SE1651713A1

SE1651713A1 - Dental superstructure and method for producing a dental superstructure

Info

Publication number: SE1651713A1
Application number: SE1651713A
Authority: SE
Inventors: Kazemi Reza
Original assignee: 3D Tech Sweden Ab
Priority date: 2016-12-21
Filing date: 2016-12-21
Publication date: 2018-06-22
Also published as: SE542652C2

Abstract

The present disclosure relates to a method for producing a dental superstructure (1) comprising an extending part (11), configured to resemble a tooth or a set of teeth, and at least one interface part (9), configured to connect the superstructure (1) to an implant (4). The extending part (11) is obtained with an additive manufacturing process and the interface part (9) is prepared as a separate piece. A first connector is formed on the interface part (9) by means of and a second connector feature in the extending part (11). The first connector of the interface part (9) can be attached to the second connector of the extending part (11). This allows a greater freedom of choice of location when placing implants in a jaw bone.

Description

DENTAL SUPERSTRUCTURE AND METHOD FOR PRODUCING A DENTALSUPERSTRUCTU RE Field of the invention The present disclosure relates to a method for producing a dental superstructurecomprising an extending part, configured to resemble a tooth or a set of teeth, and atleast one interface part, configured to connect the superstructure to an implant,wherein the extending part is obtained with an additive manufacturing process andthe interface part is prepared as a separate piece.

The present disclosure further relates to a corresponding dental superstructure.

Technical background Such a method is disclosed in WO-2015/090518-A1. That document shows thebuilding up of a dental superstructure on top of an interface part that may be astandard component. The interface part, which is not made up by means of anadditive manufacturing process, may have sufficiently small tolerances to connectproperly to an implant without costly post-processing of the surfaces intended toconnect with the implant, which provides for a less expensive superstructure.

One problem with superstructures of the initially mentioned kind is that they primarilyallow use under rather simple circumstances, mostly to replace a single tooth andwhere the underlying bone tissue provides easy access to the implant.

Summary of the invention One object of the present disclosure is therefore to provide a method for producing adental superstructure that is more versatile.

This object is achieved by means of a method as specified in claim 1. More specific-ally, in a method of the initially mentioned kind, there is formed a first connector onthe interface part, and a second connector is formed in the extending part whileproducing the latter by means of additive manufacturing. The first connector featureof the interface part can be connected to the second connector feature of theextending part.

This provides a more flexible way of producing a superstructure. For instance, theextending part may be produced to extend with additive layer planes having a normal which extends obliquely with respect to the Iongitudinal axis of a screw that is used toattach the interface part to the implant. Also, when a bridge replacing a plurality ofteeth is formed, and is intended to be attached to several implants, those implantscan be allowed to extend in mutually different directions.

This provides for a more versatile superstructure.

The first connector may be provided on the interface part by means of additive manu-facturing. This makes it possible to readily enable the use of connectors adapted tothe superstructure. For instance, the connectors' length can be varied depending onthe space available in the superstructure.

The interface part may be provided by means of milling and/or turning, and may be astandardized component that is series produced.

The first connector may be provided with an outer conical surface and the secondconnector with a corresponding inner conical surface. Conical surfaces provide aninterface that allows rotation in between the first and second connectors to enablelocking features, and can take up significant loads along the connector axes.

The first and second connectors may provide a mating bayonet mount which pro-vides for reliable and easy connection of the parts. The manufacturing method mayalso include connecting the first and second connectors to each other.

The outer end of the interface between the first and second connectors may sub-sequently be sealed, for instance by welding or the provision of a glue. This reduces microbial entry into the superstructure.

A single interface part may be provided, the extending part forming a dental crown.Alternatively, a plurality of interface parts may be provided, allowing connection toseveral implants, the extending part forming a dental bridge.

The extending part and optionally the first connector may be produced by electronbeam melting, EBM, selective laser melting, SLM, blown powder technologies or ink-jet printing. ln most cases, the superstructure is made from metal powder or wire, butceramic materials, plastic and various composites may also be conceivable.

The present disclosure also considers a dental superstructure comprising features asproduced by the above discussed method.

Brief description of the drawinqs Fig 1 shows in cross section a denta| superstructure according to prior art about to be connected to an implant.

Fig 2 shows a perspective view of an interface part according to an example of the present disclosure.

Fig 3 shows a side view of the interface part in fig 2 with an attached connector feature.

Fig 4 schematically shows in cross section an anatomical/extending part with aninterior connector feature designed to mate with the connector feature of fig 3.

Fig 5 schematically shows the anatomical part of fig 4 with an interface part similar tothe one of fig 3 attached thereto.

Fig 6 shows a denta| bridge with multiple interface parts.Fig 7 illustrates in more detail an extending part as of fig 4.Fig 8 shows in perspective view an interface part with an attached connector feature.

Fig 9 shows a perspective view of a part of the interior connecting feature of theextending part as seen from the interior thereof.

Detailed description The present disclosure relates to methods and devices for denta| restoration. Toreplace lost or destroyed teeth in a patient's mouth, there exist techniques for attach-ing biocompatible implant screws in the jaw bone on the patient and, once the im-plant has been connected to the bone tissue, attaching superstructures to theimplant. The superstructures comprise extending anatomical parts that may becarefully designed to resemble the missing tooth or teeth.

Fig 1 shows schematically in partial cross section a denta| superstructure 1 accordingto prior art, about to be connected to an implant 3. When, as illustrated, a single toothis replaced, an implant screw 3, made in a biocompatible material such as titanium, is surgically attached in the jaw bone 5 of a patient. The implant 3 is allowed to rest for a number of days or weeks, such that the jaw bone 5 heals, and the implant 3becomes firmly connected to the bone 5 (osseointegration).

Then, a superstructure 1 comprising an extending or anatomical part 11 or piece isattached to the implant by means of an attachment screw 7, which is screwed intothe implant 3. The extending part 11 is produced such that its geometry resemb|es areal tooth, preferably the tooth it replaces, if available. This provides an aestheticallyappealing tooth replacement and facilitates chewing.

Traditionally, such superstructures have been made by milling a solid piece of metalinto a desired shape using CAD/CAM techniques. Such a process is however veryexpensive, especially if a bridge replacing a number of teeth is formed.

More recently, techniques have been introduced where additive manufacturingprocesses are used to produce the superstructure.

Additive manufacturing processes in this context means technologies where a pieceof material is built up, layer by layer, similar to plastic 3D printing techniques. To builda metal based piece for instance, a thin layer of metal powder may be applied to apreviously produced layer. The powder is then melted or sintered to integrate with theprevious layer by applying energy, for instance by means of an electron beam or ahigh-energy laser beam. As an alternative to powder, thin wires can be applied. Theprocess is based on a 3D model describing the desired shape of the piece.

Such techniques are well known per se. Electron beam melting, EBM, selective lasermelting, SLM, blown powder technologies and various ink-jet printing technologiesmay be considered. lt is possible to generate an entire superstructure by means of additive manufactur-ing. However, some post-processing is then needed to ensure the required manu-facturing tolerances, as tolerances of the interfaces to the implant are very strict.Milling etc. is therefore still needed to some extent. Therefore, it has been suggested,as described in the aforementioned document and in fig 1, to produce the super-structure's extending part 11 on top of a pre-manufactured interface part 9. Thisreduces the need for post-processing, and the interface part can be a standardcomponent produced in a comparatively efficient process, even though the finished superstructure is unique, based on the recipient's replaced tooth for instance. Theinterface part 9 may thus be series produced at relatively low cost.

The present disclosure seeks to obtain a dental superstructure that is more versatile.This is achieved by providing a connector element between an interface part and theextending, anatomical part of the superstructure, that extends from the recipient's jaw bone and gingiva and into the oral cavity.

Fig 2 shows a perspective view of an example of an interface part 9. This piece isshaped depending on the implant screw used. lt may include an opening 17 throughwhich the attachment screw may enter, and an inner, upwards facing circumferentialsurface (not shown) on which the head of the attachment screw rests when thesuperstructure is attached to the implant screw. As shown, protrusions 19 may beprovided around the outer periphery of the interface part 9 that fit into a correspond-ing shape in the implant screw to make sure that the interface part 9 does not turnwith respect thereto.

Fig 3 shows a side view of the interface part 9 in fig 2 with an attached first connector13. The first connector 13 may be produced on top of the interface part 9 by meansof an additive manufacturing process as described earlier. This allows the firstconnector 13 to be easily adapted to the circumstances where it is supposed to beused. For instance, an optimum length to fit in the extending part where it is to beused can be chosen. As an alternative, however, it would be possible to produce thefirst connector 13 together with the interface part 9, in one process and as a standardized component.

As will be disclosed, the first connector may comprise a conical connection surface21 with lugs 23 protruding therefrom. As shown, the inner, upwards facing circum-ferential surface 25 on which the head of the attachment screw is intended to rest may also be provided inside the first connector 13.

Fig 4 shows in cross section an anatomical/extending part with an interior secondconnector 15 feature designed to mate with the first connector 13 of fig 3. As shown,the first connector 13 may be provided as a male connector and the second connect-or 15 as a female connector although other configurations are conceivable. Thesecond connector 15 thus has an inner conical surface and locking features inter-acting with the lugs 23 of the first connector 13, forming a bayonet mount as will be shown. lt should be noted that the connector axis 27 of the second connector 15 canhave a wide range of angles as vis-a-vis the planes in which the layers of the extend-ing part 11, built up by additive manufacturing, extend. This is an advantage ascompared to the superstructure in fig 1, where the axis of the attachment screw 7must more or less coincide with the normal of the layers' planes in the extending part.This provides a much greater geometric freedom with respect to the relation betweenthe implant and the superstructure. The surgeon therefore has a greater freedomwhen locating the implant screws, and can for instance locate the implant screw at ajaw bone location with best possible jaw bone quality. lt can also be avoided thatneighboring natural teeth are disturbed by the implant or the superstructure.

Fig 5 schematically shows the extending part of fig 4 with an interface part similar tothe one of fig 3 attached thereto. The superstructure may be polished and given asurface treatment to provide a color with a tooth-like appearance as is known per se.

As shown, a channel 29 is also provided through the extending part and may becurved. The attaching of the superstructure to the implant may be carried out with atool extending through this channel. When the superstructure is firmly attached to the implant, the channel 29 may be sealed with a composite glue.

As shown, the circumferential surface 25 intended to support the screw head may be located also in the interface part 9.

The advantage of the present disclosure is even more pronounced in dental bridges,resembling multiple teeth and having more than one attachment point. Fig 6 shows adental bridge 31 with multiple interface parts 9. As shown, such interface parts mayextend along connector axes 27 that are not mutually parallel. Therefore, a specificrelationship between each of those axes and the planes in which the layers of theextending parts are located is not possible. Those layers will extend in mutuallyparallel planes throughout the extending part 11. Precision of fit is important in case asuperstructure is supported by more than one implant. Osseointegrated implantshave little resilience in the bone. Lack of passive fit between supporting implants anda superstructure increases the risk of biomechanical stress development when thesuperstructure is screw-tightened to the implants by means of attachment screws.Such stresses may cause micro-fractures of the bone surrounding the implant, ischemia, and other adverse effects that may negatively influence implant longevity.

The superstructure of the present disclosure may be tailored to a set of implants withhigh precision.

Fig 7 illustrates in perspective and in more detail an extending part 11 as of fig 4. Asillustrated, the female second connector 15 presents a conica| inner surface 28 whichcorresponds to an outer conica| surface 21 of the first connector 13, as shown in fig8. Returning to fig 7, the second connector 15 further comprises Iocking means 33,35 that allows the first connector 13 to be locked in the second connector 15 as will be described.

Fig 8 shows in perspective an interface part 9 with an attached connector feature 13.As mentioned, the first connector 13 has a conica| outer surface 21. This shape iswell suited to take up significant loads against the corresponding mating surface, forinstance when the recipient is chewing. Further, two lugs 23, protruding from theconica| surface are provided to lock the first connector 13 to the second connector 15 with Iocking means 33, 35 therein.

Those Iocking means are shown in fig 9 illustrating a perspective view of a part of theinterior connecting feature/connector 15 of the extending part 11 as seen from theinterior thereof. For each lug 23 of the first connector 13, the connector 15 of theextending part 11 may have a groove 35 leading to a recess 33 in the inner conica|surface 28. The first and second connectors may therefore be connected by slidingthe first connector 13 into the second connector 15 with the lugs 23 of the formerrunning in the grooves 35 of the latter. When the conica| surfaces 21, 28 are fullyconnected, the lugs 23 have entered the recesses 33. The first connector 13 maythen be turned with regard to the second connector 15, optionally using a tool toprovide the needed torque, such that the lugs 23 run in the recesses 33, away fromthe grooves 35. This may be carried out optionally until the lugs 23 reach the ends ofthe recesses 35. The recesses 33 may be open upwards (not shown). The lugs 23together with the grooves 35 and the recesses 33 form a bayonet mount. ln theillustrated case, two lugs 23 and two corresponding recesses 33 are used. However,three, four or more lugs/recesses would also be conceivable. lt should be noted that a significant torque may be needed to turn the first connectorin this way. Therefore, no additional Iocking features may be needed once the connectors 13, 15 have been assembled in this way. However, the skilled person 7 may make this connection permanent in a number of ways, for instance with a small spot weld (not shown) connecting the two pieces when assembled. lt is also possible to provide a weld joint between the connectors 13, 15 whenassembled to avoid microbial Ieakage into the superstructure. This can be donealong the outer end 37 (of. fig 5) of the interface between the first and second connectors 13, 15.

The present disclosure is not restricted to the above-described examples and may be varied and altered in different ways within the scope of the appended claims.

Claims

1. A method for producing a dental superstructure (1) comprising anextending part (11), configured to resemble a tooth or a set of teeth, and at leastone interface part (9), configured to connect the superstructure (1) to an implant(4), wherein the extending part (11) is obtained with an additive manufacturingprocess and the interface part (9) is prepared as a separate piece,characterized by: -forming a first connector on the interface part (9), and -forming a second connector in the extending part (11) while producingthe extending part (11) by means of additive manufacturing, such that the firstconnector of the interface part (9) can be connected to the second connector ofthe extending part (11).

2. Method according to c|aim 1, wherein the first connector (13) is provided on the interface part (9) by means of additive manufacturing.

3. Method according to c|aim 1 or 2, wherein the interface part (9) is provided by means of mi||ing and/or turning.

4. Method according to any of the preceding cIaims, wherein the firstconnector (13) is provided with an outer conica| surface (21) and the secondconnector (15) is provided with a corresponding inner conica| surface (28).

5. Method according to any of the preceding cIaims, wherein the first and second connectors are provided a mating bayonet mount (23, 33, 35).

6. Method according to c|aim 4 or 5, wherein the first and second connectors (13, 15) are connected to each other.

7. Method according to c|aim 6, wherein the outer end (37) of the interface between the first and second connectors (13, 15) is subsequently sealed.

8. Method according to any of the preceding claims, wherein a singleinterface part is provided, the extending part forming a denta| crown.

9. Method according to any of the claims 1-7, wherein a plurality of interface parts (9) is provided, the extending part forming a denta| bridge (31).

10. Method according to any of the preceding claims, wherein theextending part is produced by e|ectron beam melting, EBM, se|ective laser melting, SLM, blown powder technologies or ink-jet printing.

11. A denta| superstructure (1) comprising an extending part (11),configured to resemble a tooth or a set of teeth, and at least one interface part(9), configured to connect the superstructure (1) to an implant (4), wherein theextending part (11) comprises a material obtained with an additive manu-facturing process and the interface part (9) comprises a separately producedpiece, characterized by: - the interface part (9) comprising a first connector (13) formed thereon,and -the extending part (11) comprising a second connector (15) formedtherein, -wherein the first connector of the interface part (9) can be connected tothe second connector of the extending part (11), such that the interface part (9)can be firmly attached to the extending part (11).