Patent Application
20190290402
A dental implant assembly includes an elongated inner body substantially resembling a root of the tooth, and a bone fixation member of a patient including a heterogeneous porous structure for bone growth.
The implant is the generally metallic infrastructure intended to support a dental prosthesis. It makes it possible to replace the natural pillars that are the teeth, by mechanical pillars, placed either in the mandibular bone, or in the maxillary bone.
The most important thing in placing a dental implant is getting an immediate block in the bone. Even a low mobility of the implant in the bone eventually leads to rejection, a small disparity between the implant and the bone can lead to bone resorption.
Current dental implant manufacturing techniques are traditional machining techniques, usually a threaded rod. The implant thus produced has a smooth and shiny surface. Once the implant is introduced into the bone, a threaded ring or screw is placed on the outer part which is generally a threaded rod. On said threaded ring or screw, is fixed by cement the dental prosthesis.
The main causes of rejection of dental implants are implant mobility (even low) and bone resorption due in general to the surface condition of the implant.
The state of the art can be defined by two categories of patents:
1) patents of implants made by machining, let us quote the patent of Jean-Marc JUILLET deposited on Jun. 12, 1972 under No. 72 21113 and published on Jan. 2, 1974 under No. 2.188.445,
2) other patents dealing with surface treatments for osteo integration, we quote the Zimmer Dental patent “Dental implant with improved osseointegration features” filed on 30 Aug. 2006 under the U.S. Pat. No. 807,512 B2.
The patent of Conformis Inc. “Devices and methods for additive manufacturing of implants components” filed Apr. 13, 2013 under the number WO 2013155500 A1
Eric's patent “Laser produced porous surfaces” filed Dec. 6, 2005 under the number US20070142914.
The patent of Howmedica Osteonics Corp. “Laser produced implants” filed Dec. 29, 2006 under the number US20080004709
All these patents describe means and methods of surface treatment or endospore deposition technique of Tantalum by the method of chemical deposition in vapor form, the porosity obtained in average of 35% and the partial interconnectivity.
3) implant patents made by additive manufacturing (3D printing), we will quote the patent of the University of Liverpool filed on Jun. 9, 2010 under the number WO2010146383A1.
This patent discloses a dental implant made by additive manufacturing, where a method of manufacturing by selective laser melting is explained at length, but it provides no solution to the problems of locking the implant to the mouthing and thus provides no solution to avoid rejection of the implant.
Among the numerous publications dealing with the subject of the additive manufacturing of dental implants, the following are in agreement on the undeniable advantages of performing dental implants by additive manufacturing in compatible organic materials of the Ti6Al4V type in different grades:
“Direct Metal Laser Sintering Titanium Dental Implants: A Review of the Current Literature” published 1 Dec. 2014 in International Journal of Biomaterials.
“Histomorphometric Evaluation of Direct Laser Metal Forming (DLMF) Implant Surface in the Type IV Bone: A Controlled Study in Human Jaw” Published Jul. 25, 2013 in the journal POSEIDON Journal “Manufacturing of Bioactive Porous Ti Metal with Structure Similar to human Cancellous Bone by Selective Laser Melting “Published Dec. 2, 2010 in the journal BDA Bioceramics Development and Applications.
Additive manufacturing and for some additive technologies specifically (SLM, EBM, SLA) presents several possibilities for controlling geometry, porosity, inter connectivity and 3D architecture through changes in the manufacturing parameters. Main parameters for selective laser melting technology:
The Selective Laser Melting (SLM) selective metal powder laser melting process, the SLM name will be maintained throughout the patent text.
SLM is a process used to manufacture complex three-dimensional components from metal powders, ceramic or polymer powders. The technology is mature and already used in the aerospace and medical industry to manufacture complex components with high densities and homogeneity. We cite one of the first patents of the Fraunhofer Institute in Germany, filed Oct. 27, 1997 under the number WO1998024574A1, which describes the SLM process in a more precise way.
The invention also relates to the method of manufacturing an assembly as described above, by stacking layers of metal powders and/or non-metallic, selectively fused by concentration of a power source.
According to the invention, this method comprises a step of preparing the mobility of the fastening element relative to the inner body.
The
The
The
The
The present invention describes a system and its method by additive manufacturing of dental implants with heterogeneous and self-locking porous structures which advantageously provides a double answer to the problems inherent in dental implantology, namely osseointegration and mobility of the implant. during his pose. For this, the present invention provides a self-locking dental implant with heterogeneous porous structures.
The dental implant described in the present invention is composed of a central body which represents the root rooted in the jawbone, the head of the implant can be rounded, flat, hollow, or any particular shape to receive the prosthetic pillar. In another embodiment, the implant may be integral with the implant abutment. The one-piece realization of the implant and the prosthetic abutment will be done by additive manufacturing, particular angles of curvature between the implant and the abutment are calculated following a digital processing of three-dimensional images of the morphology of the jaw.
It is self-locking in the bone in which it is implanted thanks to the porous bone fixation element, which is made movable between a passive row position allowing insertion of the implant into a perforation made in the bone, and a position deployed active where this porous element fills the cavities existing between the internal body of the implant and the bone and will be colonized by this bone during bone growth.
This mobility of the fastener may be caused by thermal expansion, and/or by a tool as will be explained in more detail in the following.
The fastener may be in the form of a heterogeneously porous helical-shaped coating for certain threaded implants, but this coating may be of different shapes and geometries that encase part or all of the implant. dental implant being preferably disposed in the portion of the dental implant in contact with the bone.
Said structure has a porosity of between 30% and 80%, a pore size of between 100 μm and 500 μm and a pore distribution of between 500 μm and 700 μm with total interconnectivity. In a preferred embodiment the porosity between 60% and 70%, the pore size between 200 microns and 300 microns with a distribution of porosity between 100 microns and 600 microns and a total inter connectivity. Its parameters are thus close to the characteristics of the human bone in the maxillary and the mandible.
The body of the dental implant and its fixing element are made by stacking layers of metallic or nonmetallic powder, selectively fused together. In the case of titanium/aluminum/vanadium metal powder, the thickness of the layers is generally 30 μm. One of the additive manufacturing techniques selected for our example is SLM technology, this embodiment is not limiting, other deposition technologies can be deployed.
A digital file of the dental implant is produced by a three-dimensional design software either according to standard models and standards or according to a particular embodiment: in this case, the shape of the dental implant, namely its height, its low section, its high section are determined more precisely.
In another embodiment, the dental implant may have the exact shape of the tooth, this mode is preferred in the case of replacement of a tooth just after extraction. A “customized” implant is thus produced according to the morphology and the mechanical properties of the tooth of the patient to be replaced and/or of the bone in which the implant will be integrated.
In this file, the fixing element is predefined with a particular thickness of between 1 and 2 mm, in a preferred embodiment the thickness is between 0.8 mm and 1.5 mm.
Several forms of porosity can be selected with the possibility of defining pore distribution zones of different sizes.
Ideally, the porous structure forming the fixing element has a porosity of between 30% and 80%, a pore size of between 100 μm and 500 μm and a pore distribution of between 500 and 700 μm with total interconnectivity.
In a preferred embodiment the porous structure has a porosity between 60% and 70%, the pore size between 200 microns and 300 microns with a distribution of porosity between 100 and 600 microns and a total inter connectivity.
The basic cell or unit cell constituting the porous structure made by stacking layers, is of geometric shape in three dimensions (x, y, z), the unit cell is formed by at least three edges with an angle opening d at least 10°, such as a trihedron, and the unit cell may be of regular or irregular shape in the form of a pyramid, tetrahedron, cubic, octahedron, icosahedron, dodecahedron and without shape limitation. In a preferred embodiment, the unit cell will be of reinforced dodecahedron form.
In another embodiment, the unit cell is formed of 12 edges with edge opening angles of 30° to the vertical axis or construction axis. The edges can be regular or irregular depending on the density of the mesh and the desired porosity.
The material used for the production of such an implant is a biocompatible material of pure metal or metal alloys of the cobalt, tantalum, niobium chromium type, metal-ceramic or organo-metal or organo-ceramic compounds or a metal organo-ceramic combination.
For the realization of the internal body, two alloys of materials have been preferentially used:
a titanium alloy aluminum vanadium Ti6Al4V grade 23, with an oxygen content<0.2%,
A combination of a titanium alloy advantageously mixed with a zirconia-based material.
For the realization of the fixing element, three alloys were used:
A titanium alloy aluminum vanadium Ti6Al4V grade 23, with an oxygen content<0.2%,
A combination of a titanium alloy advantageously mixed with a nickel-based alloy
And in a preferred embodiment, the inner body and/or the porous fastener consist of a biocompatible material containing a zirconia-titanium composite/binary material with zirconia powder concentrations of between 5% and 25%, which is obtained during the shaping of this internal body and/or fastening element by additive manufacturing by selective melting of layers of powders, powders advantageously consisting of a mixture of nanometric particles of zirconia (or any other ceramics) and particles micrometric titanium (or any other metal).
Once the shapes of the inner body and of the fixing element have been determined, the porosity of the selected fastening element, the unit cell defining this porosity, also chosen, the constituent materials of these chosen, and the mobility means of the determined fastening element, the embodiment by additive manufacturing, and in a preferential mode by the SLM technology can be launched.
The dental implants system with heterogeneous porous structures is made by selective fusion of biocompatible metal powder with a particular embodiment of the implant surface.
The autoblocking system of the implant can be achieved by a mechanical means external to the implant or internal and then performed simultaneously with the implant and which pushes the helical portion to the bone seat of the implant.
The fixing element which advantageously has a helical profile in order to be distributed over the whole of the external surface of the implant, and which is made movable between the inactive, stored and deployed active positions, can be integral (a). or not integral (b) of the central nucleus or internal body of the dental implant:
(a) Solidary: the helicoidal part is held by at least four integral fixation points of the central pillar or inner body, at the laying of the dental implant, a suitable tool comes to chase the fixing points in order to release the helicoidal part which just stick to the walls of the dug out of the implant. In this case, it may be provided that the porous fastening element is made in a pre-stressed form and fixed in its pre-stressed form to the inner body by the attachment points, so that when the fixation, it can be released and expand naturally with respect to the internal body to adopt its active position deployed
(b) Not secured: the assembly of the helical portion on the central pillar is for example by lateral compression by a suitable tool and the installation of the dental implant, the assembly is released.
Other means of blocking the fastening element in the hollow formed in the bone, can be envisaged, for example, the thermal fixation by thermal expansion of the fastening element when inserted into the bone. of the patient and subjected to his body temperature (it is then expected a thermal expansion of the fastener greater than that of the internal body of the implant, at least 20% for example) or chemical fixation in reaction to an additive or in contact with the implant medium. For example, the fastener may be a moisture-responsive polymer that will swell when exposed to the moisture of the patient's body once inserted into the bone.
Another mode of blocking can be envisaged, with a stoichiometric mixture of nickel/titanium forming Nitinol, a shape memory alloy which has a coefficient of thermal expansion and elasticity higher than titanium. In this case, the porous fixing element may consist of Nitinol and the internal titanium body.
The dental implant described in the present invention is composed of a central body which represents the core of the implant (1-1), the head of the central body may be rounded, flat, hollow, or any particular shape to receive a implantary abutment, in another mode the implant core may be integral with the implant abutment and made in one piece in additive manufacturing with particular angles of curvature according to the morphology.
A coating with heterogeneous porous structures (1-2) of helical shape for some implants but this coating can be of different shapes and geometries that come in dressing of part or all of the dental implant.
In the example of
The particular structure of the inner body (2-2) and that of the fastening element are then defined, again without the pores (2-3).
Different porosities are then defined for the fastener (2-4, 2-5, 2-6).
And after having chosen the porosity adapted to the particular case (as a function of the mechanical properties envisaged with such a structure and such porosity), a file is defined which joins the particular internal body with its complete structure, and the fixing element with porosity. desired (2-7).
The implant is then made by additive manufacturing according to the SLM technology already described, the implant (2-1) is made by a three-dimensional design software according to the morphology of the patient, the height and the section of the implant are thus defined.
In this example, the fixing element is made movable between the position shown in
In this case, the fastening element expands so that its outer wall flushes the ridges of the flat spiral band of the body and thus comes into contact with no gap in the bone cavity.
It can be provided that the fastening element is connected to the body by a bridge of breakable material (for example of smaller thickness) or a chemical bridge.
Or that the fastening element can be spaced radially relative to the inner body that contains it.
This is the embodiment shown in
The porous part (2-3) is predefined with a particular thickness of between 1 and 2 mm from the central body of the implant (2-2).
Several porosity shapes can be selected (2-4; 2-5; 2-6) with the possibility of setting the pore distribution zones of different sizes.
The basic cell or unit cell (3) is of geometric shape in three dimensions (x, y, z), the unit cell is formed by at least three edges (3-1), with a rounded-shaped cladding (3-). 2), this form is not limiting, with an angle opening of at least 10°, and the unit cell may be of regular or irregular shape in the form of a pyramid, tetrahedron, cubic, octahedron, icosahedron, dodecahedron and without limitation of form.
The distribution of unit cells (3-3) can be regular or irregular, with opening angles of at least 10°. After dressing the unit cells (3-4) the porous part is formed.
An implant diameter drill tapped the bone, because of the low density and natural porosity of the maxillary and mandibular bone, the threading is approximate. At the mouth of the dental implant (4-2), small cavities appear between the body of the implant and the bone see detail (4-1). Upon release of the fastener (4-4) all small cavities are filled, see detail (4-3).
The numerical execution flow of tasks is summarized in
Step 1: The digital file of the dental implant is made by a three-dimensional design software (2-1), the shape can be standardized according to a pre-defined or customizable model.
Step 2: delimiting the part of the fixation element (2-3) and the solid part representing the body of the implant (2-2),
Step 3: Generate a type of unit cells or a combination of said base cells (2-4; 2-5; 2-6). Which cells are characterized by the geometry thus produced has the advantage of controlling the porosity and its density.
Step 4: Realization of the central implant assembly+fixing element (2-7) having a porous surface advantageously heterogeneous.
In this example, the inner body (5-1) has a hollow frustoconical shape defining a wall thickness, provided with an external thread 5-2, and comprises two opposite grooves 5-3 made in its wall thickness and following a helicoidal profile, the fastening element 5-4 having the shape of a thick ribbon twisted according to the helical profile of the two grooves and a shape complementary to those ci.
The fastening element 3-4 comprises an upper and central longitudinal recess 5-5 for the passage of a spacer, such as the screw for placing the implant.
The first two views of this
It can be seen in
Example of the implant parameters of the Dental Implant and Fixation Device Set on an SLM 125 HL machine from the manufacturer SLM SOLUTIONS GMBH
Preferably, it is recalled that:
the assembly according to the invention is produced by stacking layers of metallic or non-metallic powders, fused selectively by concentration of a source of energy.
the assembly according to the invention is characterized in that said fixing element comprises a heterogeneous structure having a porosity of between 60% and 80%.
the assembly according to the invention is characterized in that said fixing element is formed by a multiple of a unit cell, said unitary cell is formed by at least three edges and opening angles of at least 10°.
the assembly according to the invention is characterized in that said dental implant has either a cylindric-conical geometry or the morphological shape of the tooth.
the preferred material according to the invention is derived from the fusion of a homogeneous and stable mixture of microscopic titanium or Ti6Al4V powders and nanoscopic yttria zirconia powders in which:
with a particle size of between 30 and 70 nm and a median size of between 65 and 85 nm and a minimum size of greater than 20 nm.
| Number | Date | Country | Kind |
|---|---|---|---|
| PCT/FR2016/053154 | Nov 2016 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2016/053154 | 11/30/2016 | WO | 00 |
