WO2010095037A1

WO2010095037A1 - A method of producing conjoined implant systems with friction locking

Info

Publication number: WO2010095037A1
Application number: PCT/IB2010/000476
Authority: WO
Inventors: Ninian Spenceley Peckitt; Gurvinder Singh Virk
Original assignee: Computergen Implants Limited
Priority date: 2009-02-23
Filing date: 2010-02-23
Publication date: 2010-08-26

Abstract

There is described a conjoined implant system comprising a first component part which is a maxillary or mandibular host implant provided with one or more (female) docking holes; a second component part which is a tenant implant like a dental crown, a bridge or a denture provided with one or more (female) docking holes; and a third component part comprising a bridging component provided with one or more (male) pegs adapted to fit into the one or more docking holes of the first and the second component parts; provided that the pegs and holes are tapered with respect to each other.

Description

A Method of Producing Conjoined Implant Systems with Friction Locking

Field of the invention

The present invention relates to a method of producing conjoined implant systems with friction locking and to a surgical implant system related thereto.

Background of the invention

Implantable siu gical and dental implant systems manufactured from,, for example, surgical grade litarriuin and titanium based alloys_* have the ability to fuse to bone (osscomtegration).

Fabricated multiple rnetai components in surgical implant systems sometimes require to be conjoined to create a hybrid functioning implant system. This may involve the joining of an osseointegrated component (implant fixture) with a compatible fmplaαt abutment e.g. a titanium abutment, or other part e.g. a device or superstructure onto which may be placed an epithesis (an orthopaedic correction of a deformed extremity) or an external prosthetic component (e.g. eye. nose. lip cheek ear, hearing aid or other iuncn^'oning prostheses - digits limbs- etc) or a dental abutment / superstructure system onto which may be fixed an artificial dentition of single dental crown units, removable or fixed denial bridgework, overdetuure or other dental / surgical device.

Methods υf Joining Implant Com/nmente

Current methods of joining implant components include woJdiπg_s brazing, soldering, riveting, screwing, tacking, bolting, cementation and chemical bonding, following preparation of die contact siuface e.g. with etching techniques. Furthermore, conjoined components must possess mechanical properties which meet {he service ai»d safety requirement specifications of die end product implant.

Intensive research and development of tbe techniques of, for example, titanium joining lias resulted in practical solutions that ar<? technique dependent.

Welding

Welding is a major melhσd employed in joining titanium. Initial difficulties especially related Io the high temperatures required, have been overcome with technology development.

WiIh careful choice of materials,, sound welds embodying strøngϋi, ductility, and resistance to impact, loading can be achieved with titanium. Low interstitial content, as indicated by chemical analysis, should permit a sound weld with good properties as-welded, provided that additional contamination is not introduced by the Surrounding atmosphere,, and the beta content is not too high.

With low interstitial content, unalloyed titanium is readily weldable. However, the typical alpha- beta alloys, containing manganese, chromium, iron, vanadium, and molybdenum, when welded usually have a much lower bend ductility and notch toughness. This beud ductility and notch toughness decrease severely as uic total alloy content of beta stabili^iag elements exceeds 3%. However, such alloys may contain aniounls of the alpha stabilizers, alumimuin and tin, to permit a greater alloy content without further loss of ductility. Resistance Weldmg

Spot, sca∑n, and flash welding are all resistance-welding processes, which have been successfully applied to ϊitMiutn, Resistance welding is a pressure welding process wherein the heat k obtained by the resistance of the melal to (he flow of electric current.

1« spot welding tliu heat is restricted to a fairly small section of the lapped area of the parts to be conjoined. In spot welding two copper electrodes are simultaneously used to clamp the metal components together and to pass current through the mctais. Wben the current is passed through the electrodes., heat is generated due to the higher electrical resistance where the surfaces contact each other.

In seam weldings instead of pointed electrodes,, wheel-shaped electrodes roll along and often feed the workpiece, making it possible to make long continuous welds.

In flash welding, the heat is obtained from an arc established bclween the pieces to be welded by electrical resistance. When sufficient foeat For proper welding is obtained, pressure is applied to consummate the weld. This procedure is applicable to both alloyed and unalloyed titanium. In the case of the alloyed material there is some loss in ductility which may be restored by post-heat <realπκnt. Pressure Welding

In this method of welding, the metal is conjoined under high pressure with or without heat, to cold welding titanium, the metal surfaces are brought into intimate contact, and high pressures are applied to produce a high strength bond across the weld. The deformation, in {he form of upset or bulged nicla), is removed u> restore the original shape,

The pressures required are dependent upon the sι>.e and type of material. The process also requires at leasi 85% deformation for a high strength bond and thus necessitates using ductile materia]. Fairly strong bonds of titanium with itself,, copper, and steel have been produced.

Fusion Welding

The most common method of welding is the fusion technique, Fusion weldόjg involves various processes in which metals are conjoined together by contact in the molten state at the surfaces to be conjoined. This is accomplished either with or without the use of a filter metal and without the application of mechanical pressure.

The most common production method employs a welding (oroh designed Io permit an inert gas to flow through it, This technique develops an envelope of protective gas around the electrode and weld metal. The envelope moves with the torch and thus is constantly covering the new weld Dioiten metal puddle. However, this movement of the protective envelope, tmcovers the solidified, but still hot, weJd deposit and here some contamination may be collected, Helium is a particularly effective inert gas for fusion welding because it is lighter than either air or argon and consequently lies up against the underside of a weld. Due to the very great reactivity of titanium at elevated temperatures, the inert-gas protective envelope must be of high purity or it will in itself be a source of contamination,

Fusion welding of titanium, therefore, differs from that of other metals in that due to the high reactivity of titanium, it requires careful control of the surrounding atmosphere. The problems encountered in joining titanium to dissimilar metals by welding methods still τcinain to be resolved. However, joining of titanium to dissimilar metals by methods other than welding has shown better promise.

Brazing and Soldering

Where welding is neither practical nor economically feasible, it may be desirable to consider llie brazing or soldering of titanium. Brazing is a joining process whereirt a filler metal is used which has a meltϊπg point greater than e.g. 43O⁰C (UO(VF), but less than that of the materials to be conjoined.

Soldering, on the other hand, employs a tiller metal which melts at less than 430⁰C (800⁰F) and is commonly applied to tfιin*gauge material or wire.

CM^' the conventional inelals employed in the brazing of steel, only pure silver and aluminium have been applicable to titanium with satisfactory results. High strength aluminium alloys have produced brittle impractical jøύiis. Other metals such as zinc and tin will not adequately wet the titanium surface.

Gun Brazing Of the many methods for gas brazing conventional roetaϊs, only the use of oxyacety.ene gas has been found effective to date with titanium in that the gas employed does not embrittle the material. With a similar brazing method, but employing pure aluminium in place of pure silver, reasonably ductile but low strength joints are obtained.

In gas brazing aluminium to titanium, the titanium part is dipped into molten aluminium; the aluminium-clad titanium is then brazed to the aluminium part by conventional aluminium brazing techniques.

Furnace Brazing By brazing in a furnace with a protective atmosphere, the complexity of the gas brazing procedure is simplified. In place of the usual special fluxes, a simple mjxftire of silver chloride and potassium chloride or manganese chloride and pøtøssiutifl chloride is sufficient, Λlso_t muitiple brazing operations are capable of being simultaneously performed with heat applied uniformly to all surfaces of the part,

These advantages, however, are applicable only to small parts due to the limitations of furnace dimensions. Longer lime cycles are required in fiimace brazing because of the absence of localized heating. This results in thicker melting layers which somewhat decrease ductility and strength, especially with an aluitiinium-brazed joint.

Resistance Brazing Resistance brazing differs from resistance welding in that a low melting metal is placed between (he two surfaces to be brazed. Water-cooled copper electrodes have proved preferable to graphite aud other high electrically resistant but contaminating materials. Titanium in itself has sufficient electrical resistance necessary to heat the surfaces. With high etøclrical currents, short lin.es_> and low pressures, strengths superior to those obtained in gas braκing have been achieved with a pure silver brazed joint.

Soldering

The successful soldering of titanium lias been denioαstτaied. To obtain a rapid aud economical joint requiring HtUe strength, soldering is preferable to other methods of joining Samples should be prepared by depositing of thin films of «.g, the chloride salts of silver, copper, or tin on titøaiutn, This is usually accomplished by heating the chloride salt-coated titanium in a helium atmosphere furnace. The resultant flϊm can he wetted with either a 60% tin-40% lead or a 50% tin~50% lead solder employing commercial soldering fluxes.

Mechanical Joining Rivaling

Riveting is the joining of two metals by means of metal fasteners which mechanically lock themselves in position, This method of joining is especially applicable fo the joining of highly stressed parts, the forming of a discontinuous joint, and in cases where ihe work is accessible from only one side.

Titanium is being riveted with stainless sfeel. MonelΦ, high strength aluminium, or titanium rivets using conventional riveting techniques, With titanium rivets the driving time is increased 65% over that employed, for example, for high strength aluminium rivets. Rivets are cotd- driven_t aud rivet holes require the maintenance of close tolerance to insure good gripping. When it is necessary to have flush-head rivets_* dimpling is carried out at temperatures of 260 to 3 l 5^ϋC (SOO to 600⁰F).

When riveting titanium to dissimilar metals or when riveting titanium with aluminium rivets, precautions must be taken to suppress galvanic corrosion.

Screw Fixation Screwing titanium parts together is a common method of joining dental abutments to the osseointegrated dental implant fixture, and fixed dental crowns / bridgework to the dentai abutment system, This system of abutment / dental crown attachment may give up to a 15-50% failure rate, in thai screws Jtacfure or loosen with tune and under the influence of occlusal and masticatory forces. The use of a torque wrench and the use of additional adhesive reduces lhes>e problems In addition, a bacterial leak from the fixture well that receives the abutment screw in dental implant fixtures may be responsible for halitosis and the subsequent resorption of the alveolar creslal bone in the coronal part of the supporting bone.

Tacking

Implant components e.g. Vicryl® mesh or other resorbable mesh systems (e.g. polylactate mesh), may be tacked to bone adjacent to any endo-osseous implant and used with guided bone regeneration techniques, e.g. The Infuse System®.

Bolting

In this method of joining, the mechanical bond can be readily removed without destrmction of the part. Titanium cau be conjoined to itself oi dissimilar metals with titanium bolts or with, e.g. cadmiuπvplated steel bolts.

With titanium bolts, the locknuts can be plated, e.g. with rhodium or silver, to prevent galling and seizing of rtie mit to the bolt Some increase in galvanic corrosion has been noted with the application of cadmium-plated listeners. Teflon® coatings on the tlireaded parts of a titanium boh haw been reported fo greatly reduce seizing and galling of titanium. Galvanic corrosion is also minimized by tne corrosion resistance or^" the Teflon®.

Cementation

Cementation of meωl dental crowns to metal abutments (e.g. with oxyphosphate and other dental cements) has been common practice in clinical dentistry. However, the cement fute eventually dissolves or fractures in the presence of saliva and/or occlusal loading, with the development of recurrent caries under the crown. Life expectancy of cemented crowns and bridges is about 1 Q- 15 years.

Chemical Bonding

Metal conditioners (primers) and an adhesive system exist for conditioning base metal alloys e.g. Acryl Bond, Alt- Bond 2 Primer B, Alloy iMnier, Cesead Kl Opaque Primer, fiye Sight Opaque Primer, Metatast Bonding Liner, Metal Primer il, and MR Bond, ϊsocyanato- and metliacryloxy- stlaiies promote Bis-GMA {the reaction product of bisphenol A a«d glycidyl methacrylate) adhesion, to titanium.

Siloc light-activated composite material (Artgtøss) is ont? example of a material which may be used as a bonding material.

lA)ckmg Taper Concept

Bicαn introduced the locking taper concept to implant dentistiy and the integrated abutment crown which was a major advance in that a light cured poJyceramte material was bonded to the tapered locking abutment, which was tapped into the female component - the dental implant fixture.

The Bϊcon System locking taper system relies upon friction to keep it intact. Assembly is achieved by driving a i .5 degree morse taper into a matching socket iii the implant. A high ciaKφLng force between the abutment and implant is generated by this action, Tim^'s ctømpiittg force is almost lateral to the axis of the implant and therefore almost normal or perpendicular to the friction plane. This means that lateral forces and moments about the afautroeut do not tend to wear down the surface asperity. This is also improved by the use of Ti-6A1-4V titanium alloy, which is considerably stronger and stiffer than commercially pure titanium, and cold welds better, particularly in the absence of oxygen (Buckley, J 981). The high friction force is the result of relative slip between the two friction surfaces occurring at high contact pressure. This results in the surface oxide layers breaking down and the asperity fusing, sometimes referred to as cold welding.

Summary of the laventioo

We have now developed a customised maxillofacial implant system with multipart hybrid adaptations which has appiicatioji to the maxillofacial region as wet! as other areas of implantofogy, such as orthopaedics and/or orthodontics.

Complex customised implants may now be rapidly manufactured at much reduced cost using CAD/Metal technology in situations where CNC S-axis milling is not possible, e.g. with respect to complex 3-D geometry and the manufacture of thin veneers, which are difficult to raiJI without fracturing the ύiin veueer.

However the surface finish on such rapid manufactured products is currently of poor quality in comparison to that t»f computer numeriscd control 5 axis milling of a part and this makes the manufacture of precision attachments of titanium or other compatible materials difficult with respect to rapidly manufactured products. For example the locking taper system described by Bicon is not compatible with this rapid product manufacture as (he hole to receive the locking taper cannot be rapidly manufactured concomitantly with the rapid build of the surgical implant.

Similarly, the rapidly manufactured part caiuiot be designed and rapidly manufactured with incorporated abutment projections for the attachment of an additional part (e.g. a fixed, removable denial crowa / bridge or overdenlure / or other relevant system such as eye ear nose Hp digits limb etc) as the surface irregularities on the abutment related to the cooling of die surface layer of a rapid manufactured product, prevents finishing to the degree of tolerance of 5 avis milling e.g. that required for the provision of a friction grip retained I cold weld system of attachment.

The host implant cat* be made from particle fusion techniques of surgical pad© Material described in Rapid Product Manufacturing Technology (EBM SLS etc) or CNC milled from a block of implantable material.

Following any surface finishing (by sandblasting, surface etching, machining, electric discharge machining, hand finishing, or other suitable method etc) docking holes are drilled to receive a second part which is currently manufactured by 5 axis CNC milling technology.

Thus, according to a lϊrst aspect of the invention we provide a conjoined implant system comprising a fust component part which is a host implant provided with one or more (femaJe) docking holes; a second component part, which is a tenant implant provided with one or more (Female) docking holes; and a third component part comprising a bridging component provided with one or more (male) peg!' adapted to fit into the one or more docking holes of the first and the second component parts_* provided that the pegs and boles are tapered with respect to each other.

The one or more pegs provided on the third component part adapted, to fit into the one or more docking holes of the first component part are the host locking pegs. Whilst the one or more pegs provided on the third component part adapted to fit into the one or more clocking holes of the second component part are the tenant locking pegs. Thus, the host locking pegs and the tenant locking pegs may be the same or different. The host locking pegs and (lie tenant locking pegs may be contiguous or discontiguous. When the host locking peg is contiguous with the tenant locking taper the same peg may be used to conjoin the implant host and the tenant two coaxial docking holes as hereinbefore described to tbrm (he implant system of the invention. Alternatively, the host locking peg may be dύ&onfiguous with the tenant locking peg in the implant system of (he invention,

U will be understood by the person skilled in the art that the host and the tenant may comprise the same number of docking holes or the number may be different. Similarly, some of the host and locking pegs may me be contiguous, and some discontiguous or all of the pegs may be contiguous or all of the pegs may be discontiguous. In ixrder for a locking allacliment to occur there must be a tapered relationship between the (male) peg ami the corresponding (female) hole, it will be understood that the peg may be straight and tire hole tapered or the hole may be straight and the peg is tapered. The implant system of the invention may comprise a mixture wherein some of the (male) pegs arc straight and the corresponding (female) holes are tapered and the remainder of the (male) pegs arc tapered and lhe corresponding (female) holes are straight. Alternatively, aH of the (male) pegs are tapered and Uie corresponding (female) holes are straight or all of the (male) pegs are straight and the corresponding (female) holes are tapered. It is also within the scope of the invention for all of the host (male) pegs to be tapered and all of the tenant (male) pegs to be straight and the correspondin g (female) holes shaped accordingly.

However, in a particularly preferred embodiment of die invention all of the male pegs are tapered, that is, both the host and tenant pegs are tapered and aU corresponding (female) holes, that is, both the host and tenant holes are straight. The use male tapered pegs is advantageous in that, inter alia, it Tedυces any gap left between the peg and the inner surfaces of the and therefore minimises the risk of undesiraWe bacteria being harbowed which could, for example, produce a smell and cause bone resorption if bone is laid over the top of the iraplanl,

l he taper in each of the pegs or holes may be the same of different and niay vary depending upon, inter alia, the strength of the join that is desired or the ease of implantation, However, for the ease of manufacture it is preferred that each of the tapered pegs and or holes comprise substantially the same taper within manufacturing margins, The shape, particularly the longitudinal cross-sectional shape ύt^'iht pegs and the holes may vary, but is generally preferred that the cross-scctioiial shape of the pegs is smbstaniiaHy tho same as that of the holes, Thus, the cross-sectional shape of the pegs and the holes may be substantially symmetrical, i.e. it can have the same diameter from side to the other, The cross-sectional shape may be circular, oval, elliptical, kidney-shaped, triangular, quadrangular or polygonal,

The tapered peg or hole as hereinbefore described may comprise a straight, uniapered cylindrical section and a tapered section. However, preferably the tapered peg or hole is tapered along substantially the whole of its length.

The degree of taper on the peg or hole or (he tapered section of the peg or hole may vary, but will generally taper inwardly al an angle of from about 0.5 to 15 degrees relative to tile longitudinal axis of the peg or hole, preferably 0,3 to HO degrees, more preferably 1 to 5 degrees, more preferably I to 2 degrees, such as 1 ,5 degrees,

The peg or hole may optionally be provided with projections or protrusions constructed on its surface_* such as ridge-like projections, which comprise a pitch or depth of from about 0.2 to Imm, However, preferably ihe peg or hole is provided with a substantially smooth surface.

In a particularly preferred aspect of the invention, one or more of the holes ia the host or tenant is provided with a peripheral aperture or channel- The aperture or channel is desirably positioned at or adjacent the closed end of the hole and acts as a conduit for trapped air to be released. Thus, the use of the aperturcd hole is advantageous in that the air which would be compressed (luring the insertion of the peg may be released. Compression of air trapped in the hole can cause resistance to the insertion of the peg and thus the release of the air facilitates the ease of insertion of the peg. If an aperture or channel cannot be placed in one or more of the holes of the host or tetiant, then an alternative is to include an airspace void which can aid in "absorbing" the compression of the air.

In a particularly preferred aspect of tile invention the third component tenant part of the implant system comprises one or more dental crowns. Thus we provide an hnplant system wherein the tenant part is a dental crown

According to this aspect of the invention we provide an implant for fixing a dental prostheses, such as dental crowns_* bridges, dentures or the like, comprising a conjoined implant system comprising a first component part which is maxillary or mandibular implant provided with one or more (female) docking holes, a second component part which is a dental crowns,, bridges, dentures or the like, provided with one or more (female) docking holes; and a third component part comprising an abutment bridge provided with one or more (male) pegs adapted to fit into the one or more docking holes of (he first and the second component parts; provided that the pegs and holes are tapered with respect to each other,

IS According to this aspect of «be invention we particularly provide an implant system for fixing a dental prostheses, such as dental crowns, bridges, dentures or the like, wherein the first component part (host) is a facial maxillary or mandibular implant

A first host component as hereinbefore described is novel per χc_t particularly when the first component is a maxillary or mandibular implant provided with one or more (female) docking holes as hereinbefore described.

Thus as according to this aspect of the invention \w provide a maxillary or mandibular implant provided with one or more (female) docking holes, particularly tapered docking holes as hereinbefore described.

In use, the host implant, may be positioned and fixed using conventional tecJiniques known per .¥«. Thus, the host implant may be fixed using conventional anchors, such as, fasteners, pins, nails, screws, suture anchors, etc.

In addition, a second component part of the implant system as hereinbefore described is novel per se, ThuSi the second component part will generally comprise an abutment bridge comprising one or (male) locking pega to fit into the (female) docking holes. As described herein the (male) locking pegs are preferably tapered. Several individual pegs may be used as individual abutment bridges or joined in series by a bar onto which is located multiple locking taper pegs. In particular, the abutment bridge according to this aspect of the invention comprises a bar onto which are located multiple locking pv&s, e.g. tapered pegs. According to this aspect of the invention a second component part, which will generally comprise an abutment bridge comprising one or more (male) locking pegs to fit into the one or more (female) docking holes In particular, the abutment bridge according to this aspect of the invention comprises a bar onto which are located multiple locking pegs, eg. tapered pegs.

According to a yet further aspect of the invention we provide a kit for attaching or inserting a conjoined implant system as hereinbefore described which comprises a first component part which is a host tmplajit provided with onq or more (female) docking holes: a second component part which is a tenam implant provided with one or more (female) docking holes; and a third component p<u1 comprising a bridging component provided with one or more (male) pegs adapted to fit into the one or more docking holes of the first and the second component parts: provided that the pegs and hobs are tapered with respect to each other.

The kit according to this application may optionally include one or more fixation tools When the implant system of the invention is an iinpi-utt for fixing a dental prostheses, such as dental crowns, bridges, dentures or the like, the kit may also optionally include oue or more of a maxillary or mandibular implant, oue or more dental crowns, bridges, dentures or the like, and an abutinenl bridge as hereinbefore described.

According to a y«t further aspect of the invention we provide a method of making an implant system or any of the aforementioned component parts which comprises tbe step of designing and positioning the docking holes and/or the pegs using CAD CAM technology, According to this aspect of the invention, we particularly provided a method of making an implant host, such as a maxillary or mandibular implant, provided with one or nαore (female) docking holes, particularly tøpeied docking holes as hereinbefore described.

According to a further aspect of the invention we provide a me(hod of treating damaged, diseased or missing body parts which comprises excising damaged and/or diseased body parts and selected adjacent parts, and replacing excised and/or missing parts by the insertion of an implant syslem as hereinbefore described,

The host implant is the foundation component on which the conjoined implant system of the present invention is built.

The host implant can be made from particle fusion techniques of surgical grade material described in Rapid Product Manufacturing Technology (EBM SLS etc) or CNC milled from a block of implantable material.

Following any surface finishing (by sandblasting, surface etching, machining, eiectπc discharge machining, hand finishing), or other suitable method etc) docking holes are drilled to receive a second part which is currently manufactured by 5 axis CNC milling technology. A second part ^■•- the abutment bridge - is manufactured with a (male) locking taper peg to fit iuto the (female) docking holes. Several individual pegs may be used as individual abutment bridges or joined in scries by a bar onto which are located multiple locking taper pegs.

S The path of insertion of the pegs into the docking holes is crucial and designed / calculated with CAD CAM technology.

The abutment bridge component has a second set of locking taper pegs to fit ioto female docking holes of a third component part » the tenant. Thy tenant locking peg may be contiguous with the 10 locking taper peg in the Host docking hole i.e. the same peg is used to conjoin the implant across two adjac<?nt docking holes - or the tenant locking pegs may be located at some point on a bar connecting several host locking taper pegs, in a position thai is unrelnted to the host locking taper pag system. S The abutment bridge therefore bridges the junction between two or more individual implant components of a conjoined implant system.

Applications of the tenant component

The tenant component may be aa epithesis i.e. an implant that is exposud to the air either through lό the oixmasal cavity or external skin e.g. m the reconstruction of tbc paiate, eye nose lip ear digit or limb.

20 Jn dentistry, the tenant component may take the form of a dental crown or bridge or denture or obturator which is tapped onto the tenant locking peg which is acting as a dental abutment.

The angle of taper on the locking taper peg is preferably set at. 1.5 degrees

The width of the docking hole and width of taper is determined by the anatomical region type of implant and physical loading of the implant system.

If prevention of rotation is critical the docking hole and locking inpat peg can be made elliptical in cross scctioa.

Thus impiant parts may be joined together without the use of screws, or cement and without recourse Io more expensive and complex technological methods of fksing titanium and other parts together.

The cold welded implant system may l)e removed / dismantled by tapping the system on and off the point of anchorage. This permits simple revision of the implant system in the case of implant failure or as a consequence of personal injury.

The concept of using the locking taper system for conjoining customized implant components to facilitate the surgical placement of implants with less major surgery is novel and a new concept. Some implants may bo very difficult to place with the surgical access that is available, and a conjoined implant system will facilitate operative surgery particularly in cases where access to the anatomical area is a problem. The invention will facilitate the delivery of surgery with reduced operative trauma, reduced dependency on hospital resources through shortened surgical procedures and reduce the dependency on critical esire facilities, Recovery will be ttϊhanced with shorter hospital stays, making day case surgery feasible,

The fitting of a denial crown (female component) onto a projecting (male) abutment is a new concept and has applications across the breadth of restorative and implant dentistry and surgery in general.

The system cotild be used in - but is not limited to:

Restorative Dentistry - as a means to secure dental crown units / bridgcwork to fabricated posts and abutments in natural teeth without the use of cement or chemical bonding. The system would be especially useful in teeth that have undergone root canal therapy.

Dental Implants - As a means to secure dental crown uoits to eudo-osseωis aiid sutφeriosteal dental implant abutments and associated superstructures without the use of screw systems, cementation or chemical surface adhesive bonding.

Surgical Implants iα General - As a means to secure hybrid titanium and or other ύwplantabte materials together in surgical implant systems - particularly in the attachment of digits and artificial limbs to the skeleton and in the attachment of removable joint surface Vϋtteets.

As a means to attach abutments wit)) precision attachments for fixed and removable epilheses

22 Use of Implant System in Conjunction with Tissue Engineering Techniques

The implant system may be used in conjunction with guided bone regeneration systems for υμiimizatiøπ of gingival eraαgence profile.

5 ft is also proposed to use bane regeneration techniques in particular with implants having a large surface arøa that must be covered by vital tissue. Wc propose to use Bone Morphogenetic Protein and in particular but not exclusively the Infuse System®. This will assist in the provision of additional stability to the conjoined implants in that the formation of a bony veneer iύ on the surface of the implant will reinforce the fusion of the individual implant components provided by the locking iapered pegs.

The formation of vascular bone deep to the overlying tissues will also assist in creating and maintaining a new blood supply from (he deep surface to the overlying tissues and skin. This 5 will help to prevent long term fenestration of the implant system through ϋxt skiπ₅ which otherwise would only receive a blood supply based on a circumferential from the peripheral tissues.

Detailed Description of the Invention

2σ TIwj invention will now be described by way of example only and with reference to the accompanying drawings in which;

Figure 1 is a repteseutation of a Host Implant with docking holes; Figure 2 is representation of an Abutment Bridge; and

23 Figure 3 is representation of the assembled Conjoined Implant System.

Referring the aforementioned figures; the tenant components are individual dental crowns and a shoulder is present for an end point of crown seating. Escape channels are incoiporatcd in the design for lhc escape of air when scaling the tenant female part (dental crown)

Aii airspace void/escapϋ channels are incorporated into die docking hole in the Host Component to decompress the area during placement.

Referring Io figure 3; in a hemifacial reconstruction, Infuse bone graft, is used to cover the implant with a bony veneer and to produce an epithelial cuff and gingival attachment around the necks of the teeth

24

Claims

1. A conjoined implant system comprising a first component part which is a hosi implant provided wilh one or more (female) docking holes; a second component part which is a tenant implant provided with one or more (female) docking holes; and a third component part comprising a bridging component provided with one or moie (malo) pegs adapted to Fit iuto the one or more docking holes of the first and the second component parts; provided that the pegs and holes are tapered wiύi respect to each other.

2. A conjoined implant system according to claim t wherein the host locking pegs and the tenant locking pegs are contiguous.

3. A conjoined implant system according to claim 1 wherein all of the (male) pegs are tapered and the corresponding (female) holes arc straight.

4. A conjoined implant system according to claim 3 wherein each of the tapered pegs and or holes comprise substantially the amaa taper witJώi manufacturing margins.

5. A Conjoined implant system according to claim I wherein the longitudinal cross-sectional shape oftbe pϋgs is substantially the same as that of the holes.

25

6. A conjoined implant system according to claim 1 wherein the tapered peg or hole is tapered along substantially the whole of its length.

7. Λ conjoined implant system according to claim 1 wherein the degree of taper on the peg or hole or the tapered, section of the peg or bole is an angle of from about 0.5 to 15 degrees relative to the longitudinal axis of the peg or hole.

8. A conjoined implant system according to claim 1 wherein one or more of the holes in the host or tenant is provided with a peripheral aperture or channel.

9. A conjoined implant system according to claim 1 wherein the tenant pait is a dental crcπvn

10. An implanl for fixing, a denial prosthesis comprising a conjoined implant system comprising a first component part which is maxillary or mandibular implant provided with one or more (female) docking holes; a second coaipomnt part which is a dental crowns, bridges, dentures or the like, provided with one or moie (female) docking holes; and a third component part comprising an abutment bridge provided with one ox more (male) pep adapted to fit into the orκ? or more docking holes of the first and the second component parts; provided that the pegs and holes are tapered with respect to each other,

26

11. AH implant according to claim 10 wherein tine first component part (host) is a facial maxillary or mandibular implant.

12. A maxillary or mandibular implant provided with one or more (female) docking holes, particularly tapered docking holes as hereinbefore described.

13. A tenant implant comprising an abutment bridgw comprising, one or more (mate) locking pegs to fit into the one or more (female) dockiαg holes.

14. A kit for attaching or inserting a conjoined implant system as hereinbefore described which comprises; a fjirst component part which is as host implant provided Λvith one or more (femaJe) docking holes; a second component part which is a tenant impJanf provided with one or more (female) docking holes; and a third component part comprising a bridging component provided with one or more (male) pegs adapted to fit into the one or more docking holes of the first sand the second component pans; provided that the pegs and holes are tapered with respect to each other.

15, A kit according Jo cJaim 14 wherein the kit includes one or more fixation tools.

l ^ή, Λ kit according to claim 14 wherein the iinplaut system is an implant for fixing a dental prostheses and Oie kit include one or more of a maxillary or mandibular implant one or more dental crowns, bridges, dentures or the like, and an abutment bridge.

27

17. A method of waking an implant system according to claim 1» or any of ils component parts, which comprises the step of designing and positioning the docking holes and/or the pegs using CAi> CAM technology.

18. Λ method of making an implant host, such as a maxillary or mandibular implant, provided witli on« or more (female) docking holes.

Ϊ9. A method of making an implant host according to claim 19 wherein the one or more (female) docking holes me tapered docking holes.

20. A method of treating damaged, diseased or missing body parts which comprises excising damaged and/or diseased body parts and selected adjacent parts, and replacing excised and/or missing part- by the insertion of an implant system according Io eiaim I .

21. A conjoined implant system, an implant, a kit or a method substantially as hereinbefore described with reference to the accompanying examples and drawings.

2S