WO2008145687A1

WO2008145687A1 - Method and devices for producing a model of a patient's dentition

Info

Publication number: WO2008145687A1
Application number: PCT/EP2008/056595
Authority: WO
Inventors: Paul Rosenhain
Original assignee: Luntscher, Nikolaus
Priority date: 2007-05-29
Filing date: 2008-05-29
Publication date: 2008-12-04
Also published as: DE102007025164A1

Abstract

According to the invention, in order to avoid the occurrence of internal stresses during the moulding or casting of the shapes that are to be moulded, it is proposed that the object whose position and orientation are to be transferred with particular precision is initially excluded, by a soft spacer, from the moulding or casting known from the prior art. This allows the moulding or casting material to harden without internal stresses being able to build up in the area of the object, since the object does not come into contact with the moulding or casting material. The free space remaining around the object is stiffened in a further step, for example by casting the free space after removal of the spacer or by hardening of the spacer.

Description

Methods and apparatus for creating a model of a patient's dentition

The invention relates to a method and devices for creating a model of a patient's dentition, in particular for the preparation of attachable to implants dentures.

In the creation of dentures in general by dental technicians this modeled on a dented by the dentist tooth stump or implant stump in previously created plaster model a true to the original wax model of the tooth to be produced. However, the accuracy of the impression of the patient's dentition are certain limits. For example, the impression already exists, i. H. the negative shape of the patient's denture based on silicone, polyether or alginate materials fraught with errors. The aforementioned materials are subject to u.a. thermal reactions during setting, which lead to residual stresses. After lifting, these residual stresses naturally lead to deformations in the negative impression. Furthermore arise when lifting the just set off impression of the jaw low but irreversible upsets in the impression material, which provide when removing the jaw of the patient for further inaccuracies, especially since when removing and undercuts are overcome. The inaccuracies occurring are uncritical in many areas of dental technology, since after introduction of the denture, z. As the crown, the bridge, etc., which can give in contact with teeth in certain limits.

Particularly problematic are the above-mentioned inaccuracies, however, in implants. Implanted dentures consist of up to three components: an artificial root (implant) that is inserted into the jawbone by the dentist, a connecting piece (implant post) and an artificial dental crown or the bridge or denture that is manufactured in the dental laboratory. The implant usually consists of the metal titanium and is manufactured in the form of a screw or a cylinder and is between 8 and 16 mm long. On this tooth root, a connecting piece, so the implant post with the tooth crown or bridge or prosthesis is strengthened. The connector is also made of titanium or ceramic, the Tooth crown or bridge is made like a conventional metal or ceramic veneer crown or ceramic. The disadvantage here is that the implant used in the jaw can not give in or avoid dents, but is rigidly fixed in the bone. Therefore, inaccuracies in the - necessarily two-fold - impression of the patient's dentition can not be compensated and cause the prosthesis is useless.

To create the negative impression (1st impression) of the patient's teeth, the following steps are necessary:

Placing a transfer post on the implanted implant in bone by means of a guided through the transfer post fixing screw;

Adjusting an individual impression tray with recesses so that the free ends of the transfer post with the fixing screw after completed

Imprint are accessible;

Filling the individual impression tray with impression material (usually silicone). - Pressing the filled with impression material individual impression tray against the

Pine, so that the transfer posts are embedded in the impression material.

Exposure of fixing screws by removing excess

Impression material; - curing the impression material.

Loosen the fixing screw so that the transfer post is no longer with the

Implant is connected; and

Peel off the transfer tray with impression material and embedded therein

Transfer post.

Through the above steps, the impression or negative form was created.

To create the plaster model from the negative mold, the following additional steps (2nd impression) are required:

- Connecting a so-called model analog, so an implant replacement set to replace the original implant in the gypsum model and has identical connections for the transfer post and the fixing screw as an original, with the transfer post by means of fixing screw; Building a gum mask, z. B. by means of silicone material as gum substitute in the negative mold, optionally after pre-isolation of the impression material;

Pouring out the negative mold so that the gingival mask and the model analog (implant substitute) are embedded in the plaster;

Hardening of the plaster while fixing the model analogue; and

Loosen the fixing screw and remove the spoon together with

Impression material and embedded transfer posts.

The gypsum model now has the embedded model analogues that are visible in recesses in the gingival mask. The dental technician can now insert the abutment posts / implant posts and model the tooth or prosthesis or bridge.

There are a number of other analogous applications with comparable accuracy problems, to which the invention can be transferred analogously. In detail:

In particular, the invention also relates to a method and devices for creating a master model of the jaw situation of a patient for the preparation of dental prostheses with double crowns / superstructures on implants.

For the production of a high-precision working model by means of elastomers (thiokols, siloxanes, polyether gums and vinyl polysiloxanes) a so-called individual spoon is recommended. It will effectively counteract volume changes caused by thermal expansion coefficients and set shrinkage.

In the precision impression with prefabricated and torsion-proof individually prepared, adapted to the impression object tray, endogenous stresses in the layer thickness of the impression material lead to dimensional changes in the impression. This leads to the transfer of false information of the jaw situation on the master model, which thus no longer match, d. H. are no longer in relation. The model is not distortion free and does not represent a dimensional representation of the jaw situation.

This discrepancy is correspondingly problematic, particularly in the case of impressions of implants, since the implant positions no longer correspond to the jaw situation due to an incorrect impression and there is an incorrect positioning with the transfer take the master model. There are not coherent corresponding model analogues with the implants in the jaw.

Impression materials shrink concentrically, if they are free in the room, z. B. if they do not adhere to the impression tray by adhesive means or mechanically. This results in a reduction of the negative form result. If the impression material is fixed to the impression tray, it will eccentrically shrink towards it and lead to an enlargement of the negative form; the model is oversized. The greater the layer thickness and amount of the impression material compared to the volume of the body to be shaped, the greater the absolute increase of the model volume.

Precision impressioning sets the standard for the work piece on which dentures are manufactured. The accuracy of fit of a superstructure is in relation to the specification, which, however, does not exclude endogenous tensions of the impression. Thus, the transfer and fixation of a model-accurate superstructure on the implants in the jaw only by manipulation of the design, impression or model is possible.

Dentures are created manually or more often using the machinery and CAD-CAM in very different designs and production methods, depending on the needs and purpose of the patient. Dentures are manufactured as fixed, removable, and conditionally removable constructions. Known are: crown, bridge and full denture. These are either made of only one material or are combined in combination of several materials. For this purpose, biocompatible materials are preferably used, such as special plastics, precious and non-noble metals, in alloy or as pure metal and ceramic and zirconium dioxide. In the production of very different production practices and procedures and special equipment in use, the conventional prosthetic production of machine production is increasingly being replaced.

In the dentures manufacturing, z. B. crown, a true-to-life tooth model made of wax or plastic of the tooth to be produced is modeled manually in 1: 1 on a previously prepared gypsum or plastic abutment or implant abutment and then in metal casting technology, or from ceramic presstechnisch, also stratification technology , or made of plastic press, cast or stratified. Disadvantageously, numerous production factors lead to non-constant results in dentures in all areas of dental technology Laboratory productions. Special skills and material knowledge are required in addition to general expertise in the production of dentures. Physically caused negative process developments as well as chemical influences lead despite many years of experience again and again to errors in manually created dentures. Manual production is limited in time and, last but not least, qualified personnel are also expensive. The computer-aided manufacturing is cheaper and very advanced. For all indications of restorative dentistry, it offers variable internal and external systems for the production of modern dental prosthesis products for almost all possible solutions in all imaginable materials.

CAD-CAM processes are increasingly replacing faulty manual production. Trendy production methods today also allow the use of special materials with advantageous properties, such as the pure titanium, which industrially produced as a block for CNC production has no casting impurities and porosities and harmonizes well with identical titanium implants implanted. In addition, it does not lead to negative ion migration and bone destruction by electrolysis.

Metal-free dentures is a desired goal in dentistry. This requires special, break-resistant stable ceramics, which can be done with the zirconia material optimally. Since their introduction in 1998, constantly improved computer systems and software enable novel solutions with meaningful designs and expand the range of dental prostheses. The well-known advantages of zirconium dioxide have been taken into the dental field due to already proven hip implants, which have been successfully used clinically for years. Nevertheless, the relatively short testing phase predicts good expected results with metal-free dentures, as with the delicate scaffolds.

Particularly in the field of implantology, this ceramic material offers decisive aesthetic advantages over metallic, light-absorbing constructions. Zirconia has excellent material properties and allows stable, relatively delicate constructions because of their enormous strength. The CNC production enables wide-span all-ceramic constructions that fit perfectly on the model. In implantology, it has therefore also become the drug of choice, as it is also unlike titanium plaqueunanfällig. Added to this are the prefabricated components produced from the metal and novel materials with material properties that are especially suitable for this purpose, which are very difficult or even impossible to produce in the laboratory. Of decisive advantages are the reproducible results with excellent fit results and exact products of consistent quality. These production methods are cheaper due to external outsourcing. As plasters and plastics for almost all system-related model materials also develop according to the usual impression techniques, the actual problem of non-corresponding model analogues and implants is still present.

Regardless of the way in which the prosthesis is produced, it fits snugly on the model. When creating dentures in CAD-CAM, e.g. also in rapid prototyping, a transfer is made from the dental stump or implant abutment ground on a previously created model made of gypsum, plastic or material suitable for the respective applied system after virtual digital acquisition by scanning with a laboratory scanner or externally when using 3D planning with computed tomography designed for a true to original model of the tooth to be produced with appropriate computer software and hardware.

The digital data acquisition and transfer to the working model does not call into question the type of impression, but rather the deformation reactions from the working model creation, since contractions such as expansions in the material do not reproduce the created fit of the dentures on the jaw. In the copying process, the transfer takes place by means of manual scanning or, as with CEREC System Sirona, with the corresponding hardware and software. Again, the production of dental prostheses after an impression and Arbeitsmodellherstellung done.

The accuracy of the impression of a patient's denture, however, certain limits. For example, the impression, ie the negative form of a patient's dentition based on irreversible elastomeric impression materials such as A-silicones and polyethers, as well as reversible hydrocolloids and water-based alginates, is already flawed. The abovementioned materials and virtually all known impression materials are subject to thermal reactions which lead to residual stresses during the setting process. During the setting process and after lifting, these residual stresses naturally lead to deformations in the negative impression. Furthermore arise when lifting the just set off impression of the jaw low but also irreversible upsets in the impression material, which provide when removing the jaw of the patient for further inaccuracies. In particular, since the removal of undercuts and non-parallelism are overcome, which can not prevent even with the best possible compliance with the recommended 4 mm space between teeth and Abdrucklöffelwand this as well. The deformation of the impression material must not exceed 30%. Otherwise it comes to an irreversible compression. The taken from the literature speaks for itself.

Although the maximum recovery of impression material is stated to be up to 98%, the 2% non-recovery also represents a dimension change that has a three-dimensional effect and leads to the greatest difficulties in the transfer of fits in implant prosthetics. The inaccuracies occurring are not uncritical even with natural teeth in dental technology, even if after insertion of the denture, e.g. a crown, bridge, etc., which can give in contact with teeth in certain limits because of the elastic periodontium apparatus. Thus, too short and too long crowns, such as too narrow or too wide marginal closure, can result from the above-mentioned 2% non-return. The above-mentioned inaccuracies are especially problematic in implants prosthetics.

Dentures worn on implants, so-called superstructure, consists of several components. A superstructure is superimposed on the implant. The number of implants determines the extent and construction type, which also requires appropriate construction in connection with natural tooth roots, or prepared natural dental abutments. The implant is inserted into the jawbone by the dentist or surgeon, surgically inserted or implanted. Multi-part implants are connected via a connector (implant post or abutment) to the tooth crown, bridge or denture.

Implants are usually made of the metal titanium, which is particularly well suited for this and clinically well proven. Aesthetic advantages are offered by zirconia-made implants, which are manufactured in one piece with the implant abutment for technical reasons. A distinction is made in implants one-piece and multi-part components, one-piece so-called single-phase implants consist of one part, namely the artificial tooth root with tooth stump. Multi-part or multi-phase implants consist of several components and are sometimes combined in combination with titanium and zirconium dioxide or other combinations with biocompatible material components. In the Implantabauforrmen exist several systems that are designed very different; These can be made in the form of a screw or a cylinder and are between 4 to 16 mm long.

In the case of multi-phase implants, the tooth root is fixed via a titanium screw in the interior via a connecting piece with the implant post. Other systems fix per

Snap closure. About the abutment of the dentures is the crown, bridge or

Prosthesis fixed, or even removable from the patient or even limited in the

Dental practice removably attached.

The connector can also be made of titanium or zirconium dioxide. The denture crown, bridge or denture is made in a conventional manner and mounted on the implant or implants.

The disadvantage, however, is that while the implant used in the jaw can not give in or avoid dodging, but rigidly stores in the bone. Therefore, inaccuracies in the - necessarily double - impression of the patient's dentition can not be compensated.

It is not possible to easily integrate perfectly fitting constructions, which are precisely made on the model or via CNC, with non-corresponding model analogs and implants of a patient jaw. The implant systems lead to overcoming the problem of fitting special, very precise Ausbelichteile which connect with composites on the model or in the mouth, the individual elements glued. Prostheses and bridge constructions are prepared for this purpose by appropriate consideration in the production for this addition.

In order to solve the known problem of fitting, very complex procedures, such as the SAE Secotec spark erosion method in the dental laboratory, are also used in implant technology. The spark erosion serves the elimination of metallic interfering contacts when dentures. Field of application of the method are primarily the superstructures and bars for Implantverblockung. This and the Cresco method, in which the non-conforming basal surfaces of the construction are separated and, after fixation by means of laser correction, are added again clarify the subject of the fitting difficulties. This effort, like all other techniques, can not help the relation between model and jaw situation, the actual problem of inaccuracy. Although on the model dentures it does not fit in the mouth, if identical specifications are not available.

Thus, for years, oral contraception has been the only alternative for achieving complacably useful results. The established method originally came from the electroplating industry and allows the joining of the construction elements orally. For this purpose, the superstructure is built with tilt-free clearance fit the so-called

Secondaries with the tertiary structure in the patient's mouth with special adhesives,

Bonded composite adhesive. The bond and the composite seal the glue joints. The so-called tricolor effect in the area of the adhesive bond is unavoidable depending on the construction.

Likewise, so-called transmission key to prevent oral contraception, which serve in the patient's mouth for connecting and transmitting fixed individual components of a superstructure. This transfer method, which is known from double-crown technology, is also used orally with plastic as a joining material, and in the laboratory the current situation is reproduced on a newly created model. This principle, which is correct in principle, can not provide useful models either, since this also leads to deformations due to contraction and / or expansion of the model materials used, and thus to a change in position. Tensions in the constructions are noticeable in the mouth.

The goal of a master model is to enable precise dental prosthesis production. For this, the conditions of a correct impression and exact model production must meet the requirements.

The invention is therefore based on the object to provide an improved method and devices for creating a model of a patient's dentition.

This object is achieved by a method or devices having the features of the independent claims. Advantageous embodiments of the invention are the subject of the dependent claims.

According to the invention, in order to avoid residual stresses occurring during the molding or pouring out of the molds to be molded, it is proposed that the object whose position and orientation should be transmitted particularly accurately be first excluded from the known from the prior art impression or pouring by a soft placeholder. Thus, the impression or Pouring a curing, without that can build up residual stresses in the area of the object, since the object does not come into contact with the impression or Ausgießmasse. According to the invention care must therefore be taken to ensure that a clearance remains around the object during the curing of the impression or pouring material. The remaining space around the object is stiffened in a further step, for example by pouring the space after removal of the placeholder or by curing the placeholder. Because the volume of the free space is very small in relation to the volume of the total impression or spout, only comparatively low residual stresses and thus potential inaccuracies can build up. The inevitably associated with each hardening acting on the object deformations are thereby smaller than in an impression or spout of the known type. It can be selected at the same time on a shape to be shaped and transferred according to the method several objects.

To carry out the method, it may be necessary for the object to be permanently but detachably connected to the mold to be shaped, since it is fixed in the impression or pouring material after the free space has been stiffened. Therefore, the method according to the invention is particularly suitable for the creation of a model of a patient's dentition for the preparation of dental prostheses that can be fixed on implants. In this case, two impressions are made, namely a first impression in which the patient's teeth form the abzuformende form and a transfer post is provided as an object, which on a bone of the patient's dentition fixed implant is releasably attached, and a second impression, in which the in the first Molding molded negative mold forms the mold to be molded and a so-called model analog is provided as an object which is releasably secured on a fixed in the negative form of the transfer post.

The purpose of these steps is for the implant in the jaw to have the same position and orientation as the model analog in the model, or to correspond identically. Accordingly, the teaching of the invention can also be applied to other situation impressions for the creation of dental prostheses, z. B. crowns, double and multiple crowns transferred. In this case, the patient's dentition with framework forms the form to be shaped and the framework crown detachably connected to it forms the object. The fixation described by means of fixing screws (in the so-called open mouth impression by means of spoon with recess) is only one possibility of the embodiment of a releasable fastening means between form and object to be formed. It is also possible to select one-click, snap-on or snap-in connections. These allow a so-called closed mouth impression, in which the form attachable transfer caps are embedded in the impression compound using a conventional impression löffeis. This needs no recesses.

If a reactive material is used as a placeholder, which only hardens when the impression or pouring material has already hardened, the impression tray need not contain any recesses, i. H. the placeholder does not have to be accessible. It thus eliminates work steps. The reactive material is preferably activatable in such a way that it begins to cure with a time delay upon contact with the impression or pouring material. The time delay is to be selected such that after contact first the impression or pouring material hardens and the placeholder only then hardens. As a result, each primary structure can be accurately embedded by the impression according to the invention:

The method is suitable for embedding any object or primary structure which is permanently but detachably connected to the mold to be molded.

There are also so-called functional imprints feasible. In this case, a primary structure, for. As a crown frame, initially placed in the mouth on the tooth stump or the implant and taken a first impression. Here, the primary structure serves as an object, which is provided with a placeholder before the impression. Since it is a closed impression, the inaccessible placeholder must consist of the above-described reactive material. It stays soft while the impression hardens and only then hardens itself. In the second spout of the newly formed negative mold, in which the primary structure is embedded, the primary structure is first with a suitable fixation z. B. the common double pin provided. The latter serves as an object and is provided in accordance with the invention with a corresponding placeholder.

For a better understanding, the individual method steps and advantageous embodiments will be explained later with reference to FIGS. 1 to 4 by way of example with implants.

The method can also be carried out when the object is firmly and permanently connected to the shape to be molded. A prepared tooth stump or implant-attached abutment may be such an object. After stiffening the free space then the impression can be deducted together with the stiffened space. According to the invention, the devices required for carrying out the method are also claimed. The use of an elastic sleeve as a placeholder allows the dentist or dental technician quickly and without much work, the placeholder on the object, so usually apply the transfer post or the model analog. An industrially manufactured prefabricated sleeve as a placeholder also offers the advantage of great regularity, so that the volume to be cured later is very uniform, in particular rotationally symmetrical. The spout thus has a substantially equal wall thickness around the object. The small remaining residual stresses or shrinkages due to contraction or expansions upon expansion therefore occur essentially symmetrically, so that the inaccuracies caused by shrinkage or expansion remain very small. This is an advantage over the individual modeling of a wax sleeve on the object. The elastic design of the sleeve allows easy sliding onto the object and also the unproblematic pulling out of the cast-in placeholder. This must namely be pulled out between the object and the potting compound.

In a further advantageous embodiment, the placeholder is configured self-centering with respect to the object. This compensates for the residual stresses occurring during curing. A self-centering sleeve, for example, be realized by the fact that inside lamellas, in particular tapered inward Lammellen, z. B. in triangular form, extend. After putting on the object, for example, a transfer post, model analog or a framework in crowning technique, and short twisting of the sleeve, this is applied symmetrically to the object. Slats also allow such a placement on objects with irregular cross-section (eg oval, rectangle, triangle, any cross-section) in accordance with compliant outer walls of the sleeve. The outer walls follow the shape.

A further advantageous embodiment provides an anti-rotation in relation to the outer surface of the placeholder. This prevents the sleeve from accidentally twisting. An anti-rotation can also consist in that the cross section of the applied placeholder deviates from the circular shape, that is, or triangular or oval. The cross section may be a property of the placeholder or arise only after placement. As a result, the spout thus has a substantially equal wall thickness around the object Advantageously, the placeholder is made as an endless tube, that is, all elements, such as lamellae, recesses or notches are uniformly parallel to the longitudinal axis. This allows economical production as an endless tube z. B. by extruder. Also, an economical production by injection molding is possible, so that eliminates the necessary during extrusion section.

From the point of view of the dentist or dental technician comparatively little changes in the known process when molding when the objects, for example, transfer post and model analogue already exist with placeholders, so factory made with the same. This also has the advantage that by suitable measures, for example detachable bonds, etc., the placeholder is aligned particularly precisely symmetrical to the object.

A particularly user-friendly design provides for a curable placeholder. This is so soft in the ground state that when curing the Abdrucksbzw. Pouring material barely, or no voltages can be transmitted to the object surrounded by the placeholder. Only after the curing of Abdruckbzw. Spout material activates the hardenable placeholder and hardens. Known activations are in particular chemical activation and UV irradiation. The big advantage in terms of application technology lies in the fact that hardly anything changes for the dentist or dental technician during implant impression. The intermediate step "curing by UV irradiation" is only necessary after the curing of the impression or pouring compound, and for the patient, the procedure used so far is merely extended by the times for the curing of the placeholder Of course, the curable placeholder, once connected to the object at the factory, need not be slid on, but may rest against the object inside, so the placeholder essentially encloses the object.

In practical experiments it was found that under unfavorable conditions the placeholder can be difficult to remove. In the first impression, the sleeve-shaped placeholder can be sunk too deep in the tray and / or run full of impression material. In the second impression can rest so tight after grinding the plaster that the edge of the placeholders is difficult to reach and / or the placeholder with plaster run out. The following advantageous embodiments of the wildcard were found to eliminate the problems: The placeholder is cup-shaped or has a lid and therefore can not run. The thickness of the lid is to be dimensioned such that it protrudes over the impression tray edge or flush during the first impression and / or predetermines the model base height during the second impression or has the necessary thickness for grinding or material thickness at low fixation. Optionally, the lid handling means, for. B. tabs, holes, notches, which allow in the enclosed state to extract from above with a tool or by hand the placeholder. The lid may be permanently connected to the placeholder sleeve, in particular be integral with the placeholder. A self-closing opening, z. As a narrow slot or partially overlapping shapes or surfaces, that allows

Perform an instrument, eg. As screwdriver, to operate the hidden by the placeholder fixing screw without mass can penetrate. When the lid is removable, it is preferable to provide an outer border surrounding the upper outer wall of the sleeve. After removing the lid, the upper wall piece of the sleeve is exposed and can be taken. A pin pointing downwardly in the inner part of the lid for insertion into the opening of the sleeve centers and secures the lid against the sleeve. The advantages of outer border and tenon can also be combined. The lid can only partially, d. H. be hinged, connected to the sleeve, such that it is hinged. The opened lid thus serves as a handling means, optionally, the

Placeholder can be pulled out by pulling on the open lid by pulling with your hand. The wholly or partially attached lid is preferably made in one piece with the sleeve, for. B. in the pressure injection molding, or by casting on the sleeve. It can also be glued on. Finally, in addition to or as an alternative to the above, a perforation extending through the sleeve is proposed, which runs in a vertical direction or, preferably, spirally from top to bottom. When pulling out, the sleeve can thus dodge inward and can be removed with less force. The above also applies to the placeholders used in the second impression, which are attached to the model analog. It does not penetrate plaster and the sleeves can be better grasped thanks to the lid.

Further advantages will become apparent from the following description and the accompanying drawings. Likewise, according to the invention, the features mentioned above and even further can be used individually or in any desired combinations with one another. The mentioned embodiments are not exhaustive and have exemplary character. Showing: Figure 1 implants with attached transfer post in the jaw before

footprint;

Figure 2 shows the situation of Figure 1 after the impression;

FIG. 3 shows the impression from FIG. 2 after transfer to a plaster model with placeholders placed on the model analogue;

FIG. 4 shows the finished plaster model;

FIG. 5 shows a placeholder; and

Figure 6 various alternative embodiments of the placeholder with cover.

Figure 1 shows in the jaw 9 screwed conventional implants. The dentist has so-called transfer posts 11 by means of a in the upper part of the

Transfer post 11 accessible fixing screw 12 screwed to the implants. A previously individually made impression tray made of plastic 7 was first placed on the sample to check whether the fixing screws 12 fit through the introduced into the impression tray 7 recesses 71. The lower side of the impression tray 7 in FIG. 1 is then filled with impression material, for example silicone, and pressed onto the patient's jaw 9 under pressure.

FIG. 2 shows the situation after the impression. Between impression tray 7 and gum 6 is now the cured impression material 51 made of silicone. The second implant 10 from the right shows the placeholder 3 placed on the transfer post 11 before the impression, which creates a free space 4 next to the transfer post 11 into which no impression material 51 has penetrated. After hardening of the impression material 51, the spacer 3 forming the sleeve can now be pulled out, so that subsequently the free space 4 can be poured 53. This may be a different material than the impression material 51 or the same material. It is crucial that when curing the impression material 51 no stresses on the transfer post 11 could be transmitted. At the latest with the removal of the placeholder 3, the transfer post 11 is completely stress-free because of the free space 4 surrounding it. The implant on the right in the figure shows the state with free space 4 filled with silicone 53. The removal of excess impression material on fixing screws 12 and placeholder 3 in the area of the recesses 71 of the spoon 7 takes place before setting or hardening of the impression compound 51.

Now the dentist can loosen the fixing screw 12. The impression consisting of spoon 7, impression material 51, hardened filling 53 of the free space 4 and therein enclosed transfer post 11 can now be lifted off the gum 6 and implant 10.

FIG. 3 already shows the casting from FIG. 2, the underside of the transfer posts 11 having been rigidly connected to model analogs 21 by means of the fixing screw 12. Thereafter, a gingival mask 61 made of silicone was modeled on the impression material 51, 53 in the usual way. After that again placeholder 3 are used; However, these are this time attached to the model analogues 21, ie those components that replace the implant 10 in the model. As known from the prior art, then the negative mold thus formed with gypsum 52 or other application-suitable materials, for. As plastic or epoxy resin, poured out during curing, the inevitable shrinkages because of the placeholder 3 and created by this free space 4 are not transferred to the model analogues 21. Then, the placeholder 3 are pulled out again and thereby resulting comparatively small and uniform space 4 is poured out, for example by plastic 54th

The application example shown here with several model analogues shows that it is also preferable first to remove certain wildcards and to empty the freed up space, while other wildcards initially remain on the object. These are removed only after curing of the pouring mass. This makes it difficult for the negative mold to slip, as all objects are never exposed at the same time. Because the placeholders always cause a certain fixation.

FIG. 4 shows the model analogues 21 cast in plastic 54 in the finished model. For this purpose, the fixing screws 12 were again solved, so that the impression tray 7 with impression material 51, 53 and embedded therein transfer posts 11 could be removed. The dental technician can now place the implant posts (not shown) on the model analogues 21 and begin the construction of the tooth.

FIG. 5 shows a placeholder 3 according to the invention made of a soft, elastic material, for example Silicone. The substantially cylindrical spout 3 is hollow on the inside and has a plurality of inwardly directed fins 31, which taper inwardly, the grommet 3 therefore centers itself when it is pushed onto a suitable object. Notches 32 are provided on the outer wall of the spout as anti-rotation. Preferably, these lie along individual or all lamellae, so that the thicker wall thickness of the nozzle in the region of the lamellae can be used for the notches. The wall thickness W can therefore remain low, resulting in reduced Internal stress leads and where the spout can be easily bedded. Similarly, outward-facing slats or other raised shapes such as rounding for rotation security are possible.

The lamellae 31, as well as the notches extend in the longitudinal direction of the spout, so that it can be manufactured as a continuous strand, in particular by extrusion.

Fig. 6 shows implants 10 in the first impression with placed on the transfer posts 11 different placeholders 3 next to the transfer post 11 create a free space 4, in which no impression material 51 has penetrated. These have according to the invention covers 310, 320, 330 and 340. After hardening of the impression material 51, the placeholders 3 can now be pulled out, so that subsequently the free space 4 can be poured out.

The first placeholder 3, 310 from the left is cup-shaped, d. H. the known from Fig. 2 sleeve 3 is closed at the top by a lid, which is connected in the embodiment in one piece with the sleeve. He therefore can not run. The lid protrudes from the spoon 7. A selbstverschließende opening 311, here a narrow slot, allows the implementation of an instrument, for. As screwdriver, to operate by the placeholder 3, 310 concealed fixing screw 12. This opening can be used with all lids, but only exemplified here.

The third placeholder 3 from the left has a separate cover 330 with outer border 331, which comprises the upper outer wall of the sleeve 3, that is free from impression material. After removing the cover 330, the upper wall piece of the sleeve is exposed and can be taken.

The fourth placeholder 3 from the left has a separate lid 340 with inner pin 341 which centers the lid against the upper opening of the sleeve 3 and fixes the lid to the sleeve.

The second patz holder 3 from the left demonstrates a separate lid 320 that combines the benefits of the outer perimeter 321 and peg 322.

The lid 320, 330, 340 of the second, third or fourth placeholder may also be hingedly connected to the sleeve 3, such that it is hinged. The opened lid thus serves as a handling means, optionally, the

Placeholder can be pulled out by pulling on the open lid by pulling with your hand.

Claims

CLAIMS:

1. A method for creating a model of a patient's dentition wherein impressions and / or pouring are made of a form to be molded, with the following steps:

a.) selecting an object (2) on the mold (1) to be formed; b.) Providing the object with a placeholder (3), which is such that in the subsequent impression or spout, a free space (4) is formed, which is substantially free of impression material (51) or spout material (52), wherein the Placeholder is surrounded by impression material or spout material. c.) applying the impression material (51) or pouring material (52) onto the mold; d.) curing the impression material (51) or pouring material (52) and then e.) Stiffening of the free space (4) and thereby fixation of the object with respect to the cured impression material or pouring material; and f.) removing the impression material (51) or pouring material (52) together with the stiffened free space and preferably the object of the shape to be molded.

2. A method for creating a model of a patient's dentition for making fixable on implants (10) dentures, with a first impression, wherein the patient's dent the abzuformende form (1) and a transfer post (1 1) is provided as an object (2) which is releasably secured to an implant (10) fixed in the bone (9) of the patient's dentition, comprising the following steps:

a.) selecting a transfer post (11) on the patient dentition to be formed; b.) Providing the transfer post with a placeholder (3), which is such that the subsequent impression, a free space (4) is formed, which is substantially free of impression material (51), wherein the placeholder of Impression material is surrounded; c.) applying the impression material (51) on the patient's dentition; d.) curing the impression material and then e.) stiffening the free space (4) and thereby fixing the transfer post with respect to the cured impression material; and f.) removing the impression material (51) together with the stiffened free space and the transfer post from the patient dentition to be resected.

3. The method according to any one of the preceding claims, wherein the impression material

(52) is placed on the patient's dentition using a spoon, in particular an individual tray (7), and is continuously connected to the tray while performing steps c) -f), comprising the step of: - applying the impression material (51) on the spoon (7),

4. The method according to any one of the preceding claims, wherein the spoon is designed such that step e) is feasible and between step e) and f) the transfer post (1 1) can be released from the implant, with the following step between step e) and f):

- Release the transfer post (1 1) from the implant (10).

5. The method according to any one of the preceding claims, wherein the transfer post at its upper end a fastening means, in particular a fixing screw (12) for releasably securing to the

Implant has, with the following step:

- Making an individual spoon (7) and introducing recesses (51) in the same for the transfer post (1 1) and / or attachment means (12).

6. A method for creating a model of a patient's dentition for making fixable on implants (10) dental prosthesis, with a second impression in which the previously formed by the patient denture negative mold forms the shape to be molded (1) and a model analog (20) as an object (2 ) is provided, which on a fixed in the negative mold (9)

Transfer post (11) is releasably secured, with the following steps: a.) selecting a model analogue (20) on the negative form to be formed; b.) providing the model analogue (20) with a placeholder (3) which is such that during the subsequent pouring, a free space (4) is created that is substantially free of pouring material (52), the placeholder being surrounded by pouring material; c.) applying the spout material (52) in the negative mold; d.) curing the spout material and then e.) stiffening the free space (4) and thereby fixing the model analog (20) with respect to the cured spout material; and f.) removing the spout material (52) together with the stiffened one

Free space and the model analogue (20) of the negative form to be formed.

7. The method of claim 6, wherein the transfer post at its upper

End has a fastening means, in particular a fixing screw (12) for releasable fastening with the model analog (21), with the following

Step between steps e) and f): - releasing the transfer post (11) from the model analogue (20).

8. A method for creating a model of a patient denture for the preparation of on implants (10) attachable dentures, comprising a first impression according to one of the preceding claims 1-5 and a subsequent second impression according to one of the preceding claims 6-7.

9. The method according to any one of the preceding claims, wherein as a spacer (3) a modeled wax layer is used, which is in particular rotationally symmetric, wherein the step d) for stiffening the free space comprises the following steps: d1) melting out of the placeholder (3) from the spout material (52); d2) filling the freed space (4) with a pouring mass

(6); and then d3) stiffening the pouring mass (6).

10. The method according to any one of the preceding claims, wherein as a spacer an elastic sleeve, in particular a rotationally symmetrical sleeve is used.

11. The method according to any one of the preceding claims, wherein the elastic sleeve is configured such that it can be pushed onto the object in step b).

12. The method according to any one of the preceding claims, wherein the step e) for

Stiffening of the free space comprises the following steps: d1) pulling out the placeholder (3) from the impression material or pouring material; d2) filling in the freed space (4) with a pouring mass (6); and then d3) stiffening the pouring mass (6).

13. The method according to any one of the preceding claims, wherein the placeholder (3) is soft in the ground state and can harden activatable.

14. The method according to any one of the preceding claims, wherein the step e) for stiffening the free space (4) comprises the following steps: d1) activating the placeholder (3) in the impression material or pouring material; d3) stiffening the placeholder (3) in the impression material or pouring material

15. The method according to any one of the preceding claims, wherein in steps a) and b), the object (2) has been provided with the placeholder (3) before it comes into contact with the shape to be molded.

16. placeholder, in particular for carrying out the method according to one of the preceding claims.

17. placeholder according to one of the preceding claims, wherein the placeholder

- Is so elastic that it can be pulled out of a potting compound;

- consists of materials that do not form a chemical bond with the potting compound;

- tubular;

is self-centering, such that when pushed onto an object of the placeholder centered with respect to an object, in particular by means of inwardly extending slats;

- On its outer lateral surface an anti-rotation, in particular in Has longitudinally extending recesses or bulges; and or

- Is essentially rotationally symmetrical.

18. placeholder according to one of the preceding claims, wherein the placeholder (3) in

Ground state is soft and hardens after activation.

19. object, namely primary structure, in particular transfer post,

Model analog or framework for dental crowns with a placeholder according to one of the preceding claims.