JP3095181B2 - Mechanical property measurement device for temporomandibular joint soft tissue - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the mechanical properties of temporomandibular joint soft tissue used to determine the mechanical properties of temporomandibular joint soft tissue.

[0002]

2. Description of the Related Art When performing prosthetic treatment in the oral cavity from dental caries and missing teeth, not only the restoration of the occlusal contact points of the upper and lower teeth but also the form and material of the prosthesis in consideration of the harmony of the functional occlusal system It is said that a decision should be made. Recently, jaw with noise, pain, movement (open / close movement, lateral movement, forward movement) disorder in the temporomandibular joint due to incongruity of the occlusal contact between the temporomandibular joint and the tooth, which is a component of the functional occlusal system. It is said that arthrosis may be caused.

[0003] Therefore, the mechanism of occlusal contact force transmission to the temporomandibular joint by the finite element method, or the relationship between the contact sliding movement of the teeth and the movement of the mandibular condyle in the temporomandibular joint, disharmony of occlusal contact, X-ray CT and MRI It has been proposed to determine the occlusal contact and occlusal surface morphology of the prosthesis from the relationship with the morphological change of the temporomandibular joint part, but none of them reflects the qualitative information of the temporomandibular joint part.

Further, in daily clinical practice, qualitative information of the temporomandibular joint is only inferred from marginal momentum such as maximum opening, maximum lateral momentum, maximum forward momentum, and maximum rearward momentum. There is no report quantifying the qualitative state of soft tissue, that is, mechanical properties.

[0005]

As described above, although grasping the qualitative state of the temporomandibular joint is an important matter, the present situation relies only on the senses of the surgeon.

Therefore, an object of the present invention is not only to clarify the relationship between the qualitative state of the temporomandibular joint, which plays a part of the functional occlusal system, and the occlusal state of the teeth, but also to provide important information for performing dental treatment. Mechanical property measurement system for temporomandibular joint soft tissue that enables easy and non-invasive quantitative measurement of qualitative information such as the looseness and hardness of a certain temporomandibular joint in a short time in a clinical setting Is to provide.

[0007]

In order to solve the above problems, the present invention provides a random signal generator, a vibrator driven by its output, a vibrator mounted on the tip of the vibrator, and a vibrator mounted on the vibrator. The vibrator vibrates the lower jaw teeth (if there are no healthy teeth in the lower jaw), the periodontal tissue of the lower jaw teeth (there is no healthy tooth in the lower jaw, and if the male part is the excitation point, The two measured systems, the skin tissue of the lower jaw and the soft tissue of the temporomandibular joint, are vibrated by random waves, and the periodontal tissue (or chin) of the lower jaw teeth vibrated by the electric signals proportional to the acceleration of the random waves and the random waves Head) that generates an electric signal proportional to the vibration stress generated in the two measured systems of the skin tissue) and the soft tissue of the temporomandibular joint, proportional to the acceleration of random waves generated from this impedance head Fast Fourier transform (FFT) of the electrical signal proportional to the vibrational stress generated in the two measured systems of the periodontal tissue (or genital skin tissue) of the lower jaw and the soft tissue of the temporomandibular joint excited by random waves )
By processing, the transfer function of the two measured systems is obtained, and this is converted into the mechanical impedance of the two measured systems of the periodontal tissue (or genital skin tissue) of the lower jaw and the soft tissue of the temporomandibular joint. Converted to a certain mechanical mobility, the periodontal tissue of the mandibular tooth (or genital skin tissue) and the soft tissue of the temporomandibular joint from the measured mechanical mobility of the lower jaw tooth
By extracting the mechanical mobility only of the temporomandibular joint soft tissue by subtracting the mechanical mobility of only the temporomandibular joint soft tissue, the data processing unit that calculates the mechanical constant of the temporomandibular joint soft tissue from this mechanical mobility provides a mechanical characteristic measuring device of the temporomandibular joint soft tissue. It was composed.

[0008]

[Action] To obtain mechanical mobility of temporomandibular joint soft tissue only from mechanical mobility including both periodontal tissue and temporomandibular joint soft tissue characteristics of lower jaw obtained from mandibular resting position, integrate upper and lower jaw By doing so, the mechanical mobility of only the periodontal tissue of the lower jaw teeth is measured in a state in which the temporomandibular joint is not excited, and it may be subtracted from the mechanical mobility including both of them.

The temporomandibular joint soft tissue is mechanically viscous,
Considering elasticity and mass, the theoretical curve of mechanical mobility given from this mechanical model is fitted to the actual measured value of mechanical mobility of the soft tissue of the temporomandibular joint only to obtain the viscosity, elasticity and mandibular bone The mass is calculated.

[0010]

1 shows a block diagram of an apparatus for measuring the mechanical properties of temporomandibular joint soft tissue. As shown in the figure, the apparatus for measuring mechanical properties of temporomandibular joint soft tissue includes a random signal generator 1, a low-pass filter 2 having an upper limit frequency of 1 kHz,
Power amplifier 3, vibrator 4, load cell 5, impedance head 6 having vibrator 7, distortion amplifier 8, charge amplifier 9, foot switch 10, analog digital (A /
D) The data processing unit includes a converter 11, a personal computer 12, and a printer (not shown).

The vibrator 4, the load cell 5, and the impedance head 6 are about 9 cm in total length and about 2 cm in weight.
The vibrator 7 which has a unit shape of 00 grams and is mounted on the impedance head 6 can be mounted by appropriately selecting a diameter and a length according to a vibrating part. This is because it is necessary to appropriately select the diameter and length of the vibrator 7 in order to vibrate from the chin portion when there is a difference in the position of the teeth of the lower jaw or when there are no healthy teeth in the lower jaw.

Next, a measuring method will be described. The random signal output from the random signal generator 1 is band-limited to 1 kHz or less by the low-pass filter 2, amplified by the power amplifier 3, drives the vibrator 4, and the vibration is transmitted to the impedance head via the load cell 5. When the mandibular teeth (or genital skin surface) are vibrated by the vibrator 7 attached to the tip of the impedance head 6 in the lower jaw resting position, the periodontal tissue (or genital skin) of the lower jaw teeth Surface) and temporomandibular joint soft tissue are excited. In the mandibular resting position, the balance between the open muscle and the closed muscle is maintained, so there is no effect of fixing the temporomandibular joint by the muscle, and it can be said that the jaw position reflects the characteristics of the temporomandibular joint more.

The impedance head 6 vibrates as an electric signal A proportional to the acceleration of the input random wave and as vibrational stress from the periodontal tissue (or the skin surface of the chin) and the soft tissue of the temporomandibular joint of the mandible. An electric signal F proportional to the force applied to the element 7 is output. These signals A and F are amplified by the charge amplifier 9 and converted into digital data by the A / D converter 11. The output data of the A / D converter 11 is taken into the personal computer 12,
An FFT process is performed, whereby the transfer function of the two measured systems is obtained and converted into mechanical impedance, and further converted into mechanical mobility, which is the reciprocal thereof, and stored.

As shown in FIG. 2, from the mechanical mobility including the characteristics of both the periodontal tissue (or genital skin tissue) and the temporomandibular joint soft tissue of the mandibular tooth obtained from the mandibular resting position, In order to obtain mechanical mobility of soft tissue only, the mechanical mobility, which includes the characteristics of both the periodontal tissue (or genital skin tissue) of the lower jaw and the soft tissue of the temporomandibular joint, is used to determine the periodontal tissue ( Alternatively, it is necessary to exclude the mechanical mobility of the genital skin tissue). Therefore, the bite block made of resin is bitten with moderate occlusal force to the upper and lower jaw molars, and the upper and lower jaws are integrated to eliminate the influence of the mobility of the temporomandibular joint. That is, the mechanical mobility of only the periodontal tissue (or genital skin tissue) of the mandibular teeth is measured and stored in the same procedure as described above in a state where the temporomandibular joint soft tissue is not excited. It has been tested that the bite strength of the resin bite block to eliminate the influence of the mobility of the temporomandibular joint has the smallest variation at moderate bite. Only the periodontal tissue (or genital skin tissue) of the lower jaw from mechanical mobility that includes the characteristics of both the periodontal tissue (or genital skin tissue) of the lower jaw and the soft tissue of the temporomandibular joint acquired earlier The mechanical mobility of the temporomandibular joint soft tissue alone is obtained by subtracting the mechanical mobility in the personal computer using the subtraction program (FIG. 2). The mechanical mobility spectrum of the temporomandibular joint soft tissue is displayed at up to 300 Hz, whose properties are clearly reflected.

Further, a mechanical model of the temporomandibular joint shown in FIG. 3B is devised from the mechanical mobility spectrum of the temporomandibular joint soft tissue shown in FIG. 3A, and the theoretical curve of the mechanical mobility given from this mechanical model is converted to the above-mentioned temporomandibular joint soft tissue. By performing curve fitting to the actual measured value of the mechanical mobility, the viscosity c and the elasticity k of the temporomandibular joint soft tissue and the mass m of the mandible are calculated.

FIG. 4 shows a program flowchart of the personal computer 12 for obtaining mechanical mobility of soft tissue of the temporomandibular joint.

To explain this, as shown in FIG. 4A, first, the impedance head 6 (including the vibrator 7)
Is input as the calibration value of the whole measured value. Next, this mass is measured to determine the transfer function Hm. Further, the complex mass M is obtained by actually measuring the transfer function HM of the periodontal tissue (or genital skin tissue) of the lower jaw and the soft tissue of the temporomandibular joint. Here, m is a complex mass corresponding to Hm. Thereby, the mechanical impedance Z of the periodontal tissue (or genital skin tissue) of the lower jaw and the soft tissue of the temporomandibular joint is calculated (Z 'is the mechanical impedance calculated from M), and the reciprocal thereof, mechanical mobility, is calculated. Convert to λ and save.

Next, as shown in FIG. 4B, at the time of biting the bite block, the mechanical mobility λ 'of only the periodontal tissue of the lower jaw teeth (or the genital skin surface) is calculated and stored by the same procedure as described above. From the mechanical mobility λ of the periodontal tissue (or genital skin tissue) of the lower jaw and the soft tissue of the temporomandibular joint, the mechanical mobility λ of only the periodontal tissue (or genital skin tissue) of the lower jaw was calculated and stored. 'To obtain the mechanical mobility λ _J of the temporomandibular joint soft tissue only. The theoretical curve from the model shown in FIG. 3b can be expressed as 1 / λ _J = (c + jωm−k / jω), and this theoretical curve is curve-fitted to the measured value by the method of least squares so that the temporomandibular joint soft tissue The amount of viscosity c, the amount of elasticity k, and the mass m of the mandible are calculated. j is a complex number and ω is an angular vibration frequency.

The number of data for the FFT processing is 256.
The signal representing the acceleration A and the stress F is multiplied by a Hanning function as a time window. The averaging was performed 16 times, and the sampling time was set to 333 microseconds in order to prevent aliasing in the measurement of the frequency characteristic at the frequency of 1 kHz. As a result, one measurement time is 333 (microseconds) × 256.
Point x 16 times = 1.4 seconds, which is a very short time. In addition, the time for capturing data is about 10 seconds. In the actual measurement, first, the mechanical mobility λ of only the periodontal tissue of the mandibular tooth (or genital skin tissue) and the soft tissue of the temporomandibular joint from the mechanical mobility λ of the mandibular tooth Is subtracted to obtain the mechanical mobility λ _{J of} only the soft tissue of the temporomandibular joint. Therefore, the restraint time of the subject is 1.4 seconds × 2 = 2.8 seconds, and it takes about 30 seconds as the time required to take in the data and perform the subtraction processing. Since the subject was restrained twice in 1.4 seconds each in the measurement, the measurement value was not affected by involuntary movement. Also, no pain is given to the subject.

FIG. 5 shows the mechanical mobility and mechanical properties of the soft tissue of the temporomandibular joint measured by the present apparatus when the excitation point was the lower right central incisor in a 24-year-old woman without any abnormality in jaw function. In order to visually grasp the obtained dynamic parameters, they are displayed on a TMJ mobility triangle (MT diagram) as shown in FIG. The mechanical mobility spectrum of the temporomandibular joint soft tissue has a maximum value at around 70 Hz, and a slope rising to the right until around 70 Hz.
From near Hertz, it shows a downward slope. This mechanical mobility spectrum is curve-fitted to a theoretical curve obtained from the mechanical model of the temporomandibular joint soft tissue described above, whereby the mechanical constants of the temporomandibular joint soft tissue (c,
k, m) are calculated. The mechanical properties of the soft tissue of the temporomandibular joint of the subject were as follows: viscosity c = 137.130 Ns / m, elasticity k = 44706.9 N / m, mass m = 267.686 g.
It can be seen that it is. Further, by comparing the TMJ mobility triangle of the standard value of the mechanical constant of the soft tissue of the temporomandibular joint of a 20-year-old woman with the TMJ mobility triangle of the subject, the looseness of the temporomandibular joint can be visually and intuitively determined.
The hardness can be grasped.

[0021]

According to the present invention, as described above, not only is the relationship between the qualitative state of the temporomandibular joint, which plays a part of the masticatory system, and the occlusal state of the teeth, but also important for dental treatment. Qualitative information such as the looseness and hardness of the temporomandibular joint can be quantitatively measured easily and noninvasively in a short time in a clinical setting.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an apparatus for measuring mechanical properties of temporomandibular joint soft tissue according to the present invention.

FIG. 2 is a schematic view showing a method for calculating a mechanical mobility spectrum of a temporomandibular joint soft tissue by the above device.

FIG. 3 is a contrast diagram of a mechanical model of a temporomandibular joint and a mechanical mobility spectrum.

FIG. 4 is a flowchart of a dynamic characteristic measurement program in a data processing unit.

FIG. 5 is a mechanical mobility spectrum of an experimental example.

FIG. 6 is a diagram showing an example of the above experiment in a mobility triangle.

[Explanation of symbols]

 4 Exciter 5 Load cell 6 Impedance head 7 Vibrator k Elasticity e Viscosity m Mass

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-145649 (JP, A) IEICE Technical Report, The Institute of Electronics, Information and Communication Engineers, June 24, 1987, Vol. 87, No. 86, p. 37-44 Biomechanism 10-Analysis and Integration of Biological Functions-, Biomechanism Society, September 10, 1990, p. 151-161 (58) Field surveyed (Int. Cl. ⁷ , DB name) A61B 5/11 A61C 19/045 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. A vibrator driven by a random signal generator and its output, a vibrator mounted on the tip of the vibrator, and a chin section when the vibrator has no lower jaw teeth or healthy lower jaw teeth When the mandible has no healthy teeth in the periodontal tissue of the mandible or the mandible, and the mandible is used as the excitation point, the two measured systems, the skin tissue of the mandible and the soft tissue of the temporomandibular joint, are excited by random waves. And an electric signal proportional to the acceleration of the random wave and an electric signal proportional to the vibration stress generated in the two measured systems of the periodontal tissue of the lower jaw teeth and the skin tissue of the chin and the soft tissue of the temporomandibular joint excited by the random wave. Impedance head that generates a signal, an electrical signal proportional to the acceleration of the random wave generated from the impedance head, and the periodontal tissue of the lower teeth excited by the random wave. Calculates the transfer function of the two measured systems by performing fast Fourier transform processing on the electrical signal proportional to the vibration stress generated in the two measured systems of the genital skin tissue and the temporomandibular joint soft tissue, and calculates the transfer function of the lower jaw teeth. Tissue or mental skin tissue and temporomandibular joint soft tissue are converted into mechanical impedance of the two measured systems, and then converted into reciprocal mechanical mobility, periodontal tissue of mandibular teeth or chin and soft tissue of temporomandibular joint The mechanical mobility of only the temporomandibular joint soft tissue is extracted by subtracting the mechanical mobility of the periodontal tissue of the lower jaw or the skin tissue of the chin part only from the mechanical mobility of the two measured systems, and the temporomandibular joint soft tissue is extracted from this mechanical mobility. An apparatus for measuring mechanical properties of a temporomandibular joint soft tissue, comprising a data processing unit for calculating a mechanical constant of the joint.