Abstract:
Disclosed is a method for digitally designing a dental restoration, wherein a 3D representation of at least a part of the upper or lower jaw is obtained. The 3D representation represents at least a target site for placing the final restoration and at least one antagonist tooth opposing the target site. Furthermore a digital anatomy design of the restoration is provided. The digital anatomy is based at least on a dynamic occlusion and a relative offset of the planned restoration position. Accordingly, a restoration may be designed that does not interrupt the natural occlusion.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention generally relates to digitally designing a dental restoration. In particular it relates to a method for digitally designing a dental restoration where the risk that the dental restoration interferes with the current occlusion/bite of the patient is reduced. 
       BACKGROUND OF THE INVENTION 
       [0002]    When doing restorative work on a patient the dentist always has to be careful not to alter the occlusion of the patient. A changed occlusion may result in a change in chewing motion and bite and may cause discomfort or even pain. 
         [0003]    Accordingly, it is a desire to prevent, or at least reduce the risk, that the occlusion is altered during restorative work. 
       SUMMARY 
       [0004]    Disclosed is a method for digitally designing a dental restoration, comprising:
       obtaining a 3D representation of at least a part of an upper or lower jaw of a patient, representing at least a target site for placing the restoration and at least one antagonist tooth opposing the target site,   providing a digital anatomy design of the restoration based at least on a dynamic occlusion and a relative offset of the planned restoration position.       
 
         [0007]    This has the effect that the anatomy design of the dental restoration can be designed slightly lower than the surrounding teeth and thus the occlusion of the patient is maintained. 
         [0008]    It has even been shown that in many cases the restoration, if it is based on a natural tooth, will naturally move towards the antagonist until in contact during occlusion. 
         [0009]    Accordingly, a restoration may be designed that does not interrupt the natural occlusion and in many cases will in time place itself in a natural position. 
         [0010]    Unless specifically stated herein any reference to occlusion should be understood as dynamic occlusion, i.e. the contact between teeth during movement of a jaws when closed. For example, occlusion does not refer to static occlusion. 
         [0011]    In one embodiment the step of providing the digital anatomy design comprises,
       determining an occlusion boundary defined by the at least one antagonist tooth during the dynamic occlusion,   providing the relative offset by offsetting the occlusion boundary relative to the target site,   generating the digital anatomy design within the occlusion boundary and the neighboring teeth.       
 
         [0015]    This advantageously allows the design of the digital anatomy design in one step, basically automating the anatomy design step. 
         [0016]    In other situations, it may be desirable to modify an existing design. 
         [0017]    Accordingly, in another embodiment the method comprises the steps of,
       designing at least an intermediate anatomy of the restoration, and       
 
         [0019]    wherein the step of providing a digital anatomy design further comprises the steps of,
       determining contact areas between the at least one antagonist tooth and the intermediate anatomy of the restoration based on the dynamic occlusion and the relative offset,   generating the anatomy design of the restoration by modifying the shape of the intermediate anatomy of the restoration at least in the contact areas.       
 
         [0022]    In one embodiment the relative offset is provided by arranging the intermediate anatomy with a predetermined offset distance away from the target site. 
         [0023]    This is particularly advantageous as it allows the contact areas to be determined by performing the dynamic occlusion while the intermediate anatomy is arranged in a relative offset away from the target site. 
         [0024]    In yet another embodiment the relative offset is represented as a threshold distance applied for determining the contact areas during dynamic occlusion. 
         [0025]    In one embodiment, the method further comprises that
       the contact areas are determined by establishing an occlusion surface by tracing the relative teeth movement opposite the target site during dynamic occlusion, and providing the relative offset by offsetting the occlusion surface towards the target site, and   that the anatomy design is generated by using the offset occlusion surface as a cutting surface on the intermediate anatomy.       
 
         [0028]    In addition, when providing an occlusion surface it is not necessary to rerun the dynamic occlusion every time changes are done to the anatomy design, since the occlusion surface shows if there are any areas that need to be modified or reshaped/remodeled. 
         [0029]    In general the relative offset can be provided in many different ways, for example the relative offset is provided by offsetting the target site relative to the jaw, or by offsetting the intermediate anatomy relative to the antagonist, or by offsetting the intermediate anatomy relative to the target site. 
         [0030]    Disclosed is also a nontransitory computer readable medium storing thereon a computer program, where said computer program is configured for executing the steps of the method disclosed herein. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]    The above and/or additional objects, features and advantages of the present invention, will be further elucidated by the following illustrative and non-limiting detailed description of embodiments of the present invention, with reference to the appended drawings, wherein: 
           [0032]      FIG. 1 a -1 c    shows the design steps of a method according to one embodiment of the invention, 
           [0033]      FIG. 2 a -2 d    shows the design steps of a method according to another embodiment of the invention, 
           [0034]      FIG. 3 a -3 c   shows the design steps of a method according to yet another embodiment of the invention, and 
           [0035]      FIG. 4  shows an embodiment of computer system suitable for working the method disclosed herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0036]      FIG. 1 a    shows an upper digital dental model (upper model)  101  and lower digital dental model (lower model)  102 . The digital dental models represents a section of a patients jaw and have been acquired by scanning the respective section of the jaw with an intra oral scanner, for example the TRIOS manufactured by 3Shape TRIOS. The digital dental models could also be obtained from scanning a physical impression or a gypsum model, which both are method known in the art for obtaining digital dental models. 
         [0037]    The upper model  101  has digital representations of three molar teeth  103 ,  104 ,  105  and the lower model  102  has digital representations of two molar teeth  106 ,  107  separated by a target site  108  which in this case is a prepared tooth. 
         [0038]    The dynamic occlusion of the jaw is found by placing the dental models in a virtual/digital articulator. Such virtual articulators are well known and are computer driven simulations and representations of physical articulators, which are used to estimate the jaw movement and occlusion of a patient. By using the representations of the existing teeth  103 ,  104 ,  105 ,  106  and  107  as limitation during dynamic occlusion a very close estimation of the natural dynamic occlusion can be found. In addition, an occlusion surface  110  is found by tracing the surface of the middle molar  104  opposing the preparation during dynamic occlusion. 
         [0039]    The occlusion surface is subsequently offset  111  a desired distance towards the target site along axis A-A as shown in  FIG. 1   b.    
         [0040]    A restoration, such as a crown  109  as shown in  FIG. 1 c    with a digital anatomy design is now modeled on the prepared tooth  108  using the offset occlusion surface  111  and the neighboring teeth  106 ,  107  as design boundaries. 
         [0041]    As can be understood, the digital anatomy design is thus retracted and therefore does not interfere with the occlusion of the existing teeth represented by teeth models  102 ,  103 ,  104 ,  105 ,  106  and  107 . 
         [0042]    In another embodiment an upper digital dental model (upper model)  201  and lower digital dental model (lower model)  202  is obtained, for example by means as previously described above. 
         [0043]    The upper model  201  has digital representations of three molar teeth  203 ,  204 ,  205  and the lower model  202  has digital representations of two molar teeth  206 ,  207  separated by a target site  208  which in this case is a prepared tooth as shown in  FIG. 2   a.    
         [0044]    An occlusion surface  210  is provided by virtual articulation as discussed previously, e.g. in connection with  FIGS. 1 a -1 c    above. 
         [0045]    An intermediate anatomy design  209  of the restoration is provided on the target site. 
         [0046]    A relative offset of the intermediate anatomy design  209  is provided as shown in  FIG. 2 b    by offsetting the intermediate anatomy design  209  along axis B-B away from the target site  208 . 
         [0047]    Based on the occlusion surface  210  the intermediate anatomy design  209  is modified as shown in  FIG. 2 c   . This results in a modified anatomy design  211 , which follows the constraints applied by the software as a result of the occlusion surface  210 . 
         [0048]    Subsequently, as shown in  FIG. 2 d   , the modified anatomy design  211  is placed on the target site  208  and the dental technician can verify the fit e.g. against the neighboring teeth  206  and  207  and provide further modifications if necessary. 
         [0049]    As previously discussed the disclosed method provides a retracted digital anatomy design that does not interfere with the occlusion of the existing teeth represented by teeth models  202 ,  203 ,  204 ,  205 ,  206  and  207 . 
         [0050]    In a third embodiment as shown in  FIGS. 3 a -3 c    the digital steps for designing a restoration are shown. 
         [0051]    A 3D representation of an upper model of the jaw  301  and the lower model of the jaw  302  is obtained. E.g. as disclosed previously in connection with other embodiments or as known in the art. An upper model  301  is provided and has digital representations of three molar teeth  303 ,  304 ,  305  and the lower model  302  has digital representations of two molar teeth  306 ,  307  separates by a target site  308  which in this case is a prepared tooth. 
         [0052]    An occlusion surface  310  is provided by virtually articulating the jaws and tracing the surface of the molar tooth representation  304  during dynamic occlusion, for example as previously described. 
         [0053]    An intermediate anatomy design  309  of a dental restoration is designed using the antagonist tooth  304 , the occlusion surface  310  and the neighboring teeth  306  and  307  as design boundaries. 
         [0054]    The occlusion surface  310  is offset  312  by shifting it towards the target site  308  along line C-C as shown in  FIG. 3   b.    
         [0055]    A modified anatomy design  311  is subsequently provided by using the offset occlusion surface  312  as a design boundary. 
         [0056]    Again, the digital anatomy design is thus retracted and therefore does not interfere with the occlusion of the existing teeth represented by teeth models  302 ,  303 ,  304 ,  305 ,  306  and  307 . 
         [0057]    Other embodiments of digital design methods for providing a digital anatomy design as disclosed herein may be provided within the scope of the claimed invention. 
         [0058]    The method for digitally designing a restoration is provided on computation means for executing the method before a user, such as a dental technician. 
         [0059]    For example, the method is provided in a computer system as shown in  FIG. 4 . The computer system  950  comprises a computer device  951  comprising a computer readable medium  952  and a processor  953 . The system further comprises a visual display unit  956 , a computer keyboard  954  and a computer mouse  955  for entering data and activating virtual buttons visualized on the visual display unit  956 . The visual display unit  956  can be a computer screen/monitor. The computer device  951  is capable of receiving a digital 3D representation of the patient&#39;s set of teeth from a scanning device  957 , such as the TRIOS intra-oral scanner manufactured by 3shape A/S, or capable of receiving scan data from such a scanning device and forming a digital 3D representation of the patient&#39;s set of teeth based on such scan data. The received or formed digital 3D representation can be stored in the computer readable medium  952  and provided to the processor  953 . The processor  953  is configured for executing computer code that allows for the steps of the method for digitally designing a restoration as disclosed herein. The user is guided through the method steps via a user interface visualized on the visual display unit  956 . 
         [0060]    The computer system comprises a unit  958  for transmitting the virtual 3D model to e.g. a computer aided manufacturing (CAM) device  959  for manufacturing the dental restoration or to another computer system e.g. located at a milling center where the dental restoration is manufactured. The unit for transmitting the virtual 3D model can be a wired or a wireless connection. 
         [0061]    Alternatively, or in combination with the computer system as disclosed a cloud based system can be implemented. For example data used for the design steps can be stored remotely on external servers. Such servers could be placed abroad and accessed via the Internet. Even further, the process, or parts thereof, could also be executed on the external servers, such that the user is simply presented with the result of such processes on a visual display unit while the processing occurs remotely. 
         [0062]    Although some embodiments have been described and shown in detail, the invention is not restricted to them, but may also be embodied in other ways within the scope of the subject matter defined in the following claims. In particular, it is to be understood that other embodiments may be utilised and structural and functional modifications may be made without departing from the scope of the present invention.