EP1915102A2

EP1915102A2 - Tool for producing and preparing a hole for accommodating dental implants and corresponding dental implant

Info

Publication number: EP1915102A2
Application number: EP06776688A
Authority: EP
Inventors: Roland Streckbein; Stephan Meyer; Martin Ellerhorst
Original assignee: Bego Implant Systems & Co GmbH; Bego Implant Systems & Co KG GmbH
Current assignee: STRECKBEIN, ROLAND
Priority date: 2005-08-09
Filing date: 2006-08-08
Publication date: 2008-04-30
Also published as: DE202006020925U1; WO2007017257A3; DE102005038038A1; WO2007017257A2

Abstract

The present invention relates to a drill for making a hole in a jawbone for anchoring a dental implant, the drill consisting of a shaft and a conical cutting piece, as well as a thread former for producing a screw thread in a hole in a jawbone for anchoring dental implants, the hole being in the form of a conical stepped hole, which tapers from a conical starting section at the opening of the hole towards an end section. The present invention also relates to a two-part dental implant, comprising a first threaded part (10) that can be screwed into a jawbone and a second part (20) which is attached thereto for holding a dental crown. In order to develop tools for producing and preparing threaded holes in jawbones and a corresponding implant which result in a higher probability of success with regard to durability and rapid incorporation of the implant, it is proposed that the drill be a stepped drill in which the cutting piece consists of a first conical front section and a likewise conical base section attached thereto, the diameter of the drill increasing at the transition from the front section to the base section gradually by an amount that falls between 10 % and 25 % of the diameter of the front section immediately prior to the transition to the base section. It is proposed that the thread former has a first front section and a second section attached thereto, the first section being between 5 and 15 mm in length and the second section being at least 1.5 mm in length, and the second section having finer threading than the first section. With regard to the dental implant, it is proposed that the threaded part (10) has two-step threading corresponding to the thread former.

Description

Tools for making and preparing a bore for receiving dental implants and corresponding dental implant

The present invention relates to tools for the preparation and preparation of bores for the anchoring of dental implants and a corresponding dental implant.

In particular, the present invention relates to a drill for making a bore in jawbone for the anchoring of dental implants, consisting of a shank and a conical cutting part. Corresponding drills are already known in the prior art. Likewise, the present invention relates to a thread former for producing a thread in a bore of a jaw bone for anchoring dental implants, in particular in a bore made with a drill according to the present invention, although it would also be possible in principle, the thread former according to the invention in one to use with other drilling tools, but in the result identically produced bore.

Finally, the present invention also relates to a dental implant, which consists of a threaded part and a second, a tooth crown-bearing part, which are connected to each other by means of a clamping screw, wherein the Threaded portion is matched to the thread produced in the thread of the present invention in the bore of the jawbone.

Corresponding drills, thread formers and dental implants are known in principle in the prior art. However, the successes achieved with the corresponding implants are very different. On the one hand, this is due to individual differences in bone structure, bone durability and bone growth in the respective patient. Furthermore, the durability depends on the thread shape, the diameter and the length and profile depth of the thread produced in the jawbone, especially in the case of continuous loading, and finally the healing process also depends on individual factors. However, the inventor has found that, regardless of the aforementioned and only conditionally influenced factors, by the measures according to the invention better durability can be achieved even with intensive loading of the implants and a faster healing process. The invention is therefore an object of the invention to provide tools for the manufacture and preparation of threaded holes in jawbone and a corresponding implant, which cause a higher probability of success in terms of durability and faster healing of the implants.

This object is achieved with a dental implant, which is suitable for anchoring in a hole in a jawbone, with

a. a first lower portion for anchoring the dental implant in the cancellous area of the jawbone,

b. a second, upper section for attaching the dental implant to the cortical top area of the jawbone,

and that is further developed by

the first lower portion is provided with an external thread having a first pitch, the second upper portion is provided with an external thread having a second pitch smaller than the first pitch, and between the first and second sections a transition section is arranged in which a thread is formed whose geometry changes continuously following the first section from the geometry of the first thread for connection to the second section in the geometry of the thread of the second section ,

The dental implant developed in this way is based on the knowledge that, in order to achieve satisfactory primary stability and to enable rapid and reliable healing, it is advantageous if an external thread is provided on the dental implant both in the cancellous bone and in the anchoring region in the cortical bone. However, the external thread must be adapted to the specific properties of the surrounding tissue and this is inventively achieved in that the external thread for the cancellous region has a greater slope than the external thread for the cortical region. In the attachment area of the oral mucous membrane, a smooth area can be provided or partially a thread and partially a smooth surface can be formed here.

As a further aspect of the dental implant according to the invention, the transition between the two external thread regions is continuous, ie a transition region is arranged between the two external thread regions, in which the pitch of the external thread changes continuously, that is to say without steps. In this transition region, the outer thread geometry of the first lower section is assumed at the border adjacent to the first lower section, and this geometry is continuously changed so far that the outer thread geometry of the second upper section is up to the border adjacent to the second upper section of the dental implant Section is reached. In this way, the invention achieves the advantage that when screwing in the dental implant according to the invention a targeted displacement of bone tissue takes place, which causes a desired compression of the bone tissue around the implant and thus positively influence the Primärstabili- and the healing. - A -

The dental implant can be further developed by the first lower portion is conically tapered downwards. Such a conical design also causes a favorable displacement of bone tissue when screwing the dental implant according to the invention and can thus also achieve a favorable compression of the bone tissue to the dental implant.

It is particularly preferred if the conical taper is achieved by the core diameter of the thread tapers conically from top to bottom and the outer diameter of the thread is cylindrical. With this embodiment, starting from the lower tip, the thread depth of the dental implant in the first lower portion is thus reduced towards the top by the core diameter increasing from bottom to top with the outside diameter of the thread remaining the same. This embodiment causes compression of the surrounding bone tissue by displacement with the core of the thread. At the same time, the increased thread depth in the tip region of the dental implant thus formed can be used for a particularly favorable connection in cancellous bone, which likewise typically has a low density in the depth of the jaw bone than in the edge region of the jaw bone.

Alternatively to the aforementioned embodiment, the conical taper can also be achieved by the outer diameter of the thread tapers conically from top to bottom and the core diameter is cylindrical. In this embodiment, the core of the thread does not cause a progressive displacement, but this displacement is achieved by the threaded threads, which conically widen from bottom to top with respect to their outside diameter. The thread depth of this embodiment thus increases from the lower tip to the top.

Still further alternatively, the conical taper can be achieved by tapering the outer diameter and the core diameter of the thread from top to bottom. In this embodiment, the displacement and compression of the bone tissue during screwing takes place both by the core area of the thread as well as the flanks of the thread. The embodiment makes it possible to keep the thread depth constant over the entire first lower portion by making the conical taper of the outer diameter and the core diameter at a coincident angle. Moreover, in this embodiment, however, the thread depth may also decrease or increase, as viewed from the lower tip of the dental implant, by making the conical taper of the outer diameter smaller or larger than that of the core diameter.

According to a further preferred embodiment, the core diameter and / or the outer diameter of the thread in the second upper portion is cylindrical. This geometric design of the second upper portion of the dental implant is advantageous for a damage-free and firm anchoring of the dental implant in the cortical region and also allows a good seal of the dental implant against the oral cavity by a firm attachment of oral mucosa and cortical bone to the implant. In this case, the cylindrical configuration, as explained above with respect to the first lower section, can be effected by a cylindrical geometry of the core diameter or a cylindrical geometry of the outer diameter, wherein correspondingly the outer diameter or core diameter are each not cylindrical, for example convex or otherwise shaped can. It is particularly preferred, however, to form both the core diameter and the outer diameter of the thread in the second upper section cylindrical.

With regard to the above-mentioned drill, the above-mentioned object is achieved in that the drill is designed as a stepped drill by the cutting part consists of a first conical front portion and an adjoining, also conical base portion, wherein the drill diameter graded at the transition from the front portion to the base portion. tig extended by an amount that is between 10% and 25% of the diameter of the front section immediately before the transition to the base section. To make the bore conical is known in principle. According to the invention, however, a conical stepped bore is produced, wherein the (near the jaw bone) near-surface base portion due to the step-like enlargement produces an average 10-25% larger, but slightly conical bore, while the subsequent, deeper introduced into the jaw bone section of the bore has a correspondingly smaller diameter with an overall conical shape. The front portion has expediently a length between 5 and 15 mm and the base portion has a length of at least 1, 5 mm, preferably of about 3 mm. With regard to the implant to be inserted later, or with respect to the thread former to be used for further preparation of the bore, the diameter of the enlarged bore portion which covers the jawbone area close to the surface, ie the corticalis of the jawbone, is about 5%. smaller than the associated threaded portion of the thread former, while due to the stepped tapering of the bore (as viewed from outside to inside), the diameter of the deeper portion of the bore, which essentially covers the so-called cancellous bone of the jaw bone, by about 15-30 % is smaller than the diameter of the corresponding section of the thread former and the implant to be subsequently introduced. In other words, both the thread former and the corresponding implant do not have a step-shaped taper corresponding to the drill, but rather have a uniformly conically tapering course, the cone angle typically being on the order of 4 ° to 5 ° and conveniently located somewhere in the Range can be between 2 ° and 10 °.

The bore is thus made such that the widened portion has an enlarged portion from the bone surface directed to the row of teeth, initially over a depth of typically between 1, 5 and 3 mm, and subsequently at a depth which may comprise a further 5-15 mm. is rejuvenated accordingly. Now, a thread former is introduced, which is equipped with a similar cone angle as the drill, but has no stepped taper or extension, however, which is dimensioned so that the diameter of the enlarged portion after screwing into the bore by about 5% is increased, so the diameter of the deeper hole section is widened by an amount between 15 and 30%. The thread former is deliberately not designed as a tap, but, as the name implies, as a tool forming the thread, namely by plastic deformation of the bone material. Consequently, the thread former also has no cutting lugs or the like, as otherwise known from thread cutting tools, but only a corresponding thread, which preferably has low friction relative to the bone material and as a screw is screwed into the pilot hole, wherein the bone material through the corresponding threads pushed outward and compressed. The basic conical shape distributes the thread forming process over several turns of the thread former. Because of the mentioned differences in diameter, the area of the cancellous bone is deformed and compressed much more strongly than the area of the corticalis. This also corresponds to the very different strengths of corticalis and cancellous bone.

A further aspect of the invention is a thread former for producing a thread in a bore of a jawbone for anchoring dental implants, which is fashioned such that the thread former has a first lower conical section with an external thread and an adjoining second upper cylindrical section having an external thread, and the thread in the second section has the same pitch as the thread in the first section.

This thread former according to the invention is particularly suitable for the preparation of the cavity for insertion of a previously described dental implant. In this case, the thread of the thread former preferably has the larger thread pitch of the first lower portion of the dental implant, so that the thread former produces an internally threaded cavity in which the threads of the lower first portion of the dental implant come to lie exactly congruent and two threads of the upper part of the dental implant come to lie in a thread of the formed thread.

With regard to the thread former, it is alternatively provided according to the invention that the thread former has a first front section and a second section connected thereto, the first section having a length of between 5 and 15 mm and the second section having a length of at least 1.5 mm, and wherein the second portion has a finer thread compared to the first portion. This means that due to the conical shape and the step-shaped taper of the pilot hole, only the front portion initially penetrates into the tapered, deeper portion of the bore and forms the thread therein, this being the area of cancellous bone, which is correspondingly lighter is deformable and is optimally compressed in this way. Depending on the depth of the extended area and the length of the first forward section of the thread former, the second section of the thread former (corresponding to the base section of the drill) does not engage in the extended one until the last 1-2 mm of the helical feed motion of the thread former Area of the bore, it should be noted that both the extended pilot hole and the second portion of the thread former are conical, so that the first threads of the thread provided in the second section may not initially or only slightly with the upper edge of the extended Contact hole. A significant engagement of the upper, second threaded portion of the thread former takes place, depending on the configuration, under certain circumstances only during the last 1 -1, 5 mm of the helical feed movement of the thread former. However, since the thread of the second portion of the thread former is a fine thread and the thread of the first, front portion of the thread forming a coarse thread, which also creates a deeper thread profile, additional tensioning forces can occur during further screwing the thread former, which the Eindre - Making the thread former difficult and to a certain extent also lead to a slight deformation of the coarse thread lying further inside the bone and the fine thread lying in the area of the corticalis. From the- For this reason, it is expedient if the pitches of the coarse and fine threads do not differ, or at least do not differ too much, even if in extreme cases differences in the slopes of up to 50% are possible, if the fine-thread section is relatively late, ie for example engages only in the wall of the extended bore section during the last revolution of the thread former. It is more expedient, however, to reduce the difference in the pitch or to bring the gradients closer together, so that the pitch of the fine thread is at least 60%, preferably 80 or 90%, of the coarse thread. The fine thread may in a preferred variant also identically have the same pitch as the coarse thread, wherein the fine thread property, namely a larger number of threads per axial unit length can be achieved simply by the fact that the fine thread of the upper threaded portion is made more smoothly, so for example zweigängig or dreigängig while the coarse thread of the first, front portion is formed only catchy. Alternatively, the fine thread could be made with a separate thread former or the fine thread portion of the thread former could be rotatable relative to the coarse thread portion to adjust the number of revolutions or threading speed between coarse and fine threads according to the different pitches ,

As a result, even with the same pitch as the coarse thread, the fine thread has a twofold to threefold finer structure and is accordingly also produced with a smaller tread depth, which is also appropriate for the firmer material of the corticalis.

The thread former is preferably made of stainless steel and has a low surface roughness of less than 5 μ. This ensures that when forming the thread only a slight friction occurs and the bone material effectively displaced and is not or only slightly removed. It is even better if the surface roughness is less than 5 μ and particularly preferred is an embodiment in which the stainless steel material of the thread former has a surface roughness of less than 1 μ is polished. In particular, thread formers with electropolished surface and a surface roughness of well below 1 μ, for example, 0.4 μ, have proven to be well suited. The surface roughness is the spatial mean value of the amount of deviations of the surface from an average surface.

The thread of the thread former also has additional special features. Thus, the profile of the coarse thread of the first section and possibly also the profile of the fine thread of the second section is asymmetrically similar to a sawtooth profile, with an upwardly or outwardly facing flank, which forms a smaller angle with the axis of the thread former than the second flank of the Thread profile, which lies on the other side of the thread ridge or on the other side connects to the first edge and which includes a relatively larger angle with the axis of the thread former. The smaller angle of the first flank to the axis of the thread former is of the order of 30 ° and is in any case less than 40 °, while the angle which the second flank encloses with the axis of the thread former is greater than 60 ° and, for example, approximately 70 to 80 ° or even more.

This second flank is directed toward the interior of the jaw bone with a corresponding implant, while the first flank is directed outwards toward the tooth side. As is known, teeth are primarily subjected to pressure during use, in which case the second flanks, which are much stronger for the axis of the drill, absorb this pressure load and transmit it to the jawbone. The lower tensile loads, on the other hand, can be readily absorbed by the flanks enclosing the axis of the thread former and allow a better elastic catching of the occurring forces.

The two extending between two thread ridges flanks of the thread, of which one is employed relative to the axis of the thread stronger than the other, are otherwise connected to each other via a curved portion with alternating radii of curvature. In the preferred embodiment of the invention, the first flank section (associated with FIG the axis of the thread includes the smaller angle) first a radius η, while at the other edge portion a radius r ₂ connects, which is smaller than the radius η. These two radii are in turn connected to each other by a transition radius r ₃ , which is greater than each of the radii r _t , r ₂ and preferably also greater than the sum of these two angles.

In the preferred embodiment of the invention, the radius T ₁ lies in the range between 0.2 and 0.3 mm, the radius r ₂ between 0.1 and 0.2 mm, and the radius r ₃ between 0.35 and 0.7 mm.

The corresponding implant has - apart from special cases to be discussed - a thread identical to the thread, wherein only the axial length of the fine thread section can differ in the implant from the axial length of the corresponding fine thread of the thread former, since the thread forming possibly different deep fine thread according to the respective depth of the enlarged bore portion, while the implant or the threaded portion of the implant is adapted to a specific application in which a certain, fixed depth of the extended bore portion is present, which was then equipped with the fine thread.

The implant is, as already mentioned, formed in two parts and consists of a threaded part which is screwed into the threaded bore produced in the jaw bone, and an anchored thereto, a tooth crown-bearing part. The connection is usually made by a clamping screw which is screwed into an internal thread, which is provided in a recess of the threaded part of the implant. This recess extends from the outwardly facing end face of the threaded portion inwardly and is also stepped, with only the more inner portion has a matching internal thread for the clamping screw while the adjoining and extending to the end face of the threaded portion in contrast something expands is and expediently has a hexagonal or octagonal profile, which acts as anti-rotation. Other cross sections that can act as anti-rotation, of course, come into consideration.

The second, a tooth crown-carrying part of the implant has a corresponding counterpart to the recess formed as a rotation and is inserted into this, wherein additionally a clamping screw extends through a central bore of the second part through into the internal thread of the recess of the threaded part and screwed is, wherein a head of this screw is supported on the surrounding the central bore edge of the second part of the dental implant.

It is inventively provided that the threaded portion and the head of the clamping screw connecting shaft portion has a smaller diameter than corresponds to the core of the thread of the clamping screw. Usually, a non-threaded shank portion of a tightening screw has a diameter that approximately corresponds to the outer diameter of the threaded portion, namely, because corresponding threads are usually inserted into a cylindrical shank, i. be pressed or screwed. According to the invention, however, it is provided that the shaft of the clamping screw has a 10-30% smaller diameter than corresponds to the core of the thread. Specifically, in a preferred embodiment of the invention, a clamping screw with an M2 thread is used, in which the diameter of the shaft connecting the threaded portion and the head is only about 1.6 mm.

In addition, the transitions of this shaft to both the head and the threaded portion of the clamping screw has a radius of at least 0.1 mm, preferably of about 0.2 mm. It has been shown that a clamping screw formed in this way is better secured against unintentional loosening and holds the two parts of the implant together permanently securely.

It is understood that this particular form of the clamping screw, as just described, generally used in all two-piece implants regardless of whether they have the special thread form of the present invention.

As already mentioned, it is preferable for the thread former if the fine thread section is designed to be more continuous, but has the same thread pitch as the coarse thread section, which is designed to be single or has fewer threads than the fine thread section. Deviating from the otherwise identical design of the thread of the thread former and the threaded part of the implant, however, in the threaded part of the implant, the fine thread may also have a smaller pitch than the coarse thread. Due to the conical shape of the threaded hole, the fine thread section of the threaded part of the implant is only relatively late, e.g. only during the last millimeter of axial movement, with the fine thread engaged. In the thread former, however, the fine thread sooner engages the bore wall and, depending on the selected cone angle and the tread depth of the thread, already engages the upper edge of the enlarged bore. Therefore, to form the thread fine thread and coarse thread should have the same slope, otherwise one or both threads would be too deformed and possibly completely destroyed. However, since the threaded part of the implant with the finished threaded bore only relatively late engages the corresponding fine threaded portion of the threaded bore, at least in the region of the fine thread portion, a difference in the thread pitches in the threaded portion of the implant during clamping of the implant to a tension between Upper and lower threaded portion, which can improve the fit of the implant in the threaded hole and may also accelerate the healing process, because the stressed bone material tends more quickly to adapt to the tension conditions and relocate.

However, the difference between the pitches of the fine thread and the coarse thread should be sufficiently small so as not to completely deform or destroy the previously made threads. Further advantages, features and possible applications of the present invention will become apparent from the following description of a preferred embodiment and the associated figures. Show it:

1 shows a two-part dental implant in a longitudinal section with a clamping screw connecting the two parts,

FIG. 2 shows an external view of the threaded part 10 of the implant according to FIG

1 ,

FIG. 3 shows the threaded part 10 of the implant according to FIG. 1, partly in axial section,

FIG. 4 shows the thread of the threaded part 10 corresponding to the circle 4 in FIG. 2,

FIG. 5 shows an end view of the threaded part 10 from above,

FIG. 6 shows a side view of a clamping screw,

7 shows the view of a clamping screw from above,

8a-c show a view of a second embodiment of a dental implant according to the invention in side view (a), longitudinally cut side view (b) and top view from above (c),

Figure 9a-c is a view of a third embodiment of a dental implant according to the invention in side view (a), longitudinal sectional side view (b) and top view from above (c), and

10 shows a section of the thread of the dental implant or thread former in the lower section.

FIG. 1 shows a two-part implant according to the invention with a threaded part 10, a tooth crown-carrying part 20 and a clamping screw 30 connecting the two parts 10, 20. The second tooth crown-carrying part 20 of the implant is hollow throughout and has a central bore , the tapering stepwise in the lower region, wherein the lower end of the second part 20 terminates in a securing pin 31, which has an octagonal outer profile and sits in a corresponding, octagonal receptacle 4 of the threaded part 10. At the upper end, the second part 20 still has a dental crown holder 32. The threaded part 10 will be described later in detail. As already mentioned, the part 10 has a central blind bore, which is widened in the upper region (axial length e) ¹ to an octagonal receiving profile 4 for the securing pin 31 and which is provided with an internal thread 11 in the lower section (axial length c) , In the preferred embodiment, this is a metric thread with a nominal diameter of 2 mm. The screw 30 consists of a screw head 31, a shaft 32 and a threaded portion 33. The screw 30, as well as the threaded portion 10, in connection with the other figures will be described in detail.

FIG. 2 shows only the threaded part 10 in a side view. As you can see, the threaded portion 10 has a slightly conical shape, wherein the cone angle of the corresponding enveloping conical surface, ie the opening angle of diametrically opposite sides of the cone, about 5 °, but could also be chosen slightly smaller or larger. The threaded portion, generally designated 10, consists of a lower threaded portion 1 which extends over an axial length a, including a threadless tip portion 8, and an upper fine thread portion 2 having an axial length b (see Figure 3). In the implanted state, the upper edge of the fine thread section 2 terminates approximately flush with the surface of a jaw bone, while the section 1 is completely received in the interior of the jaw bone and extends in particular in the cancellous bone of the jaw bone, while the fine thread section 2 substantially to the denser and harder outer wall of the bone, the so-called corticalis, is limited. The lower threaded portion 1 has a coarse thread with a thread height H, while the upper fine thread section 2 has only one thread height h, however, is designed as a double-threaded thread, with the result that in each case a gear has twice the value of the pitch h, the axial Distance between two successive threads shows, however, parallel to each other in the Fine thread section rotate. Even if the difference between the distance h of adjacent threads of the fine thread in the region 2 and the thread height H of the coarse thread portion 1 is shown relatively large in the figures, the value h is still approximately half of the value H in the case of a double-threaded thread the pitch of the fine thread can be approximated in the section 1 despite the greater number of individual threads per axial unit length of the pitch of the coarse thread. The inner threaded bore 3 of the threaded part 10, which can be seen better in the axial section according to FIG. 3, is indicated in FIG. 2 by dashed lines. As can be seen in Figure 3, the lower tip 8 of the threaded part 10, which is formed as a cone with a cone angle of about 90 °, an axial length s, which is typically of the order of 1 mm or slightly smaller.

The terms "top" and "bottom" are used in the context of the present description according to the orientation of the parts in the figures. It is understood, however, that the position of these parts in the jaw of a patient of course deviates from this orientation, it being further clear that the

Tip 8 is always located inside the jaw bone, while the upper edge of the fine thread section 2 substantially with the surface of the jaw bone, in which the corresponding bore is introduced, completes.

In the illustration according to FIG. 3, the blind hole, consisting of the octagon receiver 4 and the female threaded portion 3, which is provided for the connection to the upper part 20 of the implant, which carries a corresponding tooth crown, can be seen more precisely. As you can see, the introduced centrally into the upper portion of the threaded portion 10 hole in the upper part is extended to an octagonal profile, the octagonal shape of the profile is best seen in the plan view of Figure 5. This octagonal cavity 4 in the profile serves as a receptacle and against rotation for a corresponding octagonal pin 21 of the upper implant part 20. This receiving bore tapers in the further course downwards to a threaded bore 3 which in the preferred embodiment has an M2 internal thread - has. The cavity 4 with the octagonal profile has an axial length e and the adjoining cavity, which has the internal thread 3, has an axial length c. The length e is typically in the order of 1, 5-2 mm and c in the order of 2-4 mm.

FIG. 4 shows a section of the thread profile of the external thread of the lower section 1 of the threaded part 10. As can be seen, the thread has a sawtooth profile with a first flank 6, which is flatter towards the axis, and a second flank 7, which is more inclined towards the axis has the edge 7 down, ie towards the interior of the jawbone, while the flank 6 points upwards towards the row of teeth.

As can also be seen, the two flanks 6 and 7 are interconnected by a curved surface with three different radii, the relationship is r ₂ <T ₁ <r ₃ and wherein the portion with the radius T ₁ adjoins the flank 6, the surface with the radius r ₂ connects to the flank 7 and the surface with the radius r ₃ connects the surfaces curved with π and r ₂ .

Figure 5 is a top plan view of threaded portion 10 of the implant, so that you can see relatively well in this view, the internal thread 3 or its inner diameter and the octagonal profile 4. The octagonal profile typically has a clear dimension of about 2.5 mm, with the overall diameter D of the upper portion 2 of the threaded portion 10 typically being between 3.5 and 4.5 mm.

Figures 5 and 6 show the clamping screw 3 used for the connection of the two implant parts. The clamping screw 3 has, as already mentioned, a head 31, which is supported on a shoulder inside the bore of the upper implant part 20, which is at the transition is formed from the upper shaft portion of the implant part 20 to the plug 21 acting as anti-rotation. The clamping screw also has a lower threaded portion 33, and a threaded portion 33 and the head 31 connecting shaft 32. The screw 30 has a length which is typically in one Range of about 7-12 mm, of which a good quarter on the head 31 and the threaded portion 33 accounts and almost half of the shaft 32. The shaft 32 is formed with a significantly smaller diameter than the threaded portion 33, wherein the diameter di the shaft is only about two-thirds of the nominal diameter d _{2 of} the threaded portion 32. The head 31 in turn has an even larger diameter d ₃ , which is again 10-15% greater than the diameter of the threaded portion 33, which is necessary only because the threaded portion 30 through the central bore of the upper implant part and into the threaded bore of the lower implant part 10 must be introduced while the head must be supported simultaneously on the edge of the step-like tapered bore of the upper implant part 20.

It has also proved to be particularly favorable when the shank 32 transitions over a radius R into the head 31 or the threaded portion 33, wherein this radius R should be at least 0.1 mm and preferably about 0.2 mm.

The head 31 is also provided with a hexagon socket 34 into which a suitable hex key can be inserted to rotate the screw. The hexagon socket 34 is clearly visible especially in the plan view of the screw head from above according to FIG.

In the preferred embodiment, the threaded portion 30 has an M2 thread, with the shank 32 only having a diameter in the range between 1.3 and 1.6 mm. This is between 30 and 20% below the nominal diameter of the threaded portion 33.

The implant according to the invention proves to be more durable and better resilient than previous implants and has relatively short healing times. It is understood, however, that the foregoing description has given only a preferred embodiment, while the specific embodiments may be varied within the scope of the independent claims.

With reference to FIGS. 8a-c, a second embodiment of the dental implant according to the invention has a lower section 110, in which the dental implant has an external thread with an anchor for anchoring in the spon- giösen bone adapted thread pitch and thread depth is provided. Both the outer diameter and the core diameter of this external thread tapers conically towards the tip 109 of the dental implant. The tip 109 of the dental implant is also conically tapered at a steeper angle and flattened on the underside 108. A recess 107, which extends from the flat 108 in a lower portion of the threaded portion 1 10, provides a self-tapping effect of the dental implant in this diameter range.

At the top, a transition section 120 adjoins the lower threaded section 110. In this transitional section, the thread pitch and thread depth are continuously reduced to thread pitch and thread depth, which is advantageous for the attachment of denser cancellous bone or cortical bone. This thread pitch and thread depth is continued in a head section 130 of the implant which continues further upwards to the transition region. The thread depth in the head portion of the implant is about one third of the thread depth in the lower threaded portion 110. The thread pitch in the head portion 130 is half the thread pitch in the lower portion 110. Both the core diameter and the outer diameter of the thread in the head portion is in the axial direction kon- constantly, ie the envelope is cylindrical.

Further upwards to the head section 130, a cylindrical, outwardly smooth head section region 140 is arranged on this embodiment of the dental implant, which is bounded at the top by an axially aligned abutment surface 152.

In this smooth section, the oral mucosa comes to rest after implantation, whereby, depending on skin thickness and pocket depth, parts of it can also lie in the region of the thread in the head section.

Subsequent to this smooth cylindrical portion, a tool engagement is integrally formed, which is provided by an external hex 150. The edges 151 of the external hexagon are tapered upwards. new, so that the application of a tool during the implantation process is facilitated.

At the upper end, the implant terminates with a head termination surface 154 into which a blind bore is made along the central axis of the implant. The blind hole comprises, starting from the head end surface 154 a chamfer 161, to which a cylindrical portion 162 connects.

An internal thread 163 with a corresponding tool outlet 164 adjoins the cylindrical section 162.

The internal thread 163 serves to screw in a screw of the type described above, in order to connect the dental implant according to the figures 8a-c with a tooth structure part, thereby forming a two-part dental implant.

In this case, the external hexagon 150 serves, in cooperation with an internal hexagon on the tooth structure, to prevent rotation between the mounting part and the implant part.

Referring to Figures 9a-c, a third embodiment of the dental implant according to the invention is shown. The dental implant has a tip 209, a lower section 210, a transition section 220 and a head section 230 followed by a smooth head section 240, which correspond to the corresponding sections 109-140 of the dental implant according to FIGS. 8a-c.

However, unlike the one according to FIGS. 8a-c, the dental implant according to FIGS. 9a-c does not have any external hexagon as tool engagement and anti-twist protection. Instead, the dental implant terminates immediately above the cylindrical smooth portion 240 with a head termination and abutment surface 252 into which a frusto-conical bore 261 is inserted.

The frusto-conical bore 261 opens into a hexagon socket 250 which is formed in the implant. Below this hexagon socket 250 is a cylindrical rischer space 253 arranged whose outer diameter is greater than the outer diameter of the hexagon socket 250. The cylindrical space 253 serves as a tool outlet for the manufacture of the hexagon socket and is provided to reduce the notch effect with rounded corners.

Connected to the cylindrical space 253 downwards is an internal thread 263 with a tool outlet 264, which is analogous to the internal thread 163 and tool outlet 164 and also serves to attach a tooth structure to the dental implant according to FIGS. 9a-c, in order in this way To provide two-piece implant.

Figure 10 shows a section of the lower threaded portion of the thread former or dental implant in a sectional view and illustrates the thread geometry of the invention. As a vertical, dotted line the drill axis or the longitudinal axis of the thread former or the dental implant is located. As can be seen, the flank surface of the thread pointing obliquely upwards extends downwards in a straight thread flank section which assumes an angle α 1 to the longitudinal axis of the thread former or dental implant or drill. This angle is preferably less than 40 ° and is in particular between 25 and 30 °.

In the same way, the flank surface of the thread pointing downwards outwards extends in a straight surface section which lies at an angle α 2 to the longitudinal axis of the drill, thread former or dental implant. This angle .alpha.2 is opposite to the angle .alpha.1, in the illustration according to FIG. 10 .alpha.2 is open at the bottom and .alpha.1 is open at the top. The angle α2 is in particular greater than 60 ° and is preferably about 70 °.

For purposes of the original disclosure, it is to be understood that all such features as will become apparent to those skilled in the art from the present description, drawings, and claims, even though they have been specifically described only in connection with certain further features, both individually and separately any combinations with other of the features or feature groups disclosed herein are combinable, as far as this was not expressly excluded or technical conditions make such combinations impossible or pointless. On the comprehensive, explicit representation of all conceivable combinations of features is omitted here only for the sake of brevity and readability of the description.

Claims

1. Dental implant for anchoring in a hole in a jawbone, with a. a first lower portion for anchoring the dental implant in the cancellous area of the jawbone, b. a second, upper portion for attaching the dental implant to the cortical top region of the jaw bone and the mucosal tissue covering the jaw bone, characterized in that - the first lower portion is provided with an external thread having a first pitch,

- The second upper portion is provided with an external thread having a second pitch which is smaller than the first pitch, and - between the first and second portion, a transition portion is arranged, in which a thread is formed, the geometry of which is adjacent to the first Section from the geometry of the first thread continuously for connection to the second section in the geometry of the thread of the second section changes.

2. Dental implant according to claim 1, characterized in that the first lower portion is conically tapered downwards.

3. Dental implant according to claim 2, characterized in that the conical taper is achieved by the core diameter of the thread tapers conically from top to bottom and the outer diameter of the thread is cylindrical.

4. Dental implant according to claim 2, characterized in that the conical taper is achieved by the outer diameter of the thread tapers conically from top to bottom and the core diameter is cylindrical.

5. Dental implant according to claim 2, characterized in that the conical taper is achieved by the outer diameter and the core diameter of the thread tapers conically from top to bottom.

6. Dental implant according to one of the preceding claims, characterized in that the core diameter and / or the outer diameter of the thread in the second upper portion is cylindrical.

7. Drill for making a hole in a jaw bone for anchoring a dental implant, consisting of a shank and a conical cutting part, characterized in that the drill is designed as a stepped drill by the cutting part of a first koni see front section and an adjoining also has a conical base section, wherein the drill diameter at the transition from the front section to the base section increases stepwise by an amount that is between 10% and 25% of the diameter of the front section immediately before the transition to the base section.

8. Drill according to claim 7, characterized in that the front portion has a length between 5 and 15 mm and the base portion has a length of at least 1, 5 mm.

9. Drill according to one of claims 7 or 8, characterized in that the cone angle of the drill for both the front portion and the base portion between 2 ° and 10 ° and preferably for both about 5 °.

10. Thread former for producing a thread in a bore of a jaw bone for anchoring dental implants, characterized in that the thread former has a first lower conical portion with an external thread and an adjoining second upper cylindrical portion with an external thread, wherein the thread in the second section has the same pitch as the thread in the first section.

11. A thread former for producing a thread in a bore of a jawbone for anchoring dental implants, wherein the bore is formed as a total conical stepped bore, which tapers from a conical, adjoining the opening of the bore initial portion to an adjoining end portion, characterized that the thread former has a first front

Section and an adjoining second section, wherein the first section has a length between 5 and 15 mm and the second section has a length of at least 1, 5 mm, and wherein the second section has a compared to the first section finer thread.

12. Thread former according to claim 11, characterized in that the thread is catchy in the first section and more in the second section, in particular two or three thread turns.

13. Drilling tool or thread former according to claim 10 or 12, characterized in that the pitch of the thread in the second section is between 50% and 100% of the pitch of the thread in the first section.

14. Thread former according to one of claims 11 to 13, characterized in that the first portion and the second portion have a common conical envelope surface.

15. Thread former according to one of claims 11 to 14, characterized in that the cone angle of the first and the second

Section between 2 ° and 10 °, in particular for both at about 5 °.

A thread former according to any one of claims 10 to 15, characterized in that the thread of the first section is an a-symmetrical sawtooth profile with an upwardly facing flank surface which includes a significantly smaller angle with the axis of the drill than one on the other side a thread ridge adjacent, downwardly facing flank surface.

17. A drill or thread former according to claim 16, characterized in that the angle (σ1) of the upwardly facing flank surface to the drill axis is less than 40 °, in particular between 25 and 30 °, while the angle (σ2) of the downwardly facing flank surface to the axis of the drill more than 60 °, in particular about 70 °.

18. Drill or thread former according to one of claims 16 or 17, characterized in that a rounded transition is provided between adjacent flank surfaces with a curvature radius r1 adjoining the first flank surface, a second curvature radius r2 adjoining the second flank surface being smaller as the first radius r1 and a transition therebetween having a radius r3 greater than each of the two radii r1 and r2 and which is preferably greater than the sum r1 + r2.

19. Thread former according to claim 18, characterized in that the angle ιi between 0.2 and 0.3 mm, the angle r2 between 0.1 and 0.2 mm and the angle r3 is between 0.35 and 0.7 mm.

20. Thread former according to one of claims 10 to 19, characterized in that the thread former made of stainless steel with a surface roughness of less than 5 μ, in particular of less than 3 μ.

21. Thread former according to claim 20, characterized in that the surface roughness is less than 1 μ.

22. Two-part dental implant, with a first, in a jaw bone screwed threaded portion (10) and a second, attached thereto

Part (20) for holding a tooth crown, characterized in that the threaded part (10) has a continuously interlocking or two-stage thread according to the thread former according to one of claims 4 to 15.

23. Dental implant according to claim 22 or one of claims 1-6, characterized in that the outside of the jaw bore facing portion of the threaded portion has a step-shaped recess (34), wherein a deeper-reaching recess of smaller diameter with an internal thread (3) is and subsequent to the end of the threaded portion, further portion of the recess with an anti-rotation, preferably in the form of a hexagonal or octagonal profile (4) is equipped.

24. Dental implant according to one of claims 22 or 23 or one of claims 1-6, characterized in that the tooth crown-carrying portion of the implant by means of a clamping screw (3) on the threaded portion (10) Be which is screwed into the threaded portion (3) of the recess of the threaded portion (10) and secured with a screw head (31) on the second part (20) of the dental implant, wherein threaded portion (33) and head (31) of the screw (3) are interconnected by a tapered shank (32) whose diameter is smaller than the core diameter of the threaded portion (33) of the screw.

25. Dental implant according to claim 24, characterized in that the core of the threaded part of the screw corresponds to a metric M2 thread, while the shaft has a diameter of 1.6 mm.

26. Dental implant according to one of claims 24 or 25, characterized in that the transition of the screw shaft (32) both to the screw head (31) and to the threaded portion (33) over a radius (R), which is at least 0.1 mm, preferably about 0.2 mm.