Abstract:
A dental restoration is provided which includes a base structure and a pre-fabricated over structure which at least partially covers the base structure. An interconnecting material interconnects hardened bite elements of the over structure with the base structure. In accordance with the method of producing a dental restoration, the interconnecting material applied onto the base structure is hardened fully after the over structure has first been applied onto the still malleable interconnecting material.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims foreign priority benefits under 35 U.S.C. §119 from German patent application Ser. No. 103 48 369.1 filed Oct. 17, 2003.  
       TECHNICAL FIELD  
       [0002]     The present invention relates to a dental restoration and a method for producing the dental restoration.  
       BACKGROUND OF THE INVENTION  
       [0003]     A known dental restoration is disclosed in DE 41 33 690. In connection with this known dental restoration, plastic finished partial crowns and bite surfaces are used, which are applied as an integral entirety onto the base structure. After the application of these components onto the base structure, the plastic semi-finished component is hardened via irradiation with ultraviolet, or UV, light, so that a corrected bite surface is thus made available. Such bite surfaces are comparatively soft. At the same time, intensive hand finishing work of such bite surfaces is required to configure the bite surfaces into configurations which simulate the dental structures which are to be restored and the dental restoration which is produced by this approach is heavily dependent upon the capability of the dentist or, as the occasion may be, upon the capability of the dental technician, to produce the desired tooth protuberance shape.  
         [0004]     Moreover, finished elements for the production of dental restorations are already known as is disclosed, for example, in U.S. Pat. No. 6,250,926. The approach disclosed in this publication is suitable for the creation of a dental restoration which is configured by covering a metal frame with an opaque covering and thereafter applying thereon a layer of dentin material ceramic. The dental restoration precisely establishes the shape of the incisal surfaces. The ceramic layer, or coating, which is configured in approximation of the dentin, must have an exact shape so that no orientation errors can arise. Via the application of two layers or coatings, an aesthetic corresponding result can be achieved; however, a decidedly precise handling of the piece is required in order to assuredly prevent the creation of dental positioning errors.  
       OBJECTS AND SUMMARY OF THE INVENTION  
       [0005]     The present invention offers a solution to the challenge of providing a dental restoration, as well as a method of producing a dental restoration, which permits a flexible delivery of dental service via rapid production of the dental restoration without posing special hand finishing requirements.  
         [0006]     The present invention includes a dental restoration having a bite surface of predetermined configuration, which can be produced as a pre-fabricated over structure and which can, therefore, be made available with good quality in a cost-favorable manner.  
         [0007]     The present invention permits one to ensure, in a simple manner, a precise adjustment of the teeth in the occlusion position in that, for example, an orientation can be undertaken in a conventional manner in an articulator. The inner contour of the pre-fabricated over structure is, in this connection, substantially concavely configured and the outer contour of the base is, in a corresponding manner, convexly configured. Even if the relevant contours clearly deviate from, for example, the typical half-spherical and uniform over surface shape of a tooth stump prepared in a conventional manner, there is still a good possibility for precise adjustment at least for the reason that the inventive interconnecting material of this invention covers the gap between the inner contour of the over structure and the outer contour of the base structure.  
         [0008]     If the coating of the interconnecting material amounts to, for example, 0.8 mm or 1 mm, an adjustment of, for example, about 0.5 mm is not a problem, whereby it is preferred that the over structure is, initially, comparatively loosely pressed into position and the precise adjustment is then effected via further “follow up pressing in” of the over structure, with corresponding orientation efforts, onto the bite surfaces.  
         [0009]     In accordance with the present invention, it is also advantageous that one uses the respective antagonistic tooth as the pressure-applying element in the articulator, as, in this manner, an optimization of the dental restoration positioning automatically ensues.  
         [0010]     It is to be understood that also, for example, the Benett angle can be taken into account, and it is also possible, without further effort, to provide coverage for the range of teeth shapes typically arising in a conventional dental practice with a predetermined count or number of preprepared bite surface elements.  
         [0011]     In accordance with the present invention, it is particularly advantageous, moreover, that the interconnecting material, which is preferably comprised of a hardenable plastic which can be hardened in-situ, develops a certain dampening effect so that the wear of the antagonistic teeth is also reduced even in the event that ceramic is deployed for the over structure.  
         [0012]     In accordance with the present invention, it is further particularly advantageous if a base structure covers at least one tooth stump in a unitary manner. It is also possible to so configure the base structure—including via, as the occasion arises, the deployment of an additional frame—such that several tooth stumps are simultaneously covered, whereby a unitary configuration can be realized.  
         [0013]     In accordance with the present invention, the interconnecting material can be allowed to harden in place in a surprisingly simple manner. It is possible to undertake a thermal hardening for the regions of the interconnecting material, which are covered by the base structure. In this connection, a self-hardening plastic material is considered.  
         [0014]     Free lying regions of the interconnecting material that is, side regions of the respective tooth also permit the configuration of a light-hardenable plastic material. Such side regions and, as well, regions of the tooth comprised of aesthetically less relevant bite surfaces themselves, can be covered by the base structure in a comprehensive manner with an opaque-appearing material so that the inventive approach offers an aesthetically satisfactory translucent appearance.  
         [0015]     Surprisingly, despite the use of several different materials, such as the interconnecting material and, as the occasion arises, different light-polymerizable plastic materials for the side region, and despite the different heat expansion coefficients, no edge gaps or cracks are created. By virtue of the coating of, initially, a first interconnecting material for the securement of the base structure on this interconnecting material, the coating of a second interconnecting material for the securement of the over structure on the base structure, and, ultimately, the securement of the over structure itself, respectively comparatively thin coatings are formed which exhibit correspondingly reduced material contraction properties. A time-consuming firing of the assembly can be omitted which favorably benefits a reduction of the cycle time in the dental laboratory.  
         [0016]     A dental restoration produced in accordance with the present invention permits, as well, the polishing thereof in a good manner, whereby the material choice for the over structure is not limited to ceramic material but can, as well, comprise plastic, including plastic in a prefabricated form.  
         [0017]     In accordance with the present invention, it is additionally particularly advantageous if the bite element extends over the entire mastication surface in a crack-free manner. In this manner, a stable restoration as well as a solid surface in the most strongly stressed regions of the restoration is ensured.  
         [0018]     In accordance with the present invention, it is further advantageous that, via the somewhat elastic coating of the additional interconnecting material, fatigue breaks in the over structure occur in a significantly less frequent manner, as the pressure peaks, which typically manifest themselves in the tooth protuberance flanks during mastication, are better captured and compensated by the inventive approach.  
         [0019]     In accordance with the present invention, either comparatively hard plastic or desired ceramic materials can be used for the over structure. Thus, an aluminum oxide ceramic, a zirconium oxide ceramic, or a mixture of these ceramics can be deployed or other oxide ceramics can be deployed without further effort.  
         [0020]     In connection with the production of a dental restoration in accordance with the present invention, the production preferably entails a predetermined excess or spillover of the interconnecting material. Initially, the required preparation is undertaken for the production of an inventive dental restoration. The base structure is formed into a finished condition such as, for example, with a metal coating or formed of complete ceramic or formed in another suitable desired manner. A model is molded of gypsum in a conventional manner. An interconnecting material is applied onto the base structure and, in fact, has a viscosity which still permits deformation while, however, not permitting deformation of the interconnecting material due solely to the force of gravity.  
         [0021]     The over structure is configured with an inner contour which is larger than the outer contour of the base structure but which is, however, compatibly configured therewith. The deposition of a remainder coating of interconnecting material permits application of the over structure onto the base structure and the assembled structure is preferably adjusted in the articulator. The over structure is pressed into the interconnecting material and a precise adjustment is undertaken in the desired manner. A hardening out of the interconnecting material is effected in this position. This can be effected via a self-hardening plastic material which hardens organically or, however, can also be effected by other means such as, for example, via heat polymerizable plastic material having heat applied thereto. The spillover, which occurs laterally of the plastic, is removed preferably before the hardening out. It is also possible to remove a portion of the spillover before the hardening out and to remove the remainder of the spillover after the hardening out.  
         [0022]     The inventive solution provides an improved restoration quality in view of the bite situation despite reduced production costs and despite a shortened improved cycle time. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0023]      FIG. 1  is a perspective view of teeth and showing a pre-prepared tooth stump adapted to receive one embodiment of the dental restoration of the present invention;  
         [0024]      FIG. 2  is an enlarged perspective view of a portion of  FIG. 1 ;  
         [0025]      FIG. 3  is a perspective view of the portion of the one embodiment of the dental restoration shown in  FIG. 2  showing, however, a base structure applied onto the tooth stump;  
         [0026]      FIG. 4  is a perspective view of the dental restoration shown in  FIG. 3  showing, however, a pre-fabricated over structure applied thereunto;  
         [0027]      FIG. 5  is a perspective view of another embodiment of the inventive dental restoration having a modified over structure;  
         [0028]      FIG. 6  is a side elevation sectional view of a representative inventive dental restoration;  
         [0029]      FIG. 7  is a perspective view of a further embodiment of the inventive dental restoration and showing the over structure thereof for a tooth restoration;  
         [0030]      FIG. 8  is a perspective view of the base structure of the further embodiment of the dental restoration shown in  FIG. 7 ;  
         [0031]      FIG. 9  is a perspective view of an additional embodiment of the dental restoration of the present invention and showing the base structure thereof in lieu of the base structure of the further embodiment of the dental restoration shown in  FIG. 8 ; and  
         [0032]      FIG. 10  is an enlarged perspective view of the additional embodiment of the dental restoration shown in  FIG. 9 . 
     
    
     DETAILED DESCRIPTION  
       [0033]      FIG. 1  shows, in a schematic manner, the teeth of a lower jaw, the teeth being indicated generally at  10 . In this illustration a pre-molar V has been prepared such that a tooth stump  12  is available.  
         [0034]     The tooth stump  12  comprises, in a conventional manner, a conventional stump configuration, which can be seen as well in  FIG. 2  in an enlarged view thereof, whereby preparation borders  14  are created in the form of a socket extending in an annularly shaped manner about the tooth stump.  
         [0035]     In accordance with the present invention, a custom dental restoration is to be applied onto the tooth stump  12 . In this connection, as shown  FIG. 3 , a base structure  16  is initially applied onto the tooth stump. The base structure  16  is formed of a metal frame, which has been covered with a not-illustrated opaque-appearing material. The securement thereof follows with a conventional interconnecting material. The base structure  16  has a substantially uniform coating thickness.  
         [0036]     The base structure  16  comprises an outer contour  20  which substantially corresponds to the outer contour of the tooth stump  12  but which, however, is somewhat rounder and larger. The tooth stump  12  is shown in broken lines in  FIG. 3 .  
         [0037]      FIG. 4  shows one embodiment of the dental restoration  22  after the pre-fabricated over structure  24  has been applied onto the base structure  16 . In  FIG. 4 , the base structure  16  is shown in broken lines and it can be seen that the base structure  16  is completely covered by the over structure  24  in this embodiment. The base structure terminates at the preparation borders  14  (compare  FIG. 2 ) and, between the base structure and the over structure, an interconnecting material  26  has been applied (not illustrated in  FIG. 4 ) which fills the entire layer-defining space between the inner contour of the over structure  24  and the outer contour of the base structure  16 .  
         [0038]     In order to prevent included or entrapped air, it is provided that the contact between the interconnecting material  26  and the inner contour of the over structure  24  initially occurs at the highest location  28 . At this location, the thickness of the layer of the deformable interconnecting material is correspondingly relatively great and the shape of interconnecting material is accommodated to the shape of the over structure during the pressing down of the over structure, preferably in the articulator.  
         [0039]     It is to be understood that the exact configuration can be accommodated to a wide range of requirements. Thus, it is also possible to provide a bite element for covering the bite surface and, thereafter, to provide side elements, which may be, as well, pre-prepared components, and which are applied by the pressing thereof into the interconnecting material. This configuration has the advantage that a slight angle accommodation of the bite surface is still possible, whereby it is to be understood that, initially, the angle accommodation should be effected and, thereafter, the side elements can be aligned with the top surface that is, positioned flush with the bite surface element.  
         [0040]      FIG. 5  shows another embodiment of the dental restoration of the present invention wherein the side surfaces  30  of the tooth V are not covered by the ceramic over structure  24 . In this embodiment, a plastic material, preferably, a light-hardenable material  32 , is provided on the side surfaces  30 , this material being hardened after the installation of the over structure and after the conclusion of the top surface preparation that is, the making ready of a flush top surface.  
         [0041]     The deployed interconnecting material between the base structure and the over structure can either be thermally hardenable plastic material, a self-hardening plastic material, or, for example, a dental or tooth cement as well. It is to be understood that the plastic material  32  can, as required, be configured in the same manner that is, for example, such material can also be a thermally hardenable plastic material whose top surface is relatively wear resistant.  
         [0042]      FIG. 6  shows a representative dental restoration of the present invention in cross section. The reference numerals in  FIG. 6  indicate identical elements as are described with respect to like-numbered elements shown in the other figures of the drawings. It is schematically indicated that a further interconnecting material  36  is provided between the tooth stump  12  and the base structure  16 .  
         [0043]     The over structure  24 , in the illustrated embodiment, takes the form of the upper region formed by the bite element  38  as well as a covering element  40  which, in the manner of an apron, extends downwardly. Preferably, this extension of the over structure extends into mesial and distal regions of the tooth, whereat access thereto is significantly limited.  
         [0044]     In accordance with the present invention, it is preferable that the dental restoration is, after its finishing that is, after obtaining a perfect or exact orientation between the base structure  16  and the over structure  24 —accommodated to the teeth structure and, in this connection, that the second interconnecting material  36  is deployed in a conventional manner.  
         [0045]     In a modification of the dental restoration of the present invention, it is provided, in lieu of the base structure, to deploy a special securement material which forms the base structure  16  and onto which the over structure  24  can be directly applied. This approach is especially suitable for small restoration requirements and permits the preparatory removal of the dentin to be limited to the minimum required mass.  
         [0046]     FIGS.  7  to  10  show embodiments of the inventive dental restoration which are suitable for the restoration of a plurality of teeth  10 . As can be seen in  FIG. 7 , a multiple member pre-fabricated over structure  24  of a further embodiment of the dental restoration is illustrated. The over structure  24  comprises three bite elements  42 ,  44 , and  46  corresponding respectively to the teeth IV, V, and VI and are, to this extent, multiple member configuration. An apron  50  extends downwardly on the mesial side of the bite element to communicate with the preparation border that is, along the side flanks of the tooth IV, which is turned toward the tooth III.  
         [0047]     An apron  52  extends along the distal side surface of the tooth VI.  
         [0048]     In the illustrated embodiment, the bite elements  42 ,  44 , and  46  are configured adjacent one another as a unitary component, and the aprons  50  and  52  are likewise configured as a unitary component. It is to be understood, that in lieu of this configuration, a multiple component configuration of the bite elements  42 - 46  is also possible.  
         [0049]     A correspondingly configured base structure  16 , which is suitable for receipt thereon of the over structure  24  in the embodiment shown in  FIG. 7 , is illustrated in  FIG. 8 . This base structure  16  comprises two bowl-shaped recesses  54  and  56  which are downwardly open and can receive correspondingly prepared tooth stumps; in the illustrated embodiment, for example, the tooth stumps of teeth IV and VI. A bridge region  58  is configured between these end regions, the bridge region supporting the bite element  44 .  
         [0050]     Also, in this embodiment, the outer contour of the base structure  16  is compatibly configured with the inner contour of the over structure  24 .  
         [0051]      FIG. 9  illustrates an additional embodiment of the dental restoration of the present invention, showing the base structure  16  thereof. In lieu of the recess  54 , an attachment recess  60  is provided, which is suitable for the receipt therein of an attachment element (not illustrated).  
         [0052]      FIG. 10  shows an enlarged illustration thereof. The attachment recess  60 , which replaces the recess  54  of the  FIG. 8  embodiment, is configured in a conventional manner such that a vertical removal of the attachment element seated therein is possible while, at the same time, ensuring a secure seating of the attachment element received therein. These seating and removal characteristics can be imparted by, for example, providing a corresponding conicity along the vertical axis in the area of the attachment recess  60 . In other words, the recess may be cylindrical or conical, and it should have an axis parallel to the axis of the recess  56 .  
         [0053]     Another suitable desired interconnecting element can be deployed in lieu of the interconnecting material for securing the over structure  24  on the base structure  16  such as, for example, a positive mechanical inter-engagement between the over structure and the base structure.  
         [0054]     While a preferred form of this invention has been described above and shown in the accompanying drawings, it should be understood that applicant does not intend to be limited to the particular details described above and illustrated in the accompanying drawings, but intends to be limited only to the scope of the invention as defined by the following claims. In this regard, the term “means for” as used in the claims is intended to include not only the designs illustrated in the drawings of this application and the equivalent designs discussed in the text, but it is also intended to cover other equivalents now known to those skilled in the art, or those equivalents which may become known to those skilled in the art in the future.