Patent Application
20160278887
The present invention generally relates to dental implants, particularly endosseous dental implants. The invention more particularly relates to abutments of such implants, which reduce the risk of infecting the gingiva in proximity of the dental implant.
Dental implants as well as dental abutments exist nowadays in a great variety of different shapes and materials. The shape of the dental implant is chosen amongst others according to the number of teeth, which are replaced, the thickness of the osseous material and the position of the tooth inside the oral cavity. In some cases only one tooth is replaced, in other cases multiple teeth or all the teeth are replaced.
Such a dental implant comprises multiple parts: an implant fixture, at least one abutment and the tooth crown or dental prosthesis. The implant fixture is substantially cylindrically shaped with a circular base and is inserted into the bone to act as an artificial root. The implant fixture is typically made of titanium or a titanium alloy and is inserted into an opening, which has been bored into the bone. Once inserted, the bone has to grow into grooves on the surface of the implant fixture to fix the implant in the desired position (osseointegration), before any pressure can be put onto the implant fixture.
After the healing process is finished, at least one abutment is connected to the implant fixture. The abutment is usually made of a metallic material for hygienic reasons such as e.g. titanium and has an internal passageway with a screw passing through. The screw engages a thread inside the implant fixture to hold the abutments and the tooth crown or artificial prosthesis in place.
The dental implant described in the European patent application EP 1 269 932 A1 corresponds to a typical dental implant comprising multiple parts: an implant fixture, a first abutment, a second abutment with a tooth crown or a dental prosthesis.
The implant fixture fastens the dental implant to the bone of a patient. The implant fixture is cylindrically shaped with a circular base having a diameter based on the thickness of the available osseous material. The implant is typically self-tapping and it is screwed into a borehole of the patient's bone provided to be coaxial with the central axis of the implant. After the implant fixture has been screwed into the bone of the patient, the outer surface of the implant fixture is in direct contact with the bone. The implant fixture comprises an upper abutment connector for connecting the first abutment to the implant fixture in such a way that the first abutment does not rotate relative to the implant fixture.
The implant fixture has an internal thread in axial direction. The internal thread is coaxial with the central axis of the implant fixture for engaging a screw that fastens the first abutment and the second abutment to the implant fixture. Before the screw engages the implant fixture, the first abutment and the second abutment are inserted in axial direction, coaxial with the central axis of the implant, into the implant fixture. The implant fixture connector is arranged on the osseous side of the first abutment, while the upper abutment connector is arranged on the intraoral side of the implant fixture.
A further example of such an implant fixture connector and an upper abutment connector are disclosed in the European patent application EP 2 529 692. The implant fixture connector is a hexagon prism, preferably a regular hexagon prism with six outward flats, which engage the first abutment connector which has the negative shape of the implant fixture connector, with six inward flats. In assembled state the six outward flats are substantially in direct contact with the inward flats. According to the European patent application EP 2 529 692, the external surface of the first abutment is in assembled state partly in direct contact with the gingiva.
The first abutment has also a second abutment connector connecting with the first abutment connector of the second abutment in such a way that the first abutment does not rotate relative to the second abutment. The second abutment connector has six outward flats, which engage the six inward flats of the first abutment connector of the second abutment.
A screw engages the internal thread of the implant fixture such that the internal thread of the implant fixture is aligned with a first passageway through the first abutment and a second passageway through the second abutment. After the screw has been inserted through the first abutment and the second abutment into the internal thread of the implant fixture, the screw is fixed. As a result the first abutment and the second abutment cannot move relative to the implant fixture.
Even if the screw is tightly fixed and even if the contact surfaces of the abutments and the fixture are machined such that they engage accurately, there still are gaps where the contact surfaces engage. A gap is present between the first abutment and the implant fixture and a further gap is present between the first abutment and the second abutment.
U.S. Pat. No. 6,244,867 B1 describes a multi-part abutment adapted for use with dental implants such as cylindrical-shaped endosseous dental implants; having an internal opening or passage with an internal, noncircular shape at the top, either internally or externally, includes part one that engages the opening or passage in, or projection at the top, of the implant at the distal end of part one, and fits into abutment part two, at the top end of part one. Part two has at its distal end a multi-sided cavity that interdigitates with a multi-sided periphery or other connector on part one so that part two can be placed in a plurality of positions over part one. At the top end of part two is a prosthesis-engaging or prosthesis-forming projection which may be at an angle to the longitudinal axis of the implant, or lie on the longitudinal axis of the implant. Internal passages inside the two abutment parts are collinear when joined to one another in their intended configuration, permitting the use of a single fastener to join the two abutment parts to one another and to the dental implant, with part two covering part one and forming a sealed margin with the top of the implant.
DE102009057754A1 describes a dental implant which comprises an implant screw with an external thread, an implant abutment and a tightening screw which can be screwed into the implant screw and by which the implant abutment is connectable or connected with the implant screw, wherein the implant screw rests against a contact surface of the implant abutment with a contact surface. To improve such dental implant, the implant screw and the implant abutment are made of a ceramic material at least in the region of their contact surfaces. The contact surface of the implant screw and the contact surface of the implant abutment are ground in against each other.
WO2004/002358 discloses a spacer (3) with an associated adapter (4) which is designed to be fitted on an implant (1). The adapter comprises first and second portions (4b, 4c) designed to cooperate with the spacer and the implant, respectively, for securing the spacer on the implant. The adapter is completely enclosed by the spacer and the implant, and the first portion of the adapter can be designed with slits for forming resilient elements on said portion and/or with penetrating parts which, when the adapter and the spacer are joined together, are deformed as it penetrates into opposite parts in the spacer material. The spacer and the adapter can in this way be easily held together upon application to the implant and can be taken apart when completion work is performed on the spacer.
In the above described implants, the second abutment is pressed against the shoulder of the implant i.e. on a relatively small contact surface between the second abutment and the implant fixture. The mechanical forces of the screw and of the chewing are thus directly exerted on the implant fixture via a small contact surface which is situated at the top of the implant fixture.
Furthermore, as there are different types of implant fixtures and implant fixtures of different length, the implant fixture is sometimes inserted such that the intraoral surface of the implant fixture is level with the bone and sometimes such that the intraoral surface of the implant fixture is not level with the bone, but protrudes into the oral cavity. As a result, the exterior surface for some of the implant fixtures is not only in direct contact with the jawbone but it is partly also in direct contact with the gingiva.
There is a risk that bacteria accumulate in the gaps even if the gaps are microscopic. As a result, the gingiva in direct contact with the gaps may be become infected and in the worst case, the implant must be removed.
A dental implant is provided herein with a reduced risk of infecting the gingiva in contact therewith.
The dental implant thus has an intraoral surface and comprises:
The intraoral surface of the dental implant is the upper surface of the implant fixture which is exposed to the oral cavity when the implant fixture is implanted in the jaw bone. The osseous surface of the implant fixture is in direct contact with the bone, such as e.g. the jawbone. The dental implant comprises an implant fixture, a first abutment and a second abutment connectable to the implant fixture. The implant fixture is connectable to a patient's bone. The implant fixture comprises an internal thread and an upper abutment connector. The first abutment comprises an implant fixture connector, which is connectable to the upper abutment connector of the implant fixture. The first abutment further comprises a second abutment connector and a first passageway. The second abutment comprises a first abutment connector, which is connectable to the second abutment connector of the first abutment. The second abutment also comprises a second passageway. The first abutment and the second abutment are attachable to the implant fixture by a screw, which is insertable through the first passageway and the second passageway into the internal thread of the implant fixture.
In its assembled state said implant fixture is in contact with said second abutment, and a substantially horizontal gap is formed between said first and second abutment and this gap is situated at a distance d below said intraoral surface.
In other words, the first abutment is hidden inside the second abutment and the implant fixture so that the gap between the first abutment and the implant fixture is not exposed to the gingiva.
As a consequence, also in the assembled state, a substantially vertical gap (or contact surface) is formed between the second abutment and the implant fixture.
The horizontal gap or contact surface between the first and the second abutment is not in contact with the gingiva since it is at a distance d below the intraoral surface of the implant fixture. The second abutment has thus no horizontal gap or contact surface with the implant fixture.
The fact that the gap between the first abutment and the second abutment is sunk into the implant fixture and not above the interoral surface as it is traditionally the case, allows to create an exposed gap, which has a reduced surface which is exposed to the gingiva. Indeed, since this gap is sunken in the implant fixture, the gap between the second abutment and the implant fixture is made substantially vertical or slightly inclined outwards, preferably in an angle of between 70° and 90°, more preferably in an angle of between 75° and 89° and most preferably in an angle of between 82° and 87° with regard to the central axis of the dental implant.
Such a substantially vertical gap is easier to close tightly and thus the risk of bacteria being able to colonize this gap is reduced. The risk of infecting the gingiva, which is in direct contact with the dental implant, is reduced since there is only one substantially vertical gap, which is exposed to the gingiva instead of one respectively two horizontal gaps. The dental implant is thus more hygienic.
Another advantage of the present dental implant is that the forces occurring when chewing are mostly transferred to the first abutment and not on the top surface of the implant fixture. The forces are thus transferred deeper into the implant fixture and to a larger contact surface between the first abutment and the implant fixture. Furthermore since the gap between the second abutment and the implant fixture is substantially vertical, the construction is more solid when submitted to horizontal forces during chewing. As the dental implant has an exposed gap, which is substantially perpendicular to a central axis of the internal thread, the pressure applied onto the first abutment and the second abutment is higher than the pressure applied onto a surface, which is oblique to the central axis.
Preferably, the contact surface between the second abutment and the implant fixture is conical to guarantee a tight fit. The exposed gap is thus reduced to an annular slit around the lower part of the second abutment
According to a preferred embodiment of the invention, the gap formed between the first abutment and the second abutment is situated at a distance d below the intraoral surface, the distance d being preferably between 0.001 and 1 mm, more preferably between 0.01 and 1 mm, more preferably between 0.01 and 0.5 and most preferably between 0.01 and 0.3 mm.
The upper abutment connector of the implant fixture has advantageously a conical section and an interior surface having a downwardly inwardly tapered flat. The inwardly tapered flat is engageable with a conical section of an exterior surface of the internal fixture connector of the first abutment with downwardly inwardly tapered flats. In the context, downwardly specifies a direction from the intraoral side to the osseous side. Thanks to the conical profile, the first abutment is very securely attached to the implant fixture when assembled.
The first abutment can be made of titanium, Cobalt-chrome (a metal alloy of cobalt and chromium) or any other suitable material used in dentistry. As titanium or Cobalt-chrome can be machined more easily than a ceramic material, the fitting accuracy of the first abutment and the implant fixture is increased. The tolerances for the fitting accuracy are preferably in range between 7 to 10 μm. Furthermore, titanium or Cobalt-chrome is more ductile than a ceramic material, such as e.g. zirconium. As a result the first abutment can level out the any uneven surface between the first abutment and the implant fixture.
The implant fixture connector is preferably connectable to the upper abutment connector such that the first abutment does not rotate relative to the implant fixture. The first abutment connector is connectable to the second abutment connector in such a way that the second abutment does not rotate relative to the first abutment. As a result, the pressure applied by the screw onto the implants and the fixture can be reduced. This is especially useful when the implant concerns a single tooth which should obviously not rotate around its vertical axis. However when the implant is destined to be used to secure a bridge of two or more teeth, it may be useful that the implant allows a certain degree of rotation around the vertical axis so the bridge can be more easily fastened to the implant.
According to a preferred embodiment of the invention, the implant fixture connector is a first hexagonal prism with six outward flats and the upper abutment connector has a fixture opening with six inward flats. The fixture opening engages the first hexagonal prism in such a way that the first abutment does not rotate relative to the implant fixture in assembled state.
The first abutment connector is preferably a second hexagonal prism with six outward flats. The second abutment connector can have six inward flats, which engage the second hexagonal prism in such a way that the first abutment does not rotate relative to the second abutment.
According to a preferred embodiment of the invention, the first abutment comprises one or more clipping, clamping or gripping elements to connect to the second abutment. Thanks to the clipping, clamping or gripping elements, the first abutment may be detachably connected to the second abutment before being inserted into the implant fixture and before the screw is inserted into the first and second passageways. As a result it is more practical for the dentist to insert the first abutment and second abutment when they are connected to each other.
The first abutment may comprise an internal thread arranged in the first passageway. The internal thread can engage the external thread of the screw such that the first abutment is attached to the screw, before it is inserted into the implant fixture. As a result, the screw as well as the first abutment and the second abutment can be inserted more conveniently into the implant fixture. As the first abutment, the second abutment and, in particular, the screw are of a small size, they are difficult to assembled inside a limited space such as a patient's mouth. It is thus advantageous, to assemble the first abutment and the screw, before they are inserted into the implant fixture.
The second abutment can preferably comprise an internal thread, which can be engaged by the external thread of the screw, additionally or alternatively to the internal thread of the first abutment. The screw can be partially or fully threaded, and preferably has a smaller diameter in the non-threaded section than in the threaded section.
Another advantage of the dental implant is that no glue is required to hold the second abutment in place.
Furthermore the emergence profile of the second abutment can be further adapted to represent a natural tooth. In comparison to the implant fixture, which often has a substantially circular base (or artificial root), the root of a natural tooth is often not circular. With the dental implant according to the invention, the second abutment can be shaped subgingivally to give the impression of a natural tooth. This does not only have esthetical advantages but also diminishes the risk of infections of the gingiva since the accumulation of dental plaque is less important.
In a preferred embodiment, the second abutment is a crown, an artificial tooth or a bridge comprising two or more artificial teeth or a dental prosthesis.
In a preferred embodiment, the second abutment is made of polyetheretherketone (PEEK) or zirconia, in particular yttria-stabilized zirconia (YSZ).
Further details and advantages of the present invention will be apparent from the following detailed description of a not limiting embodiment with reference to the attached drawing, wherein:
The present invention relates to a dental implant with a reduced infection risk of the gingiva in direct contact with the dental abutment.
The present dental implant reduces the risk of infecting the gingiva in direct contact with the dental implant, by rearranging the first abutment and the second abutment such that only one gap is in direct contact with the gingiva. As opposed to known dental implants, the gap between the second abutment and the implant fixture is substantially vertical (angle between 70° and 90°) whereas in the known dental implants the gap is substantially horizontal. Furthermore, as opposed to the prior art dental implants discussed above, the second abutment is not in contact with the intraoral surface of the dental implant.
For a dental implant 2 in
The implant fixture 6 has an axial borehole 14 with an internal thread for receiving a screw 15 in this particular case an M2 screw.
The implant fixture 6 has, on its inner side, a first conical section 16 and a second conical section 18. The first conical section 16 has a conical opening with a downwardly (in direction of the osseous material) inwardly tapered flat. In this particular case with a depth of approximately 0.52 mm, a small diameter of 2.26 mm, which increases to a bigger diameter of 2.46 mm for receiving the first abutment section 20 of the first abutment 4.
The second conical section 18 of the implant fixture has a second conical opening with a downwardly inwardly tapered flat. In this particular case with a depth of 1.37 mm and a bigger diameter of 3.31 mm decreasing to a smaller diameter of 2.82 mm.
The first abutment 4 has a first abutment section 20 (cf.
The second abutment section 26 of the first abutment 4 is downwardly inwardly tapered and engages the second conical section 18.
The first abutment 4 comprises one or more clipping, clamping or gripping elements 21 as a second abutment connector 30 (cf.
The upper abutment connector 22 is arranged in the implant fixture 6 between the first conical section 16 and the second conical section 18 to receive the implant fixture connector 24 of the first abutment 4 such that the first abutment 4 cannot rotate relative to the implant fixture 6. The upper abutment connector 22 is a regular hexagonal prism and has six inward flats of equal size, wherein the parallel opposing flats are spaced at distance of approximately 2.5 mm one from another.
The first abutment 4 comprises an annular, substantially horizontal, surface 28, which is arranged between the second abutment connector 30 and the second abutment section 26. The annular surface 28 comprises an inner diameter corresponding to approximately 2.82 mm and an outer diameter corresponding to approximately 3.31 mm and is parallel with the intraoral surface of the implant fixture 6.
The second abutment connector 30 has six outward flats, wherein the parallel opposing flats are spaced at a distance of approximately 2.49 mm one from the other. The second abutment connector 30 engages the first abutment connector 32 of the second abutment 8. The first abutment connector 32 has 6 inward flats, wherein the distance of the opposing sides is substantially superior to 2.49 mm.
The second abutment 8 has a second exterior surface 36 with an inwardly downwardly tapered flat. The second exterior surface 36 extends along the central axis 34 of the second passageway. This exterior surface 36 partially engages with the second conical section 18 of the implant fixture 6. Additionally, the second abutment 8 has an osseous side, which is pressed against the annular surface 28 of the first abutment 4. The second abutment 8 and the implant fixture are machined very accurately, with tolerances between 5 to 10 μm so that an extremely tight fit can be obtained.
The shapes of the different parts of the dental implant are chosen such that they snugly fit into each other. The first abutment fits on the one hand in the dental fixture and on the other hand in the second abutment. The second abutment fits over the first abutment and into the dental fixture. The exact shape of these components is not crucial, the parts must fit and they must not be able to turn around their vertical axis once they are fitted into/onto each other.
The dental implant as described herein offers the advantage that the second abutment does not “sit” on the implant fixture.
In the present case, the forces from the screw and from chewing are not transferred to the intraoral surface 11 of the implant fixture 6 but they are taken up by the two conical sections 16 and 18 of the implant fixture. The forces per mm2 are thus lower and the stability of the implant is enhanced especially over the longer term.
The surfaces that take up these considerable forces are thus much larger as in the prior dental implants where the second abutment is “sitting” on the implant fixture. Indeed in these prior art dental implants, all the forces are taken up by a relatively small area of the intraoral surface of the implant fixture and the stress exerted par mm2 is thus much larger. In such a construction, the contact area between the second abutment and the intraoral surface of the implant fixture is rather small. Indeed the thickness of the walls of implant fixture and of the walls of the second abutment is very limited. The forces applied to teeth when chewing may be very important and since these forces are applied in a large measure to the rim of the abutment and the rim of the implant fixture, these may break or become damaged.
Furthermore, if the contact surfaces between the second abutment and the implant fixture in these prior art dental implants are not absolutely level, interstices may be created where bacteria may grow and infect the gingival.
Turning now to
| Number | Date | Country | Kind |
|---|---|---|---|
| 92312 | Nov 2013 | LU | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2014/075182 | 11/20/2014 | WO | 00 |
