JP2013146469A - Surface properties of fixture for dental implant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide surface properties of a fixture for strengthening the fixing with an alveolar bone, and stably and safely retaining an implant in the long term, in a fixture of an osseointegrated implant.SOLUTION: In a dental implant, a fixture 18 to be implanted in an alveolar bone has areas with different surface properties. As for the surface property, the fixture has the different surface-property areas separated into the side of an apical portion 24 and the side of a neck portion 26. An integrated state thereof with the alveolar bone for accelerating osseointegration is different depending on the surface property. The side of the neck portion 26 of the fixture is of titanium or titanium alloy having fine irregularities formed thereon. The side of the apical portion 24 is of hydroxyapatite. The surface of the neck portion side may be treated with alkali.

Description

The present invention relates to an artificial dental implant for prosthesis of a lost tooth, and relates to a fixture surface property adapted to pressurization by a chewing function of a tooth.

  In order to regain the function of teeth lost due to dental caries and periodontal disease, as a means of supplementing oral functions lost by replacing with artificial materials such as metal and ceramics, dentures are buried in the root or completely lost to the root In such cases, there are treatment methods such as placing a denture with a bridge on healthy teeth. Furthermore, oral implant treatment is currently being implemented as one of the advanced treatments for this dental replacement medicine. Oral implant treatment is a means of implanting a titanium artificial tooth root in the jawbone at the site of the lost tooth.

  When implanting artificial roots in the jawbone of the lost tooth site, i.e., the alveolar bone, with normal artificial materials such as metal, the connective tissue of the alveolar bone surrounds and eliminates the artificial material, so the sway gradually increases and becomes artificial. The function as a tooth root was lost.

  In 1952, Sweden's Per Ingvar Brönemark accidentally discovered that titanium and bone were completely combined, and when titanium was implanted in the bone under certain conditions, bone rejection to titanium Did not occur at all, and it was revealed that a strong bond was born through the oxygen film covering the titanium surface. In 1965, the first clinical application as an artificial tooth root was started. Since then, oral implant treatment has made tremendous progress. The bone connection method, in which titanium and bone are directly connected without intervening connective tissue, is called osseointegration, which is a combination of Latin male (os) for bone and English integration for bone. It is.

  Osseointegration is a phenomenon in which bone and metal are directly bonded, and the force acting on the contact surface between the oxide film on the titanium surface and the bone bonds biological molecules to the oxide film to cause bone adhesion. Therefore, the success of implants is important in how to obtain osseointegration.

  Bone and teeth, which are inorganic substances, are mainly composed of hydroxyabatite. In order to promote the growth of osseointegration, a method of coating the surface of the fixture with hydroxyabatite has been proposed (for example, Patent Document 1). reference).

  When the implant is implanted in the body, the detection activity is started in the living body by macrophages and foreign substance detection cells in the living body in the living body against the foreign body's implantation, but it constitutes hydroxyapatite or the base of the implant It is said that when hydroxyapatite is coated on the surface of the metal material to be detected, these are close to the tissue composition of the bone, so the foreign substance detection cell is determined as a living tissue, and the cell-bone connection proceeds early. .

  As a consideration from the viewpoint of the mechanical stability of the fixture embedded in the alveolar bone, a shape device is also devised. In this case, excessive pressure results in bone resorption, but is based on Wolff's law, which says, “The bone strength is changed by remodeling the bone according to the mechanical demand of the bone.” There are several examples of geometrical considerations on how to avoid excessive pressure and how to disperse structurally to moderate pressure.

  If the root part of the fixture is basically cylindrical, this shape will not achieve the desired main stability after surgery of the fitted implant and will loosen in years. Come. This is because an excessive force is applied to the bone-bonded portion, resulting in bone resorption. For this reason, it is assumed that the straight cylindrical shape is not the most suitable shape. A shape having an outer contour (outer shape) has been proposed (see, for example, Patent Document 2).

  In addition, the masticatory function is proposed with a shape in which the bottom surface of the implant is horizontal, assuming that the maximum load is applied vertically to the implant (see, for example, Patent Document 3).

  Natural teeth have periodontal ligaments that are connected to the jawbone by band-bonded planting, and have a minute mobility function corresponding to mastication. Teeth with bone adhesion do not have this micro-mobility function and are always damaged by repeated pressurization. Therefore, artificial teeth with a shape that creates a fibrous tissue such as the original periodontal ligament after the artificial root is set up Proposals for tooth roots have also been attempted. The proposed artificial tooth root is a cylindrical shape having a crown at one end and a root apex at the opposite end, and bulges and depressions are alternately formed on the side surface along the axial direction. It is a feature (see, for example, Patent Document 4).

  In addition, the artificial tooth root has a double structure of an outer cylinder and an inner tooth root, and the outer cylinder and the inner tooth root are fixed with a resin adhesive, and the function of the original periodontal ligament is substituted with the resin adhesive as a cushioning material. There is also a proposal (see, for example, Patent Document 5).

In this way, various efforts have been made for implants in the past, but with regard to the connectivity between the fixture and the alveolar bone, the focus is on how tightly they are connected using osseointegration. This is the current situation.

Japanese Patent Laid-Open No. 2006-314760 Special table 2003-513684 literature Japanese Patent Laid-Open No. 2006-269558 Japanese Patent Laid-Open No. 6-154246 Japanese Patent Laid-Open No. 7-213540

  Osseointegrated implants based on osseointegration are prosthetic treatments that restore oral function resulting from dental defects. It is a system in which an implant is placed in the alveolar bone and directly connected to the bone, and the establishment and maintenance of osseointegration is essential for long-term success. For the establishment of this osseointegration, the factors resulting from the implant material, shape, and surface texture, as well as the bone state and load state, are important factors.

  The load state is considered to be the most important factor for maintaining the established osseointegration for a long time. This is because if the load state is inappropriate and there is a portion where the load is excessively concentrated on the alveolar bone around the implant, bone resorption occurs due to bone micro-damage and osseointegration is lost.

  Teeth that are based on Wolff's law, which says, “We will remodel bones according to the degree of mechanical demand for bones and change their strength.” Because of the function of chewing food, it is not possible to control the load, and when implanting, due to its physical and shape effect, the shape that disperses without concentrating the load can be formed It has been considered at the center.

  The surface properties of fixtures have also been considered from the viewpoint of efficient osseointegration in order to firmly bond with the alveolar bone.

  For this reason, there has been almost no report on how the surface texture of the fixture should be related to the long-term stability or safety of the implant.

The present invention relates to a fixture of an osseointegrated implant, and aims to provide a fixture surface property for maintaining the implant stably and safely for a long period of time while firmly fixing to the alveolar bone. It is said.

  The present invention is characterized in that, in a dental implant, a fixture embedded in an alveolar bone includes regions having different surface properties. The surface texture of the fixture has different surface texture regions separated on the apical and cervical sides, and the bonding state with the alveolar bone that promotes osseointegration depends on the surface texture. And

  The neck side of the fixture is titanium or a titanium alloy having fine irregularities on the surface, and the apex side is hydroxyapatite. The neck side surface may be treated with alkali.

  Moreover, the neck side of the fixture is titanium or a titanium alloy having fine irregularities on the surface, and the surface on the apex side may be subjected to alkali treatment.

The dental implant fixture according to the present invention can be manufactured by manufacturing the entire fixture as titanium or a titanium alloy having fine irregularities on the surface and coating the apical side with hydroxyapatite, or by alkali treatment. It is. When hydroxyapatite is coated on the apical portion side, it may be peeled off due to friction with bone. Therefore, the apex portion on the apical portion side may be prevented from being coated with hydroxyapatite.

  The dental implant fixture according to the present invention provides sufficient initial fixation, disperses the load due to occlusion, prevents bone resorption, promotes osseointegration, and provides a stable implant over a long period of time. Has the effect of

Moreover, since the entire fixture can be manufactured as titanium or titanium alloy having fine irregularities on the surface and coated with hydroxyapatite on the apex side, it is possible to use dental implants that are commercially available in the past. Can be realized easily.

The figure which shows the fixture surface property of the implant by this invention. The figure which shows the fixture surface property of the other implant by this invention Sectional drawing for demonstrating the structure of a tooth | gear. The figure explaining the state which implanted the implant. The figure which shows the analysis model for finite elements. The figure explaining the constraint conditions in the case of calculating a finite element method. The figure explaining the load conditions in the case of calculating a finite element method. The figure which shows the Mises stress analysis result to the alveolar bone by a finite element method. The figure which took out the part from which Mises stress to an alveolar bone becomes 10 GPa or more as a bone resorption site. The figure which shows the change of the frequency | count of analysis, and a bone resorption site | part. The figure which shows the frequency | count of an analysis at the time of applying Wolff's law, and the change of a bone resorption site | part. The model figure explaining the combined state of an alveolar bone and a fixture.

  Although the implant is used as a substitute tooth, an occlusal force is applied to the fixture from the upper heel structure via the abutment by the occlusal action by mastication. Since the fixture is embedded in the alveolar bone, the load applied to the upper jaw structure is transmitted from the fixture to the alveolar bone, and stress is generated in the alveolar bone. When this stress is an appropriate value, the alveolar bone is regenerated and strengthened according to Wolff's law, but when an excessive occlusal force is applied, it causes bone destruction and resorption, and eventually fails.

  For this reason, in the present invention, the fixture shape from a macroscopic viewpoint that has been studied conventionally has been made by focusing on the surface properties effective in preventing alveolar bone collapse from a microscopic viewpoint. .

  FIG. 1 shows the surface properties of a fixture according to the present invention. In FIG. 1, the fixture unit 10 shows a color unit 20 and a fixture 18, and no osseointegration is developed in the color unit 20. The fixture 18 is provided with a guide protrusion 22 that assists in embedding. The alveolar bone is implanted from the apex 24 to the neck 26. The fixture shape in FIG. 1 is an example, and any other fixture shape may be used.

  The surface properties of the fixture part 10 include a polishing part 12 where osseointegration does not occur, a metal surface part 14 where osseointegration partially appears, and osseointegration due to the function of osseointegration with the alveolar bone. Is composed of an HA portion 16 that is expressed in substantially the entire region. The metal surface part 14 is titanium or a titanium alloy, and the surface is in a minute uneven state. The HA portion 16 is hydroxyapatite, and the hydroxyapatite can be coated on a titanium or titanium alloy fixture by coating.

  FIG. 2 shows the surface property of the fixture according to the present invention described in FIG. 1, and the tip of the apex portion has a surface property that is not coated with a coating, and the metal surface includes the metal surface portion 14-1 and the metal surface portion. 14-2 are provided. Hydroxyapatite coating is performed by thin film coating using plasma spraying or semiconductor technology, but the tip of the apex has a particularly high frictional force with the bone when the implant is placed, and the coating film peels off due to this frictional resistance. This is also possible. Even in this case, the effect of the present invention can be obtained.

  Thus, the fixture surface property according to the present invention is characterized by having a region where osseointegration is partially expressed and a region where osseointegration is expressed in substantially the entire region.

  Hereinafter, the reason why the fixture surface property of the present invention is effective for implant treatment will be described.

  FIG. 3 is a cross section showing the tooth structure 30. In FIG. 3, the tooth itself is divided into a crown that is a surface portion and a tooth root that is a portion hidden in the gums, and the structure is enamel 32, dentin 36, pulp 38 and cement. It consists of quality 34. The gums are composed of gingiva 40, attached gingiva 42, alveolar bone 44 and periodontal ligament 46.

  The outermost part of the tooth is enamel 32, and the surface part of the crown is almost enamel. Enamel is made of hard calcium phosphate. The enamel has a thickness of about 2 to 3 mm and has a structure that is harder toward the tooth surface and softer toward the inside. The cementum 34 is inside the tooth enamel 32. The cementum 34 is inside the enamel 32 where the teeth protrude from the surface and the outermost part where the teeth are in the gums. It also serves to protect the dentin 36 inside the cementum 34. The dental pulp 38 is in communication with blood vessels and nerves, and is connected to blood vessels and nerves with a root canal 48.

  Teeth are fixed in the mouth by gums, and there are alveolar bones 44 around the periodontium, which are also called alveolar processes, and play the role of a mouth for fitting the teeth into the skull. The periodontal ligament 46 connects the teeth and the alveolar bone 44 and includes nerves and capillaries. The gingiva 40 and the attached gingiva 42 are tissues that protect the portion connecting the tooth and the alveolar bone 44, and protect the periodontal membrane 48 through which nerves and blood vessels pass.

  FIG. 4 is a diagram showing a state in which an implant is implanted. The implant 50 includes a crown 52 serving as a tooth profile, a fixture 18 embedded in the alveolar bone 44, and an abutment 54 that couples the crown 52 and the fixture 18. The abutment 54 is generally structured to be screwed into the fixture 18, and the crown 52 is bonded to the abutment 54 with an adhesive.

  The implant 50 is screwed into a cavity opened in the alveolar bone 44 using a guide protrusion, and is implanted in a state where the fixture 18 and the alveolar bone 44 are in contact with each other. The implant surface is titanium or a titanium alloy that can be combined with a living body due to the appearance of osseointegration, and fine irregularities are formed on the surface in order to promote osseointegration. Recently, hydroxyapatite has also been used. In hydroxyapatite, osseointegration is developed over the entire surface area, and it is possible to fix the implant more firmly.

  As apparent from the implantation state of the implant 50 shown in FIG. 4, the actual tooth structure shown in FIG. 3 is different from the fact that there is no pulp 38 and no periodontal membrane 46. . The periodontal ligament 46 is a fibrous connective tissue also called periodontal ligament. It is interposed between the alveolar bone 44 and the cementum 34 to fix the teeth in the jawbone and is representative of occlusal and external forces without calcification. It also plays a role in buffering so that mechanical stress is not directly applied to the jawbone.

  In addition to the fiber and cell components typified by collagen fibers, there are also blood vessels and nerves, which serve as a sensory device that senses various external stimuli (pain and pressure sense), periodontal tissue homeostasis. Although it also plays a role of maintenance, most people feel that it is completely different from natural teeth in terms of the feeling of the person who actually uses the implant, and now the periodontal ligament 44 is attached to the implant 50. There is less to be regarded as a problem.

  For this reason, mechanical stress, which is an occlusal force transmitted from the upper collar structure to the fixture via the abutment due to the occlusal action by mastication, is regarded as a main issue.

  Next, we analyze the stress applied to the alveolar bone from the implant placed against the mechanical stress by the finite element method and consider the failure of the alveolar bone.

  FIG. 5 shows an analysis model 60 by the finite element method for performing stress analysis on the alveolar bone 44 by the implant 50. Here, the purpose is to clarify the relationship between the shape of the fixture that is the portion of the implant embedded in the alveolar bone 44 and the stress, and the implant model is obtained by adding an abutment to the fixture. The fixture and alveolar bone were assumed to be completely joined. In FIG. 1, the mesh in the alveolar bone 44 is a mesh with finer element division than other parts in order to analyze the stress in the vicinity of the implant in detail. The X axis, Y axis, and Z axis are shown in FIG.

  The analysis model 60 targets 1/2 cut from the center in order to shorten the calculation time of analysis. Furthermore, in order to facilitate the analysis, the fixture shape was modeled as a cylindrical shape with a semicircular shape at the apex.

  FIG. 6 shows constraint conditions for performing analysis by the finite element method. The constraint condition is that the distal surface of the alveolar bone 44 is the total constraint and the mesial surface is the target constraint.

  FIG. 7 shows load conditions for performing analysis by the finite element method. The load conditions were a total load of 100 N vertically below 45 degrees and an evenly distributed load on the upper surface of the abutment. Thereby, the load component in the horizontal direction and the vertical direction becomes 70.9N.

  The physical properties of the implant 50 were set to 116 as a Young's modulus E and 0.3 as a Poisson's ratio as titanium which is a fixture material. The physical property value of the alveolar bone 44 was determined by setting the Young's modulus E to 0.203 and the Poisson's ratio to 0.4 based on the bone quality classification D3 of Mish.

  FIG. 8 shows the result of analysis under the above conditions by the finite element method and shows the Mises stress on the alveolar bone. Mainly around the periphery of the fixture neck and around the apex, the maximum was 14.22 GPa, and the minimum was 0.073 GPa of the alveolar bone bottom.

  Alveolar bone collapse, i.e., bone resorption, does not occur within a physiologically acceptable range, but it is recognized that bone resorption occurs when the physiologically acceptable range is exceeded. Although there is no generally accepted value for the physiologically acceptable range of the alveolar bone, it is considered that a reasonable value of about 10 GPa is practically reasonable based on clinical experience.

  Therefore, as shown in FIG. 9, the site where the Mises stress 66 on the alveolar bone exceeded 10 GPa was designated as the bone resorption site 68 where bone resorption occurred, and this element portion was removed, and the analysis was repeated. In the actual analysis, an element whose Mises stress exceeds 10 GPa is extracted from the first analysis result, and the Young's modulus E of the extracted alveolar bone element is changed from 0.203 to 0.00001 without changing other conditions. A second analysis was performed and repeated analysis was performed in the same manner.

  FIG. 10 shows the results of repeated analysis. In FIG. 10, the number of bone resorption elements whose Mises stress exceeds 10 GPa is displayed according to the number of analyses. Bone resorption elements with Mises stress exceeding 10 GPa, the number of analyzes increases as the number of analysis increases around the periphery of the neck of the fixture and the periphery of the apex, and at the seventh time, the bone resorption site is completely connected, The result was that it would fail.

  In reality, the phenomenon that the implanted implants fail 100% has never happened, and Wolff says, “We will change the strength by remodeling the bone according to the mechanical demand of the bone.” It is considered necessary to apply the law. In the case of applying Wolff's law, analytically, the element in which the Mises stress exceeded 10 GPa in the alveolar bone 44 was first extracted from the first analysis result as in the above-described analysis method. The Young's modulus E of the physical property values of these extracted elements was changed from 0.203 to 0.0203, which was weakened to 10%, and the second analysis was performed without changing other conditions.

  Furthermore, from the analysis result of the second time, the Young's modulus E of the element whose Mises stress exceeds 10 GPa is changed from 0.203 to 0.0406 which is weakened to 20%, and the third analysis without changing other conditions. Went. In the third analysis, the Young's modulus E of the element whose Mises stress exceeds 10 GPa is set to 0.0609 which is a value weakened from 0.203 to 30%, and the fourth analysis is performed without changing other conditions. The analysis was performed up to the eighth time in the same manner.

  FIG. 11 is an analysis result showing the number of times of analysis and the bone resorption site 72 when Wolff's law is applied. The Young's modulus E used for the number of analyzes is also shown. From this analysis result, the bone resorption part that occurred in the peripheral edge part of the neck of the fixture and the peripheral edge part of the apex part decreases as the analysis operation is repeated, and the bone resorption part becomes zero by the eighth operation, The bone resorbed part converged and stabilized without the implant failing. The stress concentration around the alveolar bone gradually moved deeper and dispersed.

  From this result, if the physical properties of the alveolar bone are uniform, the stress of the alveolar bone with respect to the load will always be concentrated around the peripheral edge and apex that contact the neck of the fixture, avoiding this stress Therefore, the living body undergoes an adaptive reaction that weakens the bone quality at the stress concentration site. As a result, the portion in contact with the fixture is made weaker than the original physical property value of the alveolar bone, and is dispersed in the peripheral portion while avoiding stress concentration.

  As described above, we considered that the failure of the implant could be prevented by the stress concentration and the weakening of the alveolar bone from a macro viewpoint under the condition that the fixture of the implant and the alveolar bone were completely combined. From the viewpoint of surface properties. The surface texture is when osseointegration is incomplete and a partial gap exists between the fixture and the alveolar bone.

  FIG. 12 is a diagram modeling the connection relationship between the fixture and the alveolar bone from a microscopic viewpoint in order to consider the relationship with the surface texture. FIG. 12A shows a complete connection model when the fixture 18 and the alveolar bone 44 are completely connected, and FIG. 12B shows a state where the fixture 18 and the alveolar bone 44 are partially incomplete. This is a partial coupling model when coupled.

  The load is applied to the alveolar bone 44 via the fixture 18. In the case of a fully coupled model, a load is applied to the lower side of FIG. 12 with respect to the occlusal force at the fixture 18, and a force acts in the opposite direction as stress at the alveolar bone 44. The load is in a completely coupled state between the fixture 18 and the alveolar bone 44, and is applied to the entire surface of the alveolar bone 44, and stress is also generated in the entire alveolar bone 44. A lateral load from the fixture 18 is also applied to the entire surface of the alveolar bone 44, and a force acts on the alveolar bone 44 in the opposite direction as stress.

  On the other hand, in the partially coupled model, the downward load in FIG. 12 is only the region that is partially coupled. The load in the right direction of the fixture 18 in FIG. 11 is applied to the joint portion, and at the same time, the alveolar bone 44 is not completely solid, so a part of the load is applied to the gap portion where the joint portion is pushed and not joined. This is considered to be the case. A load in the left direction from the fixture 18 is applied to the joint portion, but since the gap portion is not joined, no stress acts.

  In such a state where stress is generated, stress is concentrated at the joint portion. However, the displacement of the fixture increases due to the gap existing in the portion that is not joined, but the macroscopic stress is considered to be dispersed. If the analysis result when applying the above-mentioned Wolff's law is applied to this partial coupling model, stress concentrates on the coupled part and the alveolar bone becomes weak, and the load from the fixture It is considered that the failure of the implant can be prevented by fulfilling the function of substituting the alveolar membrane for converting the stress into dispersed stress.

  However, when the entire fixture is in the state of a partial bond model, even if it functions as a substitute for the alveolar membrane, the bonding force is weak, and the fixation between the fixture and the alveolar bone is incomplete, and the stability of the implant is returned. The implant becomes weaker and less predictable. Therefore, in the fixture, it is possible to obtain an implant with higher predictability by performing sufficient fixation in the region serving as the fully coupled model and dispersing the stress concentration in the region serving as the partially coupled model.

  A further consideration is that it is desirable to avoid stress concentrations around the periphery of the fixture neck. In the fixture insertion model, stress is concentrated on the peripheral edge of the neck of the fixture, but the stress concentration is dispersed by moving the stress concentration to the deep part, that is, the apical side, and the marginal alveolar bone Can be protected. The boundary of the combination of the fully coupled model and the partially coupled model shown in FIG. In the fully connected model part, the stress is generated as a whole, and the physical property value contributes as it is.However, in the partially connected model part, the alveolar bone softens due to the breakdown in the minute part and the existence of the minute gap, and the load On the other hand, it becomes easy to displace. This is because stress concentrates on the boundary between the partially coupled model and the fully coupled model.

  From the above considerations, it is preferable that the fixture has a surface property that the collar side of the fixture is a surface property that is a partially coupled model, and that the apex side is a surface property that is a fully coupled model. I understand.

  In order to realize the surface property of the fixture serving as a partial bond model, the osseointegration phenomenon between the surface of titanium or titanium alloy and the alveolar bone can be used. The osseointegration between the surface of titanium or titanium alloy and the alveolar bone is widely recognized that there is a minute gap between the bone and the fixture, and has been confirmed by a micrograph of the joint.

  The surface of titanium or titanium alloy may form fine irregularities, and may be further subjected to alkali treatment. In order to form fine irregularities on the surface of titanium or a titanium alloy, surface treatment is performed using high-concentration hydrochloric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, nitric acid, or a mixed acid thereof. In addition, the alkali treatment is performed by heating the fixture after immersing it in an alkali solution of sodium hydroxide. As a result, a thin layer containing sodium titanate is formed on the fixture surface and has an abatite forming function.

  In order to realize the surface properties of the fixture, which is a fully coupled model, the surface of the hydroxyapatite is used. Hydroxyapatite is a bioactive material that actively attempts to bind to bone and is a component of teeth and bones made of calcium phosphate. It is said that 97% of enamel and 70% of dentin are composed of hydroxyapatite.

  The bond between hydroxyapatite and alveolar bone is called biointegration, and calcium is deposited and biochemically bonded to the alveolar bone. Hydroxyapatite and alveolar bone are directly connected by a calcium bridge. Bonding in almost all areas of the hydroxyapatite surface is promoted, and the bone formation rate is faster than that of titanium and directly bonds to the alveolar bone.

  This is because the mineral component of the alveolar bone is easily epitaxially grown on the crystalline calcium phosphate on the hydroxyapatite surface, the calcium phosphate dissolves, and the local calcium ion concentration increases, increasing the secretion of collagen that activates osteoblasts. This is thought to be because a large amount of protein that conducts osteoblasts adsorbs. Bone protein improves the adsorptivity with calcium phosphate, and the new bone produced by cells is mainly composed of hydroapatite. Therefore, it has crystallographic continuity with the hydroapatite on the implant surface, and the alveolar bone and the implant It will be directly coupled.

  However, the biocompatibility of hydroxyapatite is easy for bacteria of the oral cavity to attach, causing not only inflammation, but also producing acid, so that hydroxyapatite mainly composed of calcium phosphate in a low pH environment. May dissolve. In particular, hydroxyapatite coated on the metal surface causes problems such as dissolution and peeling of the coating film.

  It is thought that the decrease in pH around the implant is likely to occur when the presence of bacteria due to plaque adhesion to the fixture neck promotes acidification in the pocket or is inflamed by bacteria. For this reason, in HA implants with a hydroxyapatite surface coating, if the alveolar bone and the implant are not in close contact with each other, epithelial invasion may occur before bone formation takes place, and as a result, there is a possibility of dropping off due to fibrous encapsulation. Precision in ring drill formation is required.

  Furthermore, in order to prevent the invasion of bacteria, as well as to investigate the presence of inflammatory sites in the surrounding bone, in order to make the hydroxyapatite part coated with the fixture completely embedded in the alveolar bone, It took technology.

  In the present invention, the surface texture serving as a complete bond model is on the apex side of the fixture, and a hydroxyapatite coating portion exists in this portion. For this reason, since it is away from the neck side of the fixture, there is no plaque adhesion even if the fixture portion is not completely buried, and the invasion of bacteria is extremely reduced. This effect also provides long-term stability of the implant.

  In addition, even if it implement | achieves the area | region used as a partial bond model with the titanium or titanium alloy surface which has fine unevenness | corrugation, and the area | region used as a complete bond model performs alkali treatment on the titanium or titanium alloy surface which has fine unevenness | corrugation Good.

  As shown in FIGS. 1 and 2, in the present invention, in a dental implant, the fixture embedded in the alveolar bone has regions having different surface properties, and is separated into the apical side and the cervical side. It has a different surface texture region, and is characterized in that the bonding state with the alveolar bone that promotes osseointegration is different depending on the surface texture.

  The neck side of the fixture is titanium or a titanium alloy having fine irregularities on the surface, and the apex side is hydroxyapatite. The neck side surface may be treated with alkali. Since the stress can be concentrated on the boundary portions having different surface properties, the stress can be concentrated on a portion unrelated to the predictability, and an adaptive reaction of the alveolar bone in the portion can be expected. For example, according to the analysis result of FIG. 8, since it is considered that the vicinity of the center of the fixture, the boundary portion having a different surface property may be set to a position 1/3 to 2/3 of the fixture from the apex. preferable.

  Moreover, the neck side of the fixture is titanium or a titanium alloy having fine irregularities on the surface, and the surface on the apex side may be subjected to alkali treatment.

  The dental implant fixture according to the present invention can be manufactured by manufacturing the entire fixture as titanium or a titanium alloy having fine irregularities on the surface and coating the apical side with hydroxyapatite, or by alkali treatment. It is. For this reason, it is easily realized by coating the apex side with hydroxyapatite using the conventionally manufactured implant, or by treating the apex side with an alkali.

As mentioned above, although the Example of this invention was described, this invention contains the appropriate deformation | transformation which does not impair the objective and advantage, Furthermore, the limitation by said embodiment is not received.

DESCRIPTION OF SYMBOLS 10,26 Fixture part 12 Polishing part 14,14-1,14-2 Metal surface part 16 HA part 18 Fixture 20 Collar part 22 Guide protrusion 24 Apical part 30 Tooth cross section 32 Enamel 34 Cementum 36 Dentin 38 Dental pulp 40 Gingival 42 Adhered gum 44 Alveolar bone 46 Periodontal membrane 48 Root canal 50 Implant 52 Crown 54 Abutment 60 Analytical model 62 Restriction condition 64 Loading condition 66 Mises stress on alveolar bone 68 Bone resorption site 70, 72 Bone resorption site

Claims (7)

In dental implants,
The fixtures embedded in the alveolar bone have areas with different surface properties,
An implant characterized by.
The implant of claim 1, wherein
The surface texture of the fixture has different surface texture areas separated on the apical side and the cervical side, and the bonding state with the alveolar bone that promotes osseointegration depends on the surface texture. ,
An implant characterized by.
The implant according to claim 2,
The neck side of the fixture is titanium or a titanium alloy having fine irregularities on the surface, and the apex side is hydroxyapatite,
An implant characterized by.
The implant according to claim 3,
The neck side surface is treated with alkali;
An implant characterized by.
The implant according to claim 2,
The neck side of the fixture is titanium or a titanium alloy having fine irregularities on the surface, and the apex side is alkali-treated,
An implant characterized by.
The implant according to claim 3,
The entire fixture is composed of titanium or a titanium alloy having fine irregularities on the surface, and hydroxyapatite is coated on the apex side,
An implant characterized by.
The implant according to claim 6,
Hydroxyapatite coated on the apex side is that the apex side of the apex side is not coated with hydroxyapatite,
An implant characterized by.