BACKGROUND ART

Dental implants are root replacement devices used in dentistry to provide a support for prosthetic teeth or other dental appliances. They are screwed into a suitably prepared site in the jaw bone with the screw serving as a fixture onto which a prosthetic tooth or other dental appliance may be mounted. Dental implants have been in use for over 40 years and have been extremely successful in treating patients with tooth loss. The efficacy and success of dental implants and the rising demand for cosmetic dentistry worldwide acros all age groups has led to an exponential growth in the industr and to a very l arge number of different types or brands of dental implants that have been made available.

This growth has resulted in a vast array of design variations in dental implants with incompatibility existing between denial implants from different manufacturers. In general, the industry is characterized by a lack of standardisation in the devices and systems that are used at the clinical level, and this incompatibility at the prosthetic interface is compounded by the large range of possible dental implants. This poses an extreme challenge for the clinician when faced with re-servicing existing dental implants, such as is required when replacing a broken prosthetic tooth. Frequently, the availability of proper dental records is lacking, especially when patients move locations, and so it may be impossible in those circumstances to reliably identify the nature of the existing dental im lant in need of re-servicing.

The current method of identification relies largely on radiographic imaging. However, identification of the brand of a den tal implant screwed in the jaw bone using radiographic images of brand specific features is difficult and unreliable and requires the clinician to stay abreast of a myriad of dental im plant systems that are regularly changing. Radio frequency identification (RFID). systems are well known in some other industries for their usefuiftess in quickly and reliably identifying small objects. RFID systems conventionally include an RFID tag which may be programmed and interrogated, by a reader device. The RFID tag has an integrated circuit with a radio transceiver and. antenna. The integrated circuit may be programmed by the reader device to contain identification and other application specific information. RFID systems compared to other identification means, such as physical identifiers, offer the significant advantage of storing a large amount of digital information in a physically small form .

US Patent Application Publication No, 2009/0155744 Al (by Jaiiclali) discloses a dental implant identification system based on the concept of using radio frequency identification (RFID) devices within dental implant screws as a means of identification. Other than disclosin that an. RFID tag is po si tioned at the bottom of an internal bore within the dental implant screw, no information is provided in Janda!i as to the necessary technic al detai ls of the RFID tag and i ts antenna. In particular, there is no disclosure of the structure (or configuration) and orientation of the RFID tag and its antenn within the screw.

Currently, there are no known dental implants that are being manufactured with RFID tags. The common structure of RFID tags in the time leading up to Jandali consisted of a tag mounted on carrier substrate with the antenna printed on a carrier board. This is inexpensive to construct and the flat planar configuration is suitable for many applications. However, the magnetic field coupling from a reader antenna to the tag antenna and the resulting recei ved voltage supplying the tag will be ex tremel weak owin to the small iat planar configuration of the tag antenna. The received voltage (or received signal strength) will be too weak to power up the circuitry within the tag which requires a niioirnurn of I volt in most tags. Furthermore, tag antennae having a flat plana contigutation present difficulties in the manner in which they may he located within a confined space, such as within the cylindrical bore of a dental implant screw.

The use of RFI.D tags when placed in a very small., completely enclosed, metal cavity is extremely challenging. Placing an RFJD tag withi a very small space at the bottom of a cavity within a dental implant screw with a volume typically of <5 mm poses severe performance limitations. These performance limitations arise from the srnall size of the antenna and the effect of the surrounding metal on the performance of the radio transceiver and antenna.

Dental implants ar e typically constructed of titanium or zirconium and associated alloys since these materials provide the necessary strength and ^' biocompatibility requirements for prolonged and effective use. These materials, and any other material of similar conductivity and thickness,, provide a shield that significantly attenuates the radio frequency signal The amount of attenuation is an exponential function of the skin depth of the materials) used to construct the dental implant.

Further deterioration of the received signal strength occurs due to the close proximity of the metal to the tag antenna which decreases the resonant signal by degrading the antenna's electrical properties. The often deleterious effect of materials (especially conductive materials) in close proximity to antennas is well, known. Due to these extremely challenging conditions, RF1D devices have not yet been used for the purpose of identification of dental implants. The present inventors ha ve recognised that RFJD system offer the potential to address all the problems associated with current method of identifyin dental implants and have also recognised that the vast information storage capability of RFID systems may be used for patient dental record and other user information as desired by the ' linician.

The present inventors have also recognised that any RFID systems to be used for identifying dental implants can be either of the non-con tact type or of the contact type.

However, the present in venters have equally recognised that for RFID systems to perform at a sufficiently high level when used for identifying dental implants by wa of RFID tags positioned therewithin and for storing information, significant changes to the conilgiiratioii (i.e. structure and/or orientation) of at least the RFID tag are needed.

It is a first discovery of the present inventors that, for a non-contact type of RFID system useful for identifying dental implants, a coil structure of the RFID tag antenna positioned within a dental implant is more advantageous than a flat planar structure, and that such an RFID ta antenna coil must be orientated in a particular manner within a dental implant to optimize the magnetic field coupling from a reader antenna to the tag antenna and hence optimise the received signal strength needed to power up the circuitry within the tag. It has been found by the present inventors that such a non-contact type of RFID system useful for identifying dental implants may utilize a reader antenna that can either be positioned outside the denta l implant or inside a tag containing ca vity of the dental implant. It is a second discovery of the present inventors that, for a contact type of RFID system useful for identifying dental implants, an RFID tag in the form of an integrated circuit (iC) between two contact electrodes and positioned inside a cavity of a dental implant can be used, and that such an RFID tag circuit may be activated b contact with a tip of a reader contact probe inserted within the cavi ty of th e dental implant. it has been found by the present inventors that* by putting these discoveries into practical implementation in an RFID system for identifying dental implants., the aforementioned problem s and shortcom i ngs of the prior art can be overcome or at least substantially ameliorated.

SUMMARY OF INVENTION ^'

According to one aspect of a first form of the present invention, there is provided a dental implant identification system of the non-contact type, comprising:

( a) a dental implant havin a radio frequency identification tag which stores

informatio for identification of the dental implant, the tag including a tag antenna coil having a first coil axis,

(b) a reader device for acti vating the tag and for reading the information stored on the tag when the information is transmitted from the tag upon activation thereof, the reader device including a reader antenna coil having a second coil axis, and

(e) information processing means for processing the identification information read by the reader device,

wherein the radio frequency identification tag is so configured within the dental implant to provide an optimal reading of the identification ..information whe the reader antenna coil is positioned alongside the ta antenna coil and the second coil axis is substantially aligned with the first coil axis, and when the reader device activates the tag.

Preferably, the radio frequency identificatio tag is located inside a. cavity within a main body of the dental implant.

In one preferred arrangement, tire reader device is configured such that the reader antenna coil, when positioned aiongside the tag antenna coil and when the first coil axis and the second coil axis are siibstantial ly aligned, is outside the main body of the dental implant. In another preferred arrangement, the reader device is configured such that the reader antenna coih when positioned alongside the tag antenna coil and when the first coil axis and the second coil axis are substantially aligned, is inside the cavity of the main body of the dental implant .

Preferably, the information processing means is com pater associated with the reader device for accessing a database containing infonriatioii relating to the identification information. it is preferred that the radio frequenc identification tag further includes an information storage element and an integrated control circuit electrically connected between the tag antenna coil and the storage element and operable to activate the storage element in response to a voltage being generated in the tag antenna coil when the tag antenna coil and the reader antenna coil are magnetic field coupled.

In a preferred form, the identification information is stored on a microchip.

The tag antenna coii preferably operates as a passive power supply for the tag. In one preferred embodiment, the reader device has a single reader antenna coil.

In another preferred embodiment, the reader device has two reader antenna coils.

According to another aspect of the first form of the present invention, there is provided a dental implant for engagement to a ja bone, the dental implant comprising a main body having a longitudinal axis and an outer threaded surface for screwing the main body into the jaw bone in the direction of the longitudinal ax is, the main body having an abutment for connecting a prosthetic tooth thereto, a cavity within the main body, a radio frequenc identification tag positioned within the cavit for storing infotittatiori for identification of the implant, the ta including an integrated circuit and a tag antenna coil having a tag coil axis that is orientated perpendicularly to the longitudinal axis of the main body, whereby the tag antenna coil of the radio frequency identification tag is able to be magnetic field coupled with a reader antenna coil of a reader device when the reader antenna coil is positioned alongside the tag antenna coil, and when a reader coil axis of the reader antenna coil is- orientated substantially perpendicuiarly to the longitudinal axis of the main body, the magnetic field coupling resulting in a voltage being generated in the tag antenna coil that is of a signal strength sufficient to cause the integrated circuit within the tag to be powered up so that the mfomtation can fee read by the reader device, According to one aspect of a second form of the present in ven tion, there is provided a dental implant identification system of the contact type, comprising:

(a) dental implant having a main body, a cavity within the main body, and a radio frequency identification tag located inside the cavity, the radio frequency identification tag storing information for identification of the dental implant and including an integrated circuit between two contact electrodes,

(b) a reader device for activating the tag and for reading the information stored on the tag when the information is transmitted from the tag upon activation thereof, the reader device includin a reader contact, terminal, and

(c) informatio processing means for processing the identification information read by the reader device,

wherein the radio frequency identification tag is so configured within the dental implant to provide an optimal reading of the identification information when the reader contact terminal is inserted int the cavity and contacted against one of the contact electrodes, and when the reade device activates the tag.

Preferably, the information processing means is a computer associated with the reader device for accessing a database containing information relating to the identification information. in a preferred form, the identificat on information is Stored on a microchip. According to another aspect of the second form of the present in vent ion, there i provided a dental implant for engagement to a jaw bone, the dental implant comprising a main body having a longitudinal axis and an outer threaded surface for screwing the main body into the jaw bone in the direction of th longitudinal axis, the main body having a abutment for connecting a prosthetic toot thereto, a cavity' within the main body, a radio frequency identification tag positioned within th cavity tor storing i formation for identification of the implant, the tag including an integrated circuit between two contact electrodes, whereby one of the contact electrodes of the radio frequency identification tag is able to be contacted by a reader contact terminal of a reader device when the reader contact terminal is inserted within the cavity, the contact resulting in a voltage being generated in the integrated circuit that is of a signal strength sufficient to power up the integrated circuit so that the information can be read by the reader device. Preferably, the radio frequency identification tag includes a printed circuit board on which is mounted an integrated circuit between a first contact electrode and a second contact electrode.

It is preferred that the printed circuit board and the integrated circuit are covered by a protective mouldi g that has a high electrical resistance.

In preferred form, the first contact electrode presents contact surface, such as in the shape of a conical depression, facing towards an opening of the cavity, and the second contact electrode presents a contact surface, such as in the shape of a conical proj ection, facing towards, and abutting, a base (or closed end) of the dental implant.

I a particularly preferred embodiment, when a contact tip of a powered on reader device is inserted through the openin of the cavity of the dental implant and the reade contact terminal o the reader device, is pressed against, or contacts, the first contact electrode of the radi frequenc identification tag, arid a reader positioning collar of the reader device is wedged against, or contacts, the opening of the cavity in the main body, the interconnection of the aforementioned components closes an electrical circuit along which current flows between the reader device and the radio frequency identification tag of the dental implant, There has been thus outlined, rather broadly, the more important features of the invention i n order that the detailed description thereof that follows may he better understood and put into practical effect, and in order that the present contribution to the art may be better appreciated. There are additional features of the invention that will be described hereinafter. As such, those skilled in the art will appreciate that the conception, upon which the

disclosur is based, may be readily utilized as ^' the ^' basis for designing other devices, systems and methods for carrying out the objects of the present invention. It is

important, therefore, that the broad outline of th e i nvention described above be regarded as including such equivalent constructions in so far as they do not depart from the spirit and scope of the present invention.

BRIEF DESCRIPTION QF THE DRAWINGS The invention will be better understood and objects other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the accompan ing drawings, in which:

Figure 1 is a schematic front sectional view of a dental implant identification system of the non-contact type showing only a dental implant and a single reader antenna coil, the configuration being according to a first embodiment of the invention,

Figure 2 is a perspecti ve view of a reader device containing a single reader antenna coil that ca be a&ed with the denial implant of the system shown in Figure I,

Figure 3 is a side view of the reader device show in Figure 2, Figure 4 is a front sectional view through A-A of the reader device shown in Figure 3,

Figure 5 is a top view of the reader device shown in Figure 2, Fig ure 6 is a side secti onal view through D- D of the reader device sh own i n Figure 5,

Figure 7 is a schematic front sectional view of a dental implant identification system of the non-contact type showing only a dental implant and two reader antenna coils at respective opposed sides of the dental implant, the two reader antenna coils being positioned so as to have their axes aligned ^' with the axis of a tag antenna coil positioned inside the dental implant, the configuration of all of these com onents being according to a second embodiment of the invention.

Figure S is a perspective view of a reader device containing two reader antenna coils that can be used with the dental implant of the system shown in Figure 7,

Figure 9 is a side view of the reader device shown in Figure 8,

Figure 10 is a front sectional view through A-A of the reader device shown in Figure 9 _S

Figure 1 1 is top view of the reader device shown in Figure 8,

Figure 12 is a side sectional view through A-A of the reader device shown in Figure 1 1 Figure 3 is a block and circuit diagram showing the key electronic components and circuitry design of a reader device that can be used in any of the first and second embodiments of the invention, and showing its interaction with the radio frequency identification tag of the dental implant and with the information processing means, Figure 14 is an alternate block and circuit diagram similar to that of Figure 13, Figure 15 is a schematic front sectional view of a dental implant identification system of the non-contact type showing only a tag antenna coil of a dental implant and two reader antenna coils at respective opposed sides of the tag antenna coil, the tvvo reader antenna coils being positioned s as to have their axes offset from the axis of the tag antenna coil positioned inside the dental implant, the configuration of all of these components being according to a third embodiment of the invention.

Figure 16 is a graph showin (magnetic field induced voltage) signal strength recei ed on the tag antenna coil versus degree of alignment of axes of two reader coils at respective opposed sides of the- dental implant of the system shown in Figure 1.5,

Figure 17 is a schematic top sectional view of a dental implant identification system showing only a dental implant and twelve reader antenna coils at respective evenly spaced apart locations radially around the side of the dental implant, the twelve reader antenna coils being positi oned so that at least two- of those coil s have their axes al igned substantially wit the axis of the tag antenna coil positioned inside the dental implant, the configuration of all of these components being according to a fourth embodiment of the invention, Figure 18 is schematic top sectional view of a dental Implant identification system showing only a dental implant- and six reader antenna coils divided into two groups of three coils at respective opposed sides of the dental implant, the six reader antenna coils being positioned so that at least two of those coils have their axes aligned substantially with the axi of the tag antenna coil positioned inside the dental implant, the configuration of all of those components being according to a fifth embodiment of the invention.

Figure 19 A, 1 B, 19C and 1.9D are schematic views of a double sided circuit board for use in the radio frequency identification tag of a dental implant that ma be used in any of the first to fifth embodiments of the invention, Figure 20 is a schematic side sectional view of a dental implant identification system of the non-contact type sho wing only a dental implant and a non-contact tip of reader device- electrically connected to a match circuit, the configuration being according to a sixth embodiment of the invention..

Figure 21 is a schematic side view of a radio frequency identification tag of a dental implant that ma be used in the dental implant identification system of the non -contact type shown in Figure 20 _» Figure 22 is a schematic end view of the radio frequency identification tag shown in Figure 21,

Figure 23 is a perspective view of a reader device that may be used in a dental implant identification system of either the non-contact type or the contact type,

Figure 24 is a schematic side sectional view of a dental implant identification system of the contact type showing only a dental implant and a contact ti of a reader device electrically connected to a match circuit, the configuration being according to a seventh embodiment of the invention,

Figure 25 is a schematic side view of a radio frequency identification tag of a dental implant that may be used in the dental implant identification system of the contact type shown in Figure 24. Figure 2.6 is a block and circuit diagram showing the key electronic components and circuitry design of a reader device that can be used in the sixth embodiment of the invention, and showing its interaction with the radio frequency identification tag of the dental implant and with the information processing means, and Figure 21 is a block and circuit diagram showing the key electronic components and circuitry design of a reader device that can be used in the -seventh embodiment of the invention, and showing its interaction with the radio frequency identification tag of the dental implant and with the information processing means.

MODES FOR CARRYING OUT THE INVENTION

The dental implant identification system of the non-contact type show schematically in Figure 1 has a dental implant 10 and a single reader antenna coil 34 of a portable reader device, both of these components being in first configuration for use of the system, of the invention.

The dental implant 10, which is adapted for engagement to a jaw bone, has a generall cylindrical main bod 14 of shank that is typically formed of a medical grade metal, such, as titanium. The body 14 has a longitudinal axis 16 and an outer threaded surface 18 which is used for screwing the body 14 into the jaw bone i the directio of the longitudinal axis 16. The body 14 has an upper driving feature, such as a recess or socket, configured to receive a driving tool used to serewably engage the body into the bone.

An abutment or head portion extends from an upper axial end 20 of th body and i used for connecting prosthetic tooth or crown thereto. There is a sealed or closed cavity 22 within the body 1 , and positioned immovably inside the cavity 22 is a radio frequency identification (RFID) tag 24 or transponder which store information for identification of the dental implant 10, The RFID tag may alternatively be embedded within a non-hollow body, such as by a process which moulds a non-metal lie body around the. tag.

The RFID ta is able to withstand gamma radiation sterilisation, autoclave sterilisation and other conditions it ma encounter in normal use, both before and after oral installation, and must be capable of operating in or adjacent to metal objects . The Rf ID tag 24 includes a receiver transmitter element which, in this embodiment suited to low frequency R.FID systems, is in the form of a magnetic inductio coil, referred to hereinafter a a tag antenna coil 26. in high frequency applications, the receiver transmitter element is in the form of a dipole antenna.

The tag antenna coil 26, which is typically a smalt wound fertile coil, has a ta coil axis 27 which is orientated perpendicularly to the longitudinal axis 16 of the body 14 so that the axis 27 passes throug the thinnest part (side walls) of the body 14 (as shown in Figure I) attd is perpendicular to the jaw line. The orientation of the tag antenna coil 26 perpendicular to the longiiiichiiai axis 16 of the body 14 will generally reduce the available size of the coil 26 since the coil's axis 27 is no longer parallel to the body's axis 16. However, this unusual orientation is important in that it: provides the shortest distance to the reader's coil 34 and the radio frequency signal emanating from the tag antenna coil 26 passes through the smallest amount of metal of the body 14. Such factors will optimise performance and compensate for the smalle size of the tag antenna coil 26.

The importance of the tag coil axis 27 being orientated perpendieuiar!y to the jaw line will also become apparent later in this specification. Tire upper driving feature of the body may be used to rotate the body until such an orientation is achieved, with the changing orientation being monitored b a visual indicator on the driving tool or by preliminary use of the reader device of the system to positio the reader antenna coil at the desired perpendicular location and then monitor the strength of the radio frequency signal it receives from the tag antenna coil as the. body is being rotated until a maximum signal strength is received.

The reader antenna coil 34 is a component of the portable reader device 32 or scanner (shown in Figs. 2 to 6) which can read or decode (o interrogate) the information stored in the RFID tag 24 The reader device 32 is of the inductively magnetic field coupled type which use coil antennae and are effective over short distances. By utilising the passive HD concept, the reader device 32 can provide a non-invasive method for the identification of information relating to the dental implant

The reader device 32 includes a transmitter receiver element which, i this embodiment is in the form of a power coil, referred to hereinafter as a reader antenna coil 34. In high frequency applications, the transmitter receiver element is in the form of a dipole transmitter. The reader antenna coil 34 is housed in a arcuate or generally J-shaped probe compartment 35 of the reader device 32, The arcuate shape of the probe compartment is to complement the shape of the jaw so that the probe compartment ca "wrap around" the crown and its interconnected dental implant, thus bringing the reader antenna coil 34 as close as possible alongside, and in axial alignment with, the tag antenna coil positioned inside the body 14 of the dental implant

The reader antenna coil 34 is connected to conversion circuit which includes an oscillato diat energises the coil 34 and an analogue-to-digital converter that converts variations in the current passing along the coil 34 to digital signals. The coil 34 has a reader coil axis 36 which, in use, is ideally aligned with the tag coil axis 27 (as shown in Figure I). The coil 34 transmits signals to. and receives signals from, an integrated circuit mounted on an electronies board 38 housed hi a handle 40 of the reader device 32, A. rechargeable battery 42 for powering the reader device is also housed in the handle 40. Hie components in the handle 40 are operably connected to the components in the probe compartment 35 through an extension arm 44.

The KFID tag 24 is passivel powered by electromagnetic wave transmissions from the reader antenna coil 34 of the reader device 32 and received by the tag antenna coil 26. In this way, the RFID tag 24 does not require an internal power supply thai can be exhausted over time. The information storage element 30 of the RFID tag 24 is an integrated circuit that is configured to generate a digital signal corresponding to the uiformation that is stored in encoded form in the element 30. The received strength of this digital signal is maximised when the reader coil axis 36 is aligned with the tag coil axis 27, and this is more readil achieved due to the perpendicular orientation of the tag coil axis 27 to th jaw line, which means that the part of the reader device housing the reader antenna coil can be positioned similarly peipendictilarly to the jaw line, where there is the most available space. Upon activation of the EHD tag 24 by the reader device 32, this digital signal is fed back through the control circuit 28 which varies the resistance in the tag antenna coil 26 to transmit the encoded information stored in. the element 30 as a digital signal to the reader antenna coil 34. The integrated circuit in the reader device 32 is correspondingly configured to translate the digital signal to a human readable format

The key electronic components and circuitry design of a reader device 50 that can be used in various embodiment of the invention, and its interactions with die RFID tag 24 of the dental implant 10 and with a desk top computer 62 and server 64 of the information processing means, are shown in. Figure 13. Reader device 50 has a uniquely designed transceiver extension interface circuit 52 which enables high performance electromagnetic field operation for extremely small sized RFID tags, such as tag 24. The extensioH interfaee circuit 52 includes a transceiver circuit 54 that has two reader antenna coils 55, 56 and a resonant capacitor 57. An alternat block and circuit diagram showing key electronic components and circuitry design of a reader device that is similar to that in Figure 33 i shown Figure 14. hi more general terms, die reader device 32 transmits electromagnetic waves and the RFID tag in the dental implant is tuned to receive those waves through electromagnetic induction when the ta antenna coil and the reader antenna coil are magnetic field coupled. The RFID tag draws power from the field created by the reader device and uses it to power the circuits of its microchip. Tire microchip then modulates the waves that the RFID tag transmits back to the reader device, which converts the received waves into digital data. The digital data, as received, contains identification information on the particular dental implant being interrogated. This information may then be communicated wireless ly or b USB coimeetion to information processing means, such as a computer, for processing the information into a human readable format.

The information cannot only relate to the dental implant itself, such as information as to the manufacturer:, part number, batch number, and manufacture date, o any other unique ^' identifier of the dental implant, all of which occur before the information, storage element 30 is incorporated into the dental implant; but it can include patient information, date of oral installation, inspection dates and other information about events that have occurred in the life of the dental implant, both prior to and after its engagement to a jaw bone.

In this case, remote writing features can b provided to the information storage element 30 that allow writing to a dental implant that has an already incorporated information storage element or has been orall installed, such as by radio frequency transmission. To achieve this, the control circuit 28 would be modified to permit switching the information storage element between "read" and "write" modes. The desired information can be written to the dental implant from the RFID tag .24 or from the information processing means, The information processing means can be server or host computer associated wi th the reader device and operable by the clinician, and which can access a database containing information relating to the identification information. Such a database can be stored locally on the host compute or can be accessed via local area network or via the internet as a centralised database. The database could be provided as a "Cloud" service. After the decoded RFID tag information is sent from the reader device to the computer, either wirelessly or via a USB connection, the computer compares that information with the information contained on the database and provides- useful information to the clinician or other user of the system, such as if the information is identical , information arising from this interrogation can be stored on the reader device and/or uploaded on the computer and or added to the database.

The dental implant identification s>¾teni of the non-contact typ show schematically in figure 7 has a dental implant 100 and two reader antenna coils 102, 104 of a portable reade device 06 (shown in Figures 8 to 12), tire coils 102, 104 being positioned at respecti ve opposed sides of the dental implant 100 so as to have their axes aligned with the- axis of a tag antenna coil 26 positioned inside the dental implant 100, all of these components being in a second configuration for use of the system of the in vention.

The main structural differences between this system as shown in Figures 7 to 12 and the system as shown in Figures 1 to 6 are that this system employs two reader antenna coils 102, 104 (not one such coil 34), and those coils 102, 104 are housed accordingly in a generall U-shaped probe compartm ent 108 ( not a generall J -shaped probe compartment 35} of the reader device 106. There are other, more minor, structural differences which (along with their minor functional consequences) would be readily apparent to the skilled addressee of this specification and which are a consequence of the main structural differences indicated above. However, all other structural features (and their functional consequences) of the system as shown in, and described with reference to. Figures 1 to ό are present in the system as shown in Figures 7 to 12, and so those other structural features (and their functional consequences) need not be again described herein with reference to Figures 7 to 12 but they are shown in Figures 7 to 12 with the same numerals used to identify those features in Figures 1 to 6. The skilled addressee of this specification would readily understand from the description and drawings of the structural features (and their functional consequences) of the syste as shown in Figures 1 to 6 that the structural differences, both main and more minor, that are present or would be readily apparent to the skilled addressee, would not substantially affect the working operation or use of the system as show in Figures 7 to 12 as compared to the working operation or use of the system as shown in, and described with reference to, Figures 1 to 6„ but may affect the performance outcome of the system as shown in Figures 7 to 12 as compared to that i Figures ί to < . For example, the strength of the signal received by the reader device 106 employing the two reader antenna coils 102, 104 to transmit matching m-phase signals to the tag antenna coil 26 is effecti vely doubled as compared to the received signal strength of the reader device 32 employing one reader antenna coil 34, The same considerations relating to structural differences, working operation or use, and perjonnanee outcomes apply to the systems sltown schematically in Figures 15, 17 and 18, The dental implant identification system of the non-contact type shown schematically in Figure 15 is the same as that shown in Figures 7 to 12 except that its two reader antenna coils 70, 72 have respective axes which, whilst they are parallel to the axis of the tag antenna coil 26, are deliberately offset from the tag antenna coil axis. This third. Configuration for use of the system of the inv ention is based on the fact that, in practice, precise alignment of the reader antenna coil axis with the tag antenna coil axis will be difficult to achieve. To broaden the effective response and improve robustness to misalignment, the coil axes of a system employing multiple reader antenna coils can he deliberately misaligned. When, as shown in Figure 15, the axes of two reader antenna coils are misaligned, both wi th each oth e and with the axi s of the tag antenna coil, by an offset ($>)■, this will reduce die maximum (achievable) received signal strength (and so weaken the best case performance outcome) but increase the range of misalignment for which a useful and sufficientl strong signal will be received by die reader antenna eoil (as shown .graphically in Figure 1.6). Therefore, the system of Figure 15 trades off peak performance ith improved performance under mis lignment.

The dental implant identification system of the non-contact type shown schematically i Figure 1 7 has a dental implant 1.50 and twelve reader antenna coils 152 of a portable reader device, the coil 152 being positioned at respective evenl spaced apart locations radially around the side of the dental implant so that at least two of those coils have their axes aligned substantially with the axis of the tag antenna coil 26 positioned insi de the dental implant 150, all of these com onents ^' being in. a fourth configuration for use of the system of the in vention.

The use of an increased number of twel ve reader antenna coils in this arrangement is to further mitigate the effect of rotational misalignment. Any rotational misalignment will be mitigated since additional sets of coils will become aligned axialiy with the axis of the tag antenna coil This configuration may have limitations in some applications where this large number of coils and their location in the reader device may prevent the reader antenna coils being brought close enough to the RFID tag inside a dental implant, because of obstruction by objects suiTounding the dental implant, to receive a useful and sufficiently strong signal.

In those applications where mis problem exists, it may be overcome by reducing the number of reader antenna coils in the reader device and concentrating those remaining coils into two distinct and separated groups.

The dental implant identification system of the non-contact type shown schematically in Figure 18 has a dental implant 200 and six reader antenna coils 202 of a portable reader device, the coils' 202 being divided into two groups of three coils at respective opposed sides of the dental implant so that at least two of those coils have their axes aligned substantially with the axis of the ta antenna coil 26 positioned inside the dental implant 200, all of those components being in a fifth configuration for use of the system of the invention. The use of a decreased number of six reader antenn coils in this arrangement is to overcome the problem of obstruction by objects surrounding the dental implant, although the syste of Figure 1.8 trades off peak performance to overcome this problem because of the now mor limited degree of rotation of the reader device for which a useful and sufficiently strong signal will be received. The double sided circuit board 250 shown in Figures 19 A, 1 B, 19C and 1.9D is used in the M tag 24 or any other RFID tag of a dental implant described above. The key electronic components are solder mounted on opposite surfaces of the circuit board 250. On one surface (see Figure 1 A) of the circuit board 250 is a receiver coil. (LI ) (or tag antenna coil) 26, On the other opposite surface (see Figure 19C) of the circuit board 250 is a resonant capacitor (C 1 ) 252 and an RFID integrated circuit (III) 254.

The circuit board 250 is encapsulated as shown in Figure 19D and the circuit board routes signals between the key electronic components 26, 252 and 254.

The dental i mplant identification system of the non-contact type show schematically in Figure 20 has a dental implant 260 and a non-contact tip 262 of a reader probe 263 (shown i Figure 23), both of these components being in a sixt configuration for use of the system of the invention.

The dental implant 260 has a non-contact RFID tag 264, which is cylindrical in shape, positioned immovably inside an open cylindrical cavity 266 within the main body of the dental implant 260. The non-contact tip 262 of the reader probe 263 includes, at its leading end, a reader antenna coil 268 (which is a transmitter recei ver element in the form of a power coi!) ₄ a coil positioning spring 270 and a reader positioning collar 272, The reader antenna coil 268 is electrically connected to, and receives its power through, wiring 273 from a match circuit 274 along which current flows (as shown by the direction of the arro ws in Figure 20).

The non-contact RFID tag 264 (as shown in more detail in Figures 21 and 22) includes a surface mounted coil inductor, hereinafter referred to as a tag antenna coil 276, and a integrated circuit 278, both of which are mounted on a printed circuit board 280 and covered by protective plastic moulding 282 which has high electrical resistance. In use, the contact tip 262 of the "powered on" reader probe 263 is inserted through the opening of the cavity 266 of the dental implant 260 until further i sertio is prev nted by the reader positioning collar 272 becoming wedged in the opening, and the tag antenna coil. 276 and the reader antenna coil 268 are magnetic field coupled. The non- contact RFID tag 264 is passively powered by electromagnetic wave transmissions front the reader antenna coi l 268 of the reader probe and received by the tag antenn coil 276.

As shown in Figure 23, the reader probe 263 has a handle 282 to which is connected a detachable nozzle 284 from which the non-contact tip 262 extends. As indicated above, the nozzle 284 is for use with the dental implant 260.

Figure 23 also shows a detachable nozzle 286 which ca alternatively be connected to the handle 282, and from which a contact tip 288 extends. The nozzle 286 is for use with a dental implant 290 as shown in, and to be hereinafter described with reference to, Figure 24.

The dental implant identification, system of the contact type shown schematically in Figure 24 has a dental implant 290 and the contact ti 288 of the reader probe 263 (shown in Figure 23), both of these components being in a seventh configuration for use of the system of the invention .

The dental implant 290 has a contact RFID tag 292 (shown in Figure 25), which is cylindrical in shape, positioned immovably inside an open cylindrical, cavity 294 within the main body of the dental implant 290.

The tip 288 of the reader probe 263 includes a reader contac terminal 296 at its leading end, a terminal pressure spring 298, and a reader positioning collar 300. The reader contact terminal. 296 is electrically connected to, and receives its power through, a current supply wiring 301 from a secondary side of an electrical transformer 302, and the reader positioning collar 300 is electrically connected b a current return wiring 303 to the transformer 302. The contact RFID tag 292 includes a printed circuit hoard 304 on which is mounted an integrated circuit 305 between two contact electrodes 306, 308. The printed circuit board 304 and the integrated circuit 305 are covered by a protective plastic moulding 309 which has high electrical resistance. The contact electrod 306 presents a contact surface in the shape of a conical depression facing towards the opening of th cylindrical cavity 294, and the contact electrode 308 presents a contact surface in the shape of a conical projection facin towards, and abutting, the base (or closed end) of the dental implant 290. Alternatively, tire contact electrode 308 may present contact surface in the shape of a ring facing outwardl and abutting a cylindrical wall region of the cavity at the base of the dental im lant 290.

In use, the contact tip 288 of the "powered on" reader probe 263 is inserted through the opening of the cavity 294 of the dental implant 290, and the reader contact terminal 296 is pressed against, or contacts, the contact electrode 306 of the contact RFID tag 292 with low contact resistance and with a level of pressure regulated by the terminal pressure spring 298, until further insertion is prevented b the reader positioning collar 300 becoming wedged in the opening. The interconnection of the aforementioned components closes an electrical circuit along which current flows (as shown by the direction of the arrows in Figure 24) between the transformer 302 of the reader probe 263 and the contact RFID tag 292. The transformer 302 is connected to a match circuit 310.

The handle 282 of the reader probe 263 includes one or more buttons and a display, such as an LED display, connected to a microcontroller for facilitating the operation of the reader probe 263 by the user. The reader probe 263 is connected by wired or wireless means to a personal computer or other device operated through a microprocessor, such as a smart phone.

The reader probe 263 is "powered on" by a suitable power source which Supplies power to standard operating components for RFID reader devices and either the match circuit 274 or the match circuit 310, depending on whether the dental implant identification system is of the non-contact type or of the contact type, housed within the reader probe 263.

Both the reader probe 263 of the portable reader device and ei ther the non-contact RFID tag 264 or the contact RFID tag 292, operate preferably in the 13,56 MHz ISM band.

The main electronic components and circuitry design of the reader probe 263 which utilizes the non-contact tip 262, and its interactions with the RFID tag 264 of the dental implant 260 and with a desk to computer 62 and server 64 of the infOnnatio processin means, are shown in Figure 26, Reader probe 263 has a transceiver extension / interlace circuit 312 which enables high performance electromagnetic field operation for extremely small sized RFID tags, such as tag 264, and also includes tlie match circuit 274 and the reader antenna coil 268 of the non-contact tip 262. The main electronic components and circuitry design of the reader probe 263 which utilizes the contact ti 288, and its interactions with the RFID tag 292 of tlie dental implant 290 and with a desk top computer 62 and server 64 of the information processing means, are shown in Figure 27. Reader probe 263 has a transceiver extension / interface circuit 312 which enables high performance electromag etic field operation for extremely small sized RFID tags, such as tag 292, and also includes the match circuit 310, the transformer 302 and the reader contact, terminal 296 of the contact tip 288.

The desk to computer 62 in both of the embodiments of Figures 26 and 27 could alternatively be a "laptop" or "note book" or other computer, or even a "tablet" computer or a smart phone.

As will be apparent to the skilled addressee of this specification, with the ver large number of different types or brands of dental implants that ha ve been made available, the dental implant identif cation system of the present invention provides an important aid to the dental professional by assisting them to identify which dental implant has been installed in a patient who .requites restorative or other procedures on the implant. Mot only can this information be used at the clinical level, it can also be used for inventory control, forensic identification and other types of investigation. It will also be readil apparent to persons skilled i the art that various modifications may be made in detail s of design and construction of the embodiments of the dental implant ide tification system and devices^ and in the steps of using the systems and devices described above _s without departing from the scope or ambit of the present invention.

The reference in this specificatio to any prior publication (or irifonttation derived fiom it), or to an matter which is known, is not, and should not be taken as an

acknowledgement or admission or any form of suggestion that that prior publication (or information derived .from it) or known matter forms part of the common general knowledge in the field of endeavour to whic h this specification relates before the filing date of this- patent application.