation on the patient In addition, this invention relates to a method for instructing and possibly monitoring an actual operation on the patient

This invention also relates to a method for providing information as to a patient's dental

condition, and more particularly, a method for producing an electronic chart of a patient's

dentition This invention further relates to a method for at least partially automatically making a dental diagnosis

Another method in accordance with the invention provides a computer with data

regarding a dentitious structure, e g , within a tooth, surrounding the tooth or within a bone, of

a patient Yet another method in accordance with the present invention serves in the formation

of a dentitious preparation Background of the Invention

U S Patent Application Serial No 507, 162 discloses a system for modifying the shape

of a three dimensional object such as a tooth in a patient's mouth The system includes a

pantograph type assembly for feeding to a computer digitized data representing surface

contours of the tooth The pantograph assembly includes a hand-held probe inserted into the

patient's mouth by a dentist The dentist manipulates the probe so that a stylus tip of the

instrument is held in contact with the tooth during tracing of a contour along the tooth A

pantograph extension outside the patient's mouth tracks the motion of the probe and particularly the stylus tip thereof, the motion of the pantograph extension being monitored by

cameras which transmit video signals to the computer

The computer shows on a monitor a graphic representation or image of the tooth This

image is generated from the digitized contour data and possibly also video data from an optical

probe In addition, the computer is preprogrammed with data on prosthetic dental appliances

and/or dental restorations, forms of which are provided in a kit These forms may be in a

variety of materials Images of these prosthetic appliances and/or restorations may also be displayed on the monitor under the control of the computer

Such a system, including its software, presents an opportunity to advance in additional

ways the daily practice of dentistry For example, pocket depth information is conventionally

obtained by visually reading a ruler on a stylus which is inserted into gingival pockets The

depth information is stored as numbers on a form or a sketch outlines on the form More

recently, the pocket depth information is available in the form of a chart print out upon manual

transference of the depth information to a computer Each such chart is a printed form with

outlines of squares, circles and rectangles representing the individual teeth positions in a dental

arch Horizontal lines crossing the tooth symbol outline serve as measured demarcations in reference to root shapes Roots are thus represented as two-dimensional shapes, outlined

below the two-dimensional rectangular or ovoid shapes of the crowns

The horizontal lines serve as printed references Each line is an increment for

measurements In this way, pocket depth information is mapped in chart form Various

inaccuracies inherent in the current measurement methodology are carried into the examination

data and are entered into the chart record as a subjective notation

An X-ray film of a tooth or other dentitious structure contains a great quantity of useful

information However, X-ray data is obtained separately from the peπodontal clinical data and both classes of data are read separately.

Further dental information obtained from direct observation include determinations of

mobility, gingival thickness, presence of bleeding, calculus, etc. These observations are separately and manually noted on a chart.

Accordingly, current dental diagnostic practice involves a variety of different

observational techniques; the results of the different observations are generally obtained or

recorded in different media and thus in different places. Currently, there is no integrated

diagnostic information store or single method of storing and presenting all the different observational results.

Another way of storing and presenting dental data is the study model. Study models are conventionally made of stone or plaster, although more recent technologies are based on more modern materials such as synthetic polymeric materials. Study models are necessary, or

at least useful, in the diagnosis and treatment of bone disease, gum conditions and missing teeth.

Dental implants constitute a relatively recent development in dental practice and/or

treatments. In an implant, the jaw bone of a patient is drilled to form a bore which receives a

blade or anchor for an implant crown. To produce a desired and proper osseo integration and

prosthetic and/or restorative placement of supra gingival restoration on the implant in its

functional occlusal position, the dental practitioner or surgeon must precisely control the

position, orientation and insertion of the blade or anchor. The ultimate position and

orientation of the blade must take into account the thickness of the bone at the area of the

implant, the proximity and orientation of adjacent teeth in the same jaw, and the location of

teeth in the opposing jaw. In proper conventional implantation surgery, two or three people

view the drill from different angles, to determine that the drilling is at a proper angle and location. Even under these circumstances, it is difficult to control the drilling operation so that

the position obtained and orientation of the implant blade is optimal or acceptable Objects of the Invention

A general object of the present invention is to provide a method for facilitating the

shaping or shape modification of an object, particularly a tooth or other dental structure

A more specific object of the present invention is to provide such a method which is

computer analyzed, guided or controlled

An additional object of the present invention is to provide a method for enabling a

dental practitioner to practice a technique without actually modifying or operating on a

patient's dentition or bone structure

Another, more particular, object of the present invention is to provide a method for

providing instantaneous feedback to a dental practitioner or student as to motions of a dental

instrument held as it is used or guided by the practitioner or student

Yet another particular object of the present invention is to provide a method for

automatically showing a dental practitioner or student a preferred tool position and orientation

in making a dental preparation

A further object of the present invention is to provide a method for storing together

and presenting together different dental observations and measurements, particularly,

observations and measurements made in different ways Thus, an object of the present

invention is to provide a method for facilitating the storage and presentation of dental

diagnostic information More specifically, it is an object of the present invention to provide an

electronic study model incorporating various classes of input, such as X-ray data and/or pocket

information An associated object of the present invention is to provide a method for facilitating the production of a study model (an electronic study model) An additional object of the present invention is to provide an improved method for

preparing a dental bone of a patient for receiving an implant A related object of the present

invention is to provide an improved method for positioning and orientation an implant blade

Yet another object of the present invention is to provide an improved method for

monitoring the formation, in a patient's jaw bone, of a bore for a dental implant

An associated object of the present invention is to provide a method for at least partially automatically monitoring the drilling in an implant operation Summary of the Invention

A method for use in forming a preparation in a patient's jaw comprises, in accordance

with the present invention, the steps of (a) generating electrically encoded data specifying

pre-existing dental structure for edentulous patients or those with at least one tooth, (b)

transmitting the data to a computer, (c) operating the computer to generate, on a monitor

connected to the computer, a graphic representation of the pre-existing structure, (d) further

operating the computer to piedetermine an optimal position and an optimal orientation of a

material removal tool with respect to the pre-existmg structure, and (e) additionally operating

the computer to generate, on the monitor, a graphic representation of the tool in the optimal

position and the optimal orientation relative to the pre-existing structure

Although this method has applications in virtually all areas of dentistry, it is especially useful in boring through hard or soft tissues and preparing a site for anchoring a dental implant

in a jaw of a patient In that situation, the pre-existing structure includes bone in the patient's

jaw, while the preparation comprises a bored structured form that has been in the jaw bone for

receiving a form or blade for the implant The optimal position and the optimal orientation of

the drilling or material removal tool are adapted to produce a desired position and a desired

orientation of the blade or anchor for the implant In this particular procedure, it is advantageous to generate, on the monitor, a graphic representation of the blade in the desired

position and the desired orientation relative to the bone and the tooth.

Pursuant to another feature of the present invention, the step of generating electrically

encoded data comprises a first step of generating digitized surface data and a second step of

generating digitized X-ray data. Both kinds of data are necessary for using the method to

implement a dental implant. The digitized surface data may include, for example, video surface

data and/or contour data generated with the aid of a probe. The X-ray data and the surface

data are correlated to produce a composite image showing both internal and external structures in the precise geometric relationships they have to each other in the patient's mouth. This

composite image may in turn be enlarged or expanded, modified or highlighted and shown in

different views or sections, for example, to facilitate comprehension of the patient's dental

structures.

In accordance with another step in a method pursuant to the present invention, the

computer is instructed to modify the optimal position and the optimal orientation of the dental

tool and is operated to generate, on the monitor, a graphic representation of the tool in the

modified position and orientation relative to the pre-existing structure.

A method in accordance with the present invention may be used to conduct a practice

operation on the patient. In such a practice operation, the dental practitioner orients a dental type instrument (e.g., a probe or a drill) in juxtaposition to the pre-existing structure at the

optimal position (shown on the monitor), such optimal position having been determined from information stored and/or recorded from standard practice procedures, or taught

methodologies, or computed and/or analyzed parameters based on text practice tutorial

systems. The computer is provided with electrical feedback or signals as to the actual position

and the actual orientation of the instrument The computer is then operated to automatically determine an angle between the optimal orientation and the actual orientation. The computer then alerts the dental practitioner as to the deviation, if any, between the instrument and the

optimal position (obtained from stored intelligences resources) and orientation thereof.

The instrument used by the practitioner in the practice exercise may take the form of a

practice instrument having a virtual tip, that is, a non-operational tip. Such a tip may be a

flexible stylus or a telescoping member.

Alternatively or additionally, a method in accordance with the present invention may be

used to instruct and possibly monitor an actual operation on the patient. Pursuant to this feature of the present invention, the tool (e.g., drill) is used to modify the pre-existing dental

structure to form the desired preparation (shown on the monitor). The computer is supplied

with electrical feedback as to motions of the tool and modifies the graphic representation on the monitor in accordance with motions of the tool to show modifications of the pre-existing

structure.

Advantageously, the computer provides the dental practitioner operating the dental tool

with an alert signal regarding deviation between an actual position and orientation of the tool

during the use of the tool on the patient and the optimal position and the optimal orientation,

as determined prior to the dental operation. The alert signal may take the form of an auditory

signal, for example, a verbal message or instruction synthesized by the computer. Alternatively

or additionally, the alert signal may include a visual indication provided on the monitor. An

alert signal may also be provided in a practice operation, to indicate to the operator a deviation

or a conformity of the practice instrument to the predetermined, recommended position and

orientation thereof.

Pursuant to another feature of the present invention, the pre-existing dental structure of

the patient is analyzed to determine position and orientation of a desired preparation Thus, for example, if the dental structure includes teeth on opposite sides of a missing tooth, the

teeth may be analyzed to determine their positions and orientations and the desired position, size and orientation of a crown to be attached to an implant blade or anchor at the gap The

analysis may include the determination of different virtual or imaginary structures, such as an

occlusal plance or a lingual buccal tilt, axes of symmetry and different parameters of a dental

arch

The analysis may supplemented with the steps of (a) at least partially automatically

accessing an electronic inventory of digitized prosthetic dental devices corresponding to

respective actual dental devices of an actual inventory, and (b) at least partially automatically

comparing the digitized prosthetic dental devices in different positions and orientations to the

pre-existing structure to determine an advantageous position and orientation of a

recommended dental device with respect to the pre-existing structure For example, in the event that an implant is to be inserted, the actual dental devices of the inventory include blades,

anchors, and angle elements for dental implants Pursuant to a further feature of the present invention, the step of operating the

computer to generate a graphic representation includes the step of operating the computer to

generate, on the monitor, graphic representations of a plurality of views of the pre-existing

structure At least one of the views may be generated by the computer upon interpolation of

the electrically encoded data For example, the thickness or breadth of the root of a tooth (as

visible in a distal to mesial view of the tooth) may be obtained by interpolating or calculating

on the basis of the root depth and width, as seen in an X-ray of the tooth from the buccal side

The interpolated dimensions are easily determined from available statistical information, such

as U.G Blacks's measurement data

The electrically encoded data advantageously includes X-ray data and contour or surface data as to the pre-existing structure

A method for providing information as to a patient's dental condition, and more

particularly, a method for producing an electronic chart of a patient's teeth, comprises, in

accordance with the present invention, the steps of generating first electrically encoded data as to external tooth surfaces in the patient's mouth and transmitting the data to a computer,

generating second electrically encoded data as to internal structures in the patient's mouth and transmitting the second electrically encoded data to the computer, and providing the computer

with electrically encoded coordinate reference data to enable the computer to correlate the first electrically encoded data and the second electrically encoded data The computer then

generates, on a monitor connected to the computer, a composite graphic representation of at

least some of the external tooth surfaces together with at least some of the internal structures

An electronic chart which results from practicing the above-described method stores

together and presents together different dental observations and measurements, particularly,

observations and measurements made in different ways More particularly, the electronic chart combines X-ray data and surface data into one storage medium and enables the presentation of

both kinds of data simultaneously An electronic study chart implemented in accordance with

the present invention presents internal structural features and external structural features

together, showing the geometric and dimensional relationships among the various structures

Clearly, the presentation and use of the dental information greatly facilitates the daily practice

of dentistry

It is to be noted, moreover, that an electronic study model in accordance with the

present invention can incorporate various classes of input More specifically, the electronic

study model can include the surface anatomies of dental structures, X-ray data pertaining to

the same structures, periodontal information such as pocket depths and pocket outlines, arch relationships and other bite information such as occlusal contact points and stress analyses.

Pocket information is obtained by contour tracing done with a probe in accordance

with the invention of U.S. Patent Application Serial No. 507, 162. Such a probe is capable of

collecting contour data beneath the gums. In accordance with the present invention, the

gingival contour data is integrated with X-ray data to provide a complete map of the pocket

lines and depths which is represented in graphic relation to bone contours.

The electrically encoded coordinate reference data for enabling the coordination of the

X-ray data and surface data may be produced in part by attaching an X-ray opaque reference element to a dental surface in the patient's mouth. The position of the X-ray opaque reference

element is then automatically recorded as part of the X-ray data and is additionally

incorporated into the surface or contour data, whereby the two kinds of data (external and

internal) may be correlated to produce an integral composite image.

Preferably, the X-ray opaque reference element is attached to the occlusal surface via

an X-ray transparent connector. Alternatively, where there are no teeth the X-ray opaque

reference element takes a saddle-like form and is laid on an edentulous gum surface in the

patient's mouth.

Pursuant to an additional feature of the present invention, the computer is operated to

distinguish different dentitious structures of the patient and to display the different structures in respective colors or in visually distinguishable textural patterns on the monitor. Such different

structures may include different substructures of a tooth. The computer uses various

techniques of pattern recognition to determine the different substructures. The patterns

include X-ray image density information, texture, shape or contour, and relative location.

This method is particularly valuable in conjunction with the method of providing an

electronic study model or chart. The chart thus shows various internal and external dentitious structures in different colors or textural patterns

In accordance with yet another feature of the present invention, the computer is

operated to determine points of contact between teeth of an upper jaw and teeth of a lower jaw

and to further determine stress areas in a bone of one of the upper jaw and the lower jaw The

computer may be provided with electrically encoded data as to forces exerted by the teeth of

the upper jaw and the teeth of the lower jaw during a biting action In that event, the computer

automatically calculates magnitudes of stress in the stress areas and can be programed to

provide diagnostic analysis

As mentioned hereinabove, a selected dimension of an internal dental structure may be

automatically calculated from a plurality of related known dimensions For example, the

thickness of a tooth root (in a direction from lingual to buccal), is calculated from a width and a depth of the root and the total contours and dimensions of the crown

According to a further feature of the present invention, pocket depths are at least

partially automatically determined through hand held probe trace-outs, the pocket depths being

displayed on the monitor

A method for making a dental diagnosis comprises, in accordance with the present

invention, the steps of (I) generating first electrically encoded data as to external tooth surfaces

in a patient's mouth and transmitting the data to a computer, (ii) generating second electrically

encoded data as to internal structures in the patient's mouth and transmitting the second

electrically encoded data to the computer, and (iii) operating the computer to generate, on a monitor connected to the computer, a composite graphic representation of the external tooth

surfaces together with the internal structures The computer is operated to select and match

stored information with input data so as to identify an anatomical condition of the patient's

dentition based on first electrically encoded data and the second electrically encoded data and to provide an indication of the determined anatomical condition

Preferably, the anatomical condition is displayed on the monitor in a predetermined

color different from a color in which the composite graphic representation is displayed.

Another method in accordance with the present invention provides a computer with

data regarding a dentitious structure of a patient. This method comprises the steps of (a)

piercing gum tissue in the mouth of the patient with a point of an instrument, (b) moving the instrument in the correctly angled direction so that the point contacts a bone surface underlying

the gum tissue, (c) generating a signal indicative of the position of the instrument point in

contact with the bone surface, and (d) feeding the signal to the computer This method is

particularly advantageous in the accumulation of data for forming a complete electronic

charting or study model of a patient's dentition and analyzing and/or computing space

dimensions of bone and/or tooth structures Also, this method is usef l, if not necessary, in

providing the practitioner with significant data to optimize the orientation and placement of a

dental implant. It is advisable in such operations to be aware of the bone contours or surfaces

Yet another method in accordance with the present invention serves in the formation of

a dentitious preparation and comprises the steps of displaying on a monitor a graphic representation in a first color of three-dimensional dental structure in a patient's mouth and also

displaying on the monitor, in a second color different from the first color, a graphic

representation of desired preparation of the dental structure, in combination with the graphic

representation of the dental structure A practitioner uses a material removal instrument (e.g.,

a drill) to remove material from a surface of the dental structure A graphic representation of

an actual modification of the dental structure achieved during that material removal step is then

displayed on the monitor, in combination with the graphic representation of the structure The

actual modification is shown in a third color different from the first color Pursuant to the invention, then, different stages of an actual preparation are displayable

on a computer monitor in different colors of a predetermined sequence of colors. Thus, it is

easy to determine at a glance the status of a preparation in progress The different colors or hues of the palette may, for example, represent sequential halves of the drill diameter distance

According to this particular feature of the present invention, a distance is calculated

between a first surface defined by the desired preparation and a second surface defined by the actual modification. The third color, i.e., the color of the modified surface, is then selected

from an electronic color palette wherein different distances are coded by respective colors, the

third color corresponding to the calculated distance Preferably, the third color is a

predetermined color to indicate a spatial difference between the actual modification and the

desired preparation

A method for charting a patient's dentition comprises, in accordance with the present

invention, the steps of (I) digitizing surfaces of at least one tooth in the patient's jaw, placing a

point of a dental instrument in contact with one of the surfaces, (ii) generating a first electrical signal encoding the location of the instrument point in contact with the one of the surfaces, and

(iii) verbally identifying a characteristic of the tooth at the contact location The verbal

identification is converted into a second electrical signal and, partially in response to the first

electrical signal and the second electrical signal, a chart of the teeth is produced including an

indication of the characteristic at the contact point location

The identified and displayed characteristic may take the form of a diagnostic condition

of the tooth at the contact location More particularly, the characteristic may be decay or a

filling

A method for preparing a tooth in a patient's jaw comprises, in accordance with the

present invention, the steps of (a) generating electrically encoded data as to surfaces of the tooth, (b) transmitting the data to a computer, and (c) operating the computer to generate, on a monitor connected to the computer, a graphic representation of at least one view of the

tooth. Also, an electrically encoded preparation preform is selected from resourced dental

information that has been programmed and/or organized into a memory of the computer. Upon the selection, the computer is operated to display the electrically encoded preparation

preform in overlay as an image on the graphic representation of the one of the views. Subsequently, a dental instrument is used to modify the tooth to assume the shape of the

electrically encoded preparation preform, the computer being automatically provided with

electrical feedback as to motions of the instrument. The graphic representation is modified in

accordance with motions of the instrument to show modifications of the tooth.

Pursuant to another feature of the present invention, the step of operating the computer to generate a graphic representation includes the step of operating the computer to generate,

on the monitor, graphic representations of a plurality of views of the tooth. At least one of

the views is generated by the computer upon interpolation of electrically encoded surface data For example, the thickness or breadth of the root of a tooth (as visible in a distal or mesial

view of the tooth) may be obtained by interpolating or calculating on the basis of the root

depth and width, as seen in an X-ray of the tooth from the buccal side. The interpolated

dimensions are easily determined from available statistical information.

A method for use in forming a preparation in a patient's jaw or tooth comprises, in

accordance with the invention, the steps of fixing a block of material relative to the patient's

jaw so that the block is disposed outside the patient's mouth, providing a practice dental type

instrument with a virtual operating tip and also providing a material removal tool enslaved to

the practice instrument so that the tool and the instrument move in tandem with one another

The practice instrument is then moved in a virtual or pretend operation as if to form the preparation in the patient's jaw. During the virtual operation, the tool is automatically operated via the enslavement thereof to the practice instrument, so that a recess is formed in the block.

An actual dental type instrument with an operative material removal tip is then used to form

the preparation in the patient's jaw. The actual dental instrument is coupled to a slave probe

which is inserted into and moved in the previously formed recess to thereby guide and limit

motion of the actual dental type instrument.

Brief Description of the Drawing

Fig. 1 is a block diagram of a system effecting a desired modification in the shape of a

pre-existing object such as a tooth to which access is restricted. Fig. 2 is a block diagram showing details of a surface data generating device shown in

Fig. 1.

Fig. 3 is partially a block diagram and partially a schematic elevational view of a

particular embodiment of the surface data generating device of Fig. 2.

Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 3.

Fig. 5 is a detailed schematic diagram of optical components in a grid projection assembly

included in the surface data generating device of Fig. 3.

Fig. 6 is a cross-sectional view, similar to Fig. 4, of another particular embodiment of

the surface data generating device of Fig. 2.

Fig. 7 is a schematic cross-sectional longitudinal view of yet another particular

embodiment of the surface data generating device of Fig. 2.

Fig. 8 is an elevational view of a distal end of the embodiment of Fig. 7, taken in the

direction of arrow VIII.

Fig. 9 is a plan view of a reference stylus usable in conjunction with the data generating

device of Figs. 3 and 7. Fig. 10 is a plan view of another reference stylus usable in conjunction with the data generating device of Figs 3 and 7

Fig. 11 is a partially diagrammatic perspective view of an embodiment of a contour data generating device shown in Fig 1

Fig. 12 is a partial perspective view, on an enlarged scale, of the contour generating

device of Fig. 11, showing its use with a dental patient

Fig. 13 is a partial perspective view, on an even larger scale, of another embodiment of

the contour generating device of Fig 1, showing its use with a dental patient

Fig. 14 is a perspective view of another contour data generating device usable in a

dentistry system

Fig 15 is a perspective view of drill movement control assembly

Fig 16 is a partial perspective view, on an enlarged scale, of a drill movement

restriction assembly, showing a tooth preparation preform on an even larger scale

Fig 17 is a partial schematic perspective view of a reference marker assembly

Fig 18 is a side elevational view, partially in cross-section, of a hand held instrument

usable in conjunction with a pantograph assembly illustrated in Figs 11-15, for gathering

parallel contour data

Fig. 19 is a cross-sectional view taken along line XIX-XIX in Fig 18

Fig 20 is a partial cross-sectional view taken along line XX-XX in Fig 19

Fig 21 is a partial cross-sectional view similar to that shown in Fig 20, showing a

modified parallel contour data gathering device

Fig 22 is a diagram showing a circuit of another parallel contour data gathering device.

Fig 23 is a schematic side elevational view of yet another parallel contour data gathering device Fig. 24 is a schematic side elevational view of a tooth as it would appear on a computer

monitor in accordance with the present invention, showing a desired preparation of the tooth

and an intermediate stage in the actual preparation.

Fig. 25 is a display on a computer monitor, showing optimal and actual orientations of

a dental instrument relative to a patient's dentitious surfaces.

Fig. 26 is a side elevational view, on an exaggerated scale of a dental instrument with a

telescoping virtual operating tip for use in a method in accordance with the present invention.

Fig. 27 is a side elevational view of another dental instrument for use in a practice or

virtual operation in accordance with the present invention.

Fig. 28 is a schematic top plan view of an instrument assembly being used in

performing a method in accordance with the present invention.

Fig. 29 is a side elevational view of a pair of molars bearing fiducial coordinate frame reference elements in accordance with the present invention.

Fig. 30 is a perspective view of another fiducial coordinate frame reference element in

accordance with the present invention.

Fig. 31 is a graphic representation, as would appear on a computer monitor in

accordance with the present invention, of internal and external structures of a pair of molars. Detailed Description of the Invention

As illustrated in Fig. 1, a computerized interactive system for producing a modification

in the shape of an object such as a tooth to which access is limited comprises a first data

generating device or assembly 22 for providing a computer 24 with electrically encoded data,

specifically, digitized video signals representing a three-dimensional surface of an object such

as a tooth. A second data generating device or assembly 26 is operatively connected to

computer 24 for transmitting thereto digitized signals containing information pertaining to a curvilinear contour on the surface of the three-dimensional surface of the tooth. In addition,

computer 24 may receive from a third data generating device or assembly 28 digitized input

signals relating to internal structures of the tooth being scanned Specifically, data generating

device 28 may take the form of an X-ray device such as used in current extra-oral or intra-oral

radiology or other methodologies and basically comprises a source 30 of X-ray radiation and a

detector 32 for receiving the X-ray radiation after it passes through a tooth and converting the incident radiation into a digital data stream fed to computer 24

As further illustrated in Fig. 1 , the computerized interactive dentistry system also comprises a display device 34 such as a monitor or stereo or holographic projector In

response to data signals, computer 24 generates a three-dimensional view on display of

monitor 34 of the tooth or teeth under examination More specifically, computer 24 is

provided with any commercially available stereophotogrammetric triangulation program for

calculating and displaying, on the basis of the video input signals from data generating devices

22, 26 and 28, three dimensional surfaces and contours of the tooth or teeth

The computerized interactive dentistry system of Fig 1 further includes another data

generating device or assembly 36 which provides computer 24 with digitized information that

can be displayed on video as to the location of the operative tip of a cutting instrument 38 such

as a dentist's drill relative to the three-dimensional structural features of the tooth. Data generating device 36 thus enables computer 24 to monitor modifications to the shape of the

tooth as those modification are being made in the tooth and to display such changes through its

monitor or video connection

The system of Fig 1 is further provided with any of several instruction input devices

such as a keyboard 40, a mouse (not shown), or a contact sensitive surface of monitor 34,

whereby an operator such as a dentist or dental technician may instruct the computer to display a desired tooth preparation on monitor 34. In addition, or alternatively, computer 24 may use input from drill data generating device 36 as instructions regarding, for example, the depth of a tooth preparation to be displayed on monitor 34.

Upon selecting a desired tooth preparation illustrated on monitor 34, the dentist

operates drill 38 to cut a recess into the tooth (in the case of a filling or inlay) or to remove an

outer layer of the tooth (in the case of preparing a form/shape for a crown or other prosthetic

restoration). Computer 24 monitors the location of the operating tip of the drill via data

generating device 36 and, if the drill approaches a boundary previously defined to the computer

from prior programed parameters entered, for example, during an interactive tooth preparation selection operation, then signals are generated that display color changes of material removal

information or interrupt the power provided to the drill via a supply 42 or alert the dentist via an electro-acoustic transducer 44.

As depicted schematically in Fig. 1 and discussed in greater detail hereinafter, data

generating device 22 includes a grid projection assembly 46 for optically imposing a grid onto

the surface of the patient's tooth. Data generating device 22 also includes an opto-electrical

transducer 48 such as a charge-coupled device for optically sensing or scanning the tooth

surface onto which the grid is projected by assembly 46. It is to be understood that the grid

pattern projected on the tooth surface need not be an orthogonal grid having two sets of lines

at right angles to one another, but may instead have the two sets of lines oriented at an acute

angle. Moreover, it is to be appreciated that a grid may be imposed onto the tooth surface by

other methods, such as adhesively attaching to the tooth surface a transparency provided with

a grid.

As further depicted in Fig. 1 and described in detail hereinafter, data generating device

26 comprises a pantograph-type component 50 which incorporates a stylus handle or holding member 52 and a pantograph extension 54 in turn including a pantograph arm 56 and a bridge element 58. Bridge element 58 connects pantograph arm 56 to stylus holding member 52.

Data generating device 26 further comprises at least a pair of opto-electrical transducers 60 and 62 preferably in the form of respective charge-coupled devices ("CCD"s). Pantograph

component 50 enables computer 24 to track, from outside the mouth, the motions of the tip of

the stylus member inside the mouth and even beneath the gum line.

Accordingly, data generating devices 22, 26 and 28 provide to computer 22 electrically

encoded data completely defining the structure of the tooth on which a dentist is working.

Computer 24 then "draws" and forms a graphic model of the tooth on monitor 34. At that

juncture the dentist instructs the computer to modify the displayed three-dimensional shape.

For example, the dentist may use keyboard 40 to input a command that a predefined tooth preparation, in graphic form, be overlaid on the three-dimensional graphic representation of the

tooth. The size of the tooth preparation relative to the tooth may be specified by entering a depth dimension via keyboard 40, data generating device 36, a mouse or a contact-sensitive

surface of monitor 34. Alternatively, computer 24 may be programed to automatically select a

possible tooth preparation in accordance with the data from data generating devices 22, 26 and

28. In accordance with yet another alternative procedure, the dentist may command the

computer to alter the graphic representation of the tooth, for example, by removing a layer of

several millimeters from a surface selected by the dentist or by removing a selected volume of

tooth from all five surfaces above the gum line to a contour below the gum line defined by the

second data generating device 26. The selection of the desired surface area may include

outlined boundaries made directly on the patient's tooth with the probe unit. These outline

boundaries may be combined with additional programed inputs that include a keyboard and/or a "mouse." As further depicted in Fig. 1 and described in detail hereinafter, data generating device

36 comprises a pantograph-type component 64 which incorporates drill 38 and a pantograph

extension 66 in turn including a pantograph arm 68 and a bridge element 70. Bridge element

70 connects pantograph arm 68 to drill 38. Data generating device 36 further comprises at

least a pair of opto-electrical transducers 72 and 74 preferably in the form of respective charge-coupled devices ("CCD"s). Pantograph component 64 enables computer 24 to track,

from outside the mouth, the motions of the tip of drill 38 inside the mouth and even inside a tooth.

Data generating device 36 may be the same as data generating device 26 with stylus

element 52 replaced by drill 38. Moreover, upon the selection of a desired tooth preparation

via computer 24, monitor 34 and an instruction input device such as keyboard 40, drill 38 is

used by the dentist to provide the displayed tooth preparation in the subject tooth. Computer

24 monitors the output signals of opto-electrical transducers 72 and 74 thereby tracks the

cutting motions of the operating tip of drill 38 inside the subject tooth. The excavations into

the tooth are displayed in real time on monitor 34 by computer 24.

As shown in Fig. 2, grid projection assembly 46 of data generating device 22 includes a

light source 76, a grid generator 78 and an assembly 80 of light guides and lenses for guiding

the grid light along a path through the data generating device and for focusing the grid light on

the surface of a subject tooth. The light subsequently reflected from the tooth surface is

gathered by further optical elements 82 and focused by those elements on the light sensitive

sensor surface of charge-coupled device ("CCD") 48. In response to a sensed pattern of light

intensities, CCD 48 generates and transmits to computer 24 a digitized video signal containing

information used by computer 24 to calculate the dimensions of the subject tooth and to

display the tooth's structure in a three-dimensional graphic representation on monitor 34. As shown in Fig. 3, the components 76, 78, 80, 82 and 48 of data generating device 22 may be housed in an elongate instrument frame or holder 84 including a handle 86 and a stem

portion 88 displaced laterally with respect to a longitudinal axis of handle 86.

In a preferred form of the grid projection instrument, illustrated in detail in Fig. 4,

holder 84 of Fig. 3 further includes a Y-shaped distal end portion 90 having a pair of hollow

legs 92 and 94 housing respective CCDs 96 and 98. Each CCD includes a respective photosensitive sensor array 96a and 98b and respective sequencing and processing electronics

96b and 98b. The sequencing and processing electronics 96b and 98b have input and output

leads 96c, 96d and 98c, 98d extending to computer 24 through stem portion 88.

Light containing a grid pattern is projected from Y-shaped distal end portion 90

through a focusing lens 100 mounted in a wall 102 between legs 92 and 94. The light

subsequently reflected from a subject tooth is focused on sensor arrays 96a and 98a by a pair

of lenses 104 and 106 disposed in legs 92 and 94. Lenses 104 and 106 may be considered

parts of focusing optics 82 (Fig. 2), while lens 100 is part of focusing optics assembly 80.

As shown in detail in Fig. 5, grid projection assembly 46 includes light source 76 (also

shown in Fig. 2), a pair of collimating lenses 108 and 110, grid generator 78 (see Fig. 2) in the

form of a plate provided with a grid pattern, and three mirrors or prisms 112, 114, 116 for

directing the grid-containing light rays through stem portion 88 (Fig. 3) to lens 100. Of course, frame or holder 84 may be provided with various movable mounting elements (not

shown) for adjusting the focuses of the various lenses.

Grid light may be guided through the grid projection instrument or frame 84 by

elements other than those illustrated in Fig. 5. As depicted in Fig. 6, an output array of light

beams is guided to lens 100 by a bundle 1 18 of optical fibers, while a pair of optical fiber input

bundles 120 and 122 receive incoming optical radiation focused on the input ends of bundles by lenses 104 and 108.

Fiber bundles 120 and 122 guide the incoming radiation to a pair of CCDs (not shown)

disposed in instrument frame 90 at a more proximal end of the frame, for example, in the

handle. Rather than two separate CCDs, the first data generating device 22 may include a

single CCD (not shown) disposed in the handle 84 (Fig 3) and means for directing light from

two separate optical pathways to the CCD.

As schematically shown in Figs. 7 and 8, a data generating device or optical probe 124

may incorporate a single CCD transducer 126 disposed in a handle 128 of an elongate instrument frame or casing 130. The handle 128 also houses a grid source 132. An optical

fiber bundle 134 guides a grid pattern from grid source 132 through a part of handle 128 and a stem portion 136 of frame 130 to a distal end of the probe. At the distal end, the grid pattern

is focused by a lens 138 onto a subject tooth, the reflected radiation pattern being focused by

another lens 140 onto the distal or input end of another fiber optic bundle 142 extending to CCD 126.

As shown in Figs. 3 and 7, frame member 84 and optical probe frame 130 are provided

with a stylus element 144 having an enlargement 146 at its distal end. Enlargement 146 is

disposable in the visual field of the respective optical scanning element or elements, whether

CCD 48, CCDs 96 and 98, or CCD 126, for providing computer 24 with a reference distance

or dimension at the surface of a subject tooth being scanned. Computer 24 is thereby able to

calculate absolute values for the dimensions of various surface features. Computer 24 measures distances by calculating the number of pixels in the respective sensor array (e.g., 96a

and 98a) which cover a feature whose dimensions are being determined. Inasmuch as

computer 24 is preloaded with the actual dimensions of enlargement 146, the computer is able

to compute actual distances by comparing the number of pixels correpsonding to enlargement 146 with the number of pixels corresponding to the features of the tooth.

Stylus element 144 is retractable into handle 86 or 128. Retraction may be

implemented either manually or automatically, for example, by a small motor and rack and

pinion (not illustrated) inside the respective handle. Moreover, stylus 144 is advantageously replaceable by other elements such as stylus 148 shown in Fig. 9 or stylus 150 shown in Fig.

10.

Stylus 148 is formed at a distal end with three prongs 152, 154 and 156 each having a

respective sphere 158, 160 and 162 at its free end. Spheres 158, 160 and 162 may have

different sizes for facilitating the measurement of anatomical distances by computer 24.

Similarly, stylus 150 has a plurality of prongs 164, 166, 168, 170 and 172 each provided at its

free end with an enlarged formation 174, 176, 178, 180 and 182 of a respective geometric

shape and a respective transverse dimension.

In using a data generating device equipped with stylus 148, a dentist places at least two of spheres 158, 160 and 162 on the surface of the tooth. Similarly, two enlarged end

formations 174, 176, 178, 180 and 182 are positioned in engagement with a tooth surface

during use of a data generating device incorporating stylus 150.

As depicted in Figs. 11 and 12, contour data generating device 26 (Fig. 1) comprises

three CCD cameras 184, 186 and 188 fixed to the free ends of respective adjustable mounting

arms 190, 192 and 194 in turm connected at their other ends to a pedestal member 196.

Contour data generating device 26 further comprises three transparent plates 198, 200 and 202

each provided with a respective grid 204 (only one designated in the drawing) and secured to a

common substantially L-shaped support arm 206. Support arm 206 is cemented or otherwise

attached to the jaw of a patient P prior to the use of the contour data generating device.

It is to be noted that although plates 198, 200 and 202 are illustrated as being orthogonally disposed and as having Cartesian orthogonal grids, it is not necessary for

effective calculation of distances and angles that the plates and grids be so oriented. An

ordinary modification of the stereophotogrammetric triangulation program is all that is

required for the system of Fig. 1 to function with plates 198, 200 and 202 and/or the grid lines thereof oriented at acute angles.

Any two CCD cameras 184, 186 and 188 correspond to opto-electrical transducers 60

and 62 of Fig. 1. Although three CCD cameras are preferred, in some instances two may be sufficient.

As further illustrated in Figs. 11 and 12, contour data generating device 26 includes

pantograph-type component 50. As described hereinabove with reference to Fig. 1 (includes

essentially a mirror image of illustrations in Fig. 11 and 12), pantograph component 50

incorporates stylus member 52, pantograph arm 56 and bridge element 58. CCD Cameras

184, 186 and 188 enable computer 24 to track orthogonal components of the motion of a predetermined point 208 on pantograph arm 56 against respective reference frame plates 198,

200 and 200, respectively. Because pantograph arm 56 is fixed with respect to stylus member 52, computer 24 is accordingly able to track, from outside the mouth of patient P, the motions

of the tip of the stylus member 52 inside the mouth and even beneath the gum line.

Pantograph component 50 is mounted to the free end of a linkage 210 including a

plurality of pivotably interconnected arm members 212. The base of linkage 210, like pedestal

member 196 is secured to a base 214.

Both stylus member 52 and pantograph arm 56 are rotatably secured to bridge element

58 so that they can rotate about respective longitudinal axes. Pantograph arm 56 is coupled to

stylus member 52 via an endless toothed belt 53 whereby rotation of stylus arm 52 about its

longitudinal axis by an operator results in a simultaneous rotary motion of pantograph arm 56. Accordingly, stylus member 52 is free to be moved by an operator along three translational axes and three rotational axes, the resulting motion being duplicated by

pantograph arm 56.

An alternative way for providing computer 24 with a reference frame against which to

measure motions of pantograph arm 56 and concomitantly stylus member 52 is illustrated in

Fig. 13. In the specific embodiment shown in Fig. 13, three CCD cameras 216, 218 and 220

are fastened to support member 206 in turn cementable, as discussed above, to the patient's jaw in which the subject tooth is rooted. Pursuant to this embodiment, no reference grids are necessary for computer 24 to monitor, via cameras 216, 218 and 220, the motion of

pantograph arm 56 and thus stylus member 52.

It is to be noted that the camera assembly of Fig. 13 essentially includes three pixel

arrays (not visible in the drawing) disposed in separate reference planes of a three dimensional

coordinate system, with the casings of the cameras serving in part to hold three lenses (not

designated with reference numerals) at pre-established distances with respect to the respective

pixel arrays to focus the light from the tip 208 of the pantograph arm on the pixel arrays. The

tip 208 of pantograph arm 56 may be provided with an LED or other marker element to

facilitate detection by the optical scanning assembly comprising cameras 216, 218 and 220.

As illustrated in Fig. 14, contour data may be generated by an alternative technique employing a multiple segment support arm 310 which extends from a fixed platform 312.

Support arm 310 includes segments 314, 316, 318, 320, 322 and 324 of which the first

segment 314 is connected to platform 312. Segments 314-324 are pivotably connected to one

another via six rotating joints 326, 328, 330, 332, 334 and 336. By incorporating six separate

junctions for rotational movement, an operating instrument (e.g., drill) 338 connected to the

free end of a last or outermost arm 324 can move with six degrees of freedom, specifically along three translational axes and three rotational axes.

Stationary platform 312 and segment 314 are connected at joint 326 to provide rotation

relative to one another about a substantially vertical axis. First segment 314 and second

segment 316 are coupled to one another for rotation about an axis which is essentially a

horizontal axis and which axis is co-extensive with the axes of segments 314 and 316. Joint 28

provides this rotational movement. Similarly, arm segments 316 and 318 are rotatably linked

via joint 330.

A probe or pantograph-type extension 344 is mounted to the outermost segment 324 and through a belt 346 rotates in synchronism with operating instrument 338. In this fashion,

probe 344 is slaved to operating instrument 338. Accordingly, a three-dimensional configuration or contour traced by the tip of operating instrument 338 will be replicated by a

tip of pantograph extension 344.

Each joint 326-336 is formed to have sufficient friction to allow the joint to hold a

position once placed therein. However, the friction of each joint is low enough so that

movement of the joint can be commenced fairly easily.

A plurality of digital encoders 340 are mounted to arm segments 314-324. Upon a

movement of operating instrument 338, encoders 340 transmit to computer 24 respective

signals encoding the amount of motion in the various six degrees of freedom. The monitoring device of Fig. 14 need not include pantograph extension 344 since motion tracking is

accomplished via the encoder output signals rather than optically.

Upon the transmission to computer 24 of sufficient data from surface data generating

device 22 and contour data generating device 26 (Fig. 1), computer displays partial or

complete graphic representations on monitor 34 of the subject tooth or teeth. The graphic

representations include the visible three-dimensional surfaces of each such tooth, as well as invisible base line data fed to computer 24 by contour data generating device 26. In addition, computer 24 may©be provided with electrically encoded data specifying internal structures such as the dentine inside each tooth and prior fillings or other prosthetic devices.

Upon viewing a tooth on monitor 34, a dentist may select a preparation which may be appropriate for the particular condition of the tooth. As described above, this selection may be

accomplished via an instruction corresponding to an electrically encoded tooth preparation

previously loaded into the memory of computer 24. Alternatively, the selection may be

implemented by inputing dimensional parameters via keyboard 40, including distances, angles,

planes and percentages. As another alternative, computer 24 may provide a menu selection on

monitor 34, selections being made from the menu via the keyboard, a mouse or a

touch- sensitive monitor screen. In another structural procedure, a dentist and/or operator may

use virtual preparation instruments to input specific percentages of tooth removal and to input specific boundaries and depths of tooth removal. The virtual preparation instruments include a telescopic stylus and/or drill substitutes. In yet another alternative procedure, computer 24

may be programed to recognize structural features of the tooth, such as its type, the location

and shapes of cavities and prior inlays or onlays and to automatically select a possible

preparation in accordance with the recognized features. The computer may be further

programed to vary the size of the preparation to correspond to the particular tooth. The

dentist would then view the selected preparation and alter it on screen by any of the

above-described instruction input techniques. Upon arriving at a final, desired preparation, the

dentist will inform computer via keyboard 40.

As discussed hereinabove, drill 38 (Fig. 1) is then used to remove a portion of the

subject tooth. Computer 24 may control the supply of power to the drill so that the drill is

operational only within the regions selected for removal during the interactive stage of the dental process. Accordingly, drill 38 will be de-energized until the cutting tip of the drill is in near engagement with a surface to be cut. Then computer 24 enables the transmission of

power from supply 42 to drill 38. Upon the subsequent approach of the cutting tip of the drill

to a defined boundary, as sensed preferably via data generating device 46 (Fig. 1), i.e., via

CCD cameras 184, 186, 188 or 216, 218, 220 monitoring a pantograph component 50, computer 24 automatically interrupts power transmission from supply 42 to drill 38

Fig. 15 illustrates a drill movement control assembly 230 similar in geometric design to

the linkage 226 of Fig. 14. However, the encoders 22 of that linkage mechanism have been

replaced in the movement control assembly of Fig. 15 with motors 232a-232f connected via

respective energization leads 234a-234f to computer 24 (Fig. 1). In addition, in drill

movement control assembly 230, the free end of a linkage 236 is connected to a pantograph

arm 238 rather than to a drill member 240. Drill member 240 is rigidly but removably coupled

to pantograph arm 238 via a U-shaped bridge 242 including a pair of legs 244 and 246 fastened to pantograph arm 238 and drill 240, respectively, and a transverse connector piece

248. Yet another leg member 250 is rigid with connector piece 248 and is telescopingly

received inside leg 246. A spring loaded release latch 252 serves to removably clamp leg

member 250 inside leg 246. Release latch 252 constitutes a safety mechanism enabling a

dentist to remove drill 240 from a patient's mouth if the motion of the drill therein in response

to operation of motors 232a-232f by computer 24 is not satisfactory to the dentist.

Upon the selection of a desired or optimum tooth preparation by a dentist and a

subsequent signal for commencing tooth cutting, computer 24 generates a series of signals

selectively energizing motors 232a-232f to move the operative end of drill 240 into

engagement with those regions of the subject tooth which are to be removed to achieve the

desired preparation. As described hereinabove, computer 24 controls the energization of drill 240 so that the drill is operative only in preselected zones in and about the regions of tooth to be removed

Limiting the motion of a dentist's drill 254 may be accomplished by selecting a tooth

preparation preform 256 from a kit of preparation preforms Preform 256 may be selected by computer 24, as described above, to confrom to a desired preparation or may be manually

selected. Preform 256 is cemented to one end of a support bracket 258, the other end of

which is attached to the patient's jaw wherein is rooted a tooth to be provided with the preparation of the selected preform A pantograph assembly including a drill 260, a bridge

member 262 and a pantograph arm 264 is then used to cut the tooth A tip on the pantograph

arm corresponding to the cutting tip of drill 260 is inserted into a cavity 266 in preform 256 (in

the case of a filling or inlay) Engagement of the tip of pantograph arm 264 with the walls of

cavity or recess 266 limits the concomitant motion of the drill, whereby the tooth is provided

with a recess having the same geometric structure as recess 266

Accordingly, a kit is provided of dental preparation preforms in different sizes and

shapes Some preforms correspond to shapes of inlays such as that shown in Fig 16 Other

preforms correspond to shapes of onlays or crowns The kit may also include prefabricated

restorations or restorative devices, that is, preformed inlays and onlays for attachment and/or

insertion to tooth surfaces upon preparation of those surfaces as described hereinabove

Computer 24 has a data memory loaded with electrically encoded data corresponding

to all of the preformed inlays and onlays in the kit More specifically, the predefined tooth

preparations selectable automatically by computer 24 or in response to instructions received

via keyboard 40 or otherwise all correspond to respective prosthetic or restorative inserts of

several predefined sizes

Accordingly, computer 24 operates to select a desired tooth preparation and to control the formation of that preparation in the subject tooth. Upon the completion of the preparation,

either the computer or the dentist selects the appropriately sized inlay or onlay or crown. If

necessary in a particular case, a selected preformed inlay or onlay or crown can be machined

prior to attachment to a tooth. Computer 24 may control the machining operations in a

conventional numerically controlled operation or may serve to limit the range of cutting

motions, as described hereinabove with reference to providing a tooth with the desired

preparation.

Fig. 17 shows an assembly 270 for supplying surface data generating device 22 (Fig. 1) with optically detectable reference distances or displacements at the surface of the object (such

as a tooth). Assembly 270 is attachable to the distal end of a dental probe such as instrument frame or holder 84 and comprises a holder member 272 made of transparent material and

provided with a linear array of equispaced parallel bores 274 each slidably receiving a

respective reference pin or stylus 276. Each stylus is pushed outwardly in a transverse direction relative to holder member 272 by a respective compression spring 278. In addition,

each stylus 276 is provided with a series of longitudinally equispaced striations or reference

marks 280.

The extensions of styli 276, i.e., the lengths to which the styli are pushed inside holder

member 272, are measured by computer 24 through video signals obtained via a pair of optical

pathways such as those illustrated in Figs. 4 and 6. Alternatively, two optical light receiving

elements such as prisms (not shown) may be placed on the same lateral side of the stylus array.

In using reference generator assembly 270 of Fig. 17, an operator such as a dentist

presses styli 276 against a tooth surface. Under the pressure exerted by the operator, styli 276

are pushed respective distances into bores 274 against the action of springs 278. The

displacement of each stylus 276 depends on and is a measure of a height of a respective surface element or zone of the tooth surface.

In most instances only a few (possibly as few as two) different positionings of stylus

assembly 270 are required for computer 24 to map the entire surface of the tooth under

observation. As illustrated in Fig. 18, a device for feeding to computer 24 (Fig. 1) contour data as to

the surface of an object such as a tooth comprises a hand-held dental instrument or frame 402

provided at a proximal end with an extension 404 removably insertable into a sleeve 406 which

forms a part of a pantograph assembly such as that illustrated in Figs. 11 through 15.

Instrument frame 402 is locked in a predetermined position and orientation to pantograph

sleeve 406 by a set screw 408.

At a distal end, instrument frame 402 carries two sets of pins 410 and 412 slidably

mounted to a nose portion 414 of instrument frame 401 in respective linear arrays extending at

an angle, preferably a right angle, with respect to a longitudinal axis 416 of instrument frame 402.

Proximally of nose portion 414, instrument frame 402 has a shoulder 418 in turn

formed with an opening or window 420 facing pins 410 and 412. A lens 422 is disposed at

window 420 for focusing incoming light on an input end of a bundle of optical fibers 424

extending to a video camera in the form of a charge coupled device ("CCD") 426 inside

instrument frame 402. CCD 426 is provided with conventional scanning circuitry 428 and output signal preprocessing circuitry 430. An output lead or multiple 432 extends from

preprocessing circuitry 430 to computer 24 (Fig. 1).

It is to be noted that other configurations of the operative components of the device of Figs. 18-20 are possible. For example, CCD 426 and its associated circuitry 428 and 430 may

be disposed at computer 24 or an intermediate location between the computer and instrument frame 402. In that configuration, optical fiber bundle 424 extends out from instrument frame

402 to the remote CCD. Alternatively, optical fiber bundle 424 may be omitted and CCD 426 positioned in juxtaposition to lens 422.

As depicted in Figs. 19 and 20, each pin 410 is hollow and contains an end portion of a respective optical fiber 434 extending from a light source 436 inside instrument frame 402 to a

mounting bracket 438 at an end of the respective pin 410. Each pin 412 is also hollow and

contains an end portion of a respective optical fiber 440 extending from light source 436 to a

mounting bracket 442 at an end of the respective pin 412. The distal ends of optical fibers 434 and 440, at mounting brackets 438 and 442, face lens 422, whereby the linear postions of pins

410 and 412 relative to nose portion 414 of instrument frame 402 may be instantaneously and

continuously monitored by computer 24 through the video signals received from CCD 426.

As further depicted in Fig. 20, each pin 410 is provided with a pair of spaced

perimetrically extending flanges 444 and 446. A helical spring 448 is compressed between a wall 450 of nose portion 414 and flange 444, thereby biasing the respective pin 410 in a direction indicated by an arrow 452. Flange 446 cooperates with another wall 454 of nose

portion 414 to limit the distance that a pointed end 456 of the respective pin 410 projects from nose portion 414.

Each pin 412 is provided with a pair of spaced perimetrically extending flanges 458 and

460. A helical spring 462 is compressed between a wall 464 of nose portion 414 and flange

458, thereby biasing the respective pin 412 in a direction indicated by arrow 452. Flange 460

cooperates with another wall 466 of nose portion 414 to limit the distance that a pointed end

468 of the respective pin 412 projects from nose portion 414.

In using the contour data gathering device of Figs. 18-20, a dental practitioner attaches

the instrument frame 402 to pantograph-type component 50 (Fig. 1) via sleeve 406 and set screw 408, thereby fixing the instrument frame and pins 410 and 412 with respect to

pantograph arm 56 which is monitored by opto-electrical transducers or video cameras 60 and

62. Pantograph component 50 enables computer 24 to track, from outside the mouth, the

translatory motion of an arbitrarily selected reference point on instrument frame 402 inside the

mouth of a patient. In addition, described hereinabove, pantograph assembly enables computer

24 to track the orientation of instrument frame 402 inside the patient's mouth. In this manner,

computer 24 is continuously informed not only as to the position of the arbitrary reference point, but also the orientation of a coordinate system or reference frame, exemplarily with the reference point as origin.

It is to be noted that other methods for providing computer 24 with data as to the

position and orientation of dental instrument 402 are possible. Instead of pantograph

assembly, for instance, the encoders and articulated support arm assembly 310 of Fig. 14 may

be utilized.

In addition to the data representing the location of an arbitrary reference point on

instrument frame 402 inside a patient's mouth and the three-dimensional orientation of the

instrument frame, computer 402 is supplied with a data stream from CCD 426 regarding the

instantaneous positions of sliding pins 410 and 412. The dental pratitioner presses pointed ends 456 and 468 of pins 410 and 412 against a dental surface and simultaneously draws

instrument frame 402 along that surface. During this motion, pins 410 and 412 slide back and

forth perpendicularly with respect to nose portion 414 in response to variations (pits and

cavities, projections) in the surface of the tooth being scanned. These reciprocating motions

tracing a plurality of parallel contours along the tooth surface are sensed by CCD 426 and

quantized by computer 24 to form parallel contour data utilizable by conventional CAD/CAM

programs previously loaded into computer 24. The positional tracking of pins 410 and 412 by CCD 426 and computer 24 is facilitated by light output of optical fibers 434 and 440. Computer 24 measures the motions of pins 410

and 412 relative to the arbitrary reference point. Moreover, computer 24 is able to

instantaneously correlate the incoming contour data stream(s) with the tooth surface being

scanned, owing to the incoming rotational data as to the orientation of instrument frame 402

inside the patient's mouth.

Pins 410 and 412 are shown in Fig. 19 as being aligned with one another along the

longitudinal axis 416 of instrument frame 402 However, contour data is collectible at an enhanced rate if the pins 410 of one row are staggered with respect to the pins 412 of the other

row. Such a two-dimensional array of pins 410 and 412 enables a greater pin density, thereby

increasing the amount of incoming contour data

Instrument frame 402 may be provided with a button (not shown) which, when pressed

by the dentist, provides computer 24 with a signal that contour data input is commencing

Fig. 21 depicts another pin or stylus 470 slidably mounted to nose portion 414 of

instrument frame 402 in substitution for pins 410 and/or 412 In pin 470, a light-emitting

diode 472 forms the light source for facilitating detection by CCD 426 (Fig. 18) and

monitoring by computer 24 Diode 472 is connected by a pair of leads 474 and 476 to two

brush-type terminals 478 and 480 which are in sliding contact with respective plates 482 and

484. Plates 482 and 484 are connected to opposite terminals of a direct-current voltage source 486 and are insulated from nose portion 414 by a buffer element 487

As further depicted in Fig. 21, each pin 470 is provided with a pair of spaced

perimetrically extending flanges 488 and 490 A helical spring 492 is compressed between wall

450 or 464 (see Fig. 20) of nose portion 414 and flange 488, thereby biasing the respective pin

470 in a direction indicated by an arrow 494 Flange 490 cooperates with wall 454 or 466 of nose portion 414 to limit the distance that a pointed end 496 of the respective pin 470 projects from nose portion 414.

Fig. 22 illustrates a portion of a pin or stylus 498 slidably mounted to a nose portion

(e.g. 414 in Fig. 18) of a dental instrument for providing computer 24 (Fig. 1) with digitized

data representing a surface contour on a tooth. As described hereinabove with reference to

Figs. 18-20, pin or stylus 498 is one of a plurality of identical stylii all slidably mounted to the

nose portion of the instrument frame in a linear or two-dimensional array for providing contour

data along a plurality of parallel planes. As further described above with reference to Figs.

18-20, the dental instrument carrying pins 498 is removably attachable to pantograph-type

component 50 (Fig. 1), whereby computer 24 is also provided with digitzed data representing

the location and orientation of a distal end of the dental instrument inside a patient's mouth during use of the dental instrument.

A pair of brush type contacts 500 and 502 are embedded in stylus 498 and operatively

engage in a sliding contact a plate 504 and a resistive element 506, respectively. A

direct-current voltage source 508 is connected across resistive element 506, while an output

voltage vO is taken across a portion of resistive element 506 depending on the distance that

stylus 498 is shifted with respect to the instrument. Output voltage vO thus represents the

displacement of stylus 498 and is fed to an analog-to-digital converter (not shown) prior to

being fed to computer 24.

As shown in Fig. 23, a parallel contour data gathering device includes an instrument frame or body 510. A nose portion 512 is pivotably attached to a distal end of frame 510 for

rotation about an axis 514. Nose portion 512 carries two linear arrays of pins or stylii 516 and

518 slidably mounted to the nose portion as described hereinabove with reference to Figs.

18-20. Pins 516 and 518 are partially longitudinally traversed by respective optical fibers 520 and 522 extending from a diode 524 in nose portion 512. Diode 524 in turn is energized by a source of electrical power via a pair of leads 526. Leads 526 include a pair of sliding or brush type contacts 528 for enabling the conduction of electrical energy to diode 524 over the

rotating link between frame 510 and nose portion 512. A reciprocating type motion of pins 516 and 518 which occurs as a dentist moves nose

portion 512 along a tooth surface is monitored by computer 24 via digitized video signals

arriving from a charge-coupled device ("CCD") and its associated circuitry 530. CCD 530

receives optical energy via a bundle of optical fibers 532 extending from a lens 534 in nose

portion 512.

The pivoting attachment of nose portion 512 to frame 510 facilitates the collection of

parallel contour data by enabling a dentist to orient nose portion at an angle (e.g. a right angle)

with respect to a longitudinal axis 536 of instrument frame 510. The angular orientation of

nose portion 512 particularly facilitates the collection of parallel contour data along a plurality

of parallel planes oriented at the afore-mentioned angle with respect to axis 536. Computer 24 is able to take the orientation of nose portion 512 into account by monitoring, via pantograph

assembly 50, the direction of motion of the distal end of instrument frame 510 during a data gathering motion thereof.

In addition to being preprogramed with digitized representations of dental preparation

preforms in different sizes and shapes, corresponding to actual preforms in a kit, computer 24

may be preprogramed with digitized images of intermediate stages in the preparation of teeth

to receive the preforms. Thus, each preform in the kit of preforms has in the data memory of

the computer 24 a plurality of digitized images, one image representing the preform itself and

other images representing intermediate stages or steps in the preparation of the tooth or teeth

with which the preform may be used. Upon the input into computer 24 of digitized data defining the surface of a tooth and

upon the selection of a tooth preparation or preform either automatically by computer 24 or in

response to instructions received via keyboard 40, computer 24 displays on monitor 34 an

image of the tooth, an image of the selected preparation, and an image of an intermediate stage or step in modifying the tooth to attain the selected preparation. These images may me shown

sequentially or simultaneously in juxtaposition to one another on the monitor. In addition, the

images may be modified, for example, in response to instructions from keyboard 40, to show different perspective views and/or cross-sectional views of the tooth, the selected preparation,

and the intermediate stage. Of course, more than one intermediate stage may be shown, if such

a multiple display is helpful in graphically explicating the modification of the tooth to achieve

the desired structure. It is to be noted that successive intermediate stages may be displayed

simultaneously in juxtaposition to each other. Alternatively, the successive stages may be

displayed sequentially.

Upon the display on monitor 34 of one or more intermediate stages in the modification

of a tooth to achieve the displayed preparation, the dental practitioner operates drill 38 (Fig. 1)

to modify the subject tooth initially to attain an intermediate stage and subsequently to reach the final desired preparation.

Of course, as discussed hereinabove with respect to the displayed graphic representation of the tooth, the displayed intermediate stage may be modified by computer 24

in response to instructions from the dental practitioner. Such an on-screen modification would

preferably be implemented prior to undertaking a tooth preparation operation.

It is to be noted that the above-described technique for using computer assistance in

modifying the shape of a tooth is especially useful to teach students preferred steps in

preparing a tooth. Computer 24 is preprogramed to store in encoded form a plurality of possible final modifications or preparations of a tooth and for each such final preparation at

least one respective intermediate stage in modifying the object at its surface to attain the

respective modification.

As described hereinabove, the modification of the tooth in accordance with the

preprogramed intermediate stage data may be implemented automatically by computer 24

operating under numerical control. Computer 24 thus uses the drill movement control

assembly 230 described above with reference to Fig. 15.

It is to be understood that the modification of the tooth may be implemented by a

machining or drilling process or more modern techniques such as laser etching. Pantograph assembly 50 or, alternatively or additionally, encoders and articulated

support arm assembly 310 provide a system and procedure for automatically and precisely

monitoring the motions of a dental instrument as it is being manipulated, either inside or

outside the mouth of a patient. As described hereinafter, the motions and/or positions and

orientations of the dental instrument may be recorded for subsequent playback or display on

monitor 34. This playback is advantageous, for example, for pedagogical purposes. A skilled

dentist or dentistry teacher uses a dental instrument to execute a preferred or ideal technique, and successive positions and orientations of the instrument are input into a computer via

pantograph assembly 50 and its attendant cameras or, alternatively or additionally, encoders

and articulated support arm assembly 310. Thus, these motion digitization devices are used to digitize the entire motion of a dental instrument or other tool as it approaches and begins work

on an object (e.g., tooth) to be modified (e.g., machined or drilled). To receive and store the

motion-encoding digital signals, computer 24 need only be programed to recognize when such

motion input is occuring. Recognition may be triggered, of course, by appropiate input, for

example, via keyboard 40 (Fig. 1). The initial recordation of a preferred manner of holding the dental instrument (which may be an operating instrument such as a drill or a non-operative instrument such as a

periodontic probe) may be implemented using a model or a representative tooth.

Upon the storage of motion data, computer 24 uses the data to illustrate the motion on

monitor 34. Such a depiction of instrument motion may take the form of a series of discrete

images of different successive positions and orientations of the dental instrument. The

successive images may be shown in rapid succession, as in a video presentation, or in slow

motion. Alternatively, the successive positions and orientations may be displayed simultaneously in juxtaposition on monitor 34. As yet another alternative, particularly in the

event that one position and orientation of the dental instrument is sufficient to demonstrate the preferred instrument use, computer 24 may be operated to show only that one position and orientation of the dental instrument. In addition, to further illustrate the manipulation of the

instrument, a graphic representation of a hand holding the instrument is shown on monitor 34.

In the event of several successive images, the hand's orientation may change together with the

orientation of the instrument.

Upon (a) the feeding to computer 24 of digitized information as to a surface of a tooth,

(b) showing on a display a graphic representation the tooth or a portion thereof and possibly a

graphic representation of a selected tooth preparation, and (c) the display on monitor 34 of one

or more images of a dental instrument in a preferred orientation for accomplishing a desired

modification of a tooth to achieve, for example, a selected preparation, the dental practitioner

or student manipulates drill 38 (Fig. 1) or a mock drill (e.g., with a telescoping or self-sinkable

drill bit) in an attempt to replicate the displayed position and orientation or series of displayed

positions and orientations. During this exercise, computer 24 advantageously monitors the

motion via pantograph assembly 50 or, alternatively, encoders and articulated support arm assembly 310 Computer 24 compares the actual motion with the ideal motion, as stored in

memory, and displays the results of the comparison on monitor 34 Such results may take the form, for example, of two differently colored images or sets of images In addition, arrows or

other pointers may be used to indicate parts of the actual motion which could be changed in a subsequent exercise to closer approximate the ideal motion Of course, an auditory alert signal

may be generated by computer 24 to indicate deviation from the ideal motion The alert signal

is advantageously sounded during the manipulation of the instrument As the instrument

deviates further and further from the ideal path, the auditory signal may become louder, or

change in pitch

The providing of feedback to a practitioner or student thus includes the step of

displaying a graphic representation of at least one actual position and orientation of the

instrument attained during the manipulation of the instrument The graphic representation can be displayed in juxtaposition to the image of the ideal position and orientation of the

instrument In providing feedback, computer 24 advantageously quantizes differences between the

ideal position(s) and orientation(s) and actual positions and orientations taken by the

instrument during manipulation of the instrument by the dentist or studnet The quantized

differences are indicated to that person via monitor 34

Fig 24 represents a graphic representation of a tooth 550 shown on computer monitor

34 (Fig 1) The external surfaces of tooth 550 are digitized and stored in internal memory of

computer 24, as described hereinabove with reference to Figs 1-23 In addition, as also

described above, computer 24 is operated to select a digitized or electronic preform 552 from

an inventory of preparations stored in computer 24 The inventory of electronic preforms

advantageously corresponds to a kit of actual preforms which may be inserted into actual preparations upon the formation of the preparations in patient's mouths by a dental

practitioner.

Upon selection of preparation 552, either automatically by computer 24 or by the

practitioner utiliizing keyboard 40 (Fig. 1), preparation 552 is displayed in overlay on tooth

550 on monitor 34. Preferably, preparation 552 is displayed in a different color from tooth

550.

Although Fig. 24 shows only a single view of tooth 550. It is to be understood that several views may be displayed on monitor 34 simultaneously. For example, tooth 550 may be

shown in buccal or lingual elevation, from the mesial direction or in plan view. In addition,

one or more cross-sectional views of tooth 550 may be provided. These views may be

presented as a matter of course on monitor 34 or, alternatively, the practitioner may instruct

computer 24 as to which views are to be displayed. Preferably, the tooth and preparation 552

have the same respective colors in all the various views.

Upon the display of tooth 550 and preparation 552 on monitor 34, the practitioner uses

drill 38 (Fig. 1) to modify the patient's tooth 550 pursuant to the desired preparation 552 as

displayed on monitor 34. During the modification of the actual tooth, the graphic representation on monitor 34 is altered to conform to the new tooth surfaces, as shown at 554.

The new tooth surface 554 is preferably displayed in a color different from the colors of the

original surfaces of tooth 550 and the surfaces of preparation 552.

To provide the practitioner with an additional indication of how close the prepared

tooth surfaces 554 are to the desired or target preparation 552, the color selected by computer

24 for the new tooth surface 554 corresponds to the distance between the actual tooth surface

554 and the desired preparation surface 552. As the distance between the actual tooth surface

554 and the desired preparation surface 552 changes during the dental operation, the color of new surface 554 on monitor 34 changes. To this end, computer 24 is provided with a

preprogramed sequence or palette of selectable colors which may, for example, represent

sequential half-drill diameter distances. Thus, it is easy to determine by a glance at monitor 34

the status of a preparation in progess. Of course, computer 24 is programed to continuously

calculate distances between the actual tooth surface 554 and the desired preparation surface

552 and to select the color of new surface 554 in accordance with the colors of the palette.

Fig. 25 shows a display on monitor 34 of three views of an optimal position and orientation 556 of a drill (not separately enumerated) for cutting into a patient's mandible 558

(or any bone structure) a bore 560 for receiving an anchor or blade (not shown) of an implant.

Fig. 25 also illustrates in dot-dash phantom outline an actual position and orientation 562 of

the drill during an actual operation, or of a virtual instrument during a practice or trial run.

More specifically, a first screen portion 564 illustrates a buccal or lingual elevational

view of a pair of molars 566 and several front teeth 568, as well as a part of jaw bone 558. In

a second screen portion 570 is depicted a view of molars 556 from the mesial direction. In a

third screen portion 572 is a top plan view of molars 566, front teeth 568 and bone 558. As

discussed hereinabove with reference to Fig. 24, other views may include cross-sectional views

which are dervied by computer 24 via interpolation techniques.

The external surfaces of teeth 566 and 568 are measured or digitized as described

above with reference to Figs. 1-23. In addition, stylus or probe member 52 (Fig. 1) is used to digitize the surface of jaw bone 558. To that end, stylus member 52 is provided with a sharp

stylus 574 (Fig. 1) having a length sufficient long to penetrate gum tissue and contact the bone

surface. Upon achieving a contact, the practitioner signals computer 24, e.g., via keyboard 40.

The dental practitoner repeats the procedure of piercing the gum tissue in a region about a

desired implantation site and taking point data until enough data has been collected for computer 24 to map, via interpolation techniques, the entire surface of bone 558 about the implantation site.

The exact placement of bore 560 may be determined to a greater or lesser extent

automatically by computer 24. Computer 24 makes this determination in accordance with (a)

surface data as to molars 566 and front teeth 568, (b) surface data as to opposing teeth (bite

information, obtained as described hereinafter particularly with reference to Fig. 31), (c) the

dimensions and shape of jaw bone 558, and (d) the location of internal bone structures, such as

blood vessels such those which occupy inferior alveolar canals, or sinus structures, which are

to be scrupulously avoided during the drilling operation. It is to be noted that computer 24, because of the digitized locations of and shape data on the canals and sinuses or other

anatomical structures, is in an excellent position to determine the optimal angle and depth of anchor-receiving bore 560.

Data as to internal structures (e.g., blood vessel canals) of jaw bone 558 may be

obtained via X-ray data generating device or assembly 28 (Fig. 1). Such internal structures can

be displayed on monitor 34. The coordination of the X-ray data as to internal structures and

the data collected via optical data generating device or assembly 22 and pantograph data

generating device or assembly 26 is implemented as described hereinafter with reference to Fig.

29.

As stated above, computer 24 calculates an optimal position and orientation 556 of a drill for forming bore 560 and displays that optimal position and orientation preferably,

although not necessarily, in three orthogonal views such as the buccal or lingual elevational

view of screen portion 564, the mesial direction view of screen portion 570, and the top plan

view of screen portion 572. To enable a dentist or oral surgeon to practice holding the drilling

instrument in the correct position and orientation 556, the drill is attached to the pantograph assembly (e.g., like cutting instrument 38 in Fig. 1). Alternatively, a practice or virtual

instrument as those discussed hereinafter with reference to Figs. 26 and 27 may be attached to the pantograph assembly.

The dentist holds either the actual drilling instrument or a practice instrument in the

patient's mouth and manipulates it while watching monitor 34. On monitor 34, the position and orientation 562 of the manipulated instrument is represented in real time in a manner

detectably different from the representation of the optimal position and orientation 556 of the

drill. For example, the actual position and orientation 562 of the actual or practice instrument

may be shown in a different color or in phantom outline, as in Fig. 25.

As shown in Fig. 25, a dentist or oral surgeon is provided with immediate feedback,

from at least two different directions, of the position and orientation of an actual or virtual drill relative to the patient's tooth and bone surfaces. This feedback also includes an indication of

the actual position and orientation 562 relative to a predetermined optimal position and orientation 556. The indication may include not only an illustration of the relative positions

and angles but also numerical angular designations (e.g., 0°, -5°) of the differences between

the actual position and orientation 562 relative the predetermined optimal position and

orientation 556.

As further illustrated in Fig. 25, the display on monitor 34 may also include one or

more screen areas 580, 582 and 584 wherein the representations of the actual position and

orientation 562 and the predetermined optimal position and orientation 556 are simplified to

lines 588, 589 and points 590.

The feedback as to divergences between actual position and orientation 562 and

predetermined optimal position and orientation 556 may alternatively or additionally take an aural form, instructions or information being communicated to the dentist or surgeon via electro-acoustic transducer 44 (Fig. 1). If the instructions or information is in the form of

words, those words may be generated with the aid of well known, conventional speech

synthesis software and hardware (not illustrated).

A virtual instrument for use in practice or trial runs is depicted in Fig. 26. The instrument includes a handle 592 attachable to pantograph component 64 (Fig. 1) and a virtual operating tip 594 comprising a telescoping member. Telescoping operating tip 594

enables the dentist or surgeon to practice a drilling operation on the patient without actually penetrating the patient's tooth or tissues (e.g., gingiva, edentulous gum tissue or bone tissue).

As discussed above, the dentist or surgeon watches monitor 34 during the practice or trial run,

thereby obtaining immediate feedback as to the proper manipulation of the instrument.

Upon satisfactory practice, the dentist or surgeon replaces the practice instrument (Fig.

26) with an implant burr or drill and proceeds with the actual operation. Of course, computer

24 continues to provide both visual and aural feedback to the operator during the actual

surgery. The supplementary techniques described above for computer monitoring of a dental

operation are available in an implant operation. Computer 24 may terminate power to the

drilling instrument if the angle of penetration deviates more than a preset amount from the

predetermined optimal orientation. Alternatively, the drilling operation may be conducted

automatically by computer 24 in accordance with the principles of numerical control and with

the equipment described above with reference to Fig. 15.

As also described earlier, the dentist or surgeon interacts with computer 24 to

determine the optimal position and orientation 556. A selection made by computer 24 may be

modified by the practitioner. Moreover, the selection by the computer may be made in

accordance with a digitzed inventory of anchors and angle. It is to be noted that this technique of practice or trial run operations may be performed

in areas of surgery other than dental surgery. Generally, the necessary steps include (a)

scanning body structures internal to the patient, (b) digitizing the internal structures in response

to the scanning, (c) displaying an image of the internal structures in response to the digitized

signals, (d) providing a practice surgical instrument with a virtual operating tip, (e) moving the

surgical instrument outside of the patient in a simulation of actual surgery on a portion of the

internal structure, (f) automatically monitoring the instrument during the step of moving, and (g) displaying a representation of at least the operating tip of the instrument in overlap with the image of the internal structure during the step of moving.

As shown in Fig. 27, practicing an implant procedure may be undertaken with a dental

instrument provided with a holder 596 to which an implant anchor 598 is attached. This

provides the practitioner with further visual and tactile feedback as to the position and

orientation that the anchor will have upon implantation into jaw bone 558 of the patient. The

instrumentation shown in Fig. 27 may be modified for placing an implant anchor into a

telescoping frame so that actual pressing of the implant into tissue provides a graphic display of

the virtual position of the implant as it would be inserted.

As illustrated in Fig. 28, a practice or trial run of an implant drilling operation may be

performed with a practice or virtual instrument 600 mounted to a pantograph assembly 602 which also holds a drill 604. Drill 604 is enslaved to virtual instrument 600, as described

hereinabove with respect to Figs. 1 and 14, so that motions of virtual instrument 600 are

duplicated by drill 604. During motions of virtual instrument 600 towards jaw bone 558, as if

an actual operation were being performed, drill 604 cuts a bore into a block of acrylic material

606 which has been fastened to the patient's jaw by conventional bonding techniques.

Upon the satisfactory completion of a practice operation, block 606 is provided with a hole (not shown) matching the bore 560 to be formed in the patient's jaw bone 608. The hole

in block 606 can then be used as a template to guide, limit or control the motions of an implant drill during an actual operation on the patient's jaw bone 558. Prior to the actual operation, of

course, virtual instrument 600 is replaced by an actual implant drill while a drone or probe is

substituted for drill 604 in pantograph assembly 602.

As described hereinabove, the system of Fig. 1 includes (a) optical data generating

device or assembly 22 for providing a computer 24 with electrically encoded data, specifically,

digitized video signals representing a three-dimensional surface of an object such as a tooth, (b) pantograph data generating device or assembly 26 for providing computer 24 with digitized

signals containing information pertaining to a curvilinear contour on the surface of the three-dimensional surface of the tooth, and (c) X-ray data generating device or assembly 28 for

providing computer 24 with digitized input signals relating to internal structures of the tooth

and surrounding anatomy being scanned.

In order to coordinate the data from optical data generating device or assembly 22

and/or pantograph data generating device or assembly 26, on the one hand, with the data from

X-ray data generating device or assembly 28, on the other hand, it is desirable to provide

computer 24 with reference data to establish a common coordinate system for both the

external surface data from devices or assemblies 22 and/or 26 and the internal structural data

from X-ray device 28. As illustrated in Fig. 29, this common coordinate system may be

established via the utilization of fiducial reference elements 610 each comprising an X-ray opaque or X-ray detectable portion 612 in the form of a cross-bar of a T shape. The X-ray

opaque cross-bar 612 is connected to an X-ray transparent stem 614 in turn cemented to the

occlusal surface of a respective tooth 616 at 618. The locations and orientations of reference

elements 610 with respect to the external surface data are determined via the use of pantograph data generating device or assembly 26. That device merely traces the shape of cross-bar 612 or a predetermined feature on the surface of the respective reference element 610. The teeth to which the particular coordinate-system reference elements 610 are attached

may be entered in computer 24 via keyboard 40. In addition, the identities of the teeth are

communicated to computer 24 via X-ray data generating device or assembly 28. Reference

elements 610 are provided with distinguishable identifying features detectable via X-ray data

generating device or assembly 28. Such identifying features may take the form of a bar code

or other markings.

Although Fig. 29 shows T-shaped reference elements, it is to be understood that

numerous other shapes may be used.

Fig. 30 depicts a coordinate-system reference element 620 in the shape of a saddle

mounted on a gum surface 622. Reference element 620 may include one or more X-ray opaque segments or strips 624. The strips may include a bar code or other identification corresponding to the location of gum surface 622.

Data fed to computer 24 via X-ray data generating device or assembly 28 may

comprise two or more views of the same tooth from different angles. In that event, computer

24 can use a stereophotogrammetric triangulation program to determine the three-dimensional

shapes and dimensions of structures internal to the subject tooth. Alternatively, the thicknesses

of internal structures such as roots and nerves may be calculated by computer 24 from the

X-ray detectable dimensions and shapes (e.g., widths and lengths) and from statistics

correlating the width and length dimensions with thickness dimensions for the diferent kinds of

internal tooth structures. It is to be understood that roots are considered internal structures in

this regard because of their dispositions inside the jaw bones.

As yet another alternative, the thicknesses of internal structures may be determined by computer 24 by from X-ray detectable densities. The gray level of a particular feature is

therefore indicative of the thickness of that feature.

Computer 24 analyzes external surface data from optical data generating device or assembly 22 and/or pantograph data generating device or assembly 26 and internal structure

data from X-ray data generating device or assembly 28 to determine three-dimensional dentitious structures. Computer 24 may be programed additionally to recognize shapes, X-ray

densities, textures, and relative locations of different structures in order to identify the different

internal tooth structures. Upon identifying the different structures, computer 24 reproduces the structures in graphic form on monitor 34, as illustrated in Fig. 31.

More particularly, Fig. 31 illustrates an image which computer 24 provides on monitor

34. The image in Fig. 31 is a lingual or buccal elevational view of a pair of molars 626 and

628. Preferably, the different structures of molars 626 and 628, such as the root 630, the pulp

632, the gum 634, the bone 636, and the enamel 638 are displayed in different colors. Alternatively, cross-hatching, different line types and/or different textures may be used to

distinguish the different structures.

In addition to natural substructures, computer 24 is programed to detect and display on

monitor 34 abnormal conditions such as a filling 640 in molar 626 and decay 642 on molar

628. These abnormal conditions may be indicated in respective colors different from the colors

used to indicate the normal tooth substructures. In addition, a circle 644 may be used to

highlight a tooth condition, such as decay 642, particularly if the condition is small and possibly

undetectable on monitor 34.

As described hereinabove with reference to Fig. 24, computer 24 may display, at the

option of the user, many different views of the subject teeth 626 and 628. The views may be

elevations or plan views or cross-sections. One or more views may be shown one the same screen at once The view of the subject tooth or teeth 626, 628 may be a perspective view which is rotating in space, as shown on monitor 34

Different numbers of teeth may be shown on monitor 34 depending on the preference

of the user One tooth may be selected or even all of the teeth of one or both jaws In the

latter case, the information displayed advantageously includes bite information such as the

locations of contact between the occlusal surfaces Such areas of contact may be highlighted by circles 646 (Fig 31) or by other means

Computer 24 is additionally programed to calculate stresses on jaw bones and root

structures, depending on the locations of the bite points on the different teeth, the types and

sizes of the teeth and statistics as to bite forces The statistical information may be replaced by

measurements of a particular patient's bite

Another dentitious dimension which may be determined and displayed on monitor 34 is

the depth of gingival pockets 648 (Fig 31) Pantograph data generating device or assembly 26

is particularly adapted to measure pocket depths and collect subgingival data The pocket

depths may be calculated by computer 24 in response to the digitized contour data from

pantograph data generating device or assembly 26 and displayed in numerical or other coded form on monitor 34

As shown in Fig 1, computer 24 is connected at an input to a voice-recognition unit

650 which in turn receives input signals from an acousto-electric transducer 652, for example,

a microphone Transducer 652 and voice-recognition unit 650 are used by a practitioner to

facilitate the input of data into computer 24 Generally, as the practitioner is providing

computer with surface data from optical data generating device 22 or pantograph data

generating device 26 or X-ray data from X-ray data generating device 28, the practitioner may

be vocally identifying the teeth and/or the surfaces to which the surface data or X-ray data pertain. For example, the practitioner might say "tooth number 24, occlusal." In addition, as

the dentist identifies a condition or abnormality such as a filling or decay, these characteristics

may also be identified to the computer. For example, upon pointing to a particular location

with stylus or perio-probe for coordinate output then in conjunction with this data generating device 26, the practitioner will say "decay, tooth number 18, buccal" to facilitate identification

of the abnormality by the computer.

These conditions are then depicted on monitor 34 as described hereinabove with

reference to Fig. 31. The convenience and facility of vocalization to diagnosis and charting

may be readily understood.

Although the invention has been described in terms of particular embodiments and

applications, one of ordinary skill in the art, in light of this teaching, can generate additional

embodiments and modifications without departing from the spirit of or exceeding the scope of

the claimed invention. Accordingly, it is to be understood that the drawings and descriptions

herein are proferred by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.

Claims

1 A method for preparing a tooth in a patient's jaw, comprising the steps of

generating electrically encoded data as to surfaces of said tooth,

transmitting said data to a computer,

operating said computer to generate, on a monitor connected to said computer, a graphic representation of at least one view of said tooth,

selecting an electrically encoded preparation preform from a memory of said computer, additionally operating said computer to display said electrically encoded preparation preform in overlay as an image on the graphic representation of said one of said views,

using a dental instrument to modify said tooth to assume the shape of said electrically

encoded preparation preform,

providing, to said computer, electrical feedback as to motions of said instrument, and

modifying said graphic representation in accordance with motions of said instrument to

show modifications of said tooth

2 The method recited in claim 1 wherein said step of operating said computer to

generate a graphic representation includes the step of operating said computer to generate, on

said monitor, graphic representations of a plurality of views of said tooth

3 The method recited in claim 2 wherein at least one of said views is generated by said

computer upon interpolation of electrically encoded surface data

4 The method recited in claim 1 wherein said step of generating electrically encoded

data includes the step of gathering contour data

5. The method recited in claim 1 wherein said step of generating electrically encoded

data includes the step of producing a video signal.

6. The method recited in claim 1 wherein said step of generating electrically encoded data includes the step of collecting X-ray data as to said tooth.

7. The method recited in claim 1 wherein said view is a cross-sectional view of said

tooth.

8. A method for use in forming a preparation in a patient's jaw, comprising the steps of:

generating electrically encoded data specifying pre-existing structure;

transmitting said data to a computer;

operating said computer to generate, on a monitor connected to said computer, a

graphic representation of said pre-existing structure; further operating said computer to predetermine an optimal position and an optimal

orientation of a material removal tool with respect to said pre-existing structure; and

additionally operating said computer to generate, on said monitor, a graphic

representation indicating said optimal position and said optimal orientation relative to said

pre-existing structure.

9. The method recited in claim 8 wherein said pre-existing structure includes bone in

the patient's jaw, said preparation comprising the formation of a bore for receiving an anchor

for a dental implant, said optimal position and said optimal orientation being adapted to

produce a desired position and a desired orientation of the anchor for the implant.

10. The method recited in claim 9, further comprising the step of also operating said computer to generate, on said monitor, a graphic representation of said anchor in said desired

position and said desired orientation relative to said bone and said tooth.

11. The method recited in claim 8 wherein said step of generating electrically encoded data

comprises a first step of generating digitized surface data and a second step of generating digitized X-ray data.

12. The method recited in claim 8, further comprising the steps of instructing said

computer to modify said optimal position and said optimal orientation and operating said

computer to generate, on said monitor, a graphic representation of said tool in the modified position and orientation relative to said pre-existing structure.

13. The method recited in claim 8, further comprising the steps of:

in a practice operation, orienting a dental type instrument in juxtaposition to said

pre-existing structure at approximately said optimal position;

providing, to said computer, electrical feedback as to an actual position and an actual

orientation of said instrument;

operating said computer to provide feedback to an operator regarding an angle

between said optimal orientation and said actual orientation.

14. The method recited in claim 13 wherein said instrument is said tool.

15. The method recited in claim 13 wherein said instrument is a practice instrument having a virtual tip.

16. The method recited in claim 15 wherein said virtual tip is a telescoping member.

17. The method recited in claim 8, further comprising the steps of:

using said tool to modify said pre-existing structure to form the preparation;

providing, to said computer, electrical feedback as to motions of said tool; and modifying said graphic representation in accordance with motions of said tool to show

modifications of said pre-existing structure.

18. The method recited in claim 17, further comprising the step of providing to an

operator of said tool an alert signal regarding deviation between an actual position and

orientation of said tool during said step of using and said optimal position and said optimal

orientation.

19. The method recited in claim 8 wherein said step of further operating said computer

to predetermine an optimal position and an optimal orientation of said tool comprises the step

of at least partially automatically analyzing said pre-existing structure to determine position

and orientation of a desired preparation.

20. The method recited in claim 19 wherein said step of further operating said

computer to predetermine an optimal position and an optimal orientation of said tool

additionally comprises the steps of: at least partially automatically accessing an electronic inventory of digitized prosthetic dental devices corresponding to respective actual dental devices of an actual inventory; and

at least partially automatically comparing said digitized prosthetic dental devices in

different positions and orientations to said pre-existing structure to determine an advantageous

position and orientation of a recommended dental device with respect to said pre-existing

structure.

21. The method recited in claim 20 wherein said actual dental devices include anchors and angle elements for dental implants.

22. The method recited in claim 8 wherein said step of operating said computer to

generate a graphic representation includes the step of operating said computer to generate, on

said monitor, graphic representations of a plurality of views of said pre-existing structure.

23. The method recited in claim 22 wherein at least one of said views is generated by

said computer upon interpolation of said electrically encoded data.

24. The method recited in claim 8 wherein said step of generating electrically encoded

data includes the step of collecting X-ray data as to said pre-existing structure.

25. The method recited in claim 8 wherein said step of generating electrically encoded

data includes the step of gathering contour data.

26. The method recited in claim 8 wherein said step of generating electrically encoded

data includes the step of producing a video signal.

27. The method recited in claim 8 wherein said step of operating said computer to generate a graphic representation includes the step of operating said computer to generate, on

said monitor, graphic representations of a cross-sectional view of said pre-existing structure

28 A method for providing information as to a patient's dental condition, comprising

the steps of

generating first electrically encoded data as to external tooth surfaces in the patient's mouth,

transmitting said data to a computer, generating second electrically encoded data as to internal structures in the patient's mouth,

transmitting said second electrically encoded data to said computer, providing said computer with electrically encoded coordinate reference data to enable

said computer to correlate said first electrically encoded data and said second electrically

encoded data, and

operating said computer to generate, on a monitor connected to said computer, a

composite graphic representation of at least one of said external tooth surfaces together with at

least one of said internal structures

29 The method recited in claim 28 wherein said step of providing said computer with

electrically encoded coordinate reference data comprises the step of attaching an X-ray opaque

reference element to a dental surface in the patient's mouth

30 The method recited in claim 29 wherein said step of attaching includes the step of attaching said reference element to an occlusal surface of a tooth in the patient's mouth.

31. The method recited in claim 30 wherein said reference element is attached to said

occlusal surface via an X-ray transparent connector.

32. The method recited in claim 28 wherein said step of providing said computer with

electrically encoded coordinate reference data comprises the step of laying a saddle-like form

on a gum surface in the patient's mouth, said saddle-like form incorporating an X-ray opaque

reference element.

33. The method recited in claim 28, further comprising the steps of operating said computer to distinguish different dentitious structures of the patient and displaying said

different structures in respective colors or respective textural patterns on said monitor.

34. The method recited in claim 33 wherein said different structures include different

substructures of a tooth.

35. The method recited in claim 28, further comprising the steps of operating said

computer to determine points of contact between teeth of an upper jaw and teeth of a lower

jaw and to further determine stress areas in a bone of one of said upper jaw and said lower jaw.

36. The method recited in claim 35, further comprising the steps of (a) providing said

computer with electrically encoded data as to forces exerted by the teeth of said upper jaw and

the teeth of said lower jaw during a biting action and (b) operating said computer to calculate magnitudes of stress in said stress areas.

37. The method recited in claim 28, further comprising the step of calculating a

selected dimension of an internal dental structure from a plurality of related known dimensions.

38. The method recited in claim 37 wherein said internal dental structure is a root of a

tooth and said selected dimension constitutes a thickness of said root, said known dimensions including a width and a depth of said root.

39. The method recited in claim 28, further comprising the steps of at least partially

automatically determining pocket depths and displaying said pocket depths on said monitor.

40. A method of preparing for a surgical operation, comprising the steps of:

scanning internal structure in a patient;

digitizing said internal structure in response to said step of scanning; displaying an image of said internal structure in response to signals produced during

said step of digitizing;

providing a practice surgical instrument with a virtual operating tip;

moving said surgical instrument outside of the patient in a simulation of actual surgery

on a portion of said internal structure;

automatically monitoring said instrument during said step of moving; and

displaying a representation of at least said operating tip of said instrument in overlap

with said image of said internal structure during said step of moving.

41. The method recited in claims 40, further comprising the step of establishing a

coordinate system reference frame outside of the patient for said internal structure, thereby

enabling coordination of said representation with said image.

42. A method for making a dental diagnosis, comprising the steps of:

generating first electrically encoded data as to external tooth surfaces in a patient's mouth;

transmitting said data to a computer;

generating second electrically encoded data as to internal structures in the patient's mouth;

transmitting said second electrically encoded data to said computer;

operating said computer to generate, on a monitor connected to said computer, a

composite graphic representation of said external tooth surfaces together with said internal

structures;

further operating said computer to identify an anatomical condition of the patient's

dentition based on first electrically encoded data and said second electrically encoded data; and

additionally operating said computer to provide an indication of the determined

anatomical condition.

43. The method recited in claim 42 wherein said step of additionally operating said

computer includes the step of displaying said anatomical condition on said monitor in a

predetermined color different from a color in which said composite graphic representation is

displayed.

44. The method recited in claim 42 wherein said step of further operating said computer includes the step of determining location and textural characteristics of said

anatomical condition.

45. A method for providing a computer with data regarding a dentitious structure of a

patient, comprising the steps of:

piercing gum tissue in the mouth of the patient with a point of an instrument;

moving said instrument so that said point contacts a bone surface underlying said gum

tissue; generating a signal indicative of the position of said point in contact with said bone surface; and feeding said signal to the computer.

46. A method for forming a dentitious preparation, comprising the steps of:

displaying on a monitor a graphic representation in a first color of three-dimensional

structure in a patient's mouth;

also displaying on said monitor, in a second color different from said first color, a

graphic representation of desired preparation of said structure, in combination with the graphic

representation of said structure; using a material removal instrument to remove material from a surface of said

structure; and

additionally displaying on said monitor, in combination with the graphic representation

of said structure, a graphic representation of an actual modification of said structure achieved

during said step of using, said actual modification being shown in a third color different from said first color and said second color.

47. The method recited in claim 46, further comprising the steps of:

calculating a distance between said a first surface defined by said desired preparation and a second surface defined by said actual modification; and

selecting said third color from an electronic color palette, wherein different distances

are coded by respective colors, said third color corresponding to the calculated distance.

48. The method recited in claim 46 wherein said third color is a predetermined color to

indicate a spatial difference between said actual modification and the desired preparation.

49. A method for charting a patient's dentition, comprising the steps of:

digitizing surfaces of at least one tooth in the patient's jaw; placing a point of a dental instrument in contact with one of said surfaces;

generating a first electrical signal encoding the location of said point in contact with

said one of said surfaces;

verbally identifying a characteristic of said tooth at said location;

converting the verbal identification into a second electrical signal; and

producing, partially in response to said first electrical signal and said second electrical signal, a chart of said teeth including an indication of said characteristic at said location.

50. The method recited in claim 49 wherein said characteristic is a diagnostic condition

of said tooth at said location.

51. The method recited in claim 50 wherein said characteristic is decay.

52. The method recited in claim 50 wherein said characteristic is a filling.

53. The method recited in claim 49, further comprising the steps of verbally identifying

said tooth, converting that verbal identification into a third electrical signal, and using said third electrical signal to verify said location.

54. A method for use in forming a preparation in a patient's jaw, comprising the steps

of:

fixing a block of material relative to the patient's jaw so that said block is disposed

outside the patient's mouth;

providing a practice dental type instrument with a virtual operating tip; also providing a material removal tool enslaved to said instrument so that said tool and

said instrument move in tandem with one another;

moving said instrument in a virtual operation as if to form the preparation in the

patient's jaw;

during said step of moving, automatically operating said tool via the enslavement

thereof to said instrument, to form a recess in said block;

providing an actual dental type instrument with an operative material removal tip;

additionally providing a probe enslaved to said actual dental type instrument so that

said probe and said actual dental type instrument move in tandem with one another;

upon formation of said recess, operating said actual dental type instrument to form the

preparation in the patient's jaw; and during said step of operating, moving said probe inside said recess to thereby guide and

limit motion of said actual dental type instrument.