KR810002115B1 - Dental and surgical implant material composition containing novel polycrystalline sintered ceramic - Google Patents

Abstract

Polycryst. sintered ceramic materials, useful in dental filling and prosthetic compns. were manufd. Thus, a soln. of 16.75g (NH4)2HPO4 in 400ml H2O and 150ml concd. NH3 was added over 20min to 130ml 1.63 N Ca(NO3)2 and 125ml concd NH3, boiled 10 min, cooled and filtered. The ppt. was heated to 1230≰C over 115 min and cooled to give a strong white ceramic material which had Ca-P mole ratio 1.62 and gave an x-ray diffraction pattern identical with that of hydroxylapatite.

Description

Prosthetic material composition containing novel polycrystalline sintered ceramic

The present invention relates to ceramics used in dentistry and orthopedics.

Many modern dental laboratories are focusing on the manufacture of materials that can be used as substitutes for teeth and bones, fillers, caps, crown tonics, and prosthetic fillers for bones.

The dental laboratory is also interested in the prevention of plaque caries and tissue diseases around the teeth.

Currently used dental fillers such as quartz, alumina, silicates and ultrafine microspheres have poor chemical or physical adaptability to tooth enamel. The main drawbacks of this material are exposure and tooth formation due to a mismatch of the linear expansion coefficient of the filler and tooth. Therefore, dentists have long expected dental fillers with natural tooth tissue and properties that are fully adaptable.

Moreover, even in the field of surgical prosthetics, the need for higher strength and non-corrosive alloying materials is approached, but the problem of tissue adaptability and adhesion has not been completely solved.

Research institutes focused on the development of effective anti-plague chemotherapeutic agents also require standard test materials with tooth-like tissue for both playcue formation and the persistence of chemotherapeutic agents. Although natural teeth can be used for this purpose, they are very variable and not available in large quantities and have the drawback of requiring precise cleaning before use. In conclusion, the use of other materials such as hydroxyl apatite, acrylic tooth, glass and wire increases the dental-platue. Although there are materials suitable for PlayCue formation studies, these materials are ineffective as anti-PLAYCUE agents because of their poor compatibility with natural tooth surfaces. For example, it is known that chemicals that inhibit Playcue formation on teeth do not require glass and wire. Thus, there is a need for a chemically similar, inexpensive, easily available, highly polished tooth enamel.

Hydroxyapatite Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ , known as calcium oligophosphate as a tooth and bone mineral, has been reported to be widely applicable for this purpose, and US patents have already specified their preparation methods. . These materials are used by mixing a synthetic resin as an external composition. However, these processes not only have the time-consuming, laborious and limited drawbacks of pulverizing hydroxyl apatite, but the method must be changed according to the availability of natural teeth.

Gooder presented in the literature a mixture of White lockite and hydroxyl apatite produced by the separation of powdered hydroxyl apatite at various temperatures.

Bett and his colleagues produced a special hydroxyl apatite that changed the stoichiometry of calcium and phosphorus from 1.67-1.57, which contained large coral crystal pores.

They also reported that heating calcium-deficiency hydroxyl apatite to 1000 ° C. causes a partial transition and changes to the hydroxylite state.

US patents disclose bone and dental enhancers consisting of refractory and calcium phosphate compounds, namely white rockite. Several attempts have been made to produce rigid yet tough super-hydroxyl apatite, but no satisfactory results have been obtained. Roy and Linnehan then proposed a hydrothermal conversion method that could convert calcium carbonate in the undersea coral bone into hydroxyl apatite. The material thus produced possesses many of the pore properties of the coral structure and also has a low tensile strength (270-470 psi) but has many drawbacks as a guarantee.

Monroe and his colleagues reported the manufacture of ceramic materials by sintering of compressed hydroxyl apatite. The material thus made is a multifaceted crystal of the ordered matrix, consisting of Ca ₃ (PO ₄ ) ₂ or tricalcium phosphate, a mixture of hydroxyl apatite and about 30% α-whitelockite, which can be used for dentures. There are so many pores.

Lao and Bohem announced the preparation of polycrystalline hydroxyl apatite by isothermal sintering of powdered hydroxyl apatite in a mold and then in the form of a mold. The ceramic thus made is porous and has a maximum compressive strength of about 17,000 psi.

Baskar and his colleagues announced the use of calcium phosphate ceramic materials necessary to meet bone deficiency.

The material is very porous and reabsorbed from the implant site and has a lower strength than metal or non-disintegrated ceramic implants.

In short, the present invention relates to a method in which the molar ratio of calcium and phosphate reacts calcium and phosphate ions in an aqueous medium at pH 10-12 to produce a solid phase precipitate of phosphate, and then the precipitates are separated from these solutions, followed by Is heated to a temperature below the decomposition temperature of at least 1000 ° C. to the highest hydroxyl apatite, and the above temperature is maintained for a sufficient time so that the final product is effectively calcined and densified to the maximum. To provide.

According to another aspect of the present invention, the present invention provides a novel ceramic-type hydroxyl apatite composed of hard, dense and glossy hydroxyl apatite. These materials are chemically very similar to tooth enamel. Moreover, the novel materials of the present invention are superior to natural teeth because of their low quality starting materials, which can be prepared by a relatively simple method and their uniform quality. Mixing the new hydroxyl apatite in ceramic form with the dental tonic composition yields a dense filler having substantially the same coefficient of expansion as natural tooth enamel.

The dental and orthopedic implant materials according to the present invention are hard, tough and fully adaptable to living bodies, and can be produced in desired shapes without the need for high pressure or other subtle techniques. Moreover, since the necessary porosity can be given as described below, the penetration growth in the tissue is possible.

The novel materials prepared by the method of the present invention facilitate the manufacture of discs, plates, rods, and the like for dental anti-PlayQ agent testing.

According to yet another aspect of the present invention, the present invention provides a novel biphasic ceramic material composed of hydroxyl apatite and white rockite. As described below, the biphasic ceramics of the present invention are not only hard, dense, non-porous, bio-adaptable, but also easily manufactured in desired shapes and shapes. It is also useful as a resorbable surgical implant material by resorbability.

The porosity in the surgical implant material promotes circulation of body fluids and penetration growth in tissues but reduces the mechanical strength of the implant. The biphasic ceramics provided by the present invention are dense, mechanically robust and non-porous, but because the white rockite phase contained therein is slowly absorbed from the implant and replaced by natural hard biological tissues, Excellent circulation and penetration growth in tissues. The novel hydroxyl apatite of the present invention is a white crystalline sintered ceramic material whose physical form differs from the biological, geological form and the known synthetic forms described below, which is an average of 0.2-3μ. It is composed of hydroxyl apatite with particle size and density of 3.10-3.14g / ㎠, but it has no pores and has the characteristic of splitting along smooth curved plane. In addition, the material has a compressive strength of about 35,000-125,000 psi tensile strength of about 3,000-30,000 psi linear expansion coefficient of about 10-12ppm / ℃, Knoop hardness of about 470-500, elastic modulus like the material prepared by the conventional method It is about 6 × 10 ⁶ psi and does not birefringe under extreme light. According to the initial evaluation of the hydroxyl apatite mentioned above, the novel hydroxyl apatite ceramic of the present invention is composed of irregular and isotropic microcrystalline pure hydroxyl apatite, and its compressive strength is about 35,000-75,000psi, tensile strength 3,000-50,000psi Linear expansion coefficient is about 10-12ppm / ℃, Knoop hardness is 470-500, Elastic modulus is 6 × 10 ⁶ psi, and it is cut along smooth curved plane and does not birefringence under extreme light.

As used herein, the term "dense" means that the arrangement of particles is very dense so that there is no space or unfilled gap. Compared to the above-mentioned ceramics of the present invention with geological hydroxyl apatite and synthetic hydroxyl apatite prepared by hydrothermal method, the latter has huge crystals and breaks along the plane and is birefringent.

Generally, ecological hydroxyl apatite contains a large amount of carbonate ions in the apatite lattice in the pure state, ie, tooth enamel, and is anisotropically arranged in the spiral rod, so that the straight line along the interface of these enamel rods It ruptures and has a relatively low tensile strength (1500 psi).

In addition to the above-mentioned properties of the novel hydroxyl apatite in the ceramic form of the present invention, it is very suitable as a dental and surgical tonic because of its excellent bio-adaptability. Therefore, the ceramic of the present invention can be molded or machined to dentures, tooth crowns, artificial bones, stiffeners, cannulae and canals and prostheses for dental prostheses and dental play cue-cavity type arthritis and teeth and bones. It can be used as a test surface for researching other diseases that may occur. The novel ceramics of the present invention, suitably ground, can be used as a dental reinforcement by mixing with synthetic canncellus bane, abrasives and standard resins to treat fractures.

As the test data of the dental play cue inhibitor, the ceramic of the present invention can be manufactured into a size and shape that can be easily inserted into a standard test tube, and inserted into the body. This is easily accomplished by cutting or machining the dry filtration caking to a desired size and then firing. A highly pore sintered product as gemstone was used as a substrate for testing the dental-play cue inhibitors according to the process described by Treski and his colleagues. After the test, the ceramic material is simply reworked to obtain a new test surface.

Like conventional products, the ceramics of the present invention are essential for dentistry because they are compact and non-processable. The ceramic of the present invention may change porosity by the method proposed by Monroe and his colleagues. That is, the porosity can be changed by sintering organic substances such as starch, cellulose, cotton or collagen at 5-25 wt% in the solid phase precipitate of hydroxyl apatite. Another method of generating porosity is to mechanically drill holes in non-porous ceramics.

In this way dentures made from the ceramics of the present invention are porous in terms of implantation but the exposed denture surface remains non-porous. This equation can be achieved by the method reported by Hodosch and his colleagues. The ceramic provided by the present invention can be used as a coating material for metal grafting when mixed with a polymerizable or polymerized binder as described below.

A second aspect of the present invention is to provide a tough, hard, dense, white, isotropic, polycrystalline-sintered ceramic composed of 14-98 wt% hydroxyl apatite and 2-86 wt% hoytlockite, which is free of pores and smooth curved planes. It has the characteristic of cutting along. Whitekite, known as tricalcium phosphate, is an inorganic substance with the formula cca ₃ (PO ₄ ) ₂ , which is present in the crystal phase of α or β. As used herein, white rock kite means an α or β phase or a mixture of both phases.

The biphasic ceramics of the present invention exist as non-porous polycrystalline materials regardless of the relative concentrations of hydroxyl apatite and white rockite contained therein. However, since the hydroxyl apatite and the white rockite have the above-described physical properties, the physical properties of the biphasic ceramics, that is, the density and the optical property, vary depending on the relative amounts of the hydroxyl apatite and the white kite contained in the ceramic. For example, because the theoretical density of whiteloxite is less than that of hydroxylapatite, the density of biphasic ceramics composed of 40wt% hydroxylapatite and 60wt hydroxylkite is 2.98g / cm 3, but pure hydroxylapatite ceramics 3.10 g / cm 3.

The biphasic ceramics mentioned above are well suited as surgical tonics because of their bio-application. Therefore, the material can be made into a shape that can be filled by a mold or a machine to fill voids or defects in the bone, or a shape of a bone or a joint. The white rock kit contained in the artificial product made of the biphasic ceramic is reabsorbed and replaced by the internal penetration growth of hard tissues of natural organisms. Of course, the degree of internal growth of the tissue depends on the amount of absorbent white rock kit contained in the ceramic.

Like conventionally manufactured products, the biphasic ceramics of the present invention are non-porous. However, if desired, a desired porosity can be provided in the ceramic.

Biphasic ceramics can also be converted to acid resistant materials by fluorination.

The novel ceramics of hydroxyl apatite mentioned above precipitate hydroxylated apatite having a calcium diphosphate ratio of about 1.62-1.72 in a pH 10-12-aqueous medium, and then separate the precipitated hydroxylapatite from solution to decompose them. It can be prepared by heating for a time sufficient to achieve maximum densification while sintering the hydroxyl apatite at an unheated temperature.

Hydroxyapatite is precipitated from an aqueous medium by reacting calcium ions with phosphate ions at pH 10-12. Calcium or phosphate-containing substances that produce calcium and phosphate ions in aqueous media easily separate their respective counter ions from the hydroxyl apatite product, but they do not mix with each other in the lattice of hydroxyl apatite or precipitate pure hydroxysin apatite. Or interfere with isolation. Materials capable of providing calcium ions are calcium nitrate, calcium hydroxide, calcium carbonate and the like. According to the method of the present invention, calcium nitrate and diammonium hydrogenphosphate are very suitable materials as calcium and phosphate sources.

The manufacturing method of the hydroxyl apatite of this invention is as follows.

First, the mixture of calcium nitrate and diammonium hydrogen phosphate in a molar ratio of 1.67-1 is mixed and then reacted with each other in an aqueous solution of pH 10-12 to form a gelatinous precipitate of hydroxyl apatite. The method proposed by Hayek and his colleagues is very suitable for this purpose. The colloidal suspension of hydroxyl apatite thus obtained is then left in the raw solution for a sufficient time until the calcium to phosphate ratio is about 1.62-1.72. These operations are readily accomplished by stirring the suspension for less than 24 hours at room temperature or by boiling the suspension for 10-90 minutes or otherwise by boiling and then left at room temperature. It is best to let the suspension boil for 10 minutes and then leave it at room temperature for 15-20 hours.

The hydroxyl apatite is then separated from the solution by a suitable device such as a centrifuge or vacuum filter.

The hydroxyl apatite absorbed in the large amount of water thus obtained is pressurized. If necessary, the damp clay material thus obtained may be cut into desired shapes or cast into suitable molds. The moist hydroxyl apatite undergoes about 25% contraction upon drying and about 25% contraction even when calcined by the method described below. Of course, it is necessary to cut or mold in consideration of this phenomenon. The moistened molding is slowly heated to a firing temperature of 1050 ° C.-1250 ° C. to remove all remaining moisture. A stay of about 20 minutes to 3 hours at a temperature of 1050 ° C.-1250 ° C. completely sintered the molding to maximize densities. Usually, it is good to separate only the molded product dried just before predetermined | prescribed baking. Therefore, moist moldings should be dried at 90-900 ° C for 3-24 hours or until the water content is 0-2%. The most common optimum drying condition is drying at 90-95 ° C. for 15 hours or until the water content is reduced to below 1-2%. The hydroxyl apatite obtained in this way is brittle and porous but has significant mechanical strength. When the thick filter cake is dried, the clay-like material is often separated or cracked during drying. However, flaky moldings having an area of 100 cm 2 and a thickness of 3 mm are relatively less likely to separate or crack. To reduce or eliminate the separation or cracking during drying, collagen, cellulose or cotton powder should be added to the precipitated hydroxyl apatite at 0.4-0.6 wt%, especially 0.5 wt%. The organic binder does not change the physical properties of ceramic products because it is volatilized upon firing.

Of course, using a large amount of organic binder produces a porous ceramic product. Other organic and inorganic binders known in the ceramic art can also be used in the present invention.

In this step, it is preferable to prime the dried hydroxyl apatite in the desired form in view of the shrinkage occurring during firing.

The body of the hydroxyl apatite immediately before firing shall be uniform and free of defects. Cracks or defects cause breakage during firing. The product is then calcined at a temperature of 1050 ° C.-1250 ° C. for about 20 minutes to 3 hours. However, the temperature and time at this time is inversely related. Firing operation is preferably carried out for 0.5-1 hours at a temperature of 1100 ℃ -1200 ℃. The dense hard ceramic thus produced is cut or machined in a conventional manner.

In the above process, it is common to prepare a colloidal precipitate of hydroxyl apatite in a colloidal state which can be molded or molded into a hydroxyl apatite and then sintered into a very large ceramic. Granulated or powdered dry hydroxyl apatite cannot be reshaped into a sticky colloid. For example, when powdered hydroxyl apatite is suspended in water and filtered in a non-tacky state, it cannot be molded, ie, molded or converted into the form of a ceramic. Furthermore, even if the powdered hydroxyl apatite is molded by mechanical tableting and fired by the present invention, it is dispersed in three pieces without being cut along a highly porous and smooth curved surface.

The cause of the formation of hydroxyl apatite in an aqueous medium is too complex to precisely identify, but it is presumed that calcium and phosphate ions first combine to form calcium-poor hydroxyl apatite with an calcium to phosphate ion ratio of about 1.5. . In the presence of calcium ions the material is slowly transformed into hydroxyl apatite with a calcium to phosphate ratio of 1.67. Therefore, in order to obtain a ceramic composed of pure hydroxyl apatite, the process of the present invention must be run so that the gelatinous precipitate of the hydroxyl apatite is in contact with the raw solution for a sufficient time so that the ratio of calcium to phosphate is 1.62-1.72. Outside this range, ceramic products with weak transparency are obtained. For example, if the hydroxyl apatite is precipitated at room temperature for 2 hours to maintain the ratio of calcium to phosphorus at 1.55-1.57, the ceramic becomes opaque. In essence, materials having a ratio of calcium antiphosphorus of 1.44-1.60 are useful for producing the ceramics of the present invention. Therefore, as the transparency of pure hydroxylapatite ceramics produced by the method of the present invention, it is easy to estimate the stoichiometry of calcium to phosphorus and whether the product upon firing is composed of pure hydroxylapatite. This allows the hydroxyl apatite suspension to separate the integers and allow elemental and X-ray analysis of the dry firing in the above-mentioned method.

The firing period and temperature are not limited only to the scope of the claims. Therefore, unfired hydroxyl apatite having a calcium to phosphorus ratio of 1.62-1.72 can be converted to the ceramic of the present invention by heating to a temperature of at least 1050 ° C-1200 ° C. The time required for complete firing and maximum densification at 1050 ° C. is 2-3 hours, but 20-30 minutes at 1200 ° C. In fact, firing for about 1 hour at a temperature of 1100 ℃ is sufficient. Firing at temperatures below 1050 ° C. results in incomplete firing, while firing at temperatures above 1250 ° C. for more than one hour results in partial decomposition of hydroxyl apatite into white rock kites.

The above-mentioned biphasic ceramics composed of hydroxyl apatite and white precipitate calcium phosphate compounds with a calcium to phosphorus ratio of approximately 1.44-1.60, particularly preferably 1.46-1.57, from an aqueous solution having a pH of 10-12 The precipitate can be prepared by separating it from the aqueous solution and heating it for a sufficient time at a temperature sufficient to cause calcination and maximum densification.

Calcium phosphate compounds having a calcium and phosphorus ratio of 1.44-1.60 are prepared by the interaction of calcium ions and phosphate ions in an aqueous medium at pH 10-12 using the calcium and phosphates mentioned above for the production of single-phase hydroxyl apatite. Obtained. Calcium nitrate and diammonium hydrogen phosphate are the most suitable reagents for this purpose.

Therefore, biphasic ceramics react with each other at a molar ratio of calcium nitrate and diammonium hydrogen phosphate of 1.67-1, that is, they are left in the raw solution within 4 hours without heating the initial colloidal precipitate. It can be produced by the above-mentioned method for producing a single-phase ceramics or left to the range that the molar ratio of calcium to phosphate does not exceed 1.60.

As described in the preparation of single-phase ceramic hydroxyl apatite, calcium phosphate precipitates are separated and washed from the raw solution, and then molded or molded into desired shapes, but if necessary, drying and isolation are carried out before firing.

The newly precipitated calcium phosphate suspension can also be treated with an organic binder or fluorine ion as mentioned in the preparation of single-phase hydroxyl apatite.

Firing is effectively achieved by heating for 20 minutes to 3 hours at a temperature of 1050 ° C-1350 ° C. The amount of white rockite contained in the ceramic thus produced depends on the time required to separate the precipitate from the stock solution, which is typically 2-83%. For example, calcined precipitates with a ratio of calcium to 1.55 were calcined in ceramics separated in 5 minutes, which contained about 82% of white rockite. If the product is separated after 2 hours of precipitation, the calcium-to-causter ratio is 1.57, and the ceramic fired from this material contains 61% of white rockite. After 4.5 hours of precipitation, the precipitate was separated and a ceramic containing about 2% white rockite was obtained. X-ray analysis shows that this is the lowest concentration of white rockite. Of course, even if the product is in contact with the stock solution for about 7 hours, the ceramic obtained is single-phase hydroxyl hydroxyapatite.

The biphasic ceramics provided by the present invention can be prepared by reacting the molar ratio of calcium and phosphate ions at 1.50-1.60 to 1. In this case, the molar ratio of calcium to phosphate in the calcium phosphate precipitate can be less than 1.60 by changing the contact time of the stock solution and the precipitate.

Therefore, the method for producing the biphasic ceramics described in the claims has a molar ratio of calcium nitrate and diammonium hydrogen phosphate in the reactants to produce a ceramic composed of 30-50% hydroxyl apatite and 50-70% white rockite. Can be easily proceeded by the method described in the preparation of single-phase ceramic hydroxyl apatite except that is maintained at 1.50-1.60 to 1.

Ceramics are white rockite by appropriately combining two processes, ie, a molar ratio of calcium ions and phosphate ions of 1.50-1.60 to 1 and maintaining a aging time of precipitated calcium phosphate compounds at 5 minutes to 4 hours. You can increase the component of. The ceramic thus made consists of about 10-30% hydroxyl apatite and 70-90% white rockite.

Since hydroxylapatite is converted and decomposed into white rockite at 1250 ° C, when the single-phase ceramic hydroxylapatite of the present invention is heated at a temperature of 1250 ° C or higher for a long time, the above-described hydroxylapatite is partially decomposed into whitelockite.

The present invention also provides a dental tonic composition composed of a mixture of the ceramic hydroxylapatite of the present invention and a polymerized tablet or polymerized binder which is adaptable to oral conditions. The dental tonic composition of the present invention is composed of 10-90 wt%, particularly preferably 60-80 wt% of fine ceramic hydroxyl apatite and the remaining amount of 10-90 wt% of a polymerizable composition, wherein the polymerizable composition is an aliphatic ketone peroxide. , Polymerization catalysts such as benzoyl peroxide, di-tri,-and tetra-ethylene glycol dimethacrylate and a polyvalent reaction solvent, curing agents such as N-3-oxohydrocarbon-substituted acrylamides, and metal acetyl acetonates. And tertiary amines such as N, N-bis- (2-hydroxymethyl) -P-toluidine, and the like, and polymerizable materials capable of polymerization by crosslinking agents such as zinc oxide.

The amount of additive in the polymerization composition is 0.01-45wt% of the precursor composition. Although not required, the interface is a reaction product of N-phenylglycine and glycidyl methacrylate, methacryloxypropyltrimethoxysilane, 3,4-epoxycyclohexyl ethyltrimethoxysilane, vinyl trichlorosilane, and the like. Active comonomers may be added to the composition in the range of 0.05-10 wt% of the total composition. The binder increases the binding strength of the ceramic material to the resin and the dental filling composition to natural teeth. Therefore, the ceramic hydroxyl apatite provided by the present invention can be used by mixing an appropriate amount of a resin known for dental tonic, after granulating to a size of 5-100 microns by a conventional grinding method.

Known resins that can be used for this purpose are propyleneglycol flurate mate unsaturated glyceride glycide glide commercially available under the trade names of hydroxylethyl methacrylate, polymethyl methacrylate, polyacrylic acid, 23LS8275 and Selectron 580001. Epoxy resins such as styrene modified unsaturated polyester Ciba araldite 6020, Union Carbide ERL2774 and bisacrylate monomers made from glycidyl methacrylate and bisphenol A such as POL 1008, G-136 and 4CS50.

The resin may be composed of a monomer, a mixture of weights or higher monomers. Additives such as dye inorganic pigments and fluorescent dyes may be added to the composition based on the theory known in the art. Mixtures of resins, ceramic hydroxylapatite and suitable additives such as silane binders, dye inorganic pigments or fluorescent agents are preferably mixed before adding the catalyst, curing agent, crosslinking agent and accelerator. However, since the order of addition is not important, the above additives may be mixed at the same time. Using a conventional method, the composition prepared by the above method is cast into a suitable mold so as to be a denture or a set of dentures and used as a tooth filler, a tooth cement, a cavity liner, a pulp capping agent. Can be used.

Of course, the materials used should be anti-cavities in the oral cavity. In the practice of the present invention, dental caries prevention is easily accomplished by mixing fluorine ions such as ammonium or stenosulfide with 0.01-1% of the newly precipitated hydroxyl apatite suspension. The ceramic of the present invention produced by firing is excellent in resistance to acetic acid, acetic acid or citric acid. Tooth decay can also be imparted by exposing the porous ceramic material to a 5% aqueous sodium fluoride solution for 12 hours to 5 days. In practice, the ceramic body is immersed in 5% aqueous sodium fluoride solution for about 4 days.

Of course, the ceramic material provided by the present invention may be added to the organic and inorganic binders and fluorine ions, as well as to the appropriate materials within the limit that the properties of the ceramic product do not change and impart useful properties to the ceramic. For example, it is known that the penetration of inorganic materials such as barium and strontium into the apatite crystal lattice is more opaque to X-rays than calcium. Therefore, the addition of barium or strontium ions to calcium ions prior to lattice reaction with phosphate ions results in the formation of hydroxyl-pattern coated with barium or strontium, which can be used as an X-ray absorbent for filling teeth and as a dental tonic composition. . Mixing magnesium with the apatite crystal lattice delays the crystallization of hydroxyl apatite, but promotes the crystallization of white rockite. Therefore, adding a small amount of magnesium to calcium ions before lattice reaction with phosphate ions produces a large amount of white rockite, resulting in a biphasic ceramic containing a lot of white rock kite.

Ceramic materials prepared by the methods described above have properties in terms of elemental analysis, density, X-ray diffraction, electron permeability, extreme light and mechanical properties.

Hereinafter, the present invention will be described in more detail with reference to the following Examples.

Example 1

To a homogeneous mixture of 130 ml (0.212 mol) of 1.63 N calcium nitrate and 125 ml of ammonia, a mixture of 16.75 g (0.127 mol) diammonium phosphate distilled water and 150 ml of ammonia was added dropwise over about 20 minutes. The resulting suspension is boiled for 10 minutes, cooled in an ice bath and filtered. The filter binder is pressed with a rubber sheet, and then dried one night at 95 ° C. The hard, porous and brittle binder thus obtained is heated in an electric furnace for 115 minutes until the final temperature of 1230 ° C. and then cooled to room temperature yields a tough, hard and transparent white ceramic product.

Elemental analysis of the final ceramic product and the dried hydroxyl apatite before firing on the basis of the formula Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ is as follows.

The flake test of ceramics under extreme light microscopy reveals no white rockite. The absence of birefringence and recognizable structural properties such as crystalline shape, orientation, interface and the like are represented by the microcrystalline structure. A microscopic comparison of the flakes of the tableted plastics reported by Monroy and his colleagues and the ceramics of the present invention showed different structures of the two materials.

X-ray diffraction was measured by a conventional method. Computation of the planar mutual spacing is equal to the planar mutual spacing of hydroxyl apatite reported by Donnai and his colleagues. X-ray data indicate that there is no greater amount of white rockite than 2-3%.

Example 2

A solution containing 79.2% (0.6 mol) of diammonium hydrogen phosphate in 1500 ml of distilled water was adjusted to pH 11-12 by adding about 750 ml of concentrated ammonia.

To dissolve the precipitated ammonium phosphate, distilled water was added as an additional portion to make the total amount 3200 ml. If necessary, adjust the pH back to 11-12. The solution thus obtained was added dropwise to 30 ml of concentrated ammonia water in a solution of 1 mol of calcium nitrate in 900 ml of distilled water previously adjusted to 12, under stirring for 30-40 minutes, and diluted with 1800 ml of distilled water. After the completion of the stock price process, a colloidal suspension is formed. After stirring for 10 minutes, the mixture is boiled for 10 minutes, the heat source is removed, the lid is closed, and left at room temperature for 15-20 hours. Decant the supernatant and centrifuge the residue at 2000 rpm for 10 minutes. The sludge thus obtained is re-suspended in 800 ml of distilled water and then centrifuged at 2000 rpm for 10 minutes. Add enough liquid to the residual solid to make 900ml. The solution is stirred vigorously to avoid large condensation or aggregates. The whole suspension is poured into the Buener ring at once and filtered using mild depressurization. If the filter binder starts to crack, the degree of vacuum is increased after using the rubber plate.

After an hour, the rubber plate was removed, and the crack-free filtration binder was transferred to a flat surface and dried for 15 hours at 90 ° -95 ° C. to obtain 90-100 g of white flakes of porous and brittle hydroxyl apatite. Fragments with an area of 1-4 cm 2 free of cracks or cracks are placed in an electric furnace, and the temperature is gradually raised to 1200 ° C. over 100 minutes, and then the contents of the furnace are cooled to room temperature after a certain period of time. This results in a translucent ceramic that is hard, dense, non-porous and white.

As a result of successive analyzes, it was found that the assays used could not fully explain the samples and that these results were inaccurate and very variable. Despite the above analytical data, the homogeneity of the sample was confirmed by the following electron microscope. Furthermore, the product of Example 3, prepared in exactly the same process as in Example, had the expected analytical results and was found to be homogeneous hydroxyl apatite by X-ray diffraction and electron microscopy.

The clodion copy on the sample surface was shaded with chromium and carbon to create a two-stage radiation sample. Examining the two samples with an electron transmission microscope at the minimum sensitivity sensitivity of the electron microscope results in a uniform particle size with no precipitates or pores of 0.5% or more of the second phase in the particle interface or particles themselves. The ceramic sample is polished to 600 grit on silicon carbide paper and then to 3 micrometer diamond on a metal plate coated with a fine nylon cloth. The sample is then corroded with 4% hydrofluoric acid for 30 seconds. Make a copy of the polished and corroded surface and observe it with an electron microscope. Although no second phase was observed at the grain boundary, it was confirmed that a small amount of the second phase was present in the particle.

Compressive strength and modulus of elasticity are measured by conventional methods, respectively 56,462 psi ± 16,733 psi and 6,3 × 10 ⁶ psi. Tensile strength measured by three-point bending standard test shows 9,650 psi ± 3,320 psi. The linear coefficient of thermal expansion between 25 ° C. and 225 ° C. is 11 × 10 ⁻⁶ / ° C. ± 10%.

It was found by the standard Knoop test method that the hardness was 480. The same result can be obtained by changing the direction of the external force, so the material is isotropic.

The porosity was measured by impregnating the test substance with hooksin dye for 15 minutes, washing with water, drying and irradiating the dye remaining on the test substance. This test was conducted simultaneously with samples of non-porous ceramics, compressed plastics of hydroxyl apatite and natural teeth provided by the present invention. Compressive firing showed a significant residual phenomenon of the dye, but the new ceramic and natural teeth of the present invention did not show any residual phenomenon of the dye. As another method, the test material was impregnated in 6N aqueous ammonia solution for 15 minutes, washed with water and dried, and then the surface moisture was examined with litmus paper. The ammonia remaining in the surface pores discolors the litmus paper. When the above test is performed on the ceramic, hydroxyl apatite compressed natural material and the natural tooth of the present invention, the compressed plastic material changes the litmus test paper to blue, but the novel ceramics and natural teeth of the present invention do not form the litmus test paper.

Example 3

When the process described in Example 2 was carried out using 3 moles of potassium nitrate and 1.8 moles of diammonium hydrogen phosphate as a starting material, brittle, porous white hydroxyl apatite was obtained.

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Firing the material at 1100 ° C. for 1 hour yields a hard, white, semi-permeable ceramic whose density is 3.10 g / cm 3. X-ray diffraction shows the material as homogeneous hydroxyl apatite. Electron microscopy showed that the material had a particle size in the range of 0.7-3 microns and had no pores or secondary phases.

Example 4

A. About 50 g of hydroxylapatite was precipitated from an aqueous solution using only half of the amount used in the process described in Example 2. After centrifugation, the supernatant was decanted and the residual sludge was re-suspended in water to make 1 L exclusively and homogenized in a Waring mixer for 2 minutes.

B. Mix for 3 minutes in a waring mixer in which 0.5 g of cellulose powder (<05 μ) was dissolved in 200 ml of water. 100 ml of homogeneous aqueous solution of hydroxyl apatite was added to the stock, followed by further mixing for 5 minutes. The suspension is filtered and the filter binder is dried and calcined by the method of Example 2. The filter binder after drying showed very small cracks, but the fired ceramic product was slightly porous as indicated by the test with the hooksin salt mentioned above.

C. Mix 200 ml of water containing 0.5 g of chopped surgical cotton in a Warring mixer for 45 minutes or until a uniform suspension is obtained. Add 100 ml of the homogeneous suspension of hydroxyl apatite described in Example 4A, and mix again for 15 minutes. The suspension thus obtained is filtered, the filter binder is dried and calcined according to the process of Example 2. The ceramic product made in this way is noticeably porous.

Example 5

A. Mix 300 g of water containing 5 g of collagen in a Waring mixer for 5 minutes. Collagen absorbs large amounts of water and turns into a colloidal substance. Small amounts of fine collagen (20-30 mg) are present in the suspension.

B. The supernatant of the fine collagen suspension (250 ml) is decanted and mixed for 5 minutes in a Waring mixer with 100 ml of a solution of the hydroxyl apatite described in Example 4A. The mixture thus obtained is filtered, the filter product is dried and then calcined according to the process of Example 2, and the ceramic product is non-porous.

C. Mix approximately 20% of the colloidal collagen with the homogeneous suspension of hydroxylapatite described in Example 4A in a Waring mixer for 6 minutes. The mixture thus obtained is filtered, the filter binder is dried and calcined by the method of Example 2. Filtrate before firing remains intact and maintains significant mechanical strength. The ceramic produced by firing is hard, rigid and noticeably porous.

Example 6

A sample of the ceramic product prepared by the method of Example 2 was left in a 1% aqueous sodium fluoride solution for 12 hours. The material is exposed to 10% lactic acid with untreated ceramic and natural tooth samples.

After 3 days, fluorinated ceramics show less attack by lactic acid than untreated ceramics and natural tooth enamel.

When the ceramic is left in an aqueous 1% sodium fluoride solution for 3 days, it is hardly attacked by lactic acid for 3 days and slightly decomposed by lactic acid attack for 1 month, but the untreated sample is severely decomposed.

Example 7

According to the process described in Example 2, about 50 g of hydroxylapatite was precipitated from the aqueous solution by reducing the amount used therein by half. After centrifugation, the sludge was suspended in water to make the whole amount to 500 ml. The suspension was divided into 10 portions and diluted with 50 ml of water and treated with ammonium fluoride as follows. Samples 1,2,3,4,5 and 0,00085 g. 0, 0.1, 0.5, 1.0, and 2.0 ml of aqueous ammonium fluoride solution containing F ^Q / ml were added, respectively. Samples 6, 7 and 8 were treated with 0.5, 1.0 and 10.0 ml of aqueous ammonium fluoride solution containing 0,0085 gF ^Q / ml.

Samples 9 and 10 were stocked with 2.0 and 4.0 ml of aqueous ammonium fluoride solution containing 0.045 F ^Q / ml, respectively. These suspensions were shaken on a rotary shaker for 1.5 hours and then filtered. The filtrate was pressed with a rubber plate for 15 minutes, dried at 95 ° C. for 2 days, and then heated in an electric furnace at a temperature of 1200 ° C. The ceramic thus produced was pulverized and sieved to 325 mesh sieves. 80 mg of each powder sample was mixed with 80 ml of lactic acid buffer (0.4 M) at pH 4.1 and shaken on a shaker shaker. Every 2, 9, 25 and 40 minutes after mixing, 3-ml from each sample mixture was immediately filtered to remove insoluble samples and the amount of dissolved ceramic was measured by standard colorimetric method. The results are shown in Table A. For comparison, the sinter of Sample 1 was left in 1 ml of 5% sodium fluoride for 4 days. The solids were removed, washed well with water, and then dried and tested for dissolution as in Sample A. The results are also shown in Table A. Of course, the experimental conditions mentioned above are not an accurate method, but since the samples are allowed to dissolve for a sufficient time, the relative effect of the fluorine ion concentration can be accurately determined. Therefore, the standard dissolution rate of ceramic hydroxyl apatite is expected to be significantly slower than the rate in the strong lactic acid buffer observed above.

TABLE A

Example 8

A dry filtration binder having Ca / p = 1.64-1.663 and a thickness of 3-4 mm was made by the method of Example 2, which was cut into square plates having a length of 14-15 mm and a width of 7-8 mm, and then a small hole at one end. Pierced The plate was calcined at 1000 ° C. following the process of Example 2 and highly polished using a jeweler.

This yields a square plate ceramic with a density of 3.12-3.14 g / cm3 and a length of 10-11 mm, a width of 4-5 mm, and a thickness of 2-3 mm, with holes at one end that pass through the wire. The plate was placed in a test tube to a predetermined depth and tested for dental playcue inhibition as mentioned above.

Example 9

A solution containing 0.24 mole of diammonium hydrogen phosphate in 600 ml of distilled water was adjusted to pH 11.4 with 340 ml of concentrated ammonia water and distilled water was added to make a total volume of 1280 ml. 0.4 mol of calcium nitrate was dissolved in 360 ml of distilled water previously adjusted to pH 11 with mont- ammonia water, and distilled water was added dropwise while stirring the solution to 720 ml of the total solution. The suspension thus prepared was stirred without boiling, and then 250 ml of water was collected periodically to separate the product, followed by washing with water and drying by the method of Example 2. All samples were heated at 1100 ° C. for 1 hour and the composition was measured by X-ray diffraction. The results are shown in Table B.

TABLE B

Example 10

A. The process of Example 2 using 0.3 mole of calcium nitrate and 0.2 mole of diammonium hydrogen phosphate yielded a hard, brittle porous product with the following elemental composition: Ca = 38.85%; P = 19.77% Ca / P = 1.52

Heating the material at 1200 ° C. for 1 hour yields a hard, tough, non-porous, somewhat opaque, white ceramic material consisting of about 40 hydroxyl apatite and 60% white rockite.

B. When the reaction proceeds by changing the order of addition of starting materials, a product is obtained with Ca / p = 1.52, density 2.982 g / cm 3, composition 40% hydroxyl apatite and 60% white rockite.

Example 11

The solution containing 0.0625 mol of diammonium hydrogen phosphate in 150 ml of distilled water was treated with 95 ml of concentrated ammonia water, and distilled water was added again to make 320 ml of exclusive volume. The solution was slowly added dropwise to a solution containing 2.5 ml of concentrated ammonia and 0.1 mol of calcium nitrate in 180 ml of distilled water over 30 minutes. The suspension thus obtained is stirred for 5 minutes, cooled in an ice bath for 45 minutes, and the suspended solids are separated and washed and dried in the same manner as in Example 2 to obtain a hard, brittle, porous white solid having the following composition. Ca = 35.4%; P = 18.59 Ca / p = 1.46. Heating the material at 1350 ° C. for 1 hour yields a hard, tough, nonporous, somewhat opaque ceramic product consisting of 14% hydroxyl apatite and 86% hydroxylkite.

The product of Examples 1-11 produced by the manufacturing process of the present invention has the physical properties as described below.

The products of Examples 1,2,3,5 B and 6,7,8 are hard, tough, dense, translucent and white ceramics composed of pure isotropic polycrystalline hydroxyl apatite without pores, with a compressive strength of about 35000 -125,000 psi, tensile strength of about 3,000-30,000psi, linear thermal expansion coefficient of about 10-12ppm / ℃, Knoop hardness of about 470-500 and elastic modulus of 6 × 10 ⁶ psi. In addition, the product has a characteristic of smoothly cutting along the curved plane and not birefringence under extreme light.

It is composed of the same material as the above product, but the products of Examples 4 and 5 ° C. have almost unlimited size and number of pores contained therein. Of course, due to the pores formed in the product it is natural that physical properties such as compressive strength, tensile strength, modulus and hardness change.

Example 12

A composition suitable as a tooth cement and a tooth filler was prepared as follows.

A. Share 2.0 g of hydroxyapatite ceramic ground in a solution of 20 mg of N-phenylglycine and glycidyl methacrylate condensation product (trade name NPG-GMA) in 7 ml of ethanol.

After kneading for 5 minutes, ethanol was evaporated under reduced pressure at room temperature and the remaining solid residue was dried at 1 mmHg for 2 hours.

B. Mix 80 mg of a sample of this substance with 30 mg of a mixture of 0.4 mg of benzoyl peroxide, hydroxy ethyl methacrylate: bisphenol A and glycidyl methacrylate (1: 2). The mixture thus prepared is placed in a cylindrical iron mold and cured for 3-5 minutes. The compressive strength of the material thus produced is 24350 psi.

Example 13

60 parts powdered hydroxylapatite ceramic, 13 parts hydroxyethyl methacrylate, 27 parts condensation product of bisphenol A and glycidyl methacrylate N, N-bis- (2-hydroxyethyl) -P-toluidine Uniform mixing of 0.3 parts and 0.8 parts of benzoyl peroxide yields a resilient free-flowing composition useful as a dental pit and rupture sealant. The mixture is cured for 3 minutes in the cylindrical iron mold. The average compressive strength of this material is 20,400 psi.

Example 14

A method for preparing a composition useful as a dental filler is as follows.

HL-72)으로 구성된 혼합물 40mg을 주가한다. 상기 혼합물을 잘 반죽하여 원통형 철형에 넣고 4시간동안 방치한다. 철형뚜껑을 제거하고 시편 3개를 시험하였더니 평균 압축강도가 22,300psi이었다.0.5 g of powdered hydroxyl apatite ceramic is added to 5 ml of 2-propanol. 2-propanol is evaporated under reduced pressure at room temperature to remove hydrated water on the ceramic surface. 120 mg of benzoyl peroxide was added to 120 mg of the hydroxyapatite powder thus treated, and then a condensation product of bisphenol A and glycidyl methacrylate, triethylene glycol dimethacrylate, and N, N-bis- (2-hydroxy Ethyl) -P-toluidine (epoxylite

40 mg of a mixture consisting of HL-72) is added. The mixture is kneaded well and placed in a cylindrical iron mold and left for 4 hours. Three specimens were tested with the iron cap removed. The average compressive strength was 22,300 psi.

Example 15

Into a solution of 30 mg of a condensation product of N-phenylglycine and glycidyl methacrylate in 7 ml of ethanol, 1 g of hydroxyapatite ceramic powder is vortexed dropwise. Ethanol is evaporated under reduced pressure at room temperature. To this mixture, 180 mg of a mixture consisting of 180 mg of hydroxyl-apatite ceramic powder and 3.0 mg of benzoyl peroxide is added to a mixture of 60 parts of a condensation product of bisphenol A and glycidyl methacrylate and 40 parts of triethylene glycol dimethyl acrylate. The resulting condensation is kneaded well and placed in a cylindrical iron mold and left for 3 hours. Four specimens were tested with the iron cap removed. The average compressive strength was 22,300 psi.

Example 16

의 상품명으로 시판되는 ESPE. G.m.b.H로 사용할 수 있는 액체와 고체성분의 폴리칼복실레이트세멘트를 40% 폴리아크릴산과 아연화로 부터 만들었다.100 mg of hydroxyl-apatite ceramic powder, 300 mg of zinc and 300% of 40% polyacrylic acid were mixed together to prepare a composition for use as a dental cement, an orthopedic cement or a temporary dental filler. The mixture thus prepared is placed in a cylindrical iron mold and cured for 3-5 minutes. The lid was removed from the cast iron and four specimens were tested. The average compressive strength was 12,400 psi. The average tensile strength of another five specimens was 1630 psi. Dureto in West Germany

ESPE marketed under the trade name of. Liquid and solid polycarboxylate cements for use with the GmbH were made from 40% polyacrylic acid and zinc.

Example 17

의 상품명으로 시판되는 ESPE G.m.b.H로 사용되는 액체와 고체성분의 폴리칼복실레이트 세멘트는 40% 폴리아크릴산과 아연화로 부터 제조하였다.6 parts by weight of 40% polyacrylic acid, 6 parts by weight of hydroxyapatite ceramic powder and 4 parts by weight of zinc were mixed together to prepare a composition that can be used as a tooth cement and a tooth filler. The curing time of the thus prepared composition is 5-10 minutes. Dureto in West Germany

Polycarboxylate cements of liquid and solid components used under the trade name of ESPE GmbH were prepared from 40% polyacrylic acid and zinc.

Example 18

The following is an example of a tooth filler composition.

Component Weight Percent

Styrene-modified repolyester resin (glydene Glide pole G-136) 29.2

Benzoyl Peroxide 0.7

Styrene 0.6

Methacryloxypropyltrimethoxysilane 1.5

Hydroxyapatite Ceramic 68.0

Example 19

The following are examples of compositions useful as dental cement, buccal and pulp capping agents.

Component Weight Percent

Epoxy Resin (Union Carbide 2774) 67

N-3-oxo-1,1-dimethylbutylacrylamide 23

Hydroxyapatite Ceramic 10

Example 20

The following is an example of a composition suitable for the production of dentures and teeth.

A mixture of 60 parts by weight of 150-200 mesh hydroxylapatite ceramic and 40 parts by weight of polymethylmethacrylate powder is mixed with 15 parts by weight of methylmethacrylate liquid monomer, and the mixture no longer adheres to the vessel wall and is viscous. Leave in sealed container at room temperature until disappear. The material is then placed in a suitable mold and the mold and contents are impregnated with water, heated for 1 hour and held at this temperature for 30 minutes. The mold was air cooled for 15 minutes and then cooled with tap water.

Bio-adaptability of the hydroxylapatite ceramics of the present invention was confirmed by transplantation experiments. When the ceramic fragments prepared by the method of Example 1 were implanted into the rat peritoneum or subcutaneously inserted into rabbits, there was no symptom. There was no absorption of the ceramic even after 28 days.

The phenyl of the hydroxyl apatite ceramics prepared by the method of Example 3 was orthopedic transplanted to the thigh of the dog. Implants were followed in vivo by periodic X-rays. One month and six months later, the animals were killed and the femoral sections containing the implants were dissected. The thighs were made multiple incisions around the implant and examined by optical and scanning light microscopy. Both implants at 1 and 6 months had a normal therapeutic effect, and the new bone was strongly bonded to the graft surface without destroying the fibrous tissue. There was no inflammation or other physical reactions and no absorption of the implant.

Claims (1)

Translucent isotropic, polycrystalline, sintered, characterized in that the average crystal size ranges from about 0.2 to 3 microns, the density is from about 3.10 to 3.14 g / cm 3, and is substantially hydroxyl-free apatite with cleavage along a smooth, smooth surface Prosthetic material composition comprising the treated ceramic as an essential component.