CZ2016225A3 - A dental implant shank - Google Patents

Abstract

The stem of the dental implant consists of an upper attachment part (1) for attachment of the superstructure with the dental crown and from the lower intrabony part (2) for attachment in the jaw bone tissue. Basic body (4) of the lower intraosseous part (2) has an applied composite on its outer surface surface sandwich layer, formed by the bottom layer (5) with porous structure, directly emerging from the material of the basic body (4) intraosseous part (2), and a peripheral polymer layer (6) formed by biodegradable material and admixture of antibiotics. The porous structure of the bottom layer (5) is formed by a regular and/or irregular trabecular structure with a labyrinth of open interconnected cavities, while the thickness of this lower layer (5) ranges from 180 to 450 μm in size cavities depending on the total width of the lower layer in the range of 60 to 200 μm. The peripheral polymer layer (6) consists of a soft surface layer biodegradable material based on polylactic acid with a decay time in the order of 2 to 12 weeks, while the thickness of this peripheral polymer layer (6) varies with respect to the common dimensions of dental implants in the range of 50 to 200 μm.

Description

Technical field

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a shaft of a dental implant serving as an artificial tooth root replacement and consisting of an upper attachment portion for attaching a dental crown attachment and a lower intra-bone portion for attachment in the jaw bone tissue.

BACKGROUND OF THE INVENTION

The current trend in the surface treatment of dental implants is bioactive materials, accelerating the healing processes and actively ensuring the formation of strong bonds between the living tissue and the implant. The basic condition for the formation of binding fields between the surface of bioactive material and bone tissue is the formation of a thin peripheral layer enriched with calcium and phosphorus, which is the result of the interaction between the implant and body fluid on the surface of the bioactive material. Polymeric materials, which are widely used in biomedical applications due to their high variability of properties, and composite materials, which have the main advantage of being able to optimize mechanical and biological properties through the appropriate choice and combination of input materials, also have significant positions in this field [Ramakrishna, S. et al. al. Biomedical applications of polymer composite materials: a review. Composites Science and Technology, 2001].

Bioactive compounds or other biologically active substances that increase the surface bioactivity and stimulate the healing of implants can also be incorporated into the coating structure of these types. At the same time, the development of surface layers with lower values of elastic moduli may also favorably influence the distribution of mechanical stresses at the interface of the implant with the tissues [Hedia, H. S. Effect of cancers on the functionally graded dental implant concept. Bio-Medical Materials and Engineering, 2005], The surface properties of an implanted implant that significantly affect tissue interaction and the degree and quality of osteointegration include chemical composition and physical properties of the surface (eg wettability) , surface energy, topography, roughness, stiffness, etc.) [Le Guehennec, L. et al. Surface treatments of titanium dental implants for rapid osseointegration. Dental Materials, 2007].

In terms of the chemical composition of the implant surface, the presence of hydroxyl groups, which provide a hydrophilic surface, is beneficial. In the case of titanium implants, an inert nanolayer of titanium oxides (predominantly TiO2) with high surface energy is present on the surface. [Schwarz, DM et al. Titanium in Median: Material Science, Suface Science, Engineering, 2001]. At the same time, based on the results of many studies, it can be stated that primary fixation and long-term mechanical stability can be ensured by increasing surface roughness at macro, micro and nano levels.

Currently, the most common implants with a surface roughness of 1 to 2 µm [Albrektsson, T. et al. The Impact of Oral Implants - Past and Future. Journal ODA, 2005]. The current new trend is the so-called nanomaterials with structural elements ranging from 1 to 100 nm, which are already dimensionally aligned with the structural elements of bone and thus play an important role in protein adsorption, adhesion and cell proliferation in the primary stage of implant healing [Zhang , L. et al. Nanotechnology and Nanomaterials: Promises for improved tissue regeneration. Nano Today, 2009].

Implant surfaces can be mechanically and chemically modified in various ways to ensure desirable properties (hydrophilicity, bioactivity) or to achieve a certain topography. Hard sand particles are used to sandblast the surface at high speed, significant factors are material, particle size and shape, pressure, time, etc. The most commonly used particles are the highly discussed AI2O3 [Diniz, MG et al. Characterization of titanium surfaces for dental implants with inorganic contaminant. Brazilian Oral Research, 2005], T102 [Mustafa, K. et al. Determining optimal surface roughness of TiO ₂ blasted titanium implant material for attachment, proliferation and differentiation from cell derived from human mandibular alveolar bone, Clinical Oral Implant Research, 2001], and positively evaluated calcium phosphate-based materials - Ca / P [Choi, CR et al. Bone Cell Responses of Titanium Blasted with Bioactive Glass Particles. Journal of Biomaterials Applications, 2009]

Currently used methods of chemical etching treatment include pickling the titanium surface with hydrofluoric, sulfuric, nitric or hydrochloric acid. They can partially remove impurities from previous treatments (eg by sanding) and at the same time obtain a microporous surface formed by depressions [SzmuklerMoncler, S. et al. Biological properties of acid etched titanium implants: Effect of sandblasting on bone anchorage. Joumal of Biomedical Materials Research Part B, 2004], the acid-etched surface has been shown to improve osteointegration of implants. Other chemical modifications used are, for example, alkaline surface treatments that cause nucleation of apatite on the periphery further increasing by the consumption of calcium and phosphate ions from surrounding tissue [Kim, H. et al. Preparation of bioactive Ti and its alloys via simple chemical surface treatment. Journal of Biomedical Materials Research, 1996], fluoridation or anodic oxidation, which is an electrochemical surface treatment in a strong inorganic acid environment that leads to a thickening of the oxide layer to form micro or nano pores.

Surface treatments of dental implants for osteointegration are also known from a number of patents. For example, WO 2008/014742 discloses a titanium or titanium alloy implant having a porous coating having a pore size in the range of usually from 100 to 2000 µm, the porosity of the coating being up to 80% by volume.

Dental implants that are coated with medicaments, such as anti-inflammatory or anti-infectious antibiotics that are released into the body of the patient, such as from US 2012208148, are also known from patent publications. Another US 2015147720 also discloses a dental implant whose root portion it is provided with a collagen coating and an antibacterial coating. The subject of WO 2013/119058, if understood from the abstract, is in particular the types of antibiotics used in the dental implant and not the actual treatment of its surface treatment. A certain disadvantage of all these known dental implants whose surface layers contain antibiotics to prevent inflammatory processes and possible infections is their relatively difficult manufacture and consequently higher production costs, and in particular the fact that the release of antibiotics from their surface is essentially uncontrolled, which everything carries negative impacts on the patient.

Other patents dealing with a similar area of dental implants are US 2009215007, where the implant is solved by a composition of different parts and additionally without a biodegradable layer. US 2012208148 deals with the application of a drug substance between the threads of a screwed implant and does not solve the porous layer. The claims and US 8297974 B1 utilizes a porous body with an internal cavity to transport growth promoting substances through the internal cavity of the implant and thus does not solve the trabecular layer as a scafould for the biodegradable layer and subsequent bone cell growth. US 2016058530 addresses the porous structure of the implant only as a single unit without further composition with a biodegradable layer and inner filler. Among others, there are others, for example US 4178686, US 2015147720, US 2015132719, etc., which also deal with intra-bone parts of dental implants, but they deviate significantly from the proposed solution.

SUMMARY OF THE INVENTION

The above-mentioned disadvantages of the prior art in this field are largely eliminated by a dental implant shaft consisting of an upper attachment portion for attaching a dental crown superstructure and a lower intra-bone attachment portion for jaw bone constituting its base body according to the present invention. . The principle of the invention consists in that the base body of the lower intra-bone part of the shaft of the dental implant is provided on its outer surface with a composite surface sandwich layer formed directly from the surface of the base dental implant.

bodies protruding from the backsheet with a porous structure and a peripheral polymer layer formed of a biodegradable antibiotic-containing material.

By having the porous structure backsheet directly protruding from the surface of the dental implant stem body of the present invention, the stem base body and the backsheet can be formed in a single manufacturing operation in a substantially simple 3D printing process as a single assembly. The pore volume of the backsheet may typically be in the range of 40 to 80% by volume.

Further, the porous structure of the backsheet is preferably formed by a regular and / or irregular trabecular structure with a labyrinth of open interconnected cavities to optimally form a carrier scaffold for osteoconductive bone cell growth, the thickness of the backsheet being in the range of 180 up to 450 µm and cavity size depending on the overall width of the backsheet in the range of 60 to 200 µm.

The invention further provides that, in order to ensure successful implant healing, the peripheral polymer layer applied to the outer edge of the porous backsheet structure is preferably a soft surface layer of a biodegradable polylactic acid material having a disintegration time of the order of 2 to 12 weeks. The thickness of this peripheral polymer layer is in the range of 50 to 200 µm, taking into account the conventional dimensions of dental implants.

Also preferably, the peripheral polymer layer forms a continuous surface over the entire base body of the lower intra-bone portion of the implant shaft with penetration into the porous structure of the backsheet and contains antibiotics at a concentration of 5-10% by weight in the deposition phase.

The penetration depth of the peripheral polymer layer into the porous structure of the backsheet depends on the manner in which the peripheral polymer layer is formed. If the peripheral polymer layer is formed by immersing the base body of the lower intra-bone portion in its bath, the peripheral polymer layer may penetrate into the porous structure of the bottom layer over its entire thickness depending on the immersion time. In the case of • • ······················

- 6 peripheral nanofibrous polymer layer, when this peripheral polymer layer is applied to the base body of the lower intra-bone part of the shaft by means of fibrillation, its penetration into the porous structure reaches max. 20% of the thickness of the lower layer. The material of the base body may be, for example, titanium, titanium alloys, as well as alloys of other biocompatible metal materials, such as Ta, Nb, etc., or biocopolymers, etc., suitable for this purpose.

The advantage of the solution according to the invention is especially the fact that as the biodegradable material of the peripheral polymer layer gradually dissolves, antibiotics will be released evenly at the site of tissue damage, preventing any inflammation and necrosis. Therefore, it is not usually necessary to increase the dosage of antibiotics that will affect the whole organism, but to target the dosage for an absolutely necessary and at the most limited concentration. Another benefit of the solution is also to maximize the contact surface of the implant with bone tissue and to reduce the cost of manufacturing these implants.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further illustrated by the drawings of an exemplary embodiment of a dental implant shaft according to the invention, wherein:

Fig. 1 - longitudinal section of the dental implant stem;

Fig. 2 - detail of the shank of Fig. 1 with a regular porous structure of its lower layer;

Fig. 3 - detail of the shaft of Fig. 1 with an irregular porous structure of its lower layer.

An example of a particular embodiment of the invention

The dental implant shaft, in this exemplary push-in embodiment, consists, as shown in FIG. 1, of an upper attachment part 1 for attaching a dental crown superstructure consisting of a hollow circular body 7 with an internal thread and an outer octagon 3 and a lower intra-bone the jawbone portion 2 formed of a conical shaped body 4 with a circular cross-section with a diameter of 4.2 to 3.2 mm. This • · • ·

the base body 4 of the lower intra-bone part 2 is provided on its outer surface with a deposited composite surface sandwich layer consisting of a bottom layer 5 with a porous structure of titanium alloy and a peripheral, in this case nanofibrous, polymer layer 6 composed of a biodegradable antibiotic material.

As can be seen in greater detail in FIG. 2, the porous structure of the backsheet 5 is formed by a regular trabecular structure with a labyrinth of open interconnected cavities formed together with the base body 4 by the 3D printing method of Ti6Al4V-Rematitan titanium alloy. The thickness of the backsheet 5 in this particular embodiment is 240 µm and the cavity size is 80 µm.

The peripheral nanofiber polymer layer 6 consists of a soft surface layer of a biodegradable polylactic acid material, in this particular embodiment, containing by weight 90% of polylactide - PDLLA and 10% of antibiotics - Vancomycin with a disintegration time of 3 to 6 weeks. The thickness of this peripheral nanofibrous polymer layer 6 is here in particular 70 µm and forms a continuous surface over the entire base body 4 of the lower intra-bone part 2 of the implant shaft with penetration into the porous structure of the lower layer 5 to a depth of 40 µm. This peripheral nanofibrous polymer layer 6 is applied by electrospinning by means of fibrillation in the form of a disordered fiber network with a fiber thickness of approximately 60 to 500 nm. The total thickness of the composite surface sandwich thus formed is 280 µm.

As can be seen in greater detail in FIG. 3, the porous structure of the backsheet 5 may alternatively be formed by an irregular trabecular structure and, if desired, the porous structure of the backsheet 5 may alternatively be formed by a combination of both regular and irregular trabecular structures. structure.

Industrial applicability

The solution according to the invention can be widely used in dentistry, namely in the field of dental implantology.

Claims (4)

Dental implant shaft, comprising an upper attachment portion (1) for attaching a dental crown attachment and a lower intra-bone portion (2) for attachment to the jaw bone tissue formed by its base body (4), characterized in that the base body (4) the lower intra-bone portion (2) is provided on its outer surface with a composite surface sandwich layer consisting of a lower layer (5) with a porous structure directly projecting from the base body (4) base material (2) and a peripheral polymer layer ( 6), consisting of biodegradable material with admixture of antibiotics. Dental implant shaft according to claim 1, characterized in that the porous structure of the backsheet (5) is a regular and / or irregular trabecular structure with a labyrinth of open interconnected cavities, the thickness of the backsheet (5) being in the range of 180 up to 450 pm. Dental implant shaft according to claim 1, characterized in that the peripheral polymer layer (6) is a soft surface layer of a biodegradable polylactic acid-based material with a disintegration time of the order of 2 to 12 weeks, wherein the thickness of the peripheral polymer layer (6) ranges from 50 to 200 µm. Dental implant shaft according to claims 1 to 3, characterized in that the peripheral nanofiber polymer layer (6) forms a continuous surface all over the base body (4) of the lower intra-bone part (2) of the implant shaft with penetration into the porous structure of the lower layer (5). ), wherein it contains antibiotics at a concentration of 5 to 15% by weight in the application phase.