Implant part for a dental implant

In a dental implant comprising a mounting post, a crown supported on the mounting post and a spring element supported between the mounting post and the crown so that the crown is movable within limits in axial direction relative to the mounting post against the force of the spring element, the crown is a single part and connected to the mounting post by a form locking connection while the spring element is effective directly between the mounting post and the crown.

BACKGROUND OF THE INVENTION

The invention relates to an implant part for a dental implant with a mounting post and a crown which is displaceable in axial direction within limits against the force of a spring.

Such an implant part for a dental implant is disclosed in DE 101 49 166 C1. The dental implant part disclosed therein comprises a basic carrier implanted into the jaw bone, a hollow cylindrical mounting post and a two-part secondary crown. The mounting post is attached to the basic carrier by means of a central connecting bolt which extends through the hollow cylindrical mounting post. On the mounting post, the two-part secondary crown is disposed. In order to permit a translatory movement in the longitudinal direction of the dental implant, the secondary crown comprises two separate sections which however are interconnected, that is, a support part and a connecting part between which two spring elements are arranged for shock damping. It is the object of this dental implant to provide for a secure and durable connection without detrimentally affecting the damping effects. It is however a disadvantage of this dental implant that the assembly of the two part secondary crown and the spring elements disposed therein is complicated and time consuming.

Furthermore, the central bore in the mounting post reduces its strength whereby the installation of the mounting post on the basic carrier becomes more difficult.

It is the object of the present invention to provide an implant part for a dental implant which is simple and can easily be manufactured and which is also easy to install and provides for a durable and secure connection of the implant parts of the dental implant without detrimentally affecting the resiliency provided by damping springs disposed in the implant.

SUMMARY OF THE INVENTION

In a dental implant part comprising a mounting post, a crown supported on the mounting post and a spring element supported between the mounting post and the crown so that the crown is movable within limits in axial direction relative to the mounting post, the crown is a single part and connected to the mounting post by a form locking connection while the spring element is effective directly between the mounting post and the crown.

The invention will be described below in greater detail with reference to the accompanying drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1is a cross-sectional view along the longitudinal axis2of a composite dental implant1andFIG. 1ais a top view of the corresponding mounting post3. The terms “top” and “bottom” used in the following description refer to the longitudinal axis2of an implant1as shown inFIGS. 1,2,3,4, and5installed in a lower jaw bone.

The mounting post3includes in its top area a connecting element7aand in the area below the connecting element7a, it has a cylindrical portion3a, which, in a downward direction, becomes narrower forming a truncated coneshaped area3b. The rotational symmetrical axis of the mounting post3extends co-axially with the longitudinal axis2of the implant1and of the tooth when installed in the jaw bone.

On the mounting post3, a crown4is disposed which is adapted to receive an artificial tooth or a prosthesis, neither one of which is shown herein. The crown4is disposed on the mounting post3and is adapted to receive and carry the artificial tooth structure or a prosthesis. The crown4has a double-truncated cone-shape with a lower truncated cone section4awhose cross-section becomes smaller in downward direction along the longitudinal axis2and which is axially substantially shorter than the upper truncated cone section4bwhose cross-section becomes smaller in the upward direction. In the interior of the crown4, there is a central cavity4d,which in the present case is formed by a bore4dwhich is co-axial with the longitudinal axis2.

For interconnecting the crown4and the mounting post3, a form-locking connection7is provided which inFIG. 1is in the form of a bayonet lock. To this end, the mounting post3is cylindrical at its upper end and has a diameter which is somewhat smaller than the diameter of the central cavity4din the crown4, so that the crown is longitudinally movable relative to the mounting post3in the direction of the axis2. At the cylindrical upper end of the mounting post3, there is a first connecting element7awhich is formed by two opposite rectangular projections with recesses extending radially from opposite sides into the projections. The top view ofFIG. 1ashows the rectangular projections having straight outer edges, but the outer edges may be rounded that is the projections may be circular sections.

The first connecting element7aof the mounting post can be brought into engagement with a second connecting element7bof the crown which second connecting element is formed by an inner annular recess in the lower part of the crown4. For the assembly of the mounting post3and the crown4, the annular inwardly extending projection7bof the crown4, which is disposed below the first connecting element7a, includes two openings corresponding to the rectangular projections of the first connecting element7aof the mounting post3and into which the rectangular projections7bextend. The height of the annular recess in the direction of the longitudinal axis2is at the openings so large that the rectangular projections of the first connecting element7acan be rotated into the annular recesses. The height then becomes smaller in the direction of rotation in a ramp-like fashion up to an engagement recess, which, in the direction of rotation, is disposed in front of the next opening and serves as rotational locking structure. The opening has such a height in the direction of the longitudinal axis2, that in the assembled state, limited movement of the crown4in axial direction with respect to the mounting post3is possible. The axial motion clearance depends on the height difference between the second connecting element7bof the crown4and the first connecting element7aof the mounting post3and is preferably 10 to 100 micrometer.

In the cylindrical space between the mounting post3and the crown4which is present in the assembled state a pre-tensioned spring element,6is disposed in the form of a spiral compression spring. The spring element6abuts a first engagement surface6aat the upper end of the mounting post6and a second engagement surface6bat the upper end of the central cavity4dof the crown4so that the crown4is biased away from the mounting post3in the direction of the longitudinal axis2when it is not loaded. For the adjustment of the spring force spacer elements6cmay be placed between the spring element6and the engagement surfaces6aand6b.

At its lower end, the crown4includes a transition bore4cso that, in an assembled state of the tooth implant part1, the crown4extends over the cylindrical area3aof the mounting post3. In a non-loaded state, that is when no outer forces act on the tooth implant in the direction of the axis2, the lower conical part4aof the crown4and the frustroconical part3bof the mounting post3are essentially in alignment so that the transition area5is sealed and food rests or cement used for mounting the prosthesis or for forming the crown cannot enter the interior of the implant part1and, as a result, block the movement of the crown4relative to the mounting post3.

For installation, the assembled implant can be threaded into the basic carrier (not shown), which has been implanted into the jaw bone, via an inner cone wrench which is placed onto the crown4and pressed downward to engage the implant part1so as to permit its rotation. The crown may also be provided at its outside with grooves or with flattened areas so that it can be engaged by a suitable tool in a form-locking manner for example by way of a double edge or a hexagonal socket wrench.

It is a particular advantage that this implant1is easy to install and that the crown4, mounted by a bayonet locking structure, can easily be removed from the mounting post in a non-destructive manner for control or repair purposes.

FIG. 2shows in a cross-sectional view taken along the longitudinal axis2an assembled implant part1with a thread joint and,

FIG. 2ais a top view of the respective mounting post3. This implant part1is to a large extent identical with the embodiment shown inFIG. 1so that only those elements will be described below which are different from the embodiment shown inFIG. 1.

In this embodiment, the mounting post3includes above its cylindrical section3aan outer cylinder9with an annular groove10and an inner cylinder11at the upper end of which a first connecting element72of the mounting post3is arranged.

The outer cylinder9extends co-axially with the longitudinal axis2and has a slightly smaller diameter than the cylindrical area3aof the mounting post3. It extends movably into a corresponding bore in the lower part of the crown4. The outer cylinder9as well as the corresponding bore of the crown4have a smaller height than the central cavity4dof the crown. The outer cylinder9is shorter than the corresponding bore in the crown4by an amount corresponding to the desired length of axial freedom of movement between the mounting post3and the crown4.

The inner cylinder11extends co-axially with the longitudinal axis and projects into the central cavity4dof the crown4. The diameter of the inner cylinder11is so selected that a spring element6can be accommodated between the outer surface of the inner cylinder11and the inner surface of the central cavity4dcorresponding to the spring element shown inFIG. 1.

For a secure engagement of one end of the spring element6with the mounting post3, the first support surface6afor the spring element6is disposed in the annular groove10which is formed axially into the outer cylinder9around the inner cylinder11. The second support surface6bfor the spring6is formed by an upper shoulder of the central cavity4din the crown4.

In order to join the mounting post3and the crown4in a form-locking manner, an additional upwardly extending cylindrical connecting cavity extends co-axially with the longitudinal axis2upwardly into the crown4with a diameter which is slightly larger than that of the inner cylinder11. The lower area of the connecting cavity includes an internal thread72b, which forms a post connecting structure with the crown4. The internal thread72bfits with a corresponding outer thread72aat the upper end of the inner cylinder11which represents the other part of the connecting structure on the mounting post3. The crown4is mounted onto the mounting post3by threading the inner cylinder11with the outer thread72ainto the inner thread72bof the crown4until the two threads are out of engagement. In order to facilitate this procedure and, additionally, the desired axial movement of the crown relative to the mounting post3the area of the connecting cavity above the internal thread7bis as high as the outer thread plus the desired length of freedom of movement of the crown4.

Further the connecting cavity includes at its top a semicircular recess into which a corresponding semicircular projection at the upper end of the inner cylinder11may extend. Together they form a rotational locking structure8. They have a height which permits the desired movement of the crown4with respect to the mounting post3in the direction of the longitudinal axis2including the movement clearance. By downward pressing the screwed-in crown4onto the mounting post3, the semi-circular recess comes into form-locking engagement with the semi-circular inner cylinder part so that the implant part1can be screwed into the basis carrier which has already been implanted into the jaw bone.

A particular advantage of the implant part1with the thread connection is that it is not only easy to install but that the crown4can easily be removed from the mounting post3for control or repair purposes without destroying it. Furthermore, the inner cylinder11provides for increased stability of the mounting post3and provides good guidance for the spring element6for which also more space in the direction of the longitudinal axis2is available.

FIG. 3is a cross-sectional view along the longitudinal axis2of a composite tooth implant with an implant part1with a snap-in locking structure including an outer engagement member disposed on the mounting post.FIG. 3ais a top view of the respective mounting post. This implant part1differs from the embodiments shown inFIGS. 1 and 2by the type of the connection which will be described below:

At its upper end, the mounting post3is provided with a hexagonal end post15which, starting at the cylindrical area3aof the mounting post3, becomes uniformly smaller in cross-section. The end post15however may have a shape other than hexagonal: it may have, for example, a triangular or a multi-angular cross-section. At the upper end of the hexagonal end post15engagement members73aare provided which extend outwardly beyond the outer surfaces of the post15and have a lower horizontal engagement edge and an upper inclined ramp surface. A bore16is provided in the upper end of the hexagonal end post15which extends about halfway down the height of the hexagonal end post15. The upper ends of the hexagonal end post15are provided with cut-outs12, which essentially extend down almost to the bottom wall of the bore16so as to form six post legs. The bore walls sections separated by the cut-outs12provide for resiliency of the legs of the hexagonal end post15which form elastic latching elements.

The central cavity4dof the crown4has at the bottom end a transition bore section4cand above the transition bore section4three areas: A lower area of an upwardly narrowing hexagonal cross-section corresponding to the shape of the hexagonal end post15; an intermediate area with inner engagement structures73b, which have a horizontal engagement shoulder on which the elastic latch elements73aof the legs of the mounting end post15snap out so as to provide for a secure connection between the mounting post3and the crown4; and a third upper area of the central cavity4dof the crown4comprising a cylindrical bore for receiving the spring element6, which is disposed in the space between the central cavity4dof the crown and the bore16in the mounting post3.

In order to facilitate axial movement of the crown4relative to the mounting post3when the implant part1is assembled, the height of the transition bore4cand the lower and intermediate area of the central cavity4dof the crown4with respect to the height of the hexagonal end post15is so selected that the desired amount of movement can be accommodated.

In this embodiment, it is particularly advantageous that the implant part can be easily and rapidly assembled. The hexagonal end post15also prevents sideward movement of the crown4on the mounting post3and at the same time, prevents rotation of the crown4.

FIG. 4is a cross-sectional view taken along the longitudinal axis2of a composite implant part, with a snap-lock latching mechanism between the crown4and the mounting post3, andFIG. 4ais a top view of the respective mounting post3. This implant part1differs from those ofFIGS. 1 to 3by the type of connection which will be described below.

The mounting post3comprises in the upper area thereof a rectangular end post17which, at its lower end adjacent the cylindrical section3aof the mounting post3, has two opposite recesses18whose upper surface areas form the horizontal engagement shoulder74afor the snap connection. The side surfaces19of the more inwardly disposed sides of the rectangular post17are partially inclined inwardly toward the top of the mounting post in order to facilitate the engagement of the snap connection. The upper end of the rectangular end post17includes a bore16for receiving and supporting the spring element6.

The central cavity4dof the crown4includes above the transition bore4ctwo areas; the lower area comprises a rectangular cavity section13which corresponds in shape to the rectangular end post17. At the lower end, the cavity wall is provided with opposite engagement elements74beach having an upper horizontal engagement edge and a lower ramp area which is inclined upwardly-inwardly. The second, upper area of the central cavity4dof the crown is a cylindrical bore for receiving the other end of the spring element6, which is disposed in the space formed by the center cavity4dof the crown and the bore16in the mounting post3.

In order to facilitate movement of the crown4relative to the mounting post2in the direction of the longitudinal axis2when the implant part1is assembled the heights of the transition bore4cand the rectangular cavity section13of the central cavity4dof the crown with respect to the heights of the respective opposite surfaces of the rectangular end post17are so selected that the desired movement can be accommodated.

In this embodiment, it is particularly advantageous that the implant part can be rapidly assembled in a simple manner. Furthermore, the rectangular end post17prevents sideward movement of the crown4on the mounting post3and at the same time prevents rotation of the crown4.

FIG. 5is a cross-sectional view taken along the longitudinal axis2of a composite implant part1with sidewardly removable locking members andFIG. 5ais a top view of the respective mounting post.

The form-locking connection7between the mounting post3and the crown4is realized by a sidewardly insertable mounting element14. The connecting structure of the mounting post3is formed by the rectangular end post75awhich extends from the cylindrical area3aof the mounting post3and has a rectangular passage75cextending through the end post75atransverse to the longitudinal axis2.

The crown4is provided on an outer surface area at the upper truncated cone section4bthereof with a flattened area72binto which a rectangular side cavity13is formed which extends into the interior of the crown4and beyond the central cavity4dof the crown4. This rectangular side cavity13is, in the assembled state of the implant part1with the rectangular passage75cof the mounting end post75a.

The crown4and the mounting post3are interconnected by the safety element14, which has essentially an elongated rectangular shape with a length so that, in the assembled state of the implant part1, it extends through the rectangular side cavity13of the crown4and the rectangular opening75cin the rectangular end post75aup to the inner end of the rectangular side cavity13. The height and width of the safety element14are so selected that it fits snugly into the rectangular cavity13of the crown4and a sideward movement of the crown4on the post3is prevented. The end of the safety element14which, in the assembled state of the implant part1, faces outwardly complements the missing part of the crown4so that the crown's truncated cone-shape is re-established when the safety element14is inserted for locking the crown4to the mounting post3.

In order to prevent an unintended release of the crown4from the mounting post3, the safety element14includes at its bottom side a spring leaf14awhich is firmly connected at one end thereof to the safety element14and whose free end extend towards the outside wall of the crown4. The leaf spring14aextends in a released state with its free end so far beyond the underside of the safety element14that its free end comes into engagement with the top edge of the central cavity4dof the crown at the rectangular opening75cwhen the implant part1is assembled. In order to facilitate the insertion of the safety element14into the side cavity13of the crown4and through the rectangular opening75cof the end post75a, the leaf spring14amay retract into a cut out in the underside of the safety slide element14.

In order to support the crown4movably in the longitudinal direction2of the implant part1with respect to the mounting post3, the rectangular opening75cof the rectangular end post75ais higher by the desired amount of movability between the crown4and the mounting post3than the safety element14.

The first engagement surface6aof the spring element6on the mounting post3is formed by the top side of the rectangular end post75a, the second engagement surface6bis formed by the top end of the central cavity of the crown4. When the tooth implant is not loaded, the top side of the safety element14is pressed against the top side of the opening75cof the rectangular end post75a.

It is a particular advantage of the arrangement according to the invention that no central inner screw arrangement is needed for the connection of the mounting post and the crown and the spring element can be disposed directly between the mounting post and the crown. A division of the crown into two parts is therefore not necessary whereby the assembly of the implant part consisting of mounting post, crown and spring element is simplified and the mounting post can be more massive and stronger. As a result of this increased stability and the prevention of relative rotation between mounting post and crown the assembled implant part1can be screwed by a tool engaging the crown such as two edge-, a hexagonal or an inner cone wrench, in a simple manner into the basic carrier implanted into the jaw bone.

With the smooth jointure between the crown and the mounting post in the lower area of the crown furthermore, the penetration of cement is prevented by which a prosthesis or a cover is mounted onto the crown. As a result, the axial movability of the crown on the mounting post is ensured; the chances of a blockage are minimized.