JPH06277198A - Method for measurement in living body and insert and contrast medium used therefor - Google Patents

Abstract

PURPOSE:To obtain a method for measuring the position of an insert inserted into a living body and the shape of the living body without giving bad influence on the living body. CONSTITUTION:A cutter 11 for removing a dental pulp 10 of a tooth 9 is formed of a ferromagnetic metal. The tooth wherein the cutter 11 is inserted is displayed by means of an MRI imaging apparatus. An operator can confirm the amt. of insertion of the cutter by means of a monitor apparatus and perform removal of the dental pulp 10 in a root canal 3. In addition, a contrast medium using a magnetic substance is filled in the root canal 3 and the contrast medium is displayed by means of the MRI imaging apparatus to measure the shape in the root canal 3 from the shape of the contrast medium. In addition, a filling article is prepd. by using a CAM technology from the shape of the root canal 3 and it is bonded in the root canal 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the inside of a living body by using an MRI image device, and particularly to measuring the position of an inserter inserted inside the living body and teeth and bones exposed in the oral cavity. It is suitable for use in measuring the shape of tissues and the like.

[0002]

2. Description of the Related Art As a technique for measuring the inside of a living body, a CT image device and an MRI image device are known.

[0003]

However, since the CT imager uses X-rays, there is a problem that the patient and the therapist are exposed to X-rays. Further, the MRI imaging device is harmless to the human body, but since it measures the magnetic resonance moment of movable protons (movable hydrogen), it is difficult to see the tooth, bone tissue, and the inserter inserted in the living body. Had. One example thereof will be described using root canal treatment for teeth. If the pulp in the tooth becomes inflamed, remove the pulp with a reamer or file cutter (corresponding to the insert inserted into the living body) and fill the root canal with the pulp removed. Treatment is being given. When removing the pulp in the root canal, it is desirable to completely remove the pulp. Techniques for the therapist to know the distance from the tip of the cutting element to the apex are X-ray photography, electrical measurement technology using an apex meter, and the feel of measuring the insertion amount of the cutting element by the feeling of the cutting element being caught by the therapist. There is a law. However, when using an X-ray photograph, when the patient has the problem of being exposed to X-rays as described above, and the apical opening opens on the side surface of the tooth root,
This opening becomes a shadow of the tooth root depending on the imaging direction, and even if the cutting element projects from the root apex, there is a problem that it can be seen inside the tooth root in an X-ray photograph. In addition, the technique of electrically measuring using an apex meter has a problem that the measurement error greatly increases because the detected value largely changes depending on the measurement environment. Further, in the touch method, roughness may occur in the root canal due to inflammation of dental pulp, and measurement may not be possible even by touch. For this reason, the pulp could not be completely removed, or the cutting element could protrude from the root canal, causing inflammation again after the treatment.

[0004]

It is an object of the present invention to provide an in-vivo measuring method capable of measuring the position of an inserter inserted into a living body and the shape of the living body without adversely affecting the human body, and this measuring method. The provision of an inserter and a contrast medium used in

[0005]

The in-vivo measuring method of the present invention employs a technical means for measuring an object to be measured in a living body by measuring the object to be measured using a magnetic material with an MRI image device. To do. The object to be measured may be an inserter to be inserted into a living body, or a contrast agent having fluidity that covers the object to be measured, such as teeth and bones, which has a low content of mobile hydrogen atoms.

[0006]

The object to be measured is placed in the living body, and the object to be measured in the living body is measured using the MRI image device. Since the inserter is made of a magnetic material, even if the object to be measured is inserted into the bone tissue or the space inside the body or covers the tooth or the bone tissue, the MRI imaging device can be used. The position and shape of the object to be measured can be measured.

[0007]

INDUSTRIAL APPLICABILITY The in-vivo measuring method of the present invention uses a magnetic material for the insert and the contrast agent, so that the position of the insert can be measured with an MRI imager and the shape of the contrast agent can be used to determine the tooth or bone tissue. It is possible to measure the shape of an object to be measured that has a low content of hydrogen atoms. In other words, the position of the inserter and the shape of the measurement target can be measured without adversely affecting the human body.

[0008]

EXAMPLE An example in which the in-vivo measuring method according to the present invention is applied to root canal treatment of a tooth will be described with reference to the drawings. [Structure of Embodiment] FIG. 2 is a schematic block diagram of a restoration creation device for creating a restoration for a root canal. Based on the information on the shape of the root canal 3 (see FIG. 1) measured by the MRI imager 2 and the MRI imager 2, the restoration-creating device 1 stores the restoration 4 (see FIG. 3) for repairing the root canal. Electric circuit 5 for measuring shape
And a root canal restoration filling 4 under the control of this electric circuit 5.
And a three-dimensional cutting machine 6 for forming the.

The MRI image device 2 has a well-known structure.
Magnetic field generating means for generating a magnetic field in the measured portion, magnetic resonance reading means for reading the state of magnetic resonance of the measured portion,
The magnetic resonance reading means comprises a shape measuring means for measuring the magnetic resonance state of the measured portion from the magnetic resonance read by the magnetic resonance reading means, and a monitor device 7 for displaying the measured shape to the user.
It is operated by the user by an external operation device 8 which is common to the electric circuit 5.

First, a healer processes teeth 9 to pulp 10.
Is removed. First, the dental pulp 10 is exposed by cutting the tooth 9. Then, a cutting element 11 such as a reamer or a file is inserted into the dental pulp 10 by a manual operation of a medical practitioner. The cutting element 11 is an insert that is the object to be measured of the present invention, and is made of a flexible magnetic metal (for example, Fe or C).
Metals such as o, Ni, Cu, Cr, Mn, Sr, Sm, and Nd, and oxides, or alloys using these magnetic metals, such as stainless steel, are used. When the cutting element 11 is inserted into the dental pulp 10, the MRI imaging device 2 is operated to three-dimensionally copy the tooth 9 (particularly the root canal 3 portion) to be treated, or the cross-sectional portion of the root canal 3 is taken. Make a copy. The hard part 12 such as dentin or enamel of the tooth 9 is
Although it cannot be measured by the MRI image device 2, the cutting element 11, the pulp 10, the periodontal ligament 15 between the tooth root 13 and the alveolar bone 14, and the gingiva 16 can be measured by the MRI imaging apparatus 2, and the cutting element 11 is displayed on the monitor device 7. The dental pulp 10, the periodontal ligament 15, and the gingiva 16 are relatively clearly imaged. The therapist confirms the insertion amount of the cutting element 11 with the monitor device 7 and allows the end of the cutting element 11 to reach the root apex. Then, a stopper (not shown) provided on the cutting element 11 is operated so that the cutting element 11 does not enter the tooth 9 any more, and then the cutting element 11 is moved.
The pulp 10 is removed by. Thus, the healer
Since it is possible to perform treatment after confirming that the cutting element 11 reaches the root apex and the cutting element 11 does not protrude from the root canal 3, the tooth 9
The pulp 10 can be easily removed without the pulp 10 remaining inside or the cutting element 11 protruding from the root canal 3.

In this embodiment, the insertion amount of the cutting element 11 was first measured, the insertion amount of the cutting element 11 was made appropriate, and then the dental pulp 10 was removed. However, when the dental pulp 10 is removed, the MRI imaging device 2 is operated to copy the tooth 9 to be treated (particularly the root canal 3 portion), and the monitor device 7 confirms the insertion amount of the cutting element 11 while cutting. The dental pulp 10 may be removed up to the end of the root canal 3 by the child 11 (see FIG. 1). Also by this method, the pulp 10 can be easily removed without the pulp 10 remaining in the tooth 9 or the cutting element 11 protruding from the root canal 3. Further, with this method, it is possible to suppress the problem that the cutting element 11 pushes the pulp 10 out of the root canal 3.

Next, the shape of the root canal 3 from which the dental pulp 10 has been removed is measured. The MRI image device 2 includes a root canal 3 to be measured.
In order to read the internal shape, a contrast agent for intraoral measurement of MRI (hereinafter referred to as measurement contrast agent) 17 is filled in the root canal 3 using a filling device such as a syringe or a lenturo (see FIG. 4).
The contrast agent for measurement 17 is also an object to be measured of the present invention using a magnetic substance, and has fluidity when covering at least the surface of the root canal 3 as the object to be measured, and after covering the object to be measured. May be fluid or may solidify. In addition, it is preferably one that can be easily removed after the measurement. An example of the contrast agent for measurement is a mixture of a water-soluble substance such as agar with a magnetic substance, or a gum-like resin with a magnetic substance. Examples of magnetic materials to be mixed are Fe, Co, Ni, C
u, Cr, Mn, Sr, Sm, Nd, etc. and oxides, in the form of fine powder (in the case of fine powder, Samarium cobalt, ferrite, alnico, permalloy, sendust, Fe-Si)
A magnetic alloy such as -B or Nd-Fe-B may be powdered for use) or ionized (or chelated). Then, the tooth 9 from which the dental pulp 10 has been removed is measured by the MRI image device 2.

The electric circuit 5 has a root canal shape reading function 18 for reading the shape of the measuring contrast medium 17 measured by the MRI imager 2, that is, the shape inside the root canal 3. Further, the electric circuit 5 has a root canal shape display function 19 for outputting the read shape of the root canal 3 to the monitor device 7. Then, from the shape of the root canal 3 displayed on the monitor device 7, the user specifies the joint shape of the root canal repairing filler 4 to be joined in the root canal 3 in the electric circuit 5 and also repairs the root canal. The shape of both ends of the restoration filling 4 is simulated to determine the shape of the restoration 4 for root canal restoration (restoration shape determination function 20). Then, the electric circuit 5 uses the three-dimensional cutting machine 6 to create the shape of the restoration material 4 for root canal restoration determined by the restoration shape determining function 20.
The cutting machine controlling function 21 and the three-dimensional cutting machine 6 form the root canal repairing filler 4 from a material such as metal, ceramic, or hard resin. An optical molding machine may be used as a technique for forming the repairing filler 4 with resin. The root canal repairing filler 4 formed by the three-dimensional cutting machine 6 is bonded into the root canal 3 using an adhesive or the like (see FIG. 3).

[Effects of Embodiment] Since the amount of hydrogen atoms held in the root canal 3 from which the hard portion 12 of the tooth 9 and the dental pulp 10 have been removed is small, it is difficult to measure with the MRI imaging apparatus 2. However, by making the cutting element 11 of a ferromagnetic material, the position of the cutting element 11 in the root canal 3 can be measured by the MRI imaging apparatus 2. Thereby, the removal of the dental pulp 10 in the root canal 3 can be performed accurately,
The technique of root canal treatment can be dramatically improved. Also,
In the root canal 3 from which the dental pulp 10 has been removed, instead of the resin that has been conventionally filled, a filler cut from a hard material is joined, so that there is a change in the composition for long-term use, which is a defect of the resin, and internal dead space. It is possible to prevent the occurrence of inflammation of periapical tissues even after long-term use. Further, the shape of the root canal 3 is measured using the contrast agent for measurement 17 and the MRI image device 2, and the shape of the root canal repairing prosthesis 4 is determined from the measured shape of the root canal 3 to determine the CAM. Using root canal restoration filling 4
Thus, the root canal repairing filling material 4 can be created with high accuracy and quickly.

[Modification] In the above embodiment, the root canal treatment for removing the pulp of the tooth is shown as an example, but it is not possible to measure the position of the rotary cutting element for cutting the tooth and use it for the treatment of the tooth. Of course, in addition to teeth, cameras inserted into other living bodies such as bones, stomach, intestines, nasal cavities, blood vessels, removal means for polyps, aspirators, cutters, catheters, probe inserts for probes, etc. It is applicable to all means for measuring the position of. In particular, a space that is not visible or difficult to be imaged by the MRI imaging device, such as the position of the inserter inside the space formed by pumping air, the position of the inserter in the sinus, and the inserter inserted in the bone tissue. It is particularly effective for measuring the position of the insert inside the bone or bone tissue. As an example of using a contrast agent, an example of measuring the shape inside the root canal was shown,
The cutting shape, the outer shape of the tooth, and the jaw position may be measured using a contrast agent and used for the preparation of the crown restoration. The insert may have a magnetic force. Alternatively, a resin containing a magnetic metal may be used. Further, it may be provided on a part of the inserter for position confirmation. It is also possible to impregnate the dental pulp before removal with a contrast agent having a magnetic substance so that the dental pulp can be clearly photographed.
I showed an example of measuring the shape inside the root canal with a contrast agent,
It is possible to measure the shape of the tooth, the jaw bone exposed in the oral cavity, the shape of the measured object having a small number of protons such as the implant structure. In this case, the contrast medium may cover the object to be measured with a large amount of contrast medium, but may be applied thinly by spray coating or a brush.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a tooth for removing pulp.

FIG. 2 is a schematic block diagram of a restoration creation device.

FIG. 3 is a cross-sectional view of a tooth to which a restoration material for root canal repair is joined.

FIG. 4 is a cross-sectional view of a tooth having a root canal filled with a contrast medium for MRI intraoral measurement.

[Explanation of symbols]

 2 MRI imager 11 Cutting element (insertor) 17 Contrast agent for measurement (contrast agent)

[Procedure amendment]

[Submission date] March 5, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

The MRI image device 2 is a magnetic (Ma)
gnetic) · Resonance ·
Abbreviation for Imaging
Usually translated as magnetic resonance imaging. That is, MRI image
The device is a device that applies a magnetic field to the part to be measured by the magnetic field generation means.
And cause magnetic resonance (electron spin) in the measured part,
The state of this magnetic resonance is read by the magnetic resonance reading means and read.
The measured magnetic resonance is processed by a computer and measured
This is a device equipped with a structure for obtaining an image of
And. How to apply the magnetic field of this part to be measured and signal processing
Various methods have been proposed. And measure only the magnetic material
If so, at least MR that can measure electron spin
An I image device may be used. However, in this embodiment, the magnetic
In addition to the sex, the pulp and periodontal ligament can be measured.
An MRI image device capable of measuring a distribution state will be exemplified. Na
The MRI image device 2 of this embodiment is operated by the user by the external operation device 8 which is common to the electric circuit 5.

Claims (3)

[Claims] 1. An in-vivo measuring method for measuring an object to be measured in a living body by measuring the object to be measured using a magnetic material with an MRI image device. 2. An inserter used in an in-vivo measuring method, wherein the object to be measured according to claim 1 is an inserter inserted into a living body. 3. The in-vivo measurement method according to claim 1, wherein the object to be measured is a contrast agent having fluidity that covers an object to be measured, such as teeth and bones, having a low content of hydrogen atoms. Contrast agent used in.