JP2011055982A - Dental instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means and an instrument to reinforce a tooth from which the pulp is removed more safely and effectively than heat treatment of the dentin. <P>SOLUTION: The dental instrument comprises a handpiece portion and a control device. The handpiece portion comprises a pulp cavity insertion plug to irradiate the dentin of the tooth with ultraviolet rays and a source of ultraviolet rays, and the pulp cavity insertion plug has an ultraviolet ray irradiation section. The dental instrument can mechanically strengthen the tooth by irradiating the dentin with ultraviolet rays in the pulp cavity of the tooth form which the pulp is removed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a dental device for mechanically strengthening a tooth from which pulp has been removed. More specifically, the present invention relates to a dental apparatus for mechanically (or mechanically) strengthening a tooth by irradiating ultraviolet rays onto the dentin of the tooth in the dental pulp cavity.

  In dental treatment, a treatment for removing the dental pulp (treatment for removing the dental nerve) due to advanced caries is routinely performed. However, since a cavity is formed in the central part of the tooth from which the pulp has been removed, it is known that the mechanical strength of the tooth is significantly reduced due to the structure (Non-Patent Document 1). In order to reinforce such a tooth, the treatment which builds the support | pillar which consists of a metal, resin, etc. in the center part of the tooth | gear in which the dental pulp existed is generally performed (nonpatent literature 2).

  The treatment to reinforce the tooth from which the pulp has been removed with an artificial material, when the mechanical properties of the tooth and the reinforcing material are different, may cause excessive stress concentration inside the tooth, and the tooth may break. Therefore, it can also be an inducement of tooth extraction (Non-patent Document 3). Actually, plaque control can prevent bacterial infections such as dental caries and periodontal disease, but it is difficult to prevent dental fracture caused by excessive force (Non-patent Document 4). A method for safely and effectively reinforcing a tooth from which the pulp has been removed has not yet been established, and strengthening a tooth with such reduced strength has become an urgent issue to be solved.

  Conventionally, various studies have been made on the mechanical properties of teeth in different environments such as aging or drying and wetting (Non-Patent Documents 5 to 7). However, there has been almost no effort to strengthen the tooth itself by physical stimulation. Only by heating the dentin exposed to the pulp cavity to a surface temperature of 70 ° C. to 140 ° C., the collagen network structure becomes dense, and the mechanical strength of the teeth is increased. It has been found to improve (Patent Document 1 and Non-Patent Document 8).

  By the way, in the dental field, ultraviolet rays are not used on a daily basis. In the past, ultraviolet rays were sometimes irradiated to solidify the filling (for example, photopolymerization resin) into the dental pulp cavity. However, since currently used photopolymerization resin is cured by visible light, only a light irradiator that irradiates visible light from which an ultraviolet region or a near infrared region is removed by a filter is used. Alternatively, for the purpose of sterilization, a device for irradiating a sterilization light (for example, ultraviolet light) on a dental treatment handpiece and irradiating the sterilization light from a blade (dental treatment tool) has been devised (patent) Reference 2).

International Publication No. 2008/47490 JP 2005-73829 A

E. Reeh et al., J. Endodonics, 15, pp. 512-516, 1989 Yuji Tsubota, Japanese Dental Review, Vol. 65, No. 10 (No. 756), 53-64, 2005 M. Hayashi et al., Dental Materials, 22, 477-485, 2006 P. Axelsson et al., J. Clinical Periodontology, 31, 749-757, 2004 M. Jameson et al., J. Biomechanics, 26, 1055-1065, 1993 B. Kahler et al., J. Biomechanics, 36, 229-237, 2003 D. Bajaj et al., Biomaterials, 27, 2507-2517, 2006 M. Hayashi et al., J. Dental Research, 87, 762-766, 2008

  An object of the present invention is to provide means for reinforcing a tooth from which pulp has been removed more safely and effectively than the above-described treatment by heating dentin, and an apparatus therefor.

  The present inventors have found that by irradiating dental dentin with ultraviolet rays on the long wavelength side for 5 to 15 minutes, the bending strength of the dentin is increased approximately twice with direction specificity. The present invention has been completed based on the above.

  The present invention provides a dental apparatus for mechanically strengthening a tooth from which the pulp has been removed, the dental apparatus comprising a handpiece part and a control device, the handpiece part being in the dentin of the tooth A pulp cavity plug for irradiating ultraviolet light and an ultraviolet light source are provided, and the pulp cavity plug has an ultraviolet irradiation section.

  In one embodiment, the ultraviolet irradiation section has a length substantially equal to the depth of the dental pulp cavity.

  In one embodiment, in the said ultraviolet irradiation part, an ultraviolet-ray is irradiated from the front-end | tip part and a side part.

  In one embodiment, the ultraviolet irradiation section has a conical shape having a plurality of steps.

  In one embodiment, the ultraviolet irradiation section includes a chip that covers the ultraviolet irradiation section and is detachable.

  In one embodiment, the chip can irradiate by scattering ultraviolet light.

  In one embodiment, the ultraviolet light has a wavelength of 320 nm to 400 nm.

  In one embodiment, the ultraviolet light source is an ultraviolet light emitting diode.

  In one embodiment, the dental apparatus includes output control means for the ultraviolet light source.

  ADVANTAGE OF THE INVENTION According to this invention, the dental apparatus which can reinforce the tooth | gear from which the pulp was removed safely and effectively is provided. By using the apparatus of the present invention, it is possible to easily reinforce a tooth that has become brittle by removing the pulp by treatment such as caries, and the health of the tooth that has lost the pulp over a longer period of time can be maintained. Therefore, it leads to the improvement of quality of life (QOL).

It is a schematic diagram for demonstrating an example of the dental apparatus of this invention. It is a graph which shows the result of the cantilever bending test about the human dentin rod-shaped sample irradiated with ultraviolet-ray on various conditions. It is a graph which shows the result of a cantilever bending test about the human dentin rod-shaped sample immersed in Hanks balanced salt solution (HBSS) after ultraviolet irradiation on various conditions, and a line contraction rate. It is a graph which shows the quantity of various collagen intermolecular bridge | crosslinking before and behind ultraviolet irradiation. The figure which shows the reference | standard vibration of the amide which prescribes | regulates the planar structure of collagen, and the infrared absorption spectrum obtained by the micro-infrared spectroscopy analysis about the human dentin sample irradiated with ultraviolet-ray on various conditions. It is a Raman spectrum obtained by the microscopic laser Raman spectroscopic analysis about the human dentin sample irradiated with ultraviolet-ray on various conditions.

  A tooth is a surface layer structure made of enamel, dentin, and cementum. Anatomically, it consists of a dentine and a crown made of enamel covering it, and a dentine and a cementum covering it. Divided into tooth roots. There is a pulp cavity in the center, which is filled with pulp, which is the nerve of the tooth. When the dental pulp, which is a nerve of the tooth, is removed due to caries or the like, the pulp cavity is exposed as a cylindrical cavity. The exposed part of the pulp cavity is dentin.

  Dentin is about 25% by volume collagen fiber and about 50% by volume hydroxyapatite. In the dentin, a large number of dentinal tubules having a direction from the pulp cavity outward are running.

  By irradiating the dentin with ultraviolet rays, the cross-linked structure inside the collagen increases, and the distance between the centers of the triple helix of the collagen fibers is reduced. This phenomenon is also observed when dentin is heated (Patent Document 1 and Non-Patent Document 8). The denaturation temperature of protein is about 55 ° C to 60 ° C, and the denaturation point of collagen is about 105 ° C to 110 ° C. Therefore, the network structure of collagen containing hydroxyapatite crystals becomes dense by heating, and the mechanical strength of the teeth is improved. In particular, when the dentin in the dental pulp cavity is heated to 70 ° C. to 140 ° C., the bending strength, the tensile strength, and the fracture toughness value are remarkably improved specifically in the running direction of the dentinal tubule. However, when immersed in Hank's Balanced Salt Solution (HBSS) after heating, the bending strength of the dentine returns almost the same as before heating. On the other hand, when the dentin is irradiated with ultraviolet rays, the bending strength obtained by the ultraviolet irradiation is maintained even after being immersed in HBSS. Therefore, the teeth can be mechanically strengthened more effectively by irradiating with ultraviolet rays than by heating the dentin in the oral cavity.

  Hereinafter, the dental apparatus of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view for explaining an example of a dental apparatus of the present invention. The dental apparatus 1 of the present invention includes a handpiece unit 10 and a control device 20. In FIG. 1, the control device 20 is a housing, and the handpiece unit 10 is provided from the housing via a flexible connection unit 30. The dental apparatus of the present invention may be a cordless type in which a control device and a handpiece unit are integrated. The handpiece part 10 of the dental apparatus 1 illustrated here may be a shape suitable for irradiating ultraviolet rays in the oral cavity, and is not limited to the handpiece, and may be a mouthpiece or the like. In this specification, the case of the shape of a handpiece will be described as an example.

  As shown in FIG. 1, the handpiece unit 10 includes a handle unit 11, a protective tube 12, a pulp cavity insertion plug 13 (including an ultraviolet irradiation unit 14), an ultraviolet light source 15, and an irradiation switch 16.

  The handle part 11 is a part held by a user (for example, a dentist). The handle portion 11 can be designed in a size and shape that can be gripped by the user and is easy to operate. For example, the handle portion 11 is formed of plastic or the like. The handle portion 11 is preferably a cylindrical shape having a diameter of about 3 cm from the viewpoint of ease of gripping.

  The protective tube 12 is a part that prevents the below-described pulp cavity plug 13 from directly touching the patient's mouth, particularly the patient's lips and tongue. For example, since the protective tube 12 is provided, it is not necessary to keep the mouth open over the time when the teeth are irradiated with ultraviolet rays, and the mouth can be closed by biting the protective tube 12. The material of the protective tube 12 is not particularly limited. Moreover, it has a size and a shape that are convenient for insertion into the mouth and that do not feel uncomfortable.

  The pulp cavity insertion plug 13 is a means for inserting the pulp cavity into the pulp cavity and irradiating the teeth (particularly dentin) with ultraviolet rays, and is provided with an ultraviolet irradiation unit 14 at the tip thereof. In the pulp cavity plug 13, for example, the ultraviolet light generated from the ultraviolet light source 15 is transmitted to the ultraviolet irradiation unit 14 through the ultraviolet spectroscopic lens as necessary, and the ultraviolet irradiation is irradiated from the ultraviolet irradiation unit 14 toward the dentin. Is done. Therefore, a light guide such as an optical fiber may be provided in the dental pulp cavity plug 13. The pulp cavity insertion plug 13 has an outer diameter smaller than the diameter of the pulp cavity (usually 3 mm or less), and the outer diameter is preferably 1 mm to 2 mm.

  The ultraviolet irradiation unit 14 is made of a material (for example, resin or glass) that transmits ultraviolet rays. Moreover, you may mount | wear with the chip | tip which covers the ultraviolet irradiation part 14 and can be attached or detached to the ultraviolet irradiation part 14 (not shown). Such a chip is usually made of resin, and is preferably disposable.

  The ultraviolet irradiation unit 14 is preferably configured to uniformly irradiate the entire dentin exposed to the pulp cavity. For example, it is preferable to have a length substantially equal to the depth of the dental pulp cavity so that ultraviolet rays are irradiated from the tip and side portions. In this case, only the ultraviolet irradiation part 14 of the dental pulp cavity plug 13 is inserted into the dental pulp cavity.

  As a shape which irradiates an ultraviolet-ray from the front-end | tip part and side part of the ultraviolet irradiation part 14, the cone shape which has a some step | paragraph is mentioned, for example. Or it is a bundle | flux of several optical fibers, Comprising: The terminal may be cut | disconnected in a different position, respectively, and you may have step shape.

  Or the ultraviolet irradiation part 14 may be only the terminal part of the front-end | tip of the pulp cavity insertion plug 13. FIG. For example, it may be a cut surface at the end of the optical fiber. In this case, for example, by mounting the detachable chip made of a material capable of scattering ultraviolet rays on the ultraviolet irradiation unit 14, it is possible to irradiate ultraviolet rays at a wide angle.

  The ultraviolet irradiation section 14 provided at the distal end portion of the dental pulp cavity plug 13 has an outer diameter smaller than the diameter of the dental pulp cavity (usually 3 mm or less). Since the ultraviolet irradiation is not performed in direct contact with the dentin, the outer diameter thereof is preferably 1 mm to 2 mm in consideration of the distance between the ultraviolet irradiation section 14 and the dentin. Moreover, it is preferable that the ultraviolet irradiation part 14 which can irradiate an ultraviolet-ray from a side part has a length substantially equivalent to the depth of a dental pulp cavity. For example, in order not to irradiate ultraviolet rays in the oral cavity other than the pulp cavity, it is preferable that the length is shorter than 19 mm, for example, 10 to 15 mm, comparable to the distance from the crown surface to the pulp cavity bottom.

  Moreover, the ultraviolet irradiation part 14 is not limited to one. For example, in the case of a molar tooth, the pulp cavity is divided into three parts, so that three ultraviolet irradiation units 14 may be provided accordingly. Alternatively, one to three ultraviolet irradiation units 14 may be detachably mounted at the distal end of the dental pulp cavity plug 13.

  Although the ultraviolet light source 15 is not specifically limited, A low pressure mercury lamp, a high pressure mercury lamp, a metal halide lamp, a mercury xenon lamp, a light emitting diode etc. are mentioned. Long life, no variation in light quantity, easy to control temperature and heat, no harmful substances such as mercury are used, it is environmentally friendly, no filter for removing unnecessary wavelength light (for example, UV spectroscopic lens), and small size An ultraviolet light-emitting diode (UV-LED) is preferable in that it can be made.

  The ultraviolet light source 15 is not necessarily arranged in the handpiece unit 11 as illustrated in FIG. 1, and may be provided in the control device 20. In that case, the ultraviolet light emitted from the ultraviolet light source 15 is transmitted from the control device 20 to the ultraviolet irradiation unit 14 by an optical fiber or the like.

  The ultraviolet light emitted from the ultraviolet light source 15 preferably has a wavelength of 320 nm to 400 nm, generally referred to as UV-A. More preferably, it is 360 nm-400 nm. Ultraviolet light having a wavelength of less than 320 nm is not preferable because it has a sunburn effect, has a strong bactericidal action, and is highly destructive to living bodies. The output of such ultraviolet rays is controlled by output control means 22 provided in the control device 20.

  The irradiation switch 16 is a switch that is provided outside the handle portion 11 and causes the ultraviolet light source 15 to emit light. Since the irradiation switch 16 is provided on the handle portion 11 held by the user, the user can easily perform the ultraviolet irradiation operation at the time of use. The irradiation switch 16 is connected to an energization switch 21 provided in the control device 20, and this energization switch 21 is connected to the ultraviolet light source 15 via an output control means 22. For example, when the irradiation switch 16 is turned on at the start of use, the ultraviolet light source 15 is connected to the power source and the ultraviolet irradiation is started. On the other hand, when the irradiation switch 16 is turned off, the connection with the power source is cut off and the ultraviolet irradiation is stopped.

  As shown in FIG. 1, the control device 20 includes an energization switch 21 and an output control means 22.

  The energization switch 21 is connected such that the supply of electricity to the ultraviolet light source 15 can be controlled by the output control means 22. The energization switch 21 controls the supply of electricity to the ultraviolet light source 15 from a power source (outlet) or a battery (located in the control device 20 as necessary). The intensity of the ultraviolet light is substantially proportional to the amount of current that is passed through the ultraviolet light source 15.

  Although the output control means 22 is not shown in order to control the ultraviolet irradiation time, for example, a timer may be provided. The timer operates to automatically turn off the irradiation switch 16 at a set time, for example.

  The control device 20 is further provided with components included in a general output adjustment device such as a DC amplifier and a DC converter. If a battery is installed, it can be carried.

  Next, the usage method of the dental apparatus 1 of this invention shown in FIG. 1 is demonstrated. First, the dental apparatus 1 of the present invention is connected to a power source (outlet) or a battery and energized to make the dental apparatus 1 usable. Next, an output of ultraviolet rays emitted from the ultraviolet light source 15 is set by output setting means (not shown) provided in the output control means 22.

The set output varies depending on the wavelength used, but is preferably at least 500 mW / cm ² . More preferably 800~3200mW / cm ^2, more preferably and particularly preferably at 1000~2500mW / cm ² is 1200~2000mW / cm ^2. When the output is less than 500 mW / cm ² , the ultraviolet irradiation time necessary for imparting sufficient strength to the dentin becomes long, which is not preferable. On the other hand, when the output is large, for example, when it is larger than 4000 mW / cm ² , there is a possibility that the temperature of the irradiated part will excessively increase, and that the collagen constituting the dentin may be destroyed. Therefore, it is not suitable. When the output control means 22 is provided with a timer, an ultraviolet irradiation time described in detail below may be set in advance as necessary.

  Next, the handle portion 11 of the handpiece portion 10 is held, and the pulp cavity insertion plug 13 is inserted into the pulp cavity. At this time, the ultraviolet irradiation part 14 provided in the pulp cavity insertion plug 13 is arranged so that the entire dentin exposed to the pulp cavity can be irradiated.

  Next, by turning on the irradiation switch 16 of the handpiece unit 10, an electric current is passed through the ultraviolet light source 15, and ultraviolet rays are irradiated from the ultraviolet irradiation unit 14 onto the dentin. In order to uniformly irradiate the dentin, the position of the pulp cavity insertion plug 13 in the pulp cavity may be moved as necessary.

  The time for irradiating ultraviolet rays varies depending on the output or the type and size of the teeth. Usually, it is 30 seconds to 30 minutes, preferably 1 to 20 minutes, more preferably 5 to 15 minutes.

  After irradiating with ultraviolet rays for a desired time, the irradiation switch 16 of the handpiece unit 10 is turned off to terminate the ultraviolet irradiation. Thereafter, the dental pulp cavity plug 13 is removed from the dental pulp cavity and withdrawn from the oral cavity.

  As described above, the tooth from which the pulp has been removed can be mechanically strengthened by irradiating the dentin with ultraviolet rays using the dental apparatus 1 of the present invention. The apparatus of the present invention is preferably used as a method for strengthening teeth by ultraviolet irradiation. However, as long as the dentin can be irradiated with ultraviolet rays, other apparatuses and / or means may be used for ultraviolet irradiation. May be.

  Hereinafter, the principle of the tooth strengthening method using the dental apparatus of the present invention will be described with reference to examples.

(Preparation of rod-shaped sample)
In the examples, a low-speed precision cutter (ISOMET2000: BUEHLER) and a rotary polisher (ECOMET III: BUEHLER) from the dentin at the center of the occlusal surface of the third extracted molar without caries and fracture. Two types of 0.9 × 1.6 × 8.0 mm dentin rod-shaped samples having a major axis in the direction parallel to and perpendicular to the dentinal tubule running direction were collected.

(Example 1: Examination of bending strength by ultraviolet irradiation)
For the above rod-shaped sample, using an LED ultraviolet irradiator (ZUV-C30H: OMRON Corporation) at a wavelength of 365 nm and an output of 800, 1200, 1600, or 3200 mW / cm ² for 5 minutes, 15 minutes, or Ultraviolet irradiation was performed for 30 minutes at an irradiation distance of 10 mm.

  The dimensions of the sample before and after the ultraviolet irradiation treatment were measured with a precision of a minimum display amount of 0.001 mm using a digital caliper (IP54: Mitutoyo Corporation), and the linear shrinkage rate was calculated. About 0.4% linear shrinkage was observed by UV irradiation (data not shown). This was a smaller shrinkage than the heat treatment at 110 ° C. and 140 ° C. (about 2%).

  After ultraviolet irradiation, a cantilever bending test was performed using a universal mechanical strength tester (Autograph AG-IS; Shimadzu Corporation) in the room temperature atmosphere. Specifically, the sample after the ultraviolet irradiation is mounted on a metal jig, held 2 mm from the end of the rod-shaped sample, and 2 mm from the held position (that is, holding the rod-shaped sample). A breaking load was applied at a crosshead speed of 0.1 mm / second to a position 4 mm from the end on the formed side, and the breaking load at the yield point was measured. Measurements were made on 10-15 samples for each of the above conditions. FIG. 2 shows the result of the breaking load at the yield point.

As can be seen from FIG. 2, at any output, the bending strength of the dentin was improved by the ultraviolet irradiation. In particular, in the case of 1200 and 1600 mW / cm ² , the bending strength was improved about twice as much as that before the treatment by irradiation for 5 to 15 minutes. Therefore, it was found that the mechanical strength of dentin is improved by ultraviolet irradiation.

(Example 2: Examination of dentin surface temperature by ultraviolet irradiation)
Using the LED ultraviolet irradiator (ZUV-C30H: OMRON Corporation), the above bar-shaped sample was irradiated with ultraviolet rays at an irradiation distance of 10 mm under a wavelength of 365 nm and an output of 800, 1200, 1600, or 3200 mW / cm ^2. Irradiation was performed. The surface temperature of the sample was measured at 5 minutes, 10 minutes, and 30 minutes after the start of ultraviolet irradiation. The results are shown in Table 1.

  As can be seen from Table 1, the surface temperature gradually increased according to the irradiation power and time. However, the temperature was sufficiently lower than the heating temperature (70 ° C. to 140 ° C .: Patent Document 1 and Non-Patent Document 8) known to be effective in improving the mechanical strength of the teeth. From this, it was found that the improvement in dentin strength by ultraviolet irradiation was not caused by heating.

(Example 3: Examination of bending strength by re-immersion after UV irradiation)
For the above rod-shaped sample (n = 10), using an LED ultraviolet ray irradiator (ZUV-C30H: OMRON Corporation) at a wavelength of 365 nm and an output of 3200 mW / cm ² for 5 minutes or 15 Ultraviolet irradiation was performed for a minute. After the ultraviolet irradiation, it was immersed in Hanks balanced salt solution (HBSS: Sigma Aldrich Japan Co., Ltd.) at 37 ° C. for 3 days or 7 days. After immersion, a cantilever bending test was performed in the same manner as in Example 1. Moreover, the dimension of the sample was measured similarly to the said Example 1, and the linear shrinkage rate was computed. The results are shown in FIG. In FIG. 3, the bar graph (left vertical axis) represents the bending strength, and the line graph (right vertical axis) represents the linear shrinkage rate.

  As can be seen from FIG. 3, when the dentin was irradiated with ultraviolet rays, the bending strength obtained by the ultraviolet irradiation was maintained even after being immersed in HBSS. In addition, in the sample heat-processed at 140 degreeC, when it immersed in HBSS, the bending strength of dentin returned almost the same as before heating (data not shown). Therefore, it was found that the improvement of dentin strength by ultraviolet irradiation is different from the improvement of strength by heating.

  In addition, it was found that the linear shrinkage caused by the ultraviolet irradiation completely returned to the pre-immersion by immersion in HBSS.

(Example 4: Examination of distance between collagen molecules by X-ray diffraction measurement after ultraviolet irradiation)
A rod-shaped sample of 0.5 × 0.3 × 3.0 mm in which the running direction of the dentinal tubule is perpendicular to the long axis of the sample is stored in 0.5 M EDTA at 23 ° C. for 7 days. Then, hydroxyapatite decalcification treatment was performed. After deashing, ultraviolet irradiation was performed for 5 minutes at an irradiation distance of 10 mm under the conditions of a wavelength of 365 nm and an output of 3200 mW / cm ² . Next, using an imaging plate X-ray detector (RAXIS-IV: Rigaku Co.) equipped with a rotating anti-cathode X-ray generator (ultraX18: Rigaku Co.), output: 50 kV, 250 mA, X-ray source: CuKα The intermolecular distance of collagen was measured in vacuum at room temperature using a line, beam size: 0.3 mm, and camera length: 150 to 300 mm. Moreover, the intermolecular distance of collagen was similarly measured about the sample immersed in HBSS over 7 days after ultraviolet irradiation.

  For comparison, the intermolecular distance of collagen was also measured by X-ray diffraction measurement for a wet sample before decalcification treatment and a sample heated to 140 ° C. using an oven (KL100: Kuraray Medical Co., Ltd.). . The results are shown in Table 2.

  As a result of analyzing the orientation of collagen molecules by X-ray diffraction, the distance between collagen molecules before ultraviolet light or heat treatment was 13.6 mm. The distance between collagen molecules contracted to about 10.6 to 10.8 cm by ultraviolet irradiation and heat treatment. This shrinkage was found to be almost completely restored to the pre-treatment state by immersion in HBSS for 7 days in the case of heat treatment, but not completely in the case of ultraviolet treatment. Thus, in the sample after ultraviolet irradiation, after the immersion in HBSS, the linear shrinkage rate was restored as apparent from the results of Example 3 above, whereas the collagen intermolecular distance was not restored. .

(Example 5: Quantification of cross-linking between collagen molecules after ultraviolet irradiation)
The crown and dentin were frozen and pulverized with liquid nitrogen, and then irradiated with ultraviolet rays for 5 minutes at an irradiation distance of 10 mm under conditions of a wavelength of 365 nm and an output of 3200 mW / cm ² . After the ultraviolet irradiation, the sample was stored in 0.5 M EDTA at 23 ° C. for 7 days to perform a hydroxyapatite decalcification treatment. After decalcification, reduction of the immature crosslinkable reductive bridges (dihydroxylydinonorleucine and hydroxylydinonorleucine) and tritium labeling were carried out with tritium-labeled sodium borohydride. Next, after hydrolysis using 6N hydrochloric acid, collagen intermolecular crosslinking was quantified using cation exchange high performance liquid chromatography (DGU20A3: Shimadzu Corporation). Non-reducing bridges (pyridinoline and deoxypyridinoline) and aging bridges (pentosidine), which are mature bridges, were fluorimetrically determined using the properties of natural fluorescence. The results are shown in FIG.

  As can be seen from FIG. 4, by UV irradiation, the non-reducing cross-linkage that is a mature cross-linkage is about 20% from 0.20 mol / mol collagen to 0.04 mol / mol collagen before UV irradiation, and pentosidine that is an aging cross-link. Decreased from 2.46 mol / mol collagen to 1.68 mol / mol collagen to about 70%. It is known that a decrease in mature cross-linking leads to a decrease in mechanical strength (L. Knott et al., Bone, 22: 181-187, 1998), but a decrease in aging cross-linking increases mechanical strength. It is thought that had influenced.

(Example 6: Analysis of collagen molecular structure change after ultraviolet irradiation by micro-infrared spectroscopy)
A thin slice of about 20 μm in thickness was collected from the coronal dentin and stored in 0.5 M EDTA at 23 ° C. for 7 days for hydroxyapatite decalcification. After decalcification, UV irradiation was performed for 3 minutes, 5 minutes, 10 minutes, and 15 minutes at an irradiation distance of 10 mm under the conditions of a wavelength of 365 nm and an output of 3200 mW / cm ² . The sample was analyzed using a micro-infrared spectrometer (FTIR620 + IRT30: JASCO Corporation) under the conditions of a resolution of 4 cm ⁻¹ , an integration count of 100 times, a scan speed of 4 mm / second, and a measurement area of 200 × 200 μm ² .

  The amide bond has a reference vibration called amides I, II, and III, as shown at the top of FIG. Of these, amide I has a strong property of C═O stretching vibration. On the other hand, amides II and III have a hybrid mode of CN stretching vibration and NH in-plane bending vibration. The measurement results were analyzed by paying attention to the spectra of these amides I, II, and III that define the planar structure of the polypeptide. The obtained infrared absorption spectrum is shown in the lower part of FIG. In the spectrum diagram of FIG. 5, the results of the untreated, 3 minute irradiated, 5 minute irradiated, 10 minute irradiated and 15 minute irradiated samples are shown in order from the top.

The attenuation of the height peak due to dehydration near 3300 cm ⁻¹ seen in the heated sample was not seen in the UV irradiated sample. Moreover, a large change in the primary structure, such as the amide I (1650 cm ^-1) and amide II (1540 cm ^-1) were observed.

(Example 7: Analysis of changes in collagen molecular structure after ultraviolet irradiation by microscopic laser Raman spectroscopy)
A thin slice of about 20 μm in thickness was collected from the coronal dentin and stored in 0.5 M EDTA at 23 ° C. for 7 days for hydroxyapatite decalcification. After decalcification, ultraviolet irradiation was performed for 3 minutes, 5 minutes, and 15 minutes at an irradiation distance of 10 mm under the conditions of a wavelength of 365 nm and an output of 3200 mW / cm ² . Using a microscopic laser Raman spectroscopic analyzer (RAMAN-11: Nanophoton Co., Ltd.) as a sample, the laser was 785 nm long, the resolution was 2 cm ⁻¹ , the measurement time was 180 seconds, and the measurement area was 1.0 × 1.0 μm ² . Analyzed with The obtained Raman spectrum is shown in FIG. In FIG. 6, the results of the untreated sample, 3 minute irradiation, 5 minute irradiation, and 15 minute irradiation sample are shown in order from the top.

Amplification of the peak height of 922 cm ⁻¹ , which is considered to be a carbon-carbon bond of proline, and amplification of peaks of 1323, 1407, and 1453 cm ⁻¹ were observed, suggesting a change in the collagen molecular structure. From this, not only the shrinkage of the distance between collagen molecules due to dehydration but also the decrease in collagen mature and aging crosslinks due to dehydration, and changes in the molecular structure of the collagen due to Raman spectroscopic analysis may occur. all right. It is suggested that such chemical change of collagen is involved in maintaining the strength of dentin when immersed in HBSS. Therefore, it is considered that ultraviolet irradiation is more suitable for improving the dentin mechanical strength than heat treatment.

  ADVANTAGE OF THE INVENTION According to this invention, the dental apparatus which can reinforce the tooth | gear from which the pulp was removed safely and effectively is provided. Thus, the device of the present invention is useful for strengthening teeth from which the pulp has been removed. By using the apparatus of the present invention, it is possible to easily reinforce a tooth that has become brittle by removing the pulp by treatment such as caries, and the health of the tooth that has lost the pulp over a longer period of time can be maintained. Therefore, it leads to improvement of QOL. In addition, if the device of the present invention becomes widespread, it can avoid a fatal failure in dental treatment, such as a tooth fracture, and it can also reduce the medical cost required for redoing the filling that accounts for the majority of today's dental treatment. Connected.

DESCRIPTION OF SYMBOLS 1 Dental apparatus 10 Handpiece part 11 Handle part 12 Protective tube 13 Pulp cavity plug 14 Ultraviolet irradiation part 15 Ultraviolet light source 16 Irradiation switch 20 Control device 21 Current supply switch 22 Output control means 30 Connection part

Claims (9)

  A dental apparatus for mechanically strengthening a tooth from which a pulp has been removed, comprising a handpiece part and a control device, wherein the handpiece part inserts a pulp cavity for irradiating ultraviolet rays onto the dentin of the tooth A dental apparatus comprising a plug and an ultraviolet light source, and the pulp cavity plug has an ultraviolet irradiation part.   The dental apparatus according to claim 1, wherein the ultraviolet irradiation unit has a length substantially equal to a depth of a dental pulp cavity.   The dental apparatus according to claim 1 or 2, wherein in the ultraviolet irradiation unit, ultraviolet rays are irradiated from a front end portion and a side surface portion thereof.   The dental apparatus according to any one of claims 1 to 3, wherein the ultraviolet irradiation unit has a conical shape having a plurality of steps.   The dental apparatus according to any one of claims 1 to 4, wherein the ultraviolet irradiation unit includes a chip that covers the ultraviolet irradiation unit and is detachable.   The dental apparatus according to claim 5, wherein the tip is capable of irradiating by scattering ultraviolet rays.   The dental apparatus according to any one of claims 1 to 6, wherein the ultraviolet ray has a wavelength of 320 nm to 400 nm.   The dental apparatus according to any one of claims 1 to 7, wherein the ultraviolet light source is an ultraviolet light emitting diode.   The dental apparatus according to any one of claims 1 to 8, comprising output control means for the ultraviolet light source.

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