FI91595B - Granule implant which can be implanted in living tissue - Google Patents

Description

91595

GRANULAR IMPLANT IMPLANTED IN LIVING TISSUE

The invention relates to a granular implant implantable in living tissue, wherein at least one component of the granular material is a mixture of Ca-P glass resorbable into tissue, such as bone, soft tissue or biomass, and to which at least one non-resorbable component can be added to the granular material. a mixture of bio or Ca-P glass.

The first experiments on artificial materials implanted in tissues were not made until the late 19th century, although the subject has always been of interest to 10 researchers. However, they did not lead to results. There is mixed success instead. Since the 1950s, produced the placement of various titanium and tantalum metal plates inside a bone, e.g., the jaw.

The extensive subperiosteal structures and extensive intraosseous plates used in said oral implants are being omitted due to inflammation and surgical difficulties. It has been replaced by individual screws (Bränemark, Straumann, Bioceram; ref.1 Albrektoson et al .: Special Reprint. The long-term efficacy of currently used dental im- • 20 plants. A Review and Proposed Criteria of Success. Int. J.

Oral & Max. Fac. Implants 1. 1986) and conical large cylinders resembling a single tooth root (Fria-lit; ref.l). What current methods have in common is that the structure is implanted inside the jawbone. Thus, mechanical contact is obtained between the implant-25. From the implants, a protrusion extends through the mucosa into the oral cavity. This protrusion acts as a support for the prosthesis. The surface epithelium of the mucosa should adhere to the surface of the protrusion to prevent bacteria from entering the bone. Good cleaning of the area is always a prerequisite.

30 The method of attachment in said methods has often been inflammatory tissue between the bone and the implant. This can be removed by a 2-step cut, in which the fastener is fixed in the first step by screwing it completely inside the bone (ad Modum Bränemark, ref.1). In the next step, after 3 to 6 months, a second incision is made, in which an extension extending into the mouth is installed. The results have been satisfactory.

The method has generated several variations (IK implant, IMZ implants, Core vent implants). The materials used are titanium or CoCr alloy with a Ti surface 10 plasma sprayed (TiO 2). The healing time is 3 to 6 months, although the manufacturer promises that the implant can be stressed immediately after surgery. The main disadvantage is the inconvenience and complexity of the method.

The simpler is the Straumann method, in which the fixed extension of the 15-hole cylinder comes directly into the mouth and the implant is installed in a single operation. The material is a CoCr alloy with a plasma sprayed TiO2 surface. Due to uncertain results, the cylinders are being taken out of service.

The third type of implant currently in use is the polycrystalline Frialit implant made of Al 2 O 3 ceramics, which is installed immediately after tooth extraction in an enlarged • extraction well. In shape, this implant tapers and is massively tapered to the tip. Due to the fragility of the ceramic structure, these implants can only be used to support a single tooth at a site of the mouth subject to relatively little bite stress, such as the anterior teeth.

The types of materials used can be grouped as follows: 1. Inert materials that do not react with tissue 30 but grow very close to bone: Al 2 O 3 ceramics, Ta and Ti metal and their alloys (TiV4A16), carbon in various forms, Teflon.

Il 3 91595 2. Bioactive materials that actively and rapidly adhere to bone, i.e. are surface reactive and induce bone growth: Hydroxyapatite, Ca-P glass and Ca-P glass ceramics, "bioglasses". Tricalcium phosphate or TCP 5 (resorbed). The material composition and method of manufacture of these affect resorption, which ranges from completely unabsorbed to resorbable.

The current situation for bioactive materials is as follows: 10 1. The incorporation of hydroxylapatite (HA) into the metal is problematic. Attempts have been made to mechanical joints (De Putter,

De Groot), which is difficult due to the fragility of HA and has not led to satisfactory results.

Plasma spraying has also been attempted; however, the preservation of the crystal-15 structure has not been demonstrated and the surface decomposes into easily resorbable TCP, so the binding is not long-lasting (World High Tec. Congress, Milan 1986). Coral-based HA has also not been a better solution than synthetics. However, HA is a preferred substance to which the collagen fibers of 20 tissues adhere and are highly calcified (Jarcho et al. In several studies; ref.2 De Putter, De Lange, De Groot: Permucosal · · dental Implants of dense hydroxylapatite. Fixation in alveolar bone; Abstract: Int. Congress on tissue integration in oral and maxillofacial reconstruction, Brussels 1985).

2. CaP glasses and CaP glass ceramics, i.e. the so-called bioactive glasses have been found to be very "ossifying" in several studies (Hencke et al. since 1971; ref.3 Gross et Strung: The 30 interfaces of various glasses and glass ceramics with a bony implantation bed. J. Biomed. Mat.Res. 251-271: 19, 1985). The reaction is based on gelation of the SiO 2 surface and enrichment of Ca and P. In this case, Ca and P crystallize as HA in the collagen fibers adhering to the surface.

91595 4

A good method should meet the following ideal requirement:

The implant must have a surface adhering to the bone and mucosa and have a bone-promoting effect.

Such surfaces are: HA = hydroxyapatite TCP = tricalcium phosphate Bioactive glass or glass-ceramic 10 Implants today exist with the required strength to achieve a small size and strength A metal core surrounded by a strongly adhering bio-or Ca-P-resorbable metal oxide. In addition, the outermost is Ca-P glass resorbable into bone 15 or biomass (ref. U.S. Pat. 4497629 Ogino et al.). Thus, requirements 1 and 2 become seemingly fulfilled, but after the outer layer is resorbed away, the adhesion of the inner layer to the tissue is not satisfactory.

Adhesion in implants has been improved by the use of hydroxyapatite, or HA. In addition to various implants, said bioactive materials have been used to repair various bone defects in blocks and granules. The best known are HA alone, known as bioactive

25 both as a dense form of dense and as a hollow-structured porous, and TCP which is rapidly absorbed. Furthermore, bioactive glass (BioglassR) and plastic / Ca mixture (HTRr) have been used as the granule application. A common problem is that the rate of resorption cannot be adjusted.

No implant according to the invention has been described in the literature.

U.S. Patent No. 5,91595 to 4,097,935 describes a novel ceramic product containing hydroxyapatite. However, it does not describe a layer or alloy system and the ceramic material described is not a mixture of HAs and bioglass. The said 5 patents only describe the application and production method of HA.

U.S. Patent No. 4,120,730 discloses a glass material other than bioglass. The material is not layered, and therefore the reaction rate is not adjustable.

U.S. Patent No. 4,259,072 describes a method in which two separate pieces are joined together by a glass cement other than bioglass. The reaction is not controllable because there are no layers in the structure that affect the reaction.

U.S. Patent No. 4,177,524 discloses a support member having, for example, calcium hydroxylapatite on its surface. There are no layers affecting the reaction rate here.

German patent application DE 3306648 describes machinable bioactive glass ceramics comprising Al 2 O 3 as one component, which breaks down bone. No layer structure has been described.

· U.S. Patent No. 4,708,652 describes an apatite-based ceramic material for implants. However, it does not describe implants consisting of different layers.

It is an object of the present invention to obviate the above drawbacks. The invention is characterized in that both the resorbable Ca-P glass alloy component (4) and the non-resorbable bio- or Ca-P glass mixture (2) contain hydroxyl apatite or HA as an admixture to promote adhesion to tissue and other components, and that in order to control the rate of resorption of the granular implant, the granular material also includes a component (3) which is a slowly resorbable mixture of Ca-P glass and HA.

In the solution according to the invention, the stability of the adhesion of the implant is substantially improved by adding to the granular material an ingredient whose resorption rate is adjustable.

5 It has also made it possible to use the solution in non-dental implants.

Other features of the invention are set out in the claims.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: FIG

Figure 1 shows a granule according to the invention with several layers.

Figure 2 corresponds to Figure 1 and shows a second embodiment of the granule.

Figure 3 shows the structure of an implant material formed of different granules.

Fig. 4 corresponds to Fig. 3 and shows the structure of an implant material formed of granules according to a second embodiment.

Figure 5 shows an intra-osseal granule filling placed in a bone cavity.

The granule according to Figure 1 is formed of layers. The core 1 is a strong, surface-oxidizable metal part (metal-to ceramic-alloys) with a coefficient of thermal expansion of (10-15 x 25 10'6). The next layer 2 is a strong, dense and smooth mixture 2 of non-resorbable fixing biogas, Ca-P glass and HA-ceramic coated with the metal core 1, which has a lower coefficient of thermal expansion (9-14 x 10'6). A mixture of bio- or Ca-P glass and HA 3 is added to this layer, which sintered

II

7 91595 into a dense or porous almost non-resorbable layer. A sintered, resorbable and soft mixture of HAsn and bio- or Ca-P glass 4 is attached to the bone-limiting region, which activates bone growth and immediately produces 5 mechanical bone implant junctions without causing excessive pressure on the bone.

If desired, the outer surface 4 can also be glazed. The solution is thus a layer structure in which the outermost layer 4 is resorbed and the layer 2 10 sintered on the surface of the metal core 1 is non-resorbable. Thus, resorption does not proceed to the metal, as the granule may contain resorption inhibitors (e.g. metal oxides). Between these there is in this application a somewhat resorbable intermediate layer and in addition HA has been added as an alloying element to all layers 2, 3 and 4 of the Ca-P glass. The glass makes these adhesion to the metal and the layers not only good but also very permanent. In particular, it should be noted that thus HA also adheres to the metal. In many cases, however, a satisfactorily stable result is obtained even if HA is omitted from the metal-20-coated Ca-P glass layer 2 or the intermediate layer 3 formed by the mixture of Ca-P and HA is omitted.

The rate of resorption of the mixture of glass and HA can be controlled by different concentration ratios and additives (e.g. metal oxides) just like the resorption of Ca-P glass alone.

The bioglass / HA mixture surface according to the invention adheres to the cells rapidly (1-8 hours) and the ossification also takes place rapidly due to the minerals. Such a bone junction is also strong in bone with weak structure due to its bone-inducing effect. Thus, this structure can be made smaller than before. In addition, the metal adhering to the glass ceramic supports the ceramic structure if necessary. The field of application of the invention can be further expanded by using different constructions and matrix materials.

The embodiment of Figure 2 has no metal core portion.

35 In other respects, the structure is similar to Figure 1.

91595 8

When a reinforcing structure is not needed, the metal core is omitted. This is possible when using an implant, e.g. as a bone filling. The granule can also be used as fully resorbable. In this case, layer 2 is also omitted.

Figure 3 shows an embodiment of the invention in which some of the granules are non-resorbable 2, some are slowly resorbable 3 and some are rapidly resorbable 4.

Fig. 4 has a structure similar to Fig. 3, but a metal solvent 1 is placed inside the non-resorbed granules.

Figure 5 shows a granular filling 6 placed in the cavity of the bone 5. In this case, all alternatives are possible in the composition of the filling. Essentially, the process is precisely controllable by the composition of the granules.

For example, the subperiosteal and periodontal granule fillings under the periosteum are similar, but the size of the granules varies. The size classes are, for example, the following 20 - toothpick pockets, 0.1 to 1 mm as support tissue - tibia 0.5 - 5 mm - buttons and blocks 3 mm

Layered granules are not usually used on teeth.

25

II

Claims (7)

1. In living tissue implantable granule implants, wherein at least one component (4) of the granular material is a mixture of Ca-P glass resorbable in tissue, such as bone, soft tissue or biomass, and at least one component (2) is a non-resorbable mixture of bio or Ca-P glass, characterized in that both in the resorbable Ca-P-10 glass component (4) as in the non-resorbable bio or Ca-P glass mixture (2) hydroxylapatite or HA blend to promote attachment to the tissue and other constituents, and to control the granule implant rate of resorption also includes a constituent (3) which, in its composition, is a slowly resorbing mixture of Ca-P glass and HA. 2. Granule implants according to claim 1, characterized in that at least part of the granules are formed by layers. Granule implant according to claim 1 or 2, characterized in that in order to increase the strength of the implant, a metallic component (1) is included and that at least the granule containing this component is formed of layers so that the metal is covered with a non-resorbable Ca-P glass mixture (2). Granule implant according to claim 1, 2 or 3: characterized in that the granule is formed of layers, thus including at least one slowly resorbable component (3) and a resorbable component (4) applied thereto. Granule implant according to any one of claims 1-4, characterized in that the granule is formed of 91595 layers, thus including a non-resorbable core part (2), a slowly resorbable component (3) disposed around it and a superimposable resorbable component. (4). Granule implant according to any one of claims 1-3, characterized in that the granular material includes separate granules (1, 2, 3 and 4), in which there is a metal core containing non-resorbable granules (2), slowly resorbing granules (3) and resorbable granules (4). Granule implant according to any one of claims 1-6, characterized in that granules consisting of layers and / or non-layered granules are mixed in the desired ratio in the implant. li