EP2552341A2

EP2552341A2 - Dental implant having regions with different surface structure

Info

Publication number: EP2552341A2
Application number: EP11712180A
Authority: EP
Inventors: Jost Lussi
Original assignee: Straumann Holding AG
Current assignee: Straumann Holding AG
Priority date: 2010-03-31
Filing date: 2011-03-31
Publication date: 2013-02-06
Also published as: WO2011120694A3; US20130045464A1; WO2011120694A2

Abstract

The invention relates to a dental implant comprising a shaft region (14) facing an apical end, comprising a base form that is substantially cylindrical or tapers down toward the apical end. The shaft region (14) is intended to be anchored in the bone of the patient in the implanted state. The dental implant further comprises a head region (12) adjacent to the shaft region (14) and facing a coronal end opposite the apical end. The shaft region (14) comprises an anchor region (20) disposed in the region of the apical end and a transition region (22) adjacent to the anchor region (20) and extending to the head region (12) in the coronal direction, wherein the boundary between the transition region (22) and the anchor region (20) extends 2 to 5 mm apical to the boundary between the head region (12) and the shaft region (14), and the surface structure of the transition region (22) is different from the surface structure of the anchor region (20).

Description

Dental implant with different

lächenstrukturbereichen top £

The present invention relates to a dental implant according to claim 1, a dental implant system comprising the dental implant according to claim 12 or 13 and a method for producing the dental implant according to claim 1.

Dental implants used in jawbones, for example, to fix an artificial tooth therein have been in use for some time. To date, implants made of titanium are mainly used. Titanium is biocompatible, has a sufficiently low modulus of elasticity and a relatively high strength and thus meets the most important requirements for a dental implant.

Apart from biocompatibility and mechanical properties, the osseointegrative properties of a dental implant are of great importance. Immediately after implanting the dental implant in the jawbone this is held by a so-called primary stability. Primary stability is the mechanical retention of the implant. This mechanical retention is achieved via a thread, but can also be done by undercutting, clamping effect or by friction. While this primary stability decreases over time, the jawbone permanently grows on and bonds to the dental implant. This composite, called osseointegration, establishes a so-called secondary stability, which corresponds to a biological retention. Of the Osseointegration process should run as quickly as possible in order to reduce the risk of loosening and thus possibly an outbreak of the implant. To optimize the osseointegration process, the currently used dental implants often have a roughened shaft area. Particularly good osseointegrative properties are present, for example, when the shaft area is mechanically roughened and subsequently additionally etched.

A corresponding dental implant made of a metal such as titanium is disclosed in EP-A-0388576. According to said document, the surface is subjected to sandblasting and subsequently etched with a reducing acid. Above the bone border these dental implants are usually smooth or polished.

A titanium dental implant usually has a dark, gray color and therefore differs from the natural color of the teeth. Based on this, ceramic dental implants have been proposed whose color can be adapted to the natural tooth color.

To ensure optimal osseointegration, it has also been proposed for ceramic dental implants to roughen the surface. EP-A-1982670 describes a method of making a topography on a dental implant having a surface of ceramic material. In this case, after mechanical roughening, the surface of the dental implant is etched by means of an etching solution containing hydrofluoric acid. For mechanical roughening, for example during

Sand blasting of the surface, but can in particular on ceramic dental implants

Microstructural defects arise that can result in losses in the strength of the dental implant in the affected areas.

The object of the present invention is therefore to provide a dental implant, which on the one hand has good properties in terms of primary and secondary stability in the bone and on the other hand, high strength.

This object is achieved by a dental implant according to claim 1. Preferred embodiments are given in the dependent claims. The dental implant of the present invention comprises a shaft region facing an apical end with a substantially cylindrical or tapered basic shape tapering in the direction of the apical end. The shaft region is intended to be anchored in the implanted state in the bone of the patient. Furthermore, the dental implant comprises a head region adjoining the shaft region and facing a coronal end opposite the apical end.

According to the invention, the shaft region now comprises an anchor region arranged in the region of the apical end and a transition region which adjoins the anchor region in the coronal direction and extends to the head region, the boundary between

Transition area and anchor area 2 to 5 mm apical to the border between the head area and the shaft area or apical of the nominal bone level runs and the surface texture of the

Transition region is different from the surface structure of the anchor area.

Preferably, the boundary between transition region and anchor region extends 3 to 5 mm apical to the boundary between head region and shaft region, more preferably 3 to 4 mm, and most preferably about 3.5 mm.

According to a preferred embodiment, the shaft region in the axial direction has a length of 4 to 16 mm, preferably 6 to 16 mm.

In particular, the surface structure may be described by a surface roughness.

The invention makes use of the finding that the surface structure and in particular the surface roughness in the transition region can differ from that in the anchor region without severely impairing the primary and secondary stability.

According to the invention, it is thus possible to adapt the surface roughness in the different areas to the specific requirements of the respective area.

In terms of strength, the area of the dental implant on which the boundary between the bone surrounding the dental implant and the soft tissue (the so-called bone border) lies is of particular relevance in this regard. This can be explained by the fact that the implanted dental implant in case of

Bending load, which is the decisive load situation for a dental implant, forms a clamped cantilever. With such clamped cantilevers, a force that acts at right angles to the longitudinal axis of the implant results in a moment that increases continuously until the clamping takes place. The highest load thus occurs at the clamping, ie at a dental implant at the height corresponding to the boundary between bone and soft tissue.

According to the invention, the transition region is arranged such that in the implanted state, the boundary between the bone surrounding the dental implant and soft tissue comes to rest at the level of the transition region. Since the transition region thus encompasses that region of the dental implant which is subjected to the greatest load in the implanted state, the strength of the dental implant is decisively determined by the strength of the transition region.

By the inventive arrangement of

Transition area ensures that even after a possible maximum regression of the bone of about 3 mm, the real bone boundary is still in the transition area. Thus, the risk of fracture of the dental implant is effectively reduced even in the largest possible bone loss. According to a preferred embodiment, the transition region has a uniform surface topography. Uncontrolled surface defects are therefore not present. This further contributes to greatly reducing the risk of fracture of the dental implant. According to a particularly preferred embodiment of the dental implant, the anchor area is roughened more strongly as the transition area. In this embodiment, the surface of the anchor region usually has a macrostructure, in particular a macro-roughness, such as is available in particular by sandblasting. It has been shown that this macro-roughness promotes in particular the formation of a primary stability. Said macro-roughness is superimposed with a microstructure, in particular a microroughness, such as is obtainable by etching, for example. In said embodiment, the transition region preferably has only a micro-roughness. On a sandblasting of the transition region, with which any structural defects may be associated, is thus omitted according to this embodiment. It has been shown that the fact that no macro-roughness is formed in the transition region, the primary stability is hardly affected. In addition, the formation of a blood coagulum layer and thus the ingrowth of the bone is promoted by the micro-roughness present in the entire shaft area and thus a good secondary stability is achieved.

As stated above, according to the invention, the transition region is designed in such a way or its height chosen such that in the implanted state the bone boundary, i. the boundary between the bone surrounding the dental implant and soft tissue, even after a possible maximum bone regression comes to lie in the transition region.

As implantation, the dental implant is usually sunk so deep into the bone, that the bone boundary at the height of the border between shaft area and Head area or higher, the boundary between anchor area and transition area immediately after implantation is at least 3 mm apical to the bone boundary. Thus, the risk of fracture of the dental implant is thus also reduced when the bone around the implanted dental implant regresses to a maximum, which is the case for a bone regression to a maximum of about 3 mm below the nominal or original bone boundary. The specified heights of the transition region or of the shaft region ensure that the boundary between anchor region and transition region is in any case below the real bone boundary, that is to say even in the case of maximum bone loss. This ensures even in this situation that the highest stress of the dental implant does not come to lie in the usually relatively roughened anchor area. In any case, the distance between the end of the anchor region facing the coronal end or the boundary between the anchor region and the transition region to the real bone boundary is in any case at least 0.5 mm.

According to the invention, the transition region extends to the coronal end of the shaft region. If, for example, microroughness obtainable by etching is present in the transition region, the formation of a secondary stability is promoted in this region even if the dental implant is sunk relatively deep in the bone of the patient.

A further preferred embodiment consists in that the dental implant according to the invention is made of ceramic, since in particular in the case of ceramics the described advantages of the invention come into play. As mentioned, preferably only the anchor region has a surface roughness as obtainable by sandblasting. In this regard, it is further preferred that the entire shaft region has a surface roughness obtainable by means of etching, preferably after the sandblasting of the anchor region. As a result, a tailor-made surface of the dental implant or of the shaft area is obtained.

The head region is generally configured to expand toward the coronal end. It is conceivable, for example, that the head area widens like a cup. Alternatively, however, it is also conceivable that the head region is designed substantially cylindrical. In one embodiment, the shank region of the dental implant has an external thread on its lateral surface. This intervenes in the implanted state in the bone of the patient and in particular contributes to achieving a good primary stability immediately after implantation. In addition, a larger surface is generated in the shaft area or in the anchor area and thereby also the osseointegration for the development of the

Secondary stability favors. In addition to the above-described dental implant, the present invention further includes a dental implant system comprising said dental implant formed integrally with a mounting member.

Alternatively, a dental implant system is conceivable, which includes the dental implant and a separately formed from the dental implant abutment. Here is the body part is generally rotatably mounted in a recess formed on the dental implant or on a correspondingly formed structure by means of holding means with respect to a longitudinal axis of the dental implant. This two- or multi-piece dental implant system allows for high flexibility and easy handling of the individual components during implantation and fitting of the dental prosthesis.

Another aspect of the invention relates to a method for producing a dental implant. This comprises the successive steps of a) merely sandblasting the anchor area, and b) etching the entire shaft area.

To treat only the anchor area with sandblasting, it is conceivable to mask the remaining area, ie the transition area and the head area of the dental implant. Subsequently, the masking is removed and the dental implant or its outer surface is etched in an acid bath. The invention will be illustrated with reference to the appended figures, of which:

Fig. 1 is a diagram with a through the

Dental implant system of the present invention obtainable course of primary stability and secondary stability over time, and

Fig. 2 is a dental implant according to the present invention

Invention comprising two regions with differing surface structures or surface roughness shows.

Graph 1 of FIG. 1 describes the evolution of the primary stability of a dental implant 10 in bone over time from the time of implantation, while graph 2 describes the development of the secondary stability of the dental implant 10 over time, also starting from the time of implantation. The development of the overall stability, that is the sum of the primary stability and the secondary stability, is described by graph 3. According to the invention, it has been recognized that the formation of the primary stability and the secondary stability also proceeds very well by suitable surface roughness in the transition region and in the anchor region, if the surface roughnesses in these regions differ from one another without the strength of the dental implant being significantly impaired.

FIG. 2 shows a dental implant 10 with a shaft region 14 which essentially has a cylindrical or tapering basic shape in the direction of the apical end and a head region 12 which widens in the direction of the coronal end 16 as an alternative to the embodiment shown It is also possible to design the head area cylindrical and / or to keep it very short.

The surface of the head region 12 is intended to come into contact with the soft tissue of the patient in the implanted state and is generally smooth or polished. It is also conceivable to apply a special surface roughness in this area.

The shaft region 14 adjoins the head region 12 and extends from the latter to the apical end 18 of the dental implant 10. The shaft region 14 has a surface texture in the form of a surface roughness and is subdivided into two regions, an anchor region 20 and facing the apical end 18 An anchor region 20 thus extends from the apical end 18 of the dental implant 10 to a limit 24. The transition region 22 immediately adjoins the anchor region 20 at the boundary 24 and extends to to the coronal end of the shaft portion 14.

The border 24 is such that, in the implanted state, it comes to rest apically on a bone boundary 25 which occurs at maximum bone regression during healing and also during later application, as will be explained below.

In the illustrated embodiment, the transition region 22 has a dimension, measured in the axial direction A of the dental implant 10, of 4 mm. The entire dimension of the shank region 14, also measured in the axial direction A of the dental implant 10, is 12 mm, which results in the dimension, measured in the axial direction A, of the anchor region 20 of 8 mm. This arrangement of the individual areas prevents the bone boundary 25 from coming to rest in the anchor area 20. Rather, the bone border comes in the selected dimensions even in the transition region 22, if according to ISO standard ISO 14801 with a maximum regression of 3 mm from the nominal bone boundary 29 is expected. Furthermore, due to the selected heights of the transition region 20 and the shaft region 14 or the anchor region 22 in the implanted state, the distance between the bone boundary 25 and the border 24 is still 1 mm even with maximum regression of the bone of 3 mm. At the coronal end 16 of the dental implant 10, a recess 26 is formed, in which a mounting part can be used. By holding means 28, which are formed in the recess 26, the mounting part in a known manner rotatably relative to the longitudinal axis A of the dental implant 10 is mounted. The body part may also be formed integrally with the dental implant 10.

During implantation, preferably, the shaft region 14 is completely sunk in the bone of the patient. Immediately after implantation, the implant is thus surrounded by the bone up to a nominal bone boundary 29. The real bone boundary, ie the actual boundary between bone and soft tissue, may shift during healing due to bone regression. Due to the selected configuration of the individual regions, however, the real bone boundary comes to lie within the transition region 22 during the entire healing phase of the implant.

On average, bone regression for existing implant systems is 1 to 2mm. According to ISO standard ISO 14801 is - as mentioned - with a maximum regression of 3 mm from the nominal bone boundary 29 is expected. The bone boundary 25 resulting at maximum expected bone regression is shown in FIG. As stated above, due to the selected heights of the transition region 22 and the shaft region 14 or the anchor region 20, the boundary 24 extends between the anchor region 20 and transition region 20, ie, apically, the bone boundary 25 resulting at the maximum expected bone loss.

Preferably, the distance between said bone boundary 25 and the boundary 24 is about 0.25 mm to 1 mm, particularly preferably about 0.5 mm.

The anchor region 20 and the transition region 22 each have a surface structure, wherein these differ from each other. In order to achieve the desired requirements for the strength and the development of the secondary or primary stability, the anchor region 20 is usually roughened more than the transition region 22. For this purpose, only the anchor region 20 is roughened in a first step by means of sandblasting. After the sandblasting of the anchor region 20, the entire shank region 14, that is to say both the anchor region 20 and the transition region 22, is treated by means of etching. The transition region 22 is thus treated only by etching, while the surface structure of the anchor region 20 is additionally treated by a preliminary sandblasting. Thus, the surface structure of the transition region 22 corresponds to a microstructure obtained by etching, while the

Surface structure of the anchor region 20 of a macrostructure obtained by sandblasting with a through Etching obtained, superimposed microstructure corresponds. In addition to the mentioned method, further alternatives are conceivable in order to generate surface structures. For example, a surface structure can also be obtained by grinding.

Because the shaft region 14 in the transition region 22 is treated only by etching, it has a regular surface topography. This regular surface topography ensures that a continuous strength of the dental implant 10 in the region of the transition region 22 is obtained. Microstructural defects, which can be caused by sandblasting, are thus largely absent in the transition region 22. Alternative surface structuring techniques that result in a regular surface topography are conceivable.

Corresponding methods can be readily applied by the person skilled in the art who has become aware of the present invention. As mentioned, the transition region 22 is designed such that even with a sharp decrease in the effective bone boundary, any stress peaks occurring due to an external force will still fall into the transition region. Thus, the dental implant can receive a moment occurring in the load case, without being damaged or even break off.

In the sense of rapid development of a primary stability, the dental implant moreover has an external thread 32 arranged on an outer lateral surface 30, which in the implanted state penetrates into the bone of the patient intervenes. According to the embodiment shown in FIG. 2, the largest part of the external thread is arranged within the anchor region 20.

Due to the microstructure obtained by the etching is - in the sense of rapid development of a

Secondary stability - the formation of a Blutkoagulum- layer on the surface of the shaft area promoted (see also Fig. 1).

With regard to the production of the macro- or micro-roughness, for a dental implant made of ceramic sandblasting is preferably carried out with aluminum oxide particles, in particular particles of modified aluminum oxide, such as corundum grains, with a mean particle size in the range of about 0.1-0.5 mm, preferably ca. 0.25 to 0.5 mm. Furthermore, zirconium oxide particles or other materials can also be used as the blasting material. The etching is carried out for said dental implants preferably by means of a hydrofluoric acid-containing solution, in particular at a temperature of at least 70 ° C.

Incidentally, it is also conceivable, more than two different surface structures on the

Form shaft region 14 in order to take into account further requirements with regard to primary stability / secondary stability or strength of the dental implant.

Claims

A dental implant comprising a shank region (14) facing an apical end and having a substantially cylindrical or tapering conical shape towards the apical end and intended to be anchored in the bone of the patient in the implanted state and one at the apical end opposite coronal end facing head portion (12), which adjoins the shaft portion (14), characterized in that the shaft portion (14) arranged in the region of the apical end anchor region

(20) and in a coronal direction to the anchor region (20) adjoining and extending to the head region (12) extending transition region (22), wherein the boundary between the transition region

(22) and anchor region (20) 2 to 5 mm apical of the boundary between head region (12) and shaft region

(14) and the surface structure of the transition region (22) from the

Surface structure of the anchor area (20) differs.

Dental implant according to claim 1, characterized in that the shaft region (14) in the axial direction (A) has a length of 4 to 16 mm, preferably 6 to 16 mm.

Dental implant according to claim 1 or 2, characterized in that the surface structure is a surface roughness. 4. Dental implant according to one of the preceding Claims, characterized in that the transition region (22) is arranged such that in the implanted state, the boundary between the bone surrounding the dental implant and soft tissue in the transition region (22) comes to rest.

Dental implant according to one of the preceding claims, characterized in that the transition region (22) is a uniform

Having surface topography.

Dental implant according to one of the preceding claims, characterized in that the anchor region (20) is roughened more strongly than the transition region (22).

Dental implant according to one of the preceding claims, characterized in that the dental implant is made of ceramic.

Dental implant according to one of the preceding claims, characterized in that only the anchor region (20) has a surface structure obtainable by means of sandblasting.

Dental implant according to one of the preceding claims, characterized in that the shaft region (14) has a surface structure obtainable by means of etching.

Dental implant according to one of the preceding claims, characterized in that the shaft region (14) has an external thread (32).

Dental implant according to one of the preceding claims, characterized in that the Head portion (12) widens toward the coronal end.

Dental implant system comprising a dental implant according to one of the preceding claims, which is formed integrally with a mounting part.

Dental implant system comprising a dental implant according to any one of claims 1 to 11 and a separately formed from the dental implant abutment.

Process for producing a dental implant according to one of Claims 1 to 11, characterized in that it comprises the successive steps of a) merely sandblasting the anchor region (20) and b) etching the entire shaft region (14).