The invention relates to a method for producing an individually made, implant-supported tooth replacement, in particular from any arbitrary, also biocompatible, materials, and more particularly with the aid of CAD-CAM technology. The invention further relates to a method for producing a tooth replacement element, which is intended to be positioned and fastened on at least one implant, or at least one tooth stub.
Within the scope of the present invention, the term xe2x80x9ctooth replacementxe2x80x9d is understood to be a structure which complements or replaces not only the visible portion of a tooth or a group of teeth, but also its root, and which therefore constitutes a complete replacement of one or several teeth of a patient. In the finished state, this tooth replacement consists of several components, which are interlocked or fastened on each other. Thus, within the scope of the present invention, the term xe2x80x9ctooth replacement elementxe2x80x9d is understood to be a structure which is supported on an implant or a tooth stub, and which essentially projects past the jawbone and the gums. A tooth replacement element can in particular constitute a component of an implant-supported tooth replacement.
The first component of the tooth replacement is an implant, which is inserted into the jawbone of the patient and is then also called an implant insertion. The further components of the tooth replacement will be later built on this implant insertion. The implant insertion generally constitutes the basis for a tooth replacement replacing one or several teeth. A tooth replacement intended to replace one tooth is supported on a single implant, and a tooth replacement intended to replace several adjoining teeth is generally supported on at least two implants. The implants are intended to be implanted, or respectively inserted, by the dentist into the jawbone of a patient, and they are provided by the dentist ready to use and sterilized. The implants can be essentially designed to be cylindrical or tapering and are in the form of screws or pins. On its crown end, each implant has a positioning element. In the installed state of the tooth replacement, the implants are not visible on the patient, or only to a limited degree.
The second component of the tooth replacement is constituted by a connecting element, which in technical terms is called an abutment. One abutment is fastened on each implant. In the installed state of the tooth replacement the abutments are not visible in the patient, or only to a limited degree. They are used to connect the implants with the further components of the tooth replacement. Each abutment has a second positioning element on its proximal end which, together with the first positioning element arranged on the associated implant, forms a positioning device providing protection against rotation.
The third component of the tooth replacement is constituted by connecting elements, generally screws, for the mutual fastening of the implant and the abutment. These connecting elements are also not visible in the patient in the installed state of the tooth replacement. The mutual connection of the implant to the abutment is generally reversible.
The fourth component of the tooth replacement is called a framework, bridge frame or cap. It is secured against vertical displacement, or respectively fastened, on one or several abutments, generally with the aid of a suitable cement or adhesive, or by means of a horizontal or vertical screw connection. The individual cap can be used for replacing one tooth and can be mounted on one abutment. However, a structure made of several caps in connection with an intermediate member, called a portic, can also be intended as the bearing element for an implant bridge for replacing several teeth, and can be mounted on several abutments. Although caps are not, or only slightly, visible after the tooth replacement has been installed in the patient, their nature can have a certain influence on the esthetic aspect of the tooth replacement, which will be explained further down below.
The fifth component of the tooth replacement is constituted by a facing, which encloses the framework, or respectively the bridge frame, or respectively the cap. The facing is the only component of the tooth replacement which is visible in the installed state of the tooth replacement of the patient. The facing is intended to replace the visible area of the tooth. The framework, or respectively the bridge frame, or respectively the cap, on the one hand, and the facing on the other, are irreversibly connected with each other.
It is also possible to use a so-called full crown in place of the framework, or respectively the bridge frame, or respectively the cap, as well as the facing which, as just described, constitute the fourth and fifth component of the tooth replacement. In this case the tooth replacement comprises only four components, namely the implant, the abutment, the connecting elements and the full crown.
The framework and the facing together, or the full crown by itself, form a unit which will also be called a supra-structure within the scope of the present description. The supra-structure is fastened reversibly or irreversibly on the abutment. Reversibly fastened supra-structures can be removed from the abutment, if required.
In regard to functionality, shape and appearance, the tooth replacement should be as similar as possible to the natural tooth, or respectively the natural teeth, to be replaced, of the patient.
As already mentioned, within the scope of the present description the term tooth replacement should be understood to be a structure intended to be fastened directly or indirectly on implants or tooth stubs. On the one hand, the term tooth replacement includes abutments which are fastened on implants, frameworks which are fastened on abutments, and facings which are attached to the frameworks, furthermore also abutments which also constitute frameworks, and integral parts which include all components of a tooth replacement, with the exception of the implant itself. On the other hand, elements which can be fastened on prepared teeth, such as crown- or bridge-like elements, also fall under the term tooth replacement.
The production of implantable tooth replacements can take place in various ways, and the tooth replacement being made can also be embodied differently, as described above. In general, the planning and production of a tooth replacement comprises several method steps described in what follows, which are partially performed by a dentist and partially by a dental technician.
The area of responsibility of the dentist starts with the preparation of a negative impression, which is also called a jaw impression. The making of a negative impression, or respectively a jaw impression, is a method step wherein a measurement is taken of the patient, but which does not leave a trace on the patient, or respectively does not result in changes. Thereafter, a working model is made by the dental technician on the basis of the jaw impression. The working model represents the conditions in the jaw of the patient in which the tooth replacement is to be integrated. The dentist provides information regarding the number of implants, as well as other information, as required. Furthermore, the dentist inserts the implants. Another negative impression is taken after the insertion of the implants, which provides more accurate information to the dental technician, which will be described further down below. Following the prescribed required healing phase following the insertion of the implants in the jaw of the patient, the dentist lays the implants, or respectively their outer areas, open. The optimum position of the implants is of decisive importance for the shape of the further components in respect to occlusion, function and appearance. Unfortunately it is not always possible in the course of inserting the implants in the jaw of the patient to arrange them optimally in respect to the ideal expectation regarding occlusion, function and appearance. The result of this is that in respect to occlusion, function and appearance the tooth replacement can often not be optimally placed in the mouth of the patient. After some time, during which the implants grow in, the dentist finally attaches the remaining components of the tooth replacement on the implants.
As mentioned above, the dental technician begins with the production of a working model, which is made on the basis of the negative impression, or respectively the jaw impression provided by the dentist. The working model is always used in the further process. The essential work steps in producing the tooth replacement be performed on the working model.
Depending on the tooth replacement to be made, the dental technician inserts one or several manipulation implants, which are also called an analogous cast, in the working model. The manipulation implants are not a part of the tooth replacement to be made, they are merely aids for producing the tooth replacement. The analogous cast forms the basis for making the remaining components of the tooth replacement. The position of the analogous cast is determined by the jaw impression with the implants provided by the dentist. The precise representation of the positions of the implants is of decisive importance for the further production of the tooth replacement.
An abutment is attached to each model implant arranged on the working model. There are several possibilities for procuring suitable abutments. Premanufactured abutments can be used, which is a more cost-effective and less time-consuming possibility for producing individual abutments. Individual abutments can be produced by means of a molding process which, however, has several disadvantages. It is difficult in connection with bridge and similar constructions in particular to produce an accurate shape as well as a stress-free structure. Furthermore, there is the danger of temperature-related changes of the material during molding. Individual abutments can be individually produced as individual parts, wherein they are individually made either from a blank or a plate. Finally, ready-made abutments, which are then finished or individualized, for which purpose they are fastened on a plate-shaped holding device, can also be used for the production of individual abutments. In any case, the production of individualized connecting bodies is expensive.
A large amount of time is required when producing bridges which are supported by implants, namely in connection with pushing the supra-structures on the implants and abutments. While the insertion process in the course of producing a crown-like tooth replacement, which extends only over the area of one tooth, does not have too many problems, it is considerably more problematical when providing a bridge-like tooth replacement extending over the area of several teeth, since in this case the supra-structure is indirectly supported on several implants and directly on several abutments. The implants, or respectively their longitudinal axes, are generally not arranged parallel, but diverging, and therefore require corresponding divergent insertion directions. But a supra-structure produced in one piece in the form of a bridge can only be pushed in in a single insertion direction, this means that the insertion direction on several implants, or respectively abutments, must be parallel, which at present is only possible under difficult conditions. With large divergences the placement becomes impossible, or becomes only possible when manual finishing work has been performed, which requires a large outlay. With lesser divergences it is still possible to perform the placement in the mouth of the patient, however, only by the generation of large stresses of the implants and/or the abutments and/or the supra-structure.
It is extraordinarily difficult at present to obtain a stress-free structure with unchanged material properties of the tooth replacement with the conventional methods.
It is therefore the object of the invention
to propose an improved method for producing an individual, implant-supported tooth replacement, and
to propose an improved method for producing an individual tooth replacement element, i.e. an individual tooth replacement element made of one or several elements, which can be mounted on at least one implant or at least one tooth stub.
For producing the tooth replacement, a negative impression, or respectively a negative impression of the jaw or jaw area in which the tooth replacement to be produced will later be placed, is made by the dentist, the same as in connection with conventional methods, in order to obtain information regarding the position of the base, or respectively the implant or implants. A working model is made by the dental technician on the basis of this negative impression. A manipulation implant arrangement, whose position corresponds to the implants in the mouth of the patient, is subsequently attached. The manipulation implant arrangement can consist of one or several manipulation implants corresponding to the number of actual implants. The manipulation implants do not or hardly project out of the working model, the same as the implants do not or hardly project out of the corresponding jaw area of the patient. Therefore an auxiliary element is provisionally attached to each manipulation implant. These auxiliary elements project out of the working model and constitute auxiliary elements, or respectively measuring elements, because they reproduce the insertion depth, the direction of the longitudinal axes and the angular position of the manipulation implants in the working model, and therefore also the implant depth, the axial direction of the implants and the angular position of the implants in the mouth of the patient. With the aid of these auxiliary elements or measuring elements it is subsequently possible to acquire data regarding the geometry of the working model, from which it is possible to draw conclusions regarding the exact position of the implants in the jaw area of the patient. Further data can be determined from the data once acquired, which are needed for the fully automated production, as well as for the determination of the insertion direction of the further components of the individual tooth replacement. In particular, it is possible to produce the components of a tooth replacement containing several implants in such a way, that placement can take place in a single insertion direction, which is also called a parallel insertion direction. In this way a degree of precision, which up to now had not been attained, is achieved in every respect.
The production in accordance with the invention of a tooth replacement element by the novel method is essentially the same as the production of a tooth replacement, with the exception of the method steps which solely relate to the implants, since tooth replacement elements are supported either on existing tooth stubs or on implants which are considered to exist.
Further details and advantages of the invention will be described in what follows by means of exemplary embodiments and while making reference to the drawings.