PATENT ABSTRACT
The present invention provides an inexpensive surgical guide preparation tool by which an insertion hole for implant can be correctly and easily formed at a predetermined position. 
     The surgical guide preparation tool has a pair of marker members opposing to each other and a gauge body which has a support member for connecting the marker members, and the gauge body is attached to a surgical guide body. The surface of each marker member is provided with grid-like lines which are recognizable by a CT scanned image and disposed longitudinally and laterally at substantially regular intervals; predetermined marks are chosen from intersections of the grid-like lines, and a guide ring is attached to the surgical guide body so that a direction connecting the chosen marks is used as an axial direction of the guide ring. The axial direction of the guide ring is used as an insertion direction for implant.

PATENT DESCRIPTION
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a surgical guide preparation tool for placing a dentistry implant at a predetermined position, and a method for preparing a surgical guide. 
       BACKGROUND INFORMATION 
       [0002]    In recent years, dentistry treatments to form a denture by embedding an implant (artificial tooth root) in a tooth deficient portion have been performed. In such treatments, insertion holes for implant are drilled at tooth deficient portions by use of a drill attached to a drilling apparatus such as a handpiece, and at this time, a surgical guide is usually employed to drill a hole in order to guide the drill so that the hole for implant would be formed at a predetermined position and in a predetermined direction. 
         [0003]    Into this surgical guide, a metallic guide ring (guide tube) is fitted to guide the drill to the surgical guide supported by jawbone, etc. 
         [0004]    When the guide ring is employed to guide the drill for drilling a hole, it is required that adequate bone quantity is confirmed at the portion where the hole for implant is formed and no nerves or blood vessels are present at this portion. 
         [0005]    In order to satisfy such requirements, in usual, a CT scanning is conducted by use of an X-ray CT apparatus (Computed Tomography) in such a state that a surgical guide (a stent for diagnosis) is attached to the teeth of patient, and the examination results by the CT, scanned image is used to determine the insertion direction of the implant. 
         [0006]    Various methods have been proposed as a method for determining the insertion direction of implant. 
         [0007]    For example, European Patent No. 1043960 describes a method for processing a hole for implant by a numerically controlled boring machine which moves in relation with an X-ray CT apparatus. 
         [0008]    In this method, since the numerically controlled boring machine is additionally employed, the entire machine becomes large, the operation requires skillfulness and costs become high. 
         [0009]    Further, as described in JP-A-2006-141561, a method has been proposed in that the CT scanned image of a jaw bone area of tooth deficient portion is printed, the tooth deficient portion is cut out from the print, the cutout part is adhered to a teeth impression model, and then the adhered cutout part is given a mark showing the insertion position and direction of implant, and a hole for implant is drilled along this mark. 
         [0010]    However, in this method, many operations are required as described above and the hole for implant is processed while visually observing the mark, whereby there is a concern that the hole for implant may not be processed correctly. 
       PRIOR ART DOCUMENTS 
     Patent Documents 
       [0000]    
       
         Patent document 1: European Patent No. 1043960 
         Patent document 2: JP-A-2006-141561 
       
     
       DISCLOSURE OF THE INVENTION 
     Problems that the Invention is to Solve 
       [0013]    The present invention is to solve such problems and provide a surgical guide preparation tool and a method for preparing the surgical guide, whereby a hole for implant can be formed at a predetermined position correctly and easily. 
       Means of Solving the Problems 
       [0014]    The present invention provides a gauge body having a pair of marker members each of which has plural marks which are recognizable by a CT scanned image and disposed longitudinally and laterally at substantially regular intervals. Using a surgical guide preparation tool comprising the gauge body attached to a surgical guide body, predetermined marks are chosen from the plural marks on the marker members, and the direction connecting the chosen marks is used as the direction of the hole for implant. To the marker members, a support member for supporting the marker member is provided. 
         [0015]    Further, in the present invention, it is possible to detachably install an X-ray impermeable artificial tooth which can be recognized by a CT scanned image at the internal side of the gauge body, and confirm the positional relation between the direction of the hole for implant and the artificial tooth. 
         [0016]    Furthermore, the method for preparing a surgical guide of the present invention comprises a step of preparing the above gauge body; a step of installing the gauge body at a position of the surgical guide body that corresponds to a deficient tooth, capturing into a computer a CT scanned image obtained in such a state that the surgical guide body is positioned on the teeth, and reading the positions of marks of both marker members corresponding to the insertion direction of the implant by analysis with computer operation; a step of inserting a positioner into the internal side of the guide ring, inserting the guide ring into the internal side of the gauge body, and inserting a pin in such a direction connecting the axis of the positioner and the position of the marks of respective marker members from which the insertion direction of the implant has been read; a step of fixing the guide ring to the surgical guide body at such position where the pin is inserted, and then removing the pin, positioner and gauge body. 
         [0017]    In addition to the above steps, the method for preparing a surgical guide of the present invention further comprises a step of detachably installing the X-ray impermeable artificial tooth which can be recognized by a CT scanned image at the internal side of the gauge body, and removing the artificial tooth when the guide ring is inserted into the internal side of the gauge body; and a step of forming a slit on the guide ring so that a blade portion of a drill for boring a jaw bone can be inserted from the side face of the guide ring, and forming an opening portion of which the width is substantially the same as the slit or expands outwardly and more widely than the slit at a position of the surgical guide body corresponding to the slit. 
         [0018]    The surgical guide is a support having a guide ring, and this is classified into a type supported by jaw bone, a type supported by gum, and a type supported by teeth. All of the surgical guides of these types are generally made of a plastic material. If the surgical guide is made of a transparent material, the operation site can be easily seen. 
         [0019]    The guide ring to be installed in the surgical guide is made of a metal such as titanium or aluminum or a hard plastic material, with an inner diameter of about 4 mm to 9 mm and an outer diameter of about 5 mm to 10 mm so that it will suit the diameter of a guide member of a drill. However, the size is not limited to these ranges. 
         [0020]    At the side face of the guide ring, a slit is formed so that the front end portion of an implant medical instrument such as a blade portion of a drill, an implant and an adaptor for inserting the implant can be inserted from its sidewise direction. At a position of the surgical guide body corresponding to the slit, the surgical guide body is provided with an opening portion of which the width is substantially the same as the slit or expands outwardly and more widely than the slit. 
         [0021]    Since the diameter of the blade portion of the drill is generally about 2 mm to 5 mm to suit to the diameter of the implant, the width of the slit is about 4 mm to 6 mm which is a little larger than the maximum diameter of the implant to be used. However, the width of the slit is not limited to this range. 
         [0022]    If the upper part of the guide ring is outwardly expended in a tapered shape, the drill can be easily guided. 
         [0023]    The gauge body is installed in the surgical guide body. The gauge body has a pair of marker members opposing to each other, and the marker members may have a surface configuration of quadrilateral, rectangular, circular, elliptical, trapezoidal, etc. As the size of the gauge body, when it is used for one tooth deficient portion, the lengthwise and lateral widths are about 10 to 20 mm, the height is about 10 to 30 mm, and the thickness is about 1 to 2 mm. However, the size is not limited to these ranges. When it is used for adjoining plural teeth deficient portion, the width is of course adjusted suitably to the number of teeth. 
         [0024]    The surfaces of the pair of marker members of the gauge body are provided with marks which are recognizable by a CT scanned image and disposed longitudinally and laterally at substantially regular intervals. The marks may be provided on the side faces of the marker members. 
         [0025]    When the pair of marker members is made of an X-ray permeable member, for example, an X-ray permeable plastic material, grid-like lines or grooves are formed by coating the marker member surfaces with an X-ray impermeable material (e.g. barium sulfate, bismuth oxide, bismuth subcarbonate, etc.) and intersections of these lines or grooves are used as marks, or an X-ray impermeable material is embedded in grid-like or dot-like form on the marker member surface and the intersections of the grid or the dots are used as marks. In this instance, when a pigment, a coating, etc. is blended to the X-ray impermeable material for coloration, the marks can be further easily seen. 
         [0026]    The intersection portions may be provided with small holes, and a part of the small holes (a hole located at the center of the marker member, or a hole located at the end thereof) may be formed larger than others and used as a standard hole. The size of the small holes is about 1 mm in diameter, but may be of other diameter. 
         [0027]    On the other hand, when the pair of marker members is made of an X-ray impermeable material, for example, a metallic material or a plastic material having an X-ray impermeable material blended, small holes or standard holes are disposed at the positions as the intersections of grid-like lines, and such small holes are used as marks. In this instance, it is advisable that grid-like lines are given on the surfaces of the pair of marker members so that the grid-like lines can be visually observed. 
         [0028]    The position of mark is not limited to just on the grid-like lines, and it may be located at the intersections of appropriately shaped-lines such as a spider web-like or ripple-like shape so far as the position can be recognized by a CT scanned image. Further, a metallic mesh material may be used as the marker member, and in this instance, the holes of the mesh are used as the position of mark. 
         [0029]    The marks are formed at intervals of about 1 to 2 mm, but may have other intervals. Further, the marks are formed to have a depth of about 0.5 to 1 mm, but may have other depth. 
         [0030]    Since the internal side of the gauge body is space, the artificial tooth corresponding to the tooth deficient portion can be inserted into this space. The artificial tooth is temporarily fixed to the lower marker member, a support member, etc. of the gauge body, with a polymerizable resin, etc. Further, the surface of the artificial tooth is recognizable by the CT scanned image by coating the surface with an X-ray impermeable material or producing the artificial tooth integrally with an X-ray impermeable material. By installing the artificial tooth within the internal side of the gauge body, it is possible to observe the occluded condition of teeth in the insertion direction of implant and install the artificial tooth at the predetermined position and in the predetermined direction. The artificial tooth may sometimes be omitted. 
         [0031]    A surgical guide preparation tool comprising a surgical guide body and a gauge body attached thereto or a surgical guide preparation tool comprising a surgical guide body and a gauge body with the artificial tooth, attached thereto, is installed in a portion corresponding to the patient&#39;s deficient tooth, and subjected to CT scanning with an X-ray CT scanning machine to obtain a CT scanned image. This CT scanned image is captured into a computer, and analyzed by use of a CT scanned image analyzing software (for example, a software such as One Volume Viewer: J. MORITA MFG. CORP.), and while confirming the marks of respective marker members of the gauge body and the position of the artificial tooth, the position of mark corresponding to the insertion position and direction of implant is determined. The above CT scanned image may be at first stored in a recording medium such as CD or DVD and then captured into a computer; or the X-ray CT scanning machine may be connected to a computer, and the CT scanned image may be directly captured into the computer. 
         [0032]    After the CT scanning, the surgical guide preparation tool is removed from the patient, a pin made of a metal such as stainless steel or a tough plastic is inserted into a small hole as the mark of each marker member determined as above. If no small hole is formed, a small hole may be perforated by a pointed pin. The direction of this pin is used as the predetermined insertion direction of implant. 
         [0033]    Here, the pin is temporarily pulled out, a positioner is inserted into the guide ring, this guide ring is inserted into the internal space of the gauge body, and the pin is again inserted into the small hole as the mark and the hole at the center of the positioner. Under this condition, a fixing material such as a polymerizable resin is filled around the guide ring to fix the guide ring to the surgical guide body. 
         [0034]    After the fixing material is cured, the pin is removed, and then the gauge body and the positioner are removed to complete the surgical guide. The positioner is usually made of a plastic material (including a foamed material), but may be made of other materials. 
       Effects of the Invention 
       [0035]    In the present invention, as described above, it is possible to correctly match the position and direction of the guide ring attached to the surgical guide with the insertion position and direction of the implant, and therefore the precision of implant treatment can be increased and costs can be reduced. Further, by using the preparation tool and preparation method of the present invention, it becomes possible to improve the safety in implant operation and shorten the operation time, whereby the mental burden of the patients, operators and medical staff can be reduced, treatment results can be improved, and the economic burden on patients and clinics can be reduced. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]      FIG. 1  is a perspective view of a surgical guide showing an example of the present invention. 
           [0037]      FIG. 2  is a perspective view of a surgical guide preparation tool. 
           [0038]      FIG. 3  is a perspective view of a lower jaw teeth impression model. 
           [0039]      FIG. 4  is a perspective view of a surgical guide body. 
           [0040]      FIG. 5  is a perspective view of a gauge body. 
           [0041]      FIG. 6  is a perspective view showing a state where a surgical guide preparation tool is attached to a lower jaw teeth impression model. 
           [0042]      FIG. 7  is a schematic view showing a CT scanned image taken when a surgical guide preparation tool is attached to the patient&#39;s teeth. 
           [0043]      FIG. 8  is a perspective view showing a state where a guide ring is inserted into the internal space of a gauge body. 
           [0044]      FIG. 9  is an enlarged perspective view of a positioner. 
           [0045]      FIG. 10  is an enlarged perspective view of a guide ring. 
           [0046]      FIG. 11  is an exploded perspective view of an assembled gauge body showing another example. 
           [0047]      FIG. 12  is an exploded perspective view of an assembled gauge body showing a further example. 
           [0048]      FIG. 13  is an exploded perspective view of a gauge body showing another example. 
           [0049]      FIG. 14  is a perspective view of a drill. 
           [0050]      FIG. 15  is a schematic view of a computer system for analysis of a CT scanned image. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0051]    Hereinafter, the surgical guide preparation tool and the method for preparing the surgical guide will be explained. 
         [0052]    A surgical guide  1  shown in  FIG. 1  has a guide ring  4  which guides a guide member  3  of a drill  2  shown in  FIG. 14 . This guide ring  4  is attached to a surgical guide body  6  so that the installed position and direction of the guide ring would match the insertion position and direction of an implant. The attachment is carried out by a surgical guide preparation tool  7  comprising surgical guide body  6  (shown in  FIG. 4 .) and a gauge body  5  (shown in  FIG. 2 ) attached thereto, as shown below. 
         [0053]    As shown in  FIG. 3 , firstly, a patient&#39;s lower jaw teeth impression model  8  and an artificial tooth  9  which corresponds to a deficient tooth are prepared; and a pin  10  is put into a hole  68  of the lower jaw teeth impression model  8  which is presumed to be bored at an appropriate position and in an appropriate direction, through a center hole  67  of the artificial tooth  9 , and then the artificial tooth  9  is temporarily fixed to the lower jaw teeth impression model  8 . The surface of the artificial tooth  9  is coated with an X-ray impermeable material. 
         [0054]    Then, the surgical guide body  6  is prepared by using the lower jaw teeth impression model  8 . At a portion of the surgical guide body  6  which corresponds to the deficient tooth, a hole  11  is formed so that a part of the upper portion of the artificial tooth  9  would be exposed as shown in  FIG. 4 . 
         [0055]    As shown in  FIG. 5 , the gauge body  5  comprises an upper marker member  12 , a lower marker member  13  and a support member  14  which connects the pair of marker members. The gauge body  5  is generally prepared integrally with a plastic material having X-ray impermeability. 
         [0056]    The surfaces of the marker members  12 ,  13  are given grid-like lines  15 , and at the intersections of the lines, small holes  16  are bored. A hole at the center portion of the marker member is formed to have a larger diameter than that of small holes  16  and is used as a standard hole  17 . 
         [0057]    Here, as shown in  FIG. 6 , the artificial tooth  9  and pin  10  are removed from the lower jaw teeth impression model  8 , and the artificial tooth  9  is inserted into an internal space  18  of the gauge body  5  and placed on the lower marker member  13 . And, the position of the gauge body  5  is determined by putting a pin  35  through the standard hole  17  of the gauge body  5 , a hole  67  at the center of the artificial tooth and a hole  68  of the lower jaw teeth impression model  8 . When the support member  14  of the gauge body  5  abuts on the side face of the surgical guide body  6 , a part of the side face portion of the surgical guide body  6  is removed. 
         [0058]    In this instance, in order to allow the lower marker member  13  of the gauge body  5  to be inserted into the lower side of the surgical guide body  6 , the lower portion of the artificial tooth  9  is preliminarily removed in such a thickness corresponding to the thickness of the lower marker member  13  to adjust the installation height of the artificial tooth  9 , and then the artificial tooth  9  is temporarily fixed at a predetermined position by use of a polymerizable resin, an adhesive, etc. Thereafter, the surgical guide body  6  and the gauge body  5  are fixed with fixing material  38  such as a polymerizable resin, and then the pin  35  is pulled out to complete the surgical guide preparation tool  7 . 
         [0059]    The thus prepared surgical guide preparation tool  7  is attached to the patient&#39;s teeth, and a CT scanned image  20  is obtained by CT scanning with an X-ray CT scanning machine  19 . 
         [0060]    As shown in  FIG. 15 , the CT scanned image  20  is captured into a computer  21  (provided with a monitor  22 , a key board  23  and a mouse  24 ), the image is analyzed with use of a CT scanned image analyzing software installed in the computer  21 , and the positions of marks of the pair of marker members  12 ,  13  which correspond to the insertion direction of implant are recognized. 
         [0061]    Namely, as shown in  FIG. 7 , an axial section  25 , a panorama section  26  and an orthoradial section  27  are displayed by operation of the computer  21 , and while confirming the positions of respective marker members of the gauge body, a panorama cutting line  29  and an orthoradial cutting line  30  are moved on these sections in such a direction that the implant is to be inserted. After confirming that sufficient jaw bone is present in the directions of the panorama cutting line  29  and the orthoradial cutting line  30  on the panorama section  26  and the orthoradial section  27  and further confirming that nerves and blood vessels  31 ,  32  are not present at these sites, these directions are determined to be an insertion direction of implant. 
         [0062]    In the determined direction, by moving an axial cutting line  28 , marks  33 ,  34  of respective marker members positioned at the intersections of the above cutting lines are read as marks corresponding to the insertion direction of implant. At this instance, the positions of the marks  33 ,  34  can be determined by reading the distance of the small holes or scale on the CT scanned image from the standard hole  17 . 
         [0063]    Next, as shown in  FIG. 8 , a part of the surgical guide preparation tool  7  is removed and the artificial tooth  9  is taken out, and then the pin  35  is inserted into two holes formed at the marks  33 ,  34  of respective marker members which have been read. Before the pin is inserted, a positioner  36  shown in  FIG. 9  is inserted into the guide ring  4  shown in  FIG. 10 , and this guide ring  4  is inserted into the internal space  18  of the gauge body  5 . And, the pin  35  is put into a hole  37  at the center of the positioner  36 . At both or either one of edge faces of the positioner  36 , a funnel-shaped convex face  69  is formed, and the front end part of the pin  35  can be guided with the convex face  69  and can be easily inserted into the hole  37  at the center of the positioner  36 . 
         [0064]    Under such condition, a fixing material  38  such as a polymerizable resin is filled around the guide ring  4 , and the guide ring  4  is connected to the surgical guide body  6  to integrate them. Thereafter, the pin  35 , positioner  36  and gauge body  5  are removed to complete the surgical guide  1  as shown in  FIG. 1 . After removing the gauge body  5 , etc., if necessary, a fixing material such as a polymerizable resin may be supplied to a connecting portion of the guide ring  4  and the surgical guide body  6 . 
         [0065]    Around the guide ring  4 , a convex  39  or concave is formed, by which rotating motion of the guide ring  4  can be prevented. 
         [0066]    The surgical guide  1  is provided with an opening portion  41  expanding outwardly so that it would have a width larger than the width of a slit  40  of the guide ring as shown in  FIG. 1 . The width of the slit  40  is at such a level of allowing a blade portion  59  for dentistry to pass therethrough as shown in  FIG. 14 , and the inner diameter of the guide ring is at such a level of allowing the guide member  3  of the drill  2  to be slidably guided. 
         [0067]    The gauge body  5  shown in  FIG. 11  is of an assembly type, and comprises an upper member  42  having an upper marker member  12  and a support member  14  integrally formed, a lower marker member  13  provided with a support plate  43 , and a base plate  44  for supporting the artificial tooth  9 . A support frame  45  extends from the lower end portion of the upper member  42 , and this support frame  45  engages in a dovetail groove  47  formed by a projection  46  disposed on the lower marker member  13 . Further, the base plate  44  engages in a dovetail groove  48  formed by the projection  46  disposed on the lower marker member  13 . On the surfaces of the upper marker member  12  and lower marker member  13 , marks  49  drawn in grid-like form with an X-ray impermeable material are indicated. In this example, a base plate  44  is disposed. However, in a case where the artificial tooth  9  is directly supported by the lower marker member  13 , the base plate  44  is omitted. 
         [0068]    The gauge body  5  shown in  FIG. 12  shows another assembly type, and comprises an upper marker member  12 ; an upper frame member  52  having an upper frame  50  supporting the upper marker member  12 , and one support member  51 , integrally constituted; a lower marker member  13 ; a lower frame member  55  having a lower frame  53  supporting the lower marker member  13 , and another support member  54 , integrally constituted; and the artificial tooth  9 . The upper marker member  12  engages in a dovetail groove  60  disposed on the upper frame  50 , and the lower marker member  13  engages in a dovetail groove  61  disposed on the lower frame member  55 . Another support member  51  for the upper frame member  52  and another support member  54  for the lower frame member  55  are connected by engaging a concave-type projection  56  and a convex-type groove  57  formed on these support members, respectively. In this example, the upper frame member  52  and the lower frame member  55  are made of a transparent material; the positions of marks  58  obtained by analysis of a CT scanned image are indicated on the upper frame  50  and the lower frame  53 ; and the upper frame member  52  and the lower frame member  55  are used as expendable supplies, and the upper marker member  12  and the lower marker member  13  are reused as master pieces. 
         [0069]    The gauge body  5  shown in  FIG. 13  comprises the upper marker member  12 ; an upper frame  63  which has a support portion  62  and supports the upper marker member  12 ; a lower marker member  13 ; a lower frame  64  which supports the lower marker member  13 ; and the artificial tooth  9 . The upper marker member  12  engages in a dovetail groove  65  disposed on the support portion  62  of the upper frame  63 , and the lower marker member  13  engages in a dovetail groove  61  disposed on the lower frame  64 . 
       EXPLANATION OF NUMERALS 
       [0000]    
       
           1  Surgical guide 
           4  Guide ring 
           5  Gauge body 
           6  Surgical guide body 
           8  Lower jaw teeth impression model 
           9  Artificial tooth 
           12  Upper marker member 
           13  Lower marker member 
           14  Support member 
           16  Small hole 
           17  Standard hole 
           19  X-ray CT scanning machine 
           20  CT scanned image 
           21  Computer 
           33 ,  34 ,  49 ,  58  Marks 
           35  Pin 
           36  Positioner 
           40  Slit 
           41  Opening portion