CN86211111U - Sound-detector for tooth-root length - Google Patents

Abstract

The utility model discloses a sound-detector for tooth-root canal length, which is composed of an oscillator, a constant-current source, an amplifier, a controller, a sound-oscillator and a sound-element. The output terminal of the constant-current source is respectively connected with a standard resistor used for comparison and an exploring electrode through a converting switch. The exploring electrode is inserted into a tooth-root canal. When the resistance measured by the exploring electrode is equal to the standard resistance, the controller is opened, and an audio signal produced by the sound-oscillator causes the sound-element to sound through the controller. The inserted depth of the exploring electrode is the length of the tooth-root canal.

Description

Sound-detector for tooth-root length

The present invention relates to a kind of dental electronic machine, specifically a kind of device of measuring the tooth sono-explorer.

The widely used dentistry sounding of international dentistry circle survey meter is exclusively used in the sono-explorer of measuring tooth, and its theoretical foundation is the biological characteristics theory that proposes of Japanese Jing Shang Noboru (" Japanese tooth section comment " 1972,356:46～53).This theory thinks that gingival sulcus to the impedance (hereinafter to be referred as the gingival sulcus impedance) of oral mucosa equals the impedance (hereinafter to be referred as apical foramen of tooth impedance) of apical foramen of tooth to oral mucosa.The Shang Noboru of Jing is from this theory, a kind of method of measuring root canal length has been proposed, and initial dentistry sounding survey meter and series of products have been designed, as up-to-date sono-explorer(Mark III) in U.S.'s " endodontic's magazine " (JOURNAL OF ENDODONTLCS) 1985 11 10 phases of volume, 421～427 pages of upward exhibitions, its ultimate principle is as shown in Figure 1.This device has the identical electronic circuit of two-way, and each route flapping device and amplifier are formed, and links to each other with speaker by controller.The first via usefulness of making comparisons, the second tunnel does to measure usefulness, and it has two electrodes, and two interelectrode actual measurement impedances are as the FREQUENCY CONTROL impedance of agitator.Behind power connection, the agitator of the first via produces vibration, makes speaker send a sound by amplifier, controller.Reference electrode is hung over patient's bicker mucosa place, exploring electrode inserts suffers from the gingival sulcus (as shown in phantom in FIG.), two interelectrode impedances this moment are gingival sulcus impedances, so the second tunnel agitator produces vibration, equally, make speaker send second sound, this sound is exactly the contrast sound of usefulness of making comparisons.The FREQUENCY CONTROL resistance of regulating the first via makes the tone of first sound and second sound identical, and the resistance of the FREQUENCY CONTROL resistance of the first via equals the gingival sulcus resistance value at this moment.And then exploring electrode inserted gradually suffer from the root canal, two interelectrode impedances are exactly the actual measurement impedance of exploring electrode tip to oral mucosa, in like manner, speaker sends an actual measurement sound, when the tone of actual measurement sound was consistent with the tone of contrast sound, the actual measurement impedance equaled the gingival sulcus impedance, that is equals the apical foramen of tooth impedance, just think that eletrode tip has arrived apical foramen of tooth, the degree of depth that electrode inserts is root canal length.Though this type of dentistry sounding survey meter has demonstrated certain practical value, but still has following problem: (1) inventor's result of study shows that the gingival sulcus impedance is not equal to the apical foramen of tooth impedance, the gingival sulcus impedance alters a great deal under different pathophysiological conditions.As: gingival sulcus impedance meansigma methods and standard deviation.Gingival sulcus for periodontal health is 5.36K Ω ± 1.92, and the marginal gingivitis gingival sulcus is 3.90K Ω ± 1.07, and the periodontitis simplex gingival sulcus is 2.86K Ω ± 0.90.Therefore, the standard of comparison that is used as the apical foramen of tooth impedance with the gingival sulcus impedance is irrational; (2) in detection process, rely on people's ear to judge that the height of two kinds of tones can cause error unavoidably.For above-mentioned reasons, the accuracy rate of this type of dentistry sounding survey meter is lower, and unstable.In addition, when diagnosis, need carry out twice actual measurement, operate loaded down with trivial details.Speaker ceaselessly pipes always and brings fidgety sense also can for patient and doctor in whole diagnosis.

The objective of the invention is to overcome above-mentioned weak point in the prior art and the dentistry sounding sniffer of the measurement root canal length that a kind of electricity characteristic theory with the inventor is provided is foundation.

The electricity characteristic theory that the inventor proposes is thought: when the reference electrode places the oral mucosa place, exploring electrode inserts root canal and when arriving apical foramen of tooth, certainly lead to the rapid variation of an impedance gradient between two electrodes, the rapid change point of this impedance gradient and the biological characteristics of periodontal membrane and oral mucosa are irrelevant, and the apical foramen of tooth volume resistance that size determined of main and apical foramen of tooth is closely related, this impedance mainly is made up of resistance, capacitive reactance only accounts for about 2% and can ignore, thereby the rapid change point of impedance gradient is mainly by the volume resistance decision of apical foramen of tooth.Derive by integration method, the computing formula of apical foramen of tooth volume resistance can be simplified to following formula:

R _T＝ (h)/(Kπr ²)

In the formula: R _T---the apical foramen of tooth volume resistance; Impedance cylindric volume height jumpy takes place in h---apical foramen of tooth position, equals 0.1Cm; The ratio electric conductance of K---cylindric tissue in apical foramen of tooth position or body fluid, ratio electric conductance 0.01475 Ω of available normal saline ^-1Cm ^-1Calculate; The radius of r---apical foramen of tooth.

Task of the present invention is finished by following approach according to above-mentioned electricity characteristic theory, promptly adopts the voltage relative method, with the apical foramen of tooth volume resistance as a comparison benchmark judge whether the exploring electrode that inserts root canal arrives apical foramen of tooth, and its principle as shown in Figure 2.This device has agitator 10, constant-current source 11, rectification amplifier 13, memory amplifier 14, sounding agitator 15, controller 16 and sounding component 17 and exploring electrode 1, a reference electrode 2.With the measuring resistance 18 of usefulness relatively, wherein memory amplifier 14 and sounding agitator 15 connect controller 16 respectively.Outfan at constant-current source 11 is connected to a permutator 12, two contacts of permutator 12 other ends respectively with exploring electrode 1 and relatively the measuring resistance 18 of usefulness join the other end of measuring resistance 18 and reference electrode ground connection.The resistance R of measuring resistance 18 chooses by following formula:

R=0.1/ (0.01475 π r ²)=6.78/ (π r ²) (ohm)

In the formula: π is a pi, r be the apical foramen radius (centimetre).

For Chinese people, the apical foramen mean radius is 0.035～0.044 centimetre, presses following formula and calculates, and the resistance of measuring resistance 18 can be 4.5～7 kilo-ohms.Its optimum is pressed 0.039 centimetre of calculating of total meansigma methods of apical foramen of tooth radius, is 5.6 kilo-ohms.

The work process of this device is such: permutator 12 is connected measuring resistance 18 earlier, agitator 10 produces the consecutive pulses signal, be limited in human body acceptable scope through constant-current source 11 electric currents, and on measuring resistance 18, produce a stable normal voltage signal, this voltage signal is sent into memory amplifier 14 through rectification amplifier 13, adjust memory amplifier 14 till just controller 16 being opened, at this moment, the audio signal from sounding agitator 15 drives the sounding component sounding by controller 16.Permutator 12 is connected exploring electrode 1 more then, and reference electrode 2 is hung over patient's bicker place, and exploring electrode 1 inserts gradually suffers from the root canal, so there is a measured resistance 19 between two electrodes.During beginning, measured resistance 19 overgauge resistance 18, controller 16 can not be opened, and sounding component 17 is sounding not.Controller is opened when measured resistance equals measuring resistance, the sounding component sounding.Just judge that exploring electrode 1 has arrived apical foramen of tooth this moment.

Fig. 1 is the schematic diagram of the dentistry sounding survey meter of Japanese Jing Shang Noboru design.Wherein: 1-exploring electrode, 2-reference electrode, 3, the 5-agitator, 4, the 6-amplifier, 7-FREQUENCY CONTROL resistance, 8-controller, 9-speaker.

Fig. 2 is a schematic diagram of the present invention.

Fig. 3 is the schematic diagram of one embodiment of the invention.

Most preferred embodiment of the present invention is provided by Fig. 3.Agitator is by NAND gate IC ₁, IC ₂, resistance R ₁, R ₂And capacitor C ₁Form, producing frequency is the square-wave pulse signal of 400Hz.Resistance R ₃Play the constant current effect, the sounding agitator comprises two parts, and first is by NAND gate IC ₅, IC ₆, resistance R ₁₂, R ₁₃And capacitor C ₇The agitator of forming, the square-wave pulse signal of generation 2Hz, second portion is by NAND gate IC ₇, IC ₈, resistance R ₁₄, R ₁₅And capacitor C ₈The agitator of forming produces the 800Hz square-wave pulse signal, and the former controls the latter, its objective is to make send gentle in voice.Rectification amplifier is by amplifier IC ₉, resistance R ₈, R ₉, capacitor C ₄, C ₅With diode D ₁, D ₂Form.Memory amplifier is by amplifier IC ₁₀, resistance R ₁₀, R ₁₁, capacitor C ₆W forms with the memory potentiometer.Controller is by not gate IC ₃With NAND gate IC ₄Form.Sounding component adopts piezo-electric ceramic sounding element 20.R ₅Be the measuring resistance of usefulness relatively, its value is 5.6 kilo-ohms.During use, earlier with permutator K and measuring resistance R ₅Connect, agitator produces the pulse signal of 400Hz, through resistance R ₃Generation is less than 10 microamperes stabling current, and at measuring resistance R ₅Voltage signal of last formation amplifies through rectification amplifier, and rectification becomes direct current signal and sends into memory amplifier, regulates memory potentiometer W E point current potential is raise gradually, up to NAND gate IC ₄Till opening.Pass through NAND gate IC from the audio signal of sounding agitator this moment ₄Make sounding component 20 send chimes of doom.And then K switch and exploring electrode 1 connected, exploring electrode 1 is inserted in the root canal, reference electrode 2 hangs over patient's bicker place, during beginning because two interelectrode resistance overgauge resistance R ₅, the E point is in electronegative potential, and NAND gate is not opened, and sounding component 20 is sounding not.When interelectrode resistance equals measuring resistance R ₅The time, the E point is a high potential, NAND gate IC ₄Open, sounding component 20 sends chimes of doom.At this moment, the degree of depth of exploring electrode insertion is root canal length.

Supply voltage in the present embodiment is 9V, IC ₁～IC ₁₀Adopt integrated component, its model can adopt:

IC ₁～IC ₄CD4093B，IC ₅～IC ₈MC14011，

IC ₉～IC ₁₀LM358, R ₃Can select 1M Ω for use.

It is as shown in the table for the model machine of doing by the foregoing description and the result of sono-explorer Mark III type of the prior art clinical trial:

Measuring device	Accuracy rate in the different range of error
							＋1 ～ +0.6 (mm)	＋0.5 ～ +0.1 (mm)	+ ～ -0.5 (mm)	-0.6 ～ -1.0 (mm)	-1.1 ～ -2.0 (mm)	-2.1 ～ -3.0 (mm)
	The present invention	3.8%	8.7%	73.1%	9.6%	3.8%							0.9%
MarkⅢ								0.3%	57.7%	26.8%	15.2%

Annotate: listed accuracy rate is the result who compares with the X skiagram in the table.Last table is carried out statistical analysis can draw following result:

(1) 0～-range of error of 0.5mm in, accuracy rate of the present invention is 73.1%, the Mark III is 57.7%, the former is higher than the latter.Through X 2 test, X ²=5.24, P＜0.05 differs remarkable.

(2) allow measurement error (1～+ 1mm) in the scope, accuracy rate of the present invention is 84.8% for the 95.2%Mark III, the former is higher than the latter.X ²=6.03, P＜0.05 differs remarkable.

Hence one can see that, and measurement accuracy rate of the present invention is greatly improved than prior art.

In addition, the present invention directly measures, and with the having or not as the clinical judgment foundation of sound, thereby easy for operation.

Claims (3)

1, a kind of sounding sniffer of measuring root canal length has electronic circuit and an exploring electrode and a reference electrode of comprising agitator, amplifier, controller and sounding component, it is characterized in that:

A, have a constant-current source 11,

B, have a relatively measuring resistance 18 of usefulness, the resistance R of measuring resistance 18 chooses by following formula:

$\mathrm{R=}\frac{\mathrm{6.78}}{{\mathrm{\pi r}}^2}\mathrm{()}$

In the formula: π is a pi, r be the apical foramen radius (centimetre),

The outfan of c, constant-current source 11 is connected to a permutator 12, and two contacts of permutator 12 other ends join with exploring electrode 1 and measuring resistance 18 respectively, the other end of measuring resistance 18 and reference electrode 2 ground connection,

The said amplifier of d is made up of rectification amplifier 13 and memory amplifier 14.

2, sounding sniffer according to claim 1, the resistance that it is characterized in that measuring resistance 18 is 4.5～7 kilo-ohms.

3, sounding sniffer according to claim 2, the resistance that it is characterized in that measuring resistance 18 is 5.6 kilo-ohms.

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