rexresearch1
Dr. Katsu TAKAHASHI, et al
Tooth Regeneration
Tooth Regeneration
Toregem Biopharma -- USAG-1 inhibitor targets protein that inhibits tooth growth.
https://asia.nikkei.com/Business/Pharmaceuticals/World-s-first-tooth-regenerating-drug-to-enter-testing-in-Japan
World's first tooth-regenerating drug to enter testing in Japan
Startup aims to roll out antibody treatment in 2030 as alternative to implants
https://www.youtube.com/watch?v=U9PuAZbCAKQ
Scientists May Have CRACKED the Code to REGROW Missing Teeth! // Joseph R Nemeth
Toregem BioPharma.. Successful trials in mice – regrew fully functional teeth! Human clinical trials are starting soon. The treatment works through a vein injection – no surgery needed! Could replace implants and dentures in the near future!
https://jstories.media/article/the-worlds-first-drug-that-helps-patients-grow-new-teeth-update
World’s first 'teething drug' clinical trial starts in September - Aiming for full commercialization by 2030
A ray of light for patients lacking teeth, as well as the elderly
...The drug was developed by Takahashi and his colleagues, who specialized in oral surgery at Kyoto University's Graduate School of Medicine. Currently affiliated with the Medical Research Institute Kitano Hospital, Tazuke-Kofukai (Osaka City), Takahashi has been exploring the possibility of tooth regeneration for almost 30 years.
The turning point in the drug’s development came in 2018. After going through many unsuccessful experiments to increase the number of teeth with a genetically engineered virus, Takahashi and his colleagues turned their attention to a protein they called USAG-1.
Mice lacking the USAG-1 gene stop the degradation of “tooth buds,” which normally degenerate and disappear. Takahashi and his colleagues discovered this and designed an experiment to grow teeth by administering an antibody that suppresses the function of the USAG-1 protein. Ultimately, the results showed great success....
https://toregem.co.jp/
Toregem BioPharma
https://pubmed.ncbi.nlm.nih.gov/39389160/
J Oral Biosci. 2024 Dec;66(4):1-9.
doi: 10.1016/j.job.2024.10.002. Epub 2024 Oct 9.
Development of a new antibody drug to treat congenital tooth agenesis
K Takahashi, et al.
Abstract
Background: This study aimed to develop a therapeutic agent promoting teeth regeneration from autologous tissues for congenital tooth agenesis, specifically for hypodontia (≤5 missing congenital teeth, 10% prevalence) and oligodontia (≥6 missing congenital teeth, 0.1% prevalence).
Highlight: We studied mice genetically deficient in the USAG-1 protein, an antagonist of BMP/Wnt which forms excessive teeth. We identified USAG-1 as a target molecule for increasing the number of teeth. Crossing USAG-1-deficient mice with a congenital tooth agenesis model restored tooth formation. We produced anti-USAG-1 neutralizing antibodies as potential therapeutic agents for the treatment of congenital tooth agenesis. Mice anti-USAG-1 neutralizing antibodies can potentially rescue the developmentally arrested tooth germ programmed to a certain tooth type. A humanized anti-USAG-1 antibody was developed as the final candidate.
Conclusion: Targeting USAG-1 shows promise for treating missing congenital tooth. Anti-USAG-1 neutralizing antibodies have been developed and will progress towards clinical trials, which may regenerate missing congenital teeth in conditions, such as hypodontia and oligodontia. The protocol framework for a phase 1 study has been finalized, and preparation for future studies is underway.
JP2023028834
-- IMPLANT BODY AND DENTAL IMPLANT
Inventor(s): KISO HONOKA +
Applicant(s): TOREGEM BIOPHARMA CO LTD +
[ PDF ]
Inventor(s): KISO HONOKA +
Applicant(s): TOREGEM BIOPHARMA CO LTD +
[ PDF ]
To provide an implant body that can be favorably implanted above a newly growing tooth such as a permanent tooth and a regenerative tooth in an alveolar bone.SOLUTION: An implant body 130 is implanted above a newly growing tooth in an alveolar bone. The implant body 130 includes, on an upper part 131, an abutment 120 integrally formed therewith or the abutment 120 fixed thereto. At least a part of a lower part 132 of the implant body 130 is formed of a bioabsorbable material such that with the growth of the newly developing tooth, the implant body 130 becomes shorter from the tip thereof
The present invention relates to an implant body for implantation above a newly growing tooth in an alveolar bone, and to a dental implant comprising said implant body.
When a permanent tooth is lost due to dental injury or decay, this can lead to recession of the alveolar bone around the tooth or a reduction in the space between the surrounding teeth.
In the past, in order to prevent such problems, dental implants have been fixed to the alveolar bone at the site where the permanent teeth have fallen out (see, for example, Patent Document 1). Patent No. 4740139
The above-mentioned recession of the alveolar bone around a lost tooth or reduction in the space between surrounding teeth can also occur when a baby tooth is lost prematurely due to dental injury or decay rather than being naturally replaced.
However, with conventional dental implants, the titanium implant body occupies the area of the alveolar bone where the baby teeth are meant to grow, preventing the normal growth of the baby teeth. First of all, dental implants are replacements for missing teeth and are not intended to be placed in place of new teeth, such as permanent teeth.
Also, if the gap between the surrounding teeth is only reduced, a bridge denture may be able to prevent this, but the dentures will press tightly against the gums, which will still hinder the growth of baby teeth.
Furthermore, the above-mentioned problems apply not only when baby teeth are lost prematurely, but also when permanent teeth are regenerated within the alveolar cavity after they have been lost.
In view of the above, an object of the present invention is to provide an implant body and a dental implant that can be suitably embedded in the alveolar bone above a newly growing tooth, such as a permanent tooth or a regenerated tooth.
An implant body according to a first aspect of the present invention is an implant body for embedding in an alveolar bone above a newly growing tooth, characterized in that an abutment is integrally formed or fixed to an upper part of the implant body, and at least a portion of a lower part of the implant body is formed from a bioabsorbable material so as to become shorter from the tip of the implant body in accordance with the growth of the newly growing tooth.
The upper portion of the implant body may be formed from a non-bioabsorbable material.
The upper portion of the implant body may have a slower bioabsorption rate than the lower portion of the implant body.
A dental implant according to a second aspect of the present invention is a dental implant for attachment above a newly growing tooth in an alveolar bone, characterized in that it comprises a superstructure, an abutment to which the superstructure is attached, and the implant body according to the first aspect of the present invention, with which the abutment is integrally formed or to which the abutment is fixed.
According to the present invention, the implant body and the dental implant can be suitably embedded in the alveolar bone above the newly growing tooth.
FIG. 2 is a schematic cross-sectional view of periodontal tissue cut along a plane perpendicular to the dental arch, with a dental implant according to one embodiment of the present invention being attached thereto.
(a) shows the periodontal tissue immediately after the dental implant is attached, (b) shows the periodontal tissue at a later stage when the newly erupted tooth has grown in, (c) shows the periodontal tissue at an even later stage when the newly erupted tooth has grown in, and (d) shows the periodontal tissue after the newly erupted tooth has grown out of the alveolar bone and the dental implant has fallen out.
FIG. 1 is a schematic cross-sectional view of a dental implant according to one embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view of a dental implant according to a modified example of the present invention.
(Embodiment) A dental implant 100 according to an embodiment of the present invention will be described with reference to the drawings. 1(a)-(d) show schematic diagrams of periodontal tissue 200 with a dental implant 100 attached thereto. The periodontal tissue 200 of a human or other animal comprises the alveolar bone 210, which is the part of the jawbone that supports the teeth, and the gums 220 that cover the alveolar bone 210, with newly growing teeth 230 present within the alveolar bone 210. The dental implant 100 is placed in the alveolar bone 210 above the emerging tooth 230, as shown in FIG. 1(a). In this specification, "above the teeth" refers to the area above the teeth when the location within the jawbone where the teeth are currently growing is considered to be below and the direction in which the teeth will grow and protrude is considered to be above.
(Newly Erupted Tooth) The newly emerging tooth 230 may be, for example, a permanent tooth, a regenerated tooth, or a third dentition.
Permanent teeth are the teeth that come in after the baby teeth fall out. Usually, baby teeth fall out naturally as permanent teeth grow in, but sometimes baby teeth fall out prematurely due to dental injury or decay. Primary teeth may also be surgically extracted early to treat caries. The dental implant 100 is, for example, placed in the alveolar bone 210 above a permanent tooth that corresponds to such a prematurely lost or extracted baby tooth.
A regenerative tooth is a tooth regenerated from stem cells. The technique for forming the regenerated tooth is arbitrary. For example, the regenerated tooth may be formed by transplanting or inducing stem cells into the jaw, or may be formed by transplanting into the jaw a tooth organ primordium formed by the organ primordium method. The dental implant 100 is attached above the regenerated tooth within the alveolar bone 210, for example, immediately after transplantation of tissue that will become the regenerated tooth or after the regenerated tooth has formed to a certain extent within the alveolar bone 210.
The third dentition is the tooth that comes in after the permanent teeth. In mammals, there is a vestigial third dental ridge beneath the permanent teeth that has the potential to form new teeth. By locally administering an agent that promotes the growth of the third dental lamina, for example, siRNA that inhibits the expression of the USAG-1 gene, near the third dental lamina, it is possible to cause the third teeth to develop from the third dental lamina. The dental implant 100 is attached within the alveolar bone 210 above the third dental ridge, for example, immediately after administration of such agents or after the third dentition has formed to some extent.
(Configuration of Dental Implant 100) As shown in FIG. 2, the dental implant 100 includes a superstructure 110, an abutment 120, and an implant body 130.
The superstructure 110 is the part of the dental implant 100 that plays the role of a tooth. The superstructure 110 has an outer shape corresponding to the emerging tooth 230, for example, the outer shape of the superstructure 110 is the predicted shape of the emerging tooth 230 after growth is complete. The superstructure 110 can be attached to the abutment 120 , and for example, a recess into which the abutment 120 fits is provided on the lower surface of the superstructure 110 . The material constituting the superstructure 110 may be any material that is compatible with the body and has appropriate strength as a substitute for natural teeth, such as apatite-based materials (apatite, hydroxyapatite, carbonate apatite, etc.), ceramic materials, resin materials, or metal materials.
The abutment 120 is capable of attaching the superstructure 110, and is formed, for example, such that its outer shape fits into a recess in the lower surface of the superstructure 110.
The top of the abutment 120 is provided with a surface structure, such as a cross groove, that fits over the tip of a driving tool for screwing the implant body 130 into a surgically drilled hole in the jaw. The lower portion of the abutment 120 is connected to the upper portion 131 of the implant body 130 , and the abutment 120 is formed integrally with the implant body 130 . That is, the abutment 120 and the implant body 130 constitute a so-called one-piece implant. The material of the abutment 120 is the same as the material of the implant body 130, and will be described later together.
The implant body 130 is a male screw that forms a support structure that fixes the superstructure 110 to the alveolar bone 210 via the abutment 120. Most of the implant body 130 is screwed and embedded into the alveolar bone 210 . The upper portion 131 of the implant body 130 is connected to the lower portion of the abutment 120 . The lower portion 132 of the implant body 130 faces the emerging tooth 230 . The length of the implant body 130 is set so that when the implant body 130 is embedded in the alveolar bone 210 , the tip of the implant body 130 does not come into contact with the newly growing tooth 230 . For example, the length of the implant body 130 is 6 to 12 mm. Both the abutment 120 and the implant body 130 are formed from a bioabsorbable material. The bioabsorbable material may be any material that provides the abutment 120 and the implant body 130 with strength and durability suitable for a dental implant, and examples thereof include polylactic acid, polyglycolic acid, magnesium, and carbonate apatite.
The one-piece implant consisting of the abutment 120 and the implant body 130 is configured to gradually shorten from the tip of the one-piece implant in accordance with the growth of the newly growing tooth 230 by selecting the type of bioabsorbable material.
Specifically, the growth rate of the newly emerging tooth 230 within the jawbone (the rate at which the enamel-side tip of the tooth moves outward from the jawbone) can be measured by X-ray image analysis, and can also be estimated, for example, by calculating an average value based on statistical data from multiple subjects or test animals. In addition, the absorption rate (the rate at which the one-piece implant shortens) when one-piece implants of the same shape consisting of the abutment 120 and the implant body 130 are formed from different bioabsorbable materials can be determined in advance by a hydrolysis test that mimics biological conditions (for example, measuring the decomposition rate in phosphate buffered saline (pH 7.4, 37°C)). Therefore, by forming a one-piece implant from a bioabsorbable material having a resorption rate corresponding to the actual or estimated growth rate of the newly growing tooth 230 within the alveolar bone 210 (e.g., having a resorption rate equal to or greater than the growth rate, particularly having a resorption rate approximately the same as the growth rate), the one-piece implant can be made to gradually shorten from its tip as the newly growing tooth 230 grows.
For example, when the bioabsorbable material includes carbonate apatite, the bioabsorption rate can be controlled by the sintering temperature.Also, for example, when a bioabsorbable material contains a polymer, the higher the degree of polymerization and/or molecular weight of the polymer, the slower the bioabsorption rate, and the higher the content of unreacted monomer in the polymer, the faster the bioabsorption rate. Furthermore, for example, if the bioabsorbable material is composed of multiple materials with different bioabsorption rates, the bioabsorption rate of the entire bioabsorbable material can be adjusted to match the growth rate of the newly growing tooth 230 by changing the mixing ratio of these materials. Specifically, when a bioabsorbable material is composed of material A, which has a fast bioabsorption rate, and material B, which has a slow bioabsorption rate, increasing the ratio of material A to the entire bioabsorbable material will increase the bioabsorption rate of the entire bioabsorbable material, and conversely, increasing the ratio of material B to the entire bioabsorbable material will slow down the bioabsorption rate of the entire bioabsorbable material.
For example, polylactic acid is absorbed by the body more quickly than polyglycolic acid; a 4.5 mm long implant body made of polyglycolic acid will shorten to 3.9 mm in length in about 16 weeks (shortening at a rate of 37.5 μm/week) when subjected to a hydrolysis test, whereas a 4.5 mm long implant body made of polylactic acid will shorten to 3.9 mm in length in about 6 weeks (shortening at a rate of 100 μm/week) when subjected to a hydrolysis test. On the other hand, it is known that human molars grow by 20 μm per week (extending upward within the alveolar bone 210 at a rate of 20 μm/week). Therefore, when the dental implant 100 is attached above a molar tooth, the material of the abutment 120 and the implant body 130 is preferably polylactic acid. Furthermore, when a mixture of polylactic acid and polyglycolic acid is used as the bioabsorbable material, the bioabsorption rate can be adjusted to match the growth rate of the newly growing tooth 230 by changing the mixing ratio of the two.
(Surgical Method for Dental Implant 100) The dental implant 100 can be attached to the alveolar bone 210 in a one-stage procedure, similar to a typical one-piece implant. Specifically, the mucosa above the area of the alveolar bone 210 where the dental implant 100 is to be attached is incised, a hole is drilled into the alveolar bone 210, a female thread is cut into the inside of the hole, a one-piece implant consisting of the abutment 120 and the implant body 130 is screwed into the hole, and then the incised mucosa is sutured to surround the abutment 120. After the sutured mucosa has healed, the superstructure 110 is placed and fixed onto the cemented abutment 120 .
(Effects of this embodiment) If the newly growing tooth 230 is a regenerated tooth or a third tooth, during the period from when the tooth grows within the alveolar bone 210 to when it emerges from the alveolar bone 210, there is a risk that the alveolar bone 210 around the tooth will shrink or the space between the surrounding teeth will become smaller. This problem can also occur if baby teeth are lost prematurely due to dental injury or decay. The recession of the alveolar bone 210 inhibits the growth of the newly erupted teeth 230 . Additionally, a reduction in the interdental spacing may prevent the emerging teeth 230 from erupting along the dentition between the existing teeth, which may result in the emerging teeth 230 erupting to the side out of the dentition.
Additionally, while a conventional dental implant may be placed within the alveolar bone 210 above the newly emerging tooth 230 to prevent the alveolar bone 210 from shrinking around the site of placement and to prevent a reduction in the spacing between the surrounding teeth, the dental implant body itself inhibits the growth of the newly emerging tooth 230.
Even if the newly growing tooth 230 were able to grow, the newly growing tooth 230 would grow out from the side of the alveolar bone 210 in a way that would avoid the dental implant. Firstly, conventional dental implants are not intended to be placed in the location where a new tooth, such as a permanent tooth, is to be formed.
On the other hand, according to the dental implant 100 of this embodiment, by attaching it above the newly growing tooth 230 within the alveolar bone 210, it is possible to prevent recession of the alveolar bone 210 around the attachment location and reduction in the space between the teeth around the superstructure 110 of the dental implant 100. In addition, as shown in FIGS. 1(a) to (d), the one-piece implant (particularly the portion of the implant body 130) consisting of the abutment 120 of the dental implant 100 and the implant body 130 gradually becomes shorter from its tip in accordance with the growth of the newly growing tooth 230, so that the growth of the newly growing tooth 230 is not hindered, but rather the scar of the absorbed implant becomes a path for the newly growing tooth 230 to grow, which helps the newly growing tooth 230 to grow neatly in line with the dentition. By the time the newly growing tooth 230 emerges from the alveolar bone 210, most of the one-piece implant (especially the implant body 130) has been decomposed and absorbed and is no longer there, so the dental implant 100 will eventually fall out just like a baby tooth naturally falls out.
(Modifications) Various modifications of the above-described embodiment will be described below. The above-described embodiment and the following modified examples can be freely combined with each other unless there is a contradiction.
(Modification 1) In the above-described embodiment, the abutment 120 and the implant body 130 are formed from the same material. Alternatively, however, the two may be formed from different materials. In particular, the abutment 120 may be formed from a non-bioabsorbable material. When the abutment 120 and the implant body 130 are formed from different materials, the abutment 120 and the implant body 130 may be formed integrally or may be formed as separate pieces and then fixed to each other. Since the abutment 120 is fixed to the alveolar bone 210 via the implant body 130, when most of the implant body 130 is lost due to the growth of the newly growing tooth 230, the abutment 120 will come out of the alveolar bone 210 regardless of the material of the abutment 120. Of course, once removed, the abutment 120 will not adversely affect the growth of the newly growing tooth 230.
(Variation 2) In the above-described embodiment, the bioabsorption rate of the bioabsorbable material forming the implant body 130 is equal to or greater than the growth rate of the newly growing tooth 230 in the alveolar bone 210. Alternatively, the bioabsorption rate of the bioabsorbable material forming the implant body 130 may be slower than the growth rate of the newly growing tooth 230 in the alveolar bone 210. Generally, even before a bioabsorbable material is completely decomposed and absorbed, it becomes embrittled due to partial decomposition and absorption. For this reason, the implant body 130 is easily broken through by the newly growing tooth 230, so there is no problem even if the bioabsorption rate of the bioabsorbable material forming the implant body 130 is slower than the growth rate of the newly growing tooth 230 within the alveolar bone 210. In other words, the bioabsorption rate of the bioabsorbable material forming the implant body 130 is sufficient so long as the impact site is sufficiently embrittled by the time the newly growing tooth 230 impacts the implant body 130.
(Variation 2-1) In this case, as shown in FIG. 3, it is preferable that a cavity be provided inside the implant body 130 (particularly inside the lower portion 132 of the implant body 130) so as to accommodate the portion of the implant body 130 that has been broken through. This configuration reduces the pressure that the newly growing tooth 230 receives from the remains of the implant body 130 that has broken through and collapsed after breaking through the implant body 130.
(Variation 2-2) Furthermore, when carbonate apatite is used as the bioabsorbable material, the carbonate apatite is easily absorbed by odontoclasts and/or osteoclasts that increase in the surrounding area as the new tooth grows, and does not adversely affect the growth of the newly growing tooth 230. In this case, the bioabsorption rate of the bioabsorbable material forming the implant body 130 may be slower than the growth rate of the newly growing tooth 230 within the alveolar bone 210 . This is also true for other bioabsorbable materials that can be readily absorbed by odontoclasts and/or osteoclasts. Conversely, even if the bioabsorbable material is ultimately absorbed by odontoclasts and/or osteoclasts, if the absorption rate is slow and may adversely affect the growth of the newly growing tooth 230, the bioabsorption rate of the bioabsorbable material forming the implant body 130 should be equal to or greater than the growth rate of the newly growing tooth 230 within the alveolar bone 210.
(Variation 3) In the above-described embodiment, the abutment 120 is formed integrally with the implant body 130. Alternatively, the abutment 120 and the implant body 130 may be formed as independent parts and fixed to each other.
The abutment 120 and implant body 130 may be formed as separate pieces and permanently secured together by any means, such as a biocompatible adhesive.
Alternatively, the abutment 120 and the implant body 130 may be formed as independent components and detachably fixed to each other. That is, the dental implant 100 may be a so-called two-piece implant. The means for removably fixing the abutment 120 and the implant body 130 to each other is arbitrary. For example, the abutment 120 and the implant body 130 may be fixed to each other by a male thread provided on the lower surface of the abutment 120 and a female thread provided on the upper portion 131 of the implant body 130 . Alternatively, a through hole may be provided in the center of the abutment 120, a female thread may be provided on the upper portion 131 of the implant body 130, and an abutment screw, the screw head of which does not pass through the aforementioned through hole but has a male thread at least at its tip that fits the aforementioned female thread, may be screwed through the through hole into the female thread, thereby fixing the abutment 120 and the implant body 130 to each other.
The fixing means for removably fixing the abutment 120 and the implant body 130 to each other, such as a male screw or an abutment screw provided on the underside of the abutment 120, may be formed from a bioabsorbable material or a non-bioabsorbable material.
(Variation 4) In the above-described embodiment, the entire implant body 130 is formed from the same material. Alternatively, the upper portion 131 and the lower portion 132 of the implant body 130 may be formed from different materials. In this case, the upper and lower portions 131, 132 of the implant body 130 may be formed as a single unit, or may be formed as separate pieces and then permanently fixed to each other by any means, such as a biocompatible adhesive.
The lower portion 132 of the implant body 130 is formed from a bioabsorbable material. On the other hand, the upper portion 131 of the implant body 130 may be formed from a bioabsorbable material or a non-bioabsorbable material. In this case, the bioabsorbable material forming the lower portion 132 may have a faster bioabsorption rate than the growth rate of the emerging tooth 230 within the alveolar bone 210 .
(Modification 4-1) When the upper portion 131 of the implant body 130 is made of a bioabsorbable material, it is preferable that the bioabsorption rate of the upper portion 131 of the implant body 130 is slower than the bioabsorption rate of the lower portion 132 of the implant body 130. According to this, the upper part 131 of the implant body 130 is maintained for a longer period of time than the lower part 132 of the implant body 130, so that the dental implant 100 remains firmly fixed to the alveolar bone 210 until the final stage of growth of the newly growing tooth 230, and does not fall out midway.
For example, the upper portion 131 of the implant body 130 may be formed from one bioabsorbable material, and the lower portion 132 of the implant body 130 may be formed from another bioabsorbable material that is absorbed faster than the upper portion 131 of the implant body 130 .
In addition, for example, the implant body 130 may be composed of multiple portions formed from multiple types of bioabsorbable materials, or may be composed of a gradation composition of multiple types of bioabsorbable materials, so that the bioabsorption rate of the implant body 130 slows from the bottom to the top of the implant body 130. Even in this case, the bioabsorption rate of the entire upper portion 131 of the implant body 130 can be considered to be slower than the bioabsorption rate of the entire lower portion 132 of the implant body 130 . The gradation composition can be realized by mixing bioabsorbable materials A and B to form implant body 130 based on a mixing ratio such that the abundance ratio of bioabsorbable material A decreases from bottom to top and conversely, the abundance ratio of bioabsorbable material B increases, for example, assuming that the bioabsorption rate of bioabsorbable material A is faster than the bioabsorption rate of bioabsorbable material B, and that at the lower end (tip) of implant body 130, the proportion of bioabsorbable material A is 100% and the proportion of bioabsorbable material B is 0%, at the center, the proportion of bioabsorbable material A is 50% and the proportion of bioabsorbable material B is 50%, and at the upper end of implant body 130, the proportion of bioabsorbable material A is 0% and the proportion of bioabsorbable material B is 100%.
(Variation 4-2) When the upper portion 131 of the implant body 130 is formed from a non-bioabsorbable material, the dental implant 100 remains firmly fixed to the alveolar bone 210 until the end of the growth of the newly growing tooth 230, and does not fall out midway. In addition, just before the baby teeth grow in, the newly growing teeth 230 will hit the upper part 131 of the implant body 130 made of a non-bioabsorbable material, causing the entire dental implant 100 to become loose. This allows the patient to know when to visit a dentist to surgically extract the dental implant 100 or to determine whether it should be extracted (e.g., to determine whether the mobility is due to normal development of the emerging tooth 230 or is due to disease such as periodontal disease). Therefore, there is no problem even if the upper portion 131 of the implant body 130 made of a non-bioabsorbable material does not come off spontaneously. In addition, if the newly growing tooth 230 does not grow in due to developmental deficiencies unrelated to the dental implant 100, the dental implant 100, in which the upper portion 131 of the implant body 130 is formed from a non-bioabsorbable material, remains firmly fixed to the patient's alveolar bone 210 and functions in the same manner as a normal dental implant.
If the upper portion 131 of the implant body 130 is formed from a non-bioabsorbable material, the length of the upper portion 131 may be short. If the length of the upper part 131 of the implant body 130 is short, the fixing force to the alveolar bone 210 will be weakened, so that when the newly growing tooth 230 hits the upper part 131 of the implant body 130, the upper part 131 of the implant body 130 will tend to come off naturally. Furthermore, as the newly growing tooth 230 grows, the alveolar bone tissue directly above the tooth is decomposed and absorbed, as shown in Figures 1(c) and (d). Therefore, if the upper part 131 of the implant body 130 is sufficiently short, when the newly growing tooth 230 hits the upper part 131 of the implant body 130, the alveolar bone tissue around the upper part 131 of the implant body 130 is decomposed and absorbed, the bond between the upper part 131 of the implant body 130 and the alveolar bone 210 loosens, and the implant body 130 comes out naturally. For example, the length of the upper portion 131 of the implant body 130 may be 2 to 3 mm.
As in the above-described modified example, the lower portion 132 may be composed of multiple portions formed from multiple types of bioabsorbable materials, or may be composed of a gradation composition of multiple types of bioabsorbable materials, so that the bioabsorption rate of the lower portion 132 slows from the bottom to the top of the lower portion 131 of the implant body 130.
(Variation 5) In the above-described embodiment, the dental implant 100 is a one-piece implant, but the structure of the dental implant 100 can be configured similarly to any conventional dental implant, except that at least a portion of the lower portion 132 of the implant body 130 is formed from a bioabsorbable material so that it shortens from the tip of the implant body 130 in accordance with the growth of the newly growing tooth 230. In this case, the dental implant 100 can be surgically attached above the emerging tooth 230 within the alveolar bone 210 of a human or other animal, depending on the anatomy of the dental implant.
100 Dental implant 110 Superstructure 120 Abutment 130 Implant body 131 Upper part of implant body 132 Lower part of implant body 200 Periodontal tissue 210 Alveolar bone 220 Gums 230 Newly growing tooth