Abstract:
The invention relates to a trans-mucosal component for a dental implant intended to support a prosthetic installation. The trans-mucosal component has been designed for the purpose of improving the quality and stability of the biological adhesion of the junctional epithelium and of the connective tissue and wherein the trans-mucosal component ( 2 ) is provided with a waist-shaped or inwardly narrowed part for reducing the necessary height of the trans-mucosal component and creating a volume for generation of a stabilizing and retentive belt of soft tissue. According to the invention the distance in the longitudinal direction along the contact surface of the waist-shaped or narrowed part should at least correspond to the required, biological width of the adjoining soft tissue.

Description:
PRIORITY INFORMATION  
       [0001]     This application is a continuation of International Application PCT/SE2005/000095, with an international filing date of Jan. 28, 2005, which claims the benefit of Swedish Patent Application No. 0400157-4, filed Jan. 29, 2004, the entire contents of both applications are hereby expressly incorporated by reference herein.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a trans-mucosal component for a dental implant intended to support a prosthetic restoration.  
         [0004]     2. Description of the Related Art  
         [0005]     Trans-mucosal components such as abutments or spacer sleeves as such are already well known in the dental sector and can have one or more portions passing through the gum. In the case where the trans-mucosal component is a separate unit, it is designed to be connected to the bone-anchoring element via a spacer screw or the like. Reference is made to spacer sleeves which are available on the market and which are also described in a large number of different designs in the patent literature.  
         [0006]     The total installation of the implant in the form of bone-anchoring element, trans-mucosal component and attached prosthetic installation is intended to form a dental unit which is well anchored in the jaw bone or gum. For example, it is not desirable for the jaw bone and/or the gum to degenerate or resorb and subside around the trans-mucosal component and the fixture and thus expose, for example, the lower portions of the trans-mucosal component to the soft tissue or the upper part of the fixture. This kind of exposure may cause accumulation of bacteria and gives a less attractive appearance. The object of the invention is to solve this problem by permitting an excellent and durable degree of integration between jaw bone/gum and adjoining portions of the trans-mucosal component or fixture. To avoid bone resorption and subsidence tendencies, the various parts must have extents in the vertical direction (height of the implant and of the trans-mucosal component) which satisfy conditions for epithelial contact and gum contact against the facing portions of the trans-mucosal component, specifically a certain natural, biological width of the adjoining soft tissue should be maintained. Such an object has hitherto been in conflict with the need for a low height of the trans-mucosal component. It is an object of the invention to solve this problem too.  
         [0007]     It is also expedient to achieve an effective coordination of the structures and functions of the trans-mucosal component and of the implant. Thus, for example, it is important to be able to adapt the trans- mucosal component from the point of view of height so that even low trans-mucosal components can now be obtained without risk of bone resorption and subsidence tendencies. There is therefore a need to be able to produce trans-mucosal components with a low height and at the same time satisfy said esthetic requirements.  
       SUMMARY OF THE INVENTION  
       [0008]     According to an embodiment of the invention the trans-mucosal component is provided with a waist-shaped or inwardly narrowed part for reducing the necessary height of the trans- mucosal component and creating a volume for generation of a stabilizing and retentive belt of soft tissue.  
         [0009]     A feature of one aspect invention is that the distance in the longitudinal direction along the contact surface of said waist-shaped or narrowed part at least corresponds to the required width of the adjoining soft tissue. The height reduction is chosen as a function of the size and strength of the remaining implant material in the area between the waist-shaped or inwardly narrowed part and a possible through recess in the implant body. The waist-shaped or inwardly narrowed part is preferably located in its entirety on the trans-mucosal component or the trans-mucosal part of a one-piece implant. In one embodiment, one or both of first and second portions that cooperates with the soft tissue can be provided with an oxide layer, i.e. a titanium oxide layer, in the case where the trans-mucosal component is made of titanium. In a preferred embodiment, a first portion has a cone-shaped (or truncated cone shaped), curved or arcuate first part which can face the epithelium and which can have a length measurement or height measurement of ca. 1 mm. The second portion for cooperation with the connective tissue of the gum can have a curved or arcuate part with a height measurement which can lie in the range of 1.5-1.9 mm, and preferably is ca. 1.7 mm. At its widest cross-sectional area, the trans-mucosal component can have a first diameter of 3-6 mm and, at its waist-shaped or inwardly narrowed area, can have a second diameter of 2-5.5 mm. The lower, medium and higher values within both ranges are in this case set in relation to one another. The waist-shaped or inwardly narrowed part can have a mean depth of 0.2-1.5 mm, preferably 0.5 mm. Further embodiments of the novel arrangement are set out inter alia in the attached patent claims.  
         [0010]     By what has been proposed above, it is possible to provide the necessary gum coverage against the trans-mucosal component or part of a one-piece implant despite the need for a low height of these parts, and without risk of subsidence or resorption. Thus, for example, gum coverages which satisfy the natural (biological) requirements for a certain longitudinal extent of the soft tissue adjoining the trans-mucosal component can be guaranteed without the trans-mucosal component having to have the same height. Instead, the trans-mucosal component is designed with an inwardly narrowed or waist-shaped part which increases the contact distance with the soft tissue compared with a straight longitudinal extent of the contact surface of the trans-mucosal component. The inwardly narrowed or waist-shaped part will have such a size that said contact surface distance at least corresponds to the biologically necessary width of the soft tissue.  
         [0011]     Further measures for increasing integration can be used in combination with said inwardly narrowed or waist- shaped part, for example in the form of growth-stimulating titanium oxide layers, or grooves or depressions in the inwardly narrowed or waist-shaped part.  
         [0012]     Another aspect of the invention can be an implant of the type which comprises a separate trans-mucosal component for passage through soft tissue, which component either can be connected to the bone-anchoring element, or the so-called fixture, of the implant as a separate unit or can also be integrated with the bone-anchoring element to give a so-called one-piece implant. In the case where the trans-mucosal component is a separate unit, it preferably comprises a continuous recess for a screw used to secure the component and, possibly, the prosthetic installation to the bone-anchoring element of the implant. The trans-mucosal component is designed to cooperate with soft tissue, in this case the gum, and on its outside it has a part that can cooperate with the gum. A first portion of this part can cooperate with the epithelium of the gum, while a second portion cooperates with the connective tissue of the gum. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     Some proposed embodiments of the arrangement according to the present invention will be described below with reference to the attached drawings, in which:  
         [0014]      FIG. 1  is a vertical view showing an implant in the form of a bone-anchoring element and an associated trans-mucosal component in the form of a spacer sleeve (a), a one-piece implant in the form of a bone-anchoring element and a spacer trans-mucosal component part integrated with the latter (b), and an implant with a prosthetic installation (c),  
         [0015]      FIG. 2  is a vertical view, enlarged in relation to  FIG. 1 , showing parts of the implant and the spacer sleeve with different designs of the waist-shaped or inwardly narrowed part, and  
         [0016]      FIG. 3  is a vertical view, enlarged in relation to  FIG. 1 , showing parts of the implant and the spacer sleeve where the waist-shaped or inwardly narrowed part of the spacer sleeve is located at a variable height around the spacer sleeve so that it substantially follows the topography of the surrounding gum. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]     In  FIG. 1 , a bone-anchoring element, or so-called fixture, is indicated by  1 . The fixture can be a fixture known per se and will therefore not be described in detail here. The fixture can be made of titanium and is provided with an upper flange  1   a . A trans-mucosal component in the form of a spacer sleeve  2  is assigned to the fixture. The spacer sleeve is intended to support a prosthetic installation  3 , which can be of a kind known per se. The spacer sleeve has an upper, narrowed part  2   a . At the lower parts  2   b  of the spacer sleeve, said spacer sleeve is provided with a waist-shaped or inwardly narrowed, in this case curved, part  2   c . The part  2   c  is located between the upper, narrowed part  2   a  and a lower base portion  2   d  via which the spacer sleeve bears against the fixture, against the upper flange  1   a  thereof. The upper narrowed part  2   a  has a variable thickness around the periphery of the spacer and, at the thicker part, has a height H 1  of in this case ca. 3.5 mm, calculated from the underside of the lower base portion  2   d . At the thinner part, the upper part  2   a  has a height H 2  of in this case ca. 2 mm, calculated from the underside of the base portion  2   d.    
         [0018]     The upper part  2   a  thus has a curved top surface  2   e  which, when the implant and spacer sleeve are in the implanted state in the jaw bone, can follow the top face or outside of the gum or soft tissue at the installation. The waist-shaped or inwardly curved part  2   c  can lie in a plane at right angles to the longitudinal extent of the implant, as is shown in  FIG. 1 , but can also be designed so that it follows a curved top surface  2   e , or shoulder, of the spacer, as is shown in  FIG. 3  below. The spacer sleeve and the fixture can be provided with an internal recess which extends further down in the inside of the fixture  1  and is provided for a fastening screw (not shown) which is intended to hold the fixture, spacer sleeve and, if appropriate, the prosthetic installation together.  
         [0019]     The waist-shaped or inwardly narrowed part  2   c  can be located entirely on the outer surface of the transmucosal component or it can be located so that it is contigous with that part of the trans-mucosal component adjoining the bone anchoring part (1) of the dental implant. In the latter case the surface of the waist-shaped or inwardly narrowed part is then formed by a part of the trans-mucosal component and an annular upper, end surface of the fixture.  
         [0020]      FIG. 1   b  shows a one-piece implant in which the spacer  2  is integrated with the fixture  1 . In this case too, the spacer part  2  of the one-piece implant comprises an inwardly curved or waist-shaped part  2   c  which is designed to cooperate with the surrounding soft tissue, i.e. the gum.  
         [0021]      FIG. 1   c  shows the implant together with a prosthetic restoration in the form of a crown  3 . The gum level  4  has also been indicated in the figure.  
         [0022]      FIG. 2  shows a jaw bone  5  with associated soft tissue or gum  4 . The soft tissue or gum consists of epithelium which is indicated by  4   a  and connective tissue  4   b . The waist-shaped or inwardly curved part  2   c  has a first portion  2   c ′, which in this illustrative embodiment is substantially cone-shaped or formed as a truncated cone. The part  2   c  also has a second portion  2   c ″ which in this illustrative embodiment has a substantially semicircular vertical section (=the section according to  FIG. 2 ). The first portion  2   c ′ has a height H 3  of ca. 0.7 mm, and the second portion  2   c ″ has a height H 4  of in this case ca. 1 mm. The contact distance  4   a ′ of the epithelium against the outer surface of the portion  2   c ′ is of the order of 1 mm. The contact distance of the connective tissue against the second portion  2   c ″ is of the order of 1.5 mm. The height reduction gain for the spacer in the abovementioned case lies within a range of 1-1.5 mm. Despite this, the epithelial contact has a distance of ca. 1 mm, and the connective tissue contact has a distance of ca. 1.7 mm, which means that the required width of the adjoining soft tissue is maintained and a reduced risk of resorption and subsidence tendencies in the jaw bone  5 . A high degree of integration can be obtained between the epithelium  4   a  and the outer surface of the first portion, and between the connective tissue  4   b  and the surface of the second portion  2   c ″. A good esthetic result can also be achieved and maintained in this way.  
         [0023]     In accordance with  FIG. 2 , the lower base portion  2   d  (compare  FIG. 1 ) has a height of ca. 0.2 mm. The upper flange  1   a  (compare  FIG. 1 ) has a height of ca. 0.3 mm. In accordance with  FIG. 2 , good integration is thus obtained between the connective tissue  4   b  and the outer surface of the second portion  2   c ″. The waist-shaped or inwardly curved part thus forms a volume-creating space for the soft tissue, which stabilizes and maintains the soft tissue in the vertical direction. The size of the inwardly curved or waist-shaped part  2   c  is dependent, inter alia, on the remaining material of the implant body between the bottom portion  6  of the waist-shaped part and a possible internal recess in the spacer. The height reduction is calculated in relation to the case where the portions  2   c ′ and  2   c ″ would have outer surfaces which are straight or are parallel to the common longitudinal axis  7  of the spacer and of the implant.  
         [0024]     These straight or parallel outer surfaces would have a height substantially corresponding to the vertical or longitudinal extents of the portions  2   c ′ and  2 ″. Said heights or lengths of the portions will thus be reduced by the heights H 3  and H 4  to establish the height reduction effect.  
         [0025]     The outer surfaces of the portions  2   c ′ and  2   c ″ according to  FIG. 2  can be provided with a titanium oxide layer known per se.  FIGS. 1 and 2  indicate a diameter D for the widest part of the spacer sleeve, and a diameter d for the inwardly curved part. The diameter D can assume values of between 3 and 6 mm, and the diameter d can assume values of between 2 and 5.5 mm. The depth D-d of the inward curve or waist-shaped part can be in the range of 0.2-1.5 mm. In one embodiment, said waist-shaped or inwardly curved part is also provided with grooves or depressions  8 ,  9  extending completely or partially round the periphery of said part  2   c . Said grooves  8  can be located at the lower parts of the sleeve, for example immediately above said lower flange  2   d , as is shown in  FIG. 2   a.    
         [0026]      FIG. 2   b  shows grooves  9  which extend only partially round the periphery and are located higher up on the sleeve. The grooves  8 , 9  can have depths and widths which themselves permit ingrowth of soft tissue and thus increase the stability of the surrounding soft tissue, and they can for example have a width of ca. 100 mm and a depth of ca. 70 mm. In one embodiment, the waist-shaped part  2   c  itself extends round the whole periphery of the spacer sleeve, but the case can also arise in which the inwardly curved part or parts extend (s) only partially round the periphery, for example on those parts which adjoin the teeth upon complete installation of implant, spacer and prosthetic installation. At its upper parts, for example at the flange  1   a , the fixture can be provided with a titanium oxide layer in the same way as the proposed layers of the first and second portions of the waist-shaped or inwardly curved part.  
         [0027]      FIG. 2   c  also shows examples where said grooves  8  curve and are substantially parallel to the curved shoulder  2   e  of the spacer for better adaptation to the topography of the surrounding jaw bone. The inwardly curved or waist-shaped part  2   c  itself can also have a curved, scalloped extent and follows the topography of the soft tissue as is shown in  FIG. 3 . In  FIG. 3   a , it has a substantially constant width round the spacer, whereas in  FIG. 3   b  it is shown with a varying width.  
         [0028]     The invention is not limited to the embodiment described above by way of example, but can be modified within the scope of the attached patent claims and the inventive concept.