JPH0370968B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for detecting teeth with caries, that is, cavities.

(Prior Art) Detection and diagnosis of dental caries is the most important and indispensable thing in dental treatment, and diagnosis has conventionally been generally performed using X-ray photographs.

(Problems to be Solved by the Invention) However, there is a risk that X-rays may have various undesirable effects on living tissues, and therefore, the conditions for conducting examinations are becoming stricter from the standpoint of safety. Moreover, it has been difficult to detect early caries even with X-ray examination.

This invention was made in view of the above circumstances, and
By utilizing the difference in the optical properties of carious tooth material and healthy tooth material in response to laser light, cavities can be detected reliably and safely in an extremely short period of time by irradiating the tooth with a weak laser that does not cause tissue damage or pain. The object of the present invention is to provide a caries detection device that applies laser light irradiation that can be used to detect cavities.

(Means for Solving the Problems) In order to achieve the above object, the caries detection device according to the present invention irradiates a tooth with a laser beam from a laser beam irradiation device and detects the reflected light from the irradiation surface. It is characterized by a combination of at least one of a reflected light detector or a surface temperature detector that detects the temperature of the irradiated surface, and a transmitted light detector that detects transmitted light from the tooth surface other than the irradiated part.

(Function) According to the present invention, when the laser beam irradiation device irradiates the occlusal surface of the tooth with a laser beam that has different optical characteristics for carious tooth material and healthy tooth material, the laser beam is reflected on the tooth surface and the laser beam on the tooth material. The absorption and permeation of these substances differ between healthy teeth and carious teeth. for example,
When a carious tooth is selectively irradiated with a laser beam such as a YAG laser or a semiconductor laser that has a high absorption rate and moderate penetration, in terms of reflection on the occlusal surface and transmission from the lateral side of the tooth, healthy teeth are less affected by caries. On the other hand, the temperature of the occlusal surface is much higher than that of healthy teeth. Since penetration into the interior of the tooth is suppressed, the amount of light transmitted to the sides is much smaller than in the case of healthy teeth.

Dental caries can be detected by comparing and examining the differences in optical properties such as reflection, transmission, and surface temperature between healthy teeth and carious teeth when irradiated with laser light using two or more corresponding detectors. is possible.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

First Embodiment (See Fig. 1) This first embodiment is for detecting the surface temperature of the tooth and the transmitted light from the side surface of the tooth. In Fig. 1, 1 is a laser beam irradiation device; Laser light, such as Nd-YAG laser, is used that selectively targets caries, has a high absorption rate, and has moderate penetration into the tooth structure.
Reference numeral 2 denotes a surface temperature detector, which uses a radiation thermometer or an infrared sensor to measure the temperature of the occlusal surface of the tooth D, which is the irradiated area. 3 is a transmitted light detector, which uses a laser light sensor such as a thermocouple element whose surface has been treated to increase the absorption efficiency of the laser light, and is non-contactly mounted on the side of the tooth D. The transmitted light 1b is detected.

Second Embodiment (See Figure 2) This second embodiment is for detecting the occlusal surface reflection of the teeth and the transmitted light from the side surfaces of the teeth. 1 is a laser beam irradiation device, 3 is a transmitted light detector, These are the same as in the first embodiment. 4 is a reflected light detector;
Similar to the transmitted light detector 3 described above, a laser light sensor such as a thermocouple element whose surface has been processed to have a high absorption rate for laser light is used for this, and the reflected light from the occlusal surface is detected. 1c is detected.

Third embodiment (not shown) This third embodiment uses the three types of detectors 2, 3, 4 and the laser beam irradiation device 1 shown in the first and second embodiments to detect the tooth D. This device improves the detection results of occlusal surface temperature, reflected light, and transmitted light to the side. As shown in FIG. 3, an integrating sphere 6 configured to concentrate transmitted laser light and reflected laser light at approximately one point using a hemispherical or partially cut spherical reflector plate 5 is also used. By arranging the transmitted light detector 3 or the reflected light detector 4 at the focal point, it is possible to reduce the loss of sensitive light and perform predetermined detection with extremely high sensitivity.

Further, there is a method of recording the detection results by the transmitted light detector 3 and the reflected light detector 4 on the same time axis on a recorder equipped with a POC mechanism, or using two-dimensional observation using a CCD camera.

(Test Example) Next, a test example conducted by the present inventor will be described in detail.

(1) Test method (1)-1 Method based on the above-mentioned first example As shown in FIG. YAG laser 1 (wavelength
1.06 μm) and measure the temperature (STo) of the occlusal surface of tooth D using a radiation thermometer 2 with an operating wavelength band of 7 to 11 μm. The sensor 3, which uses a 0.5mmφ sheathed thermocouple element whose surface has been processed to have high absorption rate, is placed in a non-contact manner to thermally convert and measure the transmitted laser light (TTs) from the side of the tooth D. .

Note that the irradiation conditions using the YAG laser 1 were set as follows.

Tip output P: 10W, irradiation distance L: 10mm, irradiation diameter D: 2.8mm, power density PD: 162w/ ^cm2 ,
Irradiation time T: 0.2 seconds (1)-2 In method (1)-1 based on the second embodiment, a laser irradiated surface ( The surface above the occlusal surface has been processed to have a high absorption rate for laser light.
A sensor 4 using a 0.5 mmφ sheathed thermocouple is arranged to measure the reflected light from the laser irradiation surface.

The transmitted light detector 3 is the same as in case (1)-1.

(2) Test results (2)-1 Results using method (1)-1 In the case of healthy teeth, as shown in Figure 6A, the temperature at the mating surface (STo) did not rise much and reached the maximum. at 1℃
This is only an increase in the amount of light, and its peak appears one second after the end of laser irradiation. In addition, the transmitted light (TTs) from the side rises rapidly at the same time as the laser irradiation, and falls at the same time as the irradiation ends.

On the other hand, in the case of caries, as shown in Figure 6B, the temperature of the occlusal surface (STo) rises rapidly at the same time as the laser irradiation, reaches its peak after the irradiation, and shows an increase of about 15°C. In addition, although the transmitted light (TTs) from the side rises with laser irradiation, the amount of rise is very small, and the thermocouple reading was about 2/5 of that for healthy teeth.

(2)-2 Results when using method (1)-2 In the case of healthy teeth, as shown in Figure 7A, the reflected light (RTo) from the irradiated surface (occlusal surface) and the transmitted light from the side surface Both lights (TTs) are significantly larger than those in the case of caries (Figure 7B).

(2)-3 Another test example P: 10W, L: 40mm, D: 8mm, PD:
When a radiation thermometer was scanned along the tooth surface under conditions of 20 W/cm ² and T: 5 seconds while continuously irradiating laser light, a temperature distribution curve as shown in FIG. 8 was obtained. As is clear from this, the carious area appears as a high temperature pattern.

(3) Conclusion from the test Since YAG laser light scatters and penetrates within the tooth structure, the surface temperature when the tooth is irradiated with it is:
This shows changes with characteristics different from those in the case of conductive heating. That is, in the case of healthy teeth, the temperature rise on the surface of the irradiated part is small, but there is a considerable amount of light transmitted to the side surfaces.

On the other hand, in the case of a carious tooth, the temperature rise on the surface of the irradiated part due to laser irradiation is much more remarkable than in a healthy tooth, but there is little penetration to the side surfaces.

The reactions described above are extremely sensitive; for example,
In the case of YAG laser light, it was found that it is possible to distinguish between carious teeth and healthy teeth even by using weak laser light irradiation of 162 W/cm ² or less, which does not cause tissue damage or pain.

(Effects of the Invention) As is already clear from the above embodiments and test examples, according to the present invention, healthy teeth and carious teeth have different optical characteristics with respect to laser light, and Taking advantage of the extremely sensitive characteristic response of the human body, we use a weak laser irradiation that does not cause tissue damage, pain, or other undesirable effects on the living body, and can safely and reliably remove tooth decay in an extremely short period of time. can be detected.

In addition, it is possible to detect early caries, which is difficult to detect using conventional X-ray photography, which greatly contributes to the improvement of dental treatment.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of essential parts showing a first embodiment of the present invention, FIG. 2 is a configuration diagram of essential parts showing a second embodiment,
Figure 3 is a structural diagram of the device for improving the measurement sensitivity of this measurement, Figures 4 and 5 are explanatory diagrams of the test procedure, and Figures 6A and B show the test results based on the first example. Graphs 7A and 7B are graphs showing test results based on the second embodiment, and FIG. 8 is a graph showing another test result. Explanation of symbols, 1... Laser light irradiation device (Nd
-YAG laser, semiconductor laser), 2...Surface temperature detector (radiation thermometer), 3...Transmitted light detector (thermocouple sensor), 4...Reflected light detector (thermocouple sensor), 6... Integrating sphere.

Claims (1)

[Scope of Claims] 1. At least one of a reflected light detector that irradiates a tooth with laser light using a laser light irradiation device and detects reflected light from the irradiated surface, or a surface temperature detector that detects the surface temperature of the tooth; A caries detection device that applies laser light irradiation, characterized in that it is combined with a transmitted light detector that detects transmitted light from a tooth surface other than the irradiated part. 2. The laser beam according to claim 1, wherein the laser beam irradiation device is a laser device that irradiates a laser beam that has different absorption characteristics between carious tooth structure and healthy tooth structure and has penetration into the tooth structure. A caries detection device that uses irradiation. 3. The caries detection device applying laser light irradiation according to claim 1, wherein the surface temperature detector is an infrared radiation thermometer or an infrared sensor. 4. A caries detection device applying laser light irradiation according to claim 1, wherein the reflected light detector and/or the transmitted light detector is a laser light sensor such as a thermocouple. 5. A dental caries detection device applying laser light irradiation according to claim 4, wherein an integrating sphere is attached to the laser light sensor.