Patent Publication Number: US-10321959-B2

Title: Method of surgical planning

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of U.S. patent application Ser. No. 13/788,742, filed Mar. 7, 2013, which claims the benefit of U.S. Provisional Application No. 61/648,226, filed May 17, 2012, the contents of both of which are hereby incorporated by reference as if set forth in their entirety herein. 
    
    
     BACKGROUND 
     Surgical planning for orthognathic surgery traditionally combines various diagnostic methods to create a surgical plan and/or to construct a surgical splint that can transfer the surgical plan to the patient in the operating room. According to more recent methods, a 3-D computed tomography (CT) model of the patient&#39;s skull including the patient&#39;s mandible, maxilla, and dentition is obtained using a CT scanner. While the CT scanner provides a good representation of the patient&#39;s bone structure, it is not capable at times of accurately representing the patient&#39;s dentition (i.e. teeth). For example, the dentition represented in the CT model may be obscured or otherwise include “artifacts” due to orthodontic metal brackets, dental fillings, or prosthesis on or near the patient&#39;s dentition. 
     To create a 3-D computer model having a good representation of both the patient&#39;s bone structure and the patient&#39;s dentition, a dental computer model of the patient&#39;s dentition is typically obtained by scanning a negative of an impression (i.e. a plaster cast) of the patient&#39;s dentition with a laser scanner or a CT scanner. Because a plaster cast of the dentition, and not the dentition themselves is scanned, the virtual dental model is not obscured or otherwise “scattered” due to the metal brackets, fillings, or prosthesis. The virtual dental model is then combined with the CT model of the patient&#39;s skull to thereby form a composite computer model that has virtual dentition void of any artifacts. The composite computer model is used to create the surgical plan and/or surgical splint. 
     To align the dental computer model with the dentition of the CT model, metal fiduciary markers are currently used during both the CT scan of the patient&#39;s skull and the scan of the plaster cast. The fiduciary markers of the dental computer model are then aligned with the fiduciary markers of the CT model to form the composite computer model. While the current method is capable of forming a composite computer model that is used to create an orthognathic surgical plan and/or surgical splint, the method is time consuming. Moreover, there remains a desire for more accurate surgical plans and/or surgical splints than those currently provided. 
     SUMMARY 
     A method of pre-operatively forming a surgical splint configured to receive a patient&#39;s dentition can include combining a 3-D facial computer model and a 3-D dental computer model. The method includes the step of obtaining a 3-D facial computer model of at least the patient&#39;s maxilla, mandible, and dentition. The 3-D facial computer model includes first virtual dentition, wherein at least a portion of the first virtual dentition of the 3-D facial computer model has a first virtual surface geometry that defines at least one first fiduciary marker. The method further includes the step of obtaining a 3-D oral scan of a surface geometry of the patient&#39;s dentition so as to produce second virtual dentition. At least a portion of the second virtual dentition has a second surface geometry that defines at least one second fiduciary marker that corresponds to the at least one first fiduciary marker of the 3-D facial computer model. The second fiduciary marker can be aligned with the first fiduciary marker. After the alignment step, the first virtual dentition of the 3-D facial computer model can be replaced with the second virtual dentition to form a composite 3-D virtual model. The composite 3-D virtual model can have third virtual dentition in a planned post-operative configuration. A surgical splint can be custom constructed to match the planned post-operative shape. The surgical splint can have a negative impression of at least a portion of the third virtual dentition. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description of example embodiments, are better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, the drawings show embodiments that are presently preferred. The invention is not limited, however, to the specific instrumentalities disclosed in the drawings. 
         FIG. 1A  is a perspective view of a composite 3-D virtual model of a patient&#39;s skull including a 3-D virtual representation of the patient&#39;s maxilla, mandible and dentition, the maxilla and mandible being positioned into a desired post-operative shape; 
         FIG. 1B  is a top perspective view of a final surgical splint that is configured to align the patient&#39;s maxilla and mandible in the desired post-operative shape, the final surgical splint is custom constructed pre-operatively using the composite computer model of  FIG. 1A ; 
         FIG. 1C  is a bottom perspective view of the final surgical splint shown in  FIG. 1B ; 
         FIG. 1D  is a bottom perspective view of an intermediate surgical splint that is configured to align the patient&#39;s maxilla in its desired post-operative shape prior to the mandible being aligned in its desired post-operative shape, the intermediate surgical splint is constructed pre-operatively using the composite computer model of  FIG. 1A ; 
         FIG. 1E  is a bottom perspective view of the intermediate surgical splint shown in  FIG. 1D ; 
         FIGS. 2A-2E  illustrate steps of a method of creating the composite 3-D virtual model shown in  FIG. 1A  in accordance with an embodiment; 
         FIGS. 3A-3E  illustrate steps of a method of creating the composite 3-D virtual model shown in  FIG. 1A  in accordance with another embodiment; 
         FIG. 4A  is a front elevation view of a composite 3-D virtual model in a pre-operative shape, the composite 3-D virtual model having a virtual maxilla, a virtual mandible, and virtual dentition; 
         FIG. 4B  is a side elevation view of the composite 3-D virtual model shown in  FIG. 4A ; 
         FIG. 4C  is a front elevation view of the composite 3-D virtual model shown in  FIG. 4A  in an intermediate shape, the virtual maxilla being repositioned into its post-operative shape while the virtual mandible remains in its pre-operative shape; 
         FIG. 4D  is a side elevation view of the 3-D composite computer shown in  FIG. 4C ; 
         FIG. 4E  is a front elevation view of the composite 3-D virtual model shown in  FIG. 4C  including a virtual intermediate splint that receives the virtual dentition when the virtual maxilla is in its post-operative shape and the virtual mandible is in its pre-operative shape; 
         FIG. 4F  is a front elevation view of the composite 3-D virtual model shown in  FIG. 4C  in a final post-operative shape, the virtual mandible being repositioned into its post-operative shape along with the virtual maxilla; 
         FIG. 4G  is aside elevation view of the composite 3-D virtual model shown in  FIG. 4F ; 
         FIG. 4H  is a front elevation view of the composite 3-D virtual model shown in  FIG. 4F  including a virtual final splint that receives the virtual dentition when both the virtual maxilla and the virtual mandible are in their post-operative shape; 
         FIG. 5  is a flow chart that describes a method of custom constructing a surgical splint in accordance with an embodiment; and 
         FIG. 6  is a flow chart that describes a method of custom constructing a surgical splint in accordance with another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Certain terminology is used in the following description for convenience only and is not limiting. The words “right”, “left”, “lower” and “upper” designate directions in the drawings to which reference is made. The words “inner” or “distal” and “outer” or “proximal” refer to directions toward and away from, respectively, the geometric center of the implant and related parts thereof. The words, “anterior”, “posterior”, “superior,” “inferior,” “medial,” “lateral,” and related words and/or phrases designate preferred positions and orientations in the human body to which reference is made and are not meant to be limiting. The terminology includes the above-listed words, derivatives thereof and words of similar import. 
     Referring to  FIGS. 1A-1C , a first orthognathic surgical splint  10  can be custom constructed for an individual patient by creating a composite 3-D virtual model  14  of the patient&#39;s skull including at least a virtual representation of the patient&#39;s maxilla, mandible, and dentition. Therefore, the composite 3-D virtual model  14  can include a virtual maxilla  18 , a virtual mandible  22 , and virtual dentition  26 . Using the composite 3-D virtual model  14 , the surgical splint  10  can be custom constructed prior to the surgical operation (i.e. pre-operatively) to match or otherwise conform to a desired and planned post-operative shape of the patient&#39;s skull. 
     As will be described in reference to  FIGS. 2A-2E , the composite 3-D virtual model  14  combines a 3-D dental computer model  30  obtained in a computer from an optical scan of a surface geometry of the patient&#39;s dentition with a separate 3-D facial computer model  34  obtained in the computer from a scan of the patient&#39;s skull. The 3-D dental computer model  30  and the 3-D facial computer model  34  are combined to thereby form the composite 3-D virtual model  14  that includes detailed bone information from the 3-D facial computer model  34  and detailed dentition information from the 3-D dental computer model  30 . 
     Once created, the composite 3-D virtual model  14  can be manipulated into a desired post-operative shape by for example, adjusting the virtual maxilla  18  and/or the virtual mandible  22  of the composite 3-D virtual model  14  relative to the other to correct craniofacial/maxillofacial deformities and/or a cosmetic defect. Using the composite 3-D virtual model  14  after it has been manipulated into the planned post-operative shape, the orthognathic surgical plan and/or the surgical splint  10  can then be custom constructed to match the planned post-operative shape. For example, a computer model or virtual splint can be created in conjunction with the composite 3-D virtual model  14  to match the planned post-operative shape of the patient&#39;s skull. That is, a computer model or virtual splint can be created so as to be configured to receive the virtual dentition  26  after the virtual maxilla  18  and/or the virtual mandible  22  have been repositioned. Information from the computer model or virtual splint can then be transferred to a rapid prototyping machine where the actual surgical splint is fabricated. It should be appreciated, that the planned post-operative shape of the patient&#39;s skull can be substantially similar to the pre-operative shape of the patient&#39;s skull and that the surgical plan and/or surgical splint  10  can be constructed to aid in the correction of a portion of the patient&#39;s skull other than the maxilla and mandible. For example, theatrical plan and/or surgical splint  10  can be constructed to aid in the replacement of a tooth. 
     As shown in  FIGS. 1B and 1C , the surgical splint  10  can include an upper surface  40  and a lower surface  44 . The upper surface  40  can be configured to receive the upper dentition of the patient such as at least a portion of the upper dentition, and the lower surface  44  can be configured to receive the lower dentition of the patient such as at least a portion of the lower dentition when the patient&#39;s mandible and maxilla are in their post-operative shape or positions so as to define the post-operative shape of the patient&#39;s skull. That is, the upper surface  40  of the surgical splint  10  defines a negative impression having contours that correspond to the contours of the upper dentition of the patient when the upper dentition are received by the negative impression, and the lower surface  44  defines a negative impression having contours that correspond to the contours of the lower dentition of the patient when the lower dentition are received by the negative impression, and when both the patient&#39;s maxilla and the patient&#39;s mandible are properly positioned. Therefore, the upper surface  40  will match the upper dentition of the patient, and the lower surface  44  will match the lower dentition of the patient when both the patient&#39;s maxilla and the patient&#39;s mandible have been moved into their desired post-operative shape or positions. In this way, the surgical splint  10  acts as a guide for the orthognathic surgical plan such that the maxilla and the mandible can more easily be aligned into their desired post-operative positions during the surgery. 
     In certain cases and in reference to  FIGS. 1C and 1D , a second orthognathic surgical splint  50  may be desired. For example, in cases where both the maxilla and the mandible of the patient are to be repositioned into a post-operative position or shape, the maxilla can be repositioned and affixed in its post-operative position prior to the mandible being repositioned. The surgical splint  50  can be configured to ensure that the repositioned maxilla is properly aligned into its post-operative position or shape prior to being affixed into position with bone screws. 
     Therefore, the surgical splint  50  can include an upper surface  54  configured to receive the upper dentition of the patient such as at least a portion of the dentition, and a lower surface  58  configured to receive the lower dentition of the patient such as at least a portion of the dentition when the patient&#39;s maxilla is in its post-operative shape or position, and the patient&#39;s mandible is in its pre-operative shape or position. That is, the upper surface  54  defines a negative impression having contours that correspond to the contours of the upper dentition of the patient when the upper dentition are received by the negative impression, and the lower surface  58  defines a negative impression having contours that correspond to the contours of the lower dentition of the patient when the lower dentition are received by the negative impression, and when the patient&#39;s maxilla is properly repositioned and prior to the mandible being repositioned. Therefore, the upper surface  54  will match the upper dentition of the patient, and the lower surface  58  will match the lower dentition of the patient when the patient&#39;s maxilla has been moved into its desired post-operative shape or position. In this way, the surgical splint  50  also acts as a guide for the orthognathic surgical plan. Once the maxilla is affixed to the skull, the mandible can be repositioned using the surgical splint  10 . In this way, the surgical splint  10  can be considered a final surgical splint and the surgical splint  50  can be considered an intermediate surgical splint. It should be appreciated, however, that the mandible can be repositioned prior to the repositioning of the maxilla. Therefore, in cases where both the mandible and the maxilla are to be repositioned, the mandible can be repositioned first using the intermediate surgical splint  50 , and the maxilla can be repositioned second using the final surgical splint  10 . 
     Both the surgical splint  10  and the surgical splint  50  can be manufactured out of a plastic, such as acrylic. The surgical splints  10  and  50  can be machined or otherwise fabricated using a rapid prototyping machine such as a stereolithographic apparatus (SLA mathine). The SLA machine can fabricate the surgical splints  10  and  50  based on the computer models or virtual splints created using the composite 3-D virtual model  14 . It should be appreciated, however, that the surgical splints  10  and  50  can be manufactured out of any material as desired, and that the surgical splints  10  and  50  can be manufactured using any manufacturing method as desired. 
       FIGS. 2A-2E  illustrate a method of forming the composite 3-D virtual model  14  used to create the surgical splints (i.e. surgical splints  10  and  50 ). The method can include all or some of the steps schematically represented as steps  2 A,  2 B,  2 C,  2 D, and  2 E. To form the composite 3-D virtual model  14  and in reference to steps  2 A and  2 C, the 3-D facial computer model  34  and the 3-D dental computer model  30  can be obtained in a computer using respective scanning devices. 
     In step  2 A, the 3-D facial computer model  34  can be obtained by scanning the patient&#39;s skull using any suitable technology. For example, the 3-D facial computer model of the patient&#39;s skull can be obtained by scanning the patient&#39;s skull using any suitable scanner  60 , such as a CT or coronal view cone beam CT scan (CBCT) scanner as illustrated. It should be appreciated, however, that the 3-D facial computer model  34  may be obtained using technology other than a CT scanner, such as a laser scanning machine, an optical scanning machine, or an MRI machine. In operation, scanner  60  can be used to scan the patient&#39;s skull. Scanned data obtained from the scanner  60  can then be downloaded or transferred to a computer. In the computer, the 3-D facial computer model  34  representing the patient&#39;s skull is created from the scanned data using any suitable software capable of processing and editing images. 
     As shown in  FIG. 2B , the 3-D facial computer model  34  can include at least a virtual maxilla  70 , a virtual mandible  74 , and virtual dentition  78 . The virtual maxilla  70 , virtual mandible  74 , and virtual dentition are virtual representations of the patient&#39;s actual maxilla, actual mandible, and actual dentition. The virtual dentition  78  of the 3-D facial computer model  34 , however, can be obscured or otherwise “scattered” (i.e. include artifacts) due to orthodontic metal brackets, dental fillings, or prosthesis that are proximate to the patient&#39;s actual dentition during the scan by the scanner  60 . While the virtual dentition  78  may not have the desired accuracy, at least a portion  82  of the virtual dentition  78  has a first virtual surface geometry that defines a first fiduciary marker  86  that is substantially unobscured by the artifacts. That is, the at least a portion  82  of the virtual dentition  78  can have the necessary accuracy to define a point of reference so as to create a fiduciary marker  86  that can be later used to align the 3-D dental computer model  30  with the 3-D facial computer model  34 . It should be appreciated, that the at least a portion  82  can be any portion of the virtual dentition  78 . It should be further appreciated, that the virtual dentition  78  can have a first virtual surface geometry that defines any number of first fiduciary markers  86 . For example, the virtual dentition  78  can have a first virtual surface geometry that defines at least three first fiduciary markers  86 . 
     In step  2 C, the 3-D dental computer model  30  of the patient&#39;s dentition can be obtained from a 3-D optical intraoral scan or otherwise intraorally imaging the patient&#39;s actual dentition with an intraoral scanner  64  such as with an optical scanner as illustrated. The scanned data can then be downloaded or transferred to a computer such as the same computer as the 3-D facial computer model  34 . In the computer, the 3-D dental computer model  30  representing the patient&#39;s dentition is created using any suitable software capable of processing and editing images. 
     As shown in  FIG. 2D , the 3-D dental computer model  30  more accurately depicts the patient&#39;s actual dentition as compared to the virtual dentition  78  depicted in the 3-D facial computer model  34 . That is, the 3-D dental computer model  30  is substantially free from the artifacts that are produced in the 3-D facial computer model  34  by the scanner  60 . As shown in  FIG. 2D , the 3-D dental computer model  30  includes second virtual dentition  88  that have a second virtual surface geometry that defines at least one second fiduciary marker  90  that corresponds to the at least one first fiduciary marker  86  of the virtual dentition  78  of the 3-D facial computer model  34 . In particular, the second virtual surface geometry of the virtual dentition  88  of the 3-D dental computer model  30  can define a second fiduciary marker  90  that corresponds to each first fiduciary marker  86  of the virtual dentition  78  of the 3-D facial computer model  34 . 
     Unlike the scanner  60 , the scanner  64  is configured to obtain 3-D surface information of the patient&#39;s dentition at a very high degree of accuracy and substantially without any artifacts. The scanner  64  is able to generate the 3-D surface information by moving the scanner directly over the patient&#39;s actual dentition. The scanner  64  obtains coordinates of points or pixels on the surface of the dentition being scanned, which are processed in a computer to calculate the surface configuration of the dentition and subsequently form the 3-D dental computer model  30 . The scanner  64  can include an oscillating microelectromechanical systems (MEMS) mirror and a light source that emits a laser beam toward the oscillating MEMS mirror. The oscillating MEMS mirror reflects the emitted laser beam toward the surface of the patient&#39;s dentition. The surface of the patient&#39;s dentition then reflects the emitted laser beam back to a receiver of the scanner  64 . A processing unit of the scanner  64  records timing parameters of the emitted laser beam and reflected laser beam, and oscillation angles of the oscillating MEMS mirror. The processing unit then computes the 3-D surface configuration of the patient&#39;s dentition and subsequently forms the 3-D dental computer model  30 . It should be appreciated, however, that the 3-D dental computer model  30  can be obtained using any scanner capable of accurately creating an image of the patient&#39;s dentition that is substantially free from artifacts. 
     In step  2 E, the 3-D dental computer model  30  and the 3-D facial computer model  34  can be combined to form the composite 3-D virtual model  14 . The models  30  and  34  can be combined by aligning the at least one second fiduciary marker  9 C) of the virtual dentition  88  of the 3-D dental computer model  30  with the at least one first fiduciary marker  86  of the virtual dentition  78  of the 3-D facial computer model  34 . The virtual dentition  78  of the 3-D facial computer model  34  are thus replaced with the more accurate virtual dentition  88  of the 3-D dental computer model  30  thereby creating a computer model that more accurately represents both the bony structure and the dentition of the patient. Therefore, the virtual maxilla  18 , the virtual mandible  22 , of the composite 3-D virtual model  14  are the same as the virtual maxilla  70 , and the virtual mandible  74  of the 3-D facial computer model  34 , and the virtual dentition  26  of the composite 3-D virtual model  14  are the same as the virtual dentition  88  of the 3-D dental computer model  30 . It can also be said, however, that the virtual dentition  26  of the composite 3-D virtual model are third virtual dentition  26 . Because the 3-D dental and facial computer models  30  and  34  are aligned using first and second fiduciary markers  86  and  90  that are defined by the virtual surface geometries of the virtual dentition of the 3-D dental and facial computer models  30  and  34 , the models  30  and  34  are capable of being aligned without using metal fiduciary markers. 
     The combining step shown in  FIG. 2E  can be performed by a computer program having an algorithm that is capable of matching the fiduciary markers  86  and  90 . While the computer program may be able to substantially align the fiduciary markers  86  and  90 , some manual alignment may be required by the user by moving the virtual dentition  88  of the 3-D dental computer model  30  relative to the virtual dentition  78  of the 3-D facial computer model  34  with for example a computer mouse. It should be appreciated, however, that the fiduciary markers  86  and  90  can be aligned using any method as desired. For example, the user may completely align the fiduciary markers  86  and  90  without the use of a computer program as desired. 
     Once the composite 3-D virtual model  14  is created, the composite 3-D virtual model  14  can then be manipulated into a planned post-operative shape as desired. For example, at least one of the virtual maxilla  18  and the virtual mandible  22  can be repositioned relative to each other or the remainder of the virtual skull into a desired shape or position so as to properly align the third virtual dentition  26  of the composite 3-D virtual model  14  into the desired post-operative configuration. It can also be said, that the third virtual dentition can be displaced into the desired and planned post-operative configuration. Using the planned post-operative configuration of the virtual dentition  26  of the composite 3-D virtual model  14 , the surgical splint(s) can be formed or otherwise fabricated pre-operatively so as to be able to receive the patient&#39;s actual dentition after the patient&#39;s actual maxilla and/or actual mandible have been repositioned into the planned-post operative shape. That is, the surgical splint(s) can be constructed to have a negative impression of a least a portion of the third virtual dentition  26 . In this way, the surgical splint(s) can be custom constructed to match the planned post-operative shape prior to the surgery and act as a guide during the surgical procedure. 
       FIGS. 3A-3E  illustrate a method of forming the composite 3-D virtual model  14  in accordance with another embodiment. The method illustrated in  FIGS. 3A-3E  can include all or some of the steps of the method illustrated in  FIGS. 2A-2E  and are schematically represented as steps  3 A,  3 B,  3 C,  3 D, and  3 E. As shown in  FIGS. 3A-3E , to form the composite 3-D virtual model  14  and in reference to steps  3 A and  3 C, the 3-D facial computer model  34  and the 3-D dental computer model  30  are obtained using respective scanning devices. 
     In step  3 A, the 3-D facial computer model  34  is obtained in a similar manner as described in step  2 A of the method illustrated in  FIGS. 2A-2E . Therefore as in Step  2 A, the 3-D facial computer model  34  of the patient&#39;s skull can be obtained in a computer by scanning the patient&#39;s skull using any suitable scanner  60 , such as a CT or CBCT scanner as illustrated. Also as in Step  2 A, the 3-D facial computer model  34  obtained by the scan includes at least the virtual maxilla.  70 , the virtual mandible  74 , and first virtual dentition  78 . As previously described, the first virtual dentition  78  of the 3-D facial computer model  34  can be obscured or otherwise “scattered” (i.e. include artifacts), however, at least a portion  82  of the first virtual dentition  78  can include a first virtual surface geometry that has the necessary accuracy to define a first fiduciary marker  86 . 
     In step  3 C, the 3-D dental computer model  30  of the patient&#39;s dentition can be obtained in the computer by scanning or otherwise imaging a negative impression  160  of the patient&#39;s actual dentition with the optical scanner  64  rather than directly scanning the patient&#39;s actual dentition as performed in step  2 B of the method illustrated in  FIGS. 2A-2E . 
     In step  3 C, the negative impression  160  of the patient&#39;s actual dentition can be formed using any conventional method. For example, the negative impression  160  can be formed using plaster. It should be appreciated, however, that the impression  160  can be formed using any method as desired. 
     Once the negative impression  160  is formed, the optical scanner  64  can scan the impression  160  to thereby create the 3-D dental computer model  30 . As with the model created in step  2 B, the 3-D dental computer model  30  more accurately depicts the patient&#39;s actual dentition as compared to the virtual dentition  78  depicted in the 3-D facial computer model  34 . That is, the 3-D dental computer model  30  is substantially free from the artifacts that are produced in the 3-D facial computer model  34  by the scanner  60 . The 3-D dental computer model  30  obtained in step B 2  also includes second virtual dentition  88  that have a second virtual surface geometry that defines at least one second fiduciary marker  90  that corresponds to the at least one first fiduciary marker  86  of the first virtual dentition  78  of the 3-D facial computer model  34 . 
     In step  3 E, the 3-D dental computer model  30  and the 3-D facial computer model  34  can be combined to form the composite 3-D virtual model  14  in the same manner described in relation to step  2 E. That is, the models  30  and  34  can be combined by aligning the at least one second fiduciary marker  90  of the second virtual dentition  88  of the 3-D dental computer model  30  with the at least one first fiduciary marker  86  of the first virtual dentition  78  of the 3-D facial computer model  34 . 
     Now in reference to  FIGS. 4A-4H , a method of custom constructing surgical splints, such as surgical splints  10  and  50  using a composite computer model created using one of the methods described in  FIGS. 2 and 3  is illustrated. The method can be used to make both the intermediate surgical splint  50  and the final surgical splint  10  or can be used to make only one of the surgical splints  10  and  50  as desired. Therefore, the method can include all or some of the steps schematically represented in  FIGS. 4A-4H . 
     As shown in  FIGS. 4A and 4B , a composite 3-D virtual model  214  can include a virtual maxilla  218 , a virtual mandible  222 , and third virtual dentition  226 . The composite 3-D virtual model  214  can be obtained using any of the methods described in  FIGS. 2A-2E and 3A-3E . As shown, the composite 3-D virtual model  214  originally represents the pre-operative shape of the patient&#39;s skull. In the illustrated example, the composite 3-D virtual model  214  indicates that the patient&#39;s dentition is not aligned and that as a result, the patient&#39;s maxilla and mandible need to be translated and rotated. Though it should be appreciated, that the patient&#39;s maxilla and/or mandible can be manipulated in any manner desired. 
     With continued reference to  FIGS. 4A and 4B , first and second virtual osteotomies  230  and  234  can be performed on the virtual maxilla  218  and virtual mandible  222  of the composite 3-D virtual model  214 . As shown in  FIGS. 4C and 4D  the composite 3-D virtual model  214  can be manipulated into a desired intermediate shape. For example, the virtual maxilla  218  can be repositioned into its desired post-operative shape or position while the virtual mandible  222  remains in its pre-operative shape or position to thereby define an intermediate shape of the skull. As shown, the virtual maxilla  218  can be rotated and advanced forward a desired amount as illustrated to thereby reposition the virtual maxilla  218  into the desired post-operative shape or position. It should be appreciated, however, that the virtual maxilla  218  can be repositioned in any manner necessary to place the virtual maxilla  218  into its desired post-operative shape or position or configuration. 
     While the composite 3-D virtual model  214  is in its intermediate shape, and thus prior to repositioning the virtual mandible  222 , a virtual intermediate surgical splint  240  can be created to match the intermediate shape of the composite 3-D virtual model  214 , for example as shown in  FIG. 4E . That is, the virtual intermediate surgical splint  240  can be created such that the virtual intermediate surgical splint  240  receives the third virtual dentition  226  when the virtual maxilla  216  is in its post-operative shape or position and the virtual mandible  222  is in its pre-operative shape or position. Using the data from the virtual intermediate surgical splint  240  the physical or actual intermediate splint (i.e. surgical splint  50  shown in  FIGS. 1C and 1D ) can be fabricated on a rapid prototyping machine. In this way, the actual intermediate splint is fabricated to match the virtual intermediate splint. It can also be said, that the actual intermediate splint is constructed to have a negative impression of at least a portion of the third virtual dentition  226  when the third virtual dentition are in an intermediate configuration. Therefore, the actual intermediate splint can be used during the surgery to reposition the patient&#39;s actual maxilla into the desired post-operative shape or position as planned on the composite 3-D virtual model  214 . 
     As shown in  FIGS. 4F and 4G  the composite 3-D virtual model  214  can be manipulated into a desired final or post-operative shape. For example, with the virtual maxilla  218  already repositioned into its desired post-operative shape or position or configuration, the virtual mandible  222  can now be repositioned into its desired post-operative shape or position or configuration to thereby define the final post-operative shape of the skull. As shown, the virtual mandible can be rotated and advanced forward a desired amount as illustrated to thereby reposition the virtual mandible  222  into the desired post-operative shape or position. It should be appreciated, however, that the virtual mandible  222  can be repositioned in any manner necessary to place the virtual mandible  222  into its desired post-operative shape or position. 
     While the composite 3-D virtual model  214  is in its final or post-operative shape, a virtual final surgical splint  244  can be created to match the desired post-operative shape of the composite 3-D virtual model  214 . That is, the virtual final surgical splint  244  can be created such that the virtual final surgical splint  244  receives the third virtual dentition  226  when both the virtual maxilla  216  and the virtual mandible  222  are in their post-operative shapes or positions or configurations. Using the data from the virtual final surgical splint  244  the physical or actual final splint (i.e. surgical splint  10  shown in  FIGS. 1B and 1C ) can be fabricated on a rapid prototyping machine. In this way, the actual final surgical splint is fabricated to match the virtual final surgical splint. It can also be said, that the actual final splint is constructed to have a negative impression of at least a portion of the third virtual dentition  226  when the third virtual dentition are in a final post-operative configuration. Therefore, the actual final surgical splint can be used during the surgery as a guide to reposition the patient&#39;s actual mandible into the desired post-operative shape or position as planned on the composite 3-D virtual model  214 . It should be appreciated, however, that in some cases only a single surgical splint may be desired to reposition the patient&#39;s mandible and/or the patient&#39;s maxilla. Moreover, it should be appreciated that a surgical splint may be custom constructed to be a guide for a surgical procedure that does not involve repositioning the patient&#39;s maxilla and/or the patient&#39;s mandible. For example, a surgical splint may be custom constructed to be a guide for a surgical procedure that requires the placement of a tooth implant. 
     With reference to  FIG. 5 , a method  300  of pre-operatively forming a surgical splint configured to receive a patient&#39;s dentition when the patient&#39;s skull is in a desired post-operative shape can include steps  304 ,  308 ,  312 ,  316 , and  320 . In step  304  a 3-D facial computer model of at least the patient&#39;s maxilla, mandible, and dentition can be obtained in a computer. The 3-D facial computer model can include first virtual dentition, and at least a portion of the first virtual dentition of the 3-D facial computer model can have a first virtual surface geometry that defines at least one first fiduciary marker. In step  308 , a 3-D dental computer model of the patient&#39;s dentition that more accurately depicts the patient&#39;s dentition as compared to the dentition depicted in the 3-D facial computer model is produced by obtaining a 3-D optical scan of a surface geometry of the patient&#39;s dentition. The 3-D dental computer model can include second virtual dentition that can have a second surface geometry that defines at least one second fiduciary marker that corresponds to the at least one first fiduciary marker of the 3-D facial computer model. In step  312 , the 3-D dental computer model and the 3-D facial computer model can be combined to form a composite 3-D virtual model by aligning the at least one second fiduciary marker of the 3-D dental computer model with the corresponding at least one first fiduciary marker of the 3-D facial computer model. In step  316 , the composite computer model can be manipulated into a planned post-operative shape. In step  320  a physical surgical splint can be pre-operatively custom constructed to match the planned post-operative shape, and the physical surgical splint can be configured to receive the patient&#39;s dentition when the patient&#39;s skull is in the desired post-operative shape. 
     In step  304 , the 3-D facial computer model can be obtained in a computer by scanning the patient&#39;s skull with a CT scanner. In step  308 , the 3-D dental computer model can be obtained in the computer by intraorally imaging the patient&#39;s dentition. For example, the 3-D dental computer model can be obtained by directly scanning the patient&#39;s dentition with an intraoral scanner, such as an optical scanner. In step  312 , the 3-D dental computer model and the 3-D facial computer model can be combined without the use of metal fiduciary markers. In step  316  the composite computer model can be manipulated by repositioning at least one of the virtual maxilla and the virtual mandible. The method of  FIG. 5  can further include the step of creating a virtual surgical splint model to match the planned post-operative shape, and the step of custom constructing the surgical splint comprises fabricating the surgical splint to match the virtual surgical splint model. 
     With reference to  FIG. 6 , a method  400  of pre-operatively forming a surgical splint configured to receive a patient&#39;s dentition when the patient&#39;s skull is in a desired post-operative shape can include steps  404 ,  408 ,  412 ,  416 ,  418  and  420 . In step  404  a 3-D facial computer model of at least the patient&#39;s maxilla, mandible, and dentition can be obtained in a computer. The 3-D facial computer model can include virtual dentition, wherein at least a portion of the virtual dentition of the 3-D facial computer model has a first virtual surface geometry that defines at least one first fiduciary marker. In step  408 , a dental impression of the patient&#39;s dentition can be formed. In step  412 , a 3-D dental computer model of the patient&#39;s dentition can be obtained in a computer by scanning the dental impression with an optical scanner. The 3-D dental computer model can include second virtual dentition, wherein the second virtual dentition of the 3-D dental computer model have a second virtual surface geometry that defines at least one second fiduciary marker that corresponds to the at least one first fiduciary marker of the 3-D facial computer model. In step  416 , the 3-D dental computer model and the 3-D facial computer model can be combined to form a composite 3-D virtual model by aligning the at least one second fiduciary marker of the 3-D dental computer model with the corresponding at least one first fiduciary marker of the 3-D facial computer model. In step  418 , the composite computer model can be manipulated into a planned post-operative shape. In step  420  a surgical splint can be custom constructed to match the planned post-operative shape. The surgical splint can be configured to receive the patient&#39;s dentition. In step  416 , the first virtual dentition of the 3-D facial computer model can be combined with the second virtual dentition of the 3-D dental computer model without the use of metal fiduciary markers. 
     It should be noted that the illustrations and discussions of the embodiments shown in the figures are for exemplary purposes only, and should not be construed limiting the disclosure. One skilled in the art will appreciate that the present disclosure contemplates various embodiments. For example, although the present disclosure refers to three-dimensional computer models, it is envisioned that any of the computer models described in the present disclosure can be two-dimensional. It should be further appreciated that the features and structures described and illustrated in accordance with one embodiment can apply to all embodiments as described herein, unless otherwise indicated. Additionally, it should be understood that the concepts described above with the above-described embodiments may be employed alone or in combination with any of the other embodiments described above.