JP3113109B2 - Root canal length measuring instrument - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a root canal length measuring device used for dental diagnosis and treatment.

[0002]

2. Description of the Related Art As a device for electrically detecting the position of an apex and measuring a root canal length, there are a measuring electrode inserted into a root canal and an oral electrode connected to soft tissue in a patient's mouth. A method is known in which a measurement voltage is applied during this period, and the position of the apical portion is calculated from an impedance response value to a root canal impedance obtained between both electrodes.

[0003] This is a simple correspondence system that calculates a tip position of a measurement electrode in accordance with an impedance response value to a resistance value or the like obtained using one type of measurement voltage.
(For example, refer to Japanese Patent Publication No. Sho 62-25381. Hereinafter, this is referred to as Prior Art 1, and a value calculated by such a method is referred to as a simple calculation value.) Alternatively, at least two types of measurement voltages having different frequencies are used. A comparison method of comparing each impedance response value obtained for each measurement voltage and calculating the tip position of the measurement electrode in accordance with the comparison result (for example, Japanese Patent Publication No. 62-2817 and Japanese Patent Application Laid-Open No. 4-64354). See, for example, Japanese Unexamined Patent Application, First Publication No. H11-133125.
And a value calculated by such a method is referred to as a comparative calculated value. ), The prior art 2 calculates a difference between the impedance response values and compares them.
In the prior art 3, a method of obtaining and comparing the ratio of each impedance response value is adopted.

The prior art 1 utilizes the fact that the root canal impedance when the tip of the measurement electrode reaches the apex is approximately 6 kΩ. For example, a measurement voltage having a frequency of 400 Hz is applied between both electrodes. The root canal impedance obtained while inserting the measurement electrode is sequentially measured, and data corresponding to the impedance response value, that is, a simple calculated value is displayed. When a root canal impedance of 6 kΩ is obtained, the tip of the measurement electrode is apical. Is the mainstream, and the process in which the measurement electrode is inserted into the root canal and its tip moves is often shown. However, the root canal impedance value of 6 kΩ is based on the assumption that the inside of the root canal is in a dry state, and if the root canal is bleeding or wet with a chemical solution, the root canal impedance fluctuates. Not suitable for accurate measurement.

Although the root canal impedance is regarded as a combination of a resistance component and a capacitance component, the above-mentioned prior arts 2 and 3 mainly use the characteristic that the capacitance component increases at the apical portion. The data obtained, that is, the comparison calculation value, hardly changes while the tip of the measurement electrode is located at the cervical region, and shows a sharp change as the tip approaches the apex. That is, for example, 400 Hz and 10 k
If the difference or ratio of the impedance response value to the root canal impedance at each measurement voltage of Hz is used as the display value as it is, the display value changes greatly only in the vicinity of the clinically delicate apical part, which is extremely difficult for the operator. It becomes difficult to use and requires careful handling. For this reason, a conversion method of performing a process such as logarithmic conversion or finding a square root of the comparison calculation value to enlarge a minute change and compress and display a sudden change,
A table conversion method or the like that outputs a display value using the comparison calculation value as a pointer has been proposed, but a satisfactory result has not been obtained.

In addition, the prior art 3 can perform accurate measurement in principle in both a wet state and a dry state in a root canal environment, and therefore can be used in a dry root canal like a root canal before filling a root canal. On the other hand, since there is no difference in the measurement results depending on the degree of dryness, it is impossible to confirm whether the inside of the root canal is dry enough to fill the root canal, and the dryness inside the root canal is confirmed by another means It was necessary to do.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of these problems, and an object of the present invention is to provide a root canal length measuring instrument capable of appropriately changing a displayed value, being easy to use, and confirming the degree of dryness. Things.

[0008]

In order to achieve the above object, according to the present invention, a simple calculation method using a simple correspondence method for calculating a tip position of a measurement electrode corresponding to an impedance response value to one type of measurement voltage is provided. And the impedance response values for at least two types of measurement voltages having different frequencies are compared, and a comparison calculation value by a comparison method of calculating the tip position of the measurement electrode corresponding to the comparison result is output to the display unit. The value is calculated.

The data of the simple calculated value and the comparison calculated value are displayed, for example, simultaneously. In addition, it is also possible to output the larger of the two data to the display unit, in which case, in the area to switch between the display of the simple calculation value and the display of the comparison calculation value, using both the simple calculation value and the comparison calculation value, By performing a weighting process on both data and adding them, the data output to the display unit is corrected, and the display can be switched smoothly. Further, a value obtained by performing weighting processing on both data and adding them may be displayed.

[0010]

[Effect] The change in the cervical region is large, a simple calculated value that is effective as the position information of the measurement electrode in the cervical region, and the change near the clinically important apical portion is large, and is not affected by the environment in the root canal. By using together the calculated values that can be accurately measured, it is possible to perform the measurement by utilizing the features of each method. Especially in the cervical region, using the simple calculation value,
In the apical part, the position of the measurement electrode is detected more appropriately by using the comparison calculated value. In the case of the simple correspondence method, when the tip of the measuring electrode is inserted to the apex, if the inside of the root canal is in a dry state, the detected root canal impedance value is about 6 kΩ, while the detected root canal impedance value is about 6 kΩ. Then 5kΩ
Is less than. Therefore, for example, both the simple calculation value and the comparison calculation value are displayed, and the simple calculation value when the tip of the measurement electrode reaches the apex is detected by the comparison calculation value, thereby confirming the simple calculation value in the root canal. It becomes possible to know the degree of drying.

In general, when the tip of the measuring electrode is near the cervical region, the simple calculation value is large, and near the apical portion, the comparison calculation value is large. Therefore, when displaying the larger of both data, the cervical region is mainly used. In the vicinity, a simple calculation value is used, and in the vicinity of the apex, a comparison calculation value is used.
That is, the simple calculated value suitable for detection near the cervical region and the comparative calculated value suitable for detection near the apical region are used properly according to the position of the electrode, and the movement of the electrode during insertion into the cervical region And the movement in the vicinity of the apex are appropriately displayed. Then, by correcting the data of the displayed simple calculation value and the comparison calculation value by the weighting process,
The change of the display value becomes smooth, and the rapid change of the display value is eliminated.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a block diagram of an embodiment, wherein 1 is a tooth, 1a and 1
b indicates the root canal and apex, 2 indicates a measurement electrode, and 3 indicates an oral electrode. In addition, the measuring electrode 2 is not limited to one dedicated to measurement,
For example, a file or the like of an ultrasonic root canal treatment device can be used also as a measurement electrode. 11 an oscillator for outputting a sinusoidal measuring signals of frequency f _1, 12 is the frequency f ₂ higher than f ₁
An oscillator that outputs a sine wave measurement signal of
₁ is a resistor, 14 is a buffer, 15 is a band pass filter of frequency f ₁ , 16 is a band pass filter of frequency f ₂ ,
17 and 18 are AC / DC converters, respectively, and 19 is an A / DC converter.
A D converter, 20 is an arithmetic circuit unit, and 21 is a display. The arithmetic circuit unit 20 has a memory and a comparator function as described below and required arithmetic functions, and the like. As the display 21, an appropriate one such as one using a pointer-type meter or an LED is used. Is done.

FIG. 2 shows an example of a display 21 using LEDs, and reference numeral 21a denotes a display section of the display. 2
Reference numeral 2 denotes a scale, reference numeral 23 denotes a plurality of indicating dots arranged side by side along the scale 2, and reference numeral 24 denotes an apex provided at an end of the scale 22.
An (APEX) mark 25 is a distance mark (unit: mm) provided along the scale 22. 23a is an apical indicating dot used for displaying the apical, indicating an apical dot 2
Among the three, the one at the position of the apical mark 24 is selected. These graduations 22, indicating dots 23, marks 24, 25 and the like are constituted by using multi-color LEDs, but for example, LCDs and color monitors can also be used. In addition, a part of the instruction dot 23 is also used for, for example, an instruction of a working length or an instruction of an auto stop position for stopping or reducing an ultrasonic output at a specific position when an ultrasonic root canal treatment device is used in combination. It is possible to

In this embodiment, for example, a simple calculation value by the simple correspondence method is displayed by blinking the indication dot 23, and a comparison calculation value by the comparison method is displayed by lighting the indication dot 23. When both calculated values are displayed at the same time, the two values can be distinguished from each other by means other than blinking and lighting, for example, by changing the display color.

This embodiment is configured as described above and operates as follows. That is, in FIG.
1 and 12 to operate and apply the measurement voltages of the frequencies f ₁ and f ₂ between the measurement electrode 2 and the oral electrode 3, and the voltage generated in the resistor R ₁ is applied to the buffer 14, each of the filters 15 and 16,
The signal is input to the arithmetic circuit unit 20 via the DC converters 17 and 18 and the A / D converter 19.

The arithmetic circuit section 20 focuses on the low frequency f ₁ and calculates the measurement electrode 2 from the output V _{1 of} the AC / DC converter 17.
Is calculated by a simple correspondence method, and the indication dot 23 corresponding to the tip position of the measuring electrode 2 is sequentially blinked from the upper left based on the result, and the blinking position of the indication dot 23 is moved. The measurement electrode 2
The position of the tip of is displayed. At the same time, the arithmetic circuit unit 20 obtains the ratio of the respective outputs V ₁ and V ₂ of the AC / DC converters 17 and 18 at the respective frequencies f ₁ and f ₂ = V ₂ / V ₁ , and based on the calculation result by this comparison method. All the indication dots 23 from the upper left to the position corresponding to the tip position of the measurement electrode 2 are turned on. If the lighting range includes a blinking portion by the simple correspondence method, the blinking has priority.

In this way, the simple calculation value by the simple correspondence method is displayed at the same time by the blinking of the indication dot 23, and the comparison calculation value by the comparison method is displayed by the lighting of the indication dot 23 at the same time. FIG. 2 illustrates such a display state, in which all the indication dots 23 up to the apical indication dot 23a are lit, and the indication dot 23 'corresponding to the number 1 of the distance mark 25 is blinking. Is indicated by oblique lines.

FIG. 3 exemplifies how the simple calculation value by the simple correspondence method and the comparison calculation value by the comparison method change according to the tip position of the measuring electrode. The horizontal axis is the distance from the apex, and the vertical axis is the display value according to each method.Since the difference in the measurement principle, the simple calculation value changes as shown by the broken line, and the comparison calculation value changes as shown by the solid line. Change. Therefore, if the values calculated by both methods are simultaneously displayed as described above, the blinking portion precedes the cervical portion with a small insertion amount, and the lighting portion overtakes the blinking portion in the middle.

The operator measures the root canal length by inserting the measuring electrode 2 until the apical indicating dot 23a is lit, and stops the insertion at the position where the apical indicating dot 23a is lit. The degree of dryness of the root canal can be known by confirming the blinking points according to the method.
That is, if the inside of the root canal is dry when the tip of the measurement electrode 2 is inserted up to the apex, the detected root canal impedance value is around 6 kΩ, whereas in the wet state it is 5 kΩ.
Ω, and about 4 kΩ if there is bleeding or a drug solution, the position of the distance mark 25 is set in advance so as to correspond to each of these states. If the instruction dot 23 'corresponding to is blinking, it is in a dry state (FIG. 2 shows an example of a display state in such a dry state), and the one between the numbers 1 and 2 is blinking. If it is, the state is wet, and if anything between the numbers 2 and 3 is blinking, it is determined that there is bleeding or that there is a drug solution.

In FIG. 3, since the simple calculated value indicated by the broken line and the comparative calculated value indicated by the solid line intersect substantially at the boundary position between the cervical portion and the apical portion, either of the calculated values is larger. In this case, the movement of the measuring electrode 2 during insertion into the cervical region is appropriately indicated, and the comparison method in which the movement of the measuring electrode 2 at the apical portion is indicated with high sensitivity is displayed. Each feature can be utilized,
The change in the displayed value becomes appropriate and an easy-to-use root canal length measuring instrument can be obtained. It should be noted that simply switching between the display of the simple calculation value and the display of the comparison calculation value results in a sharp change in the display value at the point P where the dashed line and the solid line intersect. Can be switched.

FIG. 4 shows an example in which this processing is performed by weighting, and the vicinity of the point P in FIG. 3 is enlarged. In other words, the area on the horizontal axis is A as shown in the figure according to the distance from the apex.
~ D, the simple calculation value is f ₁ (x), and the comparison calculation value f
₂ (x), in the region A far from the apex, the simple calculated value f ₁ (x) is directly used as the display value, and the region D near the apex is used.
Will use the comparison calculated value f ₂ (x) as it is as the display value. In the regions B and C sandwiching the point P, a correction value obtained by weighting is used in the region B farther from the apex, with emphasis on the simple calculation value, and in the region C near the apex, the comparison calculation value is weighted. f ₃ (x) is used as the display value. This weighting is, for example, the correction value f ₃ (x) = 4 /
5 · f ₁ (x) + 1/5 · f ₂ (x), and in the region C, the correction value f ₃ (x) = 1/5 · f ₁ (x) + 4/5 · f ₂ (x) This is done by:

By such a correction, the display value near the point P changes smoothly as shown by the chain line in FIG.
The discontinuous change of the display value is eliminated. However, if the area is further divided and the weighting coefficient is changed stepwise, the change of the display value can be made smoother. Also, this weighting process is not limited to the vicinity of the point P, but can be performed in a wider range as needed, for example, in the entire region. Since the comparison calculated value mainly changes, the movement of the measurement electrode is clearly displayed, and the change can be made smoother and easier to see by changing the weighting coefficient sequentially according to the site in the root canal. The weighting process as described above is an example of display value correction. In addition, in a region where the simple calculation value and the comparison calculation value are switched, the display value is changed so that both calculation values smoothly switch by drawing an arc of an appropriate diameter. The correction can be performed by an appropriate method, such as a method of correcting the display value or a method of setting a plurality of added values to each calculated value in advance and selecting the most appropriate value according to the case and correcting the display value. It is possible. The process of logarithmic conversion of the comparison calculated value described in the section of the prior art may be performed in the present invention.

[0023]

As is apparent from the above description, the root canal length measuring instrument of the present invention has a simple correspondence system which calculates the tip position of the measuring electrode in accordance with the impedance response value to one type of measuring voltage. The calculated value is compared with each impedance response value for at least two types of measured voltages having different frequencies, and a comparison calculated value by a comparison method of calculating the tip position of the measurement electrode corresponding to the comparison result is displayed on the display unit from both data. The output value is calculated.

Therefore, the simple correspondence method showing the position of the measurement electrode in the cervical region and the position of the measurement electrode in the vicinity of the apex, which is clinically important, are well shown, and are accurate without being influenced by the environment in the root canal. This makes it possible to make use of the features of the comparison method, which can perform various measurements, and to obtain a root canal length measuring instrument that is easy to view and easy to use by performing weighting processing on both data. In particular, by simultaneously outputting both the simple calculated value and the comparison calculated value to the display unit, the root canal length can be accurately measured and the dryness of the root canal can be confirmed, and the larger of the two data is displayed on the display unit. By outputting, it is possible to appropriately display the movement of the measurement electrode.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a diagram showing an example of a display unit in the embodiment.

FIG. 3 is a diagram illustrating a change state of a display value of a simple calculation value and a comparison calculation value.

FIG. 4 is an explanatory diagram of a display value correction method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tooth 1a Root canal 1b Apex 2 Measurement electrode 3 Oral electrode 11,12 Oscillator 20 Arithmetic circuit part 21 Display 21a Display part 23,23 'Indication dot 23a Apical indication dot

Claims (4)

(57) [Claims] A root canal for detecting a position of an apex from an impedance response value obtained by applying a measurement voltage between a measurement electrode inserted into a root canal and an oral electrode arranged in a patient's mouth. A length measuring device, wherein a simple calculation value by a simple correspondence method for calculating a tip position of a measurement electrode corresponding to an impedance response value to one type of measurement voltage, and each impedance response to at least two types of measurement voltages having different frequencies Comparing the values, calculating both the comparison calculated value by the comparison method of calculating the tip position of the measurement electrode corresponding to the comparison result, and simultaneously displaying both the simple calculated value and the comparison calculated value on the display unit. A root canal length measuring device characterized by being configured to output. 2. A root canal for detecting a position of an apex from an impedance response value obtained by applying a measurement voltage between a measurement electrode inserted into the root canal and an oral electrode arranged in the oral cavity of a patient. A length measuring device, wherein a simple calculation value by a simple correspondence method for calculating a tip position of a measurement electrode corresponding to an impedance response value to one type of measurement voltage, and each impedance response to at least two types of measurement voltages having different frequencies Comparing the values and calculating both the comparison calculated value by the comparison method of calculating the tip position of the measurement electrode in accordance with the comparison result, and calculating the larger one of both the simple calculated value and the comparison calculated value A root canal length measuring device configured to output to a display unit. 3. In a region where the display of a simple calculation value and the display of a comparison calculation value are switched, the display unit is operated by performing a weighting process on both data using both the simple calculation value and the comparison calculation value and adding them. 3. The root canal length measuring instrument according to claim 2, wherein the data output to the root canal is corrected to smoothly switch the display. 4. A root canal for detecting a position of an apex from an impedance response value obtained by applying a measurement voltage between a measurement electrode inserted into the root canal and an oral electrode arranged in the oral cavity of a patient. A length measuring device, wherein a simple calculation value by a simple correspondence method for calculating a tip position of a measurement electrode corresponding to an impedance response value to one type of measurement voltage, and each impedance response to at least two types of measurement voltages having different frequencies Comparing the values, calculating both the comparison calculated value by the comparison method of calculating the tip position of the measurement electrode corresponding to the comparison result, and performing the weighting process on both the simple calculated value and the comparison calculated value A root canal length measuring device configured to output a value obtained by adding the values to a display unit.