JPH10137268A - Gingiva evaluation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily evaluate the surface layer state of gingivae with high accuracy in a short time by measuring the dielectric constant of the gum, obtaining the moisture density of the gum from the dielectric mitigation of the water of the gum and evaluating the surface layer state of the gingiva based on the obtained moisture density. SOLUTION: For a probe 1 for dielectric mitigation measurement, a single open type electrode 2 is provided inside a cylindrical probe case 3, one end of the electrode 2 of the probe 1 is opened so as to be tightly adhered to a sample S and the other end is connected to an oscillation / reception device 6. An oscillator for generating excitation signals and a receiver for receiving reflected waves from the sample S are incorporated in the oscillation/reception device 6, an oscilloscope for displaying a waveform is connected and a computer 7 for obtaining a complex dielectric constant from an observed waveform and calculating the moisture density is connected. Then, corresponding to the electric length γd of the electrode 2, the average moisture content of the range of approximately an γd from a gingiva surface is measured and the tissue state of the gingiva in the range is evaluated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining the water content of a gum by measuring the dielectric constant of the gum, and for evaluating the surface condition of the gum based on the obtained water content.

[0002]

BACKGROUND OF THE INVENTION Alveolar pyorrhea is the leading cause of tooth loss. In order to prevent this alveolar pyorrhea and maintain the health of the gums, it is important to regularly check the surface condition of the gums and find signs of alveolar pyorrhea.

Conventionally, the following method has been used as a method for evaluating the surface state of the gums. (1) Visually determine gum color, degree of bleeding, and degree of swelling. (2) Measure gum hardness (viscoelasticity). (3) Measure the amount of exudate from the gums. (4) irradiating light having a wavelength corresponding to the absorption wavelength of the blood dye,
The amount of pigment in blood is determined from the scattered light intensity. (5) Irradiate the laser, find the Doppler scattered light intensity accompanying the movement of red blood cells, and evaluate the blood flow condition from the blood flow velocity.

[0004]

However, the conventional methods for evaluating gums (1) to (5) have the following problems.

[0005] The evaluation method (1) requires skill and can be performed only by a specific person.

The evaluation method (2) has low measurement accuracy and lacks reliability of evaluation.

In the evaluation method (3), significant measurement cannot be performed unless the gum health is considerably impaired.

In the evaluation method (4), since the amount of pigment in the blood is measured, it is possible to know the change in the blood flow, but it is not possible to measure the change in the state of the surface tissue of the gum itself.

[0009] The evaluation method (5) measures the momentum of red blood cells. Therefore, this method can also measure the change in blood flow, but cannot measure the change in the state of the surface tissue of the gum itself.

The present invention is intended to solve such problems of the prior art, and to provide a new method capable of easily and highly accurately evaluating the surface state of the gum in a short time. Aim.

[0011]

Means for Solving the Problems The present inventors have found that the moisture concentration in the surface tissue of the gums is a good index for evaluating the surface condition of the gums. The present inventors have found that a method based on measurement of dielectric relaxation of gums is useful because a relatively inexpensive apparatus can measure water concentration quantitatively in a short time, nondestructively, and have completed the present invention.

That is, the present invention measures the dielectric constant of the gum,
Provided is a method for evaluating gums, comprising determining the water content of gums from dielectric relaxation of water in the gums, and evaluating the surface state of the gums based on the obtained water content.

In particular, the dielectric constant of the gum is measured using an open-type electrode having a predetermined electrical length, and a predetermined depth range from the gum surface is determined from the relationship between the measured value of the dielectric constant and the electrical length of the electrode. The present invention provides a method for determining the water concentration at the surface of the gum and evaluating the surface condition of the gum based on the obtained moisture concentration.

Further, the dielectric constant of the gum is measured using a plurality of open electrodes having different electrical lengths, and from the relationship between the obtained measured value of the dielectric constant and the electrical length of the electrode, the moisture in the depth direction of the gum is determined. Provided is a method for determining the concentration distribution and evaluating the surface condition of the gum based on the concentration distribution.

According to the method of the present invention, the dielectric constant of the gums is measured, and the moisture concentration of the gums is determined from the dielectric relaxation of the water present therein. The measurement can be easily performed in a short time of about several minutes.

On the other hand, the present inventors have found that the water concentration in the surface tissue of the gums is an extremely good indicator of the state of the surface tissue of the gums. For example, the normal moisture concentration of the gums increases according to the degree of progression of alveolar pyorrhea. Therefore, it is possible to determine the degree of progression of alveolar pyorrhea based on the moisture concentration of the gums. After brushing, the moisture concentration of the gums becomes higher than before brushing. Therefore, it is possible to determine the degree of the brushing effect based on the moisture concentration of the gums.

Therefore, according to the method of the present invention, it is possible to easily and accurately evaluate the surface condition of the gums, thereby easily detecting signs of alveolar pyorrhea, and improving the brushing effect. Can also be determined.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

In the present invention, the measurement of the moisture concentration of the gums is performed by determining the dielectric relaxation, and the surface condition of the gums is evaluated based on the measurement.

In general, a high-frequency impedance method is used as a method for measuring the water content of the sample surface layer. However, since the high-frequency impedance method does not directly observe the behavior of water on the surface of the sample, there are many factors other than the moisture on the surface of the sample that affect measured values, and there is a problem in reproducibility. In particular, since a large amount of water and electrolytes are present on the surface of the gums, the impedance is low. For this reason, there is a problem that the measurement accuracy is extremely low as compared with the case where the skin or the like in a more dry state is used as a measurement sample.

There is also a problem that information obtained by the high-frequency impedance method is ambiguous at what depth from the sample surface. Furthermore, this method does not provide information on the state of the water, whether it is free water or bound water.

On the other hand, when the water content is measured by measuring the dielectric relaxation, the water content at an intended depth can be quantitatively measured with good reproducibility, and the state of water can be known.

As a method for measuring the dielectric relaxation of the sample surface layer,
Generally, the frequency domain measurement method and the time domain reflection method (hereinafter, T
DR method (abbreviated as Time Domain Reflectometry method)
However, in recent years, research on the latter measurement technique and its application has been actively pursued, and the latter TDR method can be preferably used in the present invention.

In the TDR method, an excitation signal (for example, a step pulse) having a specific waveform is applied to a sample, the reflected wave is observed, and the complex permittivity of the sample is determined from changes in the phase and intensity of each frequency component of the reflected wave. This is a method of measuring the dielectric relaxation in order to determine the physical properties of the sample based on the measured dielectric relaxation.

In the present invention, when measuring the water content of the gums for evaluating the surface condition of the gums, the TDR method itself can be in accordance with a known method described in JP-A-2-110357.

For example, FIG. 1 is a schematic view of a probe and a system for dielectric relaxation measurement used in the known TDR method.
The probe 1 for dielectric relaxation measurement shown in FIG. 1 has a single open electrode 2 provided in a cylindrical probe case 3.
The electrode 2 of the probe 1 is open at one end so that it can be in close contact with the sample S, and the other end is a cable 4 and a connector 5.
Is connected to the oscillation / reception device 6 via the. This oscillation
An oscillator for generating an excitation signal and a sample S
It has a built-in receiver that receives the reflected waves from, and an oscilloscope that displays each waveform is connected. The oscillation / reception device 6 is connected to a computer 7 for obtaining a complex dielectric constant from an observed waveform and calculating a water concentration.

FIG. 2 is a sectional view of the open-type electrode 2 used for the probe 1. As shown in FIG. 1, the electrode 2 includes a core-shaped internal electrode 21 and an external electrode 23 disposed coaxially therearound via an insulator 22.
And the end surface of the external electrode 23 constitute a contact surface with the measurement sample.

FIG. 3 is also a sectional view of a modification 2x of the open-type electrode used in the probe 1. This electrode 2x is also composed of a core-shaped internal electrode 21 and an external electrode 23 disposed coaxially therearound via an insulator 22, similarly to the electrode 2 of FIG. The diameters of the internal electrodes 21 and the external electrodes 23 are reduced while keeping the ratio of the inner diameters constant toward the surface. In this way, the electrical length of the electrode can be shortened by reducing the diameter of the tip surface of the internal electrode 21 that comes into contact with the sample and reducing the area of the tip surface. When the diameter of the tip surface of the internal electrode 21 is reduced, as described above, at an arbitrary position of the electrode,
It is preferable to make the impedance inside the electrodes constant by making the ratio of the inner diameter of the internal electrode 21 to the inner diameter of the external electrode 23 constant. This makes it possible to prevent multiple reflections during dielectric relaxation measurement.

By using the system as shown in FIG. 1, the electric length γd of the electrode 2 used in this system
Accordingly, the average water content in the range of approximately γd from the gum surface can be measured, and thereby the tissue state of the gum in that range can be evaluated.

Here, the electric length γd of the electrode means that an electromagnetic wave V (ω) having an angular frequency ω is provided from one end of a transmission path such as a coaxial cable or the like with a load having a complex dielectric constant ε ^* (ω). Is applied and the reflected wave R (ω)
And the complex dielectric constant ε ^* (ω) of the load, which is included as a parameter γd in the following equation (2).

[0031]

(Equation 2) This electrical length γd can be obtained without covering the side surface of the electrode with an insulator.
The electrode tip can be obtained by immersing the tip of the electrode in a known standard sample having a known complex permittivity ε ^* (ω) of 1 cm or more from the tip surface and measuring the reflected wave.

The electrical length γd is a physical quantity unique to the electrode determined by the shape and size of the electrode, and does not depend on the measuring method. Therefore, the electrical length of the electrode is constant in any of the dielectric relaxation measurement methods such as the frequency domain measurement method and the time domain reflection method (TDR method).

In the present invention, the surface condition of the gums is evaluated not only by the average water content in the range of approximately γd from the gum surface but also in more detailed evaluation. The concentration distribution is obtained as follows, and the surface condition of the gum is evaluated using the obtained water concentration as an index. The method of obtaining the water concentration distribution in the depth direction is a method proposed by the present inventor (Japanese Patent Application No. Hei 7 (1994)).
-150910).

That is, according to the knowledge of the present inventor, when the permittivity is measured using a plurality of open electrodes having different electric lengths for the same portion of the sample, the measured values of the electric length and permittivity of each electrode are obtained. And a certain relational expression holds, and the measured value of the dielectric constant ε
_obs (γd) is represented by the following equation (1).

[0035]

(Equation 3) In the formula, ε _obs (γd) represents a measured value of a dielectric constant measured using an electrode having an electrical length γd.

Ε (z) represents the dielectric constant at a depth z from the surface. This dielectric constant means the sum of the dielectric constant ε _で and the water relaxation strength Δε in a region sufficiently faster than the water relaxation time in the dielectric constant measurement, and the water relaxation strength Δε is the water content of the sample. Is proportional to

Therefore, in obtaining the water concentration distribution in the depth direction in the sample using the above equation (1), first, the dielectric constant of the same portion of the sample is measured using a plurality of electrodes having different electric lengths, Measured value of dielectric constant ε for each electrode with different length γd
Obtain _obs (γd). Then, the dielectric constant ε (x) at the depth x is obtained as the concentration distribution of water in the sample by either the following method a or method b.

Method a: An appropriate function is assumed for the water concentration distribution ε (x), and parameters of the function are appropriately determined (for example, a water concentration gradient, a part where the water concentration is constant). Density, depth, etc.), and changing these parameters, calculate the dielectric constant ε _obs (γd) according to equation (1), and obtain the function and parameter when the calculated value matches the actual measured value.

Method b: The following equation (3) which is an inverse conversion equation of equation (1)

[0040]

(Equation 4) (Where L ^-1 represents the inverse Laplace transform for s = 1 / γd) to determine the water concentration distribution ε (x).

As described above, the dielectric constant of the same portion of the sample is measured using a plurality of electrodes having different electric lengths γd, and the electric length γd is measured.
Obtaining the measured value ε _obs (γ d) of the dielectric constant for each electrode having a different d makes it possible to know the water concentration distribution in the depth direction of the sample.

As a system for measuring the dielectric relaxation when obtaining the water concentration distribution using the equation (1), the known system shown in FIG. 1 can be used. In this case, in order to obtain the measured value ε _obs of the dielectric constant for each electrode having a different electric length γd, the probe 1 is repeatedly replaced with one having a built-in electrode having a different electric length γd. Measure the permittivity with each probe.

Alternatively, as shown in FIG. 4, a multi-probe 1A in which electrodes 2a, 2b, 2c and 2d having different electric lengths are provided in one probe case 3 may be used. The present multi-probe 1A is newly proposed by the present inventor. This eliminates the need to replace the probe every time measurement is performed with electrodes having different electrical lengths, thereby reducing the labor required for the measurement operation. And the total measurement time can be shortened.

In the multi-probe 1A shown in FIG. 4, the basic structure of each of the electrodes 2a, 2b, 2c and 2d is as shown in FIG.
Or, it is the same as the electrode 2 used in the conventional probe 1 shown in FIG. 3, and is an open type comprising an inner electrode 21 having a core wire and an outer electrode 23 coaxially arranged around the inner electrode 21 via an insulator 22. Use electrodes.

The electrode 2 used for the probe 1 shown in FIG. 1 or the electrodes 2a, 2b, 2c and 2d used for the multi-probe 1A shown in FIG.
It is preferable to set within the range of 00 μm, more preferably 10 to 500 μm. If the electrical length is less than 1 μm, the change in the reflected waveform is too small, making accurate measurement difficult. On the other hand, if the electrical length exceeds 1000 μm, the attenuation of the signal in the GHz region increases, and the measurement accuracy decreases.

Each electrode 2, 2a, 2b, 2c, 2d
The electrical length is appropriately selected according to the depth region to be measured within the above-described range, the distance from the surface to the root, the width of a flat part of the gingiva to which the electrodes can adhere, and the like. For example, when evaluating the interdental papilla, the electrical length of the electrode is 10 to 300 μm
In the case where a portion closer to the root of the tooth than the interdental papilla is evaluated, it is preferable that the electric power of the electrode be in the range of 10 to 1000 μm.

Here, each of the electrodes 2, 2a, 2b, 2c, 2
As a method of changing the electrical length of d, for example, the area of the tip surface of the electrode where the internal electrode contacts the sample may be appropriately changed, or the distance between the internal electrode and the external electrode at the tip surface may be appropriately changed. Good. For example, an electrode having an electrical length of 100 μm or less is connected to the electrode at the time of measuring the dielectric constant by setting the tip surface of the internal electrode to a circular shape having a diameter of 10 μm to 270 μm and the interval between the internal electrode and the external electrode to be 10 μm to 310 μm. It is possible to obtain good impedance matching with the different coaxial cable.

In a system for measuring dielectric relaxation using a multi-probe 1A comprising a plurality of electrodes 2a, 2b, 2c and 2d, each electrode is measured in the same manner as in a conventional system for measuring dielectric relaxation using a probe 1. The oscillator and the receiver for dielectric relaxation measurement are connected to the oscilloscope. The oscilloscope may be connected to each electrode or may be connected to a plurality of electrodes. Therefore, as a system configuration in this case, as shown in FIG. 5, for example, an oscillation / reception device 6 having an oscilloscope is connected to each electrode 2a, 2b, 2c, 2d in the multi-probe 1A, and these are connected to a computer. 7, and a two-channel oscillator and receiver corresponding to two electrodes may be connected to one oscilloscope as shown in FIG.

Although the four electrodes 2a, 2b, 2c and 2d are built in the multi-probe 1A shown in FIG. 4, the number of electrodes provided in one multi-probe is not particularly limited. The number of electrodes can be appropriately determined in accordance with a target spatial resolution or the like with respect to a depth region to be measured or a water distribution in a depth direction. In principle, the larger the number of electrodes used, the better the spatial resolution is, which is preferable. However, the width of the flat part of the gingiva where the multi-probe tip can be in close contact, the manufacturing cost of the device, the time required for calculation, It is preferable to use 2 to 10 probes in terms of the thickness of the probe.

In both the probe 1 shown in FIG. 1 and the multi-probe 1A shown in FIG. 4, a guide for bringing the electrodes 2, 2a, 2b, 2c, 2d into close contact with the gum surface as necessary. Each electrode 2, 2a, 2b, 2c,
Pressing means such as a spring that presses 2d against the gum surface with a predetermined pressure, sensors for simultaneously acquiring information other than moisture, such as a temperature sensor, a pH sensor, a Doppler blood flow meter, a color tone meter, and a vibration for measuring viscoelasticity Probe, ultrasonic probe for tomography, microphone, optical fiber, 1
A receiving device for electromagnetic waves of KHz to 100 MHz can be provided.

[0051]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments.

Example 1 The relationship between the water content of the gums and the degree of alveolar purulence was determined as follows.

(1) Calculation of gum moisture concentration (1-1) Preparation of electrode The electrode has the shape shown in FIG.
5, 170, and 270 μm electrodes and electrodes having the shape shown in FIG. 3 and an electrical length of 20 μm were produced.

In this case, the internal electrode 2 is used as the electrode material.
1 and the external electrode 23 were both made of copper, and their surfaces were plated with gold to prevent corrosion. Insulator 2 between these electrodes
2 was Teflon.

The electrical length of the formed electrode was determined as follows. That is, acetone whose dielectric spectrum is already known is used as a standard sample, and the tip of the electrode is placed in acetone for 1c.
m or more, and using a step pulse as an excitation signal, T
The reflected wave was measured by the DR method. Then, using the excitation signal and the measured reflected wave, using the electrical length γd as a parameter,
The dielectric spectrum was calculated from equation (2). In this case, the dielectric spectrum was calculated while changing the value of the electrical length γd, and the electrical length γd when the calculated value of the dielectric spectrum most coincided with the known dielectric spectrum of acetone was defined as the electrical length γd of the electrode.

(1-2) Preparation of Dielectric Relaxation Measurement System The above electrodes were mounted in a cylindrical probe case to prepare a dielectric relaxation measurement probe.

A coaxial cable was connected to the electrode, and an SMA connector terminal was provided at the end. On the other hand, 20G
Hz digital oscilloscope with built-in TDR measurement channel (HP547, manufactured by Hewlett-Packard Company)
50A) was prepared, and the connector terminal was connected to the channel of this digital oscilloscope. The oscilloscope was connected to a personal computer and controlled.

(1-3) Measurement of dielectric constant and calculation of moisture concentration in the gums The gums are a kind of mucous membrane and do not have a stratum corneum like ordinary skin. Therefore, it is considered that the gums have a substantially uniform water distribution in the depth direction. However, the most surface part is always in contact with saliva, and is considered to have a different moisture concentration from the deep part. If the mouth is kept open for a certain period of time, the water on the mucosal surface layer decreases due to evaporation of the water. Therefore, the surface layer of the gum is different from the deep part, and it is considered that the moisture concentration easily fluctuates due to a change in environment.

It is not clear how deep such an area that is susceptible to the external environment is, or what the water distribution pattern is in this area. However, approximately, it is considered that a linear gradient of the water concentration is generated from the deep part toward the surface part.

Here, a is the moisture concentration at the outermost surface, and b is the depth at which the concentration gradient ends and the water content reaches a certain moisture concentration region.
Assuming that the moisture concentration in the region where the moisture concentration is constant is c, the moisture concentration deep from the skin surface layer can be expressed as shown in FIG.

On the other hand, it can be approximated that the skin is composed of water and protein. The relaxation strength of pure water is 73, and the dielectric constant of water in a frequency region sufficiently faster than the relaxation of water is 5.3. In addition, since proteins are much larger molecules than water, they do not relax in the frequency range where dielectric relaxation of water occurs. The dielectric constant in a frequency region sufficiently faster than the relaxation of water slightly differs depending on the type of protein, but can be approximated by the dielectric constant 3.3 of nylon, which is a typical polyamide. Therefore, the dielectric constant (ε) in the frequency domain where the water relaxation process ends can be expressed as the following equation (4) as a function of the water concentration (Cw).

[0062]

Ε = 73 · Cw + (5.3-3.3) · Cw + 3.3 (4) This equation (4) is used to calculate the water concentration distribution (depth x from surface layer x) in FIG.
vs. moisture concentration), it is possible to obtain the depth distribution of the dielectric constant on the skin surface. That is, FIG.
From

[0063]

(Equation 6) Therefore, equation (4) can be expressed as the following equation (4 ′).

[0064]

７ = 73 · [(ca) · x / b + a] + (5.3−3.3) · [(ca) · x / b + a] +3.3 (4 ′) When this dielectric constant distribution is applied to the above equation (1), the following equation (5) is obtained.

[0065]

(Equation 8)

Then, a male having healthy gums was used as a test subject, and the dielectric constant of the gums (interdental papilla of the upper incisor) was measured using six electrodes having different electrical lengths as follows. . That is, after the mouth was washed with tap water, the measurement site was lightly wiped with a nonwoven fabric, and the first measurement was performed. After 5 minutes, the measurement was performed again.

In this case, the subject kept his mouth open between the first measurement and the second measurement. In addition, an auxiliary device was inserted into the oral cavity so that the upper lip did not touch the measurement site.

Using the electrical length γd and the observed value of the dielectric constant at the electrical length γd, the combination of the values of a, b, and c in the equation (5) is determined by the simplex method so that the least square error is minimized. It was determined and the water concentration distribution was determined.
The observed value was applied to the obtained water concentration distribution, and the water concentration corresponding to the dielectric constant observed at each electrical length γd was obtained. Table 1 shows the results. FIG. 8 shows the relationship between the depth from the gum surface and the water concentration.

[0069]

[Table 1] Moisture concentration change rate immediately after mouthwash 5 minutes after mouthwash Electrical length Water concentration Moisture concentration 5 minutes after mouthwash / immediately after mouthwash [μm] [g / cm ³ ] [g / cm ³ ] 20 0.531 0. 468 0.881 60 0.514 0.482 0.938 80 0.508 0.487 0.959 115 0.505 0.491 0.972 170 0.500 0.494 0.988 270 0.498 495 0.994

FIG. 8 shows that 5 minutes after the mouth washing, 15 minutes from the surface.
The water concentration is reduced in the area of about μm,
It can be seen that the water concentration in the deep part has hardly changed.

Table 1 shows, for each electrode of each electrical length, the ratio of the water concentration 5 minutes after the mouth washing to the water concentration immediately after the mouth washing as a water concentration change rate. As a result, the electrical length is 2
In the case of the 0 μm electrode, the measured value greatly fluctuates in accordance with the change in the water content of the surface layer. Also, approximately
It can be seen that if the electrode has an electrical length of 115 μm or more, the moisture concentration in the deep part can be measured almost without being affected by the surface layer.

Then, using an electrode having an electrical length of 170 μm, water was measured in the interdental papilla of the maxillary incisor using 10 male subjects aged 25 years or older as subjects.

(2) Relationship between the evaluation of the alveolar pyorrhea by a dental hygienist and the water content of the gums On the other hand, the subject 1 who measured the water content of the gums in the above (1-3)
One dental hygienist evaluated the progression of alveolar pyorrhea on the gums on a 4-grade scale with a gingivitis index of 0 to 0. Here, the gingivitis index 0 indicates a healthy state, and the gingivitis index 3
Indicates that the gingiva is swollen and bleeds easily. The gingivitis indices 1 and 2 represent an intermediate state between them.

FIG. 9 shows the relationship between the gingivitis index evaluated by a dental hygienist and the water concentration obtained in the above (1-3) using an electrode having an electric length of 170 μm.

FIG. 9 shows that the moisture concentration of the gums is used as an index.
It can be seen that the alveolar pyorrhea can be evaluated.

Example 2 The relationship between the water content of the gums and the brushing effect was determined as follows.

Three male subjects with healthy gums and ages 31 to 36 were used as subjects. After each subject had daily brushing around 7 am, the gum moisture was measured between 11:00 and 12:00. Thereafter, brushing was performed using a commercially available toothpaste and a toothbrush, the mouth was washed with tap water, and 10 minutes after the mouth was washed, the moisture in the gums was measured again. The measurement was repeated for 3 days in the same manner. However,
On the first measurement day, the whole oral cavity was brushed for 1 minute, and on the second day, the whole oral cavity was brushed for 2 minutes, and on the third day, for 3 minutes. FIG. 10 shows the relationship between the brushing time and the amount of change in the moisture concentration of the gums before and after brushing (ie, the value obtained by subtracting the moisture concentration before brushing from the moisture concentration after brushing).

FIG. 10 shows that the longer the brushing time, the higher the moisture concentration in the gums. this is,
This is because the stimulation by brushing increased the blood flow of the gums and temporarily made the blood vessels thicker. Therefore, it can be seen that the brushing effect can be determined using the moisture concentration of the gum as an index.

[0079]

According to the method of the present invention, the moisture concentration of the gums is measured nondestructively according to the dielectric relaxation measurement such as the time domain reflection method (TDR method), and the obtained gum concentration is used as an index. Since the surface state of the gum is evaluated, the surface state of the gum can be accurately evaluated in a short time.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a probe and a system for measuring a moisture concentration by dielectric relaxation measurement using the probe.

FIG. 2 is a sectional view of an electrode for dielectric relaxation measurement.

FIG. 3 is a sectional view of an electrode for dielectric relaxation measurement.

FIG. 4 is a schematic diagram of a multi-probe.

FIG. 5 is a schematic diagram of a system for measuring a water concentration by dielectric relaxation measurement using a multi-probe.

FIG. 6 is a schematic diagram of a system for measuring a water concentration by dielectric relaxation measurement using a multi-probe.

FIG. 7 is a diagram illustrating a relationship expected between the depth from the gum surface and the water concentration.

FIG. 8 is a diagram showing the relationship between the depth from the gum surface and the measured value of the water concentration.

FIG. 9 is a graph showing the relationship between the gingivitis index and the water content of the gums.

FIG. 10 is a diagram showing a relationship between brushing time and a change in water concentration before and after brushing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Probe 1A Multi probe 2, 2a, 2b, 2c, 2d Electrode for dielectric relaxation measurement 3 Probe case 4 Coaxial cable 5 Connector 6 Oscillator / receiver 7 Computer 21 Internal electrode 22 Insulator 23 External electrode

Claims (6)

[Claims] 1. A gum evaluation comprising measuring a dielectric constant of a gum, obtaining a moisture concentration of the gum from dielectric relaxation of water in the gum, and evaluating a surface state of the gum based on the obtained moisture concentration. Method. 2. A method for measuring the dielectric constant of a gum using an open-type electrode having a predetermined electrical length, and obtaining a predetermined depth range from the gum surface based on the relationship between the measured value of the dielectric constant and the electrical length of the electrode. The method for evaluating gums according to claim 1, wherein the moisture concentration is determined by the following method. 3. A method of measuring the dielectric constant of a gum using a plurality of open-type electrodes having different electrical lengths, and determining the moisture in the depth direction of the gum from the relationship between the obtained measured value of the dielectric constant and the electrical length of the electrode. The method for evaluating gums according to claim 1, wherein a concentration distribution is obtained. 4. The measured value of the dielectric constant and the electrical length of the electrode are given by the following equation (1). (Where ε _obs (γd) represents a measured value of the dielectric constant measured using an electrode having an electrical length of γd, and ε (z) represents z from the surface.
Represents the dielectric constant at a depth of. 4. The gum evaluation method according to claim 3, wherein the relationship between the depth z and the dielectric constant ε (z) is determined so as to satisfy the condition (3), and the water concentration distribution in the depth direction is determined. 5. The gum evaluation method according to claim 3, wherein the water concentration distribution in the depth direction is obtained by the inverse conversion equation of the equation (1). 6. The gum evaluation method according to claim 1, wherein an open electrode having an electric length of 1 to 1000 μm is used, and a moisture concentration in a range of 1 to 2000 μm in depth from the gum surface is determined.