DE2641695C2 - Implant of A1 2 0 3 material and method of making the same - Google Patents

Description

The invention relates to an implant made of rial, the use of this implant and a method to manufacture this implant. This implant is for dental surgery or as an implant for that orthopedic surgery can be used.

So far, metal (for example stainless steel, cobalt-chromium alloy etc.) has often been used as a material for Implants used, but it must be said in general that an implant made of a metal, in many cases with regard to its so-called "kinship" to surrounding tissue (such as for example its ability to adhere to the tissue, its Wettability by the tissue) is inferior, and in addition there is the possibility that the implant has a tendency, through salivary fluid, to be secreted of the mouth, food, body fluids, blood and the like to become ionized and thereby have adverse effects a of metallic ions on the human body. So it is in the case of stainless Steel, most commonly used as an implant for orthopedic Surgery used is necessary to perform repeated surgery to the implant to be removed from the body for a certain period of time after the operation.

In addition, as DE-PS 5 83 589 shows, from which the preamble of claim 1 is

t5 goes, already in the thirties, implants made of pure, crystallized aluminum oxide, shaped and sintered according to the principle of ceramic manufacture, Proven to be advantageous in that the strength and hardness of the pure, crystallized material Aluminum oxide, which is processed in a known shaping and subsequent sintering process, is larger than those of the previously used materials gold, platinum, porcelain, rubber and condensation or polymerisation plastics is and therefore gives the possibility of spare parts of any kind for human Or animal bodies o. The like. To produce, while the The stresses and strains used beforehand for implants ie the materials used were not able to cope with many repairs, which are uncomfortable for the patient.

3ü became necessary.

Recently, however, as described in DE-OS 25 40 077, implants have proven to be advantageous, which do not consist of pure aluminum oxide material, but a certain, not inconsiderable one Percentage of other compounds included, and which are also based on the principles of ceramic manufacture shaped and sintered. These ceramic materials are used because of their better tissue compatibility preferred over metals, it being pointed out in DE-OS 24 40 077 that Aluminum oxide ceramics, which in the final fired state 95 to 50% by weight of Al2O3 and 5 to 50% by weight of one or contains several of the compounds ZrO2, La2Ü and Y2OJ, in particular, it is stated that the ceramic material is preferably in the completely fired state 90 to 80% AI2O3 and 10 to 20% of at least one, but preferably from two of the compounds ZrO2, La2O and Y2O3 should contain.

5,) In the case of an implant made of polycrystalline ceramic It is true that the implant is good in its relationship with regard to the tissue by which it is surrounded and that it is still extremely chemically stable, so that there is no need for the implant to remove from the implantation area after surgery, but such an implant in particular has the disadvantage that it is inferior in its mechanical strength compared to a metallic implant is. In view of this fact, the patentee has made various inventions for improvement the mechanical strength of a ceramic implant submitted. The post-operative strength of a such an implant largely depends on its structure. For example, it resulted in the implant according to DE-OS 25 40 077 such a structural meaning insofar as a tightening force that is created by attachment a nut by means of a thread from the upper end of a screw-like implant pin made of ceramic

mik, which was embedded in the bone tissue (and if necessary by threading the nut over the lower part of the pin, which passes through the bone tissue protrudes through), was used to attach the implant pin to the bone tissue in such a way that that the implant post could withstand external forces, such as repeated bite strokes exerted on the post after implantation. In In a similar way, in the case of the implant that is described in DE-OS 26 15 116, the structural point of view taken into account in such a way that a screw-like implant pin made of ceramic on the circumference has been provided with a horizontal flange that acts as a stabilizing seat by keeping the flange tight or tightly inserted into a counterbore formed in a cortical bone (hard tissue) was in the state of the pen in which it threaded into the bone so that the pin can withstand the external force in this way that later came into play.

Finally, from the magazine “Arch, orthop. Accident Chir. " S3 (1975), pages 269 to 278 in an article on »Requirements for oxide ceramic materials as biomaterial for artificial joints «by E. Dörre, H. Bentier and D. Geduldig as well as in the "DECHEMA material table" DWT material group 66, December 1963, Sheets 1 to 3 known that polishing polycrystalline aluminum oxide ceramics by diamond grinders will. In the case of polycrystalline aluminum oxiri ceramics, the surface can, to a certain extent, be smoothed, but in any case sharp edges and scratches remain, which are caused by the polishing can be generated, and these sharp edges and scrapes make it useful compared to the surrounding tissue (as can be seen from observations in the submicron range) is reduced a relatively unfavorable applicability of such a ceramic for implants. With regard to the polycrystalline Alumina ceramics has also been shown to be effective when subjected to fire polishing and / or Immersion in molten salt treats the grain boundaries of the ceramic by the heat and / or the molten salt is adversely affected in such a way that many cavities are created, as a result, the flexural strength is reduced.

The object of the invention is to provide an implant made of AbOs material which, with regard to on its crystalline structure in its mechanical strength, flexibility and relationship to the tissue (especially osteoplastic cells) is more excellent than polycrystalline Ceramic made from a wide variety of ceramic materials.

According to the invention, this object is achieved in that the implant consists of a single crystal sapphire ceramic / k element and has a smooth, polished surface.

In addition, the invention provides a method for producing and using this implant, as specified in the claims in detail, made available.

In general, polycrystalline ceramics, for example a sample of polycrystalline alumina ceramics (a rod-shaped sample of 3 mm in diameter, which will be discussed in more detail below), exhibits a flexural strength of only 2500 to 3500 kg / cm ² because of its internal Micro-structure that allows impurities (binders, grain growth retarders, etc.) to be present in the crystal grain boundary, whereas a sample of single crystal sapphire ceramic has no such crystal grain boundary and consists of a complete single crystal structure, with the result that the latter This type of ceramic has flexural strengths of the order of 10,000 kg / cm ² and is also by far superior to polycrystalline ceramic materials in its flexibility.In addition, in the case of polycrystalline ceramic, the presence of fine voids in the crystal grain boundary prevents the ceramic materials from being related to the se surrounding tissue and has a tendency to lower the adhesiveness of the ceramic materials to the surrounding tissue, whereas single crystal ceramic materials are excellent in particular in their affinity to surrounding tissue because they do not contain such crystal grain boundaries which inhibit kinship. In this connection it should be pointed out, which will be discussed in more detail later: the single crystal sapphire ceramic in rod-like, columnar, plate-like or similar form of single crystal can be obtained from Λ-ΑΙ2Ο3, and if the ceramic is for an implant is used, then it is cut and machined into the desired shape by means of a diamond grinding tool or the like, such as is suitable for a part of dental or orthopedic surgery for a broken bone, and such suitable shapes are e.g. B. a screw-like endosseous implant part, a plate-like endosseous implant part, a pin-like endosseous implant part and a pressure plate, with sharp end edges are formed on the outside of the implant as a result, and at the same time remain in a similar manner sharp, wave-like scars or scratches from the cutting and processing on the machined surface. It is a theoretically secured fact that these angular parts not only reduce the relationship of the implant to the bone tissue around the parts, but that these parts, if they remain implanted in the bone tissue for a long time, form causes for the development of bone ulcers or - cancer because of the stress that the angular parts repeatedly exert on the bone tissue. In addition, the presence of scars formed by the cutting and shaping enables new bone tissue to multiply partially in the angular parts alone and become a cause of the inhibition of the growth of a uniform bone tissue. In addition to such concerns and disadvantages arising from a medical perspective alone, the presence of the scars or v /. Scratches a stress or stress concentration in the area provided with scars or scratches in the case of such a homogeneous body like a single crystal, so that in this way a rapid reduction in the strength of the implant to a strength level of about 5000 kg / cm ^{2 is} effected. Accordingly, in accordance with the invention, the angular ends are rounded to a smooth surface to eliminate the possibility of ulcers and cancer and to cause uniform development of bone tissue by removing the scars that have remained on the machined surface of the implant , by means of

high temperature chemical polishing with molten salt or high temperature fire polishing with Hydrogen can be removed after processing the implant, and this further reduces the flexural strength, which is inherent in the single crystal. restored or created greater strength than this.

The implant according to the invention and the method for producing this implant, the surface condition of the implant at its manufacturing stage and the flexural strength of the implant are shown below on the basis of some preferred exemplary embodiments of the invention with reference to FIGS. 1 to 8 of the Drawings explained in more detail; it shows

F i g. 1 to 3 longitudinal sectional views of in each case an implant according to the invention, which is in a dental implant is used;

F i g. 4a and 4b show the case in which an implant according to the invention for treating a broken bone is used, where F i g. 4a is a perspective view of a pressure plate and FIG. 4b is a longitudinal sectional view which shows the condition of the pressure plate when attached to the broken bone is; and

Fi g. 4 to 8 photomicrographs of the surface condition a single crystal sapphire ceramic element in different states or processing stages of this Elements.

(I) Method of producing a single crystal sapphire material

A -AbCh material was melted in the crucible by high frequency induction heating, and a single crystal sapphire seed was immersed in the melted material. When the seed was lifted from the molten material, a single crystal solid of Λ-Αί ₂ θ3 in the shape of a rod was obtained from the latter by surface tension of the molten material. This process is known per se as the Czochralski process, but the use of an apparatus for continuously forming a single crystal called the "E ^ G process" which is an improvement over the Czochralski process is industrially advantageous. According to this EFG process, a mold which is excellent in wettability with respect to a molten material is immersed in a molten material, and the seed is lifted from the molten material through the mold, with the result that a solidified single crystal mass of a desired cross-sectional configuration can be obtained, e.g. B. with a rod-shaped, a plate-shaped, a tubular or similar configuration. For example, the surface condition of a rod-shaped single crystal material having a diameter of 3 mm which was raised at a rate of 20 mm / min from the material which was melted at a temperature of 2050 ° C. in an argon atmosphere according to the EFG process , smooth, but an uneven layer is dispersed, and this single crystal material had a flexural strength on the order of 8,000 to 10,000 kg / cm ² .

(H) Cutting and editing the somatic element

A single crystal material was cut and shaped into an implant of a desired configuration by means of a diamond grinding tool. For example, the exterior of the single crystal material shown in section (I), which was cut by a machine with a No. 250 diamond grinding tool, had very sharp edges, and the surface of the material was rough because of the presence of the cutting scars and the bending strength of the material was on the order of 6000 kg / cm ² .

ίο (III) Removal of cutting scratches or scars

As has been described, sharp-edged and dipping wave-like cutting scars or scrapes remain (For the term »scar or scratch«, the term »scratch« is used in the following) on the surface of the single crystal implant after cutting and processing, and the scratches are removed so that the sharp edges are rounded and a smooth surface results and the flexural strength of the implant is restored and improved, namely in the explained below.

(IM) -A. High temperature fire polishing with water-based cloth

After cutting and processing, a single crystal material was subjected to high-temperature fire polishing with hydrogen at 1200 to 1900 ^° C., preferably at 1500 to 1700 ^° C., so that the sharp edges were rounded off and the surface of the material smoothed. For example, the single crystal material after cutting and processing was subjected to high-temperature polishing at a temperature of 1550 ° C. for 20 minutes in an atmosphere of reducing gas (H2). The sharp edges had been removed from the surface of the material so treated, and this surface was far smoother than that of the material which had been cut and worked, but certain irregularities still remained in the surface. The flexural strength of this material had been restored ^{to about 9,000-10,000 kg / cm 2.} In addition, it should be noted that when the temperature is lower than 1200 ° C, surface polishing is not carried out in a satisfactory manner, and when the temperature is higher than 1900 ⁰ C, the surface polishing is carried out so vigorously that deformation of the molded Body itself begins on the single crystal surface and the body changes its configuration markedly so that it becomes unsuitable for use. The temperature is preferably 1500 to 1700 ^° C.

(IH) -B. High temperature chemical polishing with molten salt

When the single crystal material after cutting and working was immersed in molten salt selected from one of the following salts: borate, molybdate (Na2Mo207, Li M02O7, PbMoO ₄ etc), tungstate (Na ₂ W ₂ O ₇ , Li ₂ W ₂ O ₇ , PbWO ₄ etc.) and vanadium pentoxide (V ₂ O ₅ ) then it can be easily melted as the larger cutting scratches form the larger reaction surface area and the entire surface sews into a smooth shape. For example, single crystal material was cut and worked into a

IO

dipped molten salt of borax at 1100 ° C for about 10 minutes and subjected to high-temperature chemical polishing with molten salt. The material treated in this way has a more regular surface than a material that has been subjected to high-temperature fire polishing with hydrogen, but fine irregularities still remain on the surface. The flexural strength of the material thus treated was restored and improved to a value of 10,000 to 12,000 kg / cm ^2. If a molten salt of molybdate is used in place of that of borate, then the material can be immersed in the molten salt at 1200 ° C for about 20 minutes, and if a molten salt of vanadium pentoxide is used then the material can be immersed at 1400 ° C immersed in the molten salt for about 10 minutes with the same results. Similarly, a molten salt of any of the following compounds can be used; Tungstate, lead oxide, and sodium or potassium carbonate.

(Ul) -C. Combined application of high temperature chemical polishing with molten salt and of high temperature fire polishing with hydrogen

For example, the single crystal material after cutting and processing was first subjected to high temperature chemical polishing with molten salt under the same conditions as those in Section (HI) -B. and then it was subjected to high-temperature fire polishing with hydrogen under the same conditions as those in the section (HI) -A. are described. The surface state of the material treated in this way was approximately that of the single crystal material which had been taken out of the treated salt, but it is much more homogeneous and no irregularities were noticed at all. Furthermore, the flexural strength of the material was improved to a value of 15,000 to 20,000 kg / cm ^2. This strength is higher than the strength inherent in the single crystal after it is pulled out of the molten salt. and it should be noted in this connection that the flexural strength of stainless steel is 10,000 to 12,000 kg / cm ² .

As explained above, when the material can be subjected to a high temperature chemical polishing with molten salt and / or a high temperature fire polishing exposed to hydrogen, not only removes the sharp end edges of an implant but the surface of the implant can be smoothed, and also the flexural strength can be increased of the implant can be improved through a very simple process. That way is the inventive method by far more advantageous industrially than mechanical grinding, the one gradually reducing the grain size of the grindstone in order to obtain a smooth surface.

In order to further explain the invention, the figures in the drawing will now be discussed in greater detail be, the F i g. 1 to 4 embodiments of Show implants according to the invention, which are used for dental implantation, as well as = outside it an orthopedic surgical implant to treat a broken bone.

example 1

A columnar single crystal sapphire material obtained by the EFG process of the section (I) was cut and processed by the method described in the section (II), and it was then treated for the purpose of removing the cutting scratches by the method, that in section (HI) -C. using a borate polishing bath. By the treatment carried out in this way, a screw-like endosseous implant part provided with a flange was obtained, as shown in FIG. 1 where there is a smooth surface all over the part. The endosseous implant egg! / Ί was formed on the periphery of its main body 1 so that it could be inserted into a jawbone b with threads 10 which can be screwed into a stitch or Gewiridcioch 5 formed in the jawbone b . The head 2 of the enossal implant part i is a part that serves as a receiving part for a drive tool (not shown) when the part is to be screwed into the needle hole, and the head 2 also serves as a part over which an artificial tooth / placed or is attached, namely by an adhesive or adhesive filler material 4. The head 2 has been formed as a hexagonal column by machining. In addition, a disk-shaped horizontal flange 3 is at the peripheral boundary between the main body 1 and the head 2, and this horizontal flange 3 is adapted to be tightly inserted into a counterbore 6 which has been formed in the upper hard tissue b \ This insertion can be made in the state of the endosseous implant part b \ in which the latter is screwed into the bone, and this flange continues to serve as a stabilizing seat. It should be noted that in FIG. 1 with / "denotes a mucous membrane of the gums (the same applies to FIGS. 2 and 3); bi is a soft tissue of the bone and fr» is a hard tissue beneath the soft tissue (the same also applies to FIG. 2 , 3 and 4b).

The flanged endosseous implant part / Ί is structurally improved in its mechanical strength so that it can withstand repeated external forces, which result from bite impacts, can withstand, and in addition, the endosseous implant part / ι, there it is made of single crystal sapphire material, much higher mechanical strength than a polycrystalline one Ceramic implant post of the same shape and size. Even the main body 1, the one Has a diameter of 3 mm, can withstand such repeated external forces sufficiently, whereas there was a possibility that a polycrystalline ceramic implant post was broken what depends on the tension or load acting on it X-ray observations, performed 6 months after the operation showed that no part of the endosseous implant part / Ί was broken and that the endosseous implant part also had made no movement, but that the tissue around the endosseous implant part A had completely grown back and that the endosseous implant part is an excellent relationship to the Tissue had and that furthermore no formation of a bone tissue due to breakage or crumbling caused pocket had taken place.

Example 2

A columnar, screw-like endosseous implant part / 2 which has a smooth surface, as shown in FIG. 2 was obtained by cutting and working a single crystal sapphire material and removing the scuffs formed on the surface of the material by cutting and working from the surface of the endosseous implant part in the manner described in Example 1. FIG. The obtained endosseous implant part / 2 is provided with a continuous thread, and the lower part of the thread is used as a thread engaging part 11 adapted to be implanted in a tapped hole 5 formed in the jawbone b which is associated with the main body 1, and the upper part of the thread is used as a threaded connection part 12 on which a nut η can be screwed, on the exposed part above the upper surface of the jawbone b, and finally the head 2 of the thread, which is machined to form a hexagonal column, used as a part on which a screw drive tool can engage. The nut η is made of polycrystalline aluminum oxide ceramic. The nut η is threadedly engaged on the threaded portion 12 of the main body 1 such that the bottom of the nut comes into close contact with the bottom of the counterbore 6 formed on the upper surface of the hard tissue b \ above the jawbone b . Furthermore, an artificial tooth t is placed over the nut η , to be precise by means of an adhesive or adhesive filling material 4, so that the prosthesis-fitting operation is completed in this way.

Since the endosseous implant member / 2 described above is structurally adapted to be fixed to the jawbone b by screw tightening force of the nut η , it can sufficiently withstand the external forces generated by bite impacts, in addition to this the endosseous implant part h because it is made of a single crystal sapphire material produce the same effect and the same effect as the endosseous implant part in Example 1.

Example 3

A plate-shaped single crystal sapphire material obtained by the EFG process explained in the section (I) was cut and processed according to the process described in the section (II), and then the scuffs formed by the cutting and processing were made were, by the in section (HI) -B. was removed using a molybdate bath to obtain a sheet-like endosal implant part / 3 which was smooth over its entire surface as shown in FIG the mucous membrane / the gums were pushed through and this main body 1 was embedded in the jawbone b , an artificial tooth t being attached over a sprout-shaped head 2 or on this head.

According to radiographic observations carried out 6 months after performing the operation wuden, was the tissue around the endosseous part of the implant / 3 well grown or overgrown, and no movement of the endosseous implant part / j was detectable, and much less any fracture of the endosseous part.

Example 4

A curved, plate-shaped single crystal sapphire material produced by the EFG process as described in Section (I) has been described, has been obtained, has been

! 0 was cut and shaped, and the scuffs formed on the surface of the material by the cutting and shaping were cut off by the one in the section (IH) -A. was removed so that a pressure plate U for orthopedic treatment of a broken bone was obtained, the pressure plate / 4 being smooth over its entire surface and having pin through holes 7 as shown in Fig. 4a. On the other hand, as shown in FIG. 4b shows a screw-like endosseous implant part / ₅ formed (or several of these endosseous implant parts were formed) which had an external thread 10 which had been formed on a main body and which also had an engaging part for receiving or engaging of a driving tool for a hexagonal columnar part at its head 2, and this engaging part was obtained in the same manner as the endosal implant part / 1 in Example 1. The pressure plate / 4 was broken on the periphery of one Arm bone b is attached in the state of the broken part of the arm bone in which this was arranged end-to-end (with the smallest possible gap between both ends), and the pressure plate was attached to the periphery by the pin screw-like endoscope parts / 5, and by screwing them into puncture or threaded holes that had been formed in the arm bone b . According to radiographic observations made 6 months after the operation was performed, a bone tissue was gradually re-grown in the gap in the broken part. This shows that the pressure plate / 4 is attached quite naturally to the arm bone b despite the violent movement made by the arm bone. In addition, according to radiographic observations made one year after the operation, there was no sign that the bone in the bone tissue near the pressure plate / 4 and the pin screw-like endosseous implant part / 5 was weakened or crumbled, and no trace was found a fracture of an endosseous implant part / 5.

As can be seen from the description and the examples described and illustrated above can, due to the invention, such characteristic properties as mechanical strength, inherent to the single crystal, excellent flexibility and kinship to it the surrounding tissue in full use by using single crystal sapphire ceramic in the invention is used as a material for an implant, which is formed into a desired configuration and on its entire surface is subjected to a finishing treatment that gives it a smooth surface, namely in that the sharp edges and the scratches caused by cutting on the Surface of the material to be removed. Accordingly, the implant according to the invention can even then

11th

if it is made very small, e.g. B. with a Diameter of 3 mm, which was previously impossible with polycrystalline ceramics, withstand external forces sufficiently, so that it has become possible to limit the area and formation of an implant part to be reduced to this level.

The jawbone also gives way when eating hard foods, and when moving an arm the arm bone also gives way. But there the implant according to the invention has excellent flexibility, there is also a print of the type described in FIG Responding to such yielding of the jawbone and arm bone, which results in that the implant is less prone to breakage. Furthermore, the implant according to the invention has no risk of The development of bone ulcers or bone cancer, but it is the new growth or Regrowth of a surrounding tissue positive or inevitably beneficial because that used in the implant Material is ceramic, and because the implant has no sharp end "<antennas and beyond on the Surface is smooth. Finally, the implant is also toxicity-free and, as a result, requires not the possibility of such a removal of an implant part by re-operation, as is the case in the case of an implant made of metal.

The following are the photomicrographs shown in FIGS. 4 to 8 explained in more detail:

Fig. 4 is a photomicrograph in thousands Magnification showing the surface condition of a single crystal sapphire ceramic element after the Element has been pulled from the crucible. The F i g. 5 shows one of the FIGS. 4 similar or similar Photography, but in the condition of the element that results after it has been cut and processed. F i g. 6 is one of the F i g. 5 similar or similar photograph, but it was taken after the Element had been subjected to high temperature chemical polishing with molten salt. Finally, FIG. 7 is a similar or similar to FIG. similar photography. however, it was added after the element was subjected to high temperature fire polishing had been exposed to hydrogen. Finally, FIG. 8 shows a similar or similar to FIG. Similar photograph, but with the element initially subjected to high temperature chemical polishing and then subjected to high temperature fire polishing.

For this purpose 4 sheets of drawings like this

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Claims (10)

Patent claims: 1. implant made of Al ^ Oa material, characterized in that it consists of a single crystal sapphire ceramic element (i \, / ?, / 3, / 4, / 5) and has a smooth, polished surface 2. Use of the implant according to claim 1 as a screw-like endosseous implant part (i \, ij) in dental surgery. 3. Use of the implant according to claim 1 as a sheet-like or plate-like endosseous implant part in of dental surgery. 4. Use of the implant according to claim 1 as a pin-like endosseous implant part (/ 3) in dental surgery. 5. Use of the implant according to claim 1 as a pressure plate (U) in orthopedic surgery. 6. A method for producing an implant according to any one of claims 1 to 5, characterized in that 4ass from the single crystal sapphire ceramic element a desired implant configuration by cutting out and processing the surface and then the surface by high temperature chemical polishing with molten Salt is processed. 7. A method for producing an implant according to any one of claims 1 to 5, characterized in that that from the single crystal sapphire ceramic element by cutting out and processing the Surface a desired implant configuration is formed and then the surface through High temperature fire polishing is processed. 8. The method according to claim 6, characterized in that the molten r salt by immersion comprises the shaped single crystal sapphire ceramic element (i \, / 2, / 3, / 4, / 5) and the salt of borate, molybdate, tungstate , Vanadium pentioxide, lead oxide, and sodium or potassium carbonate. 9. The method according to claim 7, characterized in that the high-temperature fire polishing at 1200 to 1900 ⁰ C, preferably at 1500 to 1700 ⁰ C, is carried out in a reducing gas atmosphere. 10. A method for producing an implant according to any one of claims 1 to 5, characterized in that a desired implant from the single crystal sapphire ceramic element (i \, h. / 3, '4, / 5) by cutting out and processing the surface Configuration, after which the surface is processed by high temperature chemical polishing with molten salt and then by high temperature fire polishing.