Bone-adjusting implants

Abstract

The implant for threading into a prepared hole in raw bone has a body extending between a distal end and a coronal end. The threads spiral along the body. The threads have a truncated crest with multiple flute segments formed thereon, which combine to define an array of flutes. The truncated crest also supports an array of condensation ramps configured to apply compressive strain to the interior surface of the hole by a densifying action while the implant is threaded into the hole. The distal end has a pair of cutting lips diametrically opposed to each other. Each cutting lip is formed between a plow surface and a buttress surface. A microbevel is disposed on the buttress surface adjacent to the cutting lip. A valley is disposed at the distal end. The valley allows for the formation of a substantially circular stub at the base of the hole.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 489,233, filed March 9, 2023, and U.S. Provisional Patent Application No. 63 / 498,444, filed April 26, 2023, the entire disclosures of which are incorporated herein by reference.

[0002] The present invention relates generally to implants intended to provide fixation to a host material, more particularly to implants designed to induce new bone ingrowth and osseointegration and improve stability, and even more particularly to such implants placed in bioorganic materials such as bone. [Background technology]

[0003] Threaded implants are used in a variety of applications. For example, in industrial and construction environments, where the host material is wood, concrete, metal, or polymer, the implant can be placed to provide a fixed connection point for attaching another element. Threaded implants are also widely used in medical applications, where the host material is bone, to provide a fixed connection point for metal plates, pins, rods, Kirschner wires, and Küntscher and interlocking nails, among other uses.

[0004] When the host material is bone, a dental implant is another form of threaded implant. Dental implants, also known as endosseous implants or fixtures, are surgical devices used to support dental crowns, dental bridges, dentures, facial prostheses, or to function as orthodontic implants. Typically, such implants are designed as threaded, tapered implants that can be inserted immediately after setting, so that full stability (i.e., secondary stability) can be achieved over time as the surrounding bone grows into and around the implant, a process known as osseointegration. Several months of bone ingrowth may be required before the implant reaches sufficient (secondary) stability to be inserted into a routine loading procedure.

[0005] In many applications, implant stability is an important consideration because the implant must be able to support the intended load. When the host material is not an organic living tissue (such as foams and metals), maximum implant stability is usually achieved immediately after placement. In these situations, the implant should be designed to maximize initial stability, also known as primary stability. In applications where the host material is an organic biomaterial, such as bone or wood, time for healing and ingrowth after placement may be required to achieve full implant stability. In these latter cases, the more quickly the implant can reach an adequate level of secondary stability, the better. Summary of the Invention [Problem to be solved by the invention]

[0006] Implants that have a sufficient level of stability upon initial placement are highly valued. While the prior art consists of numerous different designs and concepts aimed at improving both primary (initial) and secondary (long-term) implant stability, there remains a continuing desire for improvement. Specifically, implant stability remains a long-felt need in the art, where improvements are readily accommodated. There is also a need for improved implants that can facilitate osseointegration at the anterior (tip) end. [Means for solving the problem]

[0007] According to one embodiment of the present invention, an implant for threading into a prepared hole is provided. The implant comprises a body extending longitudinally along a central axis between a distal end and a coronal end. The body has an apical region extending from the distal end and a coronal region extending from the coronal end. A central region of the body is disposed between the distal region and the coronal region. At least one thread protrudes from the body and helically winds along successive turns from the apical region to the coronal region. The thread has a crest. A portion of the body between adjacent turns of the thread comprises a valley. The central region includes an array of flutes. Each flute extends longitudinally along the central region and is composed of a plurality of separate, isolated flute segments. The isolated flute segments are formed at the crest of the thread. The central region includes an array of condensation ramps. Each condensation ramp is disposed along the crest of the thread between two circumferentially adjacent flute segments. Each condensation ramp has a low leading edge and a high trailing edge, in a rightward direction. The tip end has at least one cutting lip having a generally radially extending edge formed between the plow surface and the buttress surface. [Effects of the Invention]

[0008] The unique shape of the tip end with its cutting lip allows the implant to scrape and cut away host material as it is screwed into the prepared hole. Particles of host material (e.g., bone debris) released by the cutting lip accumulate around the tip end as they descend toward the bottom of the hole. These removed bone chips act as seeds for bone growth promoters, thus promoting new bone ingrowth and osseointegration. The faceted shape of the tip end significantly increases the surface area of ​​contact between the bone and the implant, thus improving stability. [Brief explanation of the drawings]

[0009] These and other features and advantages of the present invention will be more readily understood when considered in conjunction with the following detailed description and the accompanying drawings.

[0010] [Figure 1] 1 is a cross-sectional view along a human mandible with an implant fully installed according to one embodiment of the present invention.

[0011] [Figure 2] FIG. 2 is an elevational view of the implant of FIG. 1.

[0012] [Figure 3] FIG. 3 is similar to FIG. 2 but highlights the various body / root tapers as well as the crest tapers of the threads.

[0013] [Figure 4] FIG. 3 is a partial view of the implant of FIG. 2, highlighting the offset between the thread crests and intervening valleys.

[0014] [Figure 5] FIG. 5 is similar to FIG. 4, but with emphasis on thread thickness and thread pitch.

[0015] [Figure 6] FIG. 3 is a distal end view of the implant of FIG. 2.

[0016] [Figure 7] FIG.

[0017] [Figure 8] 8 is another perspective view of the distal end taken from a slightly different perspective than that of FIG. 7.

[0018] [Figure 9] 3 shows the implant of FIG. 2 partially inserted into the prepared hole.

[0019] [Figure 10] FIG. 10 is similar to FIG. 9, but showing the implant fully installed in the prepared hole.

[0020] [Figure 11] FIG. 11 is an enlarged view of the area surrounded by 11 in FIG.

[0021] [Figure 12] FIG. 10 is an elevational view of an implant according to an alternative embodiment.

[0022] [Figure 13] FIG. 13 is a partial perspective view of the distal end of the alternative implant of FIG. 12.

[0023] [Figure 14] FIG. 13 is a general perspective view of the alternative implant of FIG. 12.

[0024] [Figure 15] 13 shows the implant of FIG. 12 fully installed in the prepared hole. DETAILED DESCRIPTION OF THE INVENTION

[0025] Referring to the drawings, wherein like numerals indicate like or corresponding parts throughout the several views, the present invention will be described in the context of dental implants, which require the preparation of a bone resection in the jawbone to receive a bone implant ( FIG. 1 ). It will be understood that the present invention is not limited to dental applications, but may be applied across a wide range of orthopedic applications. Furthermore, the present invention is not limited to use in bone. To name a few, the present invention may be used to provide implants in live wood and other living cell materials, as well as metal foams and other non-living cell host materials used in various industrial and commercial applications. However, because dental applications are a convenient example, the following description will use a dental context using bone as the host material for illustrative purposes.

[0026] 1 shows a cross-section of an edentulous jaw site having implanted therein an implant 20 according to one embodiment of the present invention. The implant 20 is of a type that can be screwed into a prepared hole in a host material. When the host material is bone, the prepared hole is called an osteotomy.

[0027] The prepared hole, or osteotomy, can be formed using any suitable technique. One such technique involves the use of a progressively wider rotary osteotome specifically configured to achieve osseodensification along the surrounding bone wall. The procedure for forming an osteotomy using a progressively wider rotary osteotome is generally described in U.S. Pat. No. 9,326,778 to Huwais, issued May 3, 2016, supra. See also U.S. Pat. No. 10,980,548 to Huwais, issued April 20, 2021. The entire disclosures of these documents are incorporated herein by reference and relied upon in all jurisdictions that recognize incorporation by reference.

[0028] Once the bone resection has been prepared, again by any suitable technique, the implant 20 is screwed into place, as illustrated in FIG. 1 , by normal right-handed rotation. According to well-known practice, an abutment (not shown) is finally threaded into the internal connection, thereby securing it in place to receive a subsequent restoration or dental crown (also not shown). While the implant 20 is perhaps ideally suited for placement within bone, non-bone applications are also possible. Again, while the illustrated embodiment represents the implant 20 in the form of an implant or receptor for dental restorations, it should be understood that the implant 20 may be reconfigured as a bone screw or other bone fixation element, such as may be used in implants for the spine, hip, shoulder, wrist, and other orthopedic applications, as well as various non-medical applications.

[0029] Implant 20 can be designed to fit into prepared holes of various diameters. Although not shown, implants 20 of various lengths and diameters suitable for prepared holes of various depths and diameters are similarly possible. Those skilled in the art will appreciate that the principles of the present invention can take many different forms without departing from the spirit of the teachings. With this understanding, the present invention will be described in connection with the general examples illustrated in Figures 2-11.

[0030] 2 and 3, implant 20 includes a truncated body formed with a tapered outer profile. The body of implant 20 extends longitudinally along a central or longitudinal axis A. The body has an apical end 22 and a coronal end 24. The terms "apical" and "coronal" are selected primarily for their dental associations. "Apical" refers to a direction toward the root end of the tooth, and "coronal" refers to a direction toward the crown or crowns. Applicant's use of these terms, and possibly other terms herein, should not be construed to limit the application of implant 20 to the dental or even medical fields. Coronal end 24 is preferably flat or substantially flat and serves as a platform for a dental restoration or other subsequent attachment to implant 20. Apical end 22 forms the tip of implant 20 and, in use, is initially inserted into a prepared bone resection. The distal end 22 includes several unique features, which will be described below with particularity.

[0031] The implant 20 has an apical region 26 adjacent the distal end 22 and a coronal region 28 adjacent the coronal end 24. The apical region 26 represents the portion of the body extending from the distal end 22. Similarly, the coronal region 28 represents the portion of the body extending from the coronal end 24. A central region 30 of the body extends between the apical region 26 and the coronal region 28. The central region 30 is contiguous with the apical region 26 and the coronal region 28 on either end, such that in the illustrated example, these three regions 26, 28, 30 completely occupy the entire longitudinal length of the body, from the distal end 22 to the coronal end 24.

[0032] In Figure 3, the outermost surface of the body can be readily identified as having a tapered profile. In particular, the individual regions 26, 28, 30 can be distinguished from one another by, among other things, the tapered characteristics of the body. Thus, it is reasonable to describe the body as having a distal taper R1 throughout distal region 26, a coronal taper R3 throughout coronal region 28, and a central taper R2 throughout central region 30.

[0033] The tip taper R1 can be between about 2° and 30° as measured from the central axis A. In some embodiments, the tip taper R1 can be between 7° and 18°. The illustrated example represents a tip taper R1 in the range of 10° to 15°. By specifying that the taper angle is measured from the central axis A, it is understood that this is the half-maximum angle. The full taper of the cone would be twice the given measurement.

[0034] The central taper R2 may be approximately −5° to +15° as measured from the central axis A. As can be seen from the negative lower limit of the stated range, it is contemplated that the central taper R2 may in some cases be formed with a reverse taper. However, in most embodiments, it is expected that the lower limit of the central taper R2 will be non-negative, such as in a more limited range of approximately 0° to 10°. The illustrated example represents a central taper R2 in the range of 0° to 5°.

[0035] The crown taper R3 may be between about 5° and 35°, more particularly between 10° and 25°, measured from the central axis A. In some embodiments, the crown taper R3 may be between 15° and 20°.

[0036] In bone applications, these ranges may represent important boundaries in that failure to adhere to the range limits may result in either too little radial compression or too much radial compression. The apical taper R1 and the crown taper R3 do not need to be substantially equal, i.e., they do not need to match one another. In some dental applications and some non-dental orthopedic applications, a somewhat larger taper range may be desirable. In non-medical applications, even larger taper ranges may be considered.

[0037] In practice, the longitudinal lengths of the distal region 26, the crown region 28, and the central region 30 can vary relative to the overall longitudinal length of the body and the relative taper angles R1, R2, and R3. For example, in the illustrated embodiment, if the longitudinal length of the distal region 26 is specified as 1 unit, the length of the central region 30 is approximately 1 1 / 3 units, and the crown region 28 is approximately 1 3 / 4 units. By these rough measurements, the overall longitudinal length of the body is therefore just over 4 units. Naturally, the relative lengths of the distal region 26, the crown region 28, and the central region 30 are highly adaptable to suit the intended application. That is, these dimensional relationships can be altered to suit the application and / or achieve particular performance attributes. For example, the distal region 26 can be relatively longer or shorter, the crown region 28 can be relatively longer or shorter, and the central region 30 can be relatively longer or shorter. Of course, many additional alternatives will be apparent to those skilled in the art. Despite varying relative lengths, the body geometry should maintain a generally conical taper (i.e., R1, R2, R3) that widens, on average, toward the coronal end 24. A conical shape is believed to support superior primary stability and loading protocols. However, the present invention can be practiced with success with true straight and near-straight implant geometries. Thus, the principles of the present invention are not limited to implant designs having only a conical shape.

[0038] An internal tool socket is disposed in the body and opens directly from the coronal end 24, as is well known in the art. The tool socket may extend through the coronal region 30 and fully into the central region 30. The tool socket may be in the form of a hexagonal receptacle for mating with a complementary shaped driver head. Naturally, the form of the tool socket will conform to the application and standards of the relevant industry / field of use. The tool socket is formed as a through feature that allows access to the recessed threads. The threads are configured to connect to an abutment or other feature that is subsequently attached to the implant 20.

[0039] As shown throughout the several figures, at least one thread 32 protrudes from the body. The phrase "at least one" is used to emphasize that in some contemplated embodiments, the implant 20 may be configured with a double-start or triple-start thread 32. However, in the illustrated example, the thread 32 is configured with a single lead that helically wraps fully and continuously from the apical region 26 through the entire central region 30 to the coronal region 28. In most contemplated applications, the thread 32 will wrap right-handed around the body, in accordance with most common convention. Of course, if a particular application requires a left-handed winding to be preferred, a perfect mirror image of the implant 20 would be expected to function in a similar manner.

[0040] The thread 32 has an apex 34 at the apex of its leading and trailing flanks, as is generally common in threaded fasteners and mechanisms. For clarity, the leading flank is the helical surface of the thread 32 facing the distal end 22, and the trailing flank is the helical surface of the thread 32 facing the coronal end 24. If the leading and trailing flanks of the thread 32 were fully extended, they would meet at a sharp edge, forming a blade-like apex. However, in this case, the apex 34 is truncated or flattened. In the illustrated example, the apex 34 has a thickness that can be measured at any point along the axial or longitudinal direction. As described below in connection with FIG. 5, the thickness of the apex 34 can be configured to provide active functions and novel attributes to the implant 20.

[0041] In FIG. 3, the apexes 52 are shown in a generally conical alignment, as identified by a generally common apex taper C. The apex taper C can be any suitable angle. In some embodiments, the apex taper C can be between about 1° and 15° as measured from the central axis A. In the example of FIG. 3, the apex taper C is in the range of 3-4°, which has been found to provide satisfactory results.

[0042] In accordance with standard thread nomenclature, the thread 32 is known to have a root diameter established by the body and a major diameter established by the crest 34. The portion of the body between adjacent turns of the thread 32 comprises the root. The root diameter corresponds to the diameter of the root of the thread 32. Referring now to FIG. 4, at any point along the thread 32, the difference between the root diameter and the major diameter can be measured as an offset 36 between the crest 52 and the root or body of the implant 20. In FIG. 4, the offsets 36 are shown as a group, rather than individually, by dashed lines and vectors. Thus, along the winding path of the thread 32, the offset 36 can be measured radially from the crest 34 to the root. Careful observation reveals that at any point along the thread 32, in most cases the offset 36 on the trailing flank is not equal to the offset 36 on the leading flank.

[0043] As previously mentioned, the thread 32 has a thread thickness. The thread thickness is the axial dimension between the leading flank and the trailing flank as measured at the apex 34. The thread thickness may vary along the entire length of the thread 32, or may vary along at least a portion of its length. FIG. 5 shows that the thread thickness may be greater in the central region 30 and thinner in the tip 26 and crown 28 regions. As explained below, it is believed that a variable thread thickness that is greater in the central region 30 than in the tip 26 and crown 28 regions may provide certain advantages.

[0044] Additionally, the center point of each apex 34 can be used to determine the thread pitch. In FIG. 5, the pitch of the thread 32 is identified from the indicated center point. The pitch can be any suitable low angle. In some contemplated embodiments, the pitch will be approximately constant along the length of the body. However, in the illustrated example, the pitch is not uniform. From FIG. 5, it can be observed that the pitch of the tip region 26 increases or lengthens slightly as it enters the central region 30. Then, the pitch decreases or shortens slightly as it reaches the crown end 24.

[0045] The valleys between the turns of the thread 32 remain generally parallel to the central axis A as they spiral along the body. The axial lengths of the valleys between the turns of the thread 32 are generally equal along the length of the body. At any point along the thread 32, the axial length of the valleys will be generally the same. Notably, as the thread thickness 38 varies, the axial length of the valleys remains generally constant in the illustrated example.

[0046] The combined effects of the unequal offset 36 (front flank versus back flank), varying thread thickness, and gradually varying thread pitch, along with the nearly constant axial length of the roots, interact upon insertion into a biological host material such as bone by alternately compressing and expanding the cellular structure. In the case of bone and other biological tissues, this cyclical compression and expansion action activates the natural healing response, promoting regeneration and ingrowth. These rapidly result in long-term stability of the implant 20.

[0047] The central region 30 of the implant 20 includes an array of flutes 40. Any reasonable number of flutes 40 is possible. The end view of FIG. 6 shows an embodiment in which eight flutes 40 are formed on the implant 20. Regardless of the number of flutes, the flutes 40 are preferably equally spaced circumferentially from one another. In an example in which the implant 20 includes eight flutes (e.g., FIG. 6), each flute 40 would be circumferentially offset by 45° from the next adjacent flute. Each flute 40 extends longitudinally along the length of the central region 30, perhaps best shown in FIG. 2. That is, the flutes 40 are primarily confined to the central region 30; except for some limited intrusions, the flutes 40 do not extend significantly into either the apex 26 or crown 28 regions in the illustrated example. In other contemplated embodiments (not shown), the flutes can substantially and / or completely traverse one or both of the apex 26 and crown 28 regions.

[0048] It will be observed that the flutes 40 are not continuous, uninterrupted grooves. Instead, each flute 40 is composed of a plurality of distinct, isolated flute segments separated from one another by gaps between turns in the thread 32. Each isolated flute segment is formed as a scallop at the crest 34 of the thread 32. That is, each flute 40 is actually formed by an alignment of several independent flute segments, perhaps similar to a walking path formed by a series of individual, but spaced, stepping stones. The spaces or gaps between the turns of the thread 32 intersect the flute 40 at each revolution, thereby dividing each flute 40 into a series of segments, as easily understood from the end view of FIG. 6 . Thus, the collection of flute segments establishes a single flute 40. For convenience, it will be assumed that each flute 40 is comprised of an average of seven flute segments, and if the implant 20 has eight flutes 40, the total number of flute segments is approximately 56, evenly distributed around the outside of the central region 30 of the implant 20. The flutes 40 have the beneficial effect of increasing the surface configuration to provide more bone contact with the implant 20, thereby resulting in better stability.

[0049] Each separated flute segment within a common flute 40 is circumferentially offset from the next adjacent separated flute segment to form a helical twist. The helical twist is readily apparent from FIGS. 2 and 6. (A helical flute 40' is also apparent in the alternative embodiment of FIG. 14.) In one example, each flute segment may be circumferentially offset by -10° from the next adjacent separated flute segment. In this case, the helical twist of each flute 40 would be -10°. A negative value of helical twist (e.g., -10°) indicates a left-handed twist. That is, it will be appreciated that the flutes 40 proceed or propagate in a direction opposite to the rotational direction required to thread the implant 20 into its prepared hole. Of course, the -10° twist is provided by way of example, and other degrees of twist are contemplated and within the scope of the present invention.

[0050] In the illustrated example, each flute 40 has a substantially constant flute depth and a substantially constant flute width / span. That is, the size and shape of each flute segment is substantially the same. However, this is not a requirement. In some contemplated embodiments, flutes 40 may be formed with varying depths and / or widths and / or with variable helical twist 62.

[0051] The advantage of left-handed twist in the flutes 40 is understood in the context of implant 20 removal. Most host materials will grow and / or expand within the flutes 40 after placement, especially if the host material is live bone. This movement can be motivated by elastic and semi-elastic material recovery (springback) due to stress introduced into the host material, as well as ingrowth in the case of living host materials such as bone and live wood. The host material entering the flutes 40 will mechanically lock the implant 20 in place. Any attempt to unscrew the implant 20 will be resisted by the host material trapped inside the flutes 40, which will behave like a mechanical obstacle due to the left-handed twist.

[0052] In the illustrated example, each flute 40 has a substantially constant flute depth and a substantially constant flute width / span. That is, the size and shape of each flute segment is substantially the same. However, this is not a requirement. In some contemplated embodiments, flutes 40 may be formed with varying depths and / or widths and / or with variable helical twist 62.

[0053] The central region 30 also includes an array of condensation ramps 42 arranged along the crests 34 of the threads 32 between the flute segments. That is, the condensation ramps 42 are positioned on the crests 34 between adjacent flutes 40 in the central region 30. Each condensation ramp 42 has a low leading edge and a high trailing edge arranged in a rightward direction. That is, the adjectives "leading" and "trailing" refer to the rightward rotation of the implant 20 as it is threaded into the prepared hole. The low leading edge precedes the high trailing edge, which rotates like a ramp or wedge. Further details regarding the condensation ramps 42 can be found in International Publication No. WO 2020 / 086611, the entire disclosure of which is incorporated herein by reference and relied upon in all jurisdictions recognizing incorporation by reference.

[0054] Each condensing ramp 42 is configured to apply a localized compressive strain to the interior surface of the host material through a densifying action while the implant 20 is threaded into the prepared bore. More specifically, the helical strips of host material that rub against the crests 34 of the threads are directly affected by the condensing ramps 42. Meanwhile, areas of the host material that do not rub against the crests 34, i.e., areas along the gaps between the threads 32, are not directly affected by the condensing ramps 42. As the condensing ramps 42 drag across the interior surface of the bore, they create localized areas of highly agitated and highly compacted bone (or other host) material, which may be referred to as superactivation zones. The condensing ramps 42 also induce stresses in the surrounding host material through their wiping action. It will be appreciated that placement of the implant 20 causes the helical strips of host material to be superactivated by the condensing ramps 42, while the intervening helical strips of host material are substantially less stressed. A helical strip of superactivated host material can be thought of as being laid along the path of the embedded threads 32, while a helical strip of low stress host material fills the voids between the threads 32. As a result, the act of screwing the implant 20 into place creates a double helix of superactivated, low stress host material in the wall of the hole.

[0055] Almost immediately, the biohost material will begin to fill the voids of the flutes 40. The induced stress, within the host material's ability to elastically deform, will reverse itself as a reaction force, returning to an undeformed state as soon as the stress is removed. Thus, the reaction force will cause the surrounding bone or host material to spring back into the voids of the flutes 40. The effect is that the host material will contract around the implant 20 and flow into the flutes 40.

[0056] The scallops at the crests 34 of the threads 32 provide space to accommodate bone springing back toward its previous shape. This phenomenon allows the flutes 40 to be understood as healing chambers. That is, the healing chambers effectively attract bone (or other host material). The healing chambers function as incubator sites to rapidly achieve secondary stability. The healing chambers encourage and promote bone inflow to fill the void.

[0057] In a biohost material, such as bone, when induced stress exceeds the bone's ability to deform elastically, the bone will permanently change shape through plastic deformation. In bone, the permanent change in shape may be associated with microcracks that allow energy release, a natural defense against complete fracture. The microcracks are thought to generate blood flow, which leads to the formation of blood clots within the voids of the flutes 40. All of this agitation activates the bone's natural healing properties, resulting in rapid growth of new bone into the flutes 40. The hyperactivation zones thus promote the body's natural healing properties, facilitating recovery and improving osseointegration, particularly to the healing chambers formed where each flute segment rests after the implant 20 is fully installed.

[0058] Over time, a strong, dense layer of new bone growth surrounds the implant 20, accelerated by the combination of the hyperactivation zone and the reaction force. The healing chambers fill with hard new bone, securing the implant 20 in place. Previously, it was estimated that the illustrated implant 20 may have a total of approximately 56 flute segments. This means that 56 separate healing chambers, evenly distributed around the entire exterior of the central region 30, incubate new bone growth and accelerate the osseointegration process. This wide, even distribution of isolated healing chambers hyperaccelerates the healing process while almost instantly mechanically securing the implant 20 in place.

[0059] The host material trapped in the gaps between the turns of the threads 32 is substantially undisturbed as the implant 20 is threaded into place. The nearly constant axial root length means that the section of host material between the turns of the threads 32 is not directly interrupted to the same extent during installation of the implant 20. In contrast, the helical band of host material engaged by the crests 34 of the threads 32 is highly agitated and disturbed by threading the implant 20 into place due to the condensation ramps 42. This highly agitated and disturbed band of host material does not directly affect the host material located within the gaps between the turns of the threads 32. As a result, the natural structural integrity of the host material remains largely intact in the gaps between the turns of the threads 32.

[0060] The host material trapped in the gaps between the turns of the threads 32 may be referred to as a controlled compression zone. The controlled compression zone is a helical band of host material between the body of the implant 20 (i.e., the roots of the threads 32) and the crests 34 of the threads 32, from the distal end 22 to the coronal end 24. This controlled compression zone can be designed to manage the effects on the host material. Considering again FIG. 4, in the distal region 26, the controlled compression zone gently and progressively displaces the host material in both the roots and crests 34 of the threads 32. This is represented by the variable rate of change of the difference between the root and major diameters of the threads 32, i.e., the offset 36, along the length of the implant 20. As the rate of change of the offset 36 decreases, i.e., as the relative length of the dashed vector in FIG. 4 decreases, the relative displacement of the host material also decreases in the helical band affected by the crests 34 of the threads 32. Relatively speaking, both the roots and crests 34 of the threads 32 are pushing outwardly against the host material in the tip region 26 of the controlled compression zone, but the effect of the crests 34 will be diminished.

[0061] Generally, the condensation ramps 42 follow the same twist orientation as the flutes. Thus, if the flutes 40 have a left-handed twist, the condensation ramps 42 will similarly have a left-handed twist. The condensation ramps 42 have a wiping or scraping effect on the interior surface of the prepared hole. The left-handed twist of the condensation ramps 42 each imparts an oblique slope that naturally imparts an axially outward stress to the hole walls as well as any host slurry (e.g., bone particles mixed in a fluid). By "axially outward," we mean that the component of the directional stress is away from the bottom of the prepared hole toward its opening; i.e., upward as viewed in FIGS. 1, 9, and 10.

[0062] In the central region 30 of the controlled compression zone, both the roots and crests 34 of the threads 32 are pushing outward on the host material at approximately the same rate, as can be seen by considering the relatively equal central taper R2 and crest taper C in Figure 3. Thus, although the tip region 26 begins the unequal relative displacement of the controlled compression zone and the hyperactivation zone, influenced by the crest 34, throughout the central region 30, the continuous displacement of the host material is relatively equal. Entering the crown region 28 of the controlled compression zone, it again experiences unequal relative displacement relative to the hyperactivation zone. One purpose of this configuration is to massage the radial stress of the host material. For example, in human bone, a hard layer of cortical bone is typically located on the surface, while softer cancellous bone is located in the interior. See Figure 1. By modulating the radial stress in the hard cortical bone region, stress fractures are less likely to occur around the implanted implant 20.

[0063] This conditioning action can induce a specific, desirable preconditioning effect: initial, gentle compression of bone particles displaced by either the implant's valleys or the crests 34 of the threads 32. Note that the bone particles affected by the implant's preconditioning effect can be either live autograft particles, natural live bone particles, or a mixture of both. In either case, the preconditioning effect activates and energizes the live bone and bone particles. The conditioned stress on the bone particles allows for some particle shifting and alignment of microcracks that would otherwise form during the initial hole formation process. As a result, a significant portion of the sidewall of the osteotomy is cold-worked back and forth, inducing rapid healing of the affected bone particles and osseointegration with the implant 20.

[0064] When implant 20 is initially placed, the host material trapped in the gaps between the turns of thread 32, i.e., the so-called controlled compression zone, functions to provide implant 20 with a favorable high level of initial or primary stability. During these moments and for several days after placement of implant 20, there is insufficient time for the healing chamber to fill and achieve osseointegration. During this phase, the host material in the gaps between the turns of thread 32 primarily secures implant 20 in place. When sufficient time is allotted for new bone growth through the hyperactivation zone and healing chamber, the new bone growth provides substantially enhanced secondary stability of implant 20, allowing for full fit under all normal conditions.

[0065] The tip end 22 is defined by at least one, and preferably a pair of, cutting lips 44. The cutting lips 44 are actually edges disposed on opposite sides of the tip end 22. When there is a pair of cutting lips 44, the edges may or may not lie in a common plane passing through the central axis A. In the illustrated embodiment of FIG. 6, it can be observed that the cutting lips 44 do not lie in a common plane. Rather, the cutting lips 44 are slightly laterally offset (with respect to direct diametric alignment) in this example by a short span on opposite sides of the central axis A. To maintain balance and symmetry, it is advantageous for the pair of cutting lips 44 to be disposed diametrically opposite one another, even if they are not coplanar.

[0066] The aforementioned edges of each cutting lip 44 extend generally radially. Considering the example of FIG. 6, where each edge is offset from the central axis A, it is understood that these edges extend largely or primarily radially, even though they are not actually aligned along radii radiating from the central axis A. Even slightly radially extending edges may be implemented with success. Each edge is formed between a plow surface 46 and a buttress surface 48. The plow surface 46 may be curved or planar, depending on the manufacturing technique used and the designer's preferences. In the illustrated example, the plow surface 46 is generally planar and lies in a plane generally parallel to the central axis A. The buttress surface 48 may also be curved or planar. In the illustrated example, the buttress surface 48 is generally planar.

[0067] 6-8, it can be seen that each cutting lip 44 has a substantially planar microbevel 50. It is understood that the microbevel 50 is optional; that is, a microbevel 50 may be added to the buttress surface 48 adjacent the edge, although the implant 20 may function acceptably without the microbevel 50. The microbevel 50 forms a secondary bevel relative to the primary bevel established by the buttress surface 48. The microbevel 50 is inclined at a microbevel angle from the respective cutting lip 44, thereby improving the cutting performance of the cutting lip 44. The microbevel angle can be varied between approximately 25° and 60° to optimize performance and durability for an application. In practice, the microbevel angle may be approximately 45° measured as a plane relative to the central axis A. In the illustrated example, where the plow surface 46 is parallel to the central axis A, the same measurement would be seen if the microbevel angle measurement were made directly between the intersecting plow surface 46 and the microbevel 50. It will be appreciated that when the implant 20 is screwed into place, the two opposing microbevels 50 are set in opposite directions so that the microbevels 50 follow their respective cutting lips 44. In this configuration, the implant 20 naturally rotates in a cutting direction in which the cutting lips 44 cut or slice bone at the base of the osteotomy. Alternatively, the cutting direction can be defined as a rotational sweep of the cutting lips 44 into bone (or other host material for non-medical applications).

[0068] Each buttress surface 48 is formed adjacent to and away from each microbevel 50 at a primary angle. The primary angle is less than the microbevel angle. In an example where the microbevel 50 is formed at 45° relative to axis A, the buttress surface 48 may be 40° or less. Typically, the difference between the microbevel angle and the primary angle is only a few degrees, often less than 10°.

[0069] In the example shown, the feed ramps 52 are positioned at the base of the plow face 46. The feed ramps 52 extend between the buttress face 48 and the plow face 46. In the example shown, the feed ramps 52 are formed adjacent to and away from each buttress face 48 at a cubic angle. The cubic angle is less than the primary angle. In the example described above, where the buttress face 48 is formed at 40° relative to the axis A, the feed ramps 52 (i.e., the cubic angle) may be 30° or less. Each feed ramp 52 is disposed in a sector of the tip end 22 between the buttress face 48 and the cutting lip 44.

[0070] The feed ramp 52 has at least two functions. One such function is to form at least one, and preferably multiple, self-tapping teeth on the plow face 46. This is accomplished by the feed ramp 52 bisecting one or more turns of the thread 32, as seen in FIGS. 7 and 8. This creates one or more sharp teeth in the tip region 26 that cut clearance for the thread 32 as it advances through the host material with a screwing action. Another function of the feed ramp 52 is described below in connection with FIGS. 10 and 12.

[0071] Some contemplated embodiments of the implant 20 may omit the feed ramp 52 by simply configuring and extending the buttress surface 48 adjacent to the opposing plow surface 46. In these cases, the buttress surface 48 performs the function of the feed ramp 52.

[0072] In the embodiment of Figures 1-8, the implant 20 is shown including a valley 54 located at the distal end 22. The valley 54 is shown in these examples as a short, offset space between the cutting lips 44. That is, the distal end 22 of this embodiment is formed with a groove-like space or notch. The valley 54 is shown extending transversely to the central axis A and generally perpendicular to the plow surface 46. Alternatively, the valley 54 may extend generally perpendicular to the cutting lips 44, separating the cutting lips 44 from one another.

[0073] 2 and 3, the valleys 54 may have a generally flat bottom with generally axial sidewalls, although other shapes for the valleys 54 are contemplated, including U-shaped cross grooves, V-shaped cross grooves, as well as other configurations.

[0074] 9 shows the implant 20 partially inserted into a prepared hole. As the implant 20 is lowered into the prepared hole by a threading action, the outermost edge of the cutting lip 44 scrapes and cuts the host material, and the self-tapping teeth cut grooves in the threads 32, while the valleys 54 have little or no interaction with the host material. Particles of host material (e.g., bone) generated by the cutting lip 44 and self-tapping teeth accumulate around the leading end 22 as it descends toward the bottom of the hole.

[0075] FIG. 10 shows the implant 20 after it has reached the final depth of the prepared hole. In most cases, the original bottom of the hole will be slightly shallower than the entire length of the implant 20. In such cases, i.e., if the implant 20 is longer than the prepared hole, just before reaching full depth, the cutting lip 44 begins scraping and cutting the base of the hole, cutting bone and generating a certain amount of bone debris 56. The bone chip-like debris 56 removed and lifted by the cutting lip 44 collects on the feed ramp 52, piled up against the plow surface 46. These removed bone chips 56 act as seeds for bone growth promoters, facilitating new bone ingrowth and osseointegration.

[0076] A well-documented product of the bone densification method described in U.S. Patent No. 9,326,778 and U.S. Patent Application Publication No. 20190029695 is a layer of bone slurry along the sidewalls of the osteotomy at its base. Indeed, the amount of bone slurry is typically greatest at the base of the osteotomy. This bone slurry is highly beneficial to the healing process. Bone ingrowth as well as regrowth and osseointegration are all substantially enhanced and promoted by this bone slurry resulting from the bone densification process. Toward this end, as shown in FIG. 10 , as the distal end 22 of the implant 20 enters this pool of bone slurry, the bone slurry will be compressed and begin to move upward (i.e., toward the coronal end 24).

[0077] As previously mentioned, the condensation ramp 42 has a wiping or scraping effect on the interior surface of the prepared bore. The oblique inclination of the condensation ramp 42 naturally imparts axial stress to the bore wall as well as to the bone particle slurry as the implant 20 is screwed into place, much like the impeller of a turbine pump. Under the influence of this applied stress, the bone slurry moves as if being pumped toward the open end of the bore by the combined effect of the condensation ramp 42 and the contracting volume indicated by the offset 36 in the distal region 26. It can be seen from FIG. 5 that as the moving bone slurry is lifted into the central region 30, the current increase in volume indicated by the expansion offset 36 in that central region 30 serves to more quickly draw the bone slurry toward the open end of the bore. That is, by comparing the rate of change of the offset 36 in the distal region 26 with that in the central region 30, it can be seen that any fluid material contained in these spaces is subject to both positive and negative pressure forces as the implant 20 is screwed into place. In the central region 30, a relative vacuum of some kind lifts and draws up bone particles and bone slurry from the base of the prepared hole. By actively distributing the bone slurry along the length of the implant 20, the beneficial healing effects described above can be maximized. Thus, the bone slurry is drawn into healing chambers distributed around the implant 20 where bone growth can occur at multiple, dispersed sites.

[0078] To prevent excessive bone slurry from being drawn out of the hole, the crown taper R3 is preferably larger than the central taper R2. In this way, the crown taper R3 can perform a corking function. That is, bone slurry moving toward the open end of the hole due to the offset 36 configuration of the apical 26 and central 30 regions is blocked or at least delayed by the relatively large crown taper R3. Ideally, little or no bone slurry will leak out of the prepared hole before the implant 20 is fully seated. In this way, the novel shape of the implant 20 maximizes the healing potential of the bone slurry, thereby shortening healing time and improving the ultimate stability of the implant 20.

[0079] In the enlarged view of Figure 11, when the implant 20 is at its final depth in the osteotomy, a certain amount of bone debris 56 can be seen piled up against the plow face 46 in the central chamber formed between the valley 54 of the implant 20 and the prepared base of the osteotomy. These bone chips 56, collected in the feed ramps 52 and valley 54, behave as bone growth promoters, promoting new bone ingrowth and osseointegration. However, due to the valley 54, the central portion of the base of the osteotomy is left relatively undisturbed by the implant 20. The undisturbed area is located above the rotation of the cutting lip 44, and therefore takes the form of a roughly circular stub 58. The stub 58 is a feature that enhances the stability of the implant 20. The stub 58 functions as a bone self-locking point or short tenon that attaches within the valley 54 to further resist lateral displacement under load. Furthermore, the valley 54 significantly increases the surface area of ​​the distal end 22, thus increasing bone-to-implant contact and providing greater stability.

[0080] The distal end 22 can be fashioned in a variety of ways different from the design shown in FIGS. 1-11 with the valley 54. Some contemplated embodiments may use a simple obtuse or rounded shape for the distal end 22. FIGS. 12-15 illustrate an alternative embodiment of the implant 20′, in which the aforementioned valley 54 is omitted in favor of a chisel point 60′. As in the previous example, the cutting lip 44′ here is an edge that angles upward and outward (approximately radially) from the distal end 22′. Each cutting lip 44′ is formed between a plow surface 46′ and a buttress surface 48′. A microbevel 50′ can be added to the buttress surface 48′ adjacent to the cutting lip 44′. A feed ramp 52′ is positioned at the base of the plow surface 46′ and extends to the adjacent buttress surface 48′.

[0081] As in the previous example, the outermost edge of the cutting lip 44' scrapes and cuts away host material, and the self-tapping teeth cut grooves in the threads 32' as the implant 20' is threaded into the prepared hole. Particles of host material (e.g., bone debris 56') released by the cutting lip 44' and self-tapping teeth accumulate around the tip end 22' as they descend toward the bottom of the hole. The bone debris 56' collects on the feed ramp 52', where it piles up against the plow surface 46'. These removed bone chips 56' act as seeds for bone growth promoters, facilitating new bone ingrowth and osseointegration. While this case may lack a feature corresponding to the stub 58 of the previous embodiment, the faceted shape of the tip end 22' nevertheless significantly increases the surface area of ​​bone-to-implant contact, thus providing greater stability.

[0082] The foregoing invention has been described in accordance with the relevant legal standards and, as such, the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiments will be apparent to those skilled in the art and are within the scope of the invention.

Claims

1. An implant of the type that is screwed into a prepared hole, said implant comprising: a body extending longitudinally along a central axis between a distal end and a coronal end, the body having a distal region extending from the distal end, the body having a coronal region extending from the coronal end, a central region of the body disposed between the distal region and the coronal region; at least one thread projecting from the body and helically winding along continuous turns from the apical region to the coronal region, the thread having a crest and a portion of the body between adjacent turns of the thread including a valley; Equipped with the central region includes an array of flutes, each flute extending longitudinally along the central region, each flute being comprised of a plurality of separate, isolated flute segments formed at the crests of the threads; the central region includes an array of condensation ramps, each condensation ramp disposed along the crest of the thread between two circumferentially adjacent flute segments, each condensation ramp having a lower leading edge and a higher trailing edge in a rightward direction; the tip end has at least one cutting lip, the cutting lip having a generally radially extending edge formed between a plow surface and a buttress surface; Implant.

2. The implant of claim 1 , further comprising a valley disposed at the distal end, the valley transverse to the central axis.

3. The implant of claim 2 , wherein the valley extends substantially perpendicular to the plow surface.

4. The implant of claim 2 , wherein the valley has a substantially flat bottom.

5. The implant of claim 2 , wherein the valley has a generally axially extending sidewall.

6. The implant of claim 2 , wherein the at least one cutting lip comprises a pair of cutting lips, the pair of cutting lips being diametrically opposed to one another, and the valley separating the cutting lips.

7. The implant of claim 1 , wherein the plow surface is generally planar and the buttress surface is generally planar.

8. The implant of claim 7 , wherein the plow surface lies in a plane generally parallel to the central axis.

9. The implant of claim 1 , further comprising a microbevel disposed on the buttress surface adjacent the cutting lip.

10. 10. The implant of claim 1, further comprising a feed ramp positioned at a base of the plow face, the feed ramp bisecting at least one turn of the thread to form self-tapping teeth on the plow face.

11. The implant of claim 10 , wherein the feed ramp extends between one of the buttress surfaces and one of the plow surfaces.

12. 10. The implant of claim 1, wherein the thread has a thread thickness measured axially at the apex, the thread thickness being variable along the thread.

13. 13. The implant of claim 12, wherein the thread thickness is greater in the central region than in the apical and coronal regions.

14. 10. The implant of claim 1, wherein the crests of the threads are truncated and the threads have an offset measured radially from the roots to the crests.

15. 15. The implant of claim 14, wherein the thread has a leading flank disposed toward the apical region and a trailing flank disposed toward the coronal region, and wherein the offset on the leading flank of the thread is not equal to the offset on the trailing flank of the thread.

16. An implant of the type that is screwed into a hole prepared in raw bone, said implant comprising: a body extending longitudinally along a central axis between a distal end and a coronal end, the body having a distal region extending from the distal end, the body having a coronal region extending from the coronal end, a central region of the body disposed between the distal region and the coronal region; at least one thread projecting from the body and winding helically along continuous turns from the tip region to the coronal region, the thread having a crest, the thread having a leading flank disposed toward the tip region and a trailing flank disposed toward the coronal region, a portion of the body between adjacent turns of the thread including a valley, the valley spiraling helically along the body; Equipped with the body has a distal taper throughout the distal region, the distal taper being between about 2 and 30 degrees relative to the central axis; the body has a coronal taper throughout the coronal region, the coronal taper being between about 5 and 35 degrees relative to the central axis; the body has a central taper throughout the central region, the central taper being between about -5 and +15 degrees relative to the central axis; the central region includes an array of flutes, each flute extending longitudinally along the central region, each flute being comprised of a plurality of separate, isolated flute segments, the isolated flute segments being formed at the crests of the threads, each isolated flute segment within a flute being circumferentially offset from the next adjacent isolated flute segment to form a helical twist, the helical twist being left-handed; the central region includes an array of condensation ramps, each condensation ramp disposed along the crest of the thread between two circumferentially adjacent flute segments, each condensation ramp having a lower leading edge and a higher trailing edge in a rightward direction; the tip end has a pair of cutting lips, each having a generally radially extending edge formed between a plow surface and a buttress surface, the pair of cutting lips being diametrically opposed to one another; Implant.

17. 17. The implant of claim 16, further comprising a valley disposed at the distal end and separating the cutting lips, the valley transverse to the central axis, the valley extending generally perpendicular to the plow surface.

18. 17. The implant of claim 16, wherein the thread has a thread thickness measured axially at the apex, the thread thickness being variable along the thread, the thread thickness being greater in the central region than in the apical region and the crown region.

19. 17. The implant of claim 16, wherein the crest of the thread is truncated and the thread has an offset measured radially from the root to the crest, the offset on the leading flank of the thread not equal to the offset on the trailing flank of the thread.

20. An implant of the type that is screwed into a hole prepared in raw bone, said implant comprising: a body extending longitudinally along a central axis between a distal end and a coronal end, the body having a distal region extending from the distal end, the body having a distal taper throughout the distal region, the body having a coronal region extending from the coronal end, the body having a coronal taper throughout the coronal region, a central region of the body disposed between the distal region and the coronal region, the body having a central taper throughout the central region; at least one thread projecting from the body and winding helically along continuous turns from the distal region to the coronal region, the thread having a pitch that is variable along the length of the body, the thread having a leading flank disposed toward the distal region and the thread having a trailing flank disposed toward the coronal region, a portion of the body between adjacent turns of the thread including a valley, the valley having a generally flat surface that spirals along the body, the generally flat surface being generally parallel to the central axis; Equipped with the thread has a truncated crest, the thread has an offset measured radially from the root to the crest, the offset on the leading flank of the thread not equal to the offset on the trailing flank of the thread; the thread has a thread thickness measured axially at the apex, the thread thickness being variable along the thread, the thread thickness being greater in the central region than in the tip region and the crown region; the central region includes an array of flutes, each flute extending longitudinally along the central region, each flute being comprised of a plurality of separate, isolated flute segments, the isolated flute segments being formed at the crests of the threads, each isolated flute segment within a flute being circumferentially offset from the next adjacent isolated flute segment to form a helical twist, the helical twist being left-handed; the central region includes an array of condensation ramps, each condensation ramp disposed along the crest of the thread between two circumferentially adjacent flute segments, each condensation ramp having a lower leading edge and a higher trailing edge in a rightward direction; the tip end has a pair of cutting lips diametrically opposed to one another, each cutting lip having a generally radially extending edge formed between a plow surface and a buttress surface, the plow surface being generally parallel to the central axis, and a microbevel disposed on the buttress surface adjacent the edge; a valley disposed at the tip end, the valley transverse to the central axis, the valley extending generally perpendicular to the plow face, the valley separating the cutting lips; Implant.

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