DE29600346U1 - Device for carrying at least one tooth model - Google Patents

Description

Kerr Corporation, 28200 Wick Road, Box 455, Romulus, Michigan 48174, U.S.A.

Device for carrying at least one dental model {model carrier}

The invention relates to a device for carrying at least one tooth model (model carrier) with a substantially rigid base body which has a bottom side and a top side to which a tooth model can be attached.

Model carriers of various designs are used in the field of dental technology to hold models of individual teeth or several teeth in a dental arch cast from modeling plaster, which are subsequently referred to as tooth models.

To produce tooth models, modeling plaster mixed from gypsum powder and water is poured into an impression of a patient's teeth made from an impression material. After the modeling plaster is poured into the impression, the modeling plaster hardens over time and, after hardening, is separated from the impression material to form a finished tooth model.

In order to enable or improve access to the proximal surfaces of individual teeth on the dental model, individual teeth or groups of prepared teeth on the dental model are often separated. To do this, a cut is made through the dental model.

Before the teeth or groups of teeth to be separated are cut and, if necessary, removed from the dental model, a measure must be taken to ensure that the teeth, after being removed from the dental model, can be returned to the exact position in the entire dental model in which the separated teeth were before they were separated and, if necessary, removed.

A well-known measure is to drill at least two holes in the underside of the tooth model below the tooth to be separated and also to drill at least two holes at the same distance in the model carrier to which the tooth model is attached. The holes run from the underside of the model carrier through the model carrier into the underside of the tooth model. After drilling, fixing pins can be inserted through the holes, which extend through the holes in the model carrier as well as through the holes in the tooth model. In this way, the position of the tooth to be separated is fixed within the entire tooth model. After removing a separated tooth from the tooth model, the original position of the tooth within the tooth model can be restored quite precisely by inserting the fixing pins through the holes after reinserting the removed tooth into the tooth model.

However, the separation of teeth using such model carriers and using the described measure for positioning the separated teeth when reinserting them into the model is quite time-consuming and costly.

The invention is based on the object of providing a model carrier which enables a simple and quick separation of teeth from a dental model and an exact refitting of separated teeth into the jaw model.

The object is achieved in a device of the type mentioned at the outset in that a flexible strip element is permanently attached to the base body along the underside and the base body consists of an essentially brittle material such as plaster or the like, which can be broken essentially without splinters to form slightly structured fracture surfaces.

With the help of the model carrier according to the invention, individual teeth of the dental model attached to the model carrier can be easily separated, so

that aproximal surfaces are more easily accessible and can be returned to their original position within the entire tooth model in just as simple a manner. In addition to the model carrier according to the invention, no further parts such as fixing pins or the like are required, and no preparatory work for exact positioning has to be carried out, such as drilling through the model carrier and the tooth model.

To separate a tooth, a cut is made through the tooth model attached to the top of the model carrier according to the invention between two teeth and partially through the base body of the model carrier. The partial severing of the base body and the remaining connection over the non-severed area creates a predetermined breaking point in the base body. The base body is then broken through manually. During the breaking through, structured fracture surfaces form in the area of the predetermined breaking point because the base body according to the invention consists of a substantially brittle material. By breaking through, the base body is completely separated into two partial bodies, which are, however, held together by means of the flexible strip element according to the invention attached to the base body along the underside. The strip element takes on the function of a hinge and the two partial bodies can be pivoted about an axis running through the strip element. By pivoting, the proximal surfaces of the teeth between which the cut was made become accessible.
In the manner described, several teeth of the model can be separated by making several cuts.

After swiveling or folding apart the parts of the broken base body and carrying out work on the separated teeth, the body parts are swiveled back into a position in which the structured fracture surfaces created when the base body was broken come into contact. They fit together almost seamlessly again because the brittle, largely splinter-free breakable base body material, such as plaster, does not crumble during the breaking process. As a result, after the body parts are swiveled back or folded back, the separated teeth return to the exact position within the tooth model that they had before the base body was broken.

The model carrier according to the invention can be used particularly advantageously in the case that crowns are reworked before being inserted into the patient,

in particular, they need to be reground to fit precisely into a prepared cavity of a tooth. Such reworking is often necessary when using ceramic crowns, as these shrink during the hardening process during manufacture.

To rework a ceramic crown, a model of the area around the tooth to be crowned is first made using an impression. The model of the area around the tooth to be crowned, which is attached to the model carrier, is then separated by two separating cuts and then breaking through the base body. The severed parts of the base body of the model carrier are pivoted or folded around the axis running through the strip element using the flexible strip element. The crown to be reworked can be fitted into the cavity of the separated tooth of the model. The folded parts can be pivoted or folded back into their original position. It can then be determined whether the crown fits optimally into the cavity of the separated tooth and the area around the separated tooth and whether the crown needs to be reground, for example on contact surfaces that are in contact with neighboring teeth, in order to be adapted exactly to the area.

The reworking of the crown is particularly easy and quick with the help of the model carrier according to the invention, since individual teeth of the model can be quickly separated and brought back into the area surrounding the tooth in the model. The crown to be inserted into the patient's tooth can be finished on the model outside the patient's mouth with the help of the model carrier according to the invention and then inserted into the patient's tooth without any further reworking, which means that the stress on the patient is minimal.

The use of the model carrier according to the invention is also particularly advantageous in the following application: It often happens that when attempting to fit dentures prefabricated by a dental laboratory it is discovered that the dentures fit the plaster tooth model on the basis of which the dentures were prefabricated in the laboratory, but do not fit the patient's prepared tooth stumps. The dentures can be bridges, crowns or partial dentures.

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In this case, it must be determined which tooth stumps in the patient's mouth are the reason why the denture does not fit, for example, is jammed. To do this, a new model is made from plaster using an impression on the model carrier according to the invention. Then each tooth or tooth stump of the model is separated and folded in the manner described above using the model carrier. The denture is then attached to the part of the model that is not folded. If it is determined that the denture does not fit when the tooth stump is not folded, but fits when the tooth stump is folded, it is clear that the folded stump is responsible for the non-fit and the denture can be reworked, for example ground down.

After finishing, the folded stump of the model is folded back. If the denture now fits the entire tooth model, it can be inserted into the patient's mouth. If it still does not fit, the denture can be further ground down. The tooth stumps of the model can be separated and folded down one after the other and the denture can be made to fit through finishing. In this way, the denture can be made to fit quickly and inexpensively at a dentist's chair and outside the patient's mouth. The strain on the patient, dentist and assistant is significantly reduced by the procedure described.

A particularly preferred embodiment of the model carrier is characterized by the fact that the strip element is thin in relation to the thickness of the base body, which is determined by the average distance between the bottom and top. This results in particularly good bendability and thus the ability to pivot and fold the severed parts of the base body, so that individual teeth can be separated particularly easily.

The strip element advantageously has a woven structure. This structure ensures good flexibility and at the same time low elasticity of the strip element with regard to tensile stresses applied to the strip element. This means that the separated body parts of the base body can be rotated very precisely around the pivot axis in the strip element. The separated teeth or tooth stumps of the model therefore assume the exact position they had before being severed and separated after being separated and folded back into their original position.

In a further advantageous embodiment of the invention, the underside of the base body is essentially flat and is completely covered by the strip element, whereby the strip element can be attached to the base body quite easily.

A particularly preferred embodiment is one in which the strip element is connected to the base body by means of a form-fitting connection, because such a connection is particularly secure. Such a particularly secure form-fitting connection can advantageously be achieved by the strip element having several curved, protruding hook-shaped clamping elements that are clamped to the base body. A strip element designed in this way is already available on the market as a Velcro fastener strip, which is used on a large scale to connect textile parts, so that the strip element does not have to be specially manufactured for the model carrier according to the invention, but is available relatively inexpensively.

In a further preferred embodiment, the base body is cuboid-shaped. This shape is advantageous for attaching the tooth models to the base body, since the cuboid has a flat surface, and on the other hand there is also a manufacturing advantage in that, particularly when the base body is made of plaster, the base body can be cast in a large mold in which the strip element is laid out on the bottom and the plaster is poured onto the strip element. After the plaster has been cast and hardened, several cuboid-shaped model supports can be cut out of the entire mold. This method of production is particularly cost-effective. In addition, a cuboid-shaped model support is particularly easy to handle when separating individual teeth or tooth stumps from the tooth model attached to the model support.

A curved cuboid shape of the base body is useful for producing curved tooth crowns, for example models of several front teeth.

In another particularly preferred embodiment of the invention, the top of the base body is provided with several recesses. With the help of the recesses on the top of the base body, a particularly good connection can be made between the dental model made of plaster and the model carrier. During the production of the dental model, plaster flows into the

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depressions so that a positive connection is created between the tooth model and the model carrier. The depressions are expediently either roughly hemispherical or roughly cylindrical and have a diameter of about 1 to 4 mm, because it has been shown that with this design of the depressions the flowable plaster can flow particularly well into the depressions. It is also advantageous if the several depressions are arranged in rows.

An embodiment of the model carrier according to the invention is described below with reference to the accompanying drawings. They show:

Figure 1 shows a model carrier according to the invention, on which a dental model

del!, in a partially sectioned side view;

Figure 2 shows the model carrier according to the invention from Figure 1 without the

Tooth model in a top view;

Figure 3 shows the model carrier from Figures 1 and 2 with a

severed tooth model and partially severed main body in side view; and

Figure 4 a partial body of the model carrier with tooth model as

View of a front side.

The embodiment of the model carrier 1 according to the invention shown in Figure 1 consists of a cuboid-shaped, elongated base body 2 and a strip element 4 firmly connected to the base body 2. A tooth model 6, usually obtained from a dental impression, is attached to an upper side 10 of the base body 2 and is carried by the model carrier 1. The strip element 4 is permanently attached to the base body 2 on the underside 8 of the base body 2 opposite the upper side 10.

The base body 2 consists of a rigid, brittle material such as gypsum, which can be broken to form structured fracture surfaces essentially without splinters or crumbs, so that the structured fracture surfaces formed during the breaking can be easily reassembled after the breaking due to the structure.

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The strip element 4 is thin in relation to the thickness of the base body 2, which is determined by the distance between the bottom 8 and the top 10. It completely covers the flat bottom 8 of the base body 2. The strip element 4, which has a woven structure, has, as can be seen from the sectioned right-hand part in Figure 1, protruding, elongated, curved clamp elements 12 on its surface facing the base body 2. The clamp elements 12 are firmly connected to the base body 2 by a positive connection, into which they protrude. The clamp elements 12 run essentially perpendicular to the plane formed by the strip element 4 and are more or less strongly curved at their end facing away from the strip element 4. They have approximately the shape of barbs. In the exemplary embodiment, they protrude about 1.5 to 3 mm deep into the base body. The connection to the base body by the clamp elements 12 is positively locking and also frictionally locking due to the curved shape of the clamp elements 12. The strip element 4 is designed in the manner of a woven Velcro strip, which is often used on items of clothing. The strip element 4 can be constructed in such a way that the part of the strip element 4 lying essentially in a plane below the underside 8 is made of a first textile fiber and the clamp elements 12 clamped to the base body 2 consist of another textile fiber and are woven into the first part.

The firm connection between the base body 2 and the strip element 4 is formed during the manufacture of the base body 2. To do this, the freshly produced, not yet hardened, flowable plaster from which the base body 2 is formed is placed in a mold on the bottom of which the strip element 4 has previously been placed. While the mold is being filled with the plaster, the protruding clamp elements 12 are surrounded by the plaster. While the plaster hardens, the firm connection between the strip element 4 and the base body 2 is created.

As can be seen from the sectioned part of Figure 1 and the view of the top side 10 of the base body 2 shown in Figure 2, several recesses 14 are formed in the top side 10 of the base body 2. The recesses 14 have approximately the shape of hemispheres, which in the exemplary embodiment have a diameter of approximately 3 mm. Alternatively, the recesses 14 can also be approximately cylindrical. The diameters of the hemispheres or cylinders can vary in the range of approximately 1 to 4 mm.

As can be seen from Figure 2, the depressions 14 are arranged in several rows and offset from one another on the top side 10 of the base body 2. The depressions 14 can be produced by pressing displacement bodies, which have the shape of the depressions, into the uncured, still flowable plaster from which the base body 2 is made. If the plaster has largely lost its flowability during curing or has completely cured, the displacement bodies are removed from the base body 2. The depressions 14 serve to create a firm connection between the tooth model 6 and the base body 2. The connection is created by the fact that, during the attachment of the tooth model to the model carrier, a flowable plaster from which the tooth model is cast flows into the depressions 14 in the base body 2 and the depressions 14 are completely filled with plaster.

In Figure 3, the model carrier according to the invention is shown in a state in which the tooth model 6 and the base body 2 are completely severed to form a left partial body 16 and a right partial body 18 of the base body 2, while the strip element 4 holds the left partial body 16 and the right partial body 18 together.

In the state shown in Figure 3, the left part body 16 and the right part body 18 can be pivoted about a (pivoting) axis D, which is located in the strip element 4. The strip element 4 is bendable, so that the pivotability of the parts bodies 16 and 18 is easily possible. The elasticity of the strip element 4 is low, so that the body parts 16 and 18 can only be moved relative to one another to a very small extent, be it at a small pivoting angle a, as shown in Figure 3, or at a larger pivoting angle a, which can be a maximum of about 180°. The special design of the strip element, in particular the above-mentioned small thickness, the woven structure and the bendability essentially resulting from this, with simultaneous low elasticity in relation to tensile stresses applied to the strip element, ensure that the parts bodies 16 and 18 can be pivoted precisely about the pivoting axis D.

The view of the right partial body 18 from Figure 3 shown in Figure 4 shows a separation surface 22 of the tooth model 6, a separation surface 24 of the base body 2 and a structured fracture surface 26 of the base body 2. The transition from the separation surface 24 to the structured fracture surface 26 runs along a circular path

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and results from the fact that the separation of the tooth model 6 and the base body 2 into two partial bodies 16 and 18 was carried out with a circular, rotating cutting disc. The cutting cut made with the cutting disc through the tooth model 6 and partially the base body 2 leads through one of the recesses 14, which is filled with plaster of the tooth model 6. The axis D runs horizontally in the illustration in Figure 4 and through the strip element 4, which acts like a hinge during pivoting, with the help of which the body parts 16 and 18 can be pivoted.

In a manner not shown, the base body 2 of the model carrier 1 can have a curved shape - in plan view - in order to be adapted to possibly curved rows of teeth.

The use of the model carrier 1 according to the invention when producing a dental model and when carrying out work on a dental model, for example when producing dental crowns, is described below with reference to Figures 1 to 4.

To produce a dental model, an impression of part of a set of teeth is taken in the usual way using an impression tray. The impression of the teeth, which is made in a special impression material, is then filled with modeling plaster to such an extent that a small mountain of plaster protrudes above the impression. The model carrier 1 according to the invention is pressed into this mountain of plaster with its top side 10, which has several depressions 14, so that modeling plaster flows into the depressions 14 and, after the modeling plaster has hardened, there is a firm connection between the dental model and the model carrier. After the plaster has hardened, the impression tray can be separated from the dental model and a dental model 6 is present, which is attached to the model carrier 1, as shown in Figure 1. The dental model is now ready for further use.

If the tooth model 6 attached to the model carrier 1 is to be used, for example, to be able to work on crowns to be inserted into the patient before insertion using the tooth model and to be able to fit them into the tooth model, it is desirable to separate individual teeth of the tooth model so that aproximal surfaces are more easily accessible. To do this, a cut is made through the tooth model 6 between two teeth and partially through the base body 2 of the model carrier 1, for example using a rotating, thin

cutting disc.

As can best be seen in Figure 4, the tooth model 6 is completely severed to form a separating surface 22 and the base body 2 is partially severed to form a separating surface 24 up to a circular line 30 shown in Figure 4. The partial severing of the base body 2 and the remaining connection over the non-severed area creates a predetermined breaking point in the base body 2 of the model carrier in this area. The base body 2 is now broken through by manually applying a bending moment to form structured breaking surfaces 26, 27 in the area of the predetermined breaking point, so that, as can be seen in Figure 3, a left partial body 6 and a right partial body 18 are created, the latter of which is also shown in Figure 4. After the base body 2 has been broken, the partial bodies 16 and 18 are only connected to one another via the strip element 4. They can be pivoted about the axis D. The angle σ shown in Figure 3 can take on values between 0 and 180°. The strip element 4 takes on the function of a hinge. In the pivoted state, the severed tooth models, especially their aproximal surfaces, are easily accessible.

Due to the material properties of the base body 2, it tends to brittle fracture and the fracture surfaces that arise when breaking through do not crumble and have a more or less randomly occurring structure. If the angle σ takes on the value 0 after breaking through and possibly processing the tooth models, the structured fracture surfaces 26 and 27 fit together almost seamlessly.

In the manner described above, several teeth of the dental model can be separated.

Claims (17)

•-•12·- Claims 1. Device {1) for carrying at least one tooth model (6) (model carrier) with a substantially rigid base body (2) which has a bottom side (8) and a top side (10) to which a tooth model (6) can be attached, characterized in that a flexible strip element (4) is permanently attached to the base body (2) along the underside (8) and the base body consists of a substantially brittle material such as plaster or the like, which can be broken essentially splinter-free to form structured fracture surfaces. 2. Model carrier according to claim 1, characterized in that the strip element (4) is thin in relation to the thickness of the base body (2) determined by the average distance between the underside (8) and the upper side (10). 3. Model carrier according to claim 1 and/or 2, characterized in that the underside (8) of the base body (2) is substantially flat and is completely covered by the strip element (4). 4. Model carrier according to at least one of the preceding claims,
characterized in that the strip element (4) is connected to the base body (2) by a positive connection. 5. Model carrier according to at least one of the preceding claims,
characterized in that the strip element (4) has a woven structure. 6. Model carrier according to at least one of the preceding claims,
characterized in that the strip element (4) has a plurality of curved, protruding clamp elements (12) which are clamped to the base body (2). 7. Model carrier according to claim 6, characterized in that the clamp elements (12) are hook-shaped. * Z via·: 8. Model carrier according to at least one of the preceding claims, characterized in that the strip element (4) is designed in the manner of a Velcro strip. 9. Model carrier according to at least one of the preceding claims, characterized in that the base body (2) is cuboid-shaped. 10. Model carrier according to at least one of the preceding claims, characterized in that the base body (2) has the shape of a curved cuboid. 11. Model carrier according to at least one of the preceding claims, characterized in that the base body (2) consists of plaster. 12. Model carrier according to at least one of the preceding claims, characterized in that the upper side (10) of the base body (2) is provided with several recesses (14). 13. Model carrier according to claim 12, characterized in that the recesses (14) are approximately hemispherical. 14. Model carrier according to claim 13, characterized in that the recesses (14) are approximately cylindrical. 15. Model carrier according to claim 13 or 14, characterized in that the recesses (14) have a diameter of approximately one to 4 mm. 16. Model carrier according to at least one of claims 12 to 15, characterized in that the recesses (14) are arranged in rows. 17. Model carrier according to at least one of the preceding claims, characterized in that the strip element (4) is glued to the base body (2).