Abstract:
A method for producing a three-dimensional model of a region of a jaw for producing a dental restoration includes fully-automatic shaping of a recess for accommodating a laboratory analogue into the alveolar ridge of the model. Three-dimensional scanning data is used in the shaping and the depth, position, and orientation of the recess are shaped such that the crestal end of the laboratory analogue inserted into the recess coincides with the crestal end of the dental implant in the jaw of a patient. The method may also include fully-automatic shaping of a vestibular, lingual or palatinal feed-through through the model into the recess, wherein the three-dimensional scanning data are used in the shaping and the feed-through is arranged such that the crestal end of a laboratory analogue coincides with the crestal end of the dental implant in the jaw of the patient, when the laboratory analogue is fixed in place.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to methods for producing a laboratory analogue using three-dimensional scanning data of the oral space of the patient, whereby the data was recorded previously. 
         [0002]    The invention also relates to methods for producing a three-dimensional model of at least a partial region of a jaw of a patient for at least one laboratory analogue having at least one recess for accommodating at least one laboratory analogue using three-dimensional scanning data of the oral space of the patient, whereby the data was recorded previously. 
         [0003]    And lastly, the invention also relates to a laboratory analogue and a model produced using the method. 
         [0004]    Dental implants are used in dental medicine to replace teeth that have fallen out or were extracted. Dental implants are inserted into the jaw bone for this purpose. Dental implants to be inserted into the jaw bone are known from DE 10 2007 029 105 A1. The dental implant comprises a cylindrical bore hole having an internal thread. Moreover, the dental implant is structured to have marks that are designed to ensure that the superstructure cannot be inserted into the dental implant at arbitrary angles. 
         [0005]    Laboratory analogues are needed to allow a dental technician to carve a restoration on an implant superstructure in the laboratory for later insertion in the patient. For this purpose, laboratory analogues have a material-specific geometry and shape. In most cases, an impression is taken with an impression compound for this purpose and subsequently used to fabricate a plaster model of the jaw of the patient by casting plaster into the impression. The laboratory analogue becomes integrated into the model of the jaw in the appropriate position during this process. The geometry and shape of the laboratory analogue need to be matched to the plaster for this purpose. The model of the jaw with the integrated laboratory analogue is then used by the dental technician to shape the implant superstructure and the dental restoration to match the situation existing in the oral space of the patient. 
         [0006]    Another method for providing a model of the jaw and the incorporation scenario has been in use for some time instead of the above-described method. It involves the use of, e.g., an intraoral scanner to first record the three-dimensional situation in the oral space of the patient and storing this digital information in electronic memory of a computer. Most often, CAD programs are used for this purpose. Subsequently, a model of the jaw is generated in known manner using a light-curing plastic material and a laser. The laboratory analogues are then inserted into the plastic models of the jaw. In turn, the plastic model of the jaw harboring the laboratory analogue can then be used by the dental technician to build up the dental restoration. 
         [0007]    A disadvantage of this procedure is that the incorporation situation is not exactly defined for the dental technician on the jaw model. In particular, where superstructures need to be fixed to multiple dental implants in the jaw of the patient, undesired tension may be produced in the jaw bone if the position and the orientation of the laboratory analogues in the model do not match the situation in the oral space to a sufficiently accurate degree. This can cause the patient pain and can put stress on the jaw bone which may lead to implant loss in the worst case. For this reason, it is crucial as early as during the production of the model and the positioning and orientation of the laboratory analogues with respect to each other to carry out all steps at the highest accuracy possible. 
         [0008]    If the dental restoration inserted by the dentist does not exactly match the situation in the oral space of the patient, the dentist may need to adapt the dental restoration on site or, in the worst case, have the entire dental restoration re-fabricated. Moreover, the laboratory analogue is not all that easy to affix in the proper position such that there may some changes of position during the production of the dental restoration resulting in incorrect fitting of the dental restoration. This is the case, because the laboratory analogue is arranged on the model such that it can rotate and shift in its longitudinal direction. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    Accordingly, it is the object of the invention to overcome the disadvantages of the prior art. Specifically, a way is to be devised that allows a model of the jaw or a laboratory analogue, in particular a plastic model of the jaw fabricated through rapid prototyping, with laboratory analogues inserted for producing a dental restoration to be produced at the highest possible accuracy such that there is less scrap during the production of the dental restoration and such that the dentist inserting the dental restoration has to carry out fewer or no additional adaptations. Moreover, modern methods should be usable in the production of the model of the jaw. 
         [0010]    The method-related object of the invention is met through a method for producing a laboratory analogue for dental implants comprising the steps of: 
         [0011]    providing at least one sleeve comprising a cylindrical depression having an internal thread; 
         [0012]    providing a three-dimensional model of at least a partial region of the jaw of a patient who harbors at least one dental implant; 
         [0013]    inserting at least one sleeve into at least one recess of the model matching the sleeve, whereby each recess is arranged in a region of the model, in which a dental implant is arranged in the jaw of the patient; and 
         [0014]    fully-automatic ablation of at least one inserted sleeve, whereby the ablation is controlled through three-dimensional scanning data of the oral space of the patient, whereby the data was recorded previously, and the sleeve is ablated based on such data to the extent that the crestal end of the laboratory analogue produced from the sleeve coincides with the crestal end of the dental implant in the jaw of the patient. 
         [0015]    In this context, the invention can provide the sleeve to be ablated, in particular cut, ground and/or milled off, proceeding from the crestal direction. 
         [0016]    The method-related object of the invention is also met by a method for producing a three-dimensional model of at least a partial region of a jaw for producing a dental restoration, comprising the steps of: 
         [0017]    providing three-dimensional scanning data of an oral space of a patient, who harbors at least one dental implant, whereby the data was recorded previously; 
         [0018]    preparing a three-dimensional model of at least the partial region of the jaw; and 
         [0019]    fully-automatic shaping of at least one recess for accommodating a laboratory analogue into the alveolar ridge of the model, whereby the three-dimensional scanning data is used in the shaping and the depth, position, and orientation of the at least one recess are shaped such that the crestal end of the laboratory analogue inserted into the recess coincides with the crestal end of the dental implant in the jaw of the patient. 
         [0020]    In this context, the invention can provide the laboratory analogue, in particular a standard laboratory analogue, to be inserted into the recess or a sleeve to be inserted into the recess, whereby a laboratory analogue is produced from the sleeve through ablation, whereby it is preferable to use the three-dimensional scanning data in order to ablate the sleeve fully-automatically. 
         [0021]    This method allows the advantages of a method according to the invention for producing the laboratory analogue and having the recess in the model to be combined. 
         [0022]    Moreover, the method-related object of the invention is met by a method for producing a three-dimensional model of at least a partial region of a jaw for producing a dental restoration, comprising the steps of: 
         [0023]    providing three-dimensional scanning data of an oral space of a patient, who harbors at least one dental implant, whereby the data was recorded previously; 
         [0024]    preparing a three-dimensional model of at least a partial region of the jaw with at least one recess for accommodating a laboratory analogue having an opening, whereby each recess is arranged in a region of the model, in which a dental implant is arranged in the jaw of the patient; and 
         [0025]    fully-automatic shaping of at least one vestibular, lingual or palatinal feed-through through the model into the at least one recess, whereby the three-dimensional scanning data are used in the shaping and the feed-through is arranged such that the crestal end of a laboratory analogue coincides with the crestal end of the dental implant in the jaw of the patient when the laboratory analogue is fixed in place with a pin that is inserted through the feed-through in the model into an opening in the laboratory analogue. 
         [0026]    In this context, the invention can provide the feed-through to be shaped to match the pin and the opening to match the pin, preferably in that a depression in the laboratory analogue arranged downstream of the opening matches the pin. 
         [0027]    Moreover, methods according to the invention for producing models can provide the fully-automatic shaping to proceed by means of drilling, turning, grinding, cutting out and/or milling. 
         [0028]    The production methods can be implemented in particularly precise and efficient manner through the use of fully-automatic computer-supported methods. 
         [0029]    The invention can also provide the fully-automatic shaping and/or ablation, which is preferably carried out in computer-supported manner, to be carried out at an accuracy of at least ±10 μm, preferably at an accuracy of at least ±5 μm. 
         [0030]    Such accuracy is sufficient to allow the abutments, abutment superstructures, and other superstructures to be attached to the dental implants without any tension arising. Moreover, at the specified accuracies, the scan of the oral space can be carried out with known methods without any major effort. 
         [0031]    Moreover, the invention can provide the three-dimensional scanning data of the oral space of the patient to be used in the production, in particular fully-automatic production, of the three-dimensional model of the jaw or region of the jaw, whereby the model is preferably produced by means of rapid prototyping (rapid model construction), particularly preferably at an accuracy of at least ±100 μm, yet more preferably at an accuracy of at least ±60 μm. 
         [0032]    Combining the easy and inexpensive production of the model with the refinement attained through fully-automatic ablation of the sleeve or shaping of the recess or feed-through results in a method that is rapid and as inexpensive as possibly and concurrently offers high accuracy and a precise starting position for the dental technician. 
         [0033]    Another refinement of the invention can provide for the use of a CAD-based stereolithographic method to obtain the data for production of the model and/or laboratory analogue, and for the model to preferably be fabricated from plastic material, particularly preferably from a light-curing plastic material. 
         [0034]    In this context, the previously recorded scanning data of the oral space of the patient can be used again and it is feasible to almost fully automate the production of the model with the laboratory analogue or laboratory analogues. 
         [0035]    Particularly preferably, the invention provides for the use of a five-axis processing, in particular a five-axis CNC milling machine, in the shaping and/or ablation, in particular for milling and/or grinding. 
         [0036]    The five-axis processing enables better accuracy during the processing than rapid prototyping and thus leads to improved models. 
         [0037]    Moreover, the invention can provide at least two recesses to be generated or to exist in the three-dimensional model and preferably one sleeve each or one laboratory analogue each to be inserted into each of the recesses, whereby the position of the recess or feed-throughs and/or crestal ends of the laboratory analogues with respect to each other are adjusted by means of shaping and/or ablating based on the scanning data. 
         [0038]    The advantages of the invention are implemented in particular if multiple laboratory analogues are used to build up a superstructure to be attached to multiple dental implants, since the method allows especially the position and orientation of the laboratory analogues with respect to each other to be adjusted very accurately. 
         [0039]    Moreover, the invention can provide at least one cylindrical or conical recess to be generated or to exist in the model, whereby the recess is generated or exists to have one-fold or n-fold rotational symmetry about the longitudinal axis of the recess, and a sleeve or a laboratory analogue with the same rotational symmetry, at least over regions thereof, to be inserted into the recess such that it fits in the recess only in one orientation or in the n-fold orientation. 
         [0040]    This serves to always attach the superstructures and/or abutments in the correct position in the model and, later, on the dental implants in the oral space. 
         [0041]    In this context, the invention can provide that at least one sleeve or one laboratory analogue is used which preferably fits in the recess in a perfect fit. 
         [0042]    Methods according to the invention can also be characterized in that the at least one recess is predefined during the production of the model to have a fixed defined shape that fits a certain shape of a sleeve or laboratory analogue, and/or a shape of the recess to be selected from a multiplicity of different shapes that match a multiplicity of different sleeves or laboratory analogues, whereby the shape is integrated into a measured virtual digitized jaw model as a recess preferably before the model is produced. 
         [0043]    The invention can just as well provide at least one sleeve or at least one laboratory analogue to snap-in into counter-snap-in locking means by means of snap-in locking means or is connected through a bayonet closure in an angled depression of at least one recess. 
         [0044]    The longitudinal axis of the recess is the axis along which the laboratory analogue can be introduced into or removed from the recess. It usually coincides with the central axis of the recess. A crestal direction shall be understood to mean a direction from the alveolar ridge of premolar teeth in occlusal direction, i.e. toward the mastication surface. Direction information such as vestibular (towards the oral vestibule), lingual (on the tongue side of the mouth in case of the lower jaw), and palatinal (on the cheek side in the mouth in case of the upper jaw) also refers to the jaw. 
         [0045]    Referring to one-fold rotational symmetry axes, reference is made to the one-fold rotational symmetry axis that coincides with the rotational symmetry axis of the cylindrical or conical basic shape of the sleeve and/or laboratory analogue. In most cases, a cylindrical or conical shape is selected as the basic shape of the laboratory analogue and thus of the recess, whereby grooves, depressions or projections break the symmetry of the basic shape. Accordingly, the rotational symmetry axis of the basic shape is to be seen as the symmetry axis. 
         [0046]    Moreover, the invention can provide for a CAD-based stereolithographic method to be used for producing the model and the model to preferably be fabricated from plastic material, particularly preferably from a light-curing plastic material. 
         [0047]    The methods are particularly well-suited for implementing methods according to the invention since the recesses can thus be integrated very easily and without major computation into the jaw models even with simple, easily obtainable computers. 
         [0048]    The invention can just as well provide for the dental restoration to be screwed directly to the laboratory analogue as the final step of the method. Alternatively, an abutment superstructure and/or implant superstructure can be mounted on the laboratory analogue and finalized. 
         [0049]    Preferably, methods according to the invention can just as well provide for a computer to be used during the production of the recess or feed-through, in particular a digitization of the oral space of the patient, whereby the shape of the recess is read-out from a memory unit of the computer and whereby different fitting shapes of recesses are assigned, in particular, to different laboratory analogues, whereby these are preferably selected by the computer and/or a user using an input unit. 
         [0050]    Using a computer for production of the model results in a special combination effect in that all data for production of the model are already stored on the computer, which means that the surface of the model is stored therein. In this case, the surface of the model only needs to be modified appropriately such that the recess becomes arranged at the proper site thereof to match the laboratory analogue that is best suited or which has previously been selected by the computer or is the only one stored therein. The model can then be produced to have the modified surface right away, meaning jointly with the matching recess. 
         [0051]    The invention can just as well provide for the use of a laboratory analogue that has the same rotational symmetry along its longitudinal axis, at least over regions thereof, as the recess and which preferably fits in the recess in a perfect fit or whose thread perfectly fits the counter-thread of the recess. 
         [0052]    Using a laboratory analogue of this type ensures that the recess matches the region of the laboratory analogue and therefore ensures that the laboratory analogue is attached well in the model. 
         [0053]    The invention can provide the recess to be predefined during the production of the model to have a fixed defined shape that matches a certain laboratory analogue, and/or a shape of the recess to be selected from a multiplicity of different shapes that match a multiplicity of different laboratory analogues, whereby the shape is being integrated as a recess into a measured virtual digitized model of the jaw, preferably before the model is produced. 
         [0054]    This allows a particularly user-friendly and/or variable method to be designed. The strength of the invention can be implemented in beneficial manner especially through these options. 
         [0055]    The use of computers for implementing methods according to the invention is particularly suitable, since especially the more recent methods are already in use in computer-supported manner for producing the models, such that there is only a need to include a simple software supplement and the data related to the surfaces of the recesses and/or laboratory analogues in order to improve the dental restoration thus produced. 
         [0056]    In this context, the invention can provide multiple shapes of different recesses to be stored in the storage unit and one recess to be selectable through an input facility and/or to be defined by the computer based on model preparation data, whereby the recess, in particular, can be selected from a computer-determined pre-selection of recesses that match the laboratory analogues. 
         [0057]    The object of the invention is also met by a laboratory analogue produced according to a method according to the invention for producing a laboratory analogue, in which the crestal end of the laboratory analogue corresponds to the data of the three-dimensional scan of the oral space of the patient at an accuracy of at least ±10 μm, preferably at an accuracy of at least ±5 μm, when it is inserted in a corresponding model of the jaw. 
         [0058]    The object of the invention is also met by a model of at least a partial region of a jaw, produced according to a method of this type for producing a model, comprising at least one recess, in which the accuracy of the dimensions of the at least one recess and preferably the orientation and position of all recesses with respect to each other is at least ±10 μm, preferably the accuracy is at least ±5 μm, relative to the three-dimensional scanning data of the oral space of the patient such that the orientation and position of the crestal ends of the laboratory analogues inserted in the model corresponds to the orientation and position of all crestal ends of the dental implants at the accuracy. 
         [0059]    And finally, the object of the invention is also met by a model of at least a partial region of a jaw, produced according to a method of this type for producing a model, comprising at least one feed-through and at least one recess, in which the accuracy of the position of the at least one feed-through and preferably the orientation and the position of all feed-throughs with respect to each other is at least ±10 μm, preferably the accuracy is at least ±5 μm, relative to the three-dimensional scanning data of the oral space of the patient such that the orientation and position of the crestal ends of the laboratory analogues affixed in the model by means of the pins extending through the feed-throughs corresponds to the orientation and position of all crestal ends of the dental implants at the accuracy. 
         [0060]    A model of this type provides a basis for the use of a rotationally-fixed and even position-fixed superstructure for producing high quality dental restorations. 
         [0061]    In this context, the invention can provide counter-snap-in means in the recess that engage snap-in means on the laboratory analogue and keep the laboratory analogue in a fixed position. 
         [0062]    This again serves to affix a laboratory analogue inserted into the recess of the model both better and more accurately. 
         [0063]    The possibility of using different laboratory analogues and the selection of a particularly well-suited laboratory analogues allow for further improvements to be made to the final result thus produced. 
         [0064]    The invention is based on the surprising finding that the quality and especially the accuracy of the dental restoration produced with modern methods such as “rapid prototyping” and/or stereolithographic methods for producing jaw models can be improved through reproducing the accuracy of the scan in the model or laboratory analogue or laboratory analogues by utilizing the scan data in the automatic shaping or ablating during the production of the model and/or during the production of the laboratory analogue or laboratory analogues. This can be effected according to the invention, preferably through the use of five-axis procedures such as five-axis polishers, mills, cutters and/or drills that are controlled based on the scan data of the oral space of the patient. In this context, various other measures according to the invention can allow the laboratory analogues to be arranged particularly positionally-precise, non-rotatably or even in fixed position. 
         [0065]    The methods according to the invention allow not only the position of an individual crestal end of a single laboratory analogue to be defined accurately, but also, and mainly, the position and orientation with respect to each other of different crestal ends of multiple laboratory analogues to be adjusted accurately. This results in advantages during the production of superstructures that are to be attached to multiple dental implants. 
         [0066]    Moreover, the recess can be produced to have the properly fitting shape right when it is produced in the jaw model if the surface required for the recess is integrated into a virtual model right away and each recess is generated right away accordingly during the production. Moreover, it is also feasible to right away select a particularly well-fitting recess with a matching laboratory analogue if multiple different laboratory analogues and the matching recesses are stored and thus are available for selecting. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0067]    The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. 
           [0068]    In the drawings: 
           [0069]      FIG. 1  shows a schematic perspective view of a laboratory analogue having a projection for forming a bayonet closure for implementing a method according to an embodiment of the invention; 
           [0070]      FIG. 2  shows a schematic perspective and transparent partial view of a jaw model for accommodating the laboratory analogue according to  FIG. 1  for implementing a method according to an embodiment of the invention; 
           [0071]      FIG. 3  shows a schematic perspective view of a sleeve with broken rotational symmetry for implementing a method according to an embodiment of the invention; 
           [0072]      FIG. 4  shows a schematic perspective and transparent partial view of a jaw model for accommodating a sleeve according to  FIG. 3  for implementing a method according to an embodiment of the invention; 
           [0073]      FIG. 5  shows a schematic perspective view of an alternative laboratory analogue for implementing a method according to an embodiment of the invention; 
           [0074]      FIG. 6  shows a schematic perspective, transparent partial view of a jaw model having a feed-through for fixation of a laboratory analogue according to  FIG. 5  for implementing a method according to an embodiment of the invention; 
           [0075]      FIG. 7  shows a schematic perspective view of another laboratory analogue for implementing a method according to an embodiment of the invention; and 
           [0076]      FIG. 8  shows a detail of a schematic cross-sectional view of a jaw model for implementing a method according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0077]      FIG. 1  shows a laboratory analogue  1  that is well-suited for implementing a method according to the invention. The laboratory analogue  1  has a cylindrical base  2  that is fabricated from metal. The laboratory analogue  1  can be fabricated, for example, from metal. A hexagonal superstructure  3  is arranged on the top of the laboratory analogue  1 . 
         [0078]    If a laboratory analogue  1  or a sleeve with a hexagonal superstructure  3  is used, the abutment has on its base-side a  6 -fold rotational symmetry, i.e. that the region and the surface of the abutment can be made to geometrically coincide with itself through six different rotations of less than  360 ° about its longitudinal axis. The term, abutment, can also be understood to mean an implant superstructure with connection geometry. A rectangular or elliptical superstructure would lead to  2 -fold symmetry and can be used just as well. The abutment can therefore be placed on the laboratory analogue  1  at defined angles only. 
         [0079]    A cylindrical hole  4  having an internal thread  4  is arranged in the center of the laboratory analogue  1 . The hole  4  extends deep into the inside of the base  2  and along the symmetry axis of the cylindrical base  2 . But the hole  4  preferably does not extend all the way to the opposite side of the laboratory analogue  1 . 
         [0080]    A projection  5  is attached on the jacket surface of the cylindrical base  2  and can take the shape of a semi-sphere. The projection  5  is to form a bayonet closure in concert with a corresponding recess in a jaw model of a patient. 
         [0081]    A part of a model  6  of this type is shown in a transparent schematic view in  FIG. 2 . The model  6  continues on the right and left as is indicated through the non-finalized straight lines in  FIG. 2 . In reality, the model  6  is preferably not to have the type of edges shown through the straight lines, but shows an alveolar ridge with or without teeth depending on the actual situation in the oral space of the patient. 
         [0082]    A recess  7  is situated in the model  6  and extends into the model  6  as a cylindrical hole. The diameter of the recess  7  is slightly larger than the diameter of the laboratory analogue  1  according to  FIG. 1 , such that the laboratory analogue  1  can be inserted into the recess. An angled groove  8  is provided in the cylinder wall of the recess  7  and forms a bayonet closure in concert with the projection  5  according to  FIG. 1 . The laboratory analogue  1  can be attached in the model  6  through inserting the laboratory analogue  1  into the recess  7 , whereby the projection  5  is guided in the groove  7 . The laboratory analogue  1  preferably cannot be inserted further at the angling of groove  7 , but is rotated clockwise until it reaches the limit stop of groove  7  and projection  5  blocks any further rotation. 
         [0083]    The laboratory analogue  1  is fabricated from a sleeve (not shown) that is slightly longer than the laboratory analogue  1  shown, but already has the same diameter as the base  2  and has a hexagonal superstructure  3  and the projection  5 . The sleeve is preferably firmly connected to the model  6  by means of the bayonet closure  5 ,  8 . 
         [0084]    The sleeve is then milled off by means of a five-axis milling machine, whereby the five-axis milling machine is controlled automatically based on previously recorded three-dimensional scanning data of the oral space of the patient. In this context, the orientation and position of the crestal end of the sleeve are milled off at high accuracy such that the end corresponds very closely to the orientation and position of the crestal end of the dental implant in the jaw of the patient once it is milled off. Especially the position and orientation of multiple dental implants with respect to each other is reproduced very accurately in the model  6  in this process. The laboratory analogues  1  in the model  6  thus produced from the sleeves are then very well-suited for producing the superstructure, in particular a superstructure anchored on multiple dental implants. 
         [0085]    In contrast, the model  6  can initially be produced through simple rapid prototyping since the inaccuracies in the production of the model are evened out later on through after-working with the five-axis milling machine. 
         [0086]      FIG. 3  shows a schematic perspective view of a sleeve  11  for an alternative laboratory analogue that has a base  2  with a flat portion  15 . The purpose of the flat portion  15  is to ensure that the sleeve  11  and the laboratory analogue fabricated from the sleeve  11  can be inserted into the matching model  16  according to  FIG. 4  in one position only. The sleeve  11  also has a hexagonal superstructure  3  for orientation of an abutment and a hole  4  with an internal thread for attachment of the abutment. Accordingly, the sleeve  11  resembles the laboratory analogue  1  according to  FIG. 1 . Basically, it is conceivable, although unlikely, that the unprocessed shape of the sleeve  11  would perfectly match the situation inside the oral space. In this case, the sleeve  11  could be used directly as a laboratory analogue. This means that there is no fundamental difference between the sleeve  11  and the finished laboratory analogue. However, the sleeve  11  should usually be longer since it generally cannot be made longer artificially and needs to be milled off or ablated in any other manner to be able to produce laboratory analogues of any length from the sleeve  11 . 
         [0087]    The model  16  has a recess  7  which also comprises a flat portion  18 , such that the shape of the recess  7  matches the shape of the base  2  of the sleeve  11 . Once the sleeve  11  is inserted, a five-axis processing, preferably using a five-axis CNC milling machine, is used to fully automatically mill off the inserted sleeve  11  at its crestal end (on the top in  FIG. 3 ). The five-axis CNC milling machine receives the data for this process from an electronic memory, in which the data of a scan of the oral space of the patient are stored. The situation in the oral space and, in particular, the position and orientation of all dental implants in the jaw of the patient to be treated are recorded at high accuracy during the scan (inaccuracy of less than 10 μm). 
         [0088]    Whereas the model  16  was produced through rapid prototyping from the same data but at lower accuracy, ablation of the sleeves  11  through the more accurate five-axis processing allows laboratory analogues to be produced whose position and orientation correspond to the situation, in particular the position and orientation of the dental implants, in the oral space of the patient, preferably at an accuracy of at least 10 μm. Especially where a superstructure is to be attached to multiple dental implants, the high accuracy of the present method is advantageous in order to prevent any tension exerted on the jaw by superstructures that have not been fabricated at sufficient accuracy in concert with the dental implants. 
         [0089]      FIG. 5  shows a schematic perspective view of an alternative laboratory analogue  21  for implementing a method according to the invention. The laboratory analogue  21  has a cylindrical base  2  whose upper crestal end has a depression  23  provided on it. The depression  23  serves to accommodate an abutment for producing a superstructure to be inserted, for example, as a dental restoration or as a superstructure in the oral space of a patient on a dental implant having the same crestal end. A hole having an internal thread (not shown) for attachment of the abutment is situated in the depression  23 . An accommodation opening  25  is provided in the cylinder jacket of the laboratory analogue  21  and opens into a cylindrical depression in the base  2  of the laboratory analogue  21 . 
         [0090]    The laboratory analogue  21  is a standard part, in which the position and orientation of the accommodation opening  25  and of the cylindrical depression in the jacket of the base  2  were fabricated at high accuracy, for example an accuracy of at least 6 μm. 
         [0091]      FIG. 6  shows a schematic perspective and transparent partial view of a jaw model  26  having a feed-through  28  for fixation of a laboratory analogue  21  according to  FIG. 5  in a recess  7  of the model  26  for implementing a method according to the invention. The feed-through  28  has the same geometry as the cylindrical depression in the jacket of the base  2  of the laboratory analogue  21 . The laboratory analogue  21  is to be inserted from above into the recess  7  such that the cylindrical depression in the jacket of the base  2  extends the feed-through  28 . Subsequently, the laboratory analogue  21  can be affixed with a pin (not shown) that matches the geometry of the feed-through  28  and of the cylindrical depression in the jacket of the base  2  through inserting the pin through the feed-through  28  into the cylindrical depression in the cylinder jacket of the base  2 . 
         [0092]    A marking can be provided on the laboratory analogue  21  to indicate the position of the opening  25  in order to make it easier for the dental technician to insert the laboratory analogue  21 . 
         [0093]    The model  26  is preferably initially fabricated without the feed-through  28  by means of rapid prototyping. This renders the accuracy of the model  26  to be approximately 60 μm. In this context, the accuracy of the data used for fabrication of the model  26  by rapid prototyping is higher, for example up to 3 μm. The model  26  without feed-through  28  is then clamped and fixed in place in a bracket of a drilling machine or other facility for generating a feed-through  28  at high accuracy that allows for drilling at high accuracy, for example an accuracy at the level of the accuracy of the position of the cylindrical depression in the jacket of the base  2  in the laboratory analogue  21  (6 μm). A computer uses the data to calculate the position of the bore hole in order to position the laboratory analogue  21  upon fixation with the pin such that the position of the crestal end of the laboratory analogue  21  coincides with the position of the crestal end of the dental implant in the jaw of the patient. And lastly, the feed-through  28  in the model  26  is generated. 
         [0094]    Likewise, any other feed-throughs in the model  26  (not shown), if applicable, are generated and the position and orientation of the crestal ends of the laboratory analogues  21  with respect to each other is thus adjusted appropriately such that these coincide with the position and orientation of the crestal ends of all dental implants in the jaw of the patient. 
         [0095]      FIG. 7  shows a schematic perspective view of another laboratory analogue  31  for implementing a method according to the invention. The laboratory analogue  31  is a cylindrical body having a groove  35 . A hole  4  having an internal thread is provided along the cylinder axis of the laboratory analogue  31 . An abutment can be screwed into the internal thread. The crestal end in FIG. 
         [0096]      7  is situated on the bottom, unlike in  FIGS. 1 ,  3 , and  5 . 
         [0097]      FIG. 8  shows a schematic cross-sectional view of a detail of a jaw model  36  according to the invention. A recess  7  for accommodation of a laboratory analogue  31  is arranged in the model  36 . As a matching counterpart to the laboratory analogue  31  according to  FIG. 7 , the model  36  comprises a projection  38  that fits in the groove  35  of the laboratory analogue  31  and thus unambiguously defines the position of the laboratory analogue  31 . 
         [0098]    The model  36  comprises gingiva  45 , alveolar ridge  46 , and teeth  47 , or parts thereof to be exact. The model  36  is fabricated from plastic material and has been generated based on data obtained using a stereolithographic method by performing a scan of an oral space of a patient. The opposite part of the jaw (not shown) can also be part of the model  36  in order to be able to represent the situation upon mastication, for example with the mouth closed. Accordingly, the model  36  can continue not only on the right and left, as indicated through the dashed lines. 
         [0099]    The model  36  comprises the recess  7  in the form of a cylindrical hole in a site between the teeth  47 . The cylindrical rotational symmetry of the recess  7  is broken through the projection  38 . This secures the exact position of a laboratory analogue  31 , such as the one according to  FIG. 7 , in the model  36 , against both rotation and positional change. 
         [0100]    For a laboratory analogue  21  and/or a sleeve  11  as shown in  FIG. 3  or  5 , the recess  7  in a matching model would be built as a cylindrical hole with a flat portion or a feed-through through the gingiva  45  at the alveolar ridge  46 , which would keep the laboratory analogue  21  and/or sleeve  11  in position safe against rotation. The advantage of the structure is that the laboratory analogue  31  can be taken out quickly, whereas the laboratory analogue  21  according to  FIG. 5  can be fixed in place better and more accurately. 
         [0101]    Another particularly preferred exemplary embodiment of a method according to the invention is illustrated in the following. Measurements of the oral space are made for production of a well-fitting dental restoration. For this purpose, a three-dimensional image of the oral space, and/or, in particular, the respective part of the jaw, is recorded. These data are then stored in a memory of a computer. During the recording, the positions of all dental implants in the jaw of the patient are defined accurately by inserting standard positional markers in the dental implants for the scan, whereby the markers can be identified unambiguously during the scan and render the position and orientation of the dental implants exactly defined by the scan. 
         [0102]    These data are used to calculate a virtual three-dimensional CAD model of the jaw or of part of the jaw in a computing unit of the computer. Different recesses  7  or basic recess shapes are stored in the memory of the computer and are assigned to different laboratory analogues  1 ,  21 ,  31  and/or sleeves  11 . The computer calculates how the various recesses  7  might be arranged in the model  6 ,  16 ,  26 ,  36 . The most stable or most reasonable variant is selected or the most stable or most reasonable variants are proposed by means of a display facility. A criterion in this context can be, for example, how thick is the wall of the model  6 ,  16 ,  26 ,  36  in the region of the recess  7  in the alveolar ridge  46  for the various recesses  6 ,  16 ,  26 ,  36  or which is the most well-suited laboratory analogue  1 ,  21 ,  31  and/or sleeve  11  for the position in the jaw. 
         [0103]    Alternatively, the user can select from all stored recesses  7  the one deemed most suitable. The invention can just as well provide the computer to indicate, based on a calculation, that a selected recess  7  is not feasible or not reasonable, for example is not stable enough, if applicable. Moreover, it is feasible that only one recess  7  is stored for a particular type of laboratory analogues  1 ,  21 ,  31  and/or sleeves  11 . 
         [0104]    Subsequently, the recess  7  selected by means of an input facility or the pre-determined recess  7  is combined with the virtual model of the jaw. For this purpose, the recess  7  is included in the calculation of the virtual model as a surface of the virtual model at the respective site at which the dental implant is arranged in the jaw of the patient. The new virtual model is then used to generate an actual model  6 ,  16 ,  26 ,  36  using known methods, such as, for example, rapid prototyping methods. For this purpose, the computer is connected to a manufacturing facility designed for implementing methods of this type. 
         [0105]    Just as well, the recess  7  may not yet be included in the model  6 ,  16 ,  26 ,  36  or may be designed as a precursor, that is too small in size. The final shaping of the recess  7  is effected using a more accurate manufacturing method than rapid prototyping. Conceivable in this regard are five-axis processing methods that utilize the higher accuracy of the scanning data to generate the recess  7  and its position and orientation to each other at higher accuracy. Accordingly, recess  7  is subjected to precision processing such that the position, orientation, and depth of the recess  7  in the model and, if applicable, of the recesses with respect to each other are fabricated appropriately such that the crestal ends of the inserted laboratory analogues  1 ,  21 ,  31  coincide exactly with the orientations and positions of the crestal ends of the dental implants in the jaw and, if applicable, of the dental implants with respect to each other. 
         [0106]    Accordingly, either the recess  7  can then be processed with a precision tool, for example through a five-axis processing, based on the more accurate scanning data or, alternatively, a feed-through can be drilled accurately in order to define the position and orientation of a prefabricated laboratory analogue  1 ,  21 ,  31  at high accuracy. Another alternative allows a sleeve  11  inserted in the recess  7  to be ablated, additionally or alternatively, with a precision tool, for example through a five-axis processing, based on the more accurate scanning data, in order to produce the exactly correct length and arrangement of the laboratory analogue  1 ,  21 ,  31  thus generated. 
         [0107]    The actual dental restoration can then be generated on the superstructure  3  of the laboratory analogue  1 ,  21 ,  31  in a realistic environment and in accurate position. Whenever the laboratory analogue  1 ,  21 ,  31  or the sleeve  11  is removed from or re-inserted into the model  6 ,  16 ,  26 ,  36 , it will be situated in the same position in the jaw model  6 ,  16 ,  26 ,  36 . This ensures that the dental restoration has the exactly correct shape. Moreover, the dental restoration will also be arranged in the same position in the oral space of the patient on the actual dental implant such that a particularly good fit is guaranteed. 
         [0108]    The features of the invention disclosed in the preceding description and in the claims, figures, and exemplary embodiments, can be essential for the implementation of the various embodiments of the invention both alone and in any combination. 
         [0109]    It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.