Abstract:
A procedure for fabricating an individual abutment for a dental prosthesis for an implant anchored in an area of the jaw with an implant attachment running on the abutment side, using a working model molded by the jaw area equipped with the implant. The sulcus area of the gum uncovered above the implant and shaped by a sulcus-former extending from the implant attachment is reproduced in the working model. The abutment has a sulcus section running within the sulcus area and an adjoining head section to admit a part of a dental prosthesis. The sulcus area of the working model having an auxiliary implant attachment corresponding to the implant attachment is measured, and a sulcus section model determined with a circumferential surface and a de-facto sulcus line limiting it on the implant side.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a procedure for fabricating an individual abutment meant for a dental prosthesis for use in an implant anchored in an area of the jaw with an implant attachment on which the abutment is fixed or to which the abutment is aligned, using a working model molded by the jaw area equipped with the implant, with the sulcus area of the gum uncovered above the implant and shaped by a sulcus-former extending from the implant attachment being reproduced in the working model and with the abutment to be fabricated comprising a sulcus section running within the sulcus area and an adjoining head section to admit a part of a dental prosthesis, which if necessary is an integral component of the head section. 
     From EP-B-0 891 163 and EP-B-1 518 511, a dental prosthesis is known in which the abutment connecting an implant with a crown, which also can be designated as a post, is individually configured so that all the surfaces of the abutment projecting above the gum lines have a geometric course that corresponds to the surface of the externally visible part of the dental prosthesis, i.e., customarily a crown, though with smaller dimensions, since the abutment is provided with a cap or a facing. 
     With an implant-supported dental prosthesis according to EP-B-1 062 916, a working model of a jaw area to be equipped with a prosthesis is fabricated and, into the working model, a manipulation implant is inserted with auxiliary elements that then are scanned to determine base data that are used to determine interpolation data for a framework to be applied to the abutment or a superstructure surrounding the framework. For this, the abutment is individually configured, with an abutment blank to be processed being used, which can be adapted to what is needed with the least processing expense. 
     A dental prosthesis system is known from DE-B-10 2007 018 453. This comprises a dental implant and a superstructure built on it, which has a mounting post for mechanical support that can be individually produced. 
     The subject of WO-A-2004/060197 is a procedure for automatic generation of a dental superstructure for connecting with an implant. An inserted abutment can be optimized for shoulder width, stump height and turning angle. 
     Even if, as per the prior art, individually configured abutments are known, standard geometries are used for the section running below the gum line, without making allowance for the individual particulars of the jaw and gum area, in to which the dental prosthesis and thus the abutment are inserted. 
     SUMMARY OF THE INVENTION 
     The task that is the basis for the present invention is to develop a procedure of the type previously described so that the abutment is geometrically adapted or displayed in the area of it running below the gum line to the contour of the gum. It is especially to be ensured that the abutment and the gum are to be fitted so that deposits are avoided and the gum suffers no inflammation. The fabrication should also be simplified. 
     To solve the problem, in essence the invention makes provision that the sulcus area of the working model having an auxiliary implant attachment corresponding to the implant attachment is measured; that on the basis of the data obtained by the measurement, a sulcus section model is determined with a circumferential surface and a de-facto sulcus line limiting it on the implant side; that missing data between the determined auxiliary implant attachment or a zero-point area related to this and the de-facto sulcus line or an auxiliary sulcus line determined by interactive alteration of the de-facto sulcus line are supplemented by library data which are assigned to the sulcus-former; and that the data of the sulcus section model are used, while allowing for the de-facto sulcus line or the auxiliary sulcus line and the library data to produce the sulcus section. 
     According to the invention, especially through scanning, the sulcus area of the working model is measured so that then the measured data, thus point clusters, are converted into a triangulated surface model, so that the sulcus section model or sections of this is or are graphically represented. For this, individual points determined from the data are connected, and areas in which measurement data are missing are supplemented while making allowance for the measurement data determined or data from a library are allowed for, which fundamentally are assigned to the sulcus-former. 
     To make possible a clear allocation between the measured data (surface data) of the sulcus area and the library data of the sulcus-former or other required library data for producing the sulcus area of the abutment, first a so-called laboratory implant—also designated as an auxiliary implant—is inserted into the model, which from position and geometry corresponds to that of the implant in the jaw, to the extent the area is affected, which is necessary for positioning and attaching the abutment. Then the laboratory implant is equipped with an auxiliary element (measured element), which has an unambiguous geometric assignment to the laboratory implant and thus to the implant, ensuring that the orientation and position of the laboratory implant, and thus of the implant, are ensured in unambiguous fashion. The auxiliary element and the working model are measured and scanned jointly. It is not necessary that simultaneously the entire sulcus area be measured, to determine data for the sulcus section and thus the sulcus section model to be produced. Rather, for determination of the sulcus section model, beforehand the auxiliary element can be removed, so that the auxiliary element does not put parts of the sulcus area in shadow. 
     Since the sulcus-former inserted into the jaw also has a clear orientation and position vis-à-vis the implant, consequently the data of the sulcus-former stored in a library are to be clearly assigned to the measured data. Thus, all data are represented in a common coordinate system. 
     If necessary the type of implant used can be derived from the auxiliary element. 
     The sulcus line itself runs on the circumferential surface of the sulcus-former. For this, measurement data running on the implant side are determined as the initial measurement points that are connected with each other, with the de-facto sulcus line pre-set via the connection line. In determining the de-facto sulcus line, the library data on the sulcus-former are taken into account. The data are altered, either to automatically or interactively determine the auxiliary sulcus line, if measurement data would yield measured points that lie between the auxiliary implant attachment and the zero point area or even below the auxiliary implant attachment, with a shift of the de-facto sulcus line occurring on the circumferential surface of the sulcus-former to at least the zero point area like the zero point line or plane. 
     For the invention it is essential that the de-facto sulcus line, thus the lower limit line of the sulcus section model determined by the measurement, can be used as the initial point for individual configuration of the sulcus area of the abutment to be produced. The de-facto sulcus line basically runs above the zero point area which can be a surface or line, between which and the implant inserted in the jaw area, i.e. the implant attachment, which for example can be an implant shoulder. The abutment is not individually configured in this implant section, whose geometry is preset in fixed fashion and is designed to the structure of the implant, to ensure that the abutment—regardless of its otherwise individual configuration—is able to be inserted and attached into or onto the implant with an exact fit. 
     The zero point area of the abutment can be the underside of the abutment itself. However, customarily the implant section is cylindrical or tapered, with additional positioning elements provided on the end side like a hexagon, octagon, rhombus or an oval cylinder, which engage in form-locking fashion into a geometrically adapted section of the implant, securing it against twisting. 
     The jaw area is shaped when the inserted implant has grown in, the gum over the implant has been removed, and a sulcus-former is attached on the implant. After the sulcus-former has been attached on the implant over a preset time such as two weeks, it is removed, thus to produce a negative impression on the basis of which the working model is produced, which consequently represents the situation in the patient&#39;s jaw, in which the dental prosthesis is to be integrated. 
     From the measured or scanned data, not merely a de-facto sulcus line results, but also an emergence line that describes the gum line above which the abutment projects. Like the de-facto sulcus line, the emergence line can also be individually altered, to produce the sulcus section of the abutment based on the data that then are available. 
     The emergence line, which in actuality is a profile line, is determined directly from the measured or scanned data, whereby likewise—as with the de-facto sulcus line—individual secondary measurement points are determined from measurement data, that, connected with each other, define the emergence line. After the emergence line has been appropriately determined, its course can automatically be altered, especially shifted overall on the circumferential side by an interval d such as d≦0.5 mm in the direction of the implant. It is just as possible to shift it in the opposite direction. 
     If the de-facto sulcus line lies on the circumferential surface of the sulcus-former, the data of the de-facto sulcus line consequently are adjusted to those of the sulcus-former, then the emergence line runs outside the sulcus-former. 
     To form the envelopes of the sulcus section model, the first and second points which are equal in number are then connected with each other, without them crossing. The course of the connection lines is thus determined via the measured data of the sulcus area. The lines forming the envelopes then can be altered automatically or interactively in their course. 
     If the de-facto sulcus line is altered, then as a result of this the library share of the data that correspond to the sulcus-former, is increased. Especially if the sulcus line is elevated, i.e. shifted in the direction of the emergence line, the library share of the sulcus-former data is correspondingly increased. 
     Provision is especially made that the data determined by measurement of the sulcus area of the working model, and thus the surface model derived from the data in the form of the sulcus section model, are interactively altered so that the entire outer surface of the sulcus section model runs in radially convex and axially convex fashion or in a straight line. This ensures that in the abutment produced by the CAD-CAM technique, and particularly in its sulcus area, deposits do not build up between it and the gum. 
     Provision is especially made that the model is radially stretched, ensuring that the sulcus area of the abutment fully abuts on the gum. Consequently, an erasure of the gum mask is simulated, as occurs with the customary technique. Additionally, the data can be altered for smoothing the exterior surface of the sulcus area. 
     If measured data are present that lie below the zero point area, then according to the invention, as mentioned, provision is made that the de-facto sulcus line shifts in the direction of the zero point area, so that as a result, it is always ensured that the section of the abutment on the side of the implant is exactly adapted geometrically to the inserted implant. 
     Missing measured data between the de-facto sulcus line or the automatically or interactively altered de-facto sulcus line, which is designated as the auxiliary sulcus line, and the zero point area of the sulcus section are then supplemented by the data of the sulcus-former. 
     According to the invention, the sulcus area of the abutment is individually configured, thus the part of the abutment is limited toward the upper part, i.e. the head section, by the emergence line or the emergence profile and toward the lower part by the zero point area. 
     The sulcus section of the abutment can be exactly adjusted automatically corresponding to the measured sulcus area in the working model and smoothed to the required extent. Especially provision can be made for an automatic smoothing while allowing for the emergence line or the emergence profile and of the zero point area. 
     The geometric data determined from the measured data can be automatically altered, which represent the sulcus area in such a way that a completely convex geometry results with a simultaneous smoothing of the surface. 
     Additionally the sulcus area can be expanded or enlarged. This can be done particularly in the area of the emergence line, so that the abutment produced by the CAD-CAM technique fully adjoins the gum. 
     Missing data are supplemented by those of the sulcus-former used, i.e., its geometric information and circumferential geometry data are included. If—as in the emergence profile area—there is no adaptation to the sulcus-former, the missing data are supplemented via suitable algorithms. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further particulars, advantages and features of the invention are drawn not merely from the claims, and the features to be gleaned from then—by themselves and/or in combination—, but also from the following description of an embodiment example shown in the drawings. 
       Shown are: 
         FIG. 1 : a dental prosthesis; 
         FIG. 2 : a working model; 
         FIG. 3 : an image with measurement points, determined by scanning a gap in the working model in  FIG. 2 ; 
         FIG. 4 : another depiction of the gap in the working model as per  FIG. 2  with a superimposed sulcus-former; 
         FIG. 5 : a depiction of measurement data with superimposed sulcus-former; and 
         FIG. 6 : a depiction corresponding to  FIG. 5  with individually altered data. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows, purely in principle, a dental prosthesis  10  which is to replace a front tooth. The dental prosthesis  10  consists of an implant  12 , preferably capable of being screwed in, in the area of the jaw in which the front tooth is to be replaced; an abutment  14 , that can be inserted in form-locked and non-twisting fashion into implant  12 , and is able to be connected with it; and a faced crown  16 . Regarding the principal design of dental prosthesis  10 , reference is made however to structures sufficiently known, so no need exists for more comprehensive explanations. Therefore also, no details are provided either regarding a positioning device or positioning elements which are provided in both the implant  12  and the abutment  14 . 
     In fact from the principle depiction of  FIG. 1 , a hexagon  19  is perceptible as the positioning device, which engages into a receptacle with an appropriately adapted geometry in implant  12 . 
     The implant  12  has a shoulder  20  on which an encircling band  22  of abutment  14  sits when properly positioned. Abutment  14  itself is connected with implant  12  by means of a screwed element that is not depicted in greater detail and which penetrates implant  14  in the direction of the longer axis. For this, implant  12  has a blind hole with an appropriate interior threading, this not able to be gleaned from the drawing. 
     According to the invention, abutment  14  is individually configured, at least in a so-called sulcus section  24 , which is surrounded by the gum when abutment  14  is secured. On the implant side, sulcus section  24  makes a transition into an implant section  25 , the geometry of which is preset by the implant inserted in the jaw, thus independent of the otherwise individual configuration of abutment  14 . Additionally, on the head side, sulcus section  24  makes a transition into a head section  27 , which is surrounded by the facing crown  16 . 
     The dividing line between head section  27  and sulcus section  24  is delimited by a so-called emergence line  146 . Emergence line  146  is directed to the upper edge of the gum space, above which the head section  27  of abutment  14  projects. If necessary, after it is determined, emergence line  146  can be shifted in the direction of implant  12  or head section  27 . 
     A so-called zero point area divides sulcus section  24  from implant section  25 . In the graphic depiction of  FIG. 1 , the band  22  runs in the zero point area. To appropriately configure sulcus section  24  to the surrounding conditions in the jaw in which dental prosthesis  10  is inserted, the procedure according to the invention is as follows. 
     In a known manner, first after removal of the tooth to be replaced, an implant is inserted into the patient&#39;s jawbone. After the implant has grown into the bone, the gum tissue covering the implant is opened, to insert a so-called sulcus-former. After this has been in the gap in the teeth over a time that complies with an experience value, such as two weeks, it is removed, to produce by modeling of the jaw in this area a negative impression, from which a working model  26  is produced that reflects the situation in the patient&#39;s jaw in which the dental prosthesis is inserted. 
     In  FIG. 2 , the working model  26  has two gaps  28 ,  30  into which a dental prosthesis is integrated. Additionally, working model  26  is processed by a dental technician to the point where so-called laboratory implants  32 ,  34  are inserted in working model  26 , which are identical in orientation and position to the implants that are used in the jaw. The area of the laboratory implants  32 ,  34  on which an abutment sits or to which the abutment assumes a fixed preset position, which is designated by the implant as an implant attachment and by the laboratory implant as an auxiliary implant attachment, is the visible outer surface of the implant or of the laboratory implant. 
     Then the gaps  28 ,  30  are measured, to determine data for the area of the abutment that runs inside the sulcus area. This is explained purely by way of example using  FIGS. 3 to 5 . 
     Thus, for example, the gap  28  with a realistically reproduced area  36  that surrounds gap  28  in the embodiment example, is scanned or measured by some other suitable procedure. In a first measurement step, an auxiliary element—also called a scanning aid—is inserted into laboratory implant  32 , the position and orientation of which coincides with the realistic implant that is inserted into the jawbone, which [auxiliary element] has a defined orientation to the auxiliary implant  32 , so that the measured data reflect the position and orientation of the implant in the jaw area. 
     Since the sulcus-fomer used in the implant also has a clear orientation and position vis-à-vis the implant, consequently the sulcus-former data stored in a library can be clearly related to the laboratory implant data and thus that of the real implant, so that as a result, measured data of the sulcus area of the imprint, i.e. of area  36 , which runs between the upper side or shoulder  40  of laboratory implant  32 , i.e. the auxiliary implant attachment, and the upper limit of the area  36  surrounding gap  28 , can be unambiguously correlated to the implant in terms of coordinates. The data on the implant, the sulcus-former and that of the sulcus area of the working model, and thus on the gum that surrounds the gap, can be depicted consequently in a common coordinate system, the origin of which is designated in  FIG. 4  as zero point  43 . 
     To be able without shadings to measure, when scanning sulcus area  38  of working model  26 , i.e. of the area that surrounds gap  28 , that extends between the shoulder  40  designated as an auxiliary implant projection, to upper edge  42  of area  36 , usually the auxiliary element is removed, after this has been previously measured with proper positioning in the laboratory implant  32  together with the relevant area of working model  26 , i.e. at least with coverage of the auxiliary implant projection and of area  26  with the upper edge  42  that delimits it. 
     The point clusters determined by measurement such as scanning are then converted into graphically depicted surface data as is shown in  FIGS. 3 and 4 . The measurement data that have been obtained by scanning gap  28 , are delimited by two lines characteristic of the gap, that are determined from the measurement data. 
     As  FIG. 4  shows, a sulcus line  44  and an emergence profile line  46  are generated from the measured data. Emergence profile line  46  is determined by the upper edge of the area  36  surrounding gap  28 . Correspondingly, from the lower measured data, i.e. those situated closest in relation to laboratory implant  32 , the sulcus line  44  is determined. Both sulcus line  44  and emergence profile line  46  are formed from measurement points  48 ,  50  or  52 ,  54  determined from the measured data and connected with each other. Measurement points  48 ,  50  of sulcus line  44  are designated as the first measured points, and measured points  52 ,  54  of emergence profile line  46  as the second measured points. The first measured points  48 ,  50  and the sections  56 ,  58  that join them to form sulcus line  44  are modified that in terms of the data they come to lie on the circumferential surface of the sulcus-former, the data for which are stored in a library. This is principally made clear by  FIG. 3 . One can recognize sulcus line  44 , which lies on the circumferential surface  60  of a depicted sulcus-former  62 . 
     The corresponding sulcus-former  62  is also depicted in  FIGS. 5 and 6 . The emergence profile line  46 , which follows the height profile of the upper gum line into which the dental prosthesis is inserted, and thus the edge  42  in working model  26 , runs on the other hand at a distance to the sulcus-former  62 . Missing measured data are determined while taking into account adjoining measured data and with a suitable algorithm as a basis. In regard to sulcus line  44 , missing data are supplemented by surface data of sulcus-former  62 . 
     Sulcus line  44  is determined by data that are still determined from scanning of area  36  that surrounds gap  28 . Normally sulcus line  44  runs at a distance to zero point line  67  drawn in  FIG. 6 , below which the abutment to be produced must reveal fixed, preset geometry values in order to be inserted with a precise fit into the implant. Zero point  67  would correspond to band  22  in  FIG. 1 . Consequently, from band  22  to the lower end  66  of abutment  14 , recourse was had to library data that are not altered, through which it is ensured that notwithstanding the individual configuration of sulcus area  24  of abutment  14 , the abutment  14  is inserted as per position and with exact fit into implant  12 . 
     The data missing between sulcus line  44  and zero point line  67  are then supplemented by data of sulcus-former  62  stored in the library. 
     As a comparison between  FIGS. 5 and 6  makes clear, a possibility exists to shift sulcus line  44  individually. As per  FIG. 6 , a section of sulcus line  44  in  FIG. 5  has been shifted in the direction of emergence profile line  46 . Sulcus line  66  thus altered nonetheless continues to run on the surface of sulcus-former  62 . 
     From  FIGS. 5 and 6  it also becomes clear that sulcus-former  62  runs in its upper area at a distance to a an area  68  designated in dentistry terms in the actual sense as a sulcus or to the area  36  surrounding gap  28  in the embodiment example of  FIG. 2 . 
     To obtain data for the envelope of the sulcus section of abutment  14  designated by  24  in  FIG. 1 , the first measured points  48 ,  50  are connected with the second measured points  52 ,  54 , with the contour of the connecting lines determined from the scanned data of so-called sulcus area  38  in working model  26 , which is preset by the contour of the gum that runs between emergence line  46  and zero point line  64 . In this way, data for a sulcus section model are generated that are needed to produce sulcus section  24  in CAM technology. 
     According to the invention, a possibility exists to configure sulcus section  24  individually not just by altering sulcus line  46  in its progression, but rather the surface data of the sulcus section model determined from the measured data can also be altered to the degree that the surface is smoothed. With this, in supplemental fashion and in an emphasized configuration, provision is made that the surface is altered so that it runs with its full extent in convex fashion in the axial direction, if necessary with straight-line sections, and is basically convex radially. However, this does not preclude obtaining locally concave surface areas when computing the sulcus section model that are not smoothed, so that sulcus section  24  produced using CAD-CAM technology has appropriate indentations. 
     Provision especially is made that the sulcus section model produced from the measured data while making allowance for the library data of the sulcus-former  62 , from which the sulcus section  24  is produced using CAD-CAM technology, is expanded in the area of emergence profile line  46 , so that as a consequence sulcus section  24  fully adjoins the gum in the area where the abutment emerges from the gum line. 
     In addition, in a preferred manner, the contour of emergence profile line  46  is altered to the extent that the emergence profile line needed to construct sulcus section  24  is shifted in the direction of the sulcus line. Thus, the emergence profile line taken into account for production of sulcus section  24  can run, for example, at an interval of up to 0.5 mm to the measured emergence profile line. 
     In  FIG. 1 , the emergence line allowed for in producing sulcus section  24  is designated by reference symbol  146  and the zero point line by the reference symbol  164 , which coincides with the surrounding band  20 . 
     The upper section or head section  70  of abutment  14  surrounded by the facing crown  16  can also be individually configured. For this provision is made that a physical wax up is inserted into gap  28 , that corresponds to the tooth to be replaced from the outer configuration. This is followed a scanning to determine the surface geometry. This surface geometry is reduced while allowing for the thickness of the facing crown  16 , to determine the surface geometry of head section  70  of abutment  14  on the basis of these data. Thus, the facial and/or buccal and/or mesial and/or distal and/or lingual and/or occlusal surface of head section  70  can geometrically follow the contour of the corresponding outer surfaces of facing  18 . 
     Abutment  14  itself is produced from a blank or a semi-finished product. An appropriate blank or semi-finished product can already have implant section  25  as a prefabricated section.