Abstract:
A dental surgical drill guide assembly and method includes a surgical guide housing and a base frame that fits to both gum tissue and one or multiple small areas of jawbone. The apparatus may be configured to accurately place dental implants according to planned positions. Such apparatus may increase the stability of the surgical guide by clasping and/or contacting the jawbone, while improving the overall fit and minimizing the need of invasive surgery and flapping by also clasping and/or contacting selected areas of the gum tissue at the same time. Self-locking alignment members aid in easy removal, and re-installation, of the surgical guide housing to the base frame.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 61/535,698, filed Sep. 16, 2011, which is hereby expressly incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    An improved dental implant method and apparatus is disclosed, and, more particularly, a surgical guide that can be fit to a patient&#39;s jawbone. 
       BACKGROUND AND SUMMARY OF THE INVENTION 
       [0003]    Dental implants are commonly used in today&#39;s dental practices to support various prostheses. Challenges to the successful placement of dental implants include poor bone quality and various hidden anatomical features such as nerves, roots, and sinus cavities. Surgical preplanning methods and drill guide apparatuses may be used to better address these challenges. With edentulous cases, surgical drill guide apparatuses can be divided into two categories: bone borne surgical drill guides and gum tissue borne surgical guides. 
         [0004]    Bone borne surgical drill guides are made to fit on a patient&#39;s jawbone, and can be made from either a digital jawbone model or rapid-prototyped physical jawbone model of the patient. The primary problem with bone borne surgical guides is the invasiveness of the amount of flapping of the gum tissue that the surgeon has to create in order for the guide to fit correctly on the patient jawbone. The amount of flapping required increases the likelihood of surgical risks and complications, including blood loss, infection, healing problems, and overall pain experienced by the patient. Flapping and suturing also requires a great deal of surgical time. In addition to the problems associated with the surgical procedure, difficulties may also arise when the jawbone has low density, which happens often with Maxilla bones in posterior region. Low bone density makes it difficult to define the contour of the bone in CT images, which may cause the bone borne surgical drill guide to fit poorly. Thus, the use of bone borne surgical drill guides has drawbacks and it would be preferred to overcome their associated problems. 
         [0005]    Gum tissue borne surgical drill guides are made to fit on top of a patient&#39;s gum tissue without the need for any surgical incisions to stabilize the guide. In order to create this type of surgical guide, the surface scan data of the gum tissue and the tomography data of the jawbone need to be accurately aligned and mapped. For this purpose, usually an imaging template is worn by the patient during tomography scanning, and the fiducial markers on the device are used for alignment of the different data sets. While this method is less surgically invasive than the bone borne method, gum tissue borne surgical guides lack stability. Gum tissue is in a constant state of movement and drift, and is also pliable with pressure. Moreover, certain health conditions and even the intake of certain foods make gum tissue more prone to swelling. These conditions may prevent the accurate positioning of the device in the mouth. Here, even if the surgeon uses anchor screws, they may be securing the device in the wrong position. This type of surgical drill guide sacrifices accuracy for convenience. Thus, it would be preferred to overcome these problems. 
         [0006]    Accordingly, it would be desirable to provide a stable and accurate surgical drill guide apparatus that requires only minimum flapping and fits to both gum tissue and one or multiple small areas of jawbone. Such apparatus may increase the stability of the surgical guide by clasping and/or contacting the jawbone, while improving the overall fit and minimizing the need of flapping by also clasping and/or contacting selected areas of the gum tissue at the same time. The apparatus may be configured to accurately place dental implants according to the planned positions. 
         [0007]    It would also be preferable to provide an apparatus that may be custom designed to suit the unique anatomical features of each individual. The device may be designed on a digital anatomical jawbone model with accurately mapped and aligned gum tissue information, and may be rapid prototyped or milled as a drill guide frame or frame set. Also, the apparatus may be made by hand on the rapid prototyped or CNC milled physical anatomical model that partially exposes the jawbone structure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1A  is a top view of an upper jaw anatomical diagnostic model with gum tissue and a partially exposed bone structure; 
           [0009]      FIG. 1B  is a perspective front view of a lower jaw anatomical diagnostic model with gum tissue and a partially exposed bone structure; 
           [0010]      FIG. 1C  is a perspective front view of a lower jawbone digital image and a gum tissue image which are about to be aligned; 
           [0011]      FIG. 1D  is a perspective front view of a lower jaw bone digital image aligned with the gum tissue digital image; 
           [0012]      FIG. 2A  is a top view of an exemplary base frame for an upper jaw on a diagnostic model with gum tissue and a partially exposed bone structure; 
           [0013]      FIG. 2B  is a side view of the exemplary base frame for the upper jaw on  FIG. 2A  diagnostic model; 
           [0014]      FIG. 2C  is a bottom view of the exemplary base frame for the upper jaw shown in 
           [0015]      FIG. 2A ; 
           [0016]      FIG. 2D  is a top view of an exemplary base frame for a lower jaw on a diagnostic anatomical model with gum tissue and a partially exposed bone structure; 
           [0017]      FIG. 2E  is a perspective front view of the exemplary base frame for the lower jaw on the same anatomical diagnostic model shown in  FIG. 2D ; 
           [0018]      FIG. 2F  is a perspective view of an exemplary base frame for the upper jaw; 
           [0019]      FIG. 3A  is a side view of the exemplary drill guide housing frame for the upper jaw about to be attached to the exemplary base frame on the anatomical model; 
           [0020]      FIG. 3B  is a top view of the  FIG. 3A  drill guide housing frame, with skirted area on the base frame and the physical anatomical diagnostic model; 
           [0021]      FIG. 3C  is a side view of the  FIG. 3A  drill guide housing frame, with a hand piece drilling holes into the skirted areas; 
           [0022]      FIG. 3D  is a top view of the  FIG. 3A  exemplary drill guide housing frame, with holes that correspond with planned osteotomies on the physical anatomical diagnostic model; 
           [0023]      FIG. 3E  is a side view of the  FIG. 3D  physical anatomical diagnostic model, with positioning pins and drill guide bushings placed into the planned osteotomies through the holes on the skirt portion of the drill guide housing frame; 
           [0024]      FIG. 4A  is a top view of an exemplary drill guide section for the upper jaw placed on the base frame and the physical anatomical diagnostic model; 
           [0025]      FIG. 4B  is a perspective view of the  FIG. 4A  anatomical diagnostic model with base frame and positioning pins, showing intersecting osteotomy angulations; 
           [0026]      FIG. 4C  is a top view of an exemplary interchangeable additional drill guide section with a tube surgical drill guide bushing; 
           [0027]      FIG. 4D  is a top view of an exemplary surgical drill guide section for the lower jaw placed on the base frame and the physical diagnostic anatomical model; 
           [0028]      FIG. 5  is a perspective view of an exemplary modified denture duplicate attachment for an upper jaw attached to a base frame; 
           [0029]      FIG. 6A  is a perspective front view of an exemplary anatomical diagnostic model with a partially exposed lower jaw bone before adjustment; 
           [0030]      FIG. 6B  is a perspective front view of the exemplary anatomical diagnostic model with a partially exposed modified lower jaw bone with planned osteotomies; 
           [0031]      FIG. 6C  is a perspective front view of an exemplary base frame on the diagnostic anatomical model; 
           [0032]      FIG. 6D  is a perspective front view of an exemplary drill guide section placed on the base frame and the anatomical diagnostic model; 
           [0033]      FIG. 7  is a perspective view of an exemplary one piece drill guide on a physical anatomical diagnostic model; 
           [0034]      FIG. 8  is an exploded perspective view of the  FIG. 6D  drill guide assembly; 
           [0035]      FIG. 9  is an exploded perspective view of another exemplary drill guide assembly; 
           [0036]      FIG. 10  is the  FIG. 9  drill guide assembly in assembled form; 
           [0037]      FIG. 11  is a bottom perspective exploded view of the  FIG. 8  assembly; 
           [0038]      FIG. 12  is the base frame of the  FIG. 9  drill guide assembly shown positioned within the mouth of a patient. 
           [0039]      FIG. 13  is a diagram of the edentulous surgical drill guide manufacturing process for a model based implant placement planning; 
           [0040]      FIG. 14  is a diagram of the edentulous surgical drill guide manufacturing process for a digital implant placement planning; and 
           [0041]      FIG. 15  is a diagram of how to utilize the edentulous surgical drill guide during the surgery. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0042]    Referring now to the discussion that follows and also to the drawings, illustrative approaches are shown in detail. Although the drawings represent some possible approaches, the drawings are not necessarily to scale and certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the present disclosure. Further, the descriptions set forth herein are not intended to be exhaustive or otherwise limit or restrict the claims to the precise forms and configurations shown in the drawings and disclosed in the following detailed description. 
         [0043]      FIGS. 1A and 1B  illustrate patient specific digital or physical dental anatomical diagnostic models  100  and  101  that expose the partial upper jawbone bone structures  103  and a lower jawbone  104  at the surgical sites and the areas of interest. In areas where the bone structures are not exposed, the model has gum tissue surface structures  102 . As in  FIGS. 1A and 1B , these gum tissue surface structures  102  usually appear towards the distal end of the posterior regions and the palatal area of the upper jaws. 
         [0044]      FIGS. 1C and 1D  depict a digital image of a lower jawbone  104  and a digital image of the gum tissue surface structures  102  positioned relative to one another, from which diagnostic anatomical models like  1 A and  1 B are created. 
         [0045]    The bone structure data can be obtained by tomography imaging devices such as CT and CB CT, and may be exported as a file format, such as STL, suitable for reverse engineering and 3D imaging. Then the data file can be accurately aligned with the surface scan data of the gum tissue  102  obtained by devices such as laser and optical scanners by means of matching fiducial markers on the imaging apparatus that the patient wears during the tomography scan to the markers&#39; positional information on the surface scan data. If the bottom of the apparatus represents the patient&#39;s gum tissue surface, the image of the patient&#39;s gum surface can also be obtained by scanning the imaging apparatus alone using a tomography device. In this case, these two CT data files can be aligned by the fiducial marker location(s) after each structure is thresholded and is exported as a proper file format for modeling. If a radio opaque duplicated denture is used as an imaging apparatus, the bone structure data and the gum surface data can be obtained with a single CT scan of the patient with the imaging apparatus in place. After the necessary structures are properly aligned in a file format suitable for 3D modeling, the data files can be combined and used to design a digital anatomical diagnostic model with a partially exposed bone structure in the area of the surgical site. 
         [0046]    The osteotomies of simulated dental implant placements  105  may be created either digitally on the digital anatomical diagnostic model or manually on the rapid-prototyped physical anatomical diagnostic model. Then a drill guide apparatus may be designed on this type of digital anatomical diagnostic model so that it will accommodate drill guide bushings or holes which guide the surgical drill according to the planned osteotomies either on the digital anatomical diagnostic model or the physical anatomical diagnostic model. Alternatively, the whole apparatus can be designed manually on this type of physical anatomical diagnostic model with dental materials such as, but not limited to, light cured composite, cold cured resin or acrylic, or thermoplastic. 
         [0047]      FIGS. 2A-E  are exemplary designs of a base frame  200  for an upper jaw ( FIGS. 2A-2C ) and a lower jaw ( FIGS. 2D &amp; 2E ). The base frame  200  may be made of a transparent or semi-transparent resin or other composite material that gives the surgeon maximum visibility of the surgical site, but it may also be made of a colored resin and other composite material or metal that provides the base frame  200  with enough rigidity for stability and the right amount of flexibility in clasping areas. In order to obtain rigidity and flexibility in different areas, the frame  200  may be designed to have thick areas and thin areas accordingly within the frame. Overall however, the base frame can be more flexible than one piece surgical guide since the surgical drill guide section placed on top of it can solidify the whole drill guide assembly and the flexibility allows the device to clasp on to the undercut easily. The base frame  200  is shown positioned on top of the upper jawbone structure  103 . A plurality of osteotomies of simulated dental implant placements  105  are shown about the periphery of the upper jawbone structure  103 . A handle  203  is secured towards a forward portion of the base frame  200  which is used to aid in the maneuverability of the base frame  200 . Interlocking connectors  204  are firmly mounted to, or formed part thereof, the base frame  200 , and provide guides for the surgical drill guide housing frame  300  to connect thereto. The arrows  20  depict potential pressure impinging points for the drill guide housing frame  300  to impinge upon. 
         [0048]      FIG. 2D  shows a base frame  200  on the type of anatomical models explained above, and gum tissue contact portions  201  are placed on the gum tissue areas of the model. Although this portion may have broad area contacts with the gum tissue  102 , it may also have strategically placed smaller spot contact areas  205  as shown in  FIG. 2C . In some designs, certain areas of gum tissue contact portion can be used to place temporary anchors through the gum tissue into the patient jawbone by small screws, pins or other fastening devices. 
         [0049]    The surgical device  200  may also have one or more clasping lateral contacts  202  (See  FIGS. 2B-2E ) that may simply contact the lateral wall of the exposed jawbone  103  and  104  or engage its undercut. As shown in one exemplary design of the base plate  200  for a lower jaw  104  ( FIGS. 2D &amp; 2E ), clasping lateral contacts  202  may be connected to the gum tissue contact portion  201  by stabilizing/clasping arms  207  that may or may not have contact with the oral structure. The stabilizing/clasping arms  207  extend out from a base frame  200  and/or drill guide housing frame  300  which may be turn into a drill guide housing section  400  with drill guide bushings. When the frame is placed on the oral structure or anatomical diagnostic model, the stabilizing/clasping arms  207  slightly flex out and then clasp securely onto the oral structure  104 . Although the stabilizing/clasping arms  207  are illustrated as peninsulas that extend out of the tissue contact area, the stabilizing/clasping arms  207  may be continuously connected to the tissue area like in the exemplary base frame  200  shown in  FIG. 2F . Clasping lateral contact area  202  may also be used for placing a temporary anchor directly into the jawbone  104  if the patient&#39;s oral structure does not allow the device to have enough retention. 
         [0050]    Similar to the clasping lateral contacts  202 , one or more occlusal/lateral stabilizing rests  206  ( FIG. 2D ) may be strategically placed to contact the jawbone  104  to work along with the gum tissue contact portion  201  and the clasping lateral contact  202  in order for the device  202  to be securely positioned inside of the patient&#39;s oral structure (See  FIG. 12 ). This section may also be connected to the gum tissue contact portion  201  by at least one stabilizing/clasping arm  207 . 
         [0051]    The arrows on  FIGS. 2A ,  2 E and  6 C indicate the direction of force  20  applied from each contact point to the oral structure, and show how stabilizing/clasping arms  207  help fixate the device  200  in place. 
         [0052]    Although it is not illustrated, due to a particular shape of the jawbone  103 ,  104 , the base frame  200  may be designed to have only tissue contacts without any jawbone contact and to have a separate detachably attachable part that snaps onto it and engage the jawbone. Alternatively, this bone clasping part can be a latch connected to the base frame  200  by a hinge. 
         [0053]    The base frame  200  may also include a handle  203  on  FIGS. 2A-2C  that may be used when removing the device from the oral structure, and an interlocking connector  204  ( FIGS. 2A ,  2 B,  2 D,  2 E) that securely connects the base frame  200  to a surgical drill guide housing frame  300  ( FIGS. 3A-3E , and  FIGS. 4A , &amp;  4 C). The handle  203  may also be a handle/connector, a part of which works as a male interlocking connector.  FIG. 2F  illustrates the base frame  200  having connectors  204  that are secured to the upper service thereof. Stabilizing arms  207  are positioned around its outer periphery with openings  208  being positioned adjacent thereto. 
         [0054]      FIG. 3A  illustrates an exemplary drill guide housing frame  300  configured to be disposed on the base frame  200 , which collectively form an assembly  310 . Material requirements for the drill guide housing frame  300  are same as the specifications for the base frame  200 . The drill guide housing frame  300  may securely snap onto the base frame  200  by the interlocking connectors  204  ( FIGS. 2A ,  2 C,  2 D,  2 E) and the connector receptors  304  ( FIG. 3B ), also by the handle  203  and handle/connector receptors  303  ( FIGS. 3A-3D ), along with various stabilizing rests and/or clasping contact areas between the two devices  200 ,  300 . As illustrated, the interlocking connectors  204  on the base frame  200  may be male connectors with strategically placed slight undercuts, and the connector receptors  302  and  303  on the drill guide housing frame  300  may be female connectors. However, various types of different connector mechanisms can be used for this purpose. Similar to the handle/connector  203  on the base frame  200 , the handle/connector receptor  303  may be used when removing the device from the base frame  200 , and it may also be used as a receptor for the handle/connector  203 . Similar to the contact points/areas of the base frame to the oral structure, the drill guide housing frame  300  may have clasping or resting contact points/areas to the base frame  200  besides the connectors. These contact points/areas may be strategically placed to work together along with the connectors not only to ensure a secure fit of the part to the base frame  200  but also to lock in the entire device (the base frame and the drill guide housing section) onto the oral structure by adding an extra layer of thickness and applying more clasping force. The base frame  200  and the surgical drill guide housing  300  may be designed to work together to make the assembly  310  set snugly fit onto the oral structure  100  and yet have great rigidity so that it is very stable in the patient&#39;s mouth as well as on the physical anatomical diagnostic model. Although not illustrated, the frames may be fastened together using any other suitable fasteners including, but not limited to, screws, pins and latches. 
         [0055]    The holes  304  on the connector receptors  302  and handle/connector receptor  303  shown on  FIGS. 3B and 3D  are liquid escape holes  304  that allow excess moisture and debris to escape so that they will not be trapped in-between the devices  200  and  300 . It should be noted that the liquid escape holes  304  can be created in different areas of the drill guide housing frame  300 . The larger opening holes  305  in the middle of the devices  300  and  401  in  FIGS. 4A and 4C  are clearance openings for fastening anchor devises such as screws and pins that are used to fasten the base frame  200  onto the jawbones  103  and  104  without engaging with the drill guide housing frame  300 . However, the larger opening holes  305  may also be used as liquid escape holes  304 . 
         [0056]    Unlike the handles  203  and  303 , other exemplary handles may not have a connecting function. The handles may be on either one or both of the base frame  200  and the drill guide housing frame  300 , and there may be more than one handle  203  and  303  on both frames. Moreover, the handles on the base frame  200  and the drill guide housing frame  300  can work together as a combination handle unit. Ideally, the combination handle unit is designed to leave a small space at least in a certain area between the devices&#39; handles so that a hand instrument or other types of tools can be inserted into the space to pry the frames apart. Also, similar spaces  601  for the instrument may be created between the frames in other areas to make the separation of the frame easier. See  FIGS. 6D ,  8  and  11 . 
         [0057]    Optionally, the device may also feature skirted areas  301  ( FIG. 3B ) over the intended surgical site(s). This feature may be useful when the surgeon plans the osteotomies  105  on a physical anatomical model and the device is rapid prototyped or CNC milled from the design created on the digital anatomical model. The skirted areas may be a thin shell that extends from the device  300  and covers the intended surgical site(s). The purpose of this feature is to provide base structure for the surgical drill guide site(s). When the osteotomies are planned on a rapid-prototyped or milled physical anatomical model, the implant positions and angulations are unknown at the time of manufacturing of the surgical drill guide frame or frame set. By having a thin skirted area  301  over the intended implant site as a base structure, it may be easier to prepare the surgical drill guide site(s) on the device  300 . Also, the skirted area  301  can be made so that the top surface or the bottom surface of the section represents the patient&#39;s gum tissue  102 . It can also be made so that the bottom surface of the section sits on top of the bone, a certain distance away from the bone below or above the gum tissue. By going through the procedure that is shown on  FIG. 3C , the holes  306  that correspond with the planned osteotomies  308  will be created on the skirt as shown on  FIG. 3D . Drill  306  is used to create the holes  306 . When the surgical drill guide sites are prepared on the physical anatomical model  100 , positioning pins  308  may be used to set the angulations of the osteotomies and to position the surgical drill guide parts  309  as shown in  FIG. 3E . 
         [0058]      FIG. 4A  illustrates an exemplary surgical drill guide section  400  that was trimmed after surgical drill guide sites are prepared so that the device  400  may provide improved surgical site visibility and good facility for irrigation. Optionally, metal or ceramic tube type  309   a  or open-face type  309   b  surgical drill guide bushings can be attached to the device  400 , but the device may not have any added parts to the drill guide site. If the implant placement is digitally planned on the digital anatomical model prior to the model manufacturing, the drill guide housing frame  300  can be digitally designed like this illustration, without any skirted area  301 , so that the drill guide bushings  309   a  and  309   b  can be attached to the device  400  right after manufacturing. Another exemplary surgical drill guide section  400  shown in  FIG. 4D  for a lower jawbone  101  snapped on to the base frame  200  illustrates the space  105  between jawbone surface  103  and the bottom of the drill guide housing frame  400  over the surgical site, which may be preferred by surgeons for the better irrigation. However, as previously described, the bottom surface of the drill guide housing frame may be set at a different height. 
         [0059]      FIG. 5  illustrates the modified duplicated denture appliance  500  attached to the base frame  200 . One way of creating this appliance is to scan the patient&#39;s denture or duplicated denture surfaces, align the data to the anatomical model, and modify it to fit on the base frame  200 . This appliance  500  may have features such as connector receptors  302 , irrigation holes  304 , and openings for fastening anchor devices  304  just like a surgical drill guide housing frame  300 . This appliance  500  may be used to verify the position of the base frame or the single piece surgical guide with patient&#39;s bite. Other examples of attachments include, but are not limited to, an implant pick up impression tray, an implant transfer jig tray, and a bone adjustment jig. 
         [0060]    Advantages of the drill guide assembly  310  having the base frame  200  and the drill guide housing frame  300  may include: 1) Interchangeable multiple guide frames  300  can be used during the surgery while the base frame  200  can be securely positioned in the patient oral structure; 2) If, for any reason, the doctor changes the positioning of one or more of the implants from the original plan, and cannot use the surgical drill guide for those particular site(s), or needs to work on the bone, he/she can temporarily remove the drill guide housing frame  300  from the base frame  200  without disturbing the position of the base frame  200 ; 3) Various types of additional attachments can be placed on the base plate  200  without the drill guide parts covering the surgical sites. The drill guide assembly  310  is especially beneficial when the base frame needs to be temporarily anchored to the patient&#39;s jawbone. 
         [0061]    More than one surgical drill guide section  400  may be needed in order to accommodate a surgery&#39;s specific needs. As illustrated with the positioning pins  308   a  and  308   b  in  FIG. 4B , two of the intended osteotomies  105   a  and  105   b  are very close to each other and have intersecting positioning angulations. In this case, a second surgical drill guide section,  401  in  FIG. 4C  may be created for one of the planned osteotomies  105   a . This type of additional surgical guide section  401  is detachably attachable to the base frame  200  and is interchangeable with the first surgical drill guide section  400 . Alternatively, smaller parts that house the surgical drill guide bushings  309  or drill guide holes for specific implant placement sites may be attached to the first surgical drill guide section  400 . Although it is not illustrated, another benefit for having additional surgical drill guide section  401  is to accommodate larger size surgical drill guide bushings,  309   a  and  309   b  that are subsequently used for finish drilling osteotomies  105 . 
         [0062]      FIGS. 6A-6D  represent a situation in which the doctor decides to reduce the jawbone prior to implant placement.  FIG. 6A  is an anatomical diagnostic model of a lower jaw  101  which shows a gum tissue portion  102  and a partially exposed bone structure  104 . The doctor may wish to modify the bone  104   b  prior to the implant placement as in  FIG. 6B . In this case, the base frame  200  ( FIG. 6C ) may be designed according to the doctor&#39;s specification either on the digital model or the physical anatomical diagnostic model so that it can be used as a bone reduction jig.  FIG. 6C  illustrates a base frame ( 200 ) on an anatomical diagnostic model with a modified lower jawbone  104 . A drill guide section  400   FIG. 6D  may be designed on top of the base frame  200  to be used for implant placement. 
         [0063]    Various types of additional detachably attachable appliances can be added to the surgical drill guide  400 . One example of an additional appliance is a modified duplicated denture attachment  500 . 
         [0064]    It will be appreciated that the surgical drill guide can be manufactured as single piece  700  ( FIG. 7 ) that contacts both gum tissue and exposed bone. Single piece apparatus  700  has combined functions of both base frame  200  and the surgical drill guide section  300 . The device may have all or some of the features described above, or it may include different types of attachments. Lateral contacts  202  on the forward edge are connected to an arm  207 , which may be a part of the single piece guide  700 . 
         [0065]      FIG. 8  is an exploded view of a two part surgical drill guide assembly  401  that is shown in  FIG. 6D . The assembly consists of the surgical drill guide section  400  and the interlocking base  200 . Collectively, the drill guide section  400  and base  200  can be snapped together and strategically placed relative to the lower jaw  101  which, in this instance, is a physical diagnostic anatomical model of a lower jaw for a human being. The base  200  has a base member  203  at a rearward portion, a first outwardly extending clasping or stabilizing arm  207 , and a second arm  206  that extends from the base member  203 . The arms have flattened portions and are resilient for placing a force on a jaw. The base  200  is operable to be received on the lower jaw  101  and located relative to the interior  250  and exterior  252  surfaces of the lower jaw  101 . In particular, the base  200  further has lateral contacts  202  at internal locations, which are strategically located to impinge upon exterior surface  252  of the lower jaw  101 . For example, lateral contact  202   a  is operable to impinge upon exterior contact  252   a . Likewise, lateral contact  202   b  is designed to strategically impinge upon contact surface  252   b  in two locations relative to the exterior surface  252  of the lower jaw  101 . Likewise, lateral contact  202   c  is located on an outwardly extending portion of the base frame  200 , and is operable to engage interior surface  250   c  of the lower jaw  101 . These contact points, and others, are designed to impinge forces  20  (See  FIGS. 2A ,  2 E and  6 C) for aiding and positioning, the base frame  200  relative to the lower jaw  101 . 
         [0066]    Once the base frame  200  has been positioned relative to the lower jaw  101 , the surgical drill guide section of  400  has receptacles that are snapped to interlocking connectors  204  that, in the exemplary model, are positioned at three locations about the base frame  200 . It will be appreciated that more, or fewer, interlocking connectors  204  can be provided. The locking fit between the interlocking connectors  204  and the corresponding female receptacles that are on the underneath side of the surgical drill guide section  400 , create a snap-fit type connection. This snap-fit configuration provides for ease of separability of the drill guide section  400  and the base frame  200 , as well as provides a self-centering locating arrangement for making sure the assembly  401  is properly fit together. The drill guide section  400  includes a flattened center potion  303  that has a plurality of bushings  309   a  or  309   b  extending through the flattened portion. The drill guide section  400  further may have water escape holes  304 , along with the open face drill guide bushings  309   b , as well as a separation feature or openings  601  at three locations, which aid in separating the drill guide section  400  and the base frame  200 . The openings  601  are sufficient to allow a device, for example a dental instrument, to be inserted between the drill guide section  400  and the base frame  200 , so as to allow ease of separation of the two components. 
         [0067]    The open face drill guide bushings  309   b  provide a guide mechanism for receiving positioning pins  308 . The bushings are preferably made of metal and they are anchored in the guide section  400 . The positioning pins  308  may be made of metal or hard plastic and are placed into the planned osteotomies within the lower jaw anatomical diagnostic model  101  and are configured to receive the bushings  309   b , which helps align the drill guide  400  relative to the jaw  101 . At the surgery, drill guide bushings guide the drills to create osteotomies for implant placement. 
         [0068]      FIG. 9  illustrates another exemplary drill guide assembly  401  including a drill guide section  400  and a base frame  204   b , which also works as a bone reduction jig. The assembly  401  can be positioned relative to exposed bone area  104   b  of a lower jaw  101 , which, in this visual, is a diagnostic anatomical lower jaw model. This particular lower jaw model  101  includes extracted teeth sockets  110 , which can be either recently extracted teeth or digitally simulated planned teeth extraction, a gum tissue area  102 , and nerve endings  112 . The base frame  200   b  has interlocking connectors  204  formed on the upper surface of the base frame  200   b  that can be integrally molded to the base frame  200   b . Lateral contacts  202   a  and  202   b  are positioned about an interior surface of the clasping arm  207  and form pressure points for impinging upon exterior surface  252  of the lower jaw  101  at points  252   a , and  252   c , respectively. 
         [0069]    The surgical drill guide section  400  is shown ready to be positioned and connected to the base frame  200   b . Drill guide bushings  309   a  are provided within holes for receiving positioning pins  308 . An opening  601  is provided to help in separating the drill guide section  400  from the base frame  200   b.    
         [0070]      FIG. 10  illustrates the  FIG. 9  surgical drill guide assembly  401  in an assembled condition. The drill guide  400  is shown in place relative to the base frame  200   b  which in turn, is positioned relative to the lower jaw  101 . 
         [0071]      FIG. 11  illustrates a bottom perspective view of the  FIG. 6  surgical drill guide assembly  401 . From this perspective, the underside of the base frame  200  and the drill guide section  400  can be more readily observed. The lower jaw  101  is shown with gum tissue  102 . The Base frame  200  has scalloped or saddle shaped tissue contact portions  220  that are received by the gum tissue areas  102  of the lower jaw  101 . The clasping arm  207  has impinging areas  202   a  and  202   b  that impinge upon surfaces  252   a  and  252   b , respectively, of the jaw  101 . Likewise, impinging surface  202   c  impinges upon corresponding internal surface  250   c  of the jaw  101  so as to provide an inwardly impinging force  20  as previously depicted in  FIG. 6C . 
         [0072]    The surgical drill guide section  400  has receptacles on the underside surface  452  that are operable to lockingly engage with interlocking connectors  204  ( FIG. 9 ) of the base frame  200 . Openings  601  provide a gap between the surgical drill guide  400  and the base frame  200  so as to allow for ease of separation between these two components. The recess  450  is slightly larger in physical configuration than the interlocking connector  204 . The interlocking connector  204  is sufficiently resilient, as is the receptacle  450 , so as to provide a positive snap-fit locking configuration between the components  400  and  200 . Once together, an interlocked assembly  401  is created, which can be easily aligned relative to the jaw  101 . 
         [0073]      FIG. 12  illustrates a perspective view of the base frame  200 , which is functioning here as a bone reduction jig, being positioned relative to the lower jaw  101  in the context of a mouth  150 . It depicts the lower jawbone having a shaved section  152  according to the clasping arm portion of the base frame  200 . Extracted teeth sockets  154  are present and depict the location of the extracted teeth. An interlocking connector  204  is shown and is operable and ready to receive the surgical drill guide section  400  (not shown). 
         [0074]      FIG. 13  and  FIG. 14  show different manufacturing methods of using an edentulous surgical drill guide or assembly  401 .  FIG. 13  illustrates a model based implant placement planning method  800  and  FIG. 9  illustrates a digital implant placement planning method  900 . Both methods start with a digital anatomical diagnostic model, with partially exposed jawbone  101  in the area of interest, in a file format such as STL that allows reverse engineering and 3D modeling  801  and  901 . The digital anatomical diagnostic model  801  can be obtained by accurately aligning the surface scan data of the patient&#39;s mouth or dental cast and the tomography scan data that is volume rendered and converted to a compatible file format. Since all the devices are patient specific, the design and features of the apparatus is planned according to the patient&#39;s oral structure, bone condition, and the surgical needs. Although the apparatus can be created as one single surgical guide as described in the diagram in  FIG. 7 , the same or similar procedure may be applied when using a multiple piece guide. 
         [0075]    In both methods, a technician digitally designs the base frame  200 , and the drill guide housing frame  300 , along with additional frames and attachments, if any, using reverse engineering software program such as Geomagic, Radidform, and 3 Matics, optionally combined with 3D modeling software such as Rhinoceros 3D and Solidworks (See steps  802 ,  902 ,  803  and  903 ). The base frame  200  ( FIG. 2 ) can be designed first on the digital model with partially exposed bone just in the area of the surgical site  802  and  903  and then the drill guide housing frame section  300  ( FIG. 3 ) can be designed on both the digital anatomical diagnostic model and the base frame ( 802  and  902 ). By doing so, the surgical guide can be designed to obtain better fit and stability, because 1) it avoids bone contact in the areas where the density of the bone is too close to that of the soft tissue for its contour to be accurately defined in the CT images when the bone is porous, and 2) it also clasps onto rigid bone areas instead of contacting the malleable tissue surface alone. Subsequently, if additional frames or attachments are needed, they can be designed to fit on the base frame  200  and/or the surgical drill guide housing frame  300  according to the part&#39;s function  803  and  903 . Some of the features and functions of the apparatus are the same or similar for the model based implant placement planning or the digital implant placement planning. However, several differences may be found in features and methods between for these two situations. 
         [0076]      FIG. 13  illustrates a workflow  800  of a model based surgical planning. When the implant placement is planned on an aligned physical anatomical diagnostic model  812  created by rapid prototyping  811  the digital model  801 , the technician needs to design the drill guide housing frame or housing frame section  300  on the digital anatomical diagnostic model without knowing the exact plan of implants&#39; positioning. Naturally, the device is designed as a base structure of the surgical guide that will be assembled manually on the physical anatomical model. Thus, the device often has the skirted area  301  ( FIG. 3B ) that extends over the intended site so that it is easier for the clinician or technician to assemble the surgical drill guide later on a physical anatomical diagnostic model (See steps  806 - 809 ). Similarly, other special parts that work on the physical model may also be designed to aid the surgical guide assembly. Meanwhile, a physical anatomical diagnostic model is manufactured by rapid prototyping or CNC milling (See steps  811 - 812 ), and ideal osteotomies are simulated on the physical anatomical diagnostic model by a qualified clinician (Step  813 ). Alternatively, the modified anatomical diagnostic model with positioning pins placed into the osteotomies can be digitized by surface scanning (Step  814 ), and the drill guide  200 ,  400  or  700  may be designed on the modified digital anatomical diagnostic model. If bone reduction is planned on a physical anatomical diagnostic model then the doctor can drill the ideal osteotomies into the physical model, (See step  813   b ). 
         [0077]    After all the parts are designed on the digital diagnostic model, they are manufactured by rapid prototyping such as 3D printing and stereolithography or CNC milling  804 , cleaned, inspected, and verified on the physical anatomical model  805 . Place the base frame and the drill guide housing frame  200  on the physical anatomical model  100 , as shown in step  806 . 
         [0078]    If the drill guide housing frame has skirted areas  301  ( FIG. 3B ) over the surgical site, drill holes may be placed through the skirted areas  301  with a hand piece  306  ( FIG. 3C ) so that the holes correspond with the planned osteotomies. Since the drill guide housing frame is usually made with a transparent or semi-transparent material, the simulated osteotomies on the model is visible thorough the thin skirted areas  301 , and corresponding holes can be made. Positioning pins  308  may be inserted into the osteotomies on the anatomical model through the holes of the skirted areas  808 . Drill guide bushings  309  may be placed with respect to the positioning pins  308  and the bushings&#39; distance may be set from the oral structure according to the preference. As briefly described above, the top or the bottom of the skirted areas  301  may be set at, below or above the gum tissue surface  102 . 
         [0079]    Alternatively, the bottom of the skirted areas  301  may be made to contact the exposed bone. If the diameter of holes on the skirt is close to the inner diameter of the drill guide bushing, the bushing can rest on the skirted areas. The holes of the skirted areas  301  may also be made larger so that extra parts to control the height can be inserted onto the positioning pins  305 . It should also be noted that the drill guide housing frame  300  may be configured to accommodate various types of interchangeable drill guide bushings as well as most of depth control surgical guide system parts sold by various implant companies. After the positions are set, the bushings maybe attached to the drill guide housing frame with light cured composite or other adhesive materials  809 . Additional light cured composite may be added to the frame to increase the rigidity of the device. Light cured composite may be added around the positioning pins on the skirted areas  301  instead of bushings to conform drill guide holes or slots. When finished, the positioning pins may be removed from the physical anatomical model  810 . The skirted area can be then trimmed by a hand piece as previously described. Additional drill guide frames, if any, can be made by repeating the process. With a model based implant placement system, it may also be possible to manually create a surgical drill guide that clasps the gum tissue and the jawbone with similar features without any digitally designed frame structures. It should be noted that the skirted area may not be necessary if the anatomical diagnostic model is surface scanned after the doctor drills the osteotomies, and the apparatus is designed on the modified digital model. 
         [0080]      FIG. 14  illustrates a flowchart of digital surgical planning. When the implant placement is planned digitally on an aligned digital anatomical diagnostic model  902  as illustrated in  FIG. 14 , the creation of physical anatomical diagnostic model may be optional. In this case, the technician can design the drill guide housing frame according to the simulated osteotomies on the digital anatomical model. Thus, there may be no need to create any skirted area. The support structure and receptor sites for the drill guide bushings can be digitally designed  903  so that the device is ready to receive the parts after prototyping. If any drill guide bushing parts with depth control function are going to be used, the device can be designed to receive those parts at the exact locations to accommodate the function. If the jaw bone  101  is reduced on the digital anatomical diagnostic model, the base frame  200  may be designed to function as a bone reduction jig. 
         [0081]    Similar to the method for a model based implant placement system, the drill guide housing frame  300  is manufactured, along with the base frame and other additional frames and accessories, by rapid prototyping or CNC milling  905 . After cleaning and inspection  906 , the preferred drill guide bushings  309  can be placed into the drill guide frame  300  and secured by light cured composite or other adhesive material. For some type of drill guide bushings ( 309 ) adhesives may not be needed. The drill guide may also be created with built-in drill guide holes or slots without any separate parts if the device is made of an appropriate harder material such as metal. 
         [0082]      FIG. 15  illustrates a flowchart of how the apparatus  401  can be utilized  1000  during an implant placement surgery. It will be appreciated that the steps can be modified, yet remain within the spirit of the exemplary embodiments herein. It should be noted that there are many variations to the workflow, and this chart is not intended to teach the surgical procedure itself. As is the case with the explanation of diagrams in  FIG. 13  and  FIG. 14 , the following explanation is directed to a multiple piece drill guide system  401 . 
         [0083]    Prior to the surgery, all the parts of the drill guide set  401  are properly sanitized according to the material&#39;s requirement. For example, if the parts are rapid prototyped with resin, cold sterilization methods may be appropriate. However, heat sterilization may be used for different materials with high temperature tolerance  1001 . Lay a partial flap of the patient&#39;s gum tissue to expose the jawbone in the area of interest  1002 . In rare occasions, the surgeon may choose to flap only the areas that the bone clasping contact portions of the devise will contact with, leaving the gum tissue over the implant sites. The base frame  200  or the single piece surgical drill guide  300  may be securely placed on the oral structure  100  and in contact with both gum tissue and the exposed bone (See steps  1003  and  1003   b ). Additional attachments may be added to the device for bone clasping. Depending on the patient&#39;s oral structure, anchor screws or pins may be used for securing the position of the device. Bone adjustment or bone grafting may be done before or after the placement of the base frame  200 . If the bone adjustment is needed, the base frame may be used as a jig or an additional bone adjustment jig can be attached to the base frame  200  for this process. 
         [0084]    Optionally, a modified denture duplicate attachment  500  ( FIG. 5 ) can be used on the base frame  200 . In that case, verify the device&#39;s poisoning with bite to secure the base frame  200  to the oral structure, and then remove the attachment portion, leaving the base frame  300  on the oral structure  1009  and  1010 . 
         [0085]    After the base frame is securely placed, attach the drill guide section  300  to the base frame  200  (step  1004 ) in order to drill osteotomies into the jawbone (step  1005 ). The interchangeable additional drill guide sections may be used to complete the osteotomies  1011 . When finished, the drill guide section  400  may be removed from the base frame ( 200 ), and the implants may be placed into the jawbone (see step  1006 ). Should a certain type of surgical guide tube system be adopted into the drill guide frame  300 , the surgeon may place the implants through the drill guide tube bushings  1009  prior to the removal of the drill guide section  400 . 
         [0086]    The surgeon may choose to take a fixture level index for the record of implant positions at this point. In that case, he/she may be able to do so by altering the surgical guide section  400  into a transfer jig tray or by using a separate transfer jig tray that attaches to the base frame  200  (See step  1012 ). One advantage of utilizing the drill guide section  400  is that the actual positioning information can be easily transferred back to the physical anatomical model. The model can be adjusted, if necessary, and the prosthesis can be created on it without making a separate brand new model. 
         [0087]    After the base frame is removed  1007  the surgeon can complete the surgery by placing cover screws or healing caps, and suturing the gum tissue over the cover screw or around the healing caps. Alternatively, the immediate loading procedure may be followed, and the prosthesis that had been designed on the digital or the physical anatomical model can be placed  1008 .