WO2013057577A1

WO2013057577A1 - Mould part for drill guide and manufacturing method

Info

Publication number: WO2013057577A1
Application number: PCT/IB2012/002219
Authority: WO
Inventors: Claudio ALBI; Lorenzo GIBERTI
Original assignee: Digital Srl
Priority date: 2011-10-17
Filing date: 2012-10-12
Publication date: 2013-04-25
Also published as: EP2768422A1; GB201117955D0; GB2495730A

Abstract

A mould part (54, 92) for a mould, the mould being for producing a cast (70, 96) of at least a portion of a dental arch of a patient, the cast (70, 96) comprising a bore (72) in the cast (70, 96), the position of the bore (72) in the cast (70, 96) of the dental arch being substantially the same as a predetermined desired position in the dental arch, the mould part (54, 92) comprising: a base portion; and a protrusion (58) extending from the base portion; wherein the protrusion (58) defines the bore (72) in the cast (70, 96). The predetermined desired position in the dental arch may be a desired position for a dental implant in the dental arch. The protrusion (58) may be a hollow tube.

Description

MOULD PART FOR DRILL GUIDE AND MANUFACTURING METHOD

FIELD OF THE INVENTION

The present invention relates to mould parts for moulds.

BACKGROUND

A person's missing teeth may be replaced by prosthetic teeth.

Typically, a treatment comprises a prosthetic tooth and a dental implant screwed into the jawbone to which the replacement tooth is fixed.

During implantation of a dental implant, a hole is drilled in the patient's jawbone into which the dental implant is inserted.

The drilling of the hole in the patient's jawbone into which the dental implant is inserted is typically guided by a tube within a drill guide.

However, the manufacture of such drill guides tends to be time consuming, expensive and somewhat inaccurate.

Also, many conventional processes for producing drill guides (for example a method used to produce the Materialise 'SurgyGuide') comprise applying an X-ray opaque layer to a radiological guide, which is then inserted into the patient mouth before X-ray images of the patient's teeth are taken.

Many dental surgeries or denta) laboratories have relatively low power X- ray machines, with which it tends to be difficult to capture a good image of the X-ray opaque layer applied to the radiological guide.

Furthermore, these X-ray images tend to be particularly prone to "flashes" and the shape and/or positions of the patient's teeth in the image tend to be difficult to ascertain.

Processing of such X-ray images tends to be relatively expensive and may introduce inaccuracies into the image. Also, many conventional methods of producing drill guides, for example the Materialise 'SurgyGuide', use stereo lithography, otherwise known as rapid prototyping, to manufacture the guide from a digital computer model of the patient's jaw with the intended implants. This approach tends to be inaccurate. Furthermore, stereo lithography is an additive manufacturing process and a drill guide produced in this way has an irregular surface, corresponding to the individual polymer layers.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides a mould part for a mould, the mould being for producing a cast of at least a portion of a dental arch of a patient, the cast comprising a bore in the cast, the position of the bore in the cast of the dental arch being substantially the same as a predetermined desired position in the dental arch, the mould part comprising: a base portion; and a protrusion extending from the base portion; wherein the protrusion defines the bore in the cast.

The predetermined desired position in the dental arch may be a desired position for a dental implant in the dental arch.

The protrusion may be a hollow tube.

The mould part may further comprise a further protrusion extending from the base portion, wherein the further protrusion defines a further bore in the cast, the position of the further bore in the cast being substantially the same as a predetermined desired position for a securing pin in the dental arch, and the securing pin is a pin with which a dental drill guide is secured to the dental arch during a procedure of implanting a dental implant into the dental arch.

In a further aspect, the present invention provides a method of manufacturing a mould part, the mould part being in accordance with the first aspect, the method comprising the steps of: providing a digital model of the dental arch; inserting a digital representation of a dental implant into the digital model such that the position of the digital representation of the dental implant in the digital model is the desired position for the dental implant in the dental arch; and using the digital model and the digital representation of a dental implant inserted therein, producing the mould part such that the position of the protrusion on the base portion is dependent on the position of the digital representation of the dental implant in the digital model.

The step of, using the digital model and the digital representation of a dental implant inserted therein, producing the mould part may comprise, using a CNC milling machine, milling a piece of material into the shape of the mould part. The step of providing a digital mode) of the dental arch may comprise: capturing one or more X-ray images of the dental arch; and producing the digital model using said one or more X-ray images.

The step of providing a digital model of the dental arch may comprise: creating a physical model of the dental arch of the patient; using a laser scanner, capturing one or more laser scan images of the physical model of the dental arch; and producing the digital model using said one or more laser scan images.

The step of providing a digital model of the dental arch further may comprise positioning the physical model with respect to a further base portion, the further base portion being substantially the same shape as the base portion; wherein the step of capturing one or more laser scan images of the dental arch comprises capturing one or more laser scan images of the physical model of the dental arch and the further base portion; and the digital model produced using said one or more laser scan images comprises a digital representation of the further base portion.

The step of providing a digital model of the dental arch may comprise registering the digital model produced from the one or more X-ray images and the digital model produced from the one or more laser scan images.

The step of capturing one or more X-ray images of the dental arch may comprise positioning a reference member with respect to the portion of the denta} arch of the patient, and capturing one or more X-ray images of the portion of the dental arch of the patient and the reference member.

The digital model produced from the one or more X-ray images may comprise a digital representation of the reference member. The step of capturing one or more laser scan images of the dental arch may comprise positioning the reference member with respect to the physical model such that position of the reference member with respect to the physical model is substantially the same as that of the reference model with respect to the denta) arch in the X-ray images. The digital model produced from the one or more X-ray images may comprise a digital representation of the reference member.

The step of registering the digital model produced from the one or more X-ray images and the digital model produced from the one or more laser scan images may comprise registering the reference member in the digital model produced from the one or more X-ray images and the reference member in the digital model produced from one or more laser scan images.

The reference member may be coupled to a U-shaped member;

The step of positioning the reference member with respect to the portion of the dental arch of the patient may comprise positioning the U-shaped member with respect to the portion of the dental arch such that an impression of the dental arch is created in the U-shaped member.

The step of positioning the reference member with respect to the physical model may comprise positioning the U-shaped member such that the physical model complements the impressions made in the U-shaped member by the dental arch.

The reference member may be a single fiduciary marker coupled to the U-shaped member.

The reference member may be positioned centrally on the U-shaped member. The step of creating a physical model of the dental arch of the patient may comprise, using the impression of the dental arch in the U-shaped member, casting the physical model of dental arch.

In a further aspect, the present invention provides a method of producing a dental drill guide, the drill guide comprising a drill guide tube for guiding a drill during a procedure of implanting a dental implant into a portion of a dental arch of a patient, the method comprising: using a mould comprising a mould part, the mould part being in accordance with the first aspect of the invention, producing a cast of at least a portion of the dental arch; and using the cast, producing the dental drill guide; wherein the position of the drill guide tube in the drill guide is dependent on the position of the bore in the cast.

The mould part may produced using a method of any of the above aspects.

In a further aspect, the present invention provides a method of producing a digital model of a portion of a dental arch of a patient, the method comprising: capturing one or more images of the internal structure of the portion of the dental arch of the patient; using the captured one or more images, producing a first digital model of the portion of the dental arch; creating a physical model of the portion of the dental arch of the patient; using the physical model, producing a second digital model of the portion of the dental arch; and combining at least some elements of the first digital model and at least some elements of the second digital model to produce the digital model of a portion of a dental arch of a patient.

The one or more images used to produce the first digital model of the dental arch of the patient may be X-ray images.

The step of, using the physical model, producing a second digital model of the portion of the dental arch may comprise: measuring the physical model using a range sensor; and using the range sensor measurements, producing the second digital model. The range sensor may be a laser scanner. The step of combining may comprise registering the first digital model and the second digital model.

The step of capturing one or more images of the internal structure of the portion of the dental arch may comprise positioning a reference member with respect to the portion of the dental arch of the patient, and capturing one or more images of the reference member and the internal structure of the portion of the dental arch.

The first digital model may comprise a digital representation of the reference member.

The step of, using the physical model, producing a second digital model of the portion of the dental arch may comprise positioning the reference member with respect to the physical model such that position of the reference member with respect to the physical model is substantially the same as that of the reference model with respect to the dental arch in the images of the internal structure, and producing the second digital model such that the second digital model comprises a digital representation of the reference member.

The step of combining may comprise registering the reference member in the first digital model and the reference member in the second digital model.

The reference member may be coupled to a U-shaped member;

The reference member may be a single fiduciary marker coupled to the U-shaped member. The reference member may be positioned centrally on the U-shaped member.

The step of creating a physical model of the dental arch of the patient may comprise, using the impression of the dental arch in the U-shaped member, casting the physical model of the dental arch.

In a further aspect, the present invention provides a method of manufacturing a mould part for a mould, the mould being for producing a cast of at least a portion of a dental arch of a patient, the cast comprising a bore in the cast, the position of the bore in the cast of the dental arch being substantially the same as a predetermined desired position for a dental implant in the dental arch, the mould part comprising a base portion and a protrusion extending from the base portion, wherein the protrusion defines the bore in the cast, the method comprising: producing the digital model of a portion of a dental arch of a patient using a method according to any of the above aspects; inserting a digital representation of the dental implant into the digital model such that the position of the digital representation of the dental implant in the digital model is the desired position for the dental implant in the dental arch; and using the digital model and the digital representation of a dental implant inserted therein, producing the mould part such that the position of the protrusion on the base portion is dependent on the position the digital representation of the dental implant in the digital model.

The step of, using the digital model and the digital representation of a dental implant inserted therein, producing the mould part may comprise, using a CNC drilling machine, milling a piece of material into the shape of the mould part.

In a further aspect, the present invention provides a method of producing a dental drill guide, the dental drill guide comprising a drill guide tube for guiding a drill during a procedure of implanting a dental implant into a dental arch of a patient, the method comprising: manufacturing a mould part using a method according to any of the above aspects; using a mould that comprises the mould part, producing a cast of at least a portion of the dental arch; and using the cast, producing the dental drill guide; wherein the position of the drill guide tube in the drill guide is dependent on the position of the bore in the cast.

In a further aspect, the present invention provides a method of producing a dental drill guide, the dental drill guide comprising a drill guide tube for guiding a drill during a procedure of implanting a dental implant into a dental arch of a patient, the method comprising: producing the digital model of a portion of a dental arch of a patient using a method according to any of the above aspects; inserting a digital representation of the dental implant into the digital model; and using the digital model and the digital representation of a dental implant inserted therein, producing the drill guide, wherein the position and orientation of the drill guide tubes in the drill guide is dependent on the position and orientation of the digital representation of a dental implant in the digital model.

In a further aspect, the present invention provides a digital model of a portion of a dental arch of a patient, the digital model being produced using a method in accordance with any of the above aspects.

In a further aspect, the present invention provides apparatus for use during a dental imaging process, the apparatus comprising: a portion for inserting into the mouth of a patient and for, when the portion is inserted into the mouth of the patient, securely engaging with at least a portion of the dental arch of the patient; and a fiduciary marker, the fiduciary marker being detectable by a first imaging system and a second imaging system; wherein the first imaging system is for capturing images of an internal structure of the dental arch; and the second imaging system is configured to image an outer surface of entities it is used to capture images of.

The apparatus may be a dental fork.

The first imaging system may be an imaging system selected from a group comprising: an X-ray imaging system, an MRI system, and an ultrasound imaging system.

The second imaging system may be an imaging system selected from a group comprising: a laser scanner, a contact 3D scanner, and a CMM machine. The fiduciary marker may be positioned at or proximate to the centre of the portion.

The fiduciary marker may be a 3D barcode.

The portion may be a U-shaped member.

The apparatus may further comprise a handle positioned at the bottom of the U-shaped member.

When the portion is inserted into the mouth of the patient, the portion may securely engage with at least a portion of the dental arch by means of a viscous liquid material applied to a surface of the portion and into which the dental arch is impressed.

The portion may comprise a plurality or holes or indentations in a surface of the portion, the holes or indentations being for facilitating the attachment to the surface of a viscous liquid material.

In a further aspect, the present invention provides a drilling method comprising: using a digital model, the digital model comprising a digital representation of a dental arch of a patient and a digital representation of a dental implant positioned within the digital representation of the dental arch, controlling a drilling machine to drill a bore into a physical model of the dental arch; wherein the bore is drilled such that a position and orientation of the bore in the physical model is dependent upon the position and orientation of the digital representation of the dental implant in the digital representation of a dental arch.

The drilling machine is a CNC drilling machine.

The digital model may further comprise a digital representation of a holding plate.

During drilling, the physical model may be coupled to the holding plate such that the relative position of the physical model and the holding plate is substantially the same as the relative position, in the digital model, of the digital representation of the dental arch and the digital representation of the holding plate. In a further aspect, the present invention provides a method of producing a dental drill guide, the dental drill guide comprising a drill guide tube for guiding a drill during a procedure of implanting a dental implant into a dental arch of a patient, the method comprising: providing a digital model, comprising a digital representation of the dental arch and a digital representation of a dental implant positioned within the digital representation of the dental arch; providing a physical model of the dental arch; performing the drilling method in accordance with the preceding aspect; and using the physical model with the bore drilled therein, producing the dental drill guide; wherein the position of the drill guide tube in the drill guide is dependent on the position of the bore in the physical model.

The step of providing the digital model may comprise: producing a digital model of the dental arch using a method according to any of the above aspects; and inserting a digital representation of the dental implant into the digital model of the dental arch.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic illustration (not to scale) of a dental implant drill guide;

Figure 2 is a schematic illustration (not to scale) showing certain pieces of apparatus used in the below described process of manufacturing the drill guide;

Figure 3 is a process flow chart showing certain steps of an embodiment of a process of manufacturing the drill guide;

Figure 4 is a schematic illustration (not to scale) of a perspective view of a dental fork used in this embodiment.

Figure 5 is a schematic illustration (not to scale) of an exploded view of a first assembly formed during the process of Figure 3;

Figure 6 is a schematic illustration (not to scale) of a side view of certain elements of a digital implant model formed during the process of Figure 3; Figure 7 is a schematic illustration (not to scale) of a digital model of a second base plate formed during the process of Figure 3;

Figure 8 is a schematic illustration (not to scale) of an exploded view of a third assembly formed during the process of Figure 3;

Figure 9 is a schematic illustration (not to scale) of an exploded view of a fourth assembly formed during the process of Figure 3;

Figure 10 is a schematic illustration (not to scale) of a second plaster cast formed during the process of Figure 3;

Figure 11 is a schematic illustration (not to scale) showing the second plaster cast, a plurality of rods, and a plurality of drill guide tubes;

Figure 12 is a schematic illustration (not to scale) of the structure shown in Figure 11 with resin applied to it;

Figure 13 is a process flow chart showing certain steps of an embodiment of a process of producing a further drill guide;

Figure 14 is a schematic illustration (not to scale) of an exploded view of a fifth assembly formed during the process of Figure 13;

Figure 15 is a schematic illustration (not to scale) of a side view of certain elements of a further digital implant model formed during the process of Figure 3;

Figure 6 is a schematic illustration (not to scale) of the digital model of a third base plate formed during the process of Figure 13;

Figure 17 is a schematic illustration (not to scale) of a fourth plaster cast formed during the process of Figure 13; and

Figure 18 is a process flow chart showing certain steps of a further embodiment of a process of producing the drill guide.

DETAILED DESCRIPTION Figure 1 is a schematic illustration (not to scale) of a dental implant drill guide, herein after referred to as the "drill guide" and indicated in Figure 1 by the reference numeral 2.

An embodiment of a process of manufacturing the drill guide is described in more detail later below with reference to Figure 3.

In this embodiment, the drill guide 2 comprises a drill guide body 4.

In this embodiment, the drill guide 2 further comprises four drill guide sockets 6 positioned in the drill guide body 4.

In this embodiment, the drill guide 2 further comprises four drill guide tubes 8. Each drill guide tube is inserted into a respective drill guide socket 6.

In this embodiment, the drill guide 2 is used in a conventional way. In particular, in this embodiment, drill guide 2 is inserted into the mouth of a patient for which the drill guide 2 is produced (as described in more detail later below with reference to Figure 3). Holes in the patient's jawbone are then drilled by the dental surgeon by inserting a drill through each of the drill guide tubes 8 and into the patient's jawbone. Each hole is drilled into the jawbone to a respective predetermined depth. Thus, drill holes are created in the patient's jawbone into which dental implants are then affixed.

In this embodiment, a dental implant is a metal screw to which a prosthetic tooth is attached. The prosthetic tooth may be temporary or permanent, and may be made of any appropriate material (e.g. ceramic, gold, plastic, etc.).

Figure 2 is a schematic illustration (not to scale) showing certain pieces of apparatus used in the below described process of manufacturing the drill guide 2.

In this embodiment, the pieces of apparatus used in the below described process of manufacturing the drill guide 2 are located at three separate (i.e. remote from one another) locations. These locations are the surgery of the dental surgeon (hereinafter referred to as the "dental surgery" and indicated in figure 2 by the reference numeral 12), a dental laboratory 13, and a computer numerical control (CNC) drilling facility 14.

In this embodiment, the dental surgery 12 comprises an X-ray machine 18, and a first computer terminal 20.

In this embodiment, the X-ray machine 18 is a conventional dental X-ray device capable of capturing X-ray images of a patient's jawbones and teeth. The X-ray machine 18 is coupled to the first computer terminal 20 such that, in operation, image data measured by the X-ray machine 8 are sent from the X- ray machine 18 to the first computer terminal 20.

In this embodiment, the first computer terminal 20 is arranged to process image data received from the X-ray machine 18. The processing of the received image data performed by the first computer terminal 20 is described in more detail later below with reference to Figure 3.

In this embodiment, the dental laboratory 13 comprises a laser scanner 16 and a second computer terminal 17.

In this embodiment, the laser scanner 6 is a conventional laser scanner capable of scanning three-dimensional objects. The laser scanner 16 is coupled to the second computer terminal 17 such that, in operation, image data measured by the laser scanner 6 are sent from the laser scanner 6 to the second computer terminal 1 .

In this embodiment, the second computer terminal 17 is arranged to process image data received from the laser scanner 16. The processing of the received image data performed by the second computer terminal 17 is described in more detail later below with reference to Figure 3.

In this embodiment, CNC drilling facility 14 comprises a third computer terminal 22 and a CNC drilling machine 24.

In this embodiment, the CNC drilling machine 24 is a conventional CNC drilling machine 24. The CNC drilling machine 24 is coupled to the third computer terminal 22 such that, in operation, the CNC drilling machine 24 may be controlled using the third computer terminal 22. In this embodiment, the dental surgery 12, the dental laboratory 13, and the CNC drilling facility 14 are coupled together such that, objects may be transported (e.g. by post or courier) between those entities, and such that data (e.g. digital files) may be sent (e.g. via email or the Internet) between those entities.

Figure 3 is a process flow chart showing certain steps of an embodiment of a process of manufacturing the drill guide 2.

In this embodiment, the drill guide 2 is for facilitating the implantation of dental implants into the lower jaw of the patient. Also, in this embodiment, the patient is an adult male human.

In this embodiment, steps s2 to si 4 are performed at the dental surgery 12, step S15 is performed between the dental surgery 12 and the dental laboratory 13, steps s16 to s34 are performed at the dental laboratory 13, step s36 is performed between the dental laboratory 3 and the dental surgery 12, steps s38 and s40 are performed at the dental surgery 12, step s42 is performed between the dental surgery 2 and the CNC drilling facility 14, steps S44 and s46 are performed at the CNC drilling facility 1 , step s48 is performed between the CNC drilling facility 14 and the dental laboratory 13, steps s50 to s68 are performed at the dental laboratory 13, and step s70 is performed between the dental laboratory 13 and the dental surgery 12.

At step s2, a "dental fork", hereinafter referred to as "the fork", is prepared.

Figure 4 is a schematic illustration (not to scale) of a perspective view of the fork 26 used in this embodiment.

In this embodiment, the fork 26 is made of a biocompatible material.

In this embodiment, the fork 2 comprises a U-shaped section. The arms of the U-shaped section of the fork 26 are indicated in figure 4 by the reference numerals 28.

The fork 26 further comprises a handle 30 which protrudes from the bottom of the U-shaped section away from the arms 28. In this embodiment, the fork 26 is of a size such that the U-shaped portion of the fork 26 may be inserted into the patient's mouth. Whilst the U- shaped portion is in the patient's mouth, the handle 30 protrudes from the patient's mouth.

In this embodiment, the arc of the U-shaped portion is substantially the same shape as a dental arch (i.e. the arc formed by a row of teeth) of an average male human (i.e. a generic patient).

In this embodiment, the fork 26 comprises a fiduciary marker 32. In this embodiment, the fiduciary marker 32 is a single component or feature that can be used as a reference in an image, e.g. a single 3D bar code.

In this embodiment, the fiduciary marker 32 is positioned relatively centrally on the fork 26, e.g. the fiduciary marker is positioned at or proximate to the centre of mass of the body of the fork 26.

In this embodiment, the fiduciary marker 32 is detectable by both the laser scanner 16 and the X-ray machine 18. The fiduciary marker 32 is made of a biocompatible and substantially radio-opaque material.

In this embodiment, the fork 26 further comprises a plurality of holes 34. The holes 34 are positioned along the length of the arms 28 of the U-shaped portion of the fork 26. Furthermore, each of the holes 34 is through the entire thickness of an arm 28, i.e. from a top surface of the fork 26 to a bottom surface 26 of the fork 26.

In this embodiment, the length of each of the arms 28 of the fork 26 is 60mm. Also, the length of the handle 30 of the fork 26 is 30mm. Also, the thickness of the fork 26 is 6mm. In other embodiments, the fork 26 may have different dimensions.

In this embodiment, at step s2 the fork 26 is prepared (e.g. by a dental technician or assistant to the dental surgeon or dentist) by applying silicone rubber to the top and bottom surface of the U-shaped portion of the fork 26. The silicone rubber is applied such that silicone rubber is forced through the entire length of each of the holes 34. Thus, the silicone rubber applied to the top surface of the U-shaped portion is in contact (via the holes 34) with the silicone rubber applied to the bottom of the U-shaped portion. This advantageously tends to provide that the coupling of the silicone rubber to the top and bottom surfaces of the U-shaped portion of the fork 26 is relatively secure.

Furthermore, the holes 34 tend to increase the surface area of the top and bottom surfaces of the U-shaped portion to which the silicone rubber is applied. This also advantageously tends to provide that the coupling of the silicone rubber to the top and bottom surfaces of the U-shaped portion of the fork 26 is relatively secure.

At step s4, the prepared fork 26 (i.e. the fork 26 and the silicone rubber applied to the fork 26) is inserted into the patient's mouth.

In this embodiment, the prepared fork 26 is positioned in the patient's mouth such that the silicone rubber applied to the top surface of the fork 26 is in contact with the upper dental arch of the patient (i.e. the patient's teeth, or gum where teeth should be located, on the patient's upper jaw).

Also, in this embodiment, the prepared fork 26 is positioned in the patient's mouth such that the silicone rubber applied to the bottom surface of the fork 26 is in contact with the lower dental arch of the patient (i.e. the patient's teeth, or gum where teeth should be located, on the patient's lower jaw).

At step s6, the patient bites down on the prepared fork 26, thereby creating an impression of the dental arch of the patient in the silicone rubber.

In particular, an impression of the upper dental arch of the patient is created in the silicone rubber that has been applied to the top surface of the fork 26.

Also, an impression of the lower dental arch of the patient is created in the silicone rubber that has been applied to the bottom surface of the fork 26.

At step s8, whilst the fork 26 is still in the patient's mouth and the patient is still biting down on the fork 26, one or more X-ray images of the patient's mouth are taken using the X-ray machine 18. In this embodiment, a conventional cone-beam reconstruction process is used to capture the images of the patient's mouth.

In this embodiment, the X-ray images taken at step s8 capture the patient's teeth, the patient's jawbones, and the fork 26 (including the fiduciary marker 32 of the fork 26). The relative positions of these entities are also captured in the X-ray images.

In this embodiment, the one or more X-ray images of the patient's mouth are sufficient to allow for a 3-dimensional digital model of the patient's teeth, the patient's jawbones, and the fork 26 to be created.

In this embodiment, the resolution of each X-ray image is 512 x 512 pixels for each image.

At step s10, the captured X-ray images (or data corresponding to the X- ray images) are sent from the X-ray machine 18 to the first computer terminal 20.

In this embodiment, the Digital Imaging and Communications in Medicine

(DICOM) format is adopted for the handling, storing, printing, and transmitting of the X-ray images.

At step s12, the first computer terminal 20 processes the received X-ray images to create a first 3-dimensional digital model. The first digital model comprises digital representations of the patient's teeth, the patient's jawbones, and the fork 26.

At step s14, the fork 26 with attached the silicone rubber is removed from the patient's mouth.

At step s15, the fork 26 is sent from the dental surgery 12 to the dental laboratory 13.

At step s16, from the impression of the patient's lower dental arch in the silicone rubber attached to the bottom surface of the U-shaped portion of the fork 26, a plaster cast of the patient's lower dental arch, hereinafter referred to as the "first plaster cast", is created at the dental laboratory 13. The first plaster cast is a 3-dimensional plaster model of the patient's lower dental arch.

At step s18, a base plate (hereinafter referred to as the "first base plate"), the first plaster cast, and the fork 26 (with the indented silicone rubber) are coupled together to form a first assembly.

Figure 5 is a schematic illustration (not to scale) of an exploded view of the first assembly 36 formed at step s18 of the process of Figure 3.

In this embodiment, the first assembly 36 comprises the first base plate 38, the first plaster cast 40, and the fork 26. The indented silicone rubber 42 is attached to the fork 26.

In this embodiment, the first base plate 38 is a conventional plastic or resin base plate. In this embodiment, the shape of the first base plate 38 is that of a tube having one end of the tube sealed. In this embodiment, the internal diameter of the tube portion of the first base plate 38 is such that the first plaster cast 40 fits snuggly inside the tube portion of the first base plate 38.

In this embodiment, the first plaster cast 40 is positioned on a top surface of the first base plate 38, i.e. on the sealed end of the first base plate 38 such that the first plaster cast 40 is at least partly inside the tube portion of the first base plate 38. This is done such that a top surface of the first plaster cast 40 (i.e. the surface of the first plaster cast 40 that is the shape of the patient's lower dental arch) is not in contact with the first base plate 38. Also, this is done such that a bottom surface of the first plaster cast 40 (i.e. the surface of the first plaster cast 40 that is opposite to the top surface of the first plaster cast 40) is in contact with the first base plate 38.

The first plaster cast 40 is positioned such that the first plaster cast does not slide about on the top surface of the first base plate 38, i.e. the relative positions of the first plaster cast 40 and the first base plate 38 are substantially fixed.

In this embodiment, the fork 26 (and attached silicone rubber 42) is positioned on to the top of the first plaster cast 40. This is done such that the silicone rubber 42 attached to the bottom surface of the fork 26, into which an indentation of the patient's lower dental arch has been formed, is in contact with the top surface of the first plaster cast 40 (i.e. the surface of the first plaster cast 40 that is the shape of the patient's lower dental arch). Furthermore, this is done such that the (negative) indentations in the silicone rubber 42 mate with the (positive) corresponding protrusions of the patient's lower dental arch on the first plaster cast 40.

The above described relative placement of the first base plate 38, the first plaster cast 40, and the fork 26 is indicated in Figure 5 by dotted lines.

At step s20, the first assembly 36 is scanned using the laser scanner 16.

In this embodiment, data produced by the scanning of the first assembly 36 by the laser scanner 16 are sufficient to allow for a 3-dimensional digital model of the first assembly 36 to be created.

At step s22, data from the laser scanner 16 corresponding to the scanned first assembly 36 are transferred from the laser scanner 16 to the second computer terminal 17.

At step s24, the second computer terminal 17 processes the received laser scanner data to create a second 3-dimensional digital model. The second digital model comprises digital representations of the fork 26, the first plaster cast 40, and the first base plate 38.

At step s26, the first base plate 38 and the first plaster cast 40 are coupled together to form a second assembly.

In this embodiment, in the second assembly, the first plaster cast 40 is positioned on a top surface of the first base plate 38 in the same way as in the first assembly 36, i.e. the second assembly is the same as the first assembly with the fork removed.

At step s28, the second assembly is scanned using the laser scanner 16.

At step s30, data from the laser scanner 16 corresponding to the scanned second assembly 36 are transferred from the laser scanner 16 to the second computer terminal 17. At step s32, the second computer terminal 17 processes the received laser scanner data to create a third 3-dimensional digital model. The third digital model comprises digital representations of the first plaster cast 40, and the first base plate 38.

At step s34, the second digital model (created at step s24) and the third digital model (generated at step s32) are registered by the second computer terminal 17. In this embodiment, this registration process comprises aligning the digital models using surfaces common to both second and third digital models.

The registered second and third digital models are hereinafter referred to as the "first registered model". The first registered model comprises laser scanned images of the first base plate 38, first plaster cast 40, and the fork 26 (with the fiduciary marker 32).

At step s36, the first registered model is sent from the second computer terminal 17 (at the dental laboratory 3) to the first computer terminal 20 (at the dental surgeon 12).

In this embodiment, the first registered model is sent between the computer terminals 7, 20 over the Internet.

At step s38, the first digital model (generated at step s12) and the first registered model (generated at step s34) are registered using the first computer terminal 20 (e.g. by the dental surgeon or an assistant to the dental surgeon).

In other words, at step s38 the first digital model and the first registered model are transformed into a common coordinate system.

In this embodiment, this image registration is performed by transforming one or more of the models such that the position and orientation of the fiduciary marker 32 in each of the digital models is substantially the same.

Thus, a 3-dimensional digital model comprising digital representations of the patient's teeth, the patient's jawbones, the fork 26, the first plaster cast 40 and the first base plate 38 is produced. This 3-dimensional digital model is hereinafter referred to as the "second registered model". The image of the fork 26 within the second registered model may be removed from the second registered model.

At step s40, digital representations of the dental implants (hereinafter referred to as digital implants) are positioned in the second registered model using the first computer terminal 20 (e.g. by the dental surgeon).

Thus, at step s40 a 3-dimensiona! digital model comprising digital representations of the patient's teeth, the patient's jawbones, the fork 26 (optionally), the first plaster cast 40, the first base plate 38, and the digital implants is produced. This digital model is hereinafter referred to as the "digital implant model".

Any appropriate software package may be used to manipulate digital models and e.g. perform step s40. For example, the "Geomagic", or "MIMICS" software packages may be used.

Figure 6 is a schematic illustration (not to scale) of a side view of certain elements of the digital implant model 44. For purposes of clarity, digital representations of the fork 26 and the patient's jawbone is not shown in Figure 6. This side view of the digital implant model 44 is a side view of the digital model as may be viewed e.g. on a computer display of the first computer terminal 20.

For convenience and ease of understanding, in Figure 6 the digital representation of the first base plate is indicated with the reference numeral corresponding to the first base plate (i.e. the reference numeral 38). Also, in Figure 6 the digital representation of the first plaster cast is indicated with the reference numeral corresponding to the first plaster cast (i.e. the reference numeral 40).

In this embodiment, digital representations of prosthetic/artificial (replacement) teeth, each of which is hereinafter referred to as a "digital replacement tooth" and indicated in Figure 6 by the reference numeral 48, have been inserted/positioned into the registered model. Digital representations of dental implants, each of which is hereinafter referred to as a "digital implant" and indicated in Figure 6 by the reference numeral 50, have been inserted/positioned into the registered model. Furthermore, each digital implant 50 is attached to a respective digital replacement tooth 48.

In this embodiment, at step s40, using the first computer terminal 20 the digital implants 50 are positioned such that the digital replacement teeth 48 are in a desired position (i.e. where the patient is missing teeth). Furthermore, the lengths, positions, and orientations of the digital implants 50 may be altered so as to, for example, avoid nerves or weak portions of bone in the patient's jawbone whilst at the same time ensuring that the support structure for the replacement tooth provides adequate support.

An axis for each of the digital implants 50 is shown in Figure 6 as a dotted line and indicated by the reference numeral 52.

At step s42, the digital implant model 44 is sent from the first computer terminal 20 (at the dental surgery 12) to the third computer terminal 22 (at the CNC drilling facility 14).

In this embodiment, the digital implant model 44 is sent between the computer terminals 20 and 22, over the Internet.

At step s44, the digital implant model 44 is processed by the third computer terminal 22 to produce a digital model of a second base plate.

Figure 7 is a schematic illustration (not to scale) of the digital model of the second base plate 54.

In this embodiment, the digital model of the second base plate 54 comprises a digital representation of a plate which is the same shape as the first base plate (which, for convenience and ease of understanding is indicated in Figure 7 by the reference numeral corresponding to the first base plate, i.e. reference numeral 38) and four tubular portions 58.

Also shown in Figure 7 are the axes 52. In this embodiment, each of the tubular portions 58 is connected to and extends away from the top surface of the first base plate-shaped portion of the second base plate 54.

Furthermore, in this embodiment the each of the four tubular portions 58 extends away from the first base plate-shaped portion of the second base plate 54 such that the an axis of each of tubular portions 58 is coincident, at least in part, with a different one of the axes 52. In other words, each tubular portion axis points along a different axis 52.

Furthermore, in this embodiment, each of the tubular portions 58 is of a length such that, were the digital representation of the first plaster cast 40 to be positioned on the top surface of the second base plate 54 (as in the digital implant model 44), each of the tubular portions 58 would extend substantially up to, but not extend beyond, the top surface of the digital representation of the first plaster cast 40.

Furthermore, in this embodiment the internal diameter of each of the tubular portions 58 is substantially equal to the external diameter of a digital implant 50.

In this embodiment, the size and shape of the second base plate 54 is substantially the same as that of the first base plate 38 with the four tubular portions 58 attached thereto.

At step s46, the third computer terminal 22 is used to control the CNC drilling machine 24, such that the CNC drilling machine 24 produces the second base plate 54.

In this embodiment, the second base plate 54 is produced by the CNC drilling machine 24 milling, or drilling, an appropriately shaped piece of plastic or resin into the shape of the second base plate 54, as specified by the digital model of the second base plate 54.

At step s48, the second base plate 54, produced at step s34, is sent (e.g. via post or courier) from CNC drilling facility 14 to the dental laboratory 13. At step s50, at the dental laboratory, a collar, the first base plate 38, and the first plaster cast 40 are coupled together to form a third assembly.

Figure 8 is a schematic illustration (not to scale) of an exploded view of the third assembly 60 formed at step s50 of the process of Figure 3.

In this embodiment, the third assembly 60 comprises the collar 62, the first base plate 38 and the first plaster cast 40.

In this embodiment, the collar 62 is a substantially tube-shaped plate. The external diameter of the collar 62 is substantially equal to the external diameter of the tubular portion of the first base plate 38. Furthermore, the internal diameter of the collar 62 is substantially equal to the internal diameter of the tubular portion of the first base plate 38.

In this embodiment, the first base plate 38 and the first plaster cast 40 are coupled together as described above for the first assembly 36 (and second assembly) with reference to step s18 and Figure 5, i.e. the first plaster cast 40 is positioned on the top surface of the first base plate 38 such that the first plaster cast does not slide about on the top surface of the first base plate 38.

In this embodiment, the collar 62 is coupled to the first base plate 38 such that the side of the collar 62 is contiguous with the side of the tubular portion of the first base plate 38. Thus, the collar is placed over the first plaster cast 40.

In this embodiment, the length of the collar 62 is such that, when the collar 62, the first base plate 38 and the first plaster cast 40 are coupled together as described above to form the third assembly 60, the top surface of the first plaster cast 40 does not extend (in a direction away from the first base plate 38) further than the free end of the collar 62.

At step s52, a silicone rubber cast of a negative impression of the first plaster cast 40, hereinafter referred to as the "silicone rubber negative", is created. In this embodiment, this is performed by filling the third assembly 60 with liquid silicone rubber and allowing the silicone rubber to solidify. The solidified silicone rubber is then removed from the third assembly 60.

In particular, in this embodiment, liquid silicone rubber is poured into the free end of the collar 62 of the third assembly 60 (i.e. the end of the collar 62 not coupled to the first base portion 38), and onto the first plaster cast 40. This is done until the first plaster cast 40 is completely submersed in liquid silicone rubber. The silicone rubber is then allowed to solidify and is removed from the third assembly 60.

At step s54, the collar 62, the silicone rubber negative (produced at step s52), and second base plate 54 (produced at step s34 and sent to the dental laboratory 13 at step s48) are coupled together to form a fourth assembly.

Figure 9 is a schematic illustration (not to scale) of an exploded view of the fourth assembly 64 formed at step s54 of the process of Figure 3.

In this embodiment, the fourth assembly 64 comprises the collar 62, the silicone rubber negative 66 and the second base plate 54. In this embodiment, the collar 62 the silicone rubber negative 66 are coupled together such that the relative position between the collar 62 and the silicone rubber negative 66 in the fourth assembly 64 is substantially the same as the relative position between the collar 62 and the silicone rubber negative 66 when the silicone rubber negative 66 is formed at step s40.

In this embodiment, the collar 62 is coupled to the second base plate 54 such that the side of the collar 62 is contiguous with the side of the tubular portion of the second base plate 54.

Furthermore, in this embodiment the collar 62 is coupled to the second base plate 54 such that, in the fourth assembly 64, the orientation relative to the collar 62 of the portion of the second base plate 54 that is the same shape as the first base plate 38 is substantially the same as the orientation relative to the collar 62 of the first base plate 38 in the third assembly 60. Equivalent^, the fourth assembly 64 may be formed as follows. After the silicon rubber has hardened at step s52, the first base plate 38 and the first plaster cast 40 are removed from the third assembly 60. The relative position between the collar 62 and the silicone rubber negative 66 is maintained. The second base plate 54 is then coupled to the collar 62 such that the portion of the second base plate 54 which is the same shape as the first base plate 38 is in substantially the same position, relative to the collar 62, as the first base plate 38 was before being removed from the third assembly 60.

In this embodiment, the fourth assembly 64 comprises a cavity between the second base plate 54 and the silicone rubber negative 66. This cavity is hereinafter referred to as "the cavity".

At step s56, a second plaster cast is formed by filling the cavity in the fourth assembly 64 with liquid plaster, allowing this liquid plaster to solidify.

In this embodiment, the cavity may be filled with plaster through a hole in the second base plate 54 (this hole is not shown in the Figures). Figure 10 is a schematic illustration (not to scale) of the second plaster cast 70 formed at step s56. For convenience and ease of understanding, the second plaster cast 70 is shown in Figure 10 on its own. However, in reality, in this embodiment the second plaster cast 70 is coupled to the second base plate 54.

In this embodiment, the shape of the second plaster cast 70 is substantially the same as that of the first plaster cast 40 with four cylindrical bores 72 therein.

In this embodiment, the tubular portions 58 of the second base plate 54 define the bores 72 in the second plaster cast 70. In other words, the tubular portions 58 are protrusions from the base of the second base plate 54 that define bores 72 in the second plaster cast 70 (when the second base plate 54 is used to cast the second plaster cast 70). In this embodiment, the second base plate 54 is a mould part for casting the second plaster cast 70. In this embodiment, the size and the position (i.e. the orientations) of each of the bores 72 in the second plaster cast 70 is substantially the same as the size and the position of a respective digital implant 50 in the digital representation of the first plaster cast 40 (in the digital implant model 44).

Thus, the second plaster cast 70 is a positive cast of the patient's lower dental arch (as is the first plaster cast 40), which comprises bores 72. A tubular portion 58 of the second base plate 54 is in each bore 72. Each of the tubular portions 58 is suitable for receiving a dental implant 50 that fixes a respective prosthetic tooth 48 into the mouth of the patient (i.e. as the internal diameter of a tubular portion 58 is substantially equal to the external diameter of a dental implant)..

At step s58, a metal rod is placed into each of the tubular portions 58.

In this embodiment, each metal rod is of a diameter that is substantially equal to the internal diameter of the tubular portion 58 into which it is inserted.

In this embodiment, each metal rod is inserted into a respective tubular portion 58 such that the metal rod extends away from the top surface of the second plaster cast 70.

Furthermore, in this embodiment, each metal rod is inserted into a respective bore such that the axis of the rod is substantially coincident with the axis of the cylindrical bore 72 (i.e. the axis 52 of the tubular portion 58) into which it is inserted.

Thus, after step s58, each of the tubular portions 58 has placed within it a respective rod. Each rod has a non-free end that is positioned within a tubular portion 58of the second base plate 54, and a free end, opposite to the non-free end, that is distal from the second plaster cast 70

At step s60, along each of the respective rods, a respective drill guide tube 8 (which is, in effect, a metal tube, of which further details are provided above with reference to Figure 1) is slid down, from the free end of that rod towards the non-free end of that rod, until the respective drill guide tube 8 contacts the second plaster cast 70. Figure 1 1 is a schematic illustration (not to scale) showing the second plaster cast 70, the rods 74, and the drill guide tubes 8. For convenience and ease of understanding, the second base plate 54 is not shown in Figure 1 .

In this embodiment, a drill guide tube 8 is placed on each of the rods 74 such that one end of the drill guide tube 8 is in contact with the second plaster cast 70.

In this embodiment, each of the drill guide tube 8 fits snugly around the rod 74 along which that drill guide tube 8 is positioned. In particular, the internal diameter of a drill guide tube 8 is substantially equal to the external diameter of the rod 74 along which that drill guide tube 8 is positioned.

At step s62, relatively soft resin is applied to the surface of the second plaster cast 70 that corresponds to the lower dental arch of the patient.

For example, at the dental laboratory 13, soft resin is pushed onto the second plaster cast 70 such that the surface of the second plaster cast 70 that corresponds to the lower dental arch of the patient is completely covered by the soft resin.

In this embodiment, the soft resin is applied such that the external sides of each of the drill guide tubes 8 is substantially covered by resin, but such that the ends of the drill guide tubes 8 are not covered by resin.

Figure 2 is a schematic illustration (not to scale) of the structure formed at step s62 (i.e. the second plaster cast 70, the rods 74, and the drill guide tubes 8) after the resin 78 has been applied at step s62.

At step s64, the resin 78 applied at step s50 is allowed to harden.

At step s66, the rods 74 are removed from the tubular portions 58 and from the drill guide tubes 8.

In this embodiment, each of the rods 74 is removed by pulling that rod 74, from its free end, in a direction that points substantially along the axis of that rod 74 and away from the second plaster cast 70, until it is completely removed from the second plaster cast 70, the second base plate 54 and the respective drill guide tube 8. In other words, each of the rods 74 is removed by pulling that rod 74 such that its non-free end is pulled out of the respective bore 72 and through the respective drill guide tube 8 until the non-free end of the rod 74 becomes free.

At step s68, the resin 78, into which the drill guide tube 8 are set, is removed from the second plaster cast 70.

The resin 78 and the drill guide tube 8 are the drill guide 2 shown in Figure 1 as described in more detail above. In this embodiment, the solidified resin 78 forms the drill guide body 4 into which the drill guide tube 8 are set.

Thus, the drill guide 2 is formed.

At step s70, the drill guide is sent from the dental laboratory 13 to the dental surgery 12 (for use by the dentist).

Thus, a drill guide, and a method for producing said drill guide, is provided.

An advantage provided by the above described method for producing a drill guide is that the axes of the drill guide tubes of the drill guide substantially align with the desired axes of the dental implants, when the drill guide is placed in the patient's mouth (i.e. during surgery). This tends to facilitate the accurate placement of dental implants in the jawbone of a patient, for example, such that nerves of the patient and areas of weak bone are avoided. This tends to provide that the dental implants are relatively securely fixed in the jawbone of the patient.

The positioning of the dental implants relative to the patient's jaw using software, i.e. the placement of digital dental implants into a digital model of the patient's mouth (as performed at step s40) advantageously provides that the position of the dental implants in the patient's mouth may be altered/adjusted as desired so to ensure the replacement teeth are in an appropriate place, and the implant is secure. This may be performed without the patient present and without the patient suffering discomfort.

In many conventional processes for producing drill guides, a radiological guide is produced. This conventional radiological guide comprises a negative impression of the patient's existing teeth and a negative impression of a dental implant to be inserted. The surface of the conventional radiological guide that comprises the negative impression of a dental implant is coated with a X-ray opaque layer, such that when the conventional radiological guide is inserted into the patient's mouth and the patient's mouth is X-rayed, the positions of the dental implants are present in the X-ray images (due to the X-ray opaque layer). However, many dental surgeries or dental laboratories have relatively low power X-ray machines. Using such machines it tends to be difficult to capture a good image of the teeth and/or the X-ray opaque layer applied to the conventional radiological guide. Furthermore, these X-ray images tend to be particularly prone to "flashes", which means that the shape and/or positions of the patient's teeth in the image tend to be difficult to ascertain. Thus, conventionally there tends to be a requirement to filter x-ray images of the patient's teeth and jaw. This filtering tends to be relatively expensive and may introduce inaccuracies into the image. The above described method advantageously tends to solve this problem by avoiding the use of an X-ray opaque coating on radiological guide, or other structure, placed in the patient's mouth during X-ray.

The combination of the use of X-ray and laser scanner images advantageously tends to provide that the images of the patient's teeth in the registered model are of relatively high quality. Thus, it tends to be possible to avoid expensive image filtering processes.

It tends to be advantageously possible to use the digital model that comprises the X-ray images and the digital implants, in combination with photographs/scans of the patient's head or face to produce images of the patient after the implants have been inserted (i.e. post-operative impressions of the patient). This may be implemented, for example, using visualisation software e.g. facial mapping tools. The post-operative impressions of the patient may be used to check that implants would for properly in the patient's mouth and are properly supported by the patient's jaw (i.e. that the implants are the correct size and shape for the particular patient). The post-operative impressions may also be used to reassure the patient. The use of a single fiduciary marker positioned centrally on the fork tends to facilitate the process of registering the images from the different image sources (e.g. as performed at step s38). Different types of structures may be used instead of the fiduciary marker to perform registration of the images from the different image sources, for example three or more tungsten plugs positioned at different points on the fork may be used. However, having such structures at different positions on the fork may mean that capturing images that contain all of the reference structures, and all the patient's teeth, is difficult. Having a single fiduciary marker positioned relatively centrally on the fork tends to alleviate this problem.

Many conventional methods of drill guide production use stereo lithography (otherwise known as rapid prototyping), under computer control from a digital model, to reproduce the shape of the drill guide and the position of the guide inserts. This introduces errors associated with X-ray imaging of the patient's jaw, the production of the digital model and inaccuracy inherent in the rapid prototyping process. In the subject method described here, the production of the drill guide by a process of direct moulding from a physical impression taken from the patient's mouth is more accurate and, compared to the layered surface of a drill guide produced by stereo lithography, the guide has a smoother finish and tends to provide a better fit in the patient's mouth, thus reducing the need for final adjustments by the dentist. Furthermore, using high precision CNC machining to reproduce the alignment of the drill inserts tends to be inherently more accurate than a rapid prototype based method. As well as being more accurate, by avoiding the use of stereo lithography, the new technique is cheaper and faster.

The moulding of the drill guide 2 into the shape of the patient's dental arch (by forming the resin 78, which forms the drill guide body 4, around the second plaster cast 70) tends to provide that movement of the drill guide in the patient's mouth during surgery is opposed. This is because the drill guide body 4 is moulded into the shape of the patient's remaining teeth, which tend to provide a relatively immovable structure against which to fit the dental guide 2. Optionally, the above described drill guide 2 may be such that the drill guide comprises one or more additional holes thorough the drill guide body 4. During use of the drill guide 2, the drill guide 2 may be secured to the patient's jawbone by inserting a securing pin, or screw, through each of these holes and into the patient's jawbone. This tends oppose the movement of the drill guide inside the patient's mouth during surgery. The position and orientation of these holes for guiding the one or more securing pins may be determined in the same way as that described above for the dental implants.

It tends to be difficult to securely fix a dental guide in the mouth of a patient with few (or no) remaining teeth. This is because there are few (or no) teeth to provide a relatively immovable structure against which to fit the dental guide. The gums of patients tend to be relatively soft, and if a dental guide is fixed against the patient's gum, it tends to be prone to moving about.

What will now be described is an embodiment of a method of producing a drill guide for use with a patient with few, or no remaining teeth. This drill guide will hereinafter be referred to as the "further drill guide".

In the below described embodiment, the patient has three remaining teeth. During the process of producing a further drill guide, these remaining teeth are removed. Thus, the further drill guide, and the process of producing the further drill guide are particularly useful in situations where the patient is to undergo implantation of a complete dental arch.

The below described further drill guide advantageously tends to address the aforementioned problem of drill guides moving during surgery due to the lack of teeth against which to secure them.

Figure 13 is a process flow chart showing certain steps of an embodiment of a process of producing the further drill guide.

In this embodiment, the further drill guide is for facilitating the implantation of dental implants into the lower jaw of the patient with few (or no) remaining teeth. Also, in this embodiment, the patient is an adult male human. In this embodiment, steps s80 to s86 are performed at the dental surgery

12, step s88 is performed between the dental surgery 12 and the dental laboratory 13, steps s90 to s1 12 are performed at the dental laboratory 13, steps s1 14 and s1 16 are performed between the dental laboratory 13 and the dental surgery 12, steps s1 8 to s132 are performed at the dental surgery 2, step s134 is performed between the dental surgery 2 and the CNC drilling facility 14, steps s136 and s 38 are performed at the CNC drilling facility 14, step s 0 is performed between the CNC drilling facility 14 and the dental laboratory 13, steps s142 to s150 are performed at the dental laboratory 13, step s151 is performed between the dental surgery 12 and the dental laboratory

13, steps s152 to s162 are performed at the dental laboratory 3, steps s164 is performed between the dental laboratory 3 and the dental surgery 2, steps s 66 to s174 are performed at the dental surgery 12, steps s176 to s192 are performed at the dental laboratory 13, and step s196 is performed between the dental laboratory 13 and the dental surgery 12.

At step s80, the fork 26 is prepared as described above with reference to step s2 of Figure 3, and with reference to Figure 4.

At step s82, the prepared fork 26 is inserted into the patient's mouth, as described above with reference to step s4 of Figure 3. At step s84, the patient bites down on the prepared fork 26, thereby creating an impression of the dental arch of the patient in the silicone rubber, as described above with reference to step s6 of Figure 3.

At step s86, the fork 26 with attached the silicone rubber is removed from the patient's mouth, as described above with reference to step s 4 of Figure 3. At step s88, the fork is sent from the dental surgery 12 to the dental laboratory 13.

At step s90, from the impression of the patient's lower dental arch in the silicone rubber attached to the bottom surface of the U-shaped portion of the fork 26, a plaster cast of the patient's lower dental arch, hereinafter referred to as the "third plaster cast", is created. In this embodiment, this step (step s90) is performed in the same way as that of creating the first plaster cast 40, as described above with reference to step s16 of Figure 3.

At step s92, relatively soft resin is applied to the surface of the third plaster cast that corresponds to the lower dental arch of the patient.

For example, soft resin is pushed onto the third plaster cast such that the surface of the third plaster cast that corresponds to the lower dental arch of the patient is completely covered by the soft resin.

At step s94, the resin applied to the third plaster cast at step s70 is allowed to harden. This solidified resin is hereinafter referred to as the "radiological guide".

At step s96, the first base plate 38, the third plaster cast, the radiological guide, and the fork 26 (with the indented silicone rubber removed) are coupled together to form a fifth assembly.

Figure 14 is a schematic illustration (not to scale) of an exploded view of the fifth assembly 80 formed at step s74 of the process of Figure 13.

In this embodiment, the fifth assembly 80 comprises the first base plate 38, the third plaster cast 82, the radiological guide 84, and the fork 26. The indented silicone rubber has been removed from the fork 26.

In this embodiment, the third plaster cast 82 is positioned on the top surface of the first base plate 38 in the same way that the first plaster cast 40 is positioned on the top surface of the first base plate 38 at step s18 of Figure 3 (as described in more detail above with reference to Figure 5).

In this embodiment, the radiological guide 84 is positioned onto the top surface of the third plaster cast 82 (i.e. the surface of the third plaster cast 82 that is a positive model of the lower dental arch of the patient). Furthermore, this is done such that the (negative) indentations in the radiological guide 84 mate with the (positive) corresponding protrusions of the patient's lower dental arch on the third plaster cast 82. In this embodiment, the fork 26 is positioned on to the top of the radiological guide 84. In this embodiment, this is done such that the position of the fork 26 relative to the radiological guide 84 is substantially fixed.

The above described relative placement of the first base plate 38, the third plaster cast 82, the radiological guide 84, and the fork 26 is indicated in Figure 1 by dotted lines.

At step s98, the fifth assembly 80 is scanned using the laser scanner 16.

In this embodiment, this is done as described above for the first assembly 36 at step s20 of Figure 3.

At step s100, data from the laser scanner 16 corresponding to the scanned fifth assembly 80 are transferred from the laser scanner 16 to the second computer terminal 17.

In this embodiment, this is done as described above for the first assembly 36 at step s22 of Figure 3.

At step s102, the second computer terminal 7 processes the received laser scanner data to create a 3-dimensional digital model, which is hereinafter referred to as the "fourth digital model". The fourth digital model comprises digital representations of the first base plate 38, the third plaster cast 82, the radiological guide 84, and the fork 26.

In this embodiment, this is done as described above for the second digital model at step s24 of Figure 3.

At step s104, the first base plate 38, the third plaster cast 82, and the radiological guide 84 are coupled together to form a sixth assembly.

In this embodiment, in the sixth assembly is the same as the fifth assembly with the fork 26 removed.

At step s106, the sixth assembly is scanned using the laser scanner 16.

At step s108, data from the laser scanner 16 corresponding to the scanned sixth assembly 36 are transferred from the laser scanner 16 to the second computer terminal 1 . At step s110, the second computer terminal 17 processes the received laser scanner data to create a fifth 3-dimensional digital model. The fifth digital model comprises digital representations of the first base plate 38, the third plaster cast 82, and the radiological guide 84.

At step si 12, the fourth digital model (created at step s102) and the fifth digital model (generated at step s110) are registered by the second computer terminal 17. In this embodiment, this registration process comprises aligning the digital models using surfaces common to both fourth and fifth digital models.

The registered fourth and fifth digital models are hereinafter referred to as the "third registered model". The third registered model comprises laser scanned images of the first base plate 38, the third plaster cast 82, the radiological guide 84, and the fork 26 (with the fiduciary marker 32).

At step s114, the third registered model is sent from the second computer terminal 17 (at the dental laboratory 13) to the first computer terminal 20 (at the dental surgeon 12).

In this embodiment, the first registered model is sent between the computer terminals 17, 20 via email or over the Internet.

At step s116, the fork 26 and the radiological guide 84 are sent from the dental laboratory 13 to the dental surgery 12.

At step s118, the radiological guide 84 and the fork 26 are placed in the patient's mouth.

In this embodiment, this is done such that the relative position of the fork 26 and the radiological guide 84 inside the patient's mouth is substantially the same as the relative position of the fork 26 and the radiological guide 84 in the fifth assembly 80.

Furthermore, in this embodiment the radiological guide 84 and the fork 26 are placed in the patient's mouth such that the (negative) indentations in the radiological guide 84 mate with the (positive) corresponding protrusions (i.e. the remaining teeth) of the patient's lower dental arch. At step s120, with the fork 26 and the radiological guide 84 inside the patient's mouth, one or more X-ray images of the patient's mouth are taken using the X-ray machine 18.

In this embodiment, this is done as described above at step s8 of Figure 3.

At step s122, the captured X-ray images (or data corresponding to the X- ray images) are sent from the X-ray machine 18 to the first computer terminal 20.

In this embodiment, this is done as described above at step S10 of Figure 3.

At step si 24, the first computer terminal 20 processes the received X-ray images to create a 3-dimensional digital model, which is hereinafter referred to as the "sixth digital model". The sixth digital model comprises digital representations of the patient's teeth, the patient's jawbones, the radiological guide 84 and the fork 26.

In this embodiment, this is done as described above at step s12 of Figure

3.

At step s1 6, the fork 26 and the radiological guide 84 are removed from the patient's mouth.

At step s128, the third registered model (generated at step s1 2) and the sixth digital model (generated at step s124) are registered using the first computer terminal 20 (e.g. by the dental surgeon or an assistant to the dental surgeon).

In this embodiment, this is done as described above at step s38 of Figure 3.

Thus, a 3-dimensional digital model comprising digital representations of the patient's teeth, the patient's jawbones, the radiological guide 84, the fork 26, the third plaster cast 82 and the first base plate 38 is produced. This 3- dimensional digital model is hereinafter referred to as the "fourth registered model". At step s130, digital representations of the dental implants (i.e. the digital implants 50) and digital representation of the prosthetic teeth 48 are positioned in the fourth registered model using the first computer terminal 20 (e.g. by the dental surgeon).

In this embodiment, this is done as described above at step s40 of Figure

3.

At step s132, digital representations of three securing pins (hereinafter referred to as the "digital pins") are positioned in the fourth registered model using the first computer terminal 20 (e.g. by the dental surgeon).

Thus, at step s132 a 3-dimensional digital model comprising digital representations of the patient's teeth, the patient's jawbones, the radiological guide 84, the fork 26, the third plaster cast 82, the first base plate 38, the digital implants 50, the digital teeth 48 and the digital pins is produced. This digital model is hereinafter referred to as the "further digital implant model".

Figure 15 is a schematic illustration (not to scale) of a side view of certain elements of the further digital implant model 86. For purposes of clarity, digital representations of the fork 26, the radiological guide 84, and the patient's jawbone are not shown in Figure 15.

For convenience and ease of understanding, in Figure 15 the digital representations of real entities are indicated by the reference numeral assigned to that real entity, and vice versa.

In this embodiment, digital representations of the three securing pins (i.e. the three digital pins) are indicated in Figure 15 by the reference numeral 88.

In this embodiment, the digital pins 88 are inserted/positioned into the further digital implant model 86 in the same way as the digital implants 50, i.e. such that the digital pins 88, for example, avoid nerves or weak portions of bone in the patient's jawbone.

An axis for each of the digital pin 88 is shown in Figure 5 as a dotted line and indicated by the reference numeral 90. At step s134, the further digital implant model 86 is sent from the first computer terminal 20 (at the dental surgery 12) to the third computer terminal 22 (at the CNC drill facility 14).

At step s 36, the further digital implant model 86 is processed by the third computer terminal 22 to produce a digital model of a base plate, hereinafter referred to as the third base plate.

In this embodiment, this is done as described above at step s44 of Figure

3.

Figure 6 is a schematic illustration (not to scale) of the digital model of the third base plate 92.

In a corresponding way to the digital model of the second base plate 54 described above with reference to Figure 7, the digital model of the third base plate 92 comprises a digital representation of a plate which is the same shape as the first base plate 38 and a plurality of tubular portions 58.

In this embodiment, the digital model of the third base plate 92 further comprises three additional protrusions 94.

In this embodiment, each of the protrusions 94 is connected to the top surface of the third base plate 92.

Furthermore, in this embodiment the each of the three protrusions 94 comprises a tube-shaped portion. An axis of each of these tube-shaped portions of the protrusions 94 is coincident, at least in part, with a different one of the pin axes 90. Also, an internal diameter of a protrusion is substantially the same as an external diameter of a securing pin.

Furthermore, in this embodiment, each of the protrusions 94 is a tube of a size such that, were the digital representation of the third plaster cast 82 to be positioned on the top surface of the third base plate 92, each of the protrusions 94 would extend substantially up to, but not extend beyond, the top surface of the digital representation of the third plaster cast 82.

Also shown in Figure 16 are the pin axes 90. At step s138, the third computer terminal 22 is used to control the CNC drilling machine 24, such that the CNC drilling machine 24 produces the third base plate 92.

In this embodiment, this is done as described above for the second base plate 54 at step s46 of Figure 3.

At step s140, the third base plate 92, produced at step s102, is sent (e.g. via post or courier) from CNC drilling facility 14 to the dental laboratory 13.

At step s142, the collar 62, the first base plate 38, and the third plaster cast 82 are coupled together to form a seventh assembly.

In this embodiment, the seventh assembly is substantially the same as the third assembly 60 (formed at step s50 of the process of Figure 3 and described above with reference to Figure 8) with the third plaster cast 82 replacing the first plaster cast 40.

At step s144, silicone rubber cast of a negative impression of the third plaster cast 82, hereinafter referred to as the "further silicone rubber negative", is created.

In this embodiment, this is done as described above for the silicone rubber negative at step s52 of Figure 3.

At step s1 6, the collar 62, the further silicone rubber negative (produced at step s144), and third base plate 92 (produced at step S138) are coupled together to form an eighth assembly.

In this embodiment, the eighth assembly is substantially the same as the fourth assembly 64 (formed at step s54 of the process of Figure 3 and described above with reference to Figure 9) with the further silicone rubber negative replacing the silicone rubber negative 66, and the third base plate 92 replacing the second base plate 54.

In this embodiment, the eighth assembly comprises a cavity between the third base plate 92 and the further silicone rubber negative. This cavity is hereinafter referred to as "the further cavity". At step s148, a fourth plaster cast is formed by filling the further cavity in the seventh assembly with liquid plaster and allowing this liquid plaster to solidify.

In this embodiment, this is done in substantially the same way for forming the second plaster cast 70 at step s56 of Figure 3.

Figure 17 is a schematic illustration (not to scale) of the fourth plaster cast 96 formed at step s112. For convenience and ease of understanding, the fourth plaster cast 96 is shown in Figure 17 on its own. However, in reality, in this embodiment the fourth plaster cast 96 is coupled to the third base plate 92.

In this embodiment, the shape of the fourth plaster cast 96 is substantially the same as that of the third plaster cast 82 with cylindrical bores 72, and further bores 98 therein.

In this embodiment, as with the bores 72 in the second plaster cast 70 (described in more detail above with reference to Figure 10), the position (i.e. the orientations) of each of the bores 72 is substantially the same as the position of a respective digital implant 50 in the digital representation of the first plaster cast 40 (in the further digital implant model).

Also, in this embodiment the position (i.e. the orientations) of each of the further bores 98 is substantially the same as the position of a respective digital pin 88 in the digital representation of the third plaster cast 82 (in the further digital implant model 86).

At step s150, a metal rod is placed into each of the protrusions 94. In this embodiment, each of these metal rods is of a diameter that is substantially equal to the internal diameter of the protrusion into which it is inserted.

In this embodiment, the axis of each of the metal rod is placed into each of the further bores 98 is coincident with a pin axis 90.

At step s 5 , the radiological guide is sent from the dental surgery 12 to the dental laboratory 13.

At step s152, the radiological guide 84 is positioned onto the top surface of the fourth plaster cast (i.e. the surface of the fourth plaster cast that is a positive model of the lower dental arch of the patient). Furthermore, this is done such that the (negative) indentations in the radiological guide 84 mate with the (positive) corresponding protrusions of the patient's lower dental arch on the fourth plaster cast.

At step s154, along each of the respective rods that has been inserted into a further bore 98, a respective guide tube for a securing pin (which is, in effect, a metal tube, and which is hereinafter referred to as a "pin guide") is slid down, from the free end of that rod towards the non-free end of that rod, until the respective pin guide contacts the fourth plaster cast.

In this embodiment, each pin guide fits snugly around the rod it is slid along.

Furthermore, in this embodiment the axis of each of the pin guides is coincident with a pin axis 90.

At step s156, the radiological guide 84 is extended by applying relatively soft resin the surface of the fourth plaster cast.

In this embodiment, the additional resin is applied such that the additional resin is in contact with the radiological guide 84, and such that the external sides of each of the pin guides are substantially covered by resin, but such that the ends of the pin guide are not covered by resin.

At step s158, the resin applied at step s120 is allowed to harden.

At step s160, the rods that were inserted into the further bores 98 are removed from the further bores 98 of the fourth plaster cast and from the pin guides.

At step s162, the extended radiological guide (i.e. the original radiological guide extended with additional resin into which the pin guide tubes are set) is removed from the fourth plaster cast.

At step 164, the extended radiological guide is sent from the dental laboratory 13 to the dental surgery 1 .

At step s166, the extended radiological guide is placed into the patient's mouth such that the (negative) indentations in the extended radiological guide mate with the (positive) corresponding protrusions of the patient's lower dental arch.

At step s168, through the pin guides in the extended radiological guide (i.e. using the pin guides as drill guides); holes are drilled into the patient's jaw bone.

The formation of the extended radiological guide is such that the axis of each of the pin guides is in substantially the same relative direction to a pin axis 90. Thus, at step s168 holes are drilled into the patient's jawbone (to a desired depth determined from the further digital implant model 86) along a pin axis 90.

At step s170, the extended radiological guide is removed from the patient's mouth.

At step s172, a metal tube is inserted into each of the holes in the patient's jaw bone that were created at step s1 0.

In this embodiment, an internal diameter of each of the metal tubes that is inserted into each of the holes in the patient's jaw bone is substantially equal to that of a securing pin.

In other words, the metal tubes that are inserted into the holes in the patient's jaw bone at step s172 are such that securing pins can be inserted into them and the fit of the securing pin in the respective metal tube is relatively very secure.

At step s174, the patient's remaining teeth are removed from the patient's mouth.

At step s176, at the dental laboratory 13, the plaster representation of the patient's remaining teeth are removed (e.g. by filing away the plaster) from the fourth plaster cast.

At step s178, rods 74 are placed into each of the tubular portions 58 in the third base plate 92 (that has attached to it the fourth plaster cast).

In this embodiment, this is done as described above for the insertion of rods 74 in the tubular portions 58 of the second base plate 54, at step s58 of Figure 3. At step s180, along each of the respective rods 74, a respective drill guide tube 8 is slid down, from the free end of that rod towards the non-free end of that rod, until the respective drill guide tube 8 contacts the fourth plaster cast.

In this embodiment, this is done as described above for the placement of the drill guide tubes 8 with respect to the second plaster cast 70 above at step s60 of Figure 3.

At step si 82, a metal rod is placed into each of the protrusions 94, as described above with reference to step s 50.

At step s184, along each of the respective rods that has been inserted into a protrusions 94, a respective pin guide is slid down, from the free end of that rod towards the non-free end of that rod, until the respective pin guide contacts the fourth plaster cast. This is performed as described above with reference to step si 54.

At step s186, relatively soft resin is applied to the top surface of the fourth plaster cast.

In this embodiment, the soft resin is applied such that the surface of the fourth plaster cast that corresponds to the lower dental arch of the patient is covered by resin, and such that the external sides of each of the drill guide tubes 8 and pin guides are substantially covered by resin, but such that the ends of the drill guide tubes 8 and the pin guides are not covered by resin.

In this embodiment, step s186 is performed in a corresponding way to that described above at step s62 of Figure 3.

At step s188, the resin applied at step s148 is allowed to harden.

At step s190, the rods are removed from the bores 72 and the further bores 98 of the fourth plaster cast 70. The rods are also removed such that they are free of the drill guides 8 and the pin guides.

In this embodiment, step s190 is performed in a corresponding way to that described above at step s66 of Figure 3.

At step s192, the resin into which the drill guide tubes 8 and the pin guides are set is removed from the fourth plaster cast. The resin drill guide body, drill guide tubes 8, and three pin guides form the further drill guide.

Thus, a further drill guide is produced.

At step s194, the further drill guide is sent from the dental laboratory 13 to the dental surgery 12.

Thus, a further drill guide, and a process of producing the further drill guide, is provided.

In this embodiment, the further drill guide is used by inserting the further drill guide into the mouth of a patient for which the further drill guide has been produced. Securing pins are the inserted through the pin guides of the further drill guide and into the metal tubes present in the patient's jaw (i.e. the metal tubes that are inserted into the holes in the patient's jaw bone at step s172 of the method of Figure 13). The fit between the securing pins and the pin guides, and between the securing pins and the metal tubes in the patient's jawbone, are relative tight. Thus, the further drill guide is secured in the patient's mouth by the securing pins. Holes in the patient's jawbone are then drilled by the dental surgeon by inserting a drill through each of the drill guide tubes 8 and into the patient's jawbone. Each hole is drilled into the jawbone to a respective predetermined depth. Thus, drill holes are created in the patient's jawbone into which dental implants are then affixed.

In addition to the advantages mentioned above for the method of Figure 3, a further advantage provided by the above described method of producing the further drill guide is that, even if the patient has few (or no) remaining teeth the relatively secure fixing of the drill guide into the mouth of a patient is provided. This secure fitting of the drill guide is advantageously provided such that the axes of the drill guide tubes are aligned with the desired axes of the dental implants. The provided further drilling and method of producing the further drill guide are particularly useful with patients that have no, or few, remaining teeth and/or patients that are undergoing implantation of a complete dental arch. What will now be described is a further embodiment of a method of producing a drill guide 2.

In this embodiment, the CNC drilling facility 4, in addition to comprising the third computer terminal 22 and the CNC drilling machine 24, further comprises a laser scanner (which is hereinafter referred to as the "further laser scanner"). The further laser scanner is substantially the same as the laser scanner 16.

At step s200, the fork 26 is prepared (in the same way as at step s2 as described above with reference to Figure 3).

At step s202, the prepared fork 26 is inserted into the patient's mouth (in the same way as at step s4 as described above with reference to Figure 3).

At step s204, the patient bites down on the prepared fork 26, thereby creating an impression of the dental arch of the patient in the silicone rubber (in the same way as at step s6 as described above with reference to Figure 3).

At step s206, whilst the fork 26 is still in the patient's mouth and the patient is still biting down on the fork 26, one or more X-ray images of the patient's mouth are taken using the X-ray machine 18 (in the same way as at step s8 as described above with reference to Figure 3).

At step s208, the captured X-ray images (or data corresponding to the X- ray images) are sent from the X-ray machine 18 to the first computer terminal 20 (in the same way as at step s10 as described above with reference to Figure 3).

At step s210, the first computer terminal 20 processes the received X-ray images to create a 3-dimensional digital model of the patient's teeth, the patient's jawbones, and the fork 26 (in the same way as the first digital model is created at step s12 as described above with reference to Figure 3). This 3- dimensional digital model will hereinafter be referred to as the seventh digital model. At step s212, the fork 26 with attached the silicone rubber is removed from the patient's mouth (in the same way as at step s14 as described above with reference to Figure 3).

At step s214, a dental impression tray (hereinafter referred to as "the tray") is prepared. In this embodiment, the tray is a conventional dental impression tray that may, for example, be customised for the patient. The tray is prepared by applying to a viscous liquid material (e.g. liquid silicone rubber), which sets to become a solid after a certain amount of time.

At step s2 6, the prepared tray is inserted into the patient's mouth in a conventional manner.

At step s218, the patient bites down on the prepared tray, thereby creating an impression of the dental arch (in particular, the lower dental arch) of the patient in the viscous liquid material that has been applied to the tray.

At step s220, the tray is removed from the patient's mouth. The tray has in it a detailed impression of the (lower) dental arch of the patient.

At step s222, the fork 26 and the tray are sent from the dental surgery 12 to the dental laboratory 13.

At step s224, from the impression of the patient's lower dental arch in the tray, a plaster cast of the patient's lower dental arch, hereinafter referred to as the "fifth plaster cast", is created at the dental laboratory 13.

This is performed in a similar way to that described above at step s16 for the creation of the first plaster cast from the impression of the lower dental arch in the silicone rubber attached to the bottom surface of the U-shaped portion of the fork 26.

In this embodiment, the fifth plaster cast is created from the impression of the patient's lower dental arch in the tray. However, in other embodiments, the fifth plaster cast can be created from the impression of the patient's lower dental arch in the fork 26. In such other embodiments, the use of the tray may be omitted.

At step s226, the fifth plaster cast is scanned using the laser scanner 16. In this embodiment, data produced by the scanning of the fifth plaster cast by the laser scanner 16 are sufficient to allow for a 3-dimensional digital model of the fifth plaster cast to be created.

At step s228, data from the laser scanner 16 corresponding to the scanned fifth plaster cast are transferred from the laser scanner 16 to the second computer terminal 17.

At step s230, the second computer terminal 17 processes the received laser scanner data to create a 3-dimensional digital model of the fifth plaster cast. This 3-dimensional digital model of the fifth plaster cast is hereinafter referred to as the eighth digital model.

At step s232, the fifth plaster cast and the fork 26 (with the indented silicone rubber) are coupled together to form a ninth assembly.

In this embodiment, the ninth assembly comprises the fifth plaster cast and the fork 26 coupled together such that the fork 26 is positioned on to the top of the fifth plaster cast such that the silicone rubber 42 attached to the bottom surface of the fork 26, into which an indentation of the patient's lower dental arch has been formed, is in contact with the top surface of the fifth plaster cast (i.e. the surface of the fifth plaster cast that is the shape of the patient's lower dental arch). Furthermore, this is done such that the (negative) indentations in the silicone rubber 42 mate with the (positive) corresponding protrusions of the patient's lower dental arch on the fifth plaster cast.

At step s234, the ninth assembly is scanned using the laser scanner 16.

In this embodiment, data produced by the scanning of the ninth assembly by the laser scanner 16 are sufficient to allow for a 3-dimensional digital model of the ninth assembly to be created.

At step s236, data from the laser scanner 16 corresponding to the scanned ninth assembly are transferred from the laser scanner 16 to the second computer terminal 17.

At step s238, the second computer terminal 17 processes the received laser scanner data to create a 3-dimensional digital model of the ninth assembly. This 3-dimensional digital model of the ninth assembly (i.e. the fifth plaster cast and the fork 26 coupled together as described above) is hereinafter referred to as the ninth digital model.

At step s240, the eighth digital model (created at step s230) and the ninth digital model (generated at step s238) are registered by the second computer terminal 17. In this embodiment, this registration process comprises aligning the eighth and ninth digital models using surfaces common to both of those digital models (i.e. in the same way as the first and third digital models were registered at step s34 of Figure 3).

The registered eighth and ninth digital models are hereinafter referred to as the "fifth registered model", which comprises laser scanned images of the fifth plaster cast 40 and the fork 26 (with the fiduciary marker 32).

At step s242, the fifth registered model is sent from the second computer terminal 17 (at the dental laboratory 13) to the first computer terminal 20 (at the dental surgery 2), e.g. via email or over the Internet.

At step s244, the seventh digital model (generated at step s210) and the fifth registered model (generated at step s240) are registered using the first computer terminal 20. In this embodiment, this registration process is the same as that performed at step s38 of Figure 3 at which step the first digital model and the first registered model are registered, i.e. the image registration performed at step s244 comprises transforming one or more of the models such that the position and orientation of the fiduciary marker 32 in each of the digital models is substantially the same.

The digital model comprising the registered seventh digital model and fifth registered model is hereinafter referred to as the "sixth registered model".

The image of the fork 26 within the sixth registered model may be removed from the sixth registered model.

At step s246, digital implants 50 are positioned in the sixth registered model using the first computer terminal 20 (e.g. by the dental surgeon). This is performed in the same way as digital implants 50 are positioned in the second registered model, which is described in more detail above at step s40 with reference to Figure 3.

The digital model comprising the digital implants 50 positioned in the sixth registered model is hereinafter referred to as the "second further digital implant model".

At step s248, the second further digital implant model is sent from the first computer terminal 20 (at the dental surgery 12) to the third computer terminal 22 (at the CNC drilling facility 14).

At step s250, the fifth plaster cast is sent from the dental laboratory 13 to the CNC drilling facility 1 (e.g. via courier or post)

At step s252, the fifth plaster cast and a CNC machine workpiece-holding plate, hereinafter referred to as the "holding plate", are coupled together to form an assembly. This assembly is hereinafter referred to as the tenth assembly. The tenth assembly is placed by securing the fifth plaster cast onto the holding plate.

In this embodiment, the holding plate is a conventional workpiece-holding plate suitable for use with the CNC drilling machine 24, for example, a pallet of an EROWA(TM) workhold^'mg system.

At step s254, the tenth assembly is laser scanned using the further laser scanner (i.e. the laser scanner situated at the CNC drilling facility 1 ).

In this embodiment, data produced by the scanning of the tenth assembly by the further laser scanner are sufficient to allow for a 3-dimensional digital model of the tenth assembly to be created.

In this embodiment, the tenth assembly is formed and laser scanned (by the further laser scanner) at the CNC drilling facility 14. However, in other embodiments, the tenth assembly may be formed and/or scanned at a different location by different apparatus. For example, the tenth assembly may be formed and scanned (using the laser scanner 16) at the dental laboratory 13. At step s256, data from the further laser scanner corresponding to the scanned tenth assembly are transferred from the further laser scanner to the third computer terminal 22.

At step s258, the third computer terminal 22 processes the received laser scanner data to create a 3-dimensional digital model of the tenth assembly. This 3-dimensional digital model of the tenth assembly (i.e. the fifth plaster cast secured to the holding plate) is hereinafter referred to as the tenth digital model.

At step s260, the tenth digital model (created at step s258) and the second further digital implant model (generated at step s246 and sent to the third computer terminal 22 at step s248) are registered by the third computer terminal 22. In this embodiment, this registration process comprises aligning the models using surfaces common to both of those digital models (e.g. surfaces of the digital images of the fifth plaster cast).

The registered tenth digital model and second further digital implant model is hereinafter referred to as the "seventh registered model". In this embodiment, the seventh registered model comprises digital representations of the patient's jawbone, the fifth plaster cast, the digital implants 50, the holding plate, and (optionally) the fork 26. The images of the patient's jawbone may optionally be removed from the seventh registered model. In this embodiment the seventh registered model comprises a digital representation of the fifth plaster cast and the digital implants 50, the positions and orientations (i.e. the directions of the axes 52 of the digital implants 50) of which relative to the fifth plaster cast are the desired positions and orientations of dental implants in the mouth of the patient (as selected by the dentist).

At step s262, using the seventh registered model, the third computer terminal 22 is used to control the CNC drilling machine 24, such that, the CNC drilling machine 24 drills a plurality of holes/bores (hereinafter referred to as "drill holes") in the fifth plaster cast. The position, size and orientation of each of the drill holes in the fifth plaster cast is substantially the same as the position, size and orientation of a respective digital implant 50 in the digital fifth plaster cast (in the seventh registered model). The fifth plaster cast with the drill holes in it is hereinafter referred to as "the drilled plaster cast".

At step s264, the drilled plaster cast, produced at step s262, is sent (e.g. via post or courier) from CNC drilling facility 14 to the dental laboratory 13.

At step s266, a metal rod is placed into each of the drill holes in the drilled plaster cast.

In this embodiment, each metal rod is of a diameter that is substantially equal to the diameter of the drill hole into which it is inserted (i.e. in this embodiment, substantially the same as a diameter of a dental implant). Also, each metal rod is inserted into a respective drill hole such that the metal rod extends away from the top surface of the drilled plaster cast.

Furthermore, in this embodiment, each metal rod is inserted into a respective drill hole such that the axis of that rod is substantially coincident with the axis of that drill hole.

Thus, after step s266, each of the drill holes in the drilled plaster cast has placed within it a respective rod 74. Each rod 74 has a non-free end that is positioned within a drill hole, and a free end, opposite to the non-free end, that is distal from the drilled plaster cast.

At step s268, along each of the respective rods 74, a respective drill guide tube 8 is slid down, from the free end of that rod 74 towards the non-free end of that rod 74, until the respective drill guide tube 8 contacts the drilled plaster cast.

At step s270, relatively soft resin is applied to the surface of the drilled plaster cast that corresponds to the lower dental arch of the patient.

At step s272, the resin applied at step s270 is allowed to harden.

At step s274, the rods 74 are removed from the drill holes and from the drill guides 8, At step s276, the resin into which the drill guide tubes 8 are set is removed from the drilled plaster cast. Thus, the drill guide 2 is formed.

At step s278, the drill guide 2 is sent from the dental laboratory 13 to the dental surgery 12 (for use_.by the dentist).

Thus, a further embodiment a method for producing the drill guide 2 is provided. In addition to many of the advantages mentioned above for the method of Figure 3, a further advantage provided by the above described further embodiment is that the method tends to have fewer steps than conventional methods and so be simpler to perform.

Apparatus, including the computer terminals for implementing the above arrangement, and performing the method steps described above, may be provided by configuring or adapting any suitable apparatus, for example one or more computers or other processing apparatus or processors, and/or providing additional modules. The apparatus may comprise a computer, a network of computers (e.g. a network of computers spread across a number of different locations), or one or more processors, for implementing instructions and using data, including instructions and data in the form of a computer program or plurality of computer programs stored in or on a machine readable storage medium such as computer memory, a computer disk, ROM, PROM etc., or any combination of these or other storage media.

It should be noted that certain of the process steps depicted in the flowcharts of Figures 3 and 13 and described above may be omitted or such process steps may be performed in differing order to that presented above and shown in the Figures. Furthermore, although all the process steps have, for convenience and ease of understanding, been depicted as discrete temporally- sequential steps, nevertheless some of the process steps may in fact be performed simultaneously or at least overlapping to some extent temporally. Furthermore, it should be noted that any of the method steps performed in an above described embodiment may be replaced by any of the method steps from a different embodiment, or those steps from the different embodiment may be performed in addition to the steps of the embodiment in question, such that the same functionality (e.g. the production of the drill guide) is provided.

In the above embodiments, the patient is an adult male human. However, in other embodiments the patient is a different type of patient. For example, in other embodiments, the patient is a human child and/or a female human. In such embodiments, any of the apparatus may be modified or changed so as to accommodate the different type of patient. For example, a smaller sized fork may be used for a child.

In the above embodiments, the dental guide has the features described above with reference to Figure 1. Furthermore, in the above embodiments, the dental guide is made of those materials specified above. However, in other embodiments, the dental guide comprises additional features instead of or in addition to those described above (for example, a different number of drill guide tubes). Furthermore, in other embodiments, the components of the drill guide are made of different appropriate materials. In other embodiments, the functionality provided by the components of the drill guide is supplied by one or more different appropriate features.

In the above embodiments, the shapes of the various pieces of apparatus used in the methods (e.g. the shape of the fork or a base plate), and the shapes of the various entities created or produced during the methods (e.g. the shape of a plaster cast) are as specified above. However, in other embodiments the shape of one or more of the various pieces of apparatus and/or one or more of the various entities is different to that described above such that the above described functionality is provided.

In the above embodiments, the materials of which the various pieces of apparatus used in the methods are made (e.g. resin of the fork or a base plate), and the materials used to create or produce the various entities created or produced during the methods (e.g. the plaster used to create a plaster cast, or the silicone rubber used to create a silicone rubber negative) are as specified above. However, in other embodiments the materials of which one or more of the various pieces of apparatus are made and/or the materials used to make one or more of the various entities is different to that described above such that the above described functionality is provided.

In the above embodiments, certain of the method steps are performed at a specified location (e.g. either the dental surgery of the CNC drilling facility) and/or by a specified party (e.g. by the dental surgeon or an assistant to the dental surgeon). However, in other embodiments a method step may be performed at a different location or locations. Also, in other embodiments a method step may be performed by a different party or parties.

In the above embodiments, images are generated using the X-ray machine, and using the laser scanner. Images from these two image sources are then registered to create a registered model into which dental implants are digitally inserted. However, in other embodiments, instead of or in addition to one or both of the X-ray machine and the laser scanner, one or more different types of imaging device is used to create appropriate images. The images from any of the image sources may then be registered (e.g. if they are of good quality) to create a registered model into which dental implants are digitally inserted.

For example, in other embodiments, a CT scanning machine, an MRI machine and/or an ultrasound machine is used instead of or in addition to the X- ray machine to capture images of the internal structure of the portion of the dental arch of the patient.

For example, in other embodiments, a contact 3D scanner and/or CMM machine is used instead of or in addition to the laser scanner to create the digital model of the physical model of the dental arch (i.e. the digital model of the first plaster cast).

In other embodiments, dental implants are digitally inserted into an image prior to registering that image with other images. In other embodiments, images from only one image source are used to construct the digital model into which dental implants are digitally inserted.

In the above embodiments, images are registered together using the fiduciary marker on the fork as a reference. In the above embodiments, the fiduciary marker is a 3D bar code. In the above embodiments, the fiduciary marker is positioned relatively centrally on the fork. However, in other embodiments the images from the multiple image sources may be registered in a different way, for example, using a different reference point or set of reference points. In other embodiments, the fiduciary marker is a different type of feature or set of features, for example, a set of three or more tungsten (or other radio- opaque material) plugs may be positioned at different respective points in the body of the fork. These plugs may then be used to register images from the different image sources. In other embodiments, the fiduciary marker is positioned at a different point on the fork.

In the above embodiments, a base plate comprising one or more tubular portions is produced using a CNC drilling process based on a digital model. However, in other embodiments such base plates are produced by a different appropriate method, for example, stereo lithography or rapid prototyping.

Claims

1. A mould part (54, 92) for a mould, the mould being for producing a cast (70, 96) of at least a portion of a dental arch of a patient, the cast (70, 96) comprising a bore (72) in the cast (70, 96), the position of the bore (72) in the cast (70, 96) of the dental arch being substantially the same as a predetermined desired position in the dental arch, the mould part (54, 92) comprising:

a base portion; and

a protrusion (58) extending from the base portion; wherein

the protrusion (58) defines the bore (72) in the cast (70, 96).

2. A mould part according to claim 1 , wherein the predetermined desired position in the dental arch is a desired position for a dental implant in the dental arch.

3. A mould part according to claim 1 or 2, wherein the protrusion (58) is a hollow tube.

4. A mould part according to any of claims 1 to 3, the mould part further comprising a further protrusion (94) extending from the base portion, wherein the further protrusion (94) defines a further bore (98) in the cast (70, 96), the position of the further bore (98) in the cast (70, 96) being substantially the same as a predetermined desired position for a securing pin in the dental arch; and

the securing pin is a pin with which a dental drill guide (2) is secured to the dental arch during a procedure of implanting a dental implant into the dental arch.

5. A method of manufacturing a mould part (54, 92) according to any of claims 1 to 4, the method comprising:

providing a digital model of the dental arch;

inserting a digital representation of a dental implant (50) into the digital model such that the position of the digital representation of the dental implant (50) in the digital model is the desired position for the dental implant in the dental arch; and

using the digital model and the digital representation of a dental implant (50) inserted therein, producing the mould part (54, 92) such that the position of the protrusion (58) on the base portion is dependent on the position of the digital representation of the dental implant (50) in the digital model.

6. A method according to claim 5, wherein the step of, using the digital model and the digital representation of a dental implant (50) inserted therein, producing the mould part comprises, using a CNC milling machine (24), milling a piece of material into the shape of the mould part (54, 92).

7. A method according to claim 5 or 6, wherein the step of providing digital model of the dental arch comprises:

capturing one or more X-ray images of the dental arch; and

producing the digital model using said one or more X-ray images.

8. A method according to any of claims 5 to 7, wherein the step of providing a digital model of the dental arch comprises:

creating a physical model (40, 82) of the dental arch of the patient;

using a laser scanner (16), capturing one or more laser scan images of the physical model (40, 82) of the dental arch; and

producing the digital model using said one or more laser scan images.

9. A method according to claim 8, wherein the step of providing a digital model of the dental arch further comprises positioning the physical model (40, 82) with respect to a further base portion, the further base portion being substantially the same shape as the base portion; wherein

the step of capturing one or more laser scan images of the dental arch comprises capturing one or more laser scan images of the physical model of the dental arch and the further base portion; and

the digital model produced using said one or more laser scan images comprises a digital representation of the further base portion.

10. A method according to claim 8 or 9 when dependent on claim 7, wherein the step of providing a digital model of the dental arch comprises registering the digital model produced from the one or more X-ray images and the digital model produced from the one or more laser scan images.

11. A method according to claim 10, wherein

the step of capturing one or more X-ray images of the dental arch comprises positioning a reference member (32) with respect to the portion of the dental arch of the patient, and capturing one or more X-ray images of the portion of the dental arch of the patient and the reference member (32);

the digital model produced from the one or more X-ray images comprises a digital representation of the reference member (32);

the step of capturing one or more laser scan images of the dental arch comprises positioning the reference member (32) with respect to the physical model (40, 82) such that position of the reference member (32) with respect to the physical model (40, 82) is substantially the same as that of the reference model with respect to the dental arch in the X-ray images; the digital model produced from the one or more X-ray images comprises a digital representation of the reference member (32); and

the step of registering the digital model produced from the one or more X-ray images and the digital model produced from the one or more laser scan images comprises registering the reference member (32) in the digital model produced from the one or more X-ray images and the reference member (32) in the digital model produced from one or more laser scan images.

12. A method according to claim 1 , wherein:

the reference member (32) is coupled to a U-shaped member;

the step of positioning the reference member (32) with respect to the portion of the dental arch of the patient comprises positioning the U-shaped member with respect to the portion of the dental arch such that an impression of the dental arch is created in the U-shaped member;

the step of positioning the reference member (32) with respect to the physical model comprises positioning the U-shaped member such that the physical model complements the impressions made in the U-shaped member by the dental arch.

13. A method according to claim 1 , wherein the reference member (32) is a single fiduciary marker coupled to the U-shaped member.

14. A method according to claim 12 or 13, wherein the reference member (32) is positioned centrally on the U-shaped member.

15. A method according to any of claims 12 to 14, wherein the step of creating a physical model (40, 82) of the dental arch of the patient comprises, using the impression of the dental arch in the U-shaped member, casting the physical model of dental arch.

16. A method of producing a dental drill guide (2), the drill guide (2) comprising a drill guide tube (8) for guiding a drill during a procedure of implanting a dental implant into a portion of a dental arch of a patient, the method comprising:

using a mould comprising a mould part (54, 92) according to any of claims 1 to 4, producing a cast (70, 96) of at least a portion of the dental arch; and

using the cast (70, 96), producing the dental drill guide (2); wherein the position of the drill guide tube (8) in the drill guide (2) is dependent on the position of the bore (72) in the cast (70, 96).

17. A method according to claim 16, wherein the mould part (54, 92) is produced by the method of any of claims 5 to 15.

18. A method of producing a digital model of a portion of a dental arch of a patient, the method comprising:

capturing one or more images of the internal structure of the portion of the dental arch of the patient;

using the captured one or more images, producing a first digital model of the portion of the dental arch;

creating a physical model (40, 82) of the portion of the dental arch of the patient;

using the physical model, producing a second digital model of the portion of the dental arch; and

combining at least some elements of the first digital model and at least some elements of the second digital model to produce the digital mode) of a portion of a dental arch of a patient.

19. A method according to claim 18, wherein the one or more images used to produce the first digital model of the dental arch of the patient are X-ray images.

20. A method according to claim 18 or 19, wherein the step of, using the physical model (40, 82), producing a second digital model of the portion of the dental arch comprises:

measuring the physical model (40, 82) using a range sensor (16); and using the range sensor measurements, producing the second digital model.

21. A method according to claim 20, wherein the range sensor (16) is a laser scanner.

22. A method according to any of claims 18 to 21 , wherein the step of combining comprises registering the first digital model and the second digital model.

23. A method according to any of claims 18 to 22, wherein

the step of capturing one or more images of the internal structure of the portion of the dental arch comprises positioning a reference member (32) with respect to the portion of the dental arch of the patient, and capturing one or more images of the reference member (32) and the internal structure of the portion of the dental arch;

the first digital model comprises a digital representation of the reference member (32); the step of using the physical model (40, 82), producing a second digital model of the portion of the dental arch comprises positioning the reference member (32) with respect to the physical model (40, 82) such that position of the reference member (32) with respect to the physical model (40, 82) is 5 substantially the same as that of the reference member (32) with respect to the dental arch in the images of the internal structure, and producing the second digital model such that the second digital model comprises a digital representation of the reference member (32); and

the step of combining comprises registering the reference member (32) o in the first digital model and the reference member (32) in the second digital model.

24. A method according to claim 23, wherein:

the reference member (32) is coupled to a U-shaped member;

5 the step of positioning the reference member (32) with respect to the portion of the dental arch of the patient comprises positioning the U-shaped member with respect to the portion of the dental arch such that an impression of the dental arch is created in the U-shaped member;

the step of positioning the reference member (32) with respect to the physical model (40, 82) comprises positioning the U-shaped member such that the physical model (40, 82) complements the impressions made in the U- shaped member by the dental arch.

25. A method according to claim 24, wherein the reference member (32) is a single fiduciary marker coupled to the U-shaped member.

26. A method according to claim 24 or 25, wherein the reference member (32) is positioned centrally on the U-shaped member.

27. A method according to any of claims 24 to 26, wherein the step of creating a physical model (40, 82) of the dental arch of the patient comprises, using the impression of the dental arch in the U-shaped member, casting the physical model of the dental arch.

28. A method of manufacturing a mould part (54, 92) for a mould, the mould being for producing a cast (70, 96) of at least a portion of a dental arch of a patient, the cast (70, 96) comprising a bore (72) in the cast (70, 96), the position of the bore (72) in the cast (70, 96) of the dental arch being substantially the same as a predetermined desired position for a dental implant in the dental arch, the mould part comprising a base portion and a protrusion (58) extending from the base portion, wherein the protrusion (58) defines the bore (72) in the cast (70, 96), the method comprising:

producing the digital model of a portion of a dental arch of a patient using a method according to any of claims 18 to 27;

inserting a digital representation of the dental implant (50) into the digital model such that the position of the digital representation of the dental implant (50) in the digital model is the desired position for the dental implant in the dental arch; and

using the digital model and the digital representation of a dental implant

(50) inserted therein, producing the mould part (54, 92) such that the position of the protrusion (58) on the base portion is dependent on the position the digital representation of the dental implant (50) in the digital model.

29. A method according to claim 28, wherein the step of, using the digital model and the digital representation of a dental implant (50) inserted therein, producing the mould part (54, 92) comprises, using a CNC drilling machine (24), milling a piece of material into the shape of the mould part (54, 92).

30. A method of producing a dental drill guide (2), the dental drill guide (2) comprising a drill guide tube (8) for guiding a drill during a procedure of implanting a dental implant into a dental arch of a patient, the method comprising:

manufacturing a mould part (54, 92) using a method according to claim

28 or 29,

using a mould that comprises the mould part (54, 92), producing a cast (70, 96) of at least a portion of the dental arch; and

31. A method of producmg a dental drill guide (2), the dental drill guide (2) comprising a drill guide tube (8) for guiding a drill during a procedure of implanting a dental implant into a dental arch of a patient, the method comprising:

inserting a digital representation of the dental implant (50) into the digital model; and

using the digital model and the digital representation of a dental implant inserted therein, producing the drill guide (2), wherein the position and orientation of the drill guide tubes (8) in the drill guide (2) is dependent on the position and orientation of the digital representation of a dental implant (50) in the digital model.

32. A digital model of a portion of a dental arch of a patient, the digital model being produced by a method according to any of claims 18 to 27.

33. Apparatus for use during a dental imaging process, the apparatus comprising:

a portion for inserting into the mouth of a patient and for, when the portion is inserted into the mouth of the patient, securely engaging with at least a portion of the dental arch of the patient; and

a fiduciary marker (32), the fiduciary marker being detectable by a first imaging system (18) and a second imaging system (16); wherein

the first imaging system (18) is for capturing images of an internal structure of the dental arch; and

the second imaging system (16) is configured to image an outer surface of entities it is used to capture images of.

34. Apparatus according to claim 33, wherein the apparatus is a dental fork (26).

35. Apparatus according to claim 33 or 34, wherein the first imaging system (18) is an imaging system selected from a group comprising: an X-ray imaging system, an MRI system, and an ultrasound imaging system.

36. Apparatus according to any of claims 33 to 35, wherein the second imaging system (16) is an imaging system selected from a group comprising: a laser scanner, a contact 3D scanner, and a CMM machine.

37. Apparatus according to any of claims 33 to 36, wherein the fiduciary marker (32) is positioned at or proximate to the centre of the portion.

38. Apparatus according to any of claims 33 to 37, wherein the fiduciary marker (32) is a 3D barcode.

39. Apparatus according to any of claims 33 to 38, wherein the portion is a U-shaped member.

40. Apparatus according to claim 39, the apparatus further comprising a handle (30) positioned at the bottom of the U-shaped member.

41. Apparatus according to any of claims 33 to 40, wherein, when the portion is inserted into the mouth of the patient, the portion securely engages with at least a portion of the dental arch by means of a viscous liquid material (42) applied to a surface of the portion and into which the dental arch is impressed.

42. Apparatus according to any of claims 33 to 41 , wherein the portion comprises a plurality or holes (34) or indentations in a surface of the portion, the holes (34) or indentations being for facilitating the attachment to the surface of a viscous liquid material (42).

43. A drilling method comprising:

using a digital model, the digital model comprising a digital representation of a dental arch of a patient and a digital representation of a dental implant (50) positioned within the digital representation of the dental arch, controlling a drilling machine (24) to drill a bore into a physical model of the dental arch; wherein

the bore is drilled such that a position and orientation of the bore in the physical model is dependent upon the position and orientation of the digital representation of the dental implant (50) in the digital representation of a dental arch.

44. A method according to claim 43, wherein the drilling machine (24) is a CNC drilling machine.

45. A method according to 43 or 44, wherein,

the digital model further comprises a digital representation of a holding plate; during drilling, the physical model is coupled to the holding plate such that the relative position of the physical model and the holding plate is substantially the same as the relative position, in the digital model, of the digital representation of the dental arch and the digital representation of the holding plate.

46. A method of producing a dental drill guide (2), the dental drill guide (2) comprising a drill guide tube (8) for guiding a drill during a procedure of implanting a dental implant into a dental arch of a patient, the method comprising:

providing a digital model, comprising a digital representation of the dental arch and a digital representation of a dental implant (50) positioned within the digital representation of the dental arch;

providing a physical model of the dental arch;

performing the drilling method of any of claims 43 to 45; and

using the physical model with the bore drilled therein, producing the dental drill guide (2); wherein

the position of the drill guide tube (8) in the drill guide (2) is dependent on the position of the bore in the physical model.

47. A method according to claim 46, wherein the step of providing the digital model comprises: producing a digital model of the dental arch using a method according to any of claims 18 to 27; and

inserting a digital representation of the dental implant (50) into the digital model of the dental arch.

48. A mould part for a mould, the mould part being substantially as described herein with reference to the accompanying Figures.

49. A method of manufacturing a mould part for a mould, the method being substantially as described herein with reference to the accompanying Figures.

50. A method of producing a dental drill guide, the method being substantially as described herein with reference to the accompanying Figures.

51. A method of producing a digital model of a portion of a dental arch of a patient, the method being substantially as described herein with reference to the accompanying Figures.

52. A dental fork substantially as described herein with reference to the accompanying Figures.

53. A drilling method substantially as described herein with reference to the accompanying Figures.