Abstract:
A method of making a customized dental blank. The method has steps of obtaining from a dental practitioner a first color scheme and a different second color scheme as well as a first dimensional information for the first color scheme and a different second dimensional information for the second color scheme. The first and second dimensional information each relate to a size and/or a location within dimensions of the dental blank. The method further has the step of manufacturing the customized dental blank which has a first portion based on the first dimensional information according to the first color scheme and a second portion based on the second dimensional information according to the second color. Further the method has the step of providing the dental practitioner with the customized dental blank. The method helps facilitating the making of a dental restoration from a blank.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a method of making a customized dental blank, in particular a dental blank having a first portion based on first dimensional information according to a first color scheme and a second portion based on second dimensional information according to a second color scheme. 
       BACKGROUND ART 
       [0002]    The preparation of dental restorations often includes milling or grinding the restoration from a dental blank that has a standardized size and shape. Such blanks are typically available in different tooth colors and may be selected in accordance with a particular tooth color of a patient&#39;s teeth. 
         [0003]    Typically a dentist prepares a tooth to be restored in a patient&#39;s mouth, sends a dental impression from the patient&#39;s dentition along with tooth color information to a dental lab and obtains the finished dental restoration from the dental lab. The dental lab typically holds a stock of dental blanks from which an appropriate blank is selected for making the dental restoration. The size of the stock and the selection is always a compromise. On the one hand the stock size is desirably small but large enough to have an appropriate blank for many different dental restorations available. On the other hand the selection should be such that tolerances, in particular regarding the color, between the blank and the tooth color information obtained from the dentist are accepted but kept within limits. The making of dental restorations having rare colors or color compositions thus is particularly difficult to address and may require either a relatively large stock or the acceptance of large tolerances. 
         [0004]    There are further approaches for providing individualized dental blanks WO 2013/122662 for example discloses a dental milling block comprising a dental article having an outer surface, the dental article having been produced based on personalized data, wherein the outer surface of the dental article is at least partially covered with a surrounding material. 
         [0005]    The invention further relates to a process of producing a dental milling block, the process comprising the steps of: a) providing a personalized Data Set C containing geometry data of the dental article and color data related to said geometry data, b) generating a layer of hardenable material on a surface, c) applying a color agent to the layer of hardenable material of step b), wherein the color agent is applied to at least some regions of those areas of the layer of hardenable material which are related to the geometry data of the dental article, d) consolidating the result obtained in step c) thereby obtaining an at least partially hardened layer of material. 
         [0006]    Although the current approaches for manufacturing of dental restorations may provide a variety of advantages, there is still a desire for a method of manufacturing dental restorations in a cost efficient manner and at a good aesthetic quality. 
       SUMMARY OF THE INVENTION 
       [0007]    The invention relates to a method of making a customized dental blank. The method comprises the steps of:
       obtaining from a dental practitioner a first color scheme and a different second color scheme as well as a first dimensional information for the first color scheme and a different second dimensional information for the second color scheme, wherein the first and second dimensional information each relate to a size and/or a location within dimensions of the dental blank;   manufacturing the customized dental blank having a first portion based on the first dimensional information according to the first color scheme and a second portion based on the second dimensional information according to the second color scheme; and   providing the dental practitioner with the customized dental blank.       
 
         [0011]    The invention is advantageous in that it provides dental blanks from which two or more differently colored dental restorations are obtainable. This allows for example to provide a plurality of differently colored blank portions in one blank. Even not making use of all blank portions such blank may be less expensive and space consuming than a number of individual blanks providing the same amount of colors. 
         [0012]    A dental practitioner for the purpose of the present invention may be a dentist, a dental technician of a dental assistant, for example. The dental practitioner may perform the determination of the first and second color scheme by use of a shade guide. In particular the dental practitioner may visually compare the shade guide having several different color samples with a tooth adjacent or opposite a tooth to be restored. The dental practitioner may determine the first color scheme according to a color sample which matches one portion of the tooth best and the second color scheme according to a different color sample which matches another portion of the same tooth best. Further, the dental practitioner may visually compare the shade guide with a first tooth and a second tooth in a patient&#39;s mouth. The dental practitioner may determine the first color scheme according to a color sample which matches the first tooth best and the second color scheme according to a different color sample which matches the second tooth best. 
         [0013]    In one embodiment at least one of the first and second color scheme comprises a color gradient or consists of a single color. Accordingly a color scheme as referred to in this specification may be a single color only or a gradient formed of multiple colors. In an embodiment the method further comprises the step of obtaining first dimensions of the first portion and second dimensions of the second portion from the dental practitioner. The method may further comprise the step of obtaining material information from the dental practitioner. The material information preferably relates to a material the dental blank is made of The material may be selected from among a ceramic, a glass ceramic or a composite material, in particular selected from among zirconia, alumina, lithium disilicate, resin nano ceramic, and hybrid materials. Accordingly appropriate information for making a blank which is customized regarding the color configuration and the material may be obtained from the dental practitioner. 
         [0014]    In one embodiment the method comprises the step of obtaining from a plurality of dental practitioners first color schemes and different second color schemes and corresponding first dimensional information and second dimensional information. Accordingly different customized dental blanks can be provided to different dental practitioners. 
         [0015]    In a further embodiment the method comprises the step of providing a dental blank-configurator allowing at least the selection of the first and second color scheme from a plurality of pre-defined color schemes. Such dental blank-configurator may be computer-based, for example provided via the Internet. The blank-configurator may be configured to display an assortment of different blank types. Such different blank types may comprise blanks of a different three-dimensional size and/or shape, for example. Further the blank-configurator may be configured to display a variety of different tooth colors. The blank-configurator may be configured such that a user of the configurator can select the blank from the displayed blank types and at least two colors associated with the selected blank. The blank-configurator may be further configured to accept user input regarding the first and second dimensional information. Dimensional information may comprise information about the size, shape and/or location of a portion within the blank which is associated with the first, second or further color scheme. The blank-configurator may be adapted such hat a configuration entered by the dental practitioner can be sent to the blank manufacturer, for example via the Internet. 
         [0016]    In a further embodiment the method further comprises the steps of:
       assigning the customized dental blank an individual code based on at least the first and second color scheme and the first and second dimensional information;   providing the customized dental blank with the individual code in a machine readable form; and   controlling machining of the blank using machining instructions that are based on the individual code.       
 
         [0020]    In this embodiment the individual code preferably comprises at least the first and second dimensional information. The machine used for machining the blank is preferably adapted to read the individual code, to decode the individual code and to control the machining in accordance with the first and second dimensional information. For example the individual code may be stored in a memory of an integrated circuit attached to the dental blank and the machine may have an electronic reader to read that memory. In one example an RFID tag may be used to store the individual code and an RFID reader of the machine may be configured to read the RFID tag. The individual code may comprise all information necessary to machine the dental restoration except for the data relating to the individual shape of the dental restoration. The skilled person will recognize other possibilities of providing the dental blank with the individual code. For example a bar code, OCR letters or magnetic storage media may be used. 
         [0021]    In a further embodiment the first portion and the second portion are spaced from each other with a third portion extending between the first portion and the second portion. Further at least one of the first and second portion is/are shaped based on a dental arc or partial dental arc. Thus a variety of differently configured dental blanks can be made available. 
         [0022]    In a further aspect the invention relates to a method of making a dental restoration. The method comprises the steps of:
       providing a customized dental blank according to the invention;   capturing at least one natural tooth color from a patient&#39;s dentition; and   determining the first and/or second color scheme based on the at least one natural tooth color.       
 
         [0026]    The natural tooth color may be captured directly, for example using a color measuring device, or indirectly, for example by matching using a tooth color shade guide. 
         [0027]    In one embodiment the method further comprises the steps of:
       capturing the shape of at least part of the patient&#39;s dentition;   designing a dental restoration based on the captured shape; and   machining the dental restoration.
 
For capturing the shape of at least part of the patient&#39;s dentition an intra-oral scanner may be used. Such a scanner may be configured to measure the natural tooth color of the patient&#39;s teeth. Alternatively a separate color measuring device may be used. The design of the dental restoration id preferably preformed using a CAD system that is configured to provide a computer representation of the dental restoration in the form of data to an automated manufacturing system. The automated manufacturing system, for example a CNC milling or grinding machine, is preferably configured to automatically machine the dental restoration based on the computer representation in data form.
       
 
         [0031]    The invention further relates to a system for making a customized dental blank. The system comprises:
       a scanner for capturing the shape of at least part of the patient&#39;s dentition;   a computer being configured to receive input about a natural tooth color associated to the patient&#39;s dentition;   software configured to receive a first color scheme and a different second color scheme based on the natural tooth color;   the software being further configured to receive a first dimensional information for the first color scheme and a different second dimensional information for the second color scheme within dimensions of the dental blank;   the software being further configured to initiate, by data transfer, an order of the customized dental blank based on the first and second color scheme and the first and second dimensional information.       
 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0037]      FIG. 1  is a diagram illustrating an embodiment of the method of the invention; 
           [0038]      FIG. 2  is a diagram illustrating a further embodiment of the method of the invention; 
           [0039]      FIG. 3  is a perspective transparent view of a blank obtainable from the method in an embodiment of the invention; and 
           [0040]      FIG. 4  is a transparent top view of a further blank obtainable from the method in an embodiment of the invention; and 
           [0041]      FIGS. 5-7  are perspective transparent views of still further blanks obtainable from the method in an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0042]      FIG. 1  illustrates an exemplary method  10  according to the invention. The method  10  generally allows a dental practitioner to obtain an individually colored dental blank from a blank manufacturer. The individual colors of the blank may for example be associated to two or more dental restorations for a single patient or to two or more dental restorations of multiple patients. In this regard a dental restoration may be a dental crown and/or dental bridge which can be machined (for example milled or ground) from the individual blank. The individual colors of the blank colors may be determined as follows. 
         [0043]    In a step  11  a first color scheme and a different second color scheme are determined. In particular a dental practitioner may determine one or more tooth colors of one or more teeth in a patient&#39;s mouth. For example a patient may have a tooth to be restored and the dental practitioner may determine the color of that tooth and/or the color of a tooth neighboring the tooth to be restored. The dental practitioner may perform the determination of the one or more tooth colors by use of a shade guide. Such a shade guide is for example available under the designation VITA classical A1-D4 Shade Guide from VITA Zahnfabrik, Germany. Alternatively or additionally the dental practitioner may perform the determination of the one or more tooth colors by use of color measuring device. Such a color measuring device is for example available under the designation VITA Easyshade® Advance 4.0. The shade guide or color measuring device typically provides the tooth color in the form of a color code, for example A1, A2, A3 . . . D4. If a shade guide is used color samples of the shade guide may be compared with a color of a natural tooth in the patient&#39;s mouth and the color code of the color sample which matches the color of the natural tooth best is the color code provided via the shade guide. The color measuring device may in contrast display the color code corresponding to a natural tooth color measured by the device. 
         [0044]    The dental practitioner may directly use two colors determined in a patient&#39;s mouth as the first and second color scheme. However the dental practitioner may further select a different color based on the determined color and use the selected color as the first and/or second color scheme. The dental practitioner may for example select the next brighter or darker color code of the color code determined in the patient&#39;s mouth. 
         [0045]    In one example the dental practitioner determines a first tooth color of a tooth in a first patient&#39;s mouth and a different second tooth color of a tooth in a second patient&#39;s mouth wherein the dental practitioner uses the first tooth color as the first color scheme and the second tooth color as the second color scheme. In this example the first and second color scheme each are formed by a single color only. The dental practitioner may however in another example determine a color gradient based on one or more tooth colors of a tooth in a patient&#39;s mouth. This color gradient (or two different color gradients) may then be used as the first or second color scheme (or as the first and second color scheme, respectively). For example based on a determined natural tooth color A2 the dental practitioner may determine a color gradient from A2 to A3. This may provide a color shading which relatively pleasantly resembles a natural tooth. 
         [0046]    Once the dental practitioner has determined the first and second color scheme (and eventually further color schemes) the dental practitioner in step  12  further determines a first dimensional information for the first color scheme and a different second dimensional information for the second color scheme. For example if a patient is intended to be provided with a dental crown the dental practitioner may assign the first color scheme a three-dimensional size of for example 12 mm×12 mm×12 mm of a cube shape. Other sizes are possible as appropriate. Further if that patient or a further patient is intended to be provided with a dental bridge the dental practitioner may assign the second color scheme a three-dimensional size of for example 12 mm×12 mm×24 mm of a cuboid shape. Other sizes and shape are possible. For example for larger dental bridges a three-dimensional shape corresponding to an arch extending at a certain cross-section may be used. It is noted that the step of determining the first and second color scheme and the step of determining the first and second dimensional information, respectively, are exchangeable in the order in which they are performed. 
         [0047]    The dental practitioner may further assign the first and second color scheme a particular location in a blank. The dental practitioner may for example be provided with one or more three-dimensional standard shapes of blanks Based on those the dental practitioner may determine a first particular location for the first color scheme and a different second particular location for the second color scheme within the, or one of the, standard blank shapes. 
         [0048]    The first and second color scheme and the first and second dimensional information in step  13  are obtained by a blank manufacturer. For example the dental practitioner may send the first and second color scheme and the first and second dimensional information via data transmission (for example via the Internet) to the blank manufacturer. 
         [0049]    The blank manufacturer may prepare one or more dental blanks according to the first and second color scheme and the first and second dimensional information obtained from the dental practitioner. This may be performed for example by using a build-up system in which powder material of different colors are used to build up the blank. A method and system for building up a blank from a powder is for example disclosed in patent application WO 2013/181262 A1. 
         [0050]    In step  14  the dental blank is provided to the dental practitioner or to a dental lab for machining the dental restoration from the blank. 
         [0051]      FIG. 2  illustrates the method  10  in more detail. In step  12  the shape of a patient&#39;s teeth are preferably scanned in the step  121 . Scanning of a patient&#39;s teeth may be performed by directly scanning the natural teeth in the patient&#39;s mouth or by scanning a plaster model which is cast from a dental impression of the patient&#39;s teeth. The scanned shape of the patient&#39;s teeth is provided to CAD (Computer Aided Design) system in step  122  where the dental restoration and/or a blank for making the dental are/is designed. Thus the first and second dimensional information are obtained. The first and second dimensional information are merged in step  15  with the first and second color scheme obtained in step  11  as described in  FIG. 1 . The first and second color scheme as well as the first and second dimensional information assigned for the first and second color scheme, respectively, in step  16  are used to place an order to a blank manufacturer. After manufacturing of the dental blank in step  13  the dental blank is provided to a CAM (Computer Aided Manufacturing) device in step  141  which mills and/or grinds according to step  142  a dental restoration (step  143 ). 
         [0052]      FIGS. 3 to 7  illustrate examples of blanks  100  having at least a first portion  101  based on a first dimensional information according to a first color scheme and a second portion  102  based on a second dimensional information according to a second color scheme. In  FIG. 3  the blank  100  has a first and second uniformly colored portion  101 ,  102 . The first and second portion  101 ,  102  have different colors. The blank  100  is of a cuboid shape and the first and second portion  101 ,  102  are of generally equal size and shape. 
         [0053]    In  FIG. 4  a blank  100  is illustrated which has a first and second uniformly colored portion  101 ,  102  and a third portion  103  which is non-uniformly colored according to a color gradient. The third portion  103  in the example is larger than the first and second portion  101 ,  102 . Thus the blank  100  may be used to machine two differently colored dental crowns and a color graded dental bridge. 
         [0054]      FIG. 5  illustrates a blank  100  having a first portion  101  which may be uniformly or non-uniformly colored. The first portion  101  has outer boundaries corresponding to a part of the outer boundaries of the blank  100 . The blank  100  further has a second portion  102  which is nested within a third portion  103  surrounding the second portion  102 . The second and third portion  102 ,  103  have different colors. Thus a dental restoration may be machined from the second portion  102  only or as an overlap between the second and third portion  102 ,  103 . Accordingly the color of the dental restoration may be controlled by the location at which the dental restoration is machined from the blank. 
         [0055]      FIG. 6  illustrates a blank  100  having a first, a second and a third portion  101 ,  102 ,  103  which in the example each are arch-shaped. The first, second and third portion  101 ,  102 ,  103  further may be non-uniformly colored to resemble the color of natural teeth. Further the first, second and third portion  101 ,  102 ,  103  are nested separate from each other within a fourth portion  104 . 
         [0056]      FIG. 7  shows a dental blank  100  having multiple portions  101 - 107 . The skilled person will recognize further possibilities to shape, size and to arrange portions of different colors within a blank.