A DENTAL COLORING STAMP AND A METHOD OF COLORING

Abstract

A dental coloring stamp has a transfer pad for transferring a dental coloring solution to a precursor of a dental restoration. The transfer pad is at least partially formed of an open-celled elastic sponge and has a free transfer surface. The cross-section of the transfer pad is greater than a circular area of 10 mm in diameter so that a side of a dental restoration precursor can be stamped and thus colored. The invention helps facilitating the coloring of dental restorations.

Claims

1. A dental coloring stamp, comprising a dental coloring solution and a transfer pad for transferring the dental coloring solution to a precursor of a dental restoration, the transfer pad being at least partially formed of an open-celled elastic sponge, the transfer pad having a thickness along a stamping dimension and a transfer surface which extends in dimensions essentially laterally to the stamping dimension, wherein the transfer pad in dimensions laterally to the stamping dimension is greater than a circular area of 10 mm in diameter, and wherein the dental coloring solution comprises a solution comprising a solvent, a coloring agent comprising metal ions selected from one or more of Fe, Cr, Ni, Tb, Er, Pr, Mn, and a fluorescing agent comprising ions of Bi.

2. The dental coloring stamp of claim 1, wherein the stamping surface has a convex dome-shape being defined by an outer cross-section with a minimum width in a plane laterally to the stamping dimension, a height along the stamping dimension between said plane and the dome apex, and a ratio between the height and the minimum width of less than 1:1, respectively.

3. The dental coloring stamp of claim 1, wherein the outer cross-section corresponds to an overall outer cross-section of the transfer pad.

4. The dental coloring stamp of claim 1, further comprising a housing having a body in which the transfer pad is fixed and a cover, wherein the cover and the body are shaped and sized for sealingly mating with one another.

5. The dental coloring stamp of claim 4, wherein the body comprises a reservoir for holding the dental coloring solution, the reservoir having an opening being closed by the transfer pad, wherein the transfer surface faces in a direction from the reservoir toward outside the opening.

6. The dental coloring stamp of claim 4, wherein the body forms a well having a bottom wall from which a circumferential side wall protrudes, the transfer pad at a surface opposite of the transfer surface being fixed at the bottom wall of the well.

7. A method of coloring a dental restoration, comprising: providing a precursor of a dental restoration, the dental restoration precursor having two opposite sides in each of three dimensions of a Cartesian coordinate system; providing a dental coloring stamp soaked with a dental coloring solution; and stamping at least 80% of the surface of one side of the dental restoration precursor and the dental coloring stamp at least one time onto each other; and firing the dental restoration precursor to form the dental restoration.

8. The method of claim 7, further comprising removing the dental restoration precursor and the dental coloring stamp from each other within a determined time-period of 3 seconds after stamping.

9. The method of claim 7, further comprising: providing a first dental coloring stamp soaked with a dental enamel coloring solution; providing a second dental coloring stamp soaked with a dental dentin coloring solution; stamping at least 80% of the surface of a first side of the dental restoration precursor and the first dental coloring stamp at least one time onto each other; and stamping at least 80% of the surface of an opposite second side of the dental restoration precursor and the second dental coloring stamp at least one time onto each other.

10. The method of claim 7, wherein the dental restoration precursor is a precursor of a dental crown or bridge.

11. The method of claim 7, wherein the side stamped corresponds to a precursor of the occlusal or incisal side of the dental restoration.

12. The method of claim 7, further comprising: performing the stamping based on observing a penetration depth of the dental restoration precursor to a pre-determined position at the dental restoration precursor; and optionally marking the pre-determined position at the dental restoration precursor prior to stamping.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0041] FIGS. 1A-1D are perspective views of a dental coloring stamp according to an embodiment of the invention;

[0042] FIGS. 2A-2F illustrate an embodiment of the method of the invention;

[0043] FIGS. 3A-3F illustrate a further embodiment of the method of the invention;

[0044] FIGS. 4A, 4B are cross-sectional views of a dental coloring stamp according to an embodiment of the invention;

[0045] FIGS. 5A, 5B are cross-sectional views of a dental coloring stamp according to a further embodiment of the invention; and

[0046] FIG. 6 illustrates in a top view an occlusal side of a dental restoration/dental restoration precursor.

DETAILED DESCRIPTION OF THE INVENTION

[0047] FIGS. 1A-1D illustrate the technical principle on which the invention is based. A dental restoration precursor 100 is provided made of a pre-sintered ceramic or glass-ceramic material. Further a dental coloring stamp 10 is provided. The coloring stamp 10 has a transfer pad 11. The transfer pad 11 is formed of an open-celled elastic sponge. Thus, the transfer pad is configured to dischargeably absorb a liquid. In the example the transfer pad 11 is soaked with the dental coloring solution. Further, the transfer pad 11 has a minimum thickness in a stamping dimension X so that it can conform to the shape of the dental restoration precursor 100, in the example to the occlusal or incisal surface of the dental restoration pre-cursor 100. The thickness of the transfer pad 11 is preferably further configured to provide a desired capacity for the coloring solution absorbable within the transfer pad 11. The transfer pad 11 further has an obtuse free transfer surface 12 which extends in dimensions essentially laterally to the stamping dimension X. The transfer surface 12 forms the portion of the transfer pad 11 which is intended for being brought into contact with the dental restoration precursor 100.

[0048] As illustrated in FIG. 1B the coloring is performed by stamping one side of the dental restoration precursor 100 and the dental coloring stamp 10 onto each other. Thereby the transfer pad 11 is compressed and coloring solution is discharged therefrom. The discharged coloring solution is soaked into the dental restoration precursor 100. This is due to the fact that the dental restoration precursor is made of open-celled or porous material. Due to capillary effects the coloring solution automatically permeates into the open-celled material the dental restoration precursor 100 is made of. The travel of the coloring solution into the material automatically stops dependent on the amount of coloring solution soaked into the material, and the amount of coloring solution soaked in the material can be controlled by the frequency and time period for which the dental restoration precursor 100 and the transfer pad 11 are stamped onto one another. In this way the dental restoration precursor 100 can be partially soaked with coloring solution in a controlled and reproducible manner. That partial coloring of the dental restoration precursor results in the dental restoration to exhibit a color gradient after sintering. It is noted that although it is referred to a color or color gradient of the dental restoration precursor, any color or color gradation may only become visible in its final optical appearance after sintering the dental restoration precursor.

[0049] Accordingly a dental restoration may be provided with a color gradation by stamping a essentially the full side of the dental restoration precursor, meaning by stamping more than 80% of the surface of that side at once. Therefore the transfer pad 11 in dimensions laterally to the stamping dimension X is greater than the side of the dental restoration precursor to be stamped. In particular the transfer pad 11 in dimensions laterally to the stamping dimension X is preferably greater than an area at the greatest cross-section of a human molar tooth in a plane parallel to the occlusal plane of that tooth. Further each lateral dimension of the transfer pad 11 may be selected about 1.2 to 1.5 greater than the corresponding dimension at the greatest cross-section of the human molar tooth. This is to account for the shrinkage factor between the dental restoration precursor and the finished dental restoration. Based on these considerations it has been found that the transfer pad 11 desirably has lateral dimensions that are greater than a circular area of 10 mm in diameter.

[0050] The intensity and/or structure of the color gradation may be controlled by the time of stamping the dental restoration precursor 100 and the number of repetitions of the stamping step. In particular, the time-period between the first contact of the coloring stamp 10 dental restoration precursor 100 (FIG. 1B) and the removal of the coloring stamp 10 from the dental restoration precursor 100 (FIG. 1C) typically impacts the amount of coloring solution being transferred from the transfer pad 11 to the dental restoration precursor 100. Such time-period is also referred to as “stamping time-period” herein. Further, the intensity and/or structure of the color gradation may be controlled by the penetration depth of the dental restoration precursor 100 into the transfer pad 11. In particular the dental restoration precursor 100 may be stamped multiple times at different penetration depths.

[0051] FIGS. 2A-2F illustrate the method of the invention in more detail. In one step as shown in FIG. 2A a precursor 100 of a dental restoration is provided. In the example a precursor of a dental crown is shown in a top view (on the left) onto the topside (or occlusal/incisal side) and a bottom view (on the right) onto the underside (or the substructure-facing side). A suitable substructure onto which the finished crown may be fixed may be a natural tooth stump, a dental abutment or dental implant. The crown in the example is made of a ceramic material, in particular of a pre-sintered open-celled zirconia material.

[0052] The dental restoration precursor 100 is stamped with the underside onto the dental coloring stamp 20 (shown in FIG. 2B) and removed from the dental coloring stamp 20 again. Although the underside of the dental crown forms a cavity the elastically deformable stamping pad 21 is configured to penetrate into the cavity so as to transfer coloring solution to the underside. The stamping step is repeated four times at a stamping time-period of 3 seconds per stamping. Thereby the stamping is repeated on the same side of the dental restoration precursor. In this step the dental restoration precursor is provided with a dentin color shade. Such dentin color shade is intended to resemble the dentin color shade of a natural tooth.

[0053] The combination of stamping the enamel color shade at one side of the precursor followed by stamping the dentin color shade at the opposite side of the dental restoration precursor (or vice versa) has been identified as an efficient way to mimic a transition (referred to as “dentin-enamel transition” herein) of the dentin/enamel colors similar to a natural tooth.

[0054] An advantage of the stamping procedure of the invention results from the fact that the penetration depth of the dental restoration precursor into the (elastically deformable) transfer pad can be easily controlled. For example a user may press the dental restoration precursor into the transfer pad to a desired depth by adapting finger pressure and visually observing the penetration depth. This procedure can be facilitated by a thin line drawn (for example with a pencil) on the restoration precursor prior to stamping. Thus the penetration depth of the dental restoration precursor into the transfer pad can be pre-determined to control the position of the dentin-enamel-transition.

[0055] FIG. 2C shows the dental restoration after stamping in a drying step. In this step the solvent of the coloring solution is substantially eliminated.

[0056] The dental restoration precursor 100 in a further step is stamped with the topside onto a dental coloring stamp 20′ (shown in FIG. 2D) and removed from the dental coloring stamp 20′ again. The stamping step is repeated two times at a stamping time-period of 3 seconds per stamping. In this step the dental restoration precursor is provided with an enamel color shade. Such enamel color shade is intended to resemble the enamel color shade of a natural tooth.

[0057] FIG. 2F shows the dental restoration precursor 100 in a drying step for removing the solvent of the coloring solution from the dental restoration precursor 100.

[0058] The order of the stamping steps using dentin and enamel color may be reversed relative to the previous description or repeated alternately, as appropriate.

[0059] In the example of FIGS. 2A-2F the dental coloring stamp 20/20′ is configured for standing, for example on table top and the dental restoration precursor 100 is moved relative to the dental coloring stamp 20/20′.

[0060] In a further example as illustrated in FIGS. 3A-3F a dental coloring stamp 30 is provided which is configured as a hand-held device. The dental coloring stamp in this example is moved and the dental restoration precursor 100 is supported on a table top.

[0061] In FIG. 3A the dental coloring stamp 30 is prepared for use. The dental coloring stamp 30 has a reservoir 33 holding a sufficient amount of coloring solution for coloring multiple dental restoration precursors. The dental coloring stamp 30 further has a transfer pad 31 which is uncovered by removing a cap 34 of the dental coloring stamp 30.

[0062] In FIG. 3B the dental coloring stamp 30 is pushed with the transfer pad 31 onto a surface so as to cause the transfer pad 31 to soak with coloring solution.

[0063] The dental coloring stamp 30 is then used to stamp a side of a dental restoration precursor 100 for a stamping time-period of 3 seconds and removed from the dental restoration precursor 100 as illustrated in FIGS. 3C through 3E.

[0064] FIG. 3F illustrates in cross-sections through the dental restoration precursor 30 that the coloring solution has penetrated into a portion 101 of the dental restoration 100.

[0065] FIGS. 4A, 4B show a dental coloring stamp 20 in more detail. The dental coloring stamp 20 has a bottom well 25 and a cover 24. A transfer pad 21 is attached, for example glued, to the bottom well 25. In the example the dental coloring stamp 20 is configured for single use with the transfer pad 21 being pre-soaked with a coloring solution of a certain color selected from a plurality of different colors. However, in another example the transfer pad 21 of the dental coloring stamp 20 may not contain any coloring solution. In such an example the coloring solution may be added just prior to use. The cover 24 is used to protect the transfer pad 21 from the environment, for example during transport of the device from the factory in which the dental coloring stamp 20 is manufactured to the user (for example in a dental lab). Further a dental coloring stamp 20 which is intended for multiple uses the cover 24 can be used to seal the transfer pad 21 soaked with coloring liquid until any next use.

[0066] FIG. 4B shows the dental coloring stamp 20 supported on a table top with the cover 24 removed from the bottom well 25, and a dental restoration precursor 100 positioned relative to the transfer pad 21.

[0067] FIGS. 5A, 5B show an alternative dental coloring stamp 30 in more detail. The dental coloring stamp 30 has a body 35 and a cover 36 which in combination form a housing. Further the body 35 forms a reservoir for the coloring solution. A transfer pad 31 is received in an opening 36 of the reservoir. In the example the dental coloring stamp 30 is configured for multiple use. Accordingly a sufficient quantity of coloring solution for coloring a plurality of dental restoration precursors is provided in the reservoir.

[0068] FIG. 5B shows the dental coloring stamp 30 in use with the cover 34 removed from the body 35. A dental restoration precursor 100 is positioned relative to the transfer pad 31.

Example

[0069] A sponge (open celled with average cell size of 505±158 μm) was mounted in a 35 mm×35 mm Polystyrene container and saturated with Lava Plus™ Enamel Liquid (Lot #548286, expiration date 2017-03). A second container was prepared by mounting a stub made from composite (Pattern Resin from GC Company) into the bottom of the container. The stub size was selected to be slightly smaller than the inside of an average size molar crown. A second sponge from the same sponge material was prepared by cutting a cavity into one side to allow fit over the stub mounted in the bottom of the container. The sponge was mounted in the container such that the stub was completely covered. The sponge was then saturated with Lava Plus™ Body Shade Liquid A2 (lot #504874, expiration date 2016-01).

[0070] A molar crown was milled from Lava Plus™ High Translucency Zirconia. The crown was removed from the mill blank by cutting the sprues with a dental handpiece. The residual sprue stumps on the crown surface were removed with a dental handpiece and smoothed with sandpaper. The milling dust was removed with a soft bristled brush and cleaned by gently blowing with an air nozzle.

[0071] The transition between enamel and body region was marked by drawing a slight pencil mark in the location where the enamel shade should border the body shade. The crown was then gently pressed into the sponge containing the Lava Plus™ Body Shade Liquid A2 up to the pencil mark and immediately released. This pressing process was repeated 4 times. Care was taken to ensure that the stub mounted beneath the sponge was centered inside the crown. After briefly letting the crown sit to soak up shading liquid from its surface, the crown was turned over, and gently pressed 2 times into the sponge containing the Lava Plus™ Enamel Liquid EL.

[0072] The crown was then placed into the Lava Therm™ and fired in the classical Lava Plus firing program and thus converted from its pre-sintered to its finally sintered stage.

[0073] The resulting molar crown displayed a natural gradient as expected for a natural-gradient-shading crown by painting shading liquid onto the crowns with a brush. The shading process was at least twice as fast as the natural-gradient-shading method.

[0074] In one trial which was conducted in accordance with the Example the time period required for providing a dental restoration precursor with a coloring solution for appropriately coloring a dental restoration finished from this dental restoration precursor was about 50 seconds as opposed to about 3 Minutes in a comparative trial in which a dental restoration precursor was provided with coloring solution by use of a brush.