JPWO2010024242A1 - Bioabsorbable molded article and method for producing bioabsorbable molded article - Google Patents

Abstract

The subject of this invention is suppressing the onset of the disorder | damage | failure in the replacement | exchange period from a deciduous tooth to a permanent tooth. In the present invention, the bioabsorbable molded article is composed of at least one bioabsorbable material 21 of polyglycolic acid polymer, poly-L-lactic acid polymer, or glycolic acid / lactic acid copolymer absorbed in a living tissue. , And a contrast medium 23 captured by X-ray images.

Description

  The present invention relates to a bioabsorbable molded article using a bioabsorbable material that decomposes and absorbs in a living tissue and a method for producing the bioabsorbable molded article.

  In recent dentistry, attention has been focused on medical care performed at an important time of growth and development in infant dentistry for infants. Pediatric dentistry is carried out in the dynamic transition of infant growth and development, so it cannot be understood in the same way as dentistry for adults.

  In other words, in pediatric dentistry, in addition to providing medical care such as restoration of form, function, and balance, guidance on oral function must be taken into consideration so that normal growth can be achieved.

  Therefore, in pediatric dentistry, it is necessary to provide medical care that fully considers the role of functioning of the oral cavity such as mastication, pronunciation and articulation performed during the growth and development period. For example, in articulation molding, “Ta row (Ta, Chi, Tu, Te, To), Na row (Na, Ni, Nu, Ne, No), La row (La, Li, Lu, Le, Lo)” and the like are The tongue tip is pressed against the palatal tooth jaw of the maxillary milk anterior teeth. Therefore, in dentistry for infants, treatment for pronunciation and dysarthria is one of the important purposes.

  Furthermore, in the dentistry of the deciduous dentition stage, it is necessary to take into consideration the physiological absorption of the roots of the deciduous teeth, which is observed during the exchange period between the deciduous teeth and the permanent teeth, and to promote the replacement of normal and lubricious teeth. In this way, it can be said that the significance of medical provision in pediatric dentistry extends to many limbs. In particular, when performing crown restoration with endodontic treatment on deciduous teeth, a cast high-strength metal post that is applied to adults cannot be used.

  Therefore, in current clinical settings, brass ready-made posts may be used when performing crown restoration with endodontic treatment on deciduous teeth.

  However, even with the brass ready-made post, during the physiological resorption of the roots of the deciduous teeth observed during the tooth replacement period, the restoration of the restoration due to the collision of the permanent tooth with the absorption site and the movement of the permanent tooth in the eruption direction There is a problem that causes the primary absorption failure of the deciduous tooth root.

  Therefore, in the field of pediatric dental treatment, there is a demand for a material that can be absorbed in a living tissue as an alternative to a ready-made brass post.

  As a bioabsorbable material, as a related technique 1, there is a biodegradable absorbable surgical material which is composed of only a high molecular weight polylactic acid polymer in the field of surgical medicine, melts the polymer, and further cuts the stretched composition. It is known (see, for example, Patent Document 1).

  This surgical material retains its strength for up to about 3 months when the fracture is repaired even if it is gradually decomposed as the bone regenerates from the time when the fracture or the like is fixed as an osteosynthesis material during surgical treatment. It is.

  Further, as Related Art 2, a molded body made of a crystalline thermoplastic polymer material that is biodegradable and absorbable, and the molecular chain or crystal is not uniaxially oriented and the mechanical core of the molded body There are known bone bonding materials that are oriented in parallel along a plurality of reference axes that are inclined toward an axis and a continuous surface of the axes (for example, see Patent Document 2).

  The bone cement is an indentation pressure-oriented molded body in which a polymer material is polylactic acid or a lactic acid-glycolic acid copolymer, and a part of the polylactic acid or lactic acid-glycolic acid copolymer is crystallized.

  The surgical material of Patent Document 1 or the osteosynthesis material of Patent Document 2 is intended to be decomposed and absorbed in vivo under bone and hard tissue. Moreover, the surgical material of patent document 1 or the osteosynthesis material of patent document 2 assumes decomposition | disassembly and absorption by the cell group recognized under the hard tissues including bone. Furthermore, in the surgical material of Patent Document 1 or the osteosynthesis material of Patent Literature 2, the surgical material or the osteosynthesis material is absorbed in vivo from the time when the surgical material or the osteosynthesis material is implanted into the bone.

Japanese Patent No. 2912923 Japanese Patent No. 3215046

  However, in dental treatment, the surgical material of Patent Document 1 or Patent Document 2 of Patent Document 2 is required in that it is required to be absorbed into a living body after a while (approximately 6 months to 3 years) after being embedded in milk teeth. Different from bone cement.

  Therefore, the surgical material of Patent Document 1 or the bone bonding material of Patent Document 2 is a bioabsorbable material that decomposes in vivo, which is recognized at a site where hard tissues of teeth and soft tissues where blood flow is recognized in the field of dental treatment. Has a problem that it cannot be applied as it is.

  Further, the surgical material of Patent Document 1 or the osteosynthesis material of Patent Document 2 has a problem in that it cannot grasp the process of decomposition and resorption by a cell group recognized under a hard tissue such as bone.

  Therefore, an object of the present invention is to produce a bioabsorbable composition and a bioabsorbable composition that can suppress the onset of a disorder in the replacement period from a deciduous tooth to a permanent tooth and can grasp the process of decomposition and absorption. It is to provide a method.

  According to an embodiment of the present invention, it is formed of at least one bioabsorbable material of polyglycolic acid polymer, poly-L-lactic acid polymer, or glycolic acid / lactic acid copolymer that is decomposed and absorbed in a living tissue. A bioabsorbable molded article characterized in that it contains a contrast agent shown by X-ray images.

  According to another embodiment of the present invention, at least one bioabsorbable material of a polyglycolic acid polymer, a poly-L-lactic acid polymer, or a glycolic acid / lactic acid copolymer that is decomposed and absorbed in a living tissue. In the stage before molding the molded product, a contrast agent shown by X-ray images is mixed with the bioabsorbable material or the contrast medium is molded when the molded product is molded. A method for producing a bioabsorbable molded article is obtained, wherein an agent is applied to the inner wall surface of the mold chamber of the mold and adhered to the peripheral surface of the molded article during molding.

  According to the bioabsorbable molded article and the method for producing a bioabsorbable molded article according to the embodiment of the present invention, since the molded article includes a contrast agent that is reflected by an X-ray image, it is used under a hard tissue such as a bone. The process of degradation and absorption by the recognized cell group can be grasped.

  In addition, when embedded in the deciduous teeth, after being embedded in the roots of the deciduous teeth, it continues to be maintained until the physiological absorption of the roots begins, and when the physiological absorption of the roots begins, the bioabsorbable molding Since things start to be absorbed at the same time, it becomes possible to use a timed type.

  Furthermore, when the bioabsorbable molded article partially touches the inflammatory reaction site of the tissue, it is maintained as it is, and when it is embedded in the deciduous tooth, the bioabsorbable molded article is similar to the physiological absorption of the root of the deciduous tooth. It is highly useful because it does not cause damage to the eruption of permanent teeth due to mass decomposition.

  Therefore, there is an advantage that it is possible to suppress the onset of the disorder in the replacement period from the deciduous teeth to the permanent teeth.

It is a perspective view of the post-molded article for dental root canals as an example of the bioabsorbable composition concerning one embodiment of the present invention. FIG. 2 is a side view showing a partial cross-section of an example in which the dental root canal post-molded product shown in FIG. 1 is employed in root canal treatment and crown restoration in deciduous teeth. It is the cross-sectional side view which showed the state which reached the replacement period which the milk tooth shown in FIG. 2 changed into a permanent tooth. It is explanatory drawing which shows the mixing state of the post-molded article bioabsorbable material for dental root canals and contrast agent which concerns on one Embodiment of this invention. It is a cross-sectional side view of the shaping | molding die for demonstrating the manufacturing method of the post-molded article for dental root canals shown in FIG. It is the perspective view which showed the state which rotates the shaping | molding die shown in FIG. It is sectional drawing of the shaping | molding die for demonstrating the other example of the manufacturing method of the post-molded article for dental root canals. It is a side view which shows the post molded article for dental root canals made with the shaping | molding die shown in FIG. It is explanatory drawing which shows the other example of the manufacturing method of the post-molded article for dental root canals, and shows the other manufacturing method of the bioabsorbable material and contrast agent by a shaping | molding die. It is the correlation figure which showed the correlation with the middle incisor of the upper deciduous milk tooth, and the post-molded root canal post-molded product 1. It is explanatory drawing used as the premise for demonstrating the thickness of the post-molded article for root canals. It is explanatory drawing for demonstrating the hydrolysis rate and volume change of the post-molded article for root canals. It is front sectional drawing which showed the post-molded article for root canals which modeled the middle incisor of the upper jaw side milk tooth. It is the sectional side view which showed the post-molded product for root canals which modeled the central incisor of the upper jaw side milk tooth. It is a side view which shows the post-molded product for root canal made as a prototype by PGA, and the post-molded product for root canal made by trial with PLLA.

  With reference to FIGS. 1-3, the post-molded article for dental root canals as a bioabsorbable molded article according to the first embodiment of the present invention will be described.

  A dental root canal post-molded article 1 shown in FIG. 1 includes a bioabsorbable material containing a contrast agent that is captured by an X-ray image on a molded article formed by molding a bioabsorbable material that is decomposed and absorbed in a living tissue. It is a molded product.

  Bioabsorbable materials include polyglycolic acid (hereinafter referred to as PGA) polymer, poly-L-lactic acid (hereinafter referred to as PLLA) polymer, or lactic acid / glycolic acid copolymer It is one kind of coalescence (Poly glycolic lactic acid: hereinafter referred to as PGLA).

  The bioabsorbable material is a semi-crystalline bioabsorbable polymer material. PLLA is a thermoplastic resin synthesized by direct polymerization of L-lactic acid or ring-opening polymerization of L-lactide (a cyclic duplex of lactic acid).

  The glass transition point is 35 ° C. to 40 ° C. for PGA, 55 ° C. to 60 ° C. for PLLA, and about 40 ° C. for PGLA (Glycolic: Lactic = 9: 1). The pyrolysis temperatures are 230 ° C for PGA, about 180 ° C to 178 ° C for PLLA, and 220 ° C for PGLA.

  It is known that PGA, PLLA, and PGLA have high crystallinity and a three-dimensional regular chemical structure, so that high strength is obtained and material properties are very stable.

  Bioabsorbable materials can be hydrolyzed depending on their structure, and the degradation rate is similar to other substances in terms of pH, temperature, biological activity such as enzymes, physical properties of polymers (molecular weight, strength, purity). Etc.). Since lactic acid produced by hydrolysis is a substance that can be metabolized in the living body, it has very excellent properties in terms of biocompatibility and mechanical strength.

  Further, the dental root canal post-molded product 1 shown in FIG. 1 is formed in a substantially screw shape. The dental root canal post-formed product 1 is not limited to a substantially screw shape, and may be any one of a plate shape, a pin, and a screw shape.

  The bending strength of the dental root canal post-formed product 1 is in the range of 165 MPa to 344 MPa, and the bending elastic ratio is in the range of 6 GPa to 19 GPa. In addition, the said bending strength and bending elastic ratio are the intensity | strength and bending elastic ratio required in order to embed the dental root canal post-molded article 1 in milk teeth.

  FIG. 2 shows an example in which the dental root canal post-molded article 1 is employed in root canal treatment and crown restoration in deciduous teeth. The dental root canal post-molded product 1 works effectively in order to suppress the onset of damage during the replacement period from milk teeth to permanent teeth.

  Referring also to FIG. 2, when performing crown restoration with endodontic treatment on deciduous teeth 11, root canal filling material 13 is filled into the root canal of root 12. Here, the deciduous teeth 11 are ready for eruption of permanent teeth. Furthermore, the lower root 1a of the dental root canal post-molded product 1 is embedded in the root 12. An upper part 1 b of the dental root canal post-molded product 1 embedded in the root 12 is protruded from the root 12 on the root 12. The protruding portion of the dental root canal post-molded product 1 is repaired by covering the crown restoration 14. The crown restoration 14 is out of the gum 15. Note that the tooth root 12 is held on the alveolar bone 16 below the gum 15 via the periodontal ligament 18.

  The contrast agent corresponds to the connection part of the root apex where the bioabsorbable material is absorbed and the periphery of the connection part so that the distinction between the tooth and the periodontal tissue can be seen from the X-ray image. It is concentrated and included in the post-molded article 1 for dental root canal. As the contrast agent, a positive contrast agent such as iopamidol or barium sulfate is employed.

  Specifically, a large amount of contrast agent is contained in the lower part 1a of the post-molded article 1 for a dental root canal. The contrast agent is not necessarily included in the upper part 1a of the dental root canal post-molded product 1. Further, the contrast agent may be a large amount attached to the peripheral surface of the lower portion 1a of the dental root canal post-molded product 1. The contrast agent is not necessarily attached to the upper part 1a of the dental root canal post-molded product 1.

  FIG. 3 shows a state in which an exchange period in which the milk teeth 11 shown in FIG. FIG. 3 shows a state immediately before the permanent teeth 17 push up the milk teeth 11 and the permanent teeth 17 erupt from the gums 15.

  After the dental root canal post-molded product 1 is embedded in the root 12, it is maintained as it is until physiological absorption of the root 12 of the milk tooth 11 begins. When the physiological absorption of the root 12 begins, the dental root canal post-molded product 1 also begins to be absorbed at the same time.

  That is, the deciduous tooth root of the deciduous tooth 11 is decomposed and absorbed by various cell groups in the soft tissue in the living body between the deciduous tooth 11 and the permanent tooth 17. The dental root canal post-molded article 1 is hydrolyzed by contact with body fluid in soft tissue and then absorbed by water.

  That is, the dental root canal post-molded product 1 starts to absorb the milk root, and when exposed to the outside of the tooth root, it comes into contact with the liquid in the soft tissue, and is decomposed and absorbed into the body at the same rate as the milk root. However, the decomposition and absorption of the dental root canal post-molded product 1 shows a mechanism different from the process in which the milk root is absorbed. The milk teeth 11 fall off by being pushed up in the process of the permanent teeth 17 erupting, and the permanent teeth 17 erupt onto the gums 15.

  By the way, it is known that bioabsorbable materials cause soul-like degradation during hydrolysis due to their structure. Therefore, the bioabsorbable material is partially inflamed between the deciduous teeth 11 and the permanent teeth 17 and the inflammatory reaction site (the connection portion between the root apex and the periphery of the connection portion) 31 (see FIG. 3). If touched, it is maintained as it is.

  Therefore, in a clinical setting, when the dental root canal post-molded product 1 is embedded in the tooth root 12 in the milk tooth 11, the bioabsorbable material is agglomerated similarly to the physiological absorption of the tooth root 12 of the milk tooth 11. Cause decomposition.

  Therefore, since the permanent tooth 17 is not damaged and does not hinder the growth of the permanent tooth 17, the permanent tooth 17 is not damaged. Therefore, the dental root canal post-molded product 1 is highly useful in the replacement period in which the milk teeth 11 are changed to permanent teeth 17.

  Further, when physiological absorption of the tooth root 12 starts, the dental root canal post-molded article 1 starts to be absorbed at the same time, and this process is included in the dental root canal post-molded article 1 by projecting by X-rays. It can be confirmed by contrast agent.

  FIG. 4 shows a method for manufacturing the above-mentioned dental root canal post-molded article 1. In the following description, a method of manufacturing a dental root canal post-molded product 1 that employs, as a specific example, a simple substance of PGA, a simple substance of PLLA, or a simple substance of PGLA as a bioabsorbable material will be described.

  In the method for manufacturing the dental root canal post-molded article 1, as shown in FIG. 4, a bioabsorbable material 21 of any one of PGA, PLLA, and PGLA is mixed with a contrast agent 23 captured by an X-ray image, After mixing the absorptive material 21 and the contrast agent 23, a molded product is obtained by pressure molding.

  The timing of mixing the bioabsorbable material 21 and the contrast agent 23 is either before heating the bioabsorbable material 21 or during heating. At this time, the contrast agent 23 is concentrated and mixed with the dental root canal post-molded product 1 in a concentrated manner corresponding to the connection portion of the root apex where the bioabsorbable material 21 is absorbed and the periphery of the connection portion. .

  In addition, you may mix many contrast agents 23 in the lower part 1a of the post-molded article 1 for dental root canals. Further, the contrast agent 23 is not necessarily mixed with the upper part 1a of the dental root canal post-molded product 1. Further, the contrast agent 23 may be mixed so as to decrease stepwise from the lower part 1a to the upper part 1b in a direction parallel to the axial direction of the dental root canal post-molded article 1 shown in FIG.

  A mixture obtained by mixing the bioabsorbable material 21 and the contrast agent 23 is injected into the mold chamber 41a of the mold 41 shown in FIG. 5 by the injector 43, and then the mold chamber 41a is sealed.

  Specifically, after heating at about 220 to 230 ° C. for PGA, 180 to 200 ° C. for PLLA, and 220 to 230 ° C. for PGLA, for about 60 to 90 minutes, a centrifugal casting machine (not shown) is used. Under a centrifugal force of 2000 G, the sheet is rotated for about 15 minutes as shown by an arrow A shown in FIG. Thereafter, the molded product of the dental root canal post-molded product 1 is left in a vacuum desiccator at −75 kPa for about 48 hours.

  Further, after sufficiently cooling, when the product is taken out from the mold 41, the dental root canal post-molded article 1 shown in FIG. 1 is obtained. Then, the surplus part of the dental root canal post-molded product 1 is cut, and it is further confirmed that no foreign matter is mixed.

  The dental root canal post-molded product 1 has a plate shape, a pin shape, a screw shape, or a screw shape.

  Further, as another pressure molding method, a molding die 53 using a pair of split dies 51 and 52 such as metal or silicon rubber shown in FIG. 7 is adopted. As shown in FIG. 4, after the contrast agent 23 is mixed with the bioabsorbable material 21, the bioabsorbable material 21 is injected into the mold chamber 53a of the mold 53 into the injector 55, and the mold chamber 53a is sealed. . Thereafter, when the bioabsorbable material 21 is pressure-molded by the split molds 51 and 52, a post-molded article 101 for a dental root canal is obtained.

  The bioabsorbable material 21 such as PGA, PLLA, and PGLA should have a purity and polymerization degree close to 100%, and mechanical properties change depending on the purity and polymerization degree.

  As described above, the dental root canal post-molded product 1 or 101 manufactured by containing the contrast agent 23 can easily confirm the dental root canal post-molded product 1 or 101 even in image inspection by X-ray photography. This is very significant clinically.

  The contrast agent 23 contains 10% or more of iopamidol or barium sulfate when the dental root canal post-molded product 1 or the dental root canal post-molded product 101 is 100%. Preferably, when the dental root canal post-molded article 1 or the dental root canal post-molded article 101 is 100%, iopamidol or barium sulfate is contained in an amount of 11% to 20%. The content of iopamidol or barium sulfate is not limited to the above content as long as the contrast agent is projected by X-rays. Iopamidol has been adopted for intracerebral angiography. Barium sulfate is also employed as a contrast agent for dental preparations.

  Further, the bending strength of the dental root canal post-formed product 1 or 101 is preferably in the range of 165 MPa to 344 MPa, and the bending elastic ratio is preferably set in the range of 6 GPa to 19 GPa. The bioabsorbable material 21 is decomposed and absorbed by the soft tissue of the living body. Since the post-molded article 1 or 101 for the dental root canal shows the distinction between the tooth and the periodontal tissue since the contrast agent 23 is projected by the X-ray image, it is possible to grasp the process of decomposition and absorption.

  9 employs either the mold chamber 41a of the mold 41 shown in FIG. 5 or the mold chamber 53a of the mold 53 shown in FIG. 7, and the contrast medium 23 is formed on the inner wall surface of the mold chamber 41a or the mold chamber 53. A manufacturing method is shown in which a bioabsorbable material 21 is injected into the mold chamber 41a or the mold chamber 53, and a molded product is obtained. In this case, the contrast agent 23 is disposed only on the surface of the dental root canal post-formed product 1 or 101.

  The contrast agent 23 can be attached to a desired location on the inner wall surface of the mold chamber 41a or the mold chamber 53. Specifically, the contrast agent 23 is attached in the axial direction of the dental root canal post-formed product 1,101 as a whole or in the form of dots, or stepwise in the axial direction of the dental root canal post-formed product 1,101. It can be attached or attached only to the lower part 1a. Further, the contrast agent 23 may be attached in an annular fashion in a stepwise manner in the axial direction and on the peripheral surface of the dental root canal post-formed product 1,101.

  The contrast agent 23 may not be attached to the upper part 1a of the dental root canal post-formed product 1,101.

  The dental root canal post-molded article 1,101 containing the contrast agent 23 described above can be applied as a surgical material of Patent Document 1 or an osteosynthesis material of Patent Document 2 by changing the shape of the shape.

  Hereinafter, the characteristics of the post-formed product for dental root canal will be described based on the test results.

1. Bending strength test In the bending strength test, bending strength tests were performed on PGA, PLLA, photocore, DC core paste, base cement, and brass shown in Table 1. In Table 1, Photo Core is a photopolymerization type composite for building an abutment and is a trade name of a product of Kuraray Medical Co., Ltd.

  DC core paste is a photopolymerization type abutment building composite and is a trade name of a product of Kuraray Medical Co., Ltd.

  Base cement is a base cement formed as an alternative to dentin, and is a trade name of Matsukaze Corporation.

  The results in the bending strength test were 168.3 ± 13.2 MPa for PGA and 126.7 ± 5.2 MPa for PLLA. The values exceeded the reference value of 80 MPa for the composite resin shown in ISO standard 4049 and the reference value of 50 MPa for the resin for building an abutment shown in JIS standard T 6523, respectively.

  (In addition, as shown in Table 1, in the results of the bending strength test, the photocore is 131.1 MPa, the DC core paste is 117.6 MPa, the base cement is 7.8 MPa, and the brass is 330 MPa. Is based on the bending strength described in the Japan Industrial Department Handbook and is not experimental data.)

2. Flexural modulus test In the flexural strength test, bending strength test was performed on PGA, PLLA, photocore, DC core paste, base cement, and brass shown in Table 2.

  The results of the flexural modulus test were 8.309 ± 0.60 GPa for PGA shown in Table 2 and 4.592 ± 0.28 GPa for PLLA. As a result of one-way analysis of variance, a significant difference was observed between the two. In addition, the bending elastic ratio of the root dentin is 12 to 16 GPa.

  Further, as shown in Table 2, in the results of the bending strength rate test, the photocore is 8.183 GPa, the DC core paste is 5.919 GPa, the base cement is not measurable, and the brass is 103 GPa. In addition, about brass, it quotes the bending elastic modulus as described in Japan Industrial Department handbook, and is not data by experiment.

3. Adhesion test with dental cement In the adhesion test with dental cement, the adhesive strength between base cement and PGA shown in Table 3, the adhesive strength between Fuji I and PLLA, the adhesive strength between base cement and PLLA, The bending strength ratio was tested for the adhesive strength between Fuji I and PLLA, and Fuji I and dentin.

  Fuji I is a glass ionomer cement to be worn together and is a trade name of the manufacturing company GC.

  The results of the adhesion test with the dental cement showed 1.4 ± 0.1 MPa for the base cement relative to PGA and 3.1 ± 0.0 MPa for Fuji I against PGA. The base cement showed 1.8 ± 0.1 MPa against PLLA and the Fuji I showed 3.7 ± 0.6 MPa against PLLA. Both PGA and PLLA were found to adhere to these dental cements.

  Moreover, as shown in Table 3, in the result of the adhesion test with dental cement, the adhesive force between Fuji I and dentin was 4.6 MPa.

4). Adhesive test with composite resin In the adhesive test with composite resin, the adhesive strength between G-bond (G-BOND) and PGA shown in Table 4, the adhesive strength between clear fill megabond (MEGA BOND) and PGA, The adhesion test was carried out with respect to the adhesive strength between G-bond and PLLA, the adhesive strength between base cement and PLLA, clearfill megabond and PLLA, and clearfill megabond and dentin.

  G-bond is a product that reinforces the adhesion of enamel, is a photopolymerization type one-part bonding agent, and is a trade name of a product of Yoshida Taro Co., Ltd.

  Clearfill Megabond is a photopolymerization type bonding and is a trade name of a product of Kuraray Medical Co., Ltd.

  The result of the adhesion test with a composite resin using a bonding material showed 4.4 ± 0.8 MPa for PGA with G-bond and 7.3 ± 2.9 MPa for PGA with clearfill megabond. . Moreover, 8.6 ± 1.4 MPa was exhibited for G-bond and 8.9 ± 3.6 MPa for clearfill megabond relative to PLLA.

  Therefore, when these bonding materials were used, adhesion to the composite resin was recognized for both PGA and PLLA.

  In addition, the adhesive force between Clearfill Megabond and dentin was 6.0 MPa.

  Hereinafter, the design and molding of a post-molded product for a root canal in the root canal will be described. FIG. 10 shows the correlation between the central incisor of the upper deciduous tooth and the prototype post-product 1 for root canal.

10 to 15 will be described with reference numerals in FIG. 2 used for an example in which a dental root canal post-molded product is employed in root canal treatment and crown restoration in deciduous teeth.

  Referring to FIG. 10, the size of the central incisor that is the upper deciduous tooth is 5.2 mm to 7.2 mm in the length of the crown restoration 14, and the width of the crown restoration 14 is 6.2 to 7. The length of the tooth root 12 is 7.5 mm to 11.2 mm. Therefore, the size of the root canal post-molded product 1 in the root canal 12 is set to 3.0 mm corresponding to 1/2 of the average value in the portion of the dental restoration 14. Further, the tooth root 12 portion was defined as 6.50 mm corresponding to 2/3 of the average value.

As shown in FIG. 11, the thickness of the root canal post-formed product 1 in the root canal 12 is 30 N with respect to the central portion of the 9.50 mm cylinder having the same length as the root canal post-formed product 1. The diameter to break when a horizontal force was generated was derived. In PGA, the diameter was 1.47 mm, and in PLLA, the diameter was calculated as 1.62 mm. The bending strength at this time is б = 8 Fl / πd ³ (MPa).

  Based on these results, as shown in FIG. 12, a screw-type root canal post-formed product 1 having a length of 9.50 mm and a neck (columnar) diameter of 1.62 mm was prepared.

  FIG. 13 is a front cross-sectional view showing a post-molded article 1 for a root canal using a middle incisor as a model for the upper nipple. FIG. 14 is a side sectional view showing a post-molded article 1 for a root canal using a middle incisor as a model on the upper jaw side.

  13 and 14, the lengths of the crown restoration 14 and the root canal 12 are length D = 16.1 mm. The length of the root canal post-formed product 1 is length D = 9.51 mm.

  Further, FIG. 15 shows a root canal post-molded product 1 prototyped with PGA on the upper side of the paper and a root canal post-molded product 1 prototyped with PLLA on the lower side of the paper.

  Next, the length change by hydrolysis in the post-molded article 1 for root canal immersed in the phosphate acidic buffer solution was measured.

  As shown in Table 5, in PGA, since the collapse of the exposed portion occurred 6 weeks after the start of measurement, no further measurement was possible.

  On the other hand, in PLLA, since a slow hydrolysis state was observed without causing mass collapse, measurement was continued until the 16th week.

  In the experiment, as shown in FIG. 12, 2.5 mm from the upper end of the root canal post-molded product 1 is exposed, and the rest is embedded with paraffin wax. This is referred to as long, in which 4.50 mm is exposed from the upper end of the molded product 1 and the remaining portion is embedded with paraffin wax.

  In the change in length, hydrolysis of 0.63 mm was observed for the PGA long exposed at 4.50 mm and 0.28 mm for the PLLA long exposed for 4.50 mm at the sixth week. In addition, hydrolysis of 1.06 mm was observed for the PGA short exposed at 2.50 mm, and 0.46 mm was observed for the PLLA short exposed for 2.50 mm. In both cases, the hydrolysis amount of PGA was about 1.6 times that of PLLA.

  Furthermore, in PLLA at 16 weeks, hydrolysis of 0.64 mm was observed in the PLLA long exposed at 4.50 mm, and 0.88 mm was observed in the PLLA short exposed at 2.50 mm.

  Therefore, PGA showed a faster hydrolysis rate than the deciduous tooth root, and PLLA showed hydrolysis similar to the rate of the deciduous tooth root. Thus, the property that the hydrolysis rate is close to the absorption rate of the deciduous tooth root is important.

  Furthermore, as shown in Table 6, the volume change of the root canal post-formed product 1 is shown in Table 6.

  In the volume change of the post-molded article 1 for the root canal, the PGA long exposed at 4.50 mm in the 6th week showed a volume change due to hydrolysis of 51.4%, and the PLLA long exposed at 4.50 mm was 37. A volume change was observed with 9% hydrolysis.

  Further, the PGA short exposed at 2.50 mm showed a change in volume due to hydrolysis of 76.0%, and the PLLA short exposed at 2.50 mm showed a change in volume due to hydrolysis of 43.8%.

  In the PLLA long at 16 weeks, hydrolysis was found to be 62.8% when exposed to 4.50 mm, and 64.8% when exposed to PLLA short exposed to 2.50 mm.

  In Tables 1 to 6, tests for lactic acid / glycolic acid copolymer: PGLA are not shown, but PLLA is obtained by copolymerizing glycolic acid, which is a raw material of PGA, and lactic acid, which is a raw material of PLLA. The properties differ depending on the blending ratio of glycolic acid and lactic acid.

  However, the properties of PGA do not take larger values in bending strength and flexural modulus than PGA or PLLA, and the hydrolysis rate does not become slower than PGA or PLLA.

  Therefore, PGLA having a property of an intermediate value between experimental data of PGA and PLLA can be derived.

Claims (16)

  A formed product formed of at least one bioabsorbable material of polyglycolic acid polymer, poly-L-lactic acid polymer, or glycolic acid / lactic acid copolymer that is decomposed and absorbed in a living tissue, A bioabsorbable molded article comprising a contrast agent that is captured by X-ray images.   2. The bioabsorbable molded article according to claim 1, wherein the contrast agent is a positive contrast agent.   The bioabsorbable molded article according to claim 2, wherein the positive contrast agent is iopamidol or barium sulfate.   The bioabsorbable molded article according to any one of claims 1 to 3, wherein the molded article is a post molded article for a dental root canal that is embedded in a dental root canal of a tooth. Molded product.   5. The bioabsorbable molded article according to claim 4, wherein at least a portion of the root apex where the formed material is absorbed and a periphery of the connected portion are absorbed so that a distinction between a tooth and a periodontal tissue can be understood during radiography. A bioabsorbable molded article comprising the contrast agent in a corresponding portion.   The bioabsorbable molded article according to any one of claims 1 to 5, wherein the molded article is absorbed by the soft tissue of the living body.   The bioabsorbable molded article according to any one of claims 1 to 6, wherein the molded article has a bending strength in a range of 165 MPa to 344 MPa and a bending elastic ratio in a range of 6 GPa to 19 GPa. Bioabsorbable molded product.   The bioabsorbable molded article according to any one of claims 1 to 7, wherein the molded article has a plate shape, a pin shape, a screw shape, or a screw shape. object.   A molded product is produced by molding at least one bioabsorbable material of a polyglycolic acid polymer, poly-L-lactic acid polymer, or glycolic acid / lactic acid copolymer that is decomposed and absorbed in a living tissue with a molding die. In the stage before molding the molded article, a contrast agent reflected by an X-ray image is mixed into the bioabsorbable material, or when molding the molded article, the contrast agent is applied to the inner wall surface of the mold chamber of the molding die. A method for producing a bioabsorbable molded article, which is applied and adhered to the peripheral surface of the molded article during molding.   The method for producing a bioabsorbable molded article according to claim 9, wherein the contrast agent is a positive contrast agent.   11. The method for producing a bioabsorbable molded article according to claim 10, wherein the positive contrast agent is iopamidol or barium sulfate.   The method for producing a bioabsorbable molded article according to any one of claims 9 to 11, wherein the molded article is a post molded article for a dental root canal that is embedded in a dental root canal of a tooth. A method for producing a bioabsorbable molded article.   10. The method of manufacturing a bioabsorbable molded article according to claim 9, wherein the molded article has at least the root apex of the root of which the molded article is absorbed so that a division between a tooth and a periodontal tissue can be determined by the X-ray image. A method for producing a bioabsorbable molded article comprising the contrast agent in a connection portion and a portion corresponding to the periphery of the connection portion.   The method for producing a bioabsorbable molded article according to claim 9, wherein the molded article is absorbed by the soft tissue of the living body.   15. The method for producing a bioabsorbable molded article according to claim 9, wherein the molded article has a bending strength in the range of 165 MPa to 344 MPa and a bending elastic ratio in the range of 6 GPa to 19 GPa. Method for producing a molded product.   16. The method for producing a bioabsorbable molded article according to claim 9, wherein the molded article has any one of a plate shape, a pin shape, a screw shape, and a screw shape. Manufacturing method of absorbent molded product.

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