Ceramic dental implant

Abstract

This invention relates to a ceramic dental implant (100) for implantation into the jawbone, the implant (100) extending from a apex (103) to a coronal end (102). The implant (100) has a blind hole (104) opening toward the coronal end (102) of the implant and extending toward the apex (103) along a central longitudinal axis LA. The blind hole (104) includes a threaded section (107) having a base surface (108) from which a thread (109) projects radially inward, the base surface (108) defining a maximum radius R of the thread (109) measured from the central longitudinal axis LA. max The thread (109) has a crown facet (112) and a top facet (114), which are connected at their radially inner ends by a crest (116), which defines the minimum radius R of the thread (109) as measured from the central longitudinal axis LA. min The thread (109) extends helically along the axial length of the thread section (107) and has a depth defined by the radius difference between the base surface (108) and the crest (116). The thread section (107) includes a main portion (115) in which the maximum radius R of the thread (109) is... max The length of the portion (115) remains constant; and there is a tapering portion (117) adjacent to the main portion (115) at the top, in which the base surface (108) extends in the upward direction from the maximum radius R of the thread (109) in the main portion (115). max The minimum radius R of the thread 109, which tapers radially inward to the tip of the tapered portion (117), is... min The tapered portion (117) extends in an axial length greater than the thread pitch to form a tapered thread (119) with a gradually decreasing thread depth, the tapered thread (119) extending more than one turn of the thread.

Description

Technical Field

[0001] This invention relates to dental implants made of ceramic material and having holes with internal threads. Background Technology

[0002] Dental implants are used to replace one or more teeth in a patient's mouth. They typically consist of an anchor portion that is inserted into the patient's jawbone, and an abutment portion that extends through the gums and into the patient's mouth, where it provides core support for the final prosthesis (e.g., crown, bridge, complete denture).

[0003] The anchoring portion and the abutment portion can be supplied as a single integral piece, but more commonly they are supplied as separate components connected together by screwing, joining, compression fitting, etc. Such implant systems are often referred to as "two-part" or "two-piece" implants, in which the anchoring portion is usually referred to separately as the "implant" or "fixation device," and the abutment portion is referred to as the "abutment" or "post."

[0004] The anchoring portion of a two-piece implant is typically either fully embedded in the bone (i.e., embedded to the height of the alveolar ridge) or protrudes a few millimeters into the soft tissue from the alveolar ridge. Anchoring portions designed for full insertion into the bone are generally referred to as "bone-level" implants, while those designed to extend into the soft tissue are generally referred to as "tissue-level" implants. The abutment can be attached to the anchoring portion directly or indirectly via one of a variety of known means. Most commonly, the abutment is bonded to the anchoring portion or threaded to it. In the latter case, it is common for the anchoring portion to include a longitudinally extending blind hole with internal threads. The abutment or another component can then be fastened to the anchoring portion by a screw that tightens into the internal threads of the anchoring portion.

[0005] One-piece dental implants (where the anchor portion and abutment portion are integrally formed) may also include blind holes with internal threads to allow other components of the dental system (e.g., prostheses, healing caps, etc.) to be threadedly attached to the implant.

[0006] This invention can be applied to both one-piece and two-piece implant systems. Therefore, for the remainder of this specification, the reference to "implant" refers to a component of a system intended for at least partial insertion into and osseointegration with the bone, regardless of whether the component includes a one-piece abutment.

[0007] Most dental implants used today are made of titanium or its alloys. Such materials have the strength to withstand the chewing forces the implant will experience throughout its lifespan, and sufficient biocompatibility to achieve osseointegration.

[0008] However, from an aesthetic point of view, titanium implants have the following disadvantages: they are dark in color and therefore do not match the color of natural teeth.

[0009] During the lifespan of an implant, the gums and jawbone often recede. As a result, the dental implant becomes visible and, due to its dark color, is also visually perceptible.

[0010] In contrast, ceramic materials more closely match the color of natural teeth. Furthermore, a growing number of consumers desire to reduce or eliminate the use of metal in implants placed in the body. Therefore, efforts have been made to provide dental implants made of ceramic materials such as zirconia and alumina.

[0011] However, ceramics are a more brittle and fracture-prone material compared to metals. Therefore, there is a risk that parts of the implant system can become damaged when, for example, anti-rotation elements and threads are milled into the ceramic material during manufacturing. Additionally, during use, material fracture can occur in areas where load peaks occur, such as in the contact area between the abutment or other components and the implant.

[0012] In particular, fixing the abutment or other components to the implant with screws can cause stress concentration at the internal threads of the implant and lead to crack formation.

[0013] To take into account the different material properties of ceramics compared to metals, the optimal design of ceramic implant systems can differ from that of metal systems.

[0014] US 6,280,193 B1 describes a ceramic dental implant formed by injection molding and including internal threads. The internal threads have rounded apexes and a hollow portion to ensure greater stability of the threaded connection.

[0015] EP 2 735 279 A1 illustrates a ceramic dental implant with a long blind hole, wherein the thread is located in the lower half of the hole. It is said that the increased length of the blind hole better distributes stress onto the implant body. Summary of the Invention

[0016] In view of the problems specifically related to implants made of ceramics mentioned above, at least the preferred embodiments of the present invention aim to provide a ceramic implant with internal threads that is less prone to breakage.

[0017] This objective is achieved through at least preferred embodiments of the invention described in this disclosure. Other preferred embodiments are also described in this disclosure.

[0018] According to a first aspect, the present invention provides a ceramic dental implant for implantation into the jawbone, the implant extending from the apex to the coronal end. The implant has a blind aperture opening toward the coronal end of the implant and extending toward the apex along a central longitudinal axis. The blind aperture includes a threaded section having an abutment surface from which a thread projects radially inward, the abutment surface defining a maximum radius of the thread measured from the central longitudinal axis. The thread has a coronal lateral surface and a apical lateral surface, these lateral surfaces being connected at their radially inner ends by a tooth crest, the tooth crest defining a minimum radius of the thread measured from the central longitudinal axis. The thread extends helically along the axial length of the threaded section and has a depth defined by the difference in radius between the abutment surface and the tooth crest. The threaded section includes: a main portion in which the maximum radius of the thread remains constant along the length of the main portion; and a tapered portion adjacent to the main portion at an upward direction in which the base surface radially tapers inward from the maximum radius of the thread in the main portion to the minimum radius of the thread at the tip of the tapered portion, the tapered portion extending in an axial length greater than the thread pitch to form a tapered thread with a gradually decreasing thread depth, the tapered thread extending more than one turn of the thread.

[0019] In conventional dental terminology, the "apex" refers to the direction towards the bone, and the "crown" refers to the direction towards the tooth. Therefore, the apex of a component is the end that points towards or enters the jawbone during use, and the crown is the end that points towards or enters the oral cavity.

[0020] As used throughout this specification, the terms "crown lateral surface" and "top lateral surface" refer to the surface of the thread extending from the abutment surface toward the central longitudinal axis of the blind hole. The top lateral surface is defined as the lateral surface facing the tip of the implant; in other words, the coronal end of this lateral surface is found at the crest of the tooth and the apex of this lateral surface is located at the abutment surface. Conversely, the crown lateral surface is defined as the lateral surface facing the coronal end of the implant; in other words, the coronal end of this lateral surface is located at the abutment surface and the apex of this lateral surface is found at the crest of the tooth.

[0021] As used throughout this specification, the term "pitch" refers to the axial distance between the crests of two adjacent threads, or in other words, the axial length of a complete turn of the thread.

[0022] According to the invention, the threaded section includes a tapered portion in which the base surface tapers radially inward in a topward direction. Therefore, the maximum radius of the thread in the tapered portion decreases in the topward direction; from the maximum radius of the thread in the main portion (i.e., the radius of the base surface in the main portion) to the minimum radius of the thread at the tip of the tapered portion. As a result, the thread disappears at the tip of the tapered portion because the maximum and minimum thread radii are equal to each other. All thread radii are measured from the central longitudinal axis of the hole. According to the invention, the axial length of the tapered portion is greater than the thread pitch. In this way, the thread depth (i.e., the distance between the base surface and the crest) gradually decreases over more than one turn of the thread, resulting in a smooth tapered runout of the thread.

[0023] This differs from existing implants, where any threaded section of the blind hole typically terminates abruptly in a smooth, conical section with a wide taper angle. The surface of this conical section usually intersects the thread flanks in a manner that causes an acute angle and a thread runout of less than one turn (typically about half a turn). When produced in ceramic implants, this acute angle can lead to cracking and breakage of the implant.

[0024] It has been found that such sharp angles can be avoided by providing a tapered section at the tip of the threaded section of the blind hole. This eliminates stress points in the system and reduces the risk of crack formation within the implant.

[0025] According to the present invention, the maximum radius of the thread is defined by the base surface of the thread section. The minimum radius of the thread is defined by the innermost radial point of the tooth crest, and the depth of the thread at any axial position is given by the difference between the radius of the base surface and the radius of the tooth crest at that position.

[0026] In a preferred embodiment, the minimum radius of the thread is constant at least along the entire longitudinal length of the main portion of the thread section. Therefore, in such an embodiment, the thread depth and the maximum radius of the thread remain constant within the main portion. This simplifies hole production and provides a uniform force distribution during use.

[0027] Within the tapered section, the minimum radius of the thread may gradually increase in the upward direction in some embodiments, such that the decrease in thread depth within the tapered section is caused by the tapering of both the maximum and minimum radii of the thread. However, it is preferable that the minimum radius of the thread is constant along the entire length of the tapered section. This simplifies the production of the tapered section. Therefore, according to this preferred embodiment, the gradual decrease in thread depth within the tapered section is caused solely by the tapering of the base surface. In a particularly preferred embodiment, the minimum radius of the thread remains constant over the entire length of the thread section.

[0028] In embodiments where the maximum and minimum radii of the thread, and therefore the thread depth, remain constant along the length of the main portion, it is further preferred that the thread profile remains constant along the length of the main portion. "Thread profile" refers to the longitudinal section of the thread, i.e., a section in a two-dimensional plane containing multiple points along the central longitudinal axis of the hole. A uniform profile is easier to manufacture and provides consistent force interaction with the screw.

[0029] However, within the tapered section, the thread profile inevitably changes due to the reduced required thread depth. It is possible to use at least some manufacturing methods (e.g., 3D printing) to maintain the cross-sectional shape of the thread profile while reducing its dimensions along the length of the tapered section. For example, the thread profile in the tapered section can have a triangular shape, but the size of the triangle decreases in the upward direction.

[0030] However, for design simplicity, it is preferable to modify the thread profile within the tapered section by progressively removing areas of the initial thread profile (e.g., the thread profile of the main portion) to change the cross-sectional shape of the thread profile along the length of the tapered section. For example, within the tapered section, the thread profile can be modified by progressively removing the radially inward portion of the profile (i.e., changing the tooth crest shape) along the length of the tapered section. Returning to the triangle example above, in this embodiment, the apex of the triangle (located at the tooth crest) will be progressively removed along the length of the tapered section. This design gives the visual impression that the thread tooth crest is progressively "shaved off" until the thread is completely ground away.

[0031] However, preferably, within the tapered section, the thread profile is modified by the following steps: gradually removing the radially outer portion of the profile, i.e., changing the transition from the base surface to the thread sidewall, this area of ​​the thread is referred to as the thread root. Using the triangle example above, in this embodiment, the base of the triangle (where the base contactes the base surface) is gradually removed along the length of the tapered section. This design gives the visual impression that the thread is "submerged" beneath the tapered base surface.

[0032] It is also possible to combine these methods so that within the tapered section, the area of ​​the thread profile is gradually removed at both the radially outer and radially inner portions, making the thread appear to be both sheared off from the crest and simultaneously submerged from the root. However, since the objective of this invention is to provide a gradual reduction in thread depth, and for reasons of design simplicity, it is generally preferred to gradually remove only the inner or outer portions of the thread profile within the tapered section. In this way, either the thread root remains constant while the crest shape changes, or the thread crest remains constant while the thread root shape changes.

[0033] All of the above design possibilities for changing the thread profile can be used in embodiments where the minimum radius of the thread in the tapered portion remains constant or increases in the upward direction.

[0034] As previously discussed, in a preferred embodiment, the minimum radius of the thread remains constant within the tapered portion. In a particularly preferred embodiment, within the tapered portion, the thread profile remains constant relative to the base surface of the main portion, such that within the tapered portion, the thread is gradually submerged by the tapered base surface. This embodiment is an example of gradually removing the radially outer portion of the thread profile to achieve a tapered thread.

[0035] In a particularly preferred embodiment, the thread profile remains constant along the length of the main portion, and according to one of the design concepts discussed above, the profile is gradually removed in the tapering portion.

[0036] According to the invention, the tapered thread formed within the tapered portion extends at least one turn of the thread. In other words, the gradual decrease in thread depth occurs in a section of the thread extending more than 360° around the central longitudinal axis. This is achieved by providing a tapered portion with an axial length greater than the thread pitch. Preferably, the tapered thread extends more than two turns, more preferably between two and eight turns, and most preferably between four and six turns.

[0037] Preferably, the threads have a pitch of 0.2 to 0.5 mm.

[0038] Preferably, the tapered portion extends over at least one-quarter of the axial length of the threaded section, more preferably over at least one-third of the axial length of the threaded section.

[0039] As mentioned above, according to the present invention, the base surface of the threaded section defines the maximum radius of the thread. In other words, the base surface is the surface containing all points along the axial length of the threaded section where the thread has the maximum radius. Extrapolating these points gives a virtual surface defining the shape of the base surface. In the main portion of the threaded section, the maximum radius of the thread, and therefore the radius of the base surface, remains constant. Therefore, the shape of the base surface along the length of the main portion is cylindrical.

[0040] According to the invention, within the tapered portion, the tapered thread is formed at least partially by radially tapering the base surface in the upward direction. The base surface within the tapered portion can tapere in a curved manner, i.e., the base surface can tapere radially, such that the shape formed by the base surface is, for example, spherical or oval. However, preferably, within the tapered portion, the base surface taperes radially inward at a cone angle. Thus, in such an embodiment, the shape formed by the base surface is conical. This simplifies the design of the tapered portion. As used in the context of this invention, the term "cone angle" refers to the angle formed by the surface in question relative to the central longitudinal axis of the hole. Within the tapered portion, for a given pitch, the smaller the cone angle of the base surface, the larger the number of thread turns. A smaller cone angle results in a more gradual inward tapering of the base surface, and therefore a more gradual decrease in the thread depth.

[0041] The cone angle of the base surface may not be constant along the length of the tapered portion. For example, the tapered portion may include: a first section in which the base surface has a first cone angle; and a second apex section in which the base surface has a second cone angle greater than the first cone angle. However, preferably, the cone angle of the base surface within the tapered portion is constant over the entire length of the tapered portion. This is advantageous both from a manufacturing and force distribution perspective.

[0042] In a particularly preferred embodiment, the taper angle of the base surface within the tapered portion is less than 20°, preferably less than 10°, and most preferably approximately 8°. These angles provide a sufficiently gradual taper to provide the desired smooth thread runout.

[0043] Additionally or alternatively, the taper angle of the base surface within the tapered portion is preferably smaller than the taper angle of the crown side of the thread. The taper angles of the top side and the crown side can be the same or different. Making the taper angle of the base surface smaller than the taper angle of the crown side is highly beneficial in ensuring that no acute angles are formed at the intersections of these sides and the base surface.

[0044] Alternatively or preferably, within the tapering portion, the angle formed between the base surface and both the top and crown sides is an obtuse angle, i.e., greater than 90°. This prevents these angles from becoming sharp, which would create stress points.

[0045] All of the above-mentioned preferred configurations of the tapered section, individually and / or in combination, help to generate the gradually tapering runout of the thread, thereby preventing or reducing stress concentration.

[0046] As previously mentioned, according to the present invention, the threaded section includes a thread that projects radially inward from the base surface, the thread including a crown side and a top side, which are connected by a tooth crest at their radially inner ends.

[0047] Preferably, the thread has a thread angle of 50° to 70°. The term "thread angle" here refers to the angle enclosed by the two sides at the crest of the thread.

[0048] Preferably, along the length of the main portion of the threaded section, there is a curved transition between these sides of the thread and the base surface. Such a curved transition helps prevent sharp angles within the hole and reduces the likelihood of stress concentration and crack formation. In a particularly preferred embodiment, when viewed in longitudinal section, there is a fully curved transition at their radially outer ends between adjacent top and crown sides. As discussed earlier, "longitudinal section" means a section taken in a two-dimensional plane containing the central longitudinal axis of the blind hole (i.e., multiple points along this axis). Such a fully curved transition at the root of the thread reduces the tension between the internal threads of the implant and the external threads of the auxiliary portion or fixing screw. In such an embodiment, the base surface is tangent to the curved transition. The curved transition can be oval or elliptical, but preferably, when viewed in longitudinal section, the transition has an arc shape.

[0049] Within the tapered section, the transition between the base surface and the top and crown flanks can also be curved, as described above regarding the main section. This is especially true when the thread profile remains constant at the thread root while the radially inward portion of the thread is gradually removed, or when the cross-sectional shape of the thread profile remains constant while its dimensions decrease. However, as discussed above, in a preferred embodiment, the thread profile within the tapered section is modified by gradually removing the radially outward portion of the thread profile. In such an embodiment, any curved transition between the base surface and the thread flanks within the tapered section is preferably kept to a minimum, i.e., according to manufacturing tolerances.

[0050] At least along the length of the main portion, the profile of the thread crest (i.e., the longitudinal section) can be any known shape, such as flat, pointed, or rounded. To help prevent cracking, it is preferred that the profile of the crest is curved, meaning that there is a fully curved transition between adjacent top and crown surfaces at their radially inner ends. This curved profile can be oval or elliptical. However, in a particularly preferred embodiment of the invention, the crest profile has an arcuate shape. As discussed above, in a preferred embodiment, the thread crest remains constant in the tapered portion, while the radially outer portion of the thread profile is gradually removed. Additionally, in some embodiments, the cross-sectional shape of the thread in the tapered portion remains constant, while the dimensions gradually decrease. In particular, in such embodiments, it is preferred that the longitudinal section of the crest is curved along the entire length of the thread segment, preferably having an arcuate shape.

[0051] Such a curved tooth profile is typically impossible in threads formed by machining; however, it is possible when using methods such as injection molding or 3D printing to manufacture implants.

[0052] Therefore, in a particularly preferred embodiment, the implant is manufactured by injection molding. Ceramic implants can be manufactured by, for example, milling, molding, or 3D printing. Milled or 3D-printed implants can have undercuts constructed in blind holes, which is impossible in molded implants because the mold cannot be released at that point. Those skilled in the art can accurately distinguish between molded implants and milled or 3D-printed implants due to their geometry, mold parting lines, and injection ports.

[0053] Implants manufactured via injection molding are preferred because they are cost-effective for large-volume production, faster to manufacture, and easier to ensure consistency of the produced components. Furthermore, as mentioned above, injection molding allows for the creation of internal threads with curved crowns, in addition to allowing for curved tooth bases, which helps prevent crack formation and implant failure.

[0054] The ceramic implant according to the invention can be manufactured by ceramic injection molding (CIM) method by injecting powdered ceramic material into a forming mold. Thus, the ceramic material is typically provided as a powder, and it contains a binder for better molding or shaping; the binder is preferably removed after shaping by burning it off before sintering. Sintering provides the final shape and hardness. Those skilled in the art are aware that the implant shrinks by a factor during sintering, depending on the material and manufacturing process, but typically by about 25%.

[0055] In particular, HIP (hot isostatic pressing) is preferably used to form implants, not only when manufactured by injection molding but also when using other manufacturing methods. This improves the strength of the implant by increasing the density of the material.

[0056] When implants are formed via injection molding, it is particularly preferred that the radially outer portion of the thread profile is gradually removed within the tapered section to produce the desired reduction in thread depth. This is because such a design is easier to implement in molded blind holes than, for example, removing the radially inner portion of the thread profile. Specifically, it is preferred that the thread profile remains constant relative to the base surface of the main portion within the tapered section, such that the thread is gradually submerged by the tapered base surface within the tapered section.

[0057] According to the invention, the threaded section is located in a blind hole within the implant. Preferably, the apex of the hole is rounded to prevent sharp edges and stress points within the hole. The threaded section can extend along the entire length of the blind hole. However, in a preferred embodiment, it extends only along a portion of the blind hole, resulting in reduced manufacturing costs and complexity. In some embodiments, the threaded section is located only in the lower half (i.e., the top half) of the blind hole. As a result, the length of the connecting screw can be increased, which increases the possible preload of the screw.

[0058] According to the invention, the blind aperture extends along a central longitudinal axis. While the central longitudinal axis of the blind aperture can be offset from the central longitudinal axis of the implant, it is preferred that the blind aperture be coaxial with at least a portion of the implant. For example, some implants are angled such that they include a crown portion extending along a first central longitudinal axis and a top portion extending along a second central longitudinal axis, the first axis and the second axis being angled relative to each other. In such cases, the blind aperture is preferably coaxial with either the crown portion or the top portion of the implant. When coaxial with the top portion of an angled implant, the blind aperture opening will not be located at the crown end surface of the implant, but will open toward the crown end of the implant, allowing the aperture to be accessed from the crown end of the implant.

[0059] However, most implants extend from their apex to the coronal end along a single central longitudinal axis. In such cases, the blind hole not only opens towards the coronal end of the implant, but its opening is also located on the coronal surface of the implant. Preferably, the blind hole is coaxial with the central longitudinal axis of the implant. In other words, preferably, the implant extends from its apex to the coronal end along a central longitudinal axis, and the blind hole opens at the coronal surface of the implant and extends towards the apex along said central longitudinal axis. In this case, the central longitudinal axis of the hole is the same as the central longitudinal axis of the implant.

[0060] In this preferred embodiment, the length of the blind hole, measured longitudinally, is preferably greater than 70%, more preferably greater than 75%, and most preferably at least 80% of the axial length of the implant. This is longer than the holes found in standard titanium implants. The longer the blind hole is relative to the length of the implant, the more uniform the mass distribution of the implant. In standard implants, the tip below the blind hole is typically solid, resulting in a greater mass. This tip mass generates more strain within the implant when the screw is tensioned within the hole. The longer hole reduces the mass at the tip of the implant and thus reduces strain during use. This is particularly advantageous in ceramic implants, given the brittle nature of ceramic materials. Furthermore, reducing the ceramic volume of the implant reduces the likelihood of defects occurring within the ceramic material, especially with respect to 3D printing and injection molding methods.

[0061] These advantages also exist in angled implants, where the hole is located in the top portion of the implant. Therefore, in such embodiments, it is preferable that the length of the blind hole, measured in the longitudinal direction, is preferably greater than 70%, more preferably greater than 75%, and most preferably at least 80% of the axial length of the top portion of the implant.

[0062] As discussed above, it is preferable that the threaded section does not extend over the entire length of the blind hole. Further, it is preferable that the threaded section does not extend to the tip of the hole. Therefore, it is preferable that the blind hole further includes a non-threaded end section extending from the tip of the threaded section to the tip of the hole on the top side of the threaded section. This is particularly advantageous in embodiments where a longer hole length is used (i.e., the length of the blind hole is at least 70% of the length of the implant (or the top portion of an angled implant)). Such a non-threaded end section lengthens the hole while maintaining design simplicity and allowing the same screw length to be used with all implant lengths.

[0063] Because the position of the threaded section within the hole determines the length of the screw that can be used with the implant, the position of this threaded section will generally remain constant relative to the coronal end of the blind hole in implants of different lengths. This allows standard screw lengths to be used with all implant lengths. Therefore, the length of the unthreaded end section will typically vary between implants of different lengths to allow the hole to extend to the desired length of the implant.

[0064] Preferably, the axial length of the non-threaded end section is at least one-third of the length of the tapered portion, and more preferably, the length of the non-threaded end section is between one-third and three times the length of the tapered portion.

[0065] The unthreaded end section can be cylindrical, curved, or conical, or a combination of these shapes. In some embodiments, the shape of the unthreaded end section matches the shape of the outer surface of the implant at its axial position, such that the implant has a substantially constant wall thickness along the length of the unthreaded end section. Therefore, as the outer surface of the implant tapers at its apex, it is preferable that the unthreaded end section of the hole tapers similarly. Alternatively, when the implant is a parallel-wall (cylindrical) implant, it is preferable that the unthreaded end section is cylindrical.

[0066] When implants are manufactured by injection molding, a more or less constant wall thickness improves feed flow during injection molding. Therefore, in such embodiments, it is particularly preferable that any non-threaded end section of the blind hole matches the shape of the outer surface of the implant at its axial position, as discussed above. However, compromises are often necessary to ensure that the tip of the blind hole does not become too narrow. If the mold pin used to form the hole is too thin, it will vibrate during injection molding. Therefore, in some preferred embodiments, the taper angle of the non-threaded end section (relative to the central longitudinal axis of the hole) is equal to or less than the taper angle of the tapered portion of the threaded section (if present). This helps to provide optimal hole length and diameter. Additionally or alternatively, and regardless of whether the tapered portion includes a taper angle, in preferred embodiments, the taper angle of the non-threaded end section is less than 1°, more preferably about 0.5°. This small taper angle prevents the tip of the hole from becoming too thin (even in long hole lengths) while also aiding in demolding. Providing a small taper angle to aid in demolding is beneficial in parallel-walled implants and implants that taper towards the top.

[0067] In a preferred embodiment, the dental implant further includes an anti-rotation element on the coronal side of the threaded section. The anti-rotation element has a non-circular symmetrical cross-section in a plane perpendicular to the central longitudinal axis of the blind hole. This anti-rotation element can be formed within the blind hole or on the outer surface of the implant. The anti-rotation element of the implant can be any known shape, such as oval, polygonal, quincunx, a series of alternating protrusions and recesses, etc. Preferably, the blind hole includes an anti-rotation element on the coronal side of the threaded section.

[0068] When mating auxiliary components (such as abutments, crowns, etc.) with complementary anti-rotation elements are attached to an implant, the axial alignment of the two anti-rotation elements prevents relative rotation of the auxiliary component and the implant about the central longitudinal axis of the hole. When present, the implant's anti-rotation element can also be used as a torque transmission device for a suitable insertion tool to anchor the implant in the jawbone. For this purpose, in a known manner, a correspondingly formed free end of the insertion tool can be releasably engaged with the implant's anti-rotation element to transmit torque to the dental implant.

[0069] The blind hole of the implant is designed to allow auxiliary components (e.g., abutments, healing caps, etc.) to be attached to the implant via a threaded connection to a threaded section. To securely attach the auxiliary component to the implant, the auxiliary component may include external threads designed to engage with the main portion of the threaded section of the blind hole of the implant. Alternatively, the auxiliary component may include a through-hole through which a retaining screw can be inserted, such that the tip of the screw protrudes from the tip of the auxiliary component and engages with the threaded section of the implant hole.

[0070] For example, an abutment with a threaded channel can have a tip designed for insertion into a blind hole of an implant. A retaining screw can be inserted through the threaded channel of the abutment and driven into the internal threads of the implant by means of a tool introduced from above into the threaded channel of the abutment, thereby securely connecting the abutment and the implant. The tip of the abutment may include an anti-rotation element (e.g., a portion having a polygonal cross-section) on its outer surface, which can be axially aligned with a complementary anti-rotation element (e.g., a polygonal portion) disposed in the blind hole to prevent relative rotation of the implant and the abutment.

[0071] Suitable retaining screws can be manufactured from metals (preferably titanium or titanium alloys) in known ways because these materials ensure good stability, biocompatibility, and sterility. An additional advantage of metallic materials is that they possess a degree of elasticity, and the retaining force of the retaining screw increases due to the minimal elastic expansion of the screw along its longitudinal axis as it is screwed in. The tension caused by this expansion then creates a particularly strong connection between the dental implant and the accessory component. In other embodiments, ceramic or polymer screws produced, for example, by milling can be used. This is beneficial in meeting consumer expectations for metal-free dental implants.

[0072] In some preferred embodiments, the blind hole of the implant further includes a threaded section and, where present, a circular, symmetrical, unthreaded section on the coronal side of an anti-rotation element. This unthreaded section can be tapered or non-tapered in the longitudinal direction and serves to provide a deeper and therefore more stable connection between the implant and the auxiliary component.

[0073] Preferably, the coronal-side circular symmetrical unthreaded segment is cylindrical. However, in other embodiments, the coronal-side circular symmetrical unthreaded segment may be conical, and helps to create a good seal between the implant and the accessory component, such as a Morse taper. In an alternative preferred embodiment, the coronal-side circular symmetrical unthreaded segment comprises multiple conical and / or cylindrical segments. These segments can be arranged in any order. For example, the coronal-side circular symmetrical unthreaded segment may include cylindrical segments, followed coronally by one or more conical segments. In the presence of multiple conical segments, these segments may be placed sequentially or alternately with one or more cylindrical segments. The cylindrical and conical segments may have different axial lengths, and the conical segments may also have different taper angles.

[0074] The outer surface of a dental implant preferably tapers upwards at least a portion of its length, with the taper occurring within at least the top half of the implant.

[0075] The implant preferably includes external threads for anchoring the implant within the jawbone, these threads projecting from the outer surface of the implant and extending over at least a portion of the implant's length. The external threads are used to initially or directly anchor the dental implant in the jawbone. The external threads can thus extend over the entire length of the dental implant. Alternatively, the external threads can extend over at least 50% of the total length of the dental implant, and preferably over at least 75% of the implant's length, wherein the threads begin at or near the tip (e.g., within 1 mm). The external threads can have any known shape and can include one or more self-tapping grooves. The thread depth of the external threads can remain constant or can vary along the length of the implant. At its coronal end, the outer surface of the dental implant can include an unthreaded portion on the coronal side of the external threads.

[0076] To improve osseointegration, the portion of a dental implant intended for placement in the bone can have a roughened outer surface according to any known technique, or be surface-treated in another known manner (e.g., with a coating). "Outer surface" refers to the external surface and (where present) external threads.

[0077] According to a preferred embodiment, a plurality of implants according to the invention are provided, the plurality of implants having different axial lengths. Within the blind hole of each implant, the position of the threaded section relative to the coronal end of the blind hole is constant. The blind hole of each implant preferably further includes a non-threaded end section extending from the tip of the threaded section to the tip of the blind hole, the axial length of which varies between implants, such that implants with longer axial lengths have longer non-threaded end sections.

[0078] The present invention further relates to a method for manufacturing the dental implant described above by injection molding, wherein a pin is used as a negative template for the threaded section of the blind hole. This means that the outer shape of the pin includes threads corresponding to the inner shape of the threaded section of the blind hole, but taking into account the shrinkage factor of the ceramic after sintering. Therefore, the pin size will be approximately 25% larger than the final implant size.

[0079] Therefore, according to another aspect, the present invention provides a method for manufacturing a dental implant, the method comprising the steps of: providing a mold for ceramic injection molding, the mold comprising a pin extending along a central longitudinal axis and having a threaded section, the threaded section comprising a base surface from which a thread projects radially outward, the base surface defining a minimum radius of the thread as measured from the central longitudinal axis, the thread having a coronal lateral surface and a apical lateral surface, these lateral surfaces being connected at their radially outer ends by a tooth crest, the tooth crest defining a maximum radius of the thread as measured from the central longitudinal axis, the thread extending helically along the axial length of the threaded section and having The threaded section, defined by the radial difference between the abutment surface and the tooth crest, comprises: a main portion in which the maximum radius of the thread remains constant along the length of the main portion; and a tapered portion adjacent to the main portion upwards, in which the maximum radius of the thread decreases in an upward direction from the maximum radius of the thread in the main portion to the minimum radius of the thread at the tip of the tapered portion, the tapered portion extending in an axial length greater than the thread pitch to form a tapered thread with a gradually decreasing thread depth, the tapered thread extending more than one turn; and the use of the mold to produce a dental implant using ceramic injection molding.

[0080] Preferably, the thread of the pin includes, at least along the length of the main portion, a curved transition between the base surface and the top and crown surfaces. Preferably, the transition has an arcuate shape when viewed in longitudinal section. Additionally or alternatively, the thread of the pin includes, at least along the length of the main portion, tooth crests that have a curved longitudinal section, preferably an arcuate shape.

[0081] Further preferred features of the threaded section of the pin complement the preferred features of the threaded section of the implant. For example, preferably, the thread profile within the tapered portion of the pin is modified by gradually removing the radially outer portion of the profile. Additionally or alternatively, preferably, the minimum radius of the thread remains constant along the length of the threaded section. Attached Figure Description

[0082] Preferred embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which:

[0083] Figure 1A A longitudinal section of an implant as known in the art is shown;

[0084] Figure 1B It shows the Figure 1A Enlargement of the threaded section;

[0085] Figure 1C Showing from Figure 1A and Figure 1B Details Y;

[0086] Figure 2A A longitudinal cross-section of an implant according to a preferred embodiment of the invention is shown;

[0087] Figure 2B It shows the Figure 2A Enlargement of the threaded section;

[0088] Figure 2C Showing from Figure 2B Details Y;

[0089] Figure 2D This illustrates the method for producing via injection molding. Figure 2A The implant pin;

[0090] Figure 3 Alternative preferred embodiments of the implant according to the invention are shown; and

[0091] Figures 4A-4E A schematic illustration shows an alternative design for the thread profile within the tapered section. Detailed Implementation

[0092] Figure 1A An implant 1, representing the prior art, is shown. The implant 1 is adapted for use with an auxiliary component (e.g., an abutment (not shown)) and extends from the apex 3 to the coronal end 2 along a central longitudinal axis LA. The implant 1 includes a blind hole 4 that opens at the coronal end 2 and is surrounded by a coronal end surface 5 of the implant 1 that radially surrounds the opening 6. The blind hole 4 is coaxial with the implant 1 and therefore also extends along the central longitudinal axis LA. The outer surface of the implant 1 is provided with external threads 32 for screwing the implant 1 into the patient's jawbone.

[0093] The blind hole 4 includes a threaded section 7 positioned toward the tip of the hole 4. The threaded section 7 includes a base surface 8 from which a thread 9 projects radially inward into the hole 4 (i.e., toward the central longitudinal axis LA). Figure 1B As further detailed, thread 9 has a crown facet 12 and a top facet 14 and extends helically along the length of thread segment 7, the crown facet 12 and the top facet 14 being connected at their radially inner ends by a tooth crest 16. (See also...) Figure 1B As shown, the base surface 8 defines the maximum radius R of the thread 9. max The tooth crest 16 limits the minimum radius R. min The difference between the maximum and minimum radii at any given point gives the thread depth T. D .

[0094] At the top of threaded section 7, the non-threaded conical section 10 intersects with thread 9. This is in Figure 1CThe figure is shown in detail. As can be seen in the figure, the conical surface 10 intersects the top lateral surface 14 at an acute angle, thus forming a thin, sharp edge 18 in the hole. This creates a stress concentration point. When the implant 1 is made of ceramic, such a sharp edge 18 can lead to crack formation and implant failure. As can also be seen in the figure, when viewed in longitudinal section, the tooth crest 16 has a planar shape. Such a tooth crest is the simplest shape formed during implant milling, but it can also lead to problematic stress concentrations in ceramic implants.

[0095] Figure 2A An implant 100 according to the present invention is shown. The implant 100 is made of a ceramic material, such as an aluminum-based, zirconium-based, or magnesium-based ceramic material, such as alumina, zirconium oxide, or magnesium oxide, or combinations thereof. Additionally, a stabilizer (such as yttrium oxide or cerium oxide) may be included in the ceramic material.

[0096] Similar to the prior art implant 1 described above, the implant 100 of the present invention extends from the apex 103 to the coronal apex 102 along a central longitudinal axis LA. The implant 100 includes a coaxial, longitudinally extending blind hole 104 that opens at the coronal apex 102 and extends along the axis LA toward the apex 103. The blind hole 104 includes a threaded section 107 having an abutment surface 108 from which a thread 109 projects radially inward into the hole 104. The thread 109 has a coronal lateral surface 112 and a superior lateral surface 114, which are connected at their radially inner ends by a tooth crest 116. The thread 109 extends helically along the length of the threaded section 107. The abutment surface 108 defines the maximum radius R of the thread 109. max The tooth crest 116 defines the minimum radius R. min The difference between the maximum and minimum radii at any given point gives the thread depth T. D (See Figure 2B ).

[0097] In contrast to existing implant technologies, the threaded section 107 of the implant 100 includes a main portion 115 and a tapering portion 117 adjacent to the main portion 115 at an upward angle. The maximum radius R of the thread 109 within the main portion 115 is... max While remaining constant, within the tapered portion 117, the base surface 108 extends in the upward direction from the maximum radius R of the thread 109 in the main portion 115. max The minimum radius R of the thread 109, which tapers radially inward to the tip of the tapered portion 117. min The tapered portion 117 extends in an axial length greater than the thread pitch to form the thread depth T. D The gradually decreasing tapered thread 119 extends beyond one thread turn. The radial inward tapering of the base surface 108... Figures 4B-4EThe tapered base surface 108 further clarifies this. This results in a thread depth T. D By gradually reducing the number of turns in the thread, a smooth runout is obtained in the thread 109. Therefore, the thread 109 is not abruptly cut off, and the formation of the sharp edge 18 found in the prior art (see...) is prevented. Figure 1C Therefore, stress points within the hole that could lead to crack formation are eliminated.

[0098] Figure 2B An enlarged view of the threaded section 107 is shown. The enlarged view shows how the tapered base surface 108 tapers radially inward at a cone angle γ measured relative to the central longitudinal axis LA, thus forming a conical shape. The cone angle γ remains constant along the length of the tapered portion 117. In this embodiment, the cone angle γ is 8°. This angle is smaller than the cone angle α of the crown side surface 112 measured relative to the central longitudinal axis LA. An obtuse angle is formed between the tapered base surface 108 and both the top side surface 114 and the crown side surface 112, as shown... Figure 2C This is best observed in the middle. The cone angle γ is chosen to ensure that thread runout occurs on more than 3 turns of the thread.

[0099] Within the main section 115, the maximum radius R max Keeping it constant, the result is a base surface 108 with a cylindrical shape. Additionally, the minimum radius R of the thread 109... min The thread profile also remains constant, thus providing a uniform force distribution during use.

[0100] Within the tapering section 117, the minimum radius R min The thread depth is kept constant, so that the reduction is caused only by the taper of the base surface 108. The thread profile remains constant relative to the base surface of the main portion 115. In this way, the thread 109 is gradually submerged by the taper of the base surface 108 from the thread root 121 toward the thread crest 116.

[0101] refer to Figures 4A-4E The diagram schematically illustrates an alternative design for the tapered thread 119. Figure 4A A longitudinal section of a thread 400 having a uniform thread profile (e.g., which may be formed in the main portion of the thread section) is shown. The thread 400 extends from a base surface 408 and has a top side surface 414 and a crown side surface 412 connected by a tooth crest 416. Figures 4B-4E Different ways to change the basic thread profile to form a tapered thread are shown.

[0102] Figure 4B This demonstrates how the thread depth can be reduced by maintaining the cross-sectional shape of the thread 400 while gradually decreasing its size. Figure 4C It shows Figure 4AThe thread profile can be altered by gradually removing the radially inward portion of the profile. In this way, the thread crest 416 changes along the length of the thread, while the transition from the base surface 408 to the side surfaces 414, 412 remains constant. Figure 4D middle, Figure 4A The thread profile is modified by gradually removing the radially outer portion of the profile. In this way, the thread crest 416 remains constant, while the transition from the base surface 408 to the thread flanks 414, 412 is altered. Figure 4C and Figure 4D In both figures, the area of ​​the triangular thread profile is gradually removed, with this removal occurring either at the thread crest or the thread root. As material is removed from the thread crest (the radially inward portion of the profile), this gives the visual impression that the thread tip is being "shorn off," until the thread is completely ground away (see...). Figure 4C When material is removed from the root of the thread (the radially outer portion of the profile), this gives the visual impression that the thread is "submerged" below the base surface (see...). Figure 4D Therefore, the design of the tapered section 117 is an example of this type of contour change.

[0103] exist Figures 4B-4D In this case, the minimum radius of the 400 thread remains constant; however, the minimum radius can potentially increase in the upward direction. This is in... Figure 4E As shown in [the image]. Figure 4E In the process, both the inner and outer portions of the thread profile are gradually removed, making the thread appear as if it has been cut off from the crest and simultaneously submerged from the root.

[0104] Figures 4B-4E Each of the thread designs shown enables a gradual reduction in thread depth to provide the tapered thread of the present invention.

[0105] Return to Figures 2A-2C The implant shown has a curved crown 116, forming an arc in longitudinal section along the entire length of the threaded section 107. Additionally, within the main portion 115, at the abutment surface 108, the transition between the top surface 114 and the crown surface 112 (referred to as the threaded root 121)... Figure 2B The circular bases 121 and 116 between the lateral surfaces also form arcs in the longitudinal section. These circular bases 121 and 116 prevent stress concentration in these narrow areas of the thread 109. While it is possible to create the circular bases 121 on the abutment surface 108 of the implant through milling, the circular 116 cannot be produced by conventional milling techniques. This can be seen in implant 1 of Figure 1, where the 116 is planar in the longitudinal section. To produce the circular 116, implant 100 must be 3D printed or injection molded. Figure 2DThe diagram shows a pin 200, which is suitable for use in injection molding and can be used to produce the threaded section 107 of the implant 100.

[0106] Figure 2D A pin 200 is placed in a mold, thereby having a hollow internal space corresponding to the external shape of the implant to be produced. The pin 200 includes a negative template of the shape of the threaded section 107 of the implant 100, meaning its external shape corresponds to the internal shape of the threaded section 107 within the future implant 100. The pin 200 is sized approximately 25% larger than the desired size of the finished threaded section 107 to accommodate shrinkage occurring during the sintering step of ceramic implant manufacturing. When the hole 104 of the implant includes additional features (e.g., anti-rotation elements), a collar corresponding to the desired additional features is positioned around the pin 200 to appropriately modify the internal shape of the manufactured hole 104. Ceramic material is injected into the mold around the pin 200. This produces a robust, stable green body that can be removed from the mold, and after the pin (and optionally the collar) is removed from the green body, the implant can be sintered to obtain the product according to the invention. Figure 2A The implant shown.

[0107] The pin 200 includes a shank 222 extending from the tip 203 to the crown 202 along a central longitudinal axis LA, and includes an externally threaded section 207. The threaded section 207 includes a base surface 208 from which a thread 209 projects radially outward. In this way, in contrast to the final thread 109 of the implant, the base surface 208 defines a minimum radius R for the thread 209. min Thread 209 has a crown facet 212 and a top facet 214, which are connected at their outermost radial points by a crest 216, the outermost point of which defines the maximum radius R of thread 209. max Since pin 200 is a negative template, the top surface 214 of pin 200 provides the shape of the crown surface 112 of implant 100, while the crown surface 212 of pin 200 provides the shape of the top surface 114 of implant 100. Similarly, the tooth crest 216 of pin 200 defines the abutment surface 108 and the tooth floor 121 of implant 100, while the abutment surface 208 of pin 200 defines the tooth crest 116 of implant 100.

[0108] The threaded section 207 of the pin 200 includes a main portion 215 and a tapering portion 217 adjacent to the main portion 215 in a topward direction. Within the main portion 215, the maximum radius R of the thread 209 is... max Maintain a constant radius. Within the tapering portion 217, the maximum radius R... max Along the upward direction from the maximum radius R of the main part 215 maxReduced to the minimum radius R of the thread 209 at the tip of the tapered section 217. min The tapered portion 217 extends in an axial length greater than the thread pitch, such that a tapered thread 219 is formed within the tapered portion 217, and the tapered thread extends more than one turn.

[0109] The shape of the tooth crest 216 within the tapered portion 217 of the pin 200 is a mirror image of the desired shape of the base surface 108 of the tapered portion 117 of the implant 100 to be manufactured. Therefore, in this embodiment, the tooth crest 216 tapers radially inward at a cone angle of approximately 8°, thereby producing a conical surface.

[0110] Figure 2A The implant 100 shown is adapted for use with auxiliary components (e.g., an abutment (not shown)) or for direct attachment to a prosthesis. Additionally, temporary auxiliary components, such as healing caps or impression posts, can be fitted to the implant 100 prior to attachment to the abutment. All of these components can be attached to the implant 100 via threaded sections 107.

[0111] The outer surface of the implant 100 is provided with external threads 132 and self-cutting grooves 135 for screwing the implant 100 into a drilled hole in the jawbone of a patient (not shown). The threads 132 begin near the tip 103 of the implant and extend to the coronal tip 102. However, in this embodiment, the implant includes an unthreaded coronal neck portion 120. The coronal tip surface 105 of the implant 100 is planar and transverse to the central longitudinal axis LA. The coronal tip surface 105 radially surrounds the coronal opening 106 of the blind hole 104.

[0112] In addition to the threaded section 107, the blind hole 104 also includes a circularly symmetrical unthreaded section 134 located at the coronal end of the hole 104. This coronally symmetrical unthreaded section 134 can be cylindrical or conical, or, as in this example, include multiple conical and cylindrical sections 134a, 134b, 134c. Providing such a coronally symmetrical unthreaded section 134 allows the accessory component to be placed deeper within the implant 100 and thus provides a more stable connection. Any conical surface of the coronally symmetrical unthreaded section 134 (e.g., conical surface 134c) can also be used to form a seal between the implant and the accessory component. Alternatively, the coronal end surface 105 can be used to form a seal with the accessory component.

[0113] The blind hole 104 further includes an anti-rotation element 130. This element 130 is located on the crown side of the threaded section 107 and the top side of the crown-side circularly symmetrical unthreaded section 134. In this embodiment, the anti-rotation element 130 includes a plurality of circumferentially spaced ribs 133 that project radially inward into the hole 104. Therefore, the anti-rotation element 130 has a non-circularly symmetrical cross-section in a plane perpendicular to the central longitudinal axis LA. When an abutment or other auxiliary component with a complementary anti-rotation element is inserted into the hole 104, the engagement of the ribs 133 with complementary grooves in the auxiliary component prevents relative rotation about the central longitudinal axis LA. Such complementary anti-rotation elements are well known in the field of dental implants and can have alternative cross-sectional shapes, such as polygonal, oval, etc.

[0114] Adjacent to the anti-rotation element 130 inside the blind hole 104, the implant 100 includes a cylindrical segment 138 having a non-threaded surface extending into the threaded segment 107 described above. Changing the length of this cylindrical segment 138 changes the depth at which the threaded segment 107 begins, and thus can be used to determine the length of the screw necessary for use with the implant 100. Such a cylindrical segment can be used, for example, to ensure that the threaded segment 107 is located only in the lower half of the implant 100.

[0115] Adjacent to the threaded section 107, the implant 100 includes a non-threaded end section 140 that tapers in a curved manner in the upward direction. The non-threaded end section 140 extends from the tip of the threaded section 107 to the tip 144 of the blind hole 104. The non-threaded end section 140 increases the length of the hole 104 without requiring an extension of the threaded section 107. Increasing the length of the hole 104 reduces the mass of the tip of the implant 100, thus reducing strain during use.

[0116] Because the position of the threaded section 107 determines the length of the screw that can be used with the implant 100, the position of the threaded section 107 relative to the coronal end 102 of the implant 100 generally remains constant despite changes in the total length of the implant 100. This allows the abutment and other auxiliary components to be sold in standard screw lengths that can be used with a range of implants, regardless of their length. Because the position and length of the threaded section 107 generally remain constant, the length of the unthreaded end section 140 can be increased in longer implants to reduce the mass of the top portion of the implant.

[0117] Figure 3 An example of this is shown in the figure. Figure 3 The implant 300 shown basically corresponds to Figure 2AThe implant 100. Specifically, all portions of the threaded section 307 and the hole 304 on the coronal side of the threaded section 307 are connected to... Figure 2A They are the same. Only the top portion of blind hole 304 is different because the non-threaded end portion 340, which is adjacent to the threaded section 307, is different. Figure 2A The equivalent unthreaded end section 140 of the implant 100 shown is much longer. This is because the implant 300 has a greater axial length than the implant 100, and therefore the longer unthreaded end section 340 prevents a large mass at the tip of the implant 300. The unthreaded end section 340 is slightly conical, for example, with a taper angle of 0.5°, to aid in demolding. The taper angle of the unthreaded end section 340 is smaller than the taper angle of the tapered portion of the threaded section 307. At its tip, the unthreaded end section 340 tapers in a curved manner toward the tip 344 of the blind hole 304 in the upward direction. This rounding of the tip of the hole 304 helps to avoid areas of stress concentration.

[0118] As is known in the art, the external surface of an implant can be provided with additive or non-additive surface structures to enhance osseointegration. Such surface structures can be prepared by mechanical polishing, chemical etching, laser processing, additive processing, and combinations thereof, as is well known to those skilled in the art of dental implantology.

[0119] The above embodiments are for illustrative purposes only, and those skilled in the art will recognize that alternative arrangements falling within the scope of the claims are possible. For example, any known anti-rotation element can be used, including anti-rotation elements located on the exterior of the implant. The tapered portion of the threaded section may taper in radius rather than angle, or may include multiple taper angles. The hole may be located in the crown or top portion of the angled implant.

Claims

1. A ceramic dental implant (100, 300) for implantation into the jawbone, the implant extending from a apex (103) to a coronal end (102), the implant having: Blind holes (104, 304) that open toward the crown end (102) of the implant and extend along the central longitudinal axis (LA) toward the apex (103), the blind holes (104, 304) comprising: The threaded section (107, 307) has a base surface (108) from which the thread (109) protrudes radially inward, the base surface (108) defining the maximum radius (R) of the thread (109) as measured from the central longitudinal axis (LA). max The thread (109) has a crown facet (112) and a top facet (114), which are connected at their radially inner ends by a crest (116), the crest (116) defining the minimum radius (R) of the thread (109) as measured from the central longitudinal axis (LA). min The thread (109) extends helically along the axial length of the thread section (107, 307) and has a depth (T) defined by the radius difference between the base surface (108) and the tooth crest (116). D ), The threaded sections (107, 307) include: The main portion (115), within which the maximum radius (R) of the thread (109) is... max The length of the main portion remains constant; and A tapering portion (117) adjacent to the main portion (115) at an upward direction, within which the base surface (108) extends in the upward direction from the maximum radius (R) of the thread (109) in the main portion (115). max The minimum radius (R) of the thread (109) that tapers radially inward to the tip of the tapered portion (117) is... min The tapered portion (117) extends in an axial length greater than the thread pitch to form a thread depth (T). D A gradually decreasing tapered thread (119) extends more than one turn of the thread.

2. The ceramic dental implant according to claim 1, wherein, The minimum radius (R) of the thread (109) min It remains constant over the entire length of the threaded section (107, 307).

3. The ceramic dental implant according to claim 1 or 2, wherein, Within the tapered portion (117), the thread profile of the thread is modified by gradually removing the radially outer portion of the thread profile, i.e., modifying the transition from the base surface (108) to the thread side.

4. The ceramic dental implant according to claim 2, wherein, The thread profile of the thread remains constant along the length of the main portion (115), and within the tapered portion (117), the thread profile remains constant relative to the base surface (108) of the main portion (115), such that within the tapered portion (117), the thread (109) is gradually submerged by the tapered base surface (108).

5. The ceramic dental implant according to claim 1 or 2, wherein, The tapered thread (119) extends at least two turns.

6. The ceramic dental implant according to claim 5, wherein, The tapered thread (119) extends between 2 and 8 turns.

7. The ceramic dental implant according to claim 1 or 2, wherein, Within the tapered portion (117), the base surface (108) tapers radially inward at a cone angle (γ).

8. The ceramic dental implant according to claim 7, wherein, Within the tapered portion (117), the cone angle (γ) of the base surface (108) is constant over the entire length of the tapered portion (117).

9. The ceramic dental implant according to claim 7, wherein, Within the tapered portion (117), the cone angle (γ) of the base surface (108) is smaller than the cone angle (α) of the crown side surface (112) of the thread (109).

10. The ceramic dental implant according to claim 1 or 2, wherein, Within the tapered portion (117), the angle formed between the base surface (108) and the top side surface (114) and the crown side surface (112) is an obtuse angle, i.e. greater than 90°.

11. The ceramic dental implant according to claim 1 or 2, wherein, Along the length of the main portion (115) of the threaded section (107, 307), when viewed in longitudinal section, there is a fully curved transition at their radially outer ends between adjacent top side (114) and crown side (112).

12. The ceramic dental implant according to claim 1 or 2, wherein, At least along the length of the main portion (115), the longitudinal section of the tooth crest (116) is curved, such that there is a fully curved transition at their radial inner ends between the adjacent top surface (114) and the crown surface (112).

13. The ceramic dental implant according to claim 1 or 2, wherein, The implant is produced by injection molding.

14. The ceramic dental implant according to claim 1 or 2, wherein, The implant extends from the top (103) to the crown (102) along the central longitudinal axis (LA), and the blind holes (104, 304) are open at the crown surface (105) of the implant.

15. The ceramic dental implant according to claim 14, wherein, The length of the blind holes (104, 304) measured in the longitudinal direction is greater than 70% of the axial length of the implant.

16. The ceramic dental implant according to claim 1 or 2, wherein, The blind hole (104, 304) further includes, on the top side of the threaded section (107, 307), a non-threaded end section (140, 340) extending from the top of the threaded section (107, 307) to the top of the blind hole (104, 304).

17. The ceramic dental implant according to claim 1 or 2, wherein, The blind holes (104, 304) include an anti-rotation element (130) on the crown side of the threaded section (107, 307).

18. A method for manufacturing dental implants (100, 300), the method comprising the following steps: A mold is provided for ceramic injection molding, the mold comprising: A pin (200) extending along a central longitudinal axis (LA) and having a threaded section (207), the threaded section (207) comprising: A base surface (208) from which a thread (209) protrudes radially outward, the base surface (208) defining the minimum radius (R) of the thread (209) as measured from the central longitudinal axis (LA). min The thread (209) has a crown facet (212) and a top facet (214), which are connected at their radially outer ends by a crest (216), the crest (216) defining the maximum radius (R) of the thread (209) as measured from the central longitudinal axis (LA). max The thread (209) extends helically along the axial length of the threaded section (207) and has a depth defined by the radial difference between the base surface (208) and the tooth crest (216), the threaded section (207) comprising: Main portion (215), within which the maximum radius (R) of the thread (209) is... max The length of the main portion (215) remains constant; and The tapered portion (217) adjacent to the main portion (215) at the top, within which the maximum radius (R) of the thread (209) is... max ) along the upward direction from the maximum radius (R) of the thread (209) in the main part (215). max The minimum radius (R) of the thread (209) at the tip of the tapered portion (217) is reduced to the minimum radius (R) of the thread (209). min The tapered portion (217) extends in an axial length greater than the thread pitch to form a tapered thread (219) with a gradually decreasing thread depth, the tapered thread (219) extending more than one turn of the thread, and The mold is used to produce dental implants using ceramic injection molding.

Images