JP2011036597A - Bone absorbed dose measuring program after dental implant surgery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately evaluate a three-dimensional bone absorbed dose of the whole periphery of an implant in a noninvasive manner. <P>SOLUTION: A computer carries out an after-surgery image input step S101 for inputting a three-dimensional image around an affected part including the implant after a dental implant surgery; a diagnosis object image input step S102 for inputting a three-dimensional image after the lapse of an optional time around the affected part including the implant; volume computing steps S104-S110 for computing bone volume concerning implant embedding in a predetermined space based on an implant axis with respect to the three-dimensional image around the affected part including the implant; and bone absorbed dose computing steps S113, S114 for computing volume in the volume computing steps S104-S110 for each of the three-dimensional images input in the after-surgery image input step S101 and the diagnosis object image input step S102 to compute the bone absorbed dose from two computed volumes. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a bone resorption measurement program after dental implant surgery.

  One of the criteria for the success of dental implants that was consensus at the Toronto Conference in 1998 is that the average annual vertical bone resorption after the first year of functioning is less than 0.2 mm. There is an item.

If treatment at the time of implanting a dental implant is not properly performed, bone resorption occurs in the alveolar bone contacting the implant body after several years, and it becomes difficult to grasp the implant. Therefore, it is important as a preventive measure to confirm the vertical bone resorption amount of the alveolar bone in contact with the implant body according to the elapsed years. Various proposals have been made regarding this type of technology. (For example, Non-Patent Document 1 and Non-Patent Document 2)
The current methods for measuring vertical bone resorption are only two-dimensional evaluation using X-ray fluoroscopic images and measurement involving invasion with a pocket probe.
A calculation method of two-dimensional vertical bone resorption using a fluoroscopic image is performed by the following method.

  First, a post-operative two-dimensional X-ray fluoroscopic image taken under the same conditions and a two-dimensional X-ray fluoroscopic image after several years are prepared. On the image, a vertical line is drawn downward along the side of the implant body from the top of the implant, that is, the connecting portion with the abutment, and the distance to the position where the bone exists is obtained. By comparing this distance between after surgery and after several years, the reduction distance of the alveolar bone in contact with the implant body is measured.

  If the annual vertical bone resorption satisfies the standard of 0.2 [mm] or less, the implant body is determined to satisfy the success standard in the Toronto meeting and maintain a healthy state. Note that the same method is consistently applied to the same patient as a method for checking the presence or absence of bone mass using a certain measurement method.

"Comparison of Cone-Beam Imaging with Orthopantomography and Computerized Tomography for Assesment in Presurgical Implant Dentistry" Timo Dreseidler et al, P.216-P.225, The International Journal of Oral & Maxillofacial Implants, Volume 24, Number 2, 2009. "Immediate and early loading of Straumann implants with a chemically modified surfice (SLActive) in the posterior mandible and maxilla: 1-year results from aprospective multicenter study" Jeffrey Ganeles et al, P.1119-P.1128, Clin. Oral Impl. Res. 19, 2008, The Authors. Journal compilation.

  The former two-dimensional X-ray fluoroscopy method has a partial measurement range and lacks accuracy. Moreover, although the latter inspection method using the pocket probe can measure the entire circumference, there is a risk of causing bacterial infection by damaging the implant body.

  The present invention has been made in view of the above circumstances, and its object is to provide a non-invasive dental implant that can accurately evaluate the three-dimensional bone resorption amount around the entire implant. It is to provide a bone resorption measurement program after surgery.

  One aspect of the present invention is a post-operative image input step for inputting a three-dimensional image around an affected area including an implant after dental implant surgery, and an arbitrary time around the affected area including the implant input in the post-operative image input step. A diagnostic target image input step for inputting a three-dimensional image of the above, a volume calculation step for calculating a bone volume related to implant implantation in a predetermined space with respect to the implant axis, for a three-dimensional image around the affected area including the implant, Bone resorption amount for calculating the bone resorption amount from the two calculated volumes by causing the volume calculation step to calculate the volume for each of the three-dimensional images input in the postoperative image input step and the diagnosis target image input step. The calculation step is executed by a computer.

  According to the present invention, it is possible to accurately evaluate the three-dimensional bone resorption amount non-invasively and around the entire implant.

The block diagram which shows the hardware constitutions of the personal computer which installed the bone resorption amount measurement program after the dental implant surgery which concerns on one Embodiment of this invention. The flowchart which shows the processing content of the bone resorption amount measuring program which concerns on the embodiment. The figure which illustrates the tomographic image of the periphery containing the implant which concerns on the same embodiment. The figure which illustrates the tomographic image of the periphery containing the implant which concerns on the same embodiment. The figure which illustrates the tomographic image of the periphery containing the implant which concerns on the same embodiment. The figure which illustrates the tomographic image of the periphery containing the implant which concerns on the same embodiment. The figure which illustrates the tomographic image of the periphery containing the implant which concerns on the same embodiment. The figure which illustrates the tomographic image of the periphery containing the implant which concerns on the same embodiment. The figure which illustrates the tomographic image of the periphery containing the implant which concerns on the same embodiment. The figure which illustrates the tomographic image of the periphery containing the implant which concerns on the same embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a hardware configuration of a personal computer (hereinafter “PC”) 10 in which a bone resorption measurement program after dental implant surgery is installed. The north bridge 12 is connected to the CPU 11 that controls various processes and the front side bus FSB.

  The north bridge 12 is further connected to the main memory 13 via the memory bus MB and to the graphic controller 14 and the graphic memory 15 via the graphics interface AGP, and is also connected to the south bridge 16 mainly between them. Execute I / O control.

  The south bridge 16 is connected to a PCI-Express bus 17, a keyboard / mouse 18, a video encoder 19, a hard disk device (HDD) 20, a network interface (I / F) 21, and a multi-disk drive 22. Input / output control with the north bridge 12 is performed.

  It is assumed that in the hard disk device 20, in addition to an OS (operating system), various application programs, various data files, and the like, a bone resorption measuring program after dental implant surgery is installed in advance.

  The video encoder 19 generates and outputs an RGB video signal, which is an analog image signal, from a given digital image signal, and sends it to a display unit (not shown) to display an image. .

  The multi-disc drive 22 can reproduce and record an optical disc medium in accordance with, for example, a CD (Compact Disc) standard and a DVD (Digital Versatile Disc) standard, and includes a helical X-ray CT apparatus, a cone beam type, which will be described later. By reproducing and reading an optical disk medium in which tomographic images and the like acquired by the X-ray CT apparatus are recorded, the tomographic three-dimensional shape data of the patient's palate can be input and recorded in the hard disk device 20.

  It should be noted that the individual elements constituting the PC 10 are very general well-known techniques, and therefore description thereof is omitted.

Next, the operation of the above embodiment will be described.
As a preparation for the execution of this program, an X-ray CT image of an affected area where an implant placement operation has been performed in advance is taken. Imaging is performed with a helical X-ray CT apparatus or a cone beam X-ray CT apparatus.

For example, when the slice interval is 0.125 [mm] and the pixel scale is 0.125 [mm], the error per pixel is 0.001953125 [mm ³ ].

  On the other hand, after a period in which bone resorption occurs, for example, one year, the affected part is imaged again with the helical X-ray CT apparatus or the cone beam X-ray CT apparatus under the same conditions.

  In the PC 10 according to the present embodiment, the post-surgical affected part image and the two-dimensional tomographic image data of the affected part image after the lapse of the period to be diagnosed are stored in the multi-disk drive 22 or the hard disk device 20 in advance. To do.

  When the program according to the present embodiment is executed, first, the image data after the operation and after the elapse of a period to be diagnosed are stored in the multi-disk drive 22 or the hard disk device 20 so that they can be read out at any time (steps S101 and S102).

  Next, an image of the affected area after the operation is first read out (step S103), a three-dimensional image is constructed from these two-dimensional tomographic images, and the axis of the implant in the image is set on each of the sagittal plane and coronal plane.

  3A and 3B illustrate images at that time, and the central axis portion of the implant in the drawing is IA. After setting the axis IA, the subsequent images are changed to those based on the implant axis IA as shown in FIGS. 4A and 4B (step S104).

  Next, a virtual measurement socket that matches the size of the implant is selected, and the image is superimposed and displayed in the image based on the position of the implant (step S105).

  FIG. 5A and FIG. 5B illustrate a state in which the socket SC is selected and displayed. Here, as shown in the drawing, an example is shown in which a cylindrical socket 10.0 having a diameter of 10.0 [mm] and a depth of 14.0 [mm] is used.

Mask data that covers a three-dimensional area corresponding to the luminance value of the bone is created in the selected socket SC (step S106).
FIG. 6 shows the mask data reproduced at this time by hatching. In this state, there is a portion that is not directly related to bone resorption and is not masked because the bone brightness value is low.

  For this reason, in order to reduce measurement errors, the bone is present in the region inside the cylindrical socket SC with respect to a portion not directly related to the bone resorbing portion, that is, a portion below the line CL in FIG. It is assumed that bones are present in all the non-existing areas, and are painted with a mask as shown in FIG.

  Next, with respect to the individual two-dimensional tomographic (slice) images constituting the three-dimensional image, the mask is corrected using the mask drawing tool that the program has in advance (step S108). In other words, a mask is created by the above-described method, but in the case of image data obtained using a cone beam X-ray CT apparatus, there is a fluctuation in luminance, and a portion where the mask is not originally applied to a portion that is a bone is generated. there's a possibility that. Therefore, finally, the user corrects such an incomplete portion by manual operation using the keyboard / mouse 18.

  Although the small portion surrounded by the circle CA in FIG. 9 is originally a bone, it is not recognized as a bone because of low brightness, and is not covered with a mask. Therefore, as shown in FIG. 10, painting is performed using the mask drawing tool of this program. This process is performed on all individual two-dimensional image slices constituting the three-dimensional image (step S109).

  If it is determined in step S109 that the mask processing for all the two-dimensional images has been completed, then the voxel size per pixel is obtained from the pixel scale and slice pitch, and the volume of the mask portion is calculated (step S110).

For example, when the pixel scale is 0.125 [mm] and the slice pitch is 0.125 [mm], the volume of one voxel is
0.125 × 0.125 × 0.125 = 0.001953125 (mm ³ )
It becomes. Using this voxel volume, the mask volume can be calculated by adding the number of pixels in the area painted with the mask in the socket SC by fixing the steps S106 to S109.
The mask part calculated in this way is held for the post-operative implant.

  Next, when it is confirmed that the volume calculation of the mask portion is not for the affected part image after the lapse of the period to be diagnosed (step S111), the affected part image after the lapse of the period to be diagnosed is read again (step S111). S112) Similarly, the processing from step S104 is executed again in order to calculate the mask volume.

  Then, when the mask volume is calculated also from the affected part image after the lapse of the period, it is confirmed in the above step S111, and then the bone resorption amount is calculated from the mask volume calculated after the operation and after the lapse of the period (step S113). ).

  Currently, there is no reference value for the volume of bone resorption, so it is necessary to convert it to the height when measured in two dimensions (step S114). The conversion method is shown below.

For example, when the difference in volume is 2.5 [mm ³ ], the decrease in height due to bone resorption is, for example,
2.5 (mm ³ ) / (5 ² (mm)-2.1 ² (mm)) π = 0.00722 (mm)
(However, 5 (mm): Radius of cylindrical socket,
2.1 (mm): Radius of the implant body. )
It can be calculated by the following calculation.

  According to the above calculation, vertical bone resorption occurred by an average of 0.00722 [mm] in the donut-like alveolar bone of 2.9 [mm] around the implant body.

  In the above example, the obtained vertical bone resorption value is sufficiently small even compared with 0.2 [mm], which is the annual vertical bone resorption that is currently the index. Therefore, the dentist can determine that the implant has been appropriately inserted with reference to the result calculated as described above.

  As described above in detail, according to the present embodiment, since it is based on the image data obtained by the X-ray CT apparatus, it is possible to evaluate the three-dimensional bone resorption amount non-invasively over the entire periphery of the implant. . That is, by utilizing the fact that there is no shape change of the implant body itself embedded in the jaw bone in the image, by measuring the bone volume in a fixed three-dimensional spatial region around the position of the implant, Bone resorption can be calculated very accurately.

  In the above embodiment, the measurement area of the alveolar bone around the implant body can be freely set by arbitrarily changing the setting of the diameter and depth of the measuring socket.

  In that case, by placing an implant symbol (image data pushed on the shape and volume of the implant) provided by each manufacturer of the implant body at the center of the measurement socket, it is overlapped with the socket on this program. Matching can be facilitated.

For reference, the exposure dose (unit: [μSv (microsievert))] in various dental X-ray diagnostic instruments is listed.
X-ray dose exposed to nature in one year: 2400 [μSv]
When taking a jawbone with a medical X-ray CT system: 200 to 500 [μSv]
With CBCT (dental cone beam X-ray CT system)
When shooting in the range of 80 [mm] x 80 [mm]: Less than 100 [μSv]
Chest X-ray: 50 [μSv]
Panoramic X-ray: 40 [μSv]
Dental X-ray photograph: 15 [μSv]
Digital panoramic X-ray: 3-9 [μSv]
Digital dental X-ray photograph: 8 [μSv]
And
With CBCT (dental cone beam X-ray CT system)
When shooting in a range of 40 [mm] × 40 [mm]: 11 [μSv] * 1
: 31-50 [μSv] * 2
(* 1: Provisional guidelines 2009,
* 2: T Okano Dentomaxillofacial Radiology (2009) 38, 79-85)
It becomes.

  Therefore, X-ray exposure in CT imaging in the range of 40 [mm] × 40 [mm] of a three-dimensional dental X-ray CT apparatus (Morita: 3DX MULTI-IMAGE MICRO CT) is the conventional two-dimensional X-ray. Since it is about three times the exposure dose at the time of digital radiography used for fluoroscopic imaging, it is considered that there is no problem in medical ethics when evaluating the amount of information obtained.

  In addition, this invention is not limited to embodiment mentioned above, In the implementation stage, it can change variously in the range which does not deviate from the summary. Further, the functions executed in the above-described embodiments may be combined as appropriate as possible. The above-described embodiment includes various stages, and various inventions can be extracted by an appropriate combination of a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, if the effect is obtained, a configuration from which the constituent requirements are deleted can be extracted as an invention.

  DESCRIPTION OF SYMBOLS 10 ... Personal computer (PC), 11 ... CPU, 12 ... North bridge, 13 ... Main memory, 14 ... Graphic controller, 15 ... Graphic memory, 16 ... South bridge, 17 ... PCI-Express bus, 18 ... Keyboard / mouse, DESCRIPTION OF SYMBOLS 19 ... Video encoder, 20 ... Hard disk drive (HDD), 21 ... Network interface, 22 ... Multi disk drive, AGP ... Graphics interface, FSB ... Front side bus, MB ... Memory bus

Claims (3)

A post-operative image input step of inputting a three-dimensional image around the affected area including the implant after the dental implant operation;
A diagnostic object image input step for inputting a three-dimensional image after an arbitrary time around the affected area including the implant input in the post-operative image input step;
A volume calculation step for calculating a bone volume related to implant implantation in a predetermined space with respect to an implant axis for a three-dimensional image around an affected area including an implant; and
Bone resorption amount for calculating the bone resorption amount from the two calculated volumes by causing the volume calculation step to calculate the volume for each of the three-dimensional images input in the postoperative image input step and the diagnosis target image input step. A program for measuring bone resorption after dental implant surgery, wherein the computer executes the calculation step.   The bone resorption after dental implant surgery according to claim 1, further comprising a height conversion step for converting the bone resorption amount calculated in the bone resorption amount calculation step into a height value measured by a two-dimensional image. Quantity measurement program. The postoperative image input step and the diagnosis target image input step input a three-dimensional image obtained by stacking a plurality of two-dimensional images,
A correction step of correcting a bone volume portion related to implant implantation for each of a plurality of two-dimensional images constituting the three-dimensional image,
The bone resorption measurement program after dental implant surgery according to claim 1, wherein the volume calculation step calculates a bone volume from the three-dimensional image corrected in the correction step.

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