JP2005160598A - Method and apparatus for tooth shape measurement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for tooth shape measurement, which greatly reduces the number of times of taking an impression, improves a reproduction precision of a deficiency part model and reduces the workload of a dentist by directly measuring a female model by a dentist as a deficiency part model. <P>SOLUTION: A dental impression material having a low laser transmittance and a little contractive deformation is prepared, the female model fitted to the tooth shape is made from the tooth of a patient using a dental impression material, and the external shape of the female model is measured by a triangulation method using a laser. A main component of the dental impression material is natural wax and the material includes fine particles causing diffuse-reflection, when irradiated with the laser beam. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a tooth shape measuring method and apparatus for measuring a three-dimensional shape of a tooth defect portion.

  In a dental treatment, when a defect portion is formed in a tooth due to caries or the like, a treatment is generally performed in which the defect portion is covered with a prosthesis made of metal or ceramic and fixed.

  In order to manufacture such a dental prosthesis, it is necessary to manufacture a model of a tooth defect portion from an impression mold of the tooth defect portion and accurately measure the three-dimensional shape thereof. For this reason, a non-contact type three-dimensional shape measuring means using laser light is disclosed.

FIG. 3 is a principle diagram of such a non-contact type three-dimensional shape measuring means. In this figure, M is a tooth model, 51 is a laser light source for irradiating laser light 51a, 52 is a condenser lens, 53 is a light position detecting element (PSD), and laser light is directed toward a measurement point P of the tooth model M. 51a is irradiated, the reflected light 51b from the tooth model M is condensed on the PSD 53, and the position y is detected.
With this configuration, the incident angle α of the reflected light is geometrically determined from the light receiving position y of the PSD 53 and the irradiation angle θ of the laser beam 51a, and the distance L between the measurement point P and the sensor reference point Ps is repeatedly calculated from these. The three-dimensional shape of the tooth model M can be specified. However, in the case of three-dimensional shape measurement provided with only a single light position detection element, depending on the shape of the object to be measured (tooth model M), the primary reflected light does not enter and measurement cannot be performed. There is.

  On the other hand, the “three-dimensional shape measuring method and apparatus” of Patent Document 1 includes at least two or more combinations of lenses and optical position detection elements as shown in FIG. Even if no reflected light is incident on the position detection elements (for example, 53c and 53d), the reflected light is incident on the remaining light position detection elements (for example, 53a and 53b), so that measurement is performed regardless of the shape of the object to be measured. be able to.

  In addition, if the object to be measured (dental model) has a complicated three-dimensional shape with a recess in the center of the upper part, the laser beam is not measured even if the measurement site is not irradiated with the laser or the laser is irradiated. Patent Document 2 has been proposed because it is blocked by an object and cannot receive light.

  As shown in FIG. 5, the “three-dimensional shape measuring apparatus and method” of Patent Document 2 holds a device under test M, and holds the device under test around a plurality of vertical axes z1 and z2 passing therethrough. A rotating device 62, a plurality of optical position detecting elements 64 and 66) that receive reflected light from the object to be measured, and a laser device that is positioned between the plurality of optical position detecting elements and scans the laser light toward the object to be measured. 68, an arithmetic unit for calculating a plurality of shape measurement data groups of the object to be measured on a plurality of vertical axes z1 and z2 from the scanning direction of the laser beam and the light receiving positions of the reflected light of the laser beam by the plurality of optical position detection elements 70 and interpolation means 72 for interpolating the blind spot from a plurality of shape measurement data groups.

JP-A-9-42941 Japanese Patent Application No. 2003-047326, unpublished

  For example, in a dental treatment, when a defect portion that is dented with caries or the like is formed in the upper central portion of the tooth, a treatment is generally performed in which a filling called an inlay is inserted into the defect portion. In this case, in order to measure the shape of the defect part, conventionally, (1) First, a dentist made a female model (having a recess corresponding to a tooth) using a dental impression agent from a patient's teeth, 2) Next, a male model (having a convex portion corresponding to a tooth) is produced from this female model with plaster and the like. (3) Based on this male model, a dental technician uses a lost wax method or the like. A defect part model having the same shape as the female model was made of resin or the like, and (4) the three-dimensional shape was measured by the conventional means described above.

  However, an alginate impression material (also referred to as an alginate impression material) that is usually used as a dental impression agent is harmless to the human body because it is extracted from natural seaweed, but it has the drawback of shrinking and changing its shape in a short time. . Therefore, it is necessary to produce a defect model with gypsum immediately after producing a female model using an alginate impression material, which is a time-consuming work for the dentist, which is a heavy burden.

  In addition, although a female model is made by using silicon rubber instead of an alginate impression material, since silicon rubber has low moldability, there is a problem that a complicated three-dimensional shape cannot be reproduced.

Furthermore, since the production of a hard model by the lost wax method is usually performed by a dental technician's technical work, it takes time and labor, and this is a factor in prolonging the treatment.
In addition, since the defect part model (resin, etc.) is manufactured from the patient's teeth via the female model (dental impression agent) and the male model (gypsum), the number of molds is large and the reproduction accuracy of the defect part model is reduced. There was a problem to do.

  The present invention has been developed to solve the above-described problems. That is, the purpose of the present invention is to directly measure the female model by the dentist as a missing part model, thereby greatly reducing the number of molds taken, can increase the reproduction accuracy of the missing part model, And it is providing the tooth shape measuring method and apparatus which can reduce the work burden of a dentist.

  According to the present invention, a dental impression material having a low laser transmittance and low shrinkage deformation is prepared, and a female model that fits into a tooth shape from a patient's tooth is manufactured using the dental impression material. There is provided a tooth shape measuring method characterized by measuring the outer shape of a female model by a triangulation method using a laser.

  According to a preferred embodiment of the present invention, the dental impression material contains natural wax as a main component and contains fine particles that diffusely reflect when irradiated with laser light. The fine particles are any of titanium oxide, calcium carbonate, barium sulfate, silica particles, or a mixture thereof. The dental impression material contains 3% by weight or more and less than 6% by weight of fine particles having an average particle diameter of 1 nm to 1 μm.

  Further, according to the present invention, the elongated model holding rod that holds the object to be measured fitted into the tooth shape at the tip, the rod holder that holds the end of the model holding rod, and the model holding rod horizontally A model positioning jig composed of a support base that can be held and fixed in the upside down position, and the model positioning jig is fixed to the upper surface and the object to be measured is rotated around a vertical axis that is at least close to the object to be measured. Holding and rotating device, a plurality of optical position detection elements that receive reflected light from the object to be measured, a laser device that is positioned between the plurality of optical position detection elements and that scans the laser light toward the object to be measured; A tooth shape measuring apparatus comprising: an arithmetic device that calculates a shape measurement of an object to be measured from a scanning direction of laser light and light receiving positions of reflected light of the laser light by the plurality of optical position detecting elements. Provided.

  According to a preferred embodiment of the present invention, the object to be measured is made of a dental impression material having a natural wax as a main component and low laser transmittance and little shrinkage deformation, and the tip of the model holding rod is in the axial direction. The rod holder is fixed to the end of the model holding rod.The rod holding tool is fixed to the end of the model holding rod. A cylindrical portion that holds the cylindrical portion and a suction surface orthogonal to the axis of the model holding rod, and the support base has a semicircular arc inner surface that holds the cylindrical portion and a vertical surface that faces the suction surface. The rod holder and the support base have a positioning concave hole on the suction surface and the vertical surface, and a positioning ball is inserted into the concave hole. Adsorb the holder toward the support base That includes a magnet.

According to the method of the present invention, a female model that fits into a tooth shape from a patient's teeth is manufactured, and the outer shape of this female model is measured by a triangulation method using a laser. Can be reduced to one time to increase the reproduction accuracy of the defect model.
Further, since a dental impression material having a low laser transmittance and a small amount of shrinkage deformation is used, there is no time-consuming work for the dentist, and the burden can be greatly reduced.

  Further, by using the dental impression material having the above-described configuration, natural wax is harmless to the human body and has high moldability as in the conventional lost wax method, and can accurately reproduce complicated three-dimensional shapes. In addition, natural wax itself is a translucent material and cannot be applied to a triangulation method using a laser because laser light enters the inside, but fine particles (for example, titanium oxide, calcium carbonate) that diffusely reflect when irradiated with laser light. By mixing 3% by weight or more of barium sulfate or silica particles), it is possible to eliminate the internal penetration of laser light without impairing moldability. It has been confirmed by experiments that mixing 6 wt% or more of titanium oxide makes it difficult to mix with the wax material and deteriorates the moldability.

  In addition, with the configuration of the tooth shape measuring device, the object to be measured that fits in the tooth shape is held at the tip of the elongated model holding rod, the end of the model holding rod is held by the rod holder, and the model is held by the support base. By holding the holding rod horizontally and fixing it to the upside down position, it is possible to accurately position the object to be measured and fix it at the upside down position for accurate shape measurement.

Also, with this configuration, the object to be measured is a cylindrical material having natural wax as a main component, a dental impression material with low laser transmittance and low shrinkage deformation, and the tip of the model holding rod having a slit or surface in the axial direction. Since it has a shape, it is possible to fix the object to be measured without deforming the outer shape of the object to be measured by heating and inserting the tip portion.
Moreover, since the rod holder has a cylindrical portion that holds the end portion of the model holding rod, and the support base has a semicircular inner surface that holds the cylindrical portion, the model holding rod is held horizontally by fitting them. can do.
Further, since the rod holder has a suction surface orthogonal to the axis of the model holding rod, and the support base has a vertical surface opposite to the suction surface, the rod holder is supported by a magnet attached to the support base. By adsorbing toward the surface, the horizontal holding accuracy of the model holding rod can be further increased.
In addition, the rod holder and the support base have a concave hole for positioning on the suction surface and the vertical surface, and a positioning ball is inserted in the concave hole, so that the object to be measured is accurately positioned, And this can be fixed to the upside down position and accurate shape measurement can be performed.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

  Natural wax is harmless to the human body and has high moldability like the conventional lost wax method, and can accurately reproduce complex three-dimensional shapes. However, natural wax itself is a translucent body, and laser light penetrates into the inside, so that it cannot be applied to a triangulation method using a laser.

  Thus, the inventors of the present invention tried to reduce the internal penetration of laser light by mixing titanium oxide with natural wax, and obtained the results shown in Table 1.

  As can be seen from Table 1, it was confirmed that the internal penetration of the laser beam could be eliminated without impairing the moldability by mixing 3% by weight or more of titanium oxide. Further, it was confirmed that when titanium oxide was mixed by 6% by weight or more, mixing with the wax material was difficult and the moldability deteriorated. The titanium oxide used had an average particle size of 1 nm to 1 μm. The mixed particles may be particles selected from titanium oxide, calcium carbonate, barium sulfate, silica particles, or a mixture thereof.

  The method of the present invention is based on the new findings obtained in this experiment. That is, according to the tooth shape measuring method of the present invention, (1) first, a dental impression material with low laser transmittance and low shrinkage deformation is prepared, and (2) using this dental impression material, from the patient's teeth. A female model that fits into the tooth shape is manufactured. (3) Next, the external shape of the female model is measured by a triangulation method using a laser.

  As shown in Table 1, it is preferable to use a dental impression material containing natural wax as a main component and titanium oxide having an average particle diameter of 1 nm to 1 μm in an amount of 3 wt% or more and less than 6 wt%.

According to the above-described method of the present invention, a female model that fits a tooth shape from a patient's teeth is manufactured, and the outer shape of the female model is measured by a triangulation method using a laser. By reducing the number of times to one, the reproduction accuracy of the defect model can be increased.
Further, since a dental impression material having a low laser transmittance and a small amount of shrinkage deformation is used, there is no time-consuming work for the dentist, and the burden can be greatly reduced.

FIG. 1 is an overall configuration diagram of a tooth shape measuring apparatus according to the present invention. This apparatus is optimized for shape measurement of a female model (mainly composed of natural wax) obtained by the method described above.
In other words, the tooth shape measuring device 20 includes a model positioning jig 10, a holding and rotating device 22, an optical position detecting element 24, a laser device 26, and an arithmetic device 28.

The model positioning jig 10 has a function of holding the object to be measured M horizontally and positioning it upside down around a horizontal axis x passing through the origin indicated by O in the drawing. The structure of the model positioning jig 10 will be described later.
The holding and rotating device 22 fixes the model positioning jig 10 on the upper surface, and rotates the measurement object M around the vertical axis z that is at least close to the measurement object M. By rotating the device under test M once around the vertical axis z, the entire outer surface of the device under test M can be measured.
Note that the model positioning jig 10 may be fixed to the holding / rotating device 22 by suction with a magnet or by fitting a pin and a pin hole.

In this example, two optical position detecting elements 24 are provided on the upper and lower sides, and receive the reflected light 2 from the object M to be measured.
The laser device 26 includes a laser oscillator 26 a and a scanning mirror 26 b, is positioned between the two optical position detection elements 24, and scans the laser beam 1 toward the object M to be measured. The laser oscillator 26a preferably irradiates laser light 1 having a single wavelength toward the scanning mirror 26b. The scanning mirror 26b is swung by a drive device (not shown), reflects the laser beam 1 and scans the laser beam 1 toward the object M to be measured.

The calculation device 28 calculates the shape measurement of the object M from the scanning direction of the laser beam 1 and the light receiving position of the reflected light 2 of the laser beam by the two light position detecting elements 24.
In this example, the laser light 1 from the first and second optical position detection elements 24 and the laser device 26 is preferably in the same plane that passes through the object M (in this example, the first quadrant of the xz coordinate). The three-dimensional shape measurement of the outer surface of the object to be measured M is made possible by the two-dimensional measurement of the xz coordinate and the rotation of the object to be measured M around the z axis.

Further, when the signal output of any of the plurality of light position detection elements 24 is weak (less than a predetermined value), the low signal output is ignored and the laser light irradiation position P is calculated from the strong signal output. Thereby, an error due to a weak signal can be prevented.
Note that a computer (for example, a personal computer) can be used as the arithmetic unit 28.

FIG. 2 is a configuration diagram of the model positioning jig of FIG. In this figure, (A) is a side view, (B) is a cross-sectional view taken along line BB, and (C) is a view taken along the line CC.
As shown in FIG. 2, the model positioning jig 10 includes a model holding rod 12, a rod holder 14, and a support base 16.

The model holding rod 12 is an elongated rod-like member, and has a function of holding the object to be measured M that fits in a tooth shape at the tip. As described above, the object to be measured M is made of a dental impression material containing natural wax as a main component, low laser transmittance, and little shrinkage deformation.
The tip end portion (left end portion in the figure) of the model holding rod 12 has a cylindrical shape having a slit or a surface in the axial direction, and this portion is heated and then inserted into the end portion of the subject M to be measured. The object to be measured M is fixed without deforming the outer shape of the. In this case, the end portion of the object to be measured M is preferably a non-measurement portion that does not fit directly into the tooth shape of the patient.

  The rod holder 14 includes a cylindrical portion 14 a that holds the end portion of the model holding rod 12 and a suction surface 14 b that is orthogonal to the axis of the model holding rod 12, and holds the end portion of the model holding rod 12 horizontally. It is supposed to do.

  The support 16 has a semicircular arc inner surface 16a that holds the cylindrical portion 14a of the rod holder 14 and a vertical surface 16b that faces the suction surface 14b of the rod holder 14, and holds the model holding rod 12 horizontally. And this can be fixed to the upside down position.

As shown in FIG. 2 (B), the rod holder 14 and the support base 16 have concave holes 14c and 16c for positioning on the suction surface 14b and the vertical surface 16b, and are positioned in the concave holes 14c and 16c. A ball 19 is inserted.
Furthermore, a magnet 18 (magnet) is attached to the opposite side of the vertical surface 16 b of the support base 16, and the suction surface 14 b of the rod holder 14 is attracted toward the vertical surface 16 b of the support base 16. In addition, by this adsorption | suction, although the adsorption | suction surface 14b is adsorb | sucked to the vertical surface 16b, it is not necessary to adhere | attach completely, and there may be a clearance gap slightly by the ball | bowl 20 which intervenes.

  Due to the configuration of the model positioning jig 10 described above, the object to be measured M is made of a dental impression material containing natural wax as a main component, low laser transmittance, and little shrinkage deformation, and the tip of the model holding rod 12 has a shaft. Since it has a cylindrical shape having a slit or a surface in the direction, the object to be measured can be fixed without deforming the outer shape of the object to be measured M by inserting the tip portion by heating.

  Further, since the rod holder 14 has a cylindrical portion 14a for holding the end portion of the model holding rod 12, and the support base 16 has a semicircular arc inner surface 16a for holding the cylindrical portion, the model holding is achieved by fitting them. The rod 12 can be held horizontally. Further, as shown in FIG. 2C, the notch 16d is provided on the side surface of the semicircular arc inner surface 16a, so that the rod holder 14 can be easily removed together with the model holding rod 12. Therefore, when the female model M that fits into the tooth shape from the patient's teeth is manufactured, the female model is mainly composed of natural wax and may be easily deformed by an external force. It is good to fix to the front-end | tip part of the model holding rod 12 attached to the rod holder 14.

Further, since the rod holder 14 has a suction surface 14b orthogonal to the axis x of the model holding rod 12, and the support base 16 has a vertical surface 16b opposite to the suction surface 14b, it is attached to the support base 16. By attracting the rod holder 14 toward the support 16 with the magnet 18, the accuracy of the horizontal holding of the model holding rod 12 can be further increased.
Further, since the rod holder 14 and the support base 16 have a concave hole for positioning on the suction surface and the vertical surface, and a positioning ball is inserted into the concave hole, the object to be measured is accurately positioned. In addition, it is possible to perform accurate shape measurement by fixing it at the upside down position.

  Therefore, with the configuration described above, the object to be measured M to be fitted in a tooth shape is held at the tip of the elongated model holding rod 12, the end of the model holding rod 12 is held by the rod holder 10, and the model is supported by the support base. By holding the holding rod horizontally and fixing it to the upside down position, it is possible to accurately position the object to be measured and fix it at the upside down position for accurate shape measurement.

  In addition, this invention is not limited to the Example and embodiment mentioned above, Of course, it can change variously in the range which does not deviate from the summary of this invention. For example, although the inlay tooth model which has a recessed part in the upper center is assumed as the to-be-measured object M in the example mentioned above, this invention is not limited to this, It applies similarly to an abutment tooth and other tooth models. be able to.

  As described above, the tooth shape measuring method and apparatus of the present invention can directly measure a female model by a dentist as a missing part model, thereby greatly reducing the number of molds taken, The reproducibility can be improved and the work load on the dentist can be reduced.

It is a whole block diagram of the tooth shape measuring apparatus of this invention. It is a block diagram of the model positioning jig of FIG. It is a principle figure of the optical position detection element used by this invention. It is a principle diagram of a non-contact type three-dimensional shape measuring means. It is explanatory drawing of the three-dimensional shape measurement means of a prior application.

Explanation of symbols

1 laser light, 2 reflected light, 10 model positioning jig,
12 model holding rod, 14 rod holder,
14a cylindrical part, 14b adsorption surface,
16 support base, 16a semicircular arc inner surface, 16b vertical surface,
14c, 16c recessed hole, 16d notch,
18 magnets, 19 balls,
20 tooth shape measuring device, 22 holding and rotating device,
24 optical position detection element, 26 laser device,
26a laser oscillator, 26b scanning mirror,
28 Arithmetic unit

Claims (6)

A dental impression material having a low laser transmittance and low shrinkage deformation is prepared, and a female model that fits into a tooth shape from a patient's tooth is manufactured using the dental impression material, and then the outer shape of the female model A tooth shape measuring method, wherein the shape is measured by a triangulation method using a laser. The tooth shape measuring method according to claim 1, wherein the dental impression material contains natural wax as a main component and contains fine particles that diffusely reflect when irradiated with laser light. The tooth shape measuring method according to claim 2, wherein the fine particles are any one of titanium oxide, calcium carbonate, barium sulfate, silica particles, or a mixture thereof. The tooth shape measuring method according to claim 2, wherein the dental impression material contains 3 wt% or more and less than 6 wt% of fine particles having an average particle diameter of 1 nm to 1 µm. An elongated model holding rod that holds the object to be measured fitted into the tooth shape at the tip, a rod holder that holds the end of the model holding rod, a model holding rod that is held horizontally, and is turned upside down A model positioning jig consisting of a support base that can be fixed to
A holding and rotating device that fixes the model positioning jig on the upper surface and rotates the object to be measured around a vertical axis that is at least close to the object to be measured, a plurality of optical position detection elements that receive reflected light from the object to be measured, A laser apparatus that is positioned between the plurality of optical position detection elements and scans the laser beam toward the object to be measured; a scanning direction of the laser light and a light receiving position of the reflected light of the laser light by the plurality of optical position detection elements A tooth shape measuring device, comprising: an arithmetic device for calculating the shape of the object to be measured. The object to be measured is composed of a dental impression material having a natural wax as a main component and low laser transmittance and less shrinkage deformation,
The tip of the model holding rod is a cylindrical shape having a slit or a surface in the axial direction, and is configured to fix the object to be measured without deforming the outer shape of the object to be measured by insertion after heating,
The rod holder has a cylindrical portion that holds the end portion of the model holding rod and a suction surface that is orthogonal to the axis of the model holding rod,
The support base has a semicircular arc inner surface that holds the cylindrical portion, and a vertical surface that faces the suction surface,
The rod holder and the support base have a concave hole for positioning on the suction surface and the vertical surface, and a positioning ball is inserted into the concave hole,
The tooth shape measuring apparatus according to claim 5, further comprising a holding mechanism that is attached to the support base and sucks the rod holder toward the support base.

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