The present invention relates to a tripartite monobloc dental implant.

The invention also relates to a method of producing such a monobloc dental implant.

According to the present view of dentistry, one of the possibilities for compensating for a lack of teeth is a dental implant that can be implanted in the patient's jawbone and a removable or fixed denture fixed to it. An example of the latter is a crown cemented to the implant abutment. The most common implants are two- piece implants, consisting of an implant body that can be implanted in the jaw (usually screwed) and an implant head that is fixed by a screw that passes through the implant body. Two-piece dental implants have a number of disadvantages due to their design, such as loosening of the attachment between the connecting parts and the possibility of bacterial colonisation of the resulting micrometre gaps, which can lead to inflammation. These drawbacks can be overcome with one-piece, so-called monobloc dental implants. Such a monobloc solution is disclosed, for example, in US patent US 2018/0140393, where the conventional threaded body portion and the head portion, which is at an appropriate angle to the body, are formed from a single metal block using computer-aided milling (CAD/CAM). Patent application US 2016/020002 also describes a customized monobloc dental implant specifically designed for crown fixation, where the body and head portions are designed such that the centre of the head axis is aligned with the centre of the occlusal surface of the tooth to be replaced. The material of the monobloc implants used is usually titanium, which has the structural strength and bioinert properties required for tooth replacement.

Prior art monobloc dental implants can be divided into two groups in terms of surface treatment. The first group of implants has the entire surface polished smooth. The advantage of this is that it is very difficult or impossible for bacteria that cause inflammation to adhere to the extra-bony part of the implant. The disadvantage, however, is that there is no bone integration, i.e. biological fixation. There is only mechanical fixation due to the pronounced screw threads, which is weaker than the biological connection. Such a solution can be seen, for example, in the aforementioned patent US 2018/0140393.

In the other group of implants, the part in the bone is roughened for biological healing, i.e. bone integration. However, the extra-bony part is also polished smooth to avoid bacterial adhesion. We have recognised that the fixation of a crown bonded to a smoothly polished surface is inferior to that of a crown bonded to a roughened surface. Thus, the head of the implant that protrudes from the gum should be roughened for a more stable fixation of the crown.

We have further recognised that in order to avoid adhesion of inflammatory bacteria, the neck portion of the implant in contact with the gums should not be roughened.

We have also recognised that, at the current state of the art, there are no monobloc implants that can both ensure bone integration and a more stable fixation of the crown while avoiding gingival inflammation. It is an object of the present invention to provide a tripartite monobloc dental implant and a method of producing such an implant which is free from the disadvantages of the prior art solutions. In particular, it is an object of the present invention to provide a tripartite monobloc dental implant which simultaneously ensures the bone integration of the implant and the stable fixation of the crown, as well as the prevention of gingivitis.

The essence of the invention is that the monobloc implant has a body and a head portion and a neck portion located between the body and the head portion, the surfaces of the body and head portions being roughened and the surface of the neck portion being polished smooth. According to the invention, this object is achieved by a tripartite monobloc implant according to claim 1 and a method according to claim 7.

Preferred embodiments of the invention are defined in the dependent claims.

Further details of the invention will be explained by means of embodiments and drawings. In the drawings Figure 1a is a schematic view of an exemplary embodiment of a tripartite monobloc dental implant according to the invention,

Figure 1 b is a schematic view of another exemplary embodiment of a tripartite monobloc dental implant according to the invention, and

Figure 2 is a schematic cross-sectional view of the implant shown in Figure 1a in the implanted state.

Figure 1a is a schematic view of an exemplary embodiment of a tripartite monobloc dental implant 10 according to the invention. The implant 10 is monobloc (one-piece), i.e., formed from a single element, such as a single metal block, using known machining technologies (e.g., computer-controlled milling, casting, 3D printing, etc.) as known to the person skilled in the art. Preferably, the implant 10 is made of titanium, but other bioinert materials commonly used in implantology, e.g. zirconium ceramics, may be used, as is apparent to the person skilled in the art.

The implant 10 according to the invention comprises a body 10a and a head portion 10c, and a neck portion 10b located between the body 10a and the head portion 10c. The shapes of the body 10a, the neck portion 10b and the head portion 10c may be of the usual shape for one-piece implants, depending on the implant site 10 and the patient's anatomy. For example, in the embodiments shown in Figures 1a and 1b, the body 10a has a downwardly tapered diameter to facilitate implantation of the implant 10. The body 10a may optionally be provided with fixing elements, such as pins or a thread (not shown in the figures), as is known to the person skilled in the art. The exemplary implant 10 shown in Figure 1a is axisymmetric, but the implant 10 may optionally be configured such that the body 10a is positioned along a first longitudinal axis T1 and the neck portion 10b and head portion 10c are positioned along a second longitudinal axis T2 such that the first and second longitudinal axes T1 , T2 are angled with respect to each other (see Figure 1 b). These so-called angular implants can be used effectively in particular for the replacement of maxillary teeth, where the bone loss following tooth extraction results in an unfavourable (protruding) maxillary geometry, and therefore the use of conventional axisymmetric implants is not an option in such unfavourable anatomical conditions.

The body 10a has an outer surface 12a, the neck 10b has an outer surface 12b and the head 10c has an outer surface 12c. The shape of the surfaces 12a, 12b, 12c may be e.g. conical, truncated conical, cylindrical, band or other. The surfaces 12a, 12c of the body 10a and the head portion 10c according to the invention are roughened, and the surface 12b of the neck portion 10b is smoothly polished. In the context of the present invention, a roughened surface is understood to be a surface having surface roughness (protrusions and indentations measured in micrometres) due to manufacturing or post-manufacturing surface treatment. In contrast, a smooth polished surface is a surface in which these surface irregularities have been removed either during or after manufacture, or the surface has been formed without such irregularities from the outset. It is noted that in the context of the present invention, the term "smoothly polished" is not intended to refer to polishing as a surface treatment technology per se, i.e., a smoothly polished surface in the context of the present invention includes a smooth surface created by other technologies.

The roughened surfaces 12a, 12c are preferably sandblasted, but a roughened surface 12a, 12c can be formed by, for example, chemical etching or, for example, SLA - Sand-blast, Large grit, Acid-etch technology as known to the skilled person. In a preferred embodiment, the average roughness of the surfaces 12a, 12c of the body 10a and head 10c is between 0.5 and 2 micrometres (microns), with osseointegration already significant. By average roughness is meant the arithmetic mean of the protrusions and indentations of surfaces 12a, 12c, measured at equal intervals along a given length, independent of sign, given in micrometres, as known to the person skilled in the art. Note that the average roughness of surface 12a and surface 12c may be different. For example, surface 12c may be rougher to improve crown fixation, while surface 12a has the optimal roughness required for osseointegration.

The invention also relates to a method for producing a monobloc dental implant according to the invention.

In a first step, one or more scanned images are taken of the surroundings of the site of the designed implant, including the jaw and soft tissues, such as gum 20. The one or more scans are preferably taken using CBCT (Cone Beam CT), a common technique in dentistry, which can provide an accurate image of the patient's bony part 22 as well as the overlying soft tissues (gum 20). The gingival thickness H at the site of the intended implant, i.e. the section of the patient's gum 20 at which the gum 20 will come into contact with the implant 10, is then determined from the one or more 3- dimensional scanned images.

In a particularly preferred embodiment, the gingival thickness H is determined from a 3-dimensional virtual model generated using multiple scanned images of the environment of the implant site. For example, the CBCT rotates around the patient's head to produce a series of scanned images from which a computer program generates a series of axial slices. This set of images is effectively a full spatial representation of the implant site, i.e. a 3-dimensional virtual model as known to those skilled in the art. From the data set thus generated, the 3-dimensional virtual model, a computer program can be used to provide the skilled person with the images (different views) from which the gingival thickness H can be easily determined.

In the next step of the method according to the invention, the neck portion 10b of the implant 10 is formed taking into account the thus determined gingival thickness H, by choosing a width H' of the neck portion 10b between the body 10a and the head portion 10c equal to or greater than the gingival thickness H. In this way, in the implanted state of the implant 10, the gum 20 of the patient is substantially in contact only with the neck portion 10b of the implant 10, more specifically with its surface 12b, as shown in Figure 2. By default, the boundary between surfaces 12a and 12b on implant 10 is located where the implant 10 protrudes from the bony part 22, i.e., in line with the bone surface. Knowledge of the gingival thickness H is therefore sufficient for the design of the surface 12b, since the boundary line of the surfaces 12b, 12a is determined by the depth of the implant 10.

In a preferred embodiment, the width H' of the neck portion 10b between the body 10a and the head 10c is chosen to be 0.5 - 1.5 mm wider than the gingival thickness H, i.e. with some safety margin. This safety margin is based on the fact that the implant 10 is not inserted into the bony part 22 up to the boundary of surfaces 12a, 12b, but 0.5-1.5 mm deeper. In this way, the roughened surface 12a of the body 10a will not be visible in the bony part 22 in the event of subsequent bone loss, and will not irritate the gum 20. The surface 12b of the neck portion 10b can be formed in a number of different ways. In one possible embodiment, the neck portion 10b of the implant 10 is formed by providing as a starting base a raw implant 10 of the same material (e.g., titanium) and shape as the implant 10, polished smooth over its entire surface. The raw implant will therefore only differ in surface characteristics from the final implant 10 according to the invention. The smoothly polished surface of the raw implant is then roughened, except for the surface 12b of width H' corresponding to the neck portion 10b, to form the implant 10. The roughening may be carried out, for example, using the previously mentioned known surface treatment techniques, preferably by sandblasting, by masking the surface 12b, i.e. by preserving the original smooth polished surface. In another possible embodiment, a raw implant of the same material and shape as the implant 10 is provided, roughened over its entire surface, and then the surface 12b of the raw implant corresponding to the neck portion 10b is polished smooth. That is, in this embodiment, the original surfaces 12a, 12c are retained. In another possible embodiment, the neck portion 10b of the implant 10 is formed by providing a raw implant of the same material and shape as the implant 10, roughened on the surface 12a corresponding to the body 10a, and smoothly polished on the other surfaces. The raw implant is then roughened on the surface other than the surface 12a corresponding to the body 10a and except the surface corresponding to the surface 12b of the neck 10b.

Various modifications to the above disclosed embodiments will be apparent to a person skilled in the art without departing from the scope of protection determined by the attached claims.