CA2324613A1

CA2324613A1 - Dental implant

Info

Publication number: CA2324613A1
Application number: CA 2324613
Authority: CA
Inventors: Victor Eduardovich Gjunter
Original assignee: Biorthex Inc
Current assignee: Biorthex Inc
Priority date: 2000-10-26
Filing date: 2000-10-26
Publication date: 2002-04-26
Also published as: WO2002034155A1; AU2002210298A1

Abstract

A dental implant comprises a unitary member of permeable, porous TiNi alloy; the member has an endosseous body and a supporting head which is adapted to support a dental prosthesis; the unitary member is preferably substantially cylindrical and the endosseous body, in use, is seated in a bone socket at a dental site.

Description

BACKGROUND OF THE INVENTION
i) Field of the Invention The invention relates to medicine, namely to stomatology and more especially concerns a dental implant for supporting a dental prosthesis.
ii) Brief Description of Prior Art The variety of the dental implants used nowadays for the solution of various problems of oral reconstruction, which employ the remarkable advancements in modern technology and material engineering, has become so diverse that they can be categorized by their shape, material, localization, the technique of the manufacture, etc. as shown in Manual of Orthopedic Stomatology, ed. by V. N. Kopeikin, Moscow: Medicine, 1993, p.419.
A first known device includes a cylindrical dental implant as described in Endosseous Dental Prosthesis, The USSR Copyright No. 1557709, consisting of an endosseous part, a neck and a supporting head to which a tooth prosthesis is fastened later. The core of the implant is made of solid TiNi alloy and rings made of porous and dense TiNi alloy are supported or strung on the core. Wire elements arranged in tiers are built into some rings for the reinforcement of the periodontal bonds. A device of this type is illustrated in Fig. 1.
This known device is of complicated structure; it has poor integration with the periodontium, specially in the dense pericervical area, is highly subjected to the penetration of infection into the bone socket of the implant, with such subsequent response of the organism as the proliferation and the migration of the epithelium, the formation of micro-abscesses and the development of granulation.
A second known implant also includes a cylindrical dental implant containing an endosseous part, a neck and a supporting head as described in The Application of Shape Memory Alloys in Stomatology, M. Z. Mirgazimov, V. K. Polenichkin, V. E. Gunter, V. I. Itin, Moscow: Medicine, 1991, p. 192.

The endosseous part possesses a supporting core made of dense TiNi alloy with porous coating and a supporting head on which a tooth is fastened. This device is simpler in its structure and technology compared to the known device described above and illustrated in Fig. 1.
The disadvantage of this second implant is its poor osseointegration due to the low mass of the porous material present as a coating on a solid core, and the failure of the prosthesis caused by the poor integration of the implant into the periodontium in its cervical part.
A third implant is the dental implant described in Russian Patent 2,098,043, which consists of an endosseous part, and a neck with a fastened supporting head. The endosseous part contains a supporting core made of dense TiNi alloy having a porous coating on the base and the neck. Unlike the second known device described above, the porous coating and the elaborate shape of the neck of this third device contribute to the success of the prosthesis due to the improvement of the osseointegration at the cervical part and the reduction of the bone tissue resorption. The disadvantage of this third implant is its poor osseointegration due to the low mass of the porous material forming a coating on the endosseous part.
SUMMARY OF THE INVENTION
In accordance with one aspect of the invention there is provided a dental implant comprising a unitary member comprising an endosseous body and a supporting head, said unitary member being of permeable porous TiNi alloy, said supporting head being adapted to support a dental prosthesis.
In another aspect of the invention there is provided use of a dental implant of the invention to support a dental prosthesis in a patient having need of such dental prosthesis.
In still another aspect of the invention there is provided a method of fitting a dental prosthesis in a dental site in the oral cavity of a patient comprising inserting in a bone socket at the dental site, an implant of the invention with the endosseous body innermost and the head outermost in said bone socket, and mounting a dental prosthesis on said head such that the prosthesis extends outwardly of the dental site.
In a further aspect of the invention there is provided in combination an implant of the invention, and a dental prosthesis supported on and affixed to said head.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
In a preferred embodiment of the invention there is provided a dental implant comprising a unitary member consisting of an endosseous part, a neck and a supporting head, the unitary member being of permeable porous TiNi alloy and reinforced along its length with at least one wire, preferably a single wire, made of dense TiNi alloy; preferably the implant is provided with a coating, for example, a polymer or ceramic coating, on the neck and the supporting head to prevent the infiltration of body fluids and micro-organisms.
The permeable porous TiNi alloy of the unitary member suitably has a porosity of 8 to 80%, and more especially comprises a porous body, in which the porosity extends throughout the body. In particular, the body may be formed with a controllable and variable porosity.
Preferably the porosity is at least 30% and preferably not more than 70%.
Preferably the permeability is derived from capillarity in the network of passageways which define the porosity.
The capillarity is present in the article because of the inclusion therein of a large number of pores of interconnected fine size.
Capillarity is advantageous in that it promotes migration of a desired fluid material into the network of passageways, and retention of the fluid material in the network, without the need to apply external hydraulic forces.
In general the network provides permeability and this permeability is isotropic.

The capillarity and the isotropic character are, in particular, achieved when the network defining the porosity comprises pores of different pore size, the pore size distribution being as follows:
Pore Size in Microns uanti 10-2 - 10-' 1 - 5 10-1 - 10 S - 10%

- 100 10 - 20%

100 - 400 20 - 50%

400 - 1000 10 - 50%

above 1000 remainder to 100%

In an especially preferred iment the pore size distribution embod is as follows:

Pore Size in Microns uanti 10-2-10 5-15%

10 - 400 15 - 70%

400 - 1000 10 - 70%

above 1000 remainder to 100%

The porosity of a material affects its physio-mechanical qualities, for example, mechanical durability, corrosion resistance, super-elasticity and deformational cyclo-resistivity.
The porous nickel-titanium alloy (TiNi) suitably comprises 40 to 60%, preferably 48 to 52%, by atomic weight, titanium, 40 to 60%, preferably 48 to 52%, by atomic weight, nickel, less than 2%, by atomic weight, molybdenum, less than 2%, by atomic weight, iron and minor or trace amounts of other elements, to a total of 100%. Desirably the alloy contains each of molybdenum and iron in an amount of more than 0%, by atomic weight and less than 2%, by atomic weight.

The porous nickel titanium alloy implant of the invention displays mechanical behavior very similar to that of live tissue and demonstrates high biomechanical compatibility.
The porosity and permeability of the implant of the invention are defined by a network of interconnected passageways extending throughout the unitary member. The network exhibits a permeability for fluid material effective to permit complete migration of the fluid material throughout the network, and the implant is elastically deformable.
Most suitably the permeability arises from a capillarity effect in the network and in particular a capillarity resulting from pores of different pore sizes with a defined pore size distribution in accordance with the preferred embodiments defined herein.
The network of pores renders the implant fully permeable to biological tissue thereby facilitating the osseointegration of the implant in the bone socket. After being implanted in the dental site, living tissue and bone cells grow throughout the implant and even blood circulation systems develop throughout the implant.
The implant of the invention may be used for substitution of missing individual teeth and dentitions by endosseous implantation of the prosthesis in a prepared bone socket.
The combination of all these features produces a successful technical outcome. The unitary structure of the implant facilitates its technology: that is simultaneous manufacture of all the implant structure, including the reinforcing wires by means of agglomeration. At the same time the cross-section of the implant can have any desired shape as required by the specificity of the concrete prosthesis; however, the circular shape is prompted by the technology of the operation, so the implant is preferably cylindrical.
Depending on the concrete indications and characteristics of the edentia the preferable transverse shape of the endosseous part is circular, this facilitates _7_ the manufacture and the installation of the implant with totally cylindrical shape, including its endosseous part, neck and the supporting head.
Longitudinal reinforcement along the entire length of the implant with at least one wire made of dense TiNi alloy strengthens the implant and performs the function of the solid core in the known devices. The wire, or wires, unlike the solid core of known devices, occupies less space, so there is more space for the porous material which promotes the osseointegration. At the same time, it has been demonstrated that the mechanical durability of this preferred construction is sufficient for the extended and full-value functioning of the implant.
The unitary structure of the implant means that the supporting head is present immediately after the implantation of the endosseous part, that is the first stage of the operation. In contrast known implants need to be covered with the gingival tissue for four months after the first stage of the implantation in order to prevent the penetration of infection into the bone socket through its pores. The present implant is preferably provided with a polymer coating of its supporting head and its neck, the area generally subjected to the penetration of the infection, to avoid such infection.
The invention is illustrated by reference to the accompanying drawings in which:
Fig.l shows a prior art dental implant with the wire elements extending from rings to form the periodontal bonds.
Fig.2 shows a prior art dental implant with a screw head.
Fig.3 shows a prior art dental implant with a porous coating on the neck.
Fig 4a shows a dental implant of the invention.
Fig. 4b shows the implant of Fig. 4a in a cross-section; and Fig.S is an X-ray of installed dental implants.

_g_ With particular reference to Figs. 4a and 4b, the dental implant 10 of the invention has a unitary member 1 of porous NiTi reinforced by wire 2 along its length.
Unitary member 1 has an endosseous body 12, a neck 14 and a head 16.
A polymer coating 3 extends over neck 14 and head 16.
With particular reference to Fig. 5, the implant of this invention is shown at 21, implants of the third kind referred to above are shown at 22 and implants of the invention with teeth installed are shown at 23.
EXAMPLE
The use of the implant of the present invention for the prosthesis of lost teeth is illustrated by a concrete case of the clinical use of the implant in the Clinic of Dental Implantology of Medical Material Engineering Research Institute.
Case description. Female patient R., 42 years old, diagnosed with 3d class edentia of the maxilla and the mandible according to Kennedy. Two years prior to the trial the patient had a two-stage implantation of dental implants of cylindrical shape with removable supporting head and reinforcing core (Fig.2 and Fig.S. position 22).
The control examination of the implants detected their mobility and the presence of peri-implantation sulcus resulting from the low porous mass and the deficit of the osseointegration, and also the drift of the supporting head and the reinforcing core developing during the mastication at the site of their threaded connection.
The patient underwent implantation of the implant of the invention (Fig.4 and Fig.S, position 21) with the following characteristics:
Material of member 1 - porous TiNi alloy;
The total length of implant ( 10) 17 mm;
Diameter of implant ( 10) 3.5 mm;
Material of the wire (2) - solid TiNi alloy;

Diameter of the wire (2) 0.1 mm;
The length of the coated distal part -(neck 14 and head 16) with polymer coating (3) 7 mm;
The thickness of the polymer coating (3) 0.2 mm.
The implantation was performed in the following way:
The bone socket was created under local trans-mucous anesthesia by perforating a cylindrical hole with a diameter less than the implant's diameter by 0.1 mm. The implant sterilized in an autoclave was carefully hammered into the bone socket. The gingival area adjoining the implant was dressed with Solcoseryl for 6 postoperative hours in order to protect it from the intraoral infection. A provisional plastic crown was fastened on the head of the implant in order to provide the occlusal adaptation.
In 4 months the osteosynthesis in the endosseous part of the implant was complete, and the dental prosthesis was fastened on the supporting head. The roentgenogram (Fig.S - 23) made in 4 months postoperatively demonstrates no peri-implantation sulcus, and is evidence of successful osseointegration and the guarantee of extended and effective functioning of the dental implant.

Claims

1. A dental implant comprising a unitary member comprising an endosseous body and a supporting head, said unitary member being of permeable porous TiNi alloy, said supporting head being adapted to support a dental prosthesis.

2. An implant according to claim 1, wherein said unitary member has at least one reinforcing wire of solid, non-porous TiNi extending lengthwise of said member in an interior of said member.

3. An implant according to claim 1 or 2, having a coating extending over the supporting head, adapted to prevent the infiltration of body fluids and micro-organisms.

4. An implant according to claim 1, 2 or 3, wherein said unitary member is substantially cylindrical.

5. An implant according to claim 1, 2, 3 or 4, wherein said member has a porosity of 30% to 70% and offers permeability and the porosity and permeability is defined by a network of interconnected pores extending throughout the member, in which the porosity comprises pores of different pore size, the pore size distribution being as follows:
Pore Size in Microns ~Quantity 10-2 - 10 ~~5 - 15%
- 400 ~~~15 - 70%
400 - 1000 ~~10 - 70%
above 1000 ~~remainder to 100%.

6. A dental implant consisting of a unitary, substantially cylindrical member of permeable, porous TiNi alloy, said member having an endosseous portion adapted to be seated in a bone socket of a dental site and a head adapted to support a dental prosthesis.

7. An implant according to claim 6, wherein said alloy comprises 40 to 60%, by atomic weight, titanium and 40 to 60%, by atomic weight nickel and said member has a porosity of 30% to 70% and offers permeability and the porosity and permeability as defined by a network of interconnected pores extending throughout the member, in which the porosity comprises pores of different pore size, the pore size distribution being as follows:
Pore Size in Microns Quantity 10-2 - 10 5 - 15%
- 400 15 - 70%
400 - 1000 10 - 70%
above 1000 remainder to 100%.

8. An implant according to claim 7, wherein said titanium is in an amount of 48 to 52%, by atomic weight; and said nickel is in an amount of 48 to 52%, by atomic weight.

9. In combination a dental implant as defined in any one of claims 1 to 8, and a dental prosthesis supported on and affixed to said head.

10. Use of a dental implant as defined in any one of claims 1 to 8, to support a dental prosthesis in a patient having need of such dental prosthesis.

11. A method of fitting a dental prosthesis in a dental site of the oral cavity of a patient comprising:

inserting in a bone socket at the dental site of the oral cavity of the patient an implant as defined in any one of claims 1 to 8, with said endosseous body innermost in said bone socket, and said head outermost in said bone socket, and mounting a dental prosthesis on said head such that the prosthesis extends outwardly of said dental site.