Dental pin, dental pin handpiece and method

Abstract

A combination handpiece and dental pin to be cemented into a receiving hole in a tooth, said handpiece comprising an elongate body having a longitudinal body axis and supporting a handle and a head. The dental pin comprises an implantable body for implantation into the tooth the implantable body having an elongate insertion portion at a distal end thereof. The elongate insertion portion defines a dental pin insertion axis, and an exposed portion to extend from the hole and form a framework for a curable restorative material for restoring a portion of said tooth. The dental pin further comprises an attachment portion at a proximal end connecting said implantable body to said head of said handpiece, and a releasable connection allowing for selective detachment of the implantable body from the handpiece. There is also provided a dental method for preparing a tooth to receive a curable restorative material for restoring a portion of said tooth, said method including the steps of preparing the tooth to provide a receiving surface for receiving the curable restorative material; drilling a plurality of receiving holes into the tooth at the receiving surface; providing a plurality of dental pins each dental pin attached to a respective handpiece and including a distal end and a dental pin insertion axis; injecting a settable cement into each hole of the plurality of holes manipulating each handpiece to insert the respective distal end and an elongate insertion portion of one of a respective dental pin of said a plurality of dental pins into each hole; and detaching each handpiece from the respective dental pin so that a portion of each dental pin extends from the respective hole.

Description

DENTAL PIN, DENTAL PIN HANDPIECE AND METHODField

[0001] The invention relates to dental pins, which were once commonly used in restorative dentistry to provide additional support and retention for dental crowns and other restorations.Background

[0002] Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

[0003] Dental pins are known and used in restorative dentistry to provide additional support and retention for dental crowns and other restorations. Initially dental pins were cemented into the tooth in predrilled holes intended to receive the pin. However cementing of the pins proved to be fiddly and time consuming partially due to the need to set multiple pins in place at small spacings (<2mm) prior to cement curing.

[0004] The use of cemented dental pins gave way to the rise of the simpler and easier selfthreading system, in which a self-threading pin was screwed into the hole thereby obviating the need for cement. The threaded pin includes a weakened portion intended to shear off when the screw end of the pin hit the bottom of the hole, leaving 2 to 3 mm of remaining pin above the tooth to engage the restorative material. The self-threading system largely replace the use of cemented pins. However, a major problem became evident since the outwards stress induced by the self-threading pin as it cut into the hole wall induced a localised stress on the tooth which can lead to eventual cracking of the dentine and failure of the bond. In addition, the threaded bond may allow the ingress of bacteria and in some cases causing pulpitis and loss of fixation to the tooth.

[0005] As a result, the use of self threading or self tapping pins has been replaced in many situations, by crowns, slots and grooves, and also by implants which require a significantly more invasive procedure whereby the tooth is fully extracted and replaced with an implant screwed into the bone of the jaw and used as a foundation for a bridge, crown or dentureAH25(45567071_l):SCP

[0006] Given the complexities and cost of installing implants, they were initially used in hyper obvious situations such as filling a missing tooth or where a tooth had to be extracted due because of massive and obvious trauma or untreatable vertical root fracture. However, following initial success in these applications overtime implants have progressively been used in more and more situations particularly where restorations are seen to be somewhat risky or difficult, thereby lowering the threshold for tooth extraction.

[0007] Nowadays however, after several decades of significant clinical experience it has become evident that implants also have failings including installation problems such as risk of infection, nerve damage, sinus problems and injury or damage to surrounding teeth or blood vessels during the procedure. Furthermore, longer term issues are becoming evident such as peri-implantitis (a slowly destructive infection around the implant which has proven to be difficult if not impossible to stop). Initial expectations of implants being far superior to natural teeth have faded. It is now estimated that as much as 45% of implants fail and / or become infected with peri-implantitis within a few years of placement - much higher than previously thought.

[0008] Accordingly, some experts believe that all steps should be taken to preserve the natural tooth and restore the natural tooth and that the tooth should only be extracted in extreme circumstances and as a last resort

[0009] It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.Summary of Invention

[0010] In a first aspect, the invention provides a combination handpiece and dental pin to be cemented into a receiving hole in a tooth, said handpiece comprising:an elongate body having a longitudinal body axis and supporting a handle and a head; andwherein said dental pin comprises:an implantable body for implantation into the tooth said implantable body having an elongate insertion portion at a distal end thereof, said elongate insertion portion defining a dental pin insertion axis, and an exposed portion to extend from the hole and form a framework for a curable restorative material for restoring a portion of said tooth; andAH25(45567071_l):SCPan attachment portion at a proximal end connecting said implantable body to said head of said handpiece, anda releasable connection allowing for selective detachment of the implantable body from the handpiece;wherein the dental pin insertion axis of said respective dental pin attached to said handpiece is inclined by an offset angle to the longitudinal body axis..

[0011] Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

[0012] Preferably, the offset angle is between 45° and 85°, preferably between 66° and 76° and most preferably around 71°.

[0013] Preferably, the offset angle is ± 10°, more preferably ± 5°, of an angle between a rotation axis of a drill hand piece used to drill the plurality of receiving holes into the tooth and a respective hand grip axis of the handpiece.

[0014] Preferably, the attachment portion is fixedly attached to said head of the handpiece.

[0015] Preferably, the attachment portion is at least partially embedded in the head of the handpiece.

[0016] Preferably, each handpiece is overmolded about the attachment portion to provide a unitary handpiece and dental pin.

[0017] Preferably, the attachment portion is configured for selectively releasable attachment to said head of the handpiece.

[0018] Preferably, the releasable connection includes a frangible join configured to preferentially fail upon application of a fracture force thereby providing selective detachment of the implantable body from the handpiece.AH25(45567071_l):SCP

[0019] Preferably, the preceding claims wherein the attachment portion and the head include complementary connection formations providing selective attachment and release of the dental pin to the handpiece.

[0020] Preferably, the complementary connection formations are configured for friction fit connection.

[0021] Preferably, each handpiece is formed of a plastics material.

[0022] Preferably the implantable body includes a pre formed angulation between the elongate insertion portion and the exposed portion.

[0023] Preferably the elongate insertion portion is angularly offset from the exposed portion by an angle between 10° and 80° preferably between about 25° to about 40° and most preferably around 35°.

[0024] Preferably the elongate insertion portion is axially aligned with the attachment portion such that the pin includes a return length defining a dogleg geometry.

[0025] In a second aspect, the invention provides a handpiece for use in combination with a dental pin to be cemented into a receiving hole in a tooth, said handpiece comprising:an elongate body having a longitudinal body axis and supporting a handle and a head; andwherein said dental pin comprises:an implantable body for implantation into the tooth said implantable body having an elongate insertion portion at a distal end thereof, said elongate insertion portion defining a dental pin insertion axis, and an exposed portion to extend from the hole and form a framework for a curable restorative material for restoring a portion of said tooth; andan attachment portion at a proximal end connecting said implantable body to said head of said handpiece, anda releasable connection allowing for selective detachment of the implantable body from the handpiece.

[0026] In a third aspect, the invention provides a dental pin to be cemented into a receiving hole in a tooth, said dental pin comprises:AH25(45567071_l):SCPan implantable body for implantation into the tooth said implantable body having an elongate insertion portion at a distal end thereof, said elongate insertion portion defining a dental pin insertion axis, and an exposed portion to extend from the hole and form a framework for a curable restorative material for restoring a portion of said tooth; andan attachment portion at a proximal end connecting said implantable body a handpiece, anda releasable connection allowing for selective detachment of the implantable body from the handpiece;wherein said handpiece comprises an elongate body having a longitudinal body axis and supporting a handle and a head.

[0027] In another aspect, the invention provides a dental method for preparing a tooth to receive a curable restorative material for restoring a portion of said tooth, said method including the steps of:(A) preparing the tooth to provide a receiving surface for receiving the curable restorative material;(B) drilling a plurality of receiving holes into the tooth at the receiving surface;(C) providing a plurality of dental pins each dental pin attached to a respective handpiece and including a distal end and a dental pin insertion axis;(D) injecting a settable cement into each hole of the plurality of holes(E) manipulating each handpiece to insert the respective distal end and an respective elongate insertion portion of one of a respective dental pin of said a plurality of dental pins into each hole; and(F) detaching each handpiece from the respective dental pin so that a portion of each dental pin extends from the respective hole.

[0028] Preferably, each receiving hole is drilled to have a diameter larger than a maximum lateral width of the respective insertion portion to be inserted into the hole.

[0029] Preferably, each receiving hole is drilled and each respective dental pin is sized to provide a surrounding clearance of between 10 and 90 microns and more preferably around 35 microns (0.035mm).AH25(45567071_l):SCP

[0030] Preferably, each hole is drilled adjacent a periphery of said receiving surface of said tooth.

[0031] Advantageously, preferred embodiments of the invention may enable stronger retention of the composite restoration or core material to the tooth structure in a pain-free, leak free , caries-free way, and assists in preserving the integrity of any bonding agents employed by augmenting them with substantial mechanical retention to prevent destructive micro movement from stress cycling progressively breaking the bond and causing leakage pain decay and eventually loss of the restorative material.

[0032] Advantageously, preferred embodiments of the invention may removes the problem of micro cracking the tooth as caused by stress-inducing self tapping, self-threading pins.

[0033] Advantageously, preferred embodiments of the invention may allow many more pins to be placed without creating a continuous line of dangerously accumulating stress - allowing the pins to be placed in their ideal position 1 mm from the periphery in a circular line which would ordinarily cause a stress concentration and aggregate individual pin stress in the same line which could cause a large amount of dentine to crack, as used in rock breaking techniques, as seen in the images below

[0034] It will be appreciated that in contrast to dental posts, which are placed in the centre of the tooth in the space previously occupied by the pulp (nerve) , and which exert an outwards splitting action when lateral chewing forces are applied to them , and are renowned for causing vertical root fractures, pins virtually never cause a catastrophic vertical root fracture , and they are placed around the periphery of the tooth which advantageously gives the greatest resistance to rocking and lateral forces induced by chewing, and this high density pin technique works so well it avoids any need to electively devitalise the tooth to provide post space, which causes it to become dry and brittle and causes a dramatic increase in catastrophic vertical root fracture and loss of the tooth, recurring further expensive and problematic treatments such as bridges dentures and implants.AH25(45567071_l):SCPBrief Description of Drawings

[0035] The invention will be more clearly understood from the following description of an embodiment thereof, given by way of example only, with reference to the accompanying drawings, in which: -

[0036] Fig 1 A is a schematic plan view of a tooth having an area to be restored;

[0037] Fig IB is a schematic plan view of the tooth of Fig 1A having an array of holes drilled around a circumference of the area to be restored;

[0038] Fig 1C is a schematic plan view of the tooth of Fig IB displaying the step of injecting a curable cement into one of the holes;

[0039] Fig ID(i) & ID(ii) are schematic perspective views of the tooth of Fig 1C showing the step of inserting a pin into one of the holes;

[0040] Fig IE is a schematic perspective view showing the tooth once pins have been inserted into each hole;

[0041] Fig IF is a schematic perspective view showing the tooth showing the pins bent toward the centre of the tooth away from the tooth outer circumference;

[0042] Fig 2A is a schematic longitudinal cross section of a dental pin having a pin part and a handpiece in accordance with the invention;

[0043] Fig 2B is a schematic longitudinal cross section of the dental pin shown in Fig 2A wherein a force is applied to the hand piece to fracture the pin at the frangible join;

[0044] Fig 2C is a schematic longitudinal cross section of the dental pin shown in Fig 2A wherein the pin and the hand piece are detached;

[0045] Fig 3 A is an exploded schematic longitudinal cross section of a dental pin having an attachable pin part and a handpiece for receiving the pin part in accordance with another embodiment of the invention;AH25(45567071_l):SCP

[0046] Fig 3B is a schematic longitudinal cross section of the dental pin shown in Fig 3 A wherein the pin part is attached to the handpiece;

[0047] Fig 3C is a schematic longitudinal cross section of the dental pin shown in Fig 3A wherein the pin is fractured at the frangible join so that an implantable body of the pin part is detached and an attachment portion of the pin part is connected to the handpiece;

[0048] Fig 3D is a schematic longitudinal cross section of the dental pin shown in Fig 3 A wherein the remaining attachment portion of the pin part is separated from the handpiece;

[0049] Fig 4A is an exploded schematic longitudinal cross section of a dental pin having an attachable pin part and a handpiece for receiving the pin part in accordance with another embodiment of the invention;

[0050] Fig 4B is a schematic longitudinal cross section of the dental pin shown in Fig 4A wherein the pin part is attached to the handpiece;

[0051] Fig 4C is a schematic longitudinal cross section of the dental pin shown in Fig 4A wherein the pin is fractured at the frangible join so that an implantable body of the pin part is detached and an attachment portion of the pin part is connected to the handpiece;

[0052] Fig 4D is a schematic longitudinal cross section of the dental pin shown in Fig 4A wherein the remaining attachment portion of the pin part is separated from the handpiece;

[0053] Fig 5A is an exploded schematic longitudinal cross section of a dental pin having an attachable pin part and a handpiece for receiving the pin part in accordance with another embodiment of the invention;

[0054] Fig 5B is a schematic longitudinal cross section of the dental pin shown in Fig 5A wherein the pin part is attached to the handpiece;

[0055] Fig 5C is a schematic longitudinal cross section of the dental pin shown in Fig 5A wherein the pin part is separated from the handpiece;AH25(45567071_l):SCP

[0056] Fig 6A is perspective view of a dental pin having an integral pin part and a handpiece in accordance with another embodiment of the invention;

[0057] Fig 6B is front view of the dental pin shown in Fig 6A;

[0058] Fig 6C is a top view of the dental pin shown in Fig 6A;

[0059] Fig 6D is a cross-section view of the dental pin shown in Fig. 6A taken along section plane A-A of Fig. 6C;

[0060] Fig 6E is detail view B of the dental pin shown in Fig 6A;

[0061] Fig 7A is perspective view of a handpiece for receiving a connectable dental pin in accordance with another embodiment of the invention;

[0062] Fig 7B is front view of the handpiece shown in Fig 7A;

[0063] Fig 7C is a top view of the handpiece shown in Fig 7A;

[0064] Fig 7D is a cross-section view of the handpiece shown in Fig. 7A taken along section plane C-C of Fig. 7C;

[0065] Fig 7E is detail view D of the handpiece shown in Fig 7D;

[0066] Fig 7F is an exploded perspective view of the handpiece of Fig. 7A and an associated connectable dental pin;

[0067] Fig 7G is detail cross section view of the dental pin and handpiece shown in Fig 7F with the pin connected to the handpiece;

[0068] Fig 8A is perspective view of a handpiece for receiving a connectable dental pin in accordance with another embodiment of the invention;

[0069] Fig 8B is front view of the handpiece shown in Fig 8A;

[0070] Fig 8C is a top view of the handpiece shown in Fig 8A;AH25(45567071_l):SCP

[0071] Fig 8D is a cross-section view of the handpiece shown in Fig. 8 A taken along section plane E-E of Fig. 8C;

[0072] Fig 8E is detail view F of the handpiece shown in Fig 8C;

[0073] Fig 8F is detail view G of the handpiece shown in Fig 8D;

[0074] Fig 9A is perspective view of a connectable dental pin for connection to the handpiece shown in Fig 8A;

[0075] Fig 9B is front view of the dental pin shown in Fig 9A;

[0076] Fig 9C is a top view of the dental pin shown in Fig 9A;

[0077] Fig 9D is a cross-section view of the dental pin shown in Fig. 9A taken along section plane H-H of Fig. 9B;

[0078] Fig 10A is an exploded perspective view of the handpiece of Fig. 8 A and dental pin of Fig 9A;

[0079] Fig 10B is an assembled front view of the handpiece of Fig. 8 A and dental pin of Fig 9A;

[0080] Fig 10C is a top view of Fig 10B;

[0081] Fig 10D is a cross-section view of Fig. 10B taken along section plane I-I of Fig. 10C;

[0082] Fig 10E is detail view J of Fig 10A;

[0083] Fig 11 A is front view of a further embodiment of a connectable dental pin for connection to the handpiece shown in Fig 8A;

[0084] Fig 1 IB is side view of the dental pin shown in Fig 11 A

[0085] Fig 11C is a cross-section view of the dental pin shown in Fig. 11 A taken along section plane K-K of Fig. 1 IB;AH25(45567071_l):SCP

[0086] Fig 1 ID is a detail view L of the dental pin shown in Fig 11 A;

[0087] Fig 12A is front view of a dental pin having an integral pin part and a handpiece in accordance with another embodiment of the invention;

[0088] Fig 12B is top view of the dental pin shown in Fig 12A;

[0089] Fig 12C is a cross-section view of the dental pin shown in Fig. 12A taken along section plane N-N of Fig. 12B;

[0090] Fig 13 A is an exploded perspective view of a handpiece and dental pin in accordance with another embodiment of the invention;

[0091] Fig 13B is an assembled top view of the handpiece and dental pin of Fig 13 A;

[0092] Fig 13C is a cross-section front view of Fig. 13B taken along section plane O-O;

[0093] Fig 13D is detail view P of Fig 13C;

[0094] Fig 14A is a perspective view of dentin pin holder in accordance with another aspect of the invention;

[0095] Fig 14B is a perspective view of a handpiece to be received in the holder shown in Fig.14 A;

[0096] Fig 14C is a perspective view of another handpiece to be received in the holder shown in Fig. 14A;

[0097] Fig 15 is a perspective view of the holder shown in Fig. 14A and an array of dental pin handpieces each carried in a holder;

[0098] Fig 16A is a perspective view of the handpiece of Fig. 8 A and dental pin of Fig 9A held in a holder in accordance with another aspect of the invention;

[0099] Fig 16B is a perspective exploded view of the handpiece and dental pin and holder of Fig. 14A;AH25(45567071_l):SCP

[0100] Fig 17A is a perspective view of an array of dental pins having an integral pin part and a handpiece each carried in a holder in accordance with another aspect of the invention;

[0101] Fig 17B is a side view of the handpiece and dental pin and holder of Fig. 15 A;

[0102] Figs 18A &18B show respective perspective and front views of an implantable body portion of a pin including a frangible join displaying a surface pattern in accordance with an embodiment of the invention;

[0103] Figs 18A &18B show respective perspective and front views of an implantable body portion of a pin including a frangible join displaying a surface pattern in accordance with an embodiment of the invention;

[0104] Figs 19A &19B show respective perspective and front views of an implantable body portion of a pin including a frangible join displaying a surface pattern in accordance with another embodiment of the invention;

[0105] Figs 20A & 20B show respective perspective and front views of an implantable body portion of a pin including a frangible join displaying a surface pattern in accordance with another embodiment of the invention;

[0106] Figs 21 A & 21B show respective perspective and front views of an implantable body portion of a pin including a frangible join displaying a surface pattern in accordance with another embodiment of the invention;

[0107] Figs 22A & 22B show respective perspective and front views of an implantable body portion of a pin including a frangible join displaying a surface pattern in accordance with another embodiment of the invention;

[0108] Figs 23 A & 23B show respective perspective and front views of an implantable body portion of a pin including a frangible join displaying a surface pattern in accordance with another embodiment of the invention;AH25(45567071_l):SCP

[0109] Figs 24A & 24B show respective perspective and front views of an implantable body portion of a pin including a frangible join displaying a surface pattern in accordance with another embodiment of the invention;

[0110] Figs 25 A & 25B show respective perspective and front views of an implantable body portion of a pin including a frangible join displaying a surface pattern in accordance with another embodiment of the invention; and

[0111] Fig 26 shows a schematic view of a dental hand piece.Description of Embodiments

[0112] One method of the invention will now be described.

[0113] First, with reference to Fig. 1 A, the tooth 1 is prepared to provide a receiving surface 2 for receiving the curable restorative material. This may include removal of undesirable tooth material to provide a surface 2 for bonding to the curable material. By way of example, in Fig.1 A, a lateral portion 3 of the tooth material is retained adjacent a volume to be filled 4 by the curable restorative material.

[0114] Advantageously, the pins are to be bonded into the tooth around the periphery of the receiving surface 2 adjacent the tooth side and into the dentin as seen in Fig. IB. Thus the pins may be referred to herein as ‘dentin (dentine)’ or ‘parapulpal’ pins since generally they are intended to be received into holes drilled into the dentin of the tooth adjacent to the pulp (parapulpal) rather than traditional posts which are typically installed into the area occupied by the pulp also known as the root canal.

[0115] The size, shape, diameter and spacing of the dental pins is selected dependent on the parameters of the tooth, restoration and receiving surface while achieving maximum retention. Typically, the pins will have a maximum transverse width or diameter ranging between 0.3 and 1.0 mm, preferably between. 0.4 mm and 0.7mm and more preferably around 0.5 mm.

[0116] Hole diameter is preferably selected to be greater than the diameter of the respective pin, that is to say, the largest diameter or maximum transverse width of the pin portion to be inserted into the respective hole - which provides a surrounding clearance or spacing between the pinAH25(45567071_l):SCPwall and the hole wall. Preferably the hole and pin are selected to provide a surrounding clearance between the pin wall and the hole wall of between 10 and 100 microns, preferably 20 - 50 microns and more preferably around 35 microns (0.035mm) to ensure a minimum film thickness of cement and to allow adequate flow of viscous cement without causing excessive hydraulic back-pressure. Accordingly, the hole diameter may range between around 0.32 mm and 1.2 mm and preferably around 0.5mm to 0.8mm. By way of example, a pin having a maximum diameter of 0.5 mm would require a hole to be drilled in the tooth of diameter of around 0.57 mm thereby providing a surrounding clearance for cement of around 35 microns.

[0117] Advantageously by having a smaller diameter than the respective receiving hole, the cemented pins of the invention require comparative limited or no expansive loading within each hole for pin retention when compared to threaded pins which rely on mechanical interference engagement with the tooth material promoting internal stress within the tooth. Accordingly, the dentin pin and method of the invention is less likely to cause a fracture line between holes or micro cracking of the tooth which may allow dangerous long term leakage of bacteria into the dental nerve or pulp. Accordingly, the invention advantageously allows for the pins to be inserted at a closer spacing and at a higher number than might be advisable with threaded pins thus achieving strength and retention of the overlying core, crown or filling without cracking the tooth and risking pulpal death and thus allowing restoration of severely broken down tooth with resorting to extraction or implants. In addition, having a hole of a larger diameter than the respective pin diameter provides a space to allow for a predetermined minimum film thickness of cement between the pin and hole wall for retention. The spacing further allows for passage of the unset cement injected into the hole along the pin during insertion of the pin into the hole. That is to say, as the pin is inserted into the hole, the cement is displaced by the pin to flow between the hole wall and pin toward the hole entrance.

[0118] Precise initial placement assists in allowing a greater number of pins increasing stress dispersal and therefore the overall strength of the restoration. Accordingly, based on the pin size and spacing, preferably, indentations are made in the receiving surface 2 to be subsequently used as starter points for each subsequent pin hole 5 preferably by means of a high-speed needle point or round point diamond or tungsten carbide bur in a dental handpiece. For instance, starter indentations may be at approximately 1.6 mm between centres for a 0.675 mm diameter drill or approximately 1.2 mm between centres for a 0.57 mm diameter drill. Advantageously, use of aAH25(45567071_l):SCPhigh speed drill, at 500- 300,000 rpm allows more accurate commencement positions than a slow speed twist drill to start since it is less inclined to to chatter or move on the tooth.

[0119] Having marked the intended hole positions, the number of intended holes is noted.Typically for large restorations, 4 or more holes / pins are used, however, more may be used. For instance, restoration of a large MODL composite may require 10 or more pins / holes while the restoration of a large flat molar may require in the range of 4-20. This is in contrast to dental posts that occupy the pulpal space which is typically one post per tooth and never more than four per tooth and then only on a molar. For smaller restorations, less than 4 pins may be adequate and desirable.

[0120] Based on the number of holes intended to be drilled, an equivalent number of dentin pins are provided wherein each dentin pin is attached to a respective handpiece. The dentin pins may take a variety of forms, some of which require assembly with the handpiece and some of which include an integrated handpiece.

[0121] Fig 2A for example, shows schematic longitudinal cross section of a combination handpiece and dental pin 10 having a dental pin 12 and a handpiece 50 in accordance with an aspect of the invention. The dental pin 12 includes an implantable body 20 comprising a distal end 22 having an elongate insertion portion 24 defining a dental pin insertion axis Z and an exposed portion 26 which in this embodiment is also elongate and extends along the insertion axis Z as a continuation of the insertion portion 24. In some embodiments, such as this one, the implantable body 20 extends to an integral attachment portion 30 for attaching the pin 12 to the handpiece 50 and which is connected to the exposed portion 26 of the implantable body 20 by a frangible join 34 configured to preferentially fail upon application of a bending moment thereby detaching the implantable body 20 of the dental pin 10 from the attachment portion 30 and handpiece 50. In other embodiments as will be seen, the exposed portion also serves as an attachment portion.

[0122] In use the distal end 22 and insertion portion 24 are to be inserted into a hole 5 drilled into the tooth and fixed with a dental cement while the exposed portion 26 extends from the respective hole in the tooth to be used as a framework and anchor for the curable restorative material. Demarcation between the insertion portion 24 and the exposed portion 26 is not fixed and will depend on the hole depth and the depth the pin is inserted into the hole. Typically,AH25(45567071_l):SCPhowever, the hole is drilled to a predetermined depth and the pin selected to provide a predetermined length of insertion and a predetermined length of the exposed portion.

[0123] The implantable body 20 is typically of a circular cross section providing for cylindrical insertion 24 and exposed portions 26. Areas of an external surface 32 of the insertion portion 24 are textured or roughened, or include laterally extending formations in the form of protrusions or cavities to enhance mechanical bonding with the settable cement for bonding the pin into the respective hole in the tooth. Similarly, areas of an external surface 44 of the exposed portion 26 are textured or roughened, or include laterally extending formations in the form of protrusions or cavities to enhance mechanical bonding with the curable restorative material. The surfaces may be textured or roughened by a range of manufacturing processes including molding of the surface, lathe turning, sandblasting or grit-blasting, rolling, and acid or laser etching or laser micro-machining.

[0124] In some embodiments the formations take the form of circumferential ribs or as seen in the Figs. 2A-2C a helical thread. In some embodiments, areas of the external surface 32 of the insertion portion 24 and / or areas of the external surface 44 of the exposed portion 26 are textured with other patterns such as are exemplified in Figs 18A & 18B, 19A & 19B, 20A & 20B, 21 A & 21B, 22A & 22B, 23A & 23B, 24A & 24B and 25A & 25B.

[0125] Figs 18A &18B show respective perspective and front views of an implantable body 20 portion of the pin 12 including a frangible join 34 in accordance with an embodiment of the invention. The implantable body 20 includes indentations 45 in the form of ellipses or oval shapes extending circumferentially around the implantable portion of the pin. The indentations are intended to increase mechanical interlocking with the cement. Each indentation 45 is provided with a shallow curved bottom and sides to promote flow of cement into the indentation and reduce the chance of air entrapment or voids forming in the cement which may weaken the pull out strength and which will reduce chances of stress concentration and a crack developing if the pin is bent over after placement in the tooth as often occurs. The indentations of the embodiment shown in Figs 18A & 18B are arranged in axially aligned circumferentially extending arrays whereas the indentations of the embodiment shown in Figs 19A & 19B are arranged in axially offset circumferentially extending arrays.AH25(45567071_l):SCP

[0126] In other embodiments, such as that shown in Figs 20A & 20B the indentations are interlinked by axially extending grooves which form channels 46. These channels 46 facilitate improved cement flow during placement, by providing passageways between the indentations and allowing the luting material to propagate along the length of the hole / pin interface and more effectively fill the retention structures to further reduce the likelihood of air entrapment within the surface features and enhance the mechanical interlock between the pin and the surrounding cement.

[0127] Figs 21 A & 21B show respective perspective and front views of an implantable body 20 portion of the pin 12 including a frangible join 34 in accordance with another embodiment of the invention. In this embodiment the surface includes micro projections 47 extending outwardly from the surface.

[0128] Figs 22A & 22B show respective perspective and front views of an implantable body 20 portion of the pin 12 including a frangible join 34 in accordance with another embodiment of the invention. In this embodiment the surface includes a pattern of channels 48 extending outwardly around the circumference of the surface of the implantable portion linked by longitudinally extending grooves 49.

[0129] Figs 23A & 23B show similar, respective perspective and front views of an implantable body 20 portion of the pin 12 including a frangible join 34 in accordance with another embodiment of the invention. In this embodiment the indentations 45 are circular dimples provided with a shallow curved bottom and sides. In the alternative embodiment shown in Figs 24A & 24B the dimples are interlinked by axially extending grooves to form channels 46.

[0130] Figs 25A & 25B show similar, respective perspective and front views of an implantable body 20 portion of the pin 12 including a frangible join 34 in accordance with another embodiment of the invention. In this embodiment the indentations 45 are ellipses or oval shapes provided with a shallow curved bottom and sides similar to those shown in Figs 18A &18B however, each indentation is set to extend at an inclined angle with respect to the pin axis. The indentations are arranged in linear arrays extending longitudinally of the pin axis with the indentations in each array at opposite inclined angles to those in an adjacent array. By oppositely directing the angle of inclination, any rotation caused by inclined formations under application of a tensile load will be balanced. It will be appreciated that the indentations inAH25(45567071_l):SCPsome way mimic the pattern of protrusions on concrete reinforcement bar or “rebar”. Indeed, in some embodiments the indentations may be replaced by similarly shaped protrusions.

[0131] It will be also noted that in this embodiment the distal tip 22, 122 of the pin is peaked to facilitate easier insertion into the hole and provide for self-locating / centering. Preferably the apex angle of the peak aligns with the drill tip apex angle used to drill the hole.

[0132] Unlike conventional lathe-turned pins, which are generally limited to circumferential or helical surface features, these geometries are enabled by laser-based micro-machining processes that allow for precise, directional material removal along the pin axis. While the surface patterns are shown in relation to straight pins, any of the patterns exemplified in Figs 18A & 18B, 19A & 19B, 20A & 20B, 21A & 21B, 22A & 22B, 23A & 23B, 24A & 24B and 25A & 25B may equally be applied to bent pins or dogleg pins as described and shown elsewhere in this description.

[0133] As noted above and as depicted in Fig. 2B, the frangible join 34 provides a point at which the dental pin 12 will preferentially fail upon application of a bending moment thereby detaching the implantable body 20 from the attachment portion 30 and handpiece 50. Typically, the frangible join 34 is provided by a portion of the dental pin 12 having a circumferential groove thereby providing a reduced cross-sectional area to the adjacent implantable body 20 and attachment portion 30 and hence reduced resistance to bending. Advantageously bending forces applied to the dental pin 12 concentrate at the frangible join 34 beyond the material’s ultimate tensile strength (UTS) to fracture failure so that stresses in the remainder of the dental pin 12 and most significantly the implantable body 20 portion are kept below yield strength limit so that the implantable body 20 portion undergoes no or at least minimal plastic deformation prior to fracture of the frangible join 34 as seen in Fig. 2C.

[0134] The handpiece 50 comprises an elongate body 52 including a handle 53 having a longitudinal body axis B and a head 54 from which the respective dental pin 10 extends when attached to the handpiece 50. As can be seen the dental pin insertion axis Z of the insertion portion 24 is inclined by an offset angle a to the longitudinal body axis Y. Preferably the offset angle a is within ± 10° more preferably ± 5° of a drill angle P defined as an angle between a rotation axis Z' of a drill hand piece 500 (shown in Fig 26) used to drill the plurality of receiving holes into the tooth and a respective hand grip axis Y' of the handpiece. More preferably, theAH25(45567071_l):SCPoffset angle a is around the same as the drill angle p. Typically, this provides an offset angle a of between 45° and 85°, preferably between 66° and 76° and most preferably around 71°.

[0135] As seen in the schematic longitudinal cross section Fig 2A, the attachment portion 30 is embedded in the respective head 54 of the respective handpiece 50 with the dental pin 12 extending therefrom. In this embodiment, the handpiece 50, and more specifically the head 54, is overmolded about the attachment potion 30 of the dental pin 12 thereby fixedly attaching the attachment portion 30 and dental pin 12 to the handpiece.

[0136] The dentin pin 12 is typically made of a metal material suitable for use in dental implant applications such as a steel alloy, stainless steel, titanium or a titanium alloy or a composite body including a polymer matrix and a reinforcement phase such as fiberglass or carbon fibre reinforced polymer. The handpiece 50 is made from a suitable cheap material such as a plastics material and may be discarded or recycled after use along with the embedded attachment portion 30 of the dental pin 12

[0137] In some embodiments, rather than the straight or linear pin shown in Figs 2A - 2C, the exposed portion of the dental pin 12 may include a pre formed angulation, the angulation defining a “dogleg” geometry having a proximal portion and a distal portion meeting at a bend region as shown in Figs 12A to 12C. Other embodiments of a combination handpiece and dental pin 110 in accordance with the invention are shown in schematic longitudinal cross section views of Figs 3A-3D, 4A-4D and 5A-5C. These embodiments comprise a separate dental pin 112 which is releasably attachable to a separate handpiece 150.

[0139] Referring to Figs. Figs 3A-3D, the dentin pin 112 includes an implantable body 120 comprising a distal end 122 having an elongate insertion portion 124 defining a dentin pin insertion axis Z and an exposed portion 126 which in this embodiment is also elongate and extends along the insertion axis Z as a continuation of the insertion portion 124. In this embodiment, the implantable body 120 extends to an integral attachment portion 130 for attaching the pin 110 to the handpiece 150 and which is connected to the exposed portion 126 of the implantable body 120 by a frangible join 134 configured to preferentially fail upon application of a bending moment thereby detaching the implantable body 120 of the dental pin 110 from the attachment portion 130 and handpiece 150.AH25(45567071_l):SCP

[0140] In use the distal end 122 and insertion portion 124 are to be inserted into a hole drilled into the tooth and fixed with a dental cement while the exposed portion 126 extends from the respective hole in the tooth to be used as a framework and anchor for the curable restorative material. Demarcation between the insertion portion 124 and the exposed portion 126 is not necessarily fixed and may depend on the hole depth and the depth the pin is inserted into the hole. Typically, however, the hole is drilled to a predetermined depth and the pin selected to provide a predetermined length of insertion and a predetermined length of the exposed portion.

[0141] The dental pin 112 is typically of a circular cross section providing for cylindrical insertion 124, exposed 126 and attachment portions 130. Areas of an external surface 132 of the insertion portion 124 are textured or roughened, or include surface formations in the form of protrusions or cavities to enhance mechanical bonding with the settable cement for bonding the pin into the respective hole in the tooth. Similarly, areas of an external surface 144 of the exposed portion 126 are textured or roughened, or include laterally extending formations in the form of protrusions or cavities to enhance mechanical interlocking with the curable restorative material. In some embodiments the formations take the form of circumferential ribs or as seen in the Figs. 3A-3C, 4A-4D and 5A-5C, a helical thread. In other embodiments, areas of the external surface 132 of the insertion portion 124 and / or areas of the external surface 144 of the exposed portion 126 are textured with other patterns such as can be seen in Figs 18A &18B, 19A & 19B, 20A &20B, 21 A & 21B, 22A & 22B, 23A & 23B, 24A & 24B; and 25A & 25B and are described above in relation to the integral pin.

[0142] The frangible join 134 provides a point at which the dental pin 112 will preferentially fail upon application of a bending moment thereby detaching the implantable body 120 from the attachment portion 130 and handpiece 150. Typically, the frangible join 134 is provided by a portion of the dental pin 112 having a circumferential groove thereby providing a reduced cross-sectional area to the adjacent implantable body 120 and attachment portion 130 and hence reduced resistance to bending. Advantageously bending forces applied to the dental pin 112 concentrate at the frangible join 134 beyond the material’s ultimate tensile strength (UTS) to fracture failure so that stresses in the remainder of the dental pin 112 and most significantly the implantable body 120 portion are kept below yield strength limit so that the implantable body 120 portion undergoes no or at least minimal plastic deformation prior to fracture of the frangible join 134 as seen in Fig. 2C.AH25(45567071_l):SCP

[0143] The handpiece 150 comprises an elongate body 152 including a handle 153 having a longitudinal body axis Y and a head 154 from which the respective dental pin 110 extends when attached to the 150. As can be seen the dental pin insertion axis Z of the insertion portion 124 is inclined by an offset angle a to the longitudinal body axis Y. Preferably the offset angle a is within ± 10° of a drill angle P defined as an angle between a rotation axis Z' of a drill hand piece 500 used to drill the plurality of receiving holes into the tooth and a respective hand grip axis Y' of the handpiece. More preferably, the offset angle a is around the same as the drill angle p. Typically, this provides an offset angle a of between 45° and 85°, preferably between 66° and 76° and most preferably around 71°.

[0144] In contrast to the embodiment shown in Figs. 2 A - 2C, as seen in the schematic longitudinal cross section Fig 3 A, the attachment portion 130 is selectively attachable to the respective head 154 of the handpiece 150 so that the dental pin 112 extends therefrom by means of a releasable connection 160 comprising complementary connection formations (162 and 164 respectively) on the attachment portion 130 of the dental pin 112 and the head 154. The releasable connection may be provided with complementary formations allowing a friction fit, a snap fit, or a selectively releasable catch arrangement.

[0145] In this embodiment, the handpiece 150, and more specifically the head 154, includes a receiving formation in the form of an aperture 166 for receiving the cylindrical attachment portion 130 of the dental pin 112 to locate the dental pin 112.

[0146] In some embodiments such as seen in Fig 7A-7E and 10A & 10B, the releasable connection 160 relies on a friction fit wherein the dental pin 112 is releasably secured to the receiving formation 160 of the handpiece 150 by a friction elements to frictionally bind the pin part to the handpiece. For instance by means such as a taper fit, wherein the connection formation 162 on the attachment portion 130 is provided by a taper on the attachment portion 130 and / or the connection formation 164 on the head 154 includes a tapered aperture 166 so that insertion of the attachment portion 130 into the aperture results in a friction binding to hold and locate dental pin 112 with respect to the handpiece.

[0147] In other embodiments such as seen in Fig 3A - 3D, the complementary connection formations 162 and / or 164 may include one or more resilient formations which engage with a complementary formation to provide the releasable connection 160. By way of example,AH25(45567071_l):SCPreferring to Fig 3A, the aperture 166 includes a projection 168 for locating in a circumferential groove 170 on the attachment portion 130 of the dental pin 112 so as to provide for snap-fitting securement of the pin in the head of the handpiece.

[0148] In still further embodiments the releasable connection 160 may include one or more movable parts such as a movable pawl or toggleable component on the handpiece movable between an engaged position to engage a complementary formation on the dental pin 112 and a release position to disengage from the complementary formation on the dental pin 112. In the engaged position the movable component engages with the complementary formation on the dental pin 112 to selectively hold the pin and prevent extraction thereof, whilst in the release position the movable component engages with the complementary formation on the dental pin 112 to allow the pin part to be removed from the handpiece.

[0149] In some embodiments the complementary connection formations 162 and / or 164 may be configured to be compatible with standardized shanks for rotary and oscillating instruments as used for dental applications (such as defined in ISO 1797:2017) and exemplified in the embodiment shown in Figs 13 A & 13D. In such embodiments, the connection formation 162 on the attachment portion 130 is provided with a circumferential notch 163a or groove for receiving a complementary connection formation 164 in the form of a projection 165a on the head 154 to retain the pin axially and prevent inadvertent extraction. The projection may be biased to snap engagement with the notch to retain an inserted pin whilst allowing extraction of the pin by application of a threshold extraction force. Alternatively, the projection may include a selectively releasable locking mechanism to engage the groove and prevent extraction of the pin. In the embodiment shown, the complementary connection formation on the pin includes an angular drive formation such as lateral facing flat surface 163b to engage a complementary drive formation 165b on the head 154. The angular drive formation is used in a dental drill to apply rotation drive to the pin or drill however in this handpiece 150 it may be used to prevent rotation of the pin. In some embodiments the head 154 is fitted with a rotatable cap (not shown) connected to or carrying the complementary drive formation 165b so that an angular orientation of the pin may be adjusted by relative rotation of the cap with the handpiece 150.

[0150] As with the prior embodiment shown in Figs 2A-2C, the dental pin 112 is typically made of a metal material suitable for use in dental implant applications such as a steel alloy, stainless steel, titanium or a titanium alloy or a composite body including a polymer matrix and aAH25(45567071_l):SCPreinforcement phase such as fiberglass or carbon fibre reinforced polymer. In this embodiment the handpiece 150 may be re-used accordingly, the handpiece 150 may be made from a suitable cheap material such as a plastics material or from a more durable material for instance, a metal such as a stainless steel.

[0151] Figs 4A-4D and 5A-5C also show further embodiments of the invention comprising a separate dental pin 112 which is releasably attachable to a respective separate handpiece 150. Like reference notation is used for like parts.

[0152] In the embodiment depicted in Figs 4A-4D the pin part 150 the attachment portion 130 includes an end cap or head supporting connection formation 162. The end cap 131 is preferably over molded of a plastics material around the metal shaft allowing for greater control of the shape and configuration of the connection formation.

[0153] In the embodiment depicted in Figs 5A-5C separate dental pin 112 combines the attachment portion 130 and exposed portion 126 so that upon insertion, the entire pin part is detached from the handpiece and implanted into the tooth.

[0154] In some embodiments, rather than the straight or linear pins shown in Figs. 3A-3C, 4A-4C 4D and 5A-5C, the exposed portion of the dental pin 112 may include bends such as a dog leg bends shown in Figs 11 A to 1 ID and which will be described later in this document.

[0155] More detailed exemplary embodiments of the invention are shown in Figs 6A- 6E, 7A -7G; 8A-8F; 9A-9D; 10A-10E; 11A-11D, 12A-12C and 13A -13D.

[0156] Figs 6A-6E show a combination dental pin and handpiece 10 having a dental pin 12 and a handpiece 50. As with the embodiment shown in Figs 2A-2C, the dental pin 12 includes an implantable body 20 extending to an integral attachment portion 30 which is embedded in the respective head 54 of the respective handpiece 50. The handpiece 50, and more specifically the head 54, is overmolded about the attachment potion 30 of the dental pin 12 thereby fixedly attaching the attachment portion 30 and dental pin 12to the handpiece.

[0157] Figs 7A-7G show a handpiece 150 in accordance with an embodiment of the invention wherein connection formation 164 on the head 154 includes a tapered aperture 166 for receiving the attachment portion 130 of dental pin 112 as shown in Figs. 7F & 7G. The pin 112, which inAH25(45567071_l):SCPthis embodiment includes a straight cylindrical attachment portion 130, is held withing the tapered aperture by means of a friction fit. In other embodiments the sidewalls of the attachment portion 130 and the aperture 166 may have complementary tapers to provide a machine, or morse taper fit.

[0158] Turning to Figs 8A-8F, another embodiment of a handpiece 150 is shown wherein aperture 166 of connection formation 164 on the head 154 for receiving the attachment portion 130 of dental pin 112, includes resilient flaps 168 projecting inwardly from the circumference of the aperture toward the center thereof which provide a gripping force on the corresponding connection formation 162 on attachment portion 130 of the pin. In this embodiment, as seen in Fig 8F, three resilient flaps 168 extend both circumferential and radially toward the center of the aperture to create a spiral. The flaps 168 resiliently deform outwardly upon insertion of cylindrical connection formation 162 of pin 112, shown in Figs. 10A- 10E.

[0159] As seen with reference to cross-sectional view of Fig 9A, the attachment portion 130 includes an end cap or head supporting connection formation 162. The end cap is preferably over molded of a plastics material around the metal shaft of the pin. Attachment portion 130 also includes finger gripping formations 172 for enhancing grip of the pin when inserting and removing it from the handpiece 150 as seen in Fig 10A and 10E. The gripping formations extend radially from the attachment portion 130 and provide an insertion stop to prevent over insertion of the pin into the head of the handpiece 150.

[0160] In addition, with reference to Fig 9A and 9B, an external surface 132 of the insertion portion 124 and an external surface 134 of the exposed portion 126 are textured or roughened, with a helical thread to enhance mechanical bonding with the curable restorative material.

[0161] A variation of the pin 112 shown in Figure 9A- 9D is shown in Figs. 11 A-l ID which may be equally applied to any of the straight pin embodiments shown in Figs 2A-2C, 3A-3C, 4A-4C 4D, 5A-5C, 6A- 6E, 7A - 7G; 10A-10E, 11 A-l ID, 12A-12C and 13 A -13D. In this embodiment, elongate insertion portion 124 of the implantable body 120 includes a pre formed angulation geometry wherein, as can be seen with reference to Fig. 11 A, the elongate insertion portion 124 of the implantable body 120 is angularly offset from an axis X of the exposed portion 126 by an angle 0 thereby providing a bent implantable body 120. In this embodiment, return bends 135 and return length 136 of the attachment portion 130 above the frangible joinAH25(45567071_l):SCP134provide the pin with a “dogleg” 137 geometry. The dogleg 137 maintains alignment of insertion axis Z with the axis W of the attachment portion 130 thereby preserving the offset angle a between the dental pin insertion axis Z of the insertion portion 124 and the longitudinal body axis Y of the handpiece. Furthermore, alignment of the insertion axis Z with the axis W of the attachment portion 130 eliminates the generation of torque that may be generated under the application of an insertion force that may rotate the pin around axis W. The included bend angle 0 may be between 10° and 80° preferably in the range of about 25° to about 40° and typically around 35°.

[0162] The attachment portion 130 of the dental pin 112 may be located and frictionally held in the aperture 166 of connection formation 164 on the head 154 of the embodiment of the handpiece 150 shown in Figs 8A-8F. This allows for the orientation of the dogleg or bent portion of the dental pin 112 to be rotated with respect to the handpiece body axis Y as required. In particular, the pin may be set in the handpiece so that for a respective predrilled hole, the exposed portion 126 is angled toward the center of the tooth relative to an ergonomic angle to the handpiece 150. Thus the preformed angulation or dogleg pin eliminates the need to bend the pin after setting in place thereby removing the likelihood of pin breakage during bending.

[0163] Figs 12A-12C show an integral dental pin and a handpiece combination 10 incorporating a bent or dogleg dental pin 12. As with the embodiment shown in Figs 2A-2C, the dental pin 12 includes an implantable body 20 extending to an integral attachment portion 30 which is embedded in the respective head 54 of the respective handpiece 50. However the elongate insertion portion 24 of the implantable body 20 is angularly offset from an axis of the exposed portion 26 by an angle 0. Return bends and return length defining a dogleg is provided between the attachment portion 30 and the frangible join 34 so that insertion axis Z is aligned with the axis of the attachment portion 30 preserving the offset angle a between the dental pin insertion axis Z of the insertion portion 24 and the longitudinal body axis Y of the handpiece. Preferably the angle 0 is between 10° and 80° preferably in the range of about 25° to about 40° and typically around 35°.. The handpiece 50, and more specifically the head 54, is overmolded about the attachment potion 30 of the pin part 10 thereby fixedly attaching the attachment portion 30 and pin part 10 to the handpiece.AH25(45567071_l):SCP

[0164] As noted previously, in some embodiments, the dentine pin comprises a composite body including a polymer matrix and a reinforcement phase. The reinforcement phase may comprise glass fibres, silica fibres, quartz fibres, carbon fibres, or combinations thereof. In certain embodiments, the reinforcement comprises a plurality of continuous fibres extending along at least a substantial portion of the pin length, optionally in a unidirectional orientation, and embedded within a polymer resin matrix. Fibre reinforced dental posts are known to employ prestretched fibres embedded in polymer resin matrices (commonly epoxy and / or Bis GMA based), often using a high volume percentage of continuous fibres.

[0165] In some embodiments, the polymer matrix comprises an injection moldable thermoplastic resin selected from PEEK, POM (acetal), and / or other biocompatible engineering thermoplastics, optionally including radiopaque additives and / or fillers. In certain embodiments, the polymer matrix comprises a medically qualified PEEK grade having biocompatibility testing aligned with ISO 10993 1 and USP Class VI requirements (for example, implantable grade PEEK materials marketed for long term implantable medical devices), and the matrix is processed by injection molding, compression molding, extrusion, or related melt processing techniques. In other embodiments, the polymer matrix comprises a medical grade acetal (POM) material having certified biocompatibility credentials (e.g., USP Class VI and ISO 10993 cytotoxicity testing statements) for applications where such grades are appropriate. The pins could be made from straight formed rod material and subsequently heated and bent to form the dogleg portion or other desirable bent or form feature such retentive surface patterns.

[0166] In further embodiments, the polymer matrix comprises a thermoset resin, including epoxy systems, which cure to a highly cross linked structure. In some embodiments, the thermoset resin comprises a “medical grade” epoxy resin system characterised by biocompatibility testing to ISO 10993 (for example, EPO TEK MED 353ND is described in its technical datasheet as a biocompatible / high temperature epoxy and “ISO 10993 Tested / Fully Compliant,” demonstrating that ISO 10993-tested epoxy systems are commercially available).

[0167] In some embodiments, the dentine pin comprises a discontinuous fibre reinforced polymer, wherein short strand glass fibres (and / or other short fibres) are dispersed within the polymer matrix to increase stiffness and tensile strength compared to an unfilled matrix. This may be a thermoset resin or thermoplastic resin. Glass filled PEEK materials are commercially described as exhibiting increased mechanical strength and rigidity relative to unfilled PEEK,AH25(45567071_l):SCPsupporting inclusion of chopped fibre embodiments for injection molding. In other embodiments, the dentine pin comprises a continuous fibre reinforced composite manufactured by drawing fibre bundles through an impregnation region and a shaping die to wet out the fibres with the matrix resin and consolidate the composite into a rod like pin geometry, analogous to pultrusion processes in which fibres are impregnated with resin and then formed / cured within a die.

[0168] As discussed, in some embodiments, the pin includes a pre formed angulation for posterior tooth use, or “dogleg” geometry having a proximal portion and a distal portion meeting at a bend region. In thermoplastic matrix embodiments, the dogleg geometry may be molded directly during injection molding and / or formed by post mold heat forming, consistent with thermoplastics’ ability to soften and re solidify with heat, whereas in thermoset matrix embodiments the dogleg geometry is preferably formed during curing within the shaping tool / die because thermosets are usually non formable after cure. In continuous fibre embodiments, the dogleg may be formed during impregnation / consolidation by guiding continuous fibres through a tooling path that includes an angulation element (e.g., guide pins) while the matrix is in a low viscosity state, thereby enabling fibres to be wetted and consolidated in the bent geometry. Melt-impregnation approaches explicitly describe passing roving bundles over a submerged pin under tension to spread and impregnate the bundle, and reaction injection pultrusion approaches describe an injection chamber configured to achieve complete impregnation of the fibre bundles.

[0169] In some embodiments, as noted previously, the dentin pin external surface includes retention-enhancing surface features configured to increase mechanical interlocking with a resin cement and / or restorative material. Because highly cross linked fibre post matrices can exhibit limited chemical reactivity, micromechanical interlocking into surface irregularities is a significant contributor to retention; further, serrated fibreglass post may provide higher pull out force / strength than smooth designs. Accordingly, the external surface may include molded in micro ribs, circumferential rings, helical ribs, dimples, grooves, serrations, or other micro textures. Injection molding can replicate tool surface topography onto molded polymer parts, supporting mold in formation of micro textures. Alternatively, or additionally, the external surface may be laser patterned, laser etched, or otherwise micro machined depending on the pin material and manufacturing method; for example Er: YAG laser etching has been reported to enhance bonding strength of glass fibre posts, and laser surface texturing is described as aAH25(45567071_l):SCPcontrollable method for generating micro patterns for biomedical applications, including on polymers.

[0170] In some embodiments, the dentine pin includes a predetermined weakened or frangible region configured to enable snap off of the implantable body 20, 120 after cementation and / or build up, thereby permitting a flush or controlled-height termination without extensive chairside trimming and allowing the handpiece to be removed immediately after pin placement. The weakened region may be formed in the mold (e.g., reduced cross section, notch, groove) or created as a secondary operation (e.g., precision sawing or laser ablation). Laser micromachining / ablation enables micron level precision for texturing, and laser scribe and break methods enable controlled-fracture approaches wherein a scribe introduces a crack initiation site and subsequent loading propagates a controlled separation.

[0171] In one preferred embodiment, the dentine pin comprises continuous (full length) glass fibres impregnated with a high flow thermoplastic matrix (e.g., a high flow PEEK grade) and consolidated in a tool that defines a dogleg geometry, the tool including an angulation feature (e.g., 15-30°). The device further includes molded in external micro textures (micro rebar) to enhance mechanical interlock with cement, with optional laser surface patterning for additional retention.

[0172] Returning to the method, once the number of holes / pins has been determined, a corresponding number of dental pins and attached handpieces are prepared. The dental pins may have an integrated handpiece as exemplified in the embodiment shown in Figs. 2A-2C, 6A-6E and 12A-12C, or comprise separate pin parts 110 and handpieces 150 in accordance with the embodiments of the invention described above and / or exemplified in Figs, 3 A-3D, 4A-4D, SA-50, 7A-7G, 8A-8F, 9A-9D, 10A-10E, 11A-11D, 13A-13D.

[0173] Where separate pin parts and handpieces are provided, each dental pin 112 is attached to a respective handpiece 150 so that the dental pin 112 extends from the handpiece 150.

[0174] Each dental pin and respective handpiece are laid out for convenient access. This may involve each pin / handpiece being placed into a respective pin handpiece holder 200 so they are oriented correctly and separated adequately for rapid and ergonomic access. Orientation and ergonomics are essential as time is of the essence. The cementing process is a race againstAH25(45567071_l):SCPcement working time and rapid access without fumbling the pin delivery system assists in maximizing the efficiency of the process.

[0175] In this regard, with reference to Figs 14A - 14C and 15, a pin / handpiece holder 200 in accordance with another aspect of the invention is shown. The holder is in the form of a tray 200 as seen in Fig. 14A including one or more bays 201, each bay for receiving a head portion of a respective handpiece 50, 150 so that each handpiece is oriented correctly and separated adequately for rapid and ergonomic access. Each bay 201 includes a receiving formation such as a groove, rib, or notch for supporting and engaging the head portion of each handpiece. Each handpiece 50, 150, includes a corresponding locating formation to engage with the receiving formation 203 of the respective bay 201. In this embodiment, receiving formation is formed as an elongate slot 203 or groove configured to engage with a complementary rib 205 located at or adjacent the head end of each handpiece 10, 110. The elongate slot 203 is orientated generally vertically to provide a generally vertical insertion / extraction axis along which the handpiece 10, 110 is inserted or withdrawing from the respective bay. As seen in Figs 14A - 14C, either the handpiece 50 having an integral pin 12, or handpiece 150 having removable pin 112 may be compatible with holder 200. In some aspects of the invention each holder includes inter-engageable joining formations 209 allowing like holders to be secured together.

[0176] In an alternative embodiment, the holder is configured as a stand 210 to receive, locate and hold and present the handpiece to the user as seen in Figs 16A, 16B, 17A and 17C. The stand 210 shown in these figures includes a base 214 and an arm 216 extending from the base 214 and having at a distal end a receiving formation 208 for receiving a complementary formation 180 on the handpiece. In this embodiment the receiving formation 218 is an elongate lug which engages with a complementary elongate aperture 182 located within a longitudinal slot on the handpiece to present the handpiece upright and the pin clear of surrounding supporting structure on which the stand is positioned to prevent contamination. Figs. 17A and 17B show another embodiment of the stand 210 wherein a plurality of stands, each for supporting a respective dental pin / handpiece are shown in a linear array. While this array includes six (6) holders, any reasonable number of holders may be joined together as required. In this regard, in some aspects of the invention each holder includes inter-engageable joining means allowing like holders to be secured together.AH25(45567071_l):SCP

[0177] As seen in Fig. IB, the holes 5 are drilled following the pattern of indentations made in step 1. The drill is selected in accordance with diameter of the pins to be inserted. Typically the drill has a diameter of between 0.30 mm and 0.80 mm, most preferably between 0.4 mm and 0.675mm.

[0178] The holes 5 are drilled to a depth corresponding to the length of the insertion portion of the pins. Typical depths may be between 1.5 mm and 4.0 mm, most preferably between around 2.0 mm and 2.5 mm.

[0179] Once drilled the holes may be treated and prepared as required. This may involve:• Disinfecting and desensitising each hole particularly those holes in close proximity to or exposing dental pulp. This may include treatment with materials such as hydrogen peroxide, Gluma desensitiser or another glutaraledyde hema / water blend such as micro prime and filling the hole with a mineral trioxide aggregate in the event of a pulp exposure.• Applying suction and blowing air into the holes to remove all excess material• Using methods for the prevention of post drilling contamination for instance by having the patient bite on a cotton roll to keep the tooth and holes free from accidental saliva contamination.

[0180] Prepare an appropriate settable cement for cementing the pins into the holes. In some embodiments this may involve providing a capsule containing powder / liquid cement. Examples include Fuji Plus luting cement or Riva Luting Cement Plus or Ketac cement, ( GC, SDI and 3 M respectively). Cooling the capsules for instance by prior refrigeration and / or blast cooling the capsules for instance with an aerosol cold spray such as an endodontic pulp-test spray.

[0181] Activating and mixing the capsule in a high speed amalgamator in accordance with instructions and applying intermittent cooling at least subsequent to mixing. Mixing is an exothermic process releasing heat which will reduces the working time of the cement available for pin insertion.

[0182] Other types of appropriate dental cement may be used. For instance, a paste -paste type cement may be used in place of a powder / liquid type cement. Typically paste / paste typeAH25(45567071_l):SCPcements do not generate so much heat but which requires an extended working time regardless. The two pastes are mixed together and they also need to be placed typically into a device to enable a higher pressure ejection out of finer needle in order to get into the fine holes appropriate for pins.

[0183] Inject cement into each hole via an injection needle 7 of an appropriate gauge dependent on the diameter of the hole as seen in Fig 1C. Wider needles have an advantage of requiring less injection pressure than a narrower smaller gauge needle while running a higher risk of jamming in the hole at smaller degrees of misalignment between needle ais and hole axis.Typically the needle gauge may range from 24 gauge to 30 gauge depending on the diameter of the holes drilled.

[0184] Preferably the needle tip is inserted to the foot of each hole to ensure cement is placed into the bottom of the hole displacing air in the hole and minimising the likelihood of cement being placed prematurely with resultant air entrapment at the bottom of the hole. Preferably the needle tip is therefore angled to align with the axis of the holes so that it may be fully inserted into the hole reducing risk it will become jammed or caught on the walls of the hole halfway down for example. Preferably the needle includes a beveled tip so that when the tip is placed in the bottom of the hole it does not impede the exit of the cement from the end of the needle tip by virtue of the pressure at the bottom of the hole. Ideally the tip of the needle should have a bevel in the vicinity of 45 degrees.

[0185] Cement is injected into each hole until excess cement is observed being ejected from the hole indicating that the hole is full. The needle may then be withdrawn while continuously injecting cement to replace space vacated by the needle as it is withdrawn.

[0186] Following injection and removal of the needle syringe, excess cement may be removed preferably by high pressure air to reveal the mouth or opening of each hole. This allows unimpeded visualisation of the tops of each holes during the pin insertion step so that visual confirmation of sufficient cement may be confirmed. This process is designed for maximum efficiency to allow multiple pins to be cemented prior to setting of the cement, which may require redrilling of cemented holes.

[0187] It is an extremely demanding technique already, and this is one reason why this technique has not been evolved and popularised up until now apart from the lack of materialsAH25(45567071_l):SCPand methods and equipment to do the job. Everything must be done to make it simpler and easier, to make it a clinically acceptable process for the average dentist.

[0188] To achieve appropriate and necessary speed and efficiency the system has been engineered to optimise ergonomics and confidence with respect to pin position and pin retention in the delivery handpiece by utilising a patented pin placement instrument.

[0189] Accordingly, the invention provides an improved system and apparatus for the insertion of multiple pins into a tooth for providing a frame work to receive and anchor a curable restorative material for reforming or restoring a portion of a tooth. In one form the invention provides a dental pin attached or attachable to a respective handpiece and selectively detachable therefrom. The connection with the handpiece is adequately rigid and provides the pin with an identical insertion angle as the line of drilling from the original drilling handpiece thus minimising the probability of operator alignment and insertion errors and minimising individual pin insertion time, thus maximising the number of pins that can be inserted per cement mix. In many cases all the pins required for the restoration can be inserted in one cement mix using these materials and method. The handpiece also employs a similar feel and contra angle bend as the original metallic drill handpiece but without the expense. Accordingly the user may economically prepare a plurality of handpieces and attached pins arranged for ergonomic use in rapid succession.

[0190] Once the cement has been placed into each hole and the excess blown away, dental pins 12, 112 are inserted into each of the holes with the pre-arranged handpieces. The stands as shown in Figs 14A - 14B and 15A and 15B separate and present each handpiece enabling rapid finger grip access without disturbing adjacent instruments, and has the pin angled appropriately ready to pick up and use, as well as keeping the pin free from contamination from other instruments, gauze or cotton rolls with blood or saliva et cetera which may be on a conventional bracket table and which may touch the pin in other less disciplined pin handpiece alignment systems.

[0191] To insert a pin into a respective hole, the user selects a handpiece with the attached pin and manipulates the handpiece to insert the distal end of the insertion portion of the pin into the hole as seen in Figs ID(i) and ID(ii). Fig ID(i) shows use of a separate handpiece / pin combination as seen in for example in Figs 8A-8E and 9A - 9D. Fig ID(ii) shows use of aAH25(45567071_l):SCPintegrated handpiece and pin combination as seen in for example in Figs 2A-2C and 6A - 6E. Typically the pin is inserted so that the distal end contacts the bottom of the hole which may be accomplished by exerting a force on the handpiece.

[0192] Because the pins have a close fit to the hole as well as a textured outer surface, if the insertion angle is out more than a few degrees from axis of the hole, there will be substantial friction and resistance to insertion. However since the dental pin insertion axis A of the insertion portion 24 is inclined by an offset angle a to the longitudinal body axis corresponding to the drill angle P (or within a few degrees thereof) the drill handpiece, the mesio-distal pin angulation of the hole should naturally align with the insertion axis of the pin as held by the pin handpiece. However the bucco-lingual orientation may require checking to confirm the pin is actually going down to the foot of the hole.

[0193] Insertion of the pin into the hole displaces cement which is ejected around the sides of the pin. The ejection of cement also provides a visual indication that sufficient cement was injected into the hole to establish a bond. Once fully inserted, the handpiece may be manipulated to provide a bending load to the pin such as by manipulation of the handle to the buccal or the lingual direction therein shearing the pin at the frangible join weak point and leaving the implantable body 20, 120 in the tooth. The next pin may be inserted the same way. It will be appreciated that the use of a comparatively low cost handle, preferably with no motors or moving parts allows multiple combination handles / pins to be used in a single procedure enhancing the speed and economy with which the operator can install pins.

[0194] As noted above, insertion of cement and pins is limited by the curing time of the cement. That is to say, curing of the cement results in the cement viscosity increasing until it solidifies. Increasing cement viscosity increases the cements resistance to flow inhibiting or preventing injection into the holes. Likewise the curing of cement in the hole may prevent pin insertion.

[0195] It is conceivable that each hole may be filled with cement and a pin inserted before proceeding to inject the next hole with cement and insert a respective pin thereby allowing the dentist to maintain a close account of the cement’s curing status. However, alternating between tasks of cement injection and pin insertion may be inefficient meaning less holes are processed before the cement cures and requiring a new batch of cement to be prepared.AH25(45567071_l):SCP

[0196] It is therefore suggested that the cement injection / pin insertion steps are performed in batches. First, cement is prepared and a plurality of holes are injected with cement before proceeding to pin insertion of those holes. Accordingly discretion must be applied as to how many holes can be filled with cement and have the pin inserted before the cement cures to a state where it becomes unworkable.

[0197] Once the pins are inserted and the cement has sufficiently hardened, the set pins may be bent as required. Typically the exposed portion of each pin is bent towards the centre of the tooth or away from the circumference of the tooth as seen in Fig. IF.

[0198] Bending the pins towards the centre of the tooth in this manner ensures that they avoid the external surface profile of any core crown or restoration. If necessary, the pins may be bent to a severe angle and / or shortened where occlusal space is limited.

[0199] If the dental pins 112 are of the dog leg design exemplified in Figs 11 A - 1 ID, they may be inserted into a respective handpiece such that for a particular hole and ergonomic orientation of the handpiece, the exposed portion 126 will be delivered to be inclined towards the centre of the tooth obviating the need to bend the pins post insertion. Advantageously, by laying out the pins in a logical sequence such that each number of pin that is used will be angled more slightly towards a particular orientation. For example, in one implementation each needle / handpiece combination is prepared with reference to a clock face. A pin at the 12:00 o’clock position could be pin number one and this will be orientated to the six o’clock direction- pin number two will be placed in a tooth at the one o’clock position and angled towards the 7:00 o’clock position etc. Preparing and laying the pins out in a logical orientated position enables the operator to quickly place the pins with the bent portion facing towards the centre of the tooth and this saves the operator the aggravation and time of bending the pins, after the cement is set.

[0200] The above method creates a foundation for restoring a tooth with a composite core or a composite restoration - if using a composite core it is critical to go for the maximum strength for the greatest long-term durability - and to that end it is highly desirable to use a fibreglass reinforced Composite such as GC Everex flow around the pins to give extreme strength where the core engages the pins to ensure the stress transfer system is optimised through the crown through the core to the pin to the tooth.AH25(45567071_l):SCP

[0201] The reason a large number of pins is used is to minimise the stress on each individual pin and keep the stress below critical thresholds to ensure that the large chewing forces over a long period of time and the resultant stress cycling do not lead to the failure of the pin in 10- or 20-years time. There is strength in numbers and there is durability to be had by minimising the stress on each individual pin, so it is essential to use as many pins as possible up to a spacing equal to 1.0 times the diameter of the pin - this is a paradigm shift because previously this number of screwed in pins , especially in a line, could cause multiple micro cracks and possibly in-line cracking and potential problems with pulpitis , leakage and carries and softening of tooth structure with eventual retentive failure, but with the stress-free system the more pins that are used the greater the retention as long as the pins are separated by a minimum distance equal to 1.0-1.4 x the diameter of the hole used for the pin . There has to be a certain amount of tooth substance left in order to transfer the stress from the pin into the tooth without weakening the tooth.

[0202] Restore the tooth as a core and crown or as a standard large direct composite in accordance with standard practices.

[0203] As used herein, the term “about is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean. “About can be understood as within 15%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from context, all numerical values provided herein are modified by the term about.

[0204] Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

[0205] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a,"AH25(45567071_l):SCP"an," and "the" may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises," "comprising," "including," and "having," are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

[0206] When an element or layer is referred to as being "on," "engaged to," "connected to," or "coupled to" another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly engaged to," "directly connected to," or "directly coupled to" another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0207] Although the terms first, second, third, etc. may be used herein to describe various elements, compartments, components, regions, layers and / or sections, these elements, components, compartments, regions, layers and / or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as "first," "second," and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

[0208] Spatially relative terms, such as "inner," "outer," "beneath," "below," "lower," "above," "upper," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use orAH25(45567071_l):SCPoperation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the example term "below" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0209] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

[0210] Similarly it should be appreciated that in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, FIG., or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this invention.

[0211] Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.AH25(45567071_l):SCP

[0212] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.AH25(45567071_l):SCP

Claims

CLAIMS1. A combination handpiece and dental pin to be cemented into a receiving hole in a tooth, said handpiece comprising:an elongate body having a longitudinal body axis and supporting a handle and a head; and wherein said dental pin comprises:an implantable body for implantation into the tooth said implantable body having an elongate insertion portion at a distal end thereof, said elongate insertion portion defining a dental pin insertion axis, and an exposed portion to extend from the hole and form a framework for a curable restorative material for restoring a portion of said tooth; andan attachment portion at a proximal end connecting said implantable body to said head of said handpiece, anda releasable connection allowing for selective detachment of the implantable body from the handpiece;wherein the dental pin insertion axis of said respective dental pin attached to said handpiece is inclined by an offset angle to the longitudinal body axis.

2. The combination handpiece and dental pin of claim 1 wherein the offset included angle is between 45° and 85°, preferably between 66° and 76° and most preferably around 71°.

3. The combination handpiece and dental pin of claim 1 wherein the offset angle is ± 10° preferably ± 5° of an angle between a rotation axis of a drill hand piece used to drill the plurality of receiving holes into the tooth and a respective hand grip axis of the handpiece.

4. The combination handpiece and dental pin of any one of the preceding claims wherein the attachment portion is fixedly attached to said head of the handpiece.

5. The combination handpiece and dental pin of claim 4 wherein the attachment portion is at least partially embedded in the head of the handpiece.

6. The combination handpiece and dental pin of claim 5 wherein each handpiece is overmolded about the attachment portion to provide a unitary handpiece and dental pin.AH25(45567071_l):SCP7. The combination handpiece and dental pin of any one of the preceding claims 1 to 3 wherein the attachment portion is configured for selectively releasable attachment to said head of the handpiece.

8. The combination handpiece and dental pin of any one of the preceding claims wherein the releasable connection includes a frangible join configured to preferentially fail upon application of a fracture force thereby providing selective detachment of the implantable body from the handpiece.

9. The combination handpiece and dental pin of claim 7 wherein the attachment portion and the head include complementary connection formations providing selective attachment and release of the dental pin to the handpiece.

10. The combination handpiece and dental pin of claim 9 wherein the complementary connection formations are configured for friction fit connection.

11. The combination handpiece of any one of the preceding claims wherein each handpiece is formed of a plastics material.

12. The combination handpiece of any one of the preceding claims wherein the implantable body includes a pre formed angulation between the elongate insertion portion and the exposed portion.

13. The combination handpiece of claim 12 wherein the elongate insertion portion is angularly offset from the exposed portion by an angle between 10° and 80° preferably between about 25° to about 40° and most preferably around 35°.

14. The combination handpiece of claim 12 or 13 wherein the elongate insertion portion is axially aligned with the attachment portion such that the pin includes a return length defining a dogleg geometry.

15. A dental method for preparing a tooth to receive a curable restorative material for restoring a portion of said tooth, said method including the steps of:(A) preparing the tooth to provide a receiving surface for receiving the curable restorativeAH25(45567071_l):SCPmaterial;(B) drilling a plurality of receiving holes into the tooth at the receiving surface;(C) providing a plurality of dental pins each dental pin attached to a respective handpiece and including a distal end and a dental pin insertion axis;(D) injecting a settable cement into each hole of the plurality of holes(E) manipulating each handpiece to insert the respective distal end and an elongate insertion portion of one of a respective dental pin of said a plurality of dental pins into each hole; and(F) detaching each handpiece from the respective dental pin so that a portion of each dental pin extends from the respective hole.

16. The dental method of claim 15 wherein each receiving hole is drilled to have a diameter larger than a maximum lateral width of the respective insertion portion to be inserted into the hole.

17. The dental method of claim 15 wherein each receiving hole is drilled and each respective dental pin is sized to provide a surrounding clearance on all sides of the pin of between 10 and 100 microns and more preferably around 35 microns (0.035mm) for cement.

18. The dental method of claim 15 wherein each hole is drilled adjacent a periphery of said receiving surface of said tooth.

19. The dental method of claim 15 wherein the step of drilling a first plurality of receiving holes includes drilling each hole to a predetermined depth, preferably a depth between 1.5 mm and 4.0 mm, most preferably between around 2.0 and 2.5 mm.

20. The dental method of claim 15 or 16 wherein the step of drilling a first plurality of receiving holes includes drilling each hole of a predetermined diameter of between 0.30 mm and 1.20 mm, preferably between 0.5 mm and 0.8mm. and most preferably around 0.6mm.AH25(45567071_l):SCP

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