METHOD FOR PRODUCEING A TOOTH RESTORATION WITH A TARGET COLOR VALUE, CORRESPONDING KIT AND USE OF A GLAZE IN THE METHOD.

Description

[0001] The present invention relates to a method according to claim 1 for producing a dental restoration, wherein the coloring is achieved by glazing a molded body with a colored glaze of a defined color value and heat-treating the glazed molded body. Also part of the invention are a kit according to claim 10 and the use of a glaze according to claim 14.

[0002] Restorative dentistry refers to the treatment of dental problems while simultaneously restoring the teeth both functionally and aesthetically. The primary focus is on replicating the natural appearance of the teeth, which in many cases determines the aesthetic acceptance of a dental restoration. For this purpose, a range of basic shades are typically available, which are then color-matched to the existing teeth.

[0003] Conventional tooth color determination is usually carried out using so-called color rings or scales, which are provided with color samples and serve for visual color matching, whereby the compilation of color samples traditionally corresponds to the most frequently occurring tooth colors in nature, which have been empirically determined.

[0004] In this context, DE 693 19 291 describes a color-mixing indicator device used in the selection of desired artificial tooth colors for the manufacture of bridges, crowns, partial dentures, and the like. A set of tooth color-mixing indicator devices is disclosed, each indicator device comprising a plurality of color samples arranged in an array around a central pattern of color samples, each sample being spaced apart from these neighboring samples. The colors of the samples represent colors of a predetermined color system having a three-dimensional coordinate system (L, a, b) weighted by the aforementioned array, with the color of each sample corresponding to the color at the corresponding position in the coordinate system (L, a, b).wherein the colors of the patterns of each participating device lie in a plane of the coordinate system and the plane corresponding to each device is arranged substantially parallel to and at a distance from the planes of the other participating devices, and wherein in the use of the set a patient's tooth can be compared with any of the participating devices and a desired tooth color can be mixed for production from a selected pair of color patterns by forming a mixture of the color materials used to produce the selected pair, wherein the central color patterns of mutually adjacent planes are arranged along a common line and offset with respect to an axis (L) of the coordinate system that is perpendicular to mutually adjacent planes.

[0005] Using such color scales, the basic tooth color is determined step by step according to the three color dimensions of brightness, color intensity, and hue, which determine human color perception. Corresponding color scales are commercially available, for example, under the name VITA SYSTEM 3D-MASTER® (see Figure 2).

[0006] To achieve a more objective assessment of tooth color, the state of the art proposes a number of technically supported methods.

[0007] EP 3 643 272 describes a method for determining the color of a filling or other restoration, which is produced in particular using composite materials, wherein at least one tooth is electronically recorded, in particular scanned, with regard to its color value, wherein natural teeth are spectrally measured beforehand, wherein the measured color values ​​in a color space are divided into several, in particular four, categories, each forming a three-dimensional color cloud in the color space, by means of a structure-recognizing algorithm, and wherein the color of the filling is determined by determining to which of the categories the tooth has the smallest color difference or into which color cloud the tooth falls.

[0008] WO 2020 / 156855 discloses a support system for dental treatment, in particular by changing tooth color, comprising a measuring device which determines the dental data of teeth to be treated, in particular the tooth color and tooth coordinates, a data processing device and a camera for recording a tooth image, wherein the data processing device preferably has a receiving module and the measuring device a transmitting module for transmitting measured dental data from the measuring device to the data processing device, an assignment module integrated into the data processing device for assigning the received dental data to a tooth image, a selection device for selecting a degree of color change and an adjustment device for adapting the tooth image to the selected degree of color change.

[0009] EP 3 650 821 relates to a system for determining tooth color, comprising a 2D or 3D camera, wherein the system is adapted to capture images taken by the camera, and an attachment, wherein the attachment comprises a spacer having a connection device for attaching the attachment to the camera, wherein the spacer comprises an aperture by means of which the camera is adapted to capture an image of teeth, wherein the spacer is adapted to create a distance between a recording device of the camera and the tooth surface, and wherein the spacer is adapted to create a distance between the recording device of the camera and the aperture, wherein the camera has a normal recording mode without the use of the attachment and a color measurement mode for use with an attachment for measuring the color of the tooth.wherein the system for detecting the presence of the attachment on the camera is adapted based on changes in the image field captured by the camera in order to switch to a color measurement mode when these changes are detected in the image field.

[0010] WO 2020 / 154450 describes a method for color matching that includes the following steps: providing tooth measurement data, wherein the tooth measurement data includes at least one area of ​​application in which the dental restoration is to be used; providing restoration data; providing information on staining and glaze colors; generating a color characteristic from the tooth measurement data or other information, taking into account the restoration data, and calculating a multi-colored target color from the color characteristic, taking into account information on staining or glaze colors, and outputting the multi-colored target color for color matching of the dental restoration.

[0011] DE 10 2015 204 109 describes a sprayable veneering ceramic composition for dental restorations made of zirconium dioxide, comprising a dispersed phase and a dispersion medium, wherein the dispersed phase is a powdered glass ceramic comprising SiO₂, Nb₂O₅, Al₂O₃, Li₂O, Na₂O, and ZrO₂, and the dispersion medium contains isopropanol and / or ethanol and / or ethylene glycol, and wherein the sprayable veneering ceramic composition contains at least one blowing agent. To optimize the aesthetics of the veneering ceramic, the powdered glass ceramic may contain pigments as coloring or fluorescent additives.

[0012] US 2021 / 0322283 discloses a glaze composition for zirconia dental restorations. The glaze composition comprises a liquid, glass particles, and hydrophilic silica nanoparticles.

[0013] US 4,828,117 describes a multi-layered dental restoration with a translucent porcelain layer covering a more opaque ceramic layer, with the color of the two layers being matched.

[0014] CN 108784875 relates to a color chart sample made of zirconium oxide.

[0015] WO 2020 / 185086 refers to a procedure intended to give a dental restoration a natural color and optical depth, whereby the color and optical properties are based on those of a neighboring or adjacent tooth.

[0016] US 5,906,490 provides a kit and a process for the manufacture of dental products, in which three materials with different brightness values ​​are formed into layers of increasing opacity.

[0017] Both conventional, subjective-visual tooth color assessment and technically supported, objective tooth color measurement are influenced by numerous factors, meaning the aesthetic result often depends on the skill and experience of the dentist and dental technician. Furthermore, the existing system has the disadvantage of requiring a large number of samples to achieve the most accurate color match possible. In cases where an incorrect choice is made, time-consuming color adjustments and corrections are also necessary.

[0018] Therefore, there remains a need for a simplified and reliable system for selecting and manufacturing dental restorations with a natural aesthetic that blend seamlessly into the existing dentition. Furthermore, the ability to easily adjust tooth color is desirable.

[0019] Against this background, the present invention provides a method for producing a dental restoration that allows for simple and efficient color matching and significantly reduces the number of samples that need to be kept for accurate color matching.

[0020] A first object of the present invention is therefore a method for producing a dental restoration, comprising the following steps: a) Providing a mold for dental restorations, wherein the mold has a base color value FW(F) and wherein the base color value FW(F) of the mold has a maximum difference value AE of 5 with respect to a target color value FW(Z) of the dental restoration; b) Applying a glaze to the mold, wherein the glaze has a defined color value FW(Gx); c) Heat-treating the glazed mold while preserving the dental restoration. characterized in that the defined colour value FW(Gx) of the glaze corresponds to the difference AE between the colour values ​​FW(Z) and FW(F), wherein the colour values ​​are CIEL*a*b* values ​​and the glaze is applied to the molded body in a thickness of 10 to 50 µm, preferably 20 to 40 µm.

[0021] The color values ​​and difference values ​​are CIEL*a*b* values, with the difference preferably relating to one of the values. The determination of such values ​​is known to those skilled in the art and is described, for example, by A. Baltzer and V. Kaufmann-Jinoian in "The Determination of Tooth Colors," published in QZ Quintessence Dental Technology, 30th year, July 2004.

[0022] While conventional methods for manufacturing dental restorations rely on the experience of the dental technician and the color matching of the restoration is usually performed manually, the method according to the invention uses a targeted selection of glazes with a defined color value that corresponds to the difference between the base color value and the target color value of the restoration, thus eliminating the empirical approach underlying the conventional method. Instead, a targeted adjustment of the restoration is made possible by the targeted selection of a glaze with a suitable color. Therefore, in a preferred embodiment, the glaze with the defined color value FW(G x ) is provided by selecting from a range of glazes with defined color values ​​FW(G).

[0023] The glaze is preferably selected such that its color value FW(Gx) corresponds to the difference between the base color value FW(F) of the molded body and the target color value FW(Z) of the molded body. Therefore, for example: FW Z 1 = FW F 1 + FW G 1

[0024] In other words: FW G x = FW Z y − FW F z mit y = x + z und y − z < 5

[0025] In cases where a suitable tooth shade is unavailable or the user has made an incorrect selection, manual color correction is often necessary. This requires first applying the correct ceramic stain to the correct area with a brush or spray, which demands a certain level of experience. This is followed by a so-called stain-fixing firing. Subsequently, a glaze is applied and a glaze firing is performed; only then can the final color effect be definitively assessed. The inventive method allows for color matching in a single firing, thus enabling a faster evaluation of the result.

[0026] Unlike conventional veneers, which are generally colorless and used to achieve a specific gloss, the inventive method uses colored glazes, the coloring preferably being achieved by colored pigments. In a preferred embodiment of the inventive method, glazes are therefore used that comprise a liquid mixing phase and a solid phase comprising coloring substances, preferably colored pigments, wherein the proportion of the liquid mixing phase in the glaze is at least 60% by weight, based on the total weight of the glaze.

[0027] In this way, a selection of glazes with defined color values ​​can be provided, from which the glaze is chosen whose color value corresponds to the difference between the base color of the molded part and the target color value to be achieved. This eliminates the step of empirically mixing the glaze, and the target color value is achieved by applying only one glaze.

[0028] In the inventive method, the provision of the preform is preferably achieved by selecting from a set of preforms, each with a defined base shade value FW(F), by comparison with the teeth adjacent to the restoration in the patient's mouth, preferably using a shade guide for tooth shade determination. This method of provision, combined with color adjustment by applying a selected glaze, makes it possible to maintain a limited selection of different base shades, the color of which can be adjusted by a corresponding glaze. The need to maintain a complete assortment of preforms is thus eliminated. Instead, it is now possible to achieve specific shades from defined starting points using different colored glazes.Therefore, the base color value and the target color value are preferably defined color values ​​as specified in a standardized color scale for tooth color determination. Such standardized color scales are known to those skilled in the art and are commercially available, for example, under the names VITA classical A1-D4 ®<, VITA SYSTEM 3D-MASTER ®< or VITA Toothguide 3D-MASTER ®< (see also Figure 2).

[0029] To minimize the influence of subjective color perception on color selection, it has proven advantageous to use digital support. Therefore, an embodiment of the method according to the invention is preferred in which the determination of ΔE and / or the selection of the shaped body is computer-aided.

[0030] According to the inventive method, the target color value FW(Z) of the dental restoration is achieved by applying a corresponding glaze. It has proven advantageous to limit the thickness of the glaze application in order to minimize any impairment of the color result.

[0031] According to the invention, the glaze is therefore applied to the molded body in a thickness of 10 to 50 µm, preferably 20 to 40 µm. The application of the glaze can be carried out manually or mechanically using methods known to those skilled in the art.

[0032] The inventive method uses glazes with defined color values ​​to achieve color matching of a provided molded body. A further object of the present invention is therefore a glaze for use in the inventive method, wherein the glaze i) a liquid mixing phase; and ii) a solid phase comprising coloring substances, preferably colored pigments, exhibits, wherein the proportion of the liquid mixing phase in the glaze is at least 60 wt.%, based on the total weight of the glaze, and wherein the glaze has a defined colour value FW(G x ) exhibits.

[0033] The defined colour value FW(G x ) of the glaze corresponds to the difference ΔE between the basic colour value FW(F) of a molded body and the target colour value FW(Z) of a dental restoration to be produced from this molded body.

[0034] The mixing phase is preferably selected from the group consisting of water, one or more alcohols, and mixtures thereof. The alcohol is preferably selected from the group consisting of monohydric, dihydric, and trihydric alcohols, as well as mixtures thereof. In a particularly preferred embodiment, the alcohol is selected from the group consisting of glycerol, 1,3-butanediol, 1,2-propanediol, ethanol, and mixtures thereof.

[0035] In a preferred embodiment, the mixing phase further comprises one or more complexing agents, preferably selected from the group consisting of ethylenediaminetetraacetic acid and citric acid.

[0036] Commercially available mixing solutions, such as Triplex® Solution B, can be used.

[0037] The solid phase of the glaze can be composed of materials known in the prior art. Preferably, the glaze uses a base mixture as the solid phase, to which coloring substances, in particular colored pigments, are added as required. In a preferred embodiment, the solid phase of the glaze comprises 45 to 70 wt.% SiO₂, particularly preferably 50 to 65 wt.%, based on the total weight of the solid phase. A further preferred embodiment is one in which the solid phase comprises one or more of the following components, each based on the total weight of the solid phase: 5 to 15 wt.%, preferably 7 to 13 wt.% Al 2 O 3 ; 5 to 15 wt.%, preferably 7 to 13 wt.% B 2 O 3 ; 5 to 15 wt.%, preferably 7 to 13 wt.% K 2 O ; 5 to 15 wt.%, preferably 7 to 13 wt.% Na 2 O .

[0038] To achieve the desired color values, the solid phase can contain up to 5 wt% of coloring substances, especially colored pigments, based on the total weight of the solid phase.

[0039] The coloring substances used can be pigments and pigment mixtures commonly employed in the industry, such as those used in the ceramics, glass, and porcelain industries. Therefore, the glaze according to the invention exhibits a high degree of compatibility with existing systems.

[0040] In a further preferred embodiment, the glaze is preferably supplied as a kit, comprising a container with the mixing phase and a container with the solid phase comprising coloring substances. This form of supply offers the advantage that the desired glaze can be mixed on site and drying out during storage is prevented.

[0041] The present invention aims to facilitate the fabrication of dental restorations with desired color values. In this context, a further aspect of the present invention comprises a kit for the fabrication of a dental restoration. a) a range of glazes for molded bodies for dental restorations, wherein each glaze has a defined colour value FW(G x ) where the colour values ​​FW (G x ) correspond to the differences ΔE between the colour samples of a standardised colour scale for tooth colour determination and where ΔE is not greater than 5, and b) a colour guide for matching a determined ΔE value to the corresponding glaze.

[0042] The kit according to the invention is preferably used in the method according to the invention and allows a dental restoration with a target shade FW(Z) to be achieved simply and with only one heat treatment, starting from a mold body with a base shade value FW(F), by selecting a suitable glaze, wherein the shade value FW(G) of the glaze corresponds to the difference ΔE between the base shade value FW(F) of the mold body and the target shade value FW(Z) of the dental restoration. The kit according to the invention enables the targeted selection of the suitable glaze, which corresponds to the determined shade value difference ΔE between the base shade value FW(F) and the target shade value FW(Z), by providing a shade guide. By applying the glaze and heat-treating, the shade difference can thus be compensated for, and a dental restoration can be provided that blends aesthetically into the patient's existing dentition.

[0043] A number of standardized shade guides are available to those skilled in the art for determining tooth shade. Preferably, the standardized shade guide that may be part of the kit according to the invention is VITA classical A1-D4 ®< , VITA SYSTEM 3D-MASTER ®< or VITA Toothguide 3D-MASTER ®< .

[0044] In a preferred embodiment, the kit according to the invention further comprises a standardized color scale for determining tooth color.

[0045] The kit according to the invention makes it possible to achieve a broad color spectrum using a limited number of glazes. In a preferred embodiment, the kit comprises an assortment of 2 or more, preferably 3 or more, particularly preferably 4 or more glazes and / or not more than 10, preferably not more than 8, particularly preferably not more than 6 glazes.

[0046] In a further preferred embodiment, the kit also includes an applicator for applying the glaze to a mold for dental restorations. In another preferred embodiment, the kit according to the invention, in addition to the assortment of glazes, the shade guide, and optionally the applicator, further includes an assortment of molds for dental restorations, each with a basic shade value FW(F x), which preferably corresponds to the shade values ​​of a standardized shade guide for tooth shade determination. In this way, a complete package can be provided that allows for the simple and efficient fabrication of dental restorations.

[0047] Preferably, the glazes of the kit according to the invention are those according to the present invention.

[0048] Another object of the present invention is the use of a glaze with a defined color value FW(G x ) in the manufacture of dental restorations, wherein the color value FW(G x ) corresponds to the difference ΔE between the color samples of a standardized color scale for determining tooth color, wherein ΔE is not greater than 5.

[0049] Figure 1 and the following example illustrate the present invention, but are by no means to be understood as a limitation of the inventive concept.

[0050] Figure 1 illustrates the concept according to the invention, in which, starting from a dental restoration such as those commercially available, with a specific shade value FW(F x ), this shade value can be adjusted to a desired target shade value FW(Z x ). The target shade value is determined in particular by comparison with the existing dental situation of a patient and takes into account the individual tooth coloration of the patient. A colored glaze is therefore applied to the initial restoration, the shade value of which FW(G x ) corresponds to the difference between the shade value FW(F x ) of the initial restoration and the desired target shade value FW(Z x ).

[0051] Figure 2 shows a typical color scale for determining and selecting dental shapes (VITA Toothguide 3D-MASTER ®< )

[0052] Starting with a ceramic restoration with a base color value, for example FW(F1), the present invention enables simple and efficient color matching to a target color value FW(Z1) by applying a glaze whose color value FW(G1) corresponds to the difference between the color values ​​FW(F1) and FW(Z1). Depending on the requirements, this can be done in one or more stages. Suitable glazes are selected based on a recognized color scale, taking into account the hue and color intensity.

[0053] The starting material is a crown with a shade value FW (F 2), corresponding to shade 3M2 from the VITA SYSTEM 3D-MASTER ®< shade guide. This starting material is to be color-matched to the target shade FW (Z 5 ) (see Figure 1), which in this example corresponds to tooth shade 3M3 from the VITA SYSTEM 3D-MASTER ®< shade guide. To achieve this, a colored glaze is selected and applied, the shade value of which, at an application thickness of approximately 30 µm, corresponds to the difference between the starting shade value and the target shade value. Table 1 illustrates the procedure according to the invention: Table 1 product Color value Transmission [%] L* a* b* ΔE* ΔL Δa Δb Starting crown FW(2) 76,30 3,36 20,24 colored glaze * FW(G5) 43,31 74,43 3,33 23,76 Target color location FW(Z5, should) 76,40 3,80 22,50 2,27 -0,10 -0,17 -2,26 Crown + Glaze FW(Z5, is) 76,48 3,70 21,88 0,63 0,08 -0,10 -0,62 * Color was measured in transmission because it is a translucent glaze.

[0054] Due to the higher opacity, the color values ​​of the crowns are measurements in reflection.

[0055] As can be seen from the values ​​in Table 1, applying the colored glaze to the base crown achieves a good match with the desired target color value.

Claims

1. A process for producing a dental restoration, comprising the following steps: a) providing a molded part for dental restorations, wherein said molded part has a basic color value FW(F), and wherein said color value FW(F) of the molded part has a maximum difference value ΔE of 5 from a target color value FW(Z) of the dental restoration; b) applying a glaze to the molded part, wherein said glaze has a defined color value FW(Gx); c) heat-treating said glazed molded part to obtain the dental restoration, characterized in that the defined color value FW(Gx) of the glaze corresponds to the difference AE between the color values FW(Z) and FW(F), wherein said color values being CIEL*a*b* values and the glaze is applied to the molded part in a thickness of from 10 to 50 pm, preferably from 20 to 40 pm.

2. The process according to claim 1, characterized in that the glaze is provided with a defined color value by selecting from a number of glazes having defined color values FW(G).

3. The process according to at least one of claims 1 or 2, characterized in that the molded part is provided by selecting from a set of molded parts each having defined basic color values FW(F) by comparing with the teeth neighboring the restoration in the patient's mouth by using a color scale.

4. The process according to at least one of the preceding claims, characterized in that the basic color values are those that correspond to the color values in the standardized color scales for tooth color determination.

5. The process according to at least one of the preceding claims, characterized in that the determination of the AE and / or the selection of the molded part is effected with computer assistance.

6. The process according to at least one of the preceding claims, characterized in that a glaze is used that i) has a liquid mixing phase and ii) a solid phase including coloring substances, wherein the proportion of the liquid mixing phase in the glaze is at least 60% by weight, based on the total weight of the glaze, and wherein said glaze has a defined color value FW(Gx).

7. The process according to at least one of the preceding claims, characterized in that the liquid mixing phase i) of the glaze is selected from the group consisting of water, one or more alcohols, and mixtures thereof, in which said alcohol is preferably selected from the group of monohydric, dihydric and trihydric alcohols, and mixtures thereof, especially from the group consisting of glycerol, 1,3-butanediol, 1,2-propanediol, ethanol, and mixtures thereof.

8. The process according to at least one of the preceding claims, characterized in that the liquid mixing phase i) of the glaze further includes one or more complexing agents, preferably selected from the group consisting of ethylenediaminetetra-acetic acid, and citric acid.

9. The process according to at least one of the preceding claims, characterized in that said glaze is in the form of a kit, said kit comprising a first container including the liquid mixing phase, and a second container including the solid phase with coloring substances.

10. A kit for performing a process for producing a dental restoration according to at least one of the preceding claims, including a) an assortment of glazes for molded parts for dental restorations, wherein each glaze has a defined color value F(Gx), in which the color values F(Gx) correspond to the differences AE between the color samples of a standardized color scale for tooth color determination, and in which AE is not higher than 5; and b) a color guide for assigning an established AE value to the corresponding glaze.

11. The kit according to claim 10, characterized in that said assortment includes 2 or more, preferably 3 oder more, more preferably 4 or more, glazes and / or not more than 10, preferably not more than 8, more preferably not more than 6, glazes.

12. The kit according to at least one of claims 10 or 11, characterized in that the kit further includes an applicator for applying the glaze to a molded part for dental restorations.

13. The kit according to at least one of claims 10 to 12, characterized in that said glazes are glazes according to at least one of claims 6 to 9.

14. Use of a glaze with a defined color value FW(Gx) in a process for producing dental restorations according to any of the preceding process claims, in which the color value FW(GX) corresponds to the difference AE between the color samples of a standardized color scale for tooth color determination, and in which AE is not higher than 5.