Bone conditioning implant

Abstract

An implant for screwing into a prepared hole in live bone has a body that extends between apical and coronal ends. A thread winds helically along the body. The thread has a truncated crest, in which are formed many flute segments that in combination establish an array of flutes. The truncated crest also supports an array of condensing ramps that are configured to apply compressive strain to the interior surface of the hole with a densifying action while the implant is screwed into the hole. The apical end has a pair of cutting lips that are diametrically opposed from one another. Each cutting lip is formed between a plowing face and a buttressing face. A micro-bevel is disposed on the buttressing face adjacent the cutting lip. A valley is disposed in the apical end. The valley enables formation of a generally circular stub at the base of the hole.

Description

BONE CONDITIONING IMPLANTCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to US Provisional Patent Application numbers 63 / 489,233 filed on March 9, 2023 and 63 / 498,444 filed on April 26, 2023, the entire disclosures of which are hereby incorporated by reference and relied upon.BACKGROUND OF THE INVENTION

[0002] Field of the Invention. The invention relates generally to implants intended to provide fixation in a host material, and more particularly to implants designed to provoke new bone ingrowth and osseointegration and improve stability, and even more particularly to such implants placed in living organic materials like bone.

[0003] Description of Related Art. Screw-in implants are used in many applications. For example, in industrial and construction settings, where the host material is wood or concrete or metal or polymer, an implant may be placed to provide a fixed point of connection to attach another element. Screw-in implants are used extensively in medical applications, where the host material is bone, to provide a fixed point of connection for metal plates, pins, rods, Kirschner wires and intramedullar}' devices such as the Kiintscher nail and interlocking nail, among many other uses.

[0004] Dental implants are another form of screw-in implant where the host material is bone. A dental implant, also known as an endosteal implant or fixture, is a surgical device used to support a crown, bridge of teeth, denture, facial prosthetic or to act as an orthodontic implant. Typically, such implants are designed as threaded, tapered implants that could be loaded immediately after setting in order that full stability (i.e., secondary stability) may be reached over time as the surrounding bone grows into the crevices of and around the implant - a process known as osseointegration. Several months may be required for bone ingrowth until the implant reaches enough (secondary) stability to be put into normal loading service.

[0005] In many applications, implant stability is a key consideration because the implant must be able to support the intended loading. When the host material is not organic living tissue (such as in the case of foams and metals), maximum implant stability is usually achieved immediately after placement. For 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 living material, like bone or wood, reaching full implant stability may require thepassage of time for healing and in-growth after placement. In these latter cases, the more quickly an implant can reach an adequate level of secondary stability, the better.

[0006] Implants that possess an adequate level of stability at the time of initial placement are highly valued. Although the prior art is composed of a great many different designs and concepts aimed at improving implant stability - both primary (initial) and secondary (longterm) - there remains a continuing desire for improvement. Specifically, implant stability remains a long-felt need in the art where improvements are readily embraced. Moreover, there is a need for an improved implant that can facilitate osseointegration at the leading (apical) tip.BRIEF SUMMARY OF THE INVENTION

[0007] According to an embodiment of this invention. An implant is provided of the type screwed into a prepared hole. The implant comprises a body that extends longitudinally along a central axis between an apical end and a coronal end. The body has an apical region that extends from the apical end, and a coronal region that extends from the coronal end. A central region of the body is disposed between the apical region and the coronal region. At least one thread protrudes from the body and winds helically there along in continuous turns from the apical region to the coronal region. The thread has a crest. The portion of the body between adjacent turns of the thread comprises a root. The central region includes an array of flutes. Each flute extends longitudinally along the central region, and is composed of a plurality of distinct and isolated flute segments. The isolated flute segments are formed in the crest of the thread. The central region includes an array of condensing ramps. Each condensing ramp is disposed along the crest of the thread between two circumferentially- adjacent flute segments. Each condensing ramp has a low leading edge and a high trialing edge in the right-hand direction. The apical end has at least one cutting lip. The cutting lip has a generally radially extending edge formed between a plowing face and a buttressing face.

[0008] The unique shape of the apical end with a cutting lip enables the implant to scrape and cut host material as the implant is screwed into the prepared hole. The particles of host material (e.g., bone debris) liberated by the cutting lips accumulate around the apical end as it descends toward the hole bottom. These dislodged bone chips behave as seeds for bone growth accelerant, thus facilitating new bone ingrowth and osseointegration. The multi-faceted shape of the apical end significantly increases the surface area of bone-to-implant contacts and thus improves stability.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0009] These and other features and advantages of the present invention will become more readily appreciated when considered in connection with the following detailed description and appended drawings, wherein:

[0010] Figure 1 is a cross-section though a human mandible with an implant according to one embodiment of this invention fully seated;

[0011] Figure 2 is an elevation view of the implant of Figure 1 ;

[0012] Figure 3 is a view as in Figure 2 but emphasizing various tapers of the body / root as well as the taper of the thread crests;

[0013] Figure 4 is a fragmentary view of the implant of Figure 2 but emphasizing the offsets between thread crest and intervening root;

[0014] Figure 5 is a view as in Figure 4 but emphasizing the thread thicknesses and the thread pitch;

[0015] Figure 6 is an apical end view of the implant of Figure 2;

[0016] Figure 7 is a perspective view of the apical end;

[0017] Figure 8 is another perspective view of the apical end presented from a slightly different perspective from that of Figure 7 ;

[0018] Figure 9 shows the implant of Figure 2 partially inserted into a prepared hole;

[0019] Figure 10 is a view as in Figure 9 but showing the implant fully seated in the prepared hole;

[0020] Figure 11 is an enlarged view of the area circumscribed at 11 in Figure 10;

[0021] Figure 12 is an elevation view of the implant according to an alternative embodiment;

[0022] Figure 13 is a fragmentary perspective view of the apical end of alternative implant of Figure 12;

[0023] Figure 14 is a full perspective view of the alternative implant of Figure 12; and

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

[0025] Referring to the figures, wherein like numerals indicate like or corresponding parts throughout the several views, the invention is described in the context of a dental implant, in which preparation of an osteotomy in a jaw bone is required to receive a bone implant (Figure 1). It will be understood that this invention is not limited to dental applications but may be applied across a wide spectrum of orthopedic applications. Furthermore, the invention is not limited to use in bone. This invention may be used to provide an implant in living trees and other live cellular materials, as well as in metal foams and other non-living cellular hostmaterials used for various industrial and commercial applications, to name but a few. Nevertheless, dental applications represent a convenient example, such that the following description will make use of the dental context with bone as the host material for illustrative purposes.

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

[0027] The prepared hole, or osteotomy, can be formed using any suitable technique. One such technique comprises the use of progressively wider rotary osteotomes specially configured to achieve osseodensification along the surrounding bone walls. The procedure of forming an osteotomy using progressively wider rotary osteotomes is described, generally, in US 9,326,778 to Huwais, issued May 3, 2016. Reference may also be had to US 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 osteotomy has been prepared, again by any suitable technique, the implant 20 is screwed into place as illustrated in Figure 1, by turning in the customary right-hand direction. According to well-known practices, an abutment (not shown) is eventually threaded into an internal connection and is thereby secured in position to receive a subsequent restoration or crown (also not shown). The implant 20 is perhaps ideally suited for placement in bone, yet non-bone applications are possible. To say again, although the illustrated embodiments depict the implant 20 in the form of an implant or receptor for a dental restoration, it must be appreciated that the implant 20 may be re-configured as a bone screw or other bone fixation element as may be used for example in spinal, hip, shoulder, wrist and other orthopedic applications, as well as an implant for a variety of non-medical applications.

[0029] The implant 20 can be designed to fit in a prepared hole of different diameters. Implants 20 of differing lengths and diameters suited for prepared holes of different depths and diameters are likewise possible, although not depicted. Those of skill in the art will appreciate that the principles of this invention can take many different forms without departing from the spirit of the teachings. With this understanding, the invention will be described in the context of the generic example depicted in Figures 2-11.

[0030] Referring specifically to Figures 2 and 3, the implant 20 comprises a truncated body formed with a tapered outer profile. The body of the 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 association. “Apical” means adirection toward the root tip(s) of a tooth; “coronal” means a direction toward the crown of a tooth. Applicant’s use of these terms and perhaps others herein must not be construed so as to limit the application of the implant 20 to the dental fields of use, or even to a medical field of use. The coronal end 24 is preferably flat, or substantially flat, and serves as a platform for a dental restoration or other subsequent attachment to the implant 20. The apical end 22 forms the leading end of the implant 20 and in use is inserted first into the prepared osteotomy. The apical end 22 includes several unique features and will be described with particularity below.

[0031] The implant 20 has an apical region 26 adjacent the apical end 22, and a coronal region 28 adjacent the coronal end 24. The apical region 26 represents a portion of the body that extends from the apical end 22. And likewise, the coronal region 28 represents a portion of the body that extends 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, on either end, to the apical 26 and coronal 28 regions such that these three regions 26, 28, 30 fully occupy the entire longitudinal length of the body, from apical end 22 to coronal end 24, in the illustrated examples.

[0032] In Figure 3 the outermost surface of the body can be easily discerned as having a tapered profile. In particular, the various regions 26, 28, 30 can be distinguished from one another by, among other things, the characteristics of the body taper. It therefore makes sense to describe the body as having an apical taper Ri throughout the apical region 26, a coronal taper R3 throughout the coronel region 28, and a central taper R2 throughout the central region 30.

[0033] The apical taper Ri may be between about 2°-30° measured from the central axis A. In some embodiments, the apical taper Ri may be between 7°-18°. The illustrated examples depict apical tapers Ri in the range of 10°-15°. By specifying that the taper angle is measured from the central axis A, it will be understood that this is a half-angle; the full conical taper will be double the given measures.

[0034] The central taper R2 may be between about -5° to +15° measured from the central axis A. As can be appreciated from the negative lower limit of the stated range, it is contemplated that the central taper R2 could possibly be formed with a reverse taper. However, in most embodiments it is expected that the lowermost limit of the central taper R2 will be nonnegative, as in a more limited range of about 0°-10°. The illustrated examples depict central taper R2 in the range of 0°-5°.

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

[0036] In bone applications these ranges may represent critical boundaries, in that failure to observe the range limits could result in too little radial compression or too much radial compression. It is not necessary that the apical Ri and R3 coronal tapers be substantially equal, i.e., matched to one another. For some dental applications and some non-dental orthopedic applications, somewhat larger taper ranges may be desired. For non-medical applications, still larger taper ranges may be considered.

[0037] In practice, the longitudinal lengths of the apical region 26, coronal region 28 and central region 30 can vary relative to the entire longitudinal length of the body and the relative taper angles Ri, R2 and R3. For example, in the illustrated embodiments, if the longitudinal length of the apical region 26 is designated as one unit, the central region 30 is about 1 ¥3 units in length and the coronal region 28 is about 1% units. By these rough measures, the entire longitudinal length of the body is thus just over 4 units. Naturally, the relative lengths of the apical region 26, coronal region 28 and central region 30 are highly adaptable to suit the intended application. That is to say, these dimensional relationships can be altered to suit the application and / or to achieve specific performance attributes. For example, the apical region 26 could be lengthened or shortened in relative terms; the coronal region 28 could be lengthened or shortened in relative terms, and the central region 30 could be lengthened or shortened in relative terms. Of course, many still further alternatives will become apparent to the skilled person in these arts. Notwithstanding the variable relative lengths, the outer form of the body should maintain a generally conical taper (i.e., Ri , R2, R3) that, on average, enlarges toward the coronal end 24. A conical geometry is believed to support superior primary stability and loading protocols. However, the invention can be practiced in true straight and nearly straight implant geometries with an expectation of success. Therefore, the principles of this invention are not limited to implant designs having only a conical geometry.

[0038] An internal tool socket is disposed in the body, opening directly from the coronal end 24 as is well-known in the art. The tool socket may extend through the coronal region 30 and well into the central region 30. The tool socket may be in the form of a hex-point receptacle for coupling with a complimentary- shaped driver head. Of course, the form of the tool socket will be matched to the application and the standards of the relevant industry / field of use. The tool socket is formed as a pass-through feature enabling access to a recessed threaded section. The threaded section is adapted to connect with an abutment or other feature to be subsequently attached to the implanted implant 20.

[0039] As shown throughout the several views, at least one thread 32 protrudes from the body. The phrase “at least one’’ is used to underscore that in some contemplated embodiments the implant 20 may be configured with double-lead or even triple-lead threads 32. However, in the illustrated examples the thread 32 is comprised of a single lead that winds helically incontinuous turns from the apical region 26, through the entirety of the central region 30, and well into the coronal region 28. In most contemplated applications, the thread 32 will wind about the body in the right-hand direction according to most common conventions. Of course, if a particular application were to dictate a preference for left-hand windings, a complete mirror image of the implant 20 would be expected to perform with similar functionality.

[0040] The thread 32 has a crest 34 at the apex of its leading and trailing flanks, as is common with thread fasteners and threaded mechanisms in general. For the sake of clarity, the leading flank is the helical surface of the thread 32 that faces toward the apical end 22, whereas the trailing flank is the helical surface of the thread 32 that faces toward the coronal end 24. If the leading and trailing flanks of the thread 32 were extended fully, they would meet in a sharp edge creating a blade-like crest. In this case, however, the crest 34 is truncated, or flatted. In the illustrated examples the crest 34 has a thickness that can be measured at any point there along in the axial or longitudinal direction. As will be described subsequently in connection with Figure 5, the thickness of the crest 34 can be configured to provide active functionality and novel attributes to the implant 20.

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

[0042] According to standard screw thread nomenclature, the thread 32 can be seen having a minor diameter that is 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 a root. The minor diameter corresponds to the root diameter of the thread 32. Referring now to Figure 4, at any point along the thread 32, the difference between the minor diameter and the major diameter can be measured as an offset 36 between the crest 52 and root or body of the implant 20. In Figure 4, the offsets 36 are indicated as a group rather than individually by broken lines and vectors. Thus, along the winding path of the thread 32, its offset 36 can be measured radially from the crest 34 to the root. Careful observation will reveal that at any point along the thread 32, in most cases the offset 36 on the trailing flank side is not equal, i.e., is unequal, to the offset 36 on the leading flank side.

[0043] As previously mentioned, the thread 32 has a thread thickness. The thread thickness is the axial dimension between leading and trailing flanks as measured at the crest 34. The thread thickness may be variable along the entire length of the thread 32, or at least variable along a portion of its length. Figure 5 shows that the thread thickness may be greater in the central region 30 and thinner in the apical 26 and coronal 28 regions. It is believed that avariable thread thickness that is greater in the central region 30 than in the apical 26 and coronal 28 regions can offer certain advantages as will be described below.

[0044] Moreover, the center point of each crest 34 can be used to determine the thread pitch. In Figure 5, the pitch of the thread 32 is discerned from the indicated center points. The pitch can be any suitable low angle. In some contemplated embodiments, the pitch will be generally constant along the length of the body. However, in the illustrated examples, the pitch varies. From Figure 5 it can be observed that the pitch in the apical region 26 grows or stretches slightly upon entering the central region 30. And then the pitch reduces or shortens slightly as it reaches the coronal end 24.

[0045] The root between turns of the thread 32 remains generally parallel to the central axis A as it winds helically along the body. The axial length of the root between turns of the thread 32 is generally equivalent along the length of the body. At any point along the thread 32, the axial length of the root will be generally the same. Notably, even though thread thickness 38 changes, the axial length of the root remains generally constant in the illustrated examples.

[0046] The combined effects of the unequal offsets 36 (trailing flank side vs. leading flank side), the changing thread thicknesses and the gently varying thread pitch, together with a generally constant axial length of the root, work together upon insertion into living host material such as bone by alternately compressing and expanding the cellular structure. In the case of bone and other living tissues, this cyclic compressing and expanding action activates the natural healing responses to promote regeneration and ingrowth. These, in turn, quickly produce long term stability for 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 Figure 6 shows an embodiment in which eight flutes 40 are formed on the implant 20. Regardless of the number of flutes, it is preferable that the flutes 40 are equally spaced from one another in the circumferential direction. In the example where an implant 20 includes eight flutes (e.g., Figure 6), each flute 40 will be circumferentially offset from the next adjacent flute by 45°. Each flute 40 extends longitudinally along the length of the central region 30, as perhaps best seen in Figure 2. That is, the flutes 40 are primarily confined to the central region 30; except for some limited encroachments the flutes 40 do not extend appreciably into either of the apical 26 or coronal 28 regions in the examples depicted in the figures. In other contemplated embodiments (not shown), the flutes can traverse substantially and / or fully either one or both of the apical 26 and coronal 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 and isolated flute segments separated from one another by the gap between windings in the thread 32. Each isolated flutesegment is formed as a scallop in the crest 34 of the thread 32. That is to say, each flute 40 is actually formed by an alignment of several stand-alone flute segments perhaps liked to a walking path that is formed by a series of individual but spaced-apart stepping-stones. The space or gap between turns of the thread 32 intersects the flutes 40 with each revolution, thereby dividing each flute 40 into a sequence of segments which is easily appreciated from the end view of Figure 6. Thus, a collection of flute segments establishes a single flute 40. If it is assumed for convenience that each flute 40 is composed of an average of seven flute segments, and if the implant 20 has eight flutes 40, then the total number of flutes segments will be about fifty-six uniformly distributed about the exterior of the central region 30 of the implant 20. The flutes 40 have a beneficial effect of increasing the surface configuration to provide more bone to implant 20 contact, thereby leading to better stability.

[0049] Each isolated flute segment within a common flute 40 is circumferentially offset from the next adjacent isolated flute segment so as to form a helical twist. The helical twist is easily seen from Figures 2 and 6. (Helical flutes 40’ are also apparent in the alternative embodiment of Figure 14.) In an example, each flute segment may be circumferentially offset from the next adjacent isolated flute segment by -10°. In this case, the helical twist of each flute 40 would be -10°. The negative value of the helical twist (e.g., -10°) connotes a left-hand twist. That is, the flute 40 can be seen to run or propagate in a direction opposite to the rotation direction needed to screw the implant 20 into its prepared hole. Of course, the -10° twist is offered for an example; other degrees of twist are contemplated and within the scope of the invention.

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

[0051] An advantage of a left-hand twist in the flutes 40 is appreciated in the context of implant 20 removal. Most host materials, and especially in cases where the host material is live bone, will grow and / or swell into the flutes 40 after placement. This migration could be motivated by recovery (spring-back) in elastic and semi-elastic materials due to stresses introduced into the host material, and possibly also ingrowth in the case of living host materials like bone and live wood. Host material that enters 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 flute 40 which, because of the left-hand twist, will behave like mechanical impediments.

[0052] In the illustrated examples, each flute 40 has a generally constant flute depth and generally consistent flute width / span. That is to say, the size and shape of each flute segmentis generally the same. However, this is not a requirement. In some contemplated embodiments the flutes 40 could 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 condensing ramps 42 disposed along the crest 34 of the thread 32 between the flute segments. That is, the condensing ramps 42 are located on the crest 34 between adjacent neighboring flutes 40 within the central region 30. Each condensing ramp 42 has a low leading edge and a high trialing edge arranged in the righthand direction. That is to say, the adjectives “leading” and “trailing” are based on rotation of the implant 20 in a right-hand direction as when being screwed into a prepared hole. The low leading edge will precede the high tailing edge in rotation like a ramp or wedge. Further details about the condensing ramps 42 may be found in the PCT Patent Publication No. W02020086611A1, the entire disclosure of which is incorporated herein by reference, and relied upon, in jurisdictions that recognize incorporation by reference.

[0054] Each condensing ramp 42 is configured to apply a localized compressive strain to the interior surface of the host material with a densifying action while the implant 20 is screwed into the prepared hole. More specifically, the helical strip of the host material that rubs against the thread crest 34 will be directly affected by the condensing ramps 42. Whereas, regions of the host material that do not rub against the crest 34, i.e., along the gaps between the thread 32, will not be directly affected by the condensing ramps 42. As the condensing ramps 42 drag across a portion of the interior surface of the hole, they produce localized areas of highly agitated, highly compressed bone (or other host) material, which may be referred to as superactivated zones. The condensing ramps 42 also induce stresses in the surrounding host material by the wiping action of the condensing ramps 42. It will be appreciated that placement of the implant 20 will cause a helical strip of host material to be super-activated by the condensing ramps 42 while an intervening helical strip of the host material is substantially less stressed. One can imagine that the helical strip of super-activated host material will lay along the course of the embedded thread 32, whereas the helical strip of less stressed host material will fill the cavity between the thread 32. As a consequence, a double-helix of super-activated and less stressed host material is generated in the walls of the hole by the action of screwing the implant 20 into position.

[0055] Almost immediately, the living host material will begin filling the voids of the flutes 40. Induced stresses that are within the host material’s ability to deform elastically will reverse themselves as reaction forces and promptly return toward the un-deformed condition once the stress is removed. The reaction forces will thus cause the surrounding bone or host material to spring-back into the voids of the flutes 40. The effect will be that of the host material constricting about the implant 20 and flowing into the flutes 40.

[0056] The scallops in the crest 34 of the thread 32 provide spaces to receive bone that is springing back toward a previous shape. This phenomenon enables the flutes 40 to be understood as healing chambers. That is to say, the healing chambers will effectively draw in the bone (or another host material). The healing chambers serve as incubator sites to rapidly achieve secondary stability. The healing chambers encourage and promote the inflow of bone to fill the voids.

[0057] In living host materials, e.g., bone, when the induced stresses exceed the bone’s ability to deform elastically, the bone will change shape permanently by plastic deformation. In bone, the permanent change in shape may be associated with micro-cracks that allow energy release, a compromise that is a natural defense against complete fracture. Micro-cracks are believed to produce blood flow, which in turn leads to clots forming in the voids of the flutes 40. All of this agitation activates the bone’s natural healing properties leading to rapid growth of new bone into the flutes 40. Thus, the super- activated zones promote the natural healing properties in the human body to accelerate recovery and improve osseointegration, especially into the healing chambers formed where each flute segment comes to rest once the implant 20 is fully seated.

[0058] Over time a strong, dense layer of new bone growth surrounds the implant 20, spurred by the combination of super-activated zones and reaction forces. The healing chambers fill with solid new bone that lock the implant 20 in place. Earlier, it was estimated that the illustrated implant 20 may have approximately fifty-six flute segments in total. That means fifty-six discrete healing chambers, evenly distributed about the entire external central region 30, incubate new bone growth and accelerate the osseointegration process. This wide and even distribution of isolated healing chambers super- accelerates the healing process while almost immediately mechanically locking the implants 20 in place.

[0059] The host material trapped in the gap between turns of the thread 32 is disturbed to a substantially lesser degree as the implant 20 is screwed into position. The generally constant axial root length means that the section of host material between turns of the thread 32 will not have been directly interrupted to the same degree while installing the implant 20. In contrast, the helical band of host material engaged by the crest 34 of the thread 32 is highly agitated and disturbed by screwing the implant 20 into place due to the condensing ramps 42. This highly agitated and disturbed band of host material does not directly affect the host material located in the gap between turns of the thread 32. As a result, the natural structural integrity of the host material remains largely intact in the gap between turns of the thread 32.

[0060] The host material trapped in the gap between turns of the thread 32 can be referred to as a controlled compression zone. The controlled compression zone is the helical band of host material between the body of the implant 20 (i.e., the root of the thread 32) and the crest 34 ofthe thread 32, from apical end 22 to coronal end 24. This controlled compression zone can be designed to manage the effects on the host material. Considering again Figure 4, in the apical region 26, the controlled compression zone gently and progressively displaces the host material, both at the root and crest 34 of the thread 32. This is represented by the differential between the minor diameter and the major diameter of the thread 32, i.e. , the varying rate of change of offsets 36 along the length of the implant 20. As the rate of change in the offset 36 decreases, i.e., the relative lengths of the broken line vectors in Fig. 4, the relative displacement of host material changes in the helical band affected by the crest 34 of the thread 32 also decreases. In relative terms, although both the root and crest 34 of the thread 32 are pushing the host material outwardly in the apical region 26 of the controlled compression zone, the action of the crest 34 will diminish.

[0061] In general, the condensing ramps 42 follow the same twist orientation as the flutes. Thus, in cases where the flutes 40 have a left-hand twist, the condensing ramps 42 will likewise have a left-hand twist. The condensing ramps 42 have a wiping or scraping effect on the interior surfaces of the prepared hole. The left-hand twist of the condensing ramps 42 gives each an oblique tilt that naturally imparts an axially outward stress on the walls of the hole as well as on any host slurry (e.g., bone particles mixed with fluids). By saying “axially outward” is it meant that a component of the directional stress is away from the bottom of the prepared hole and toward its opening. I.e., in an upward direction as viewed from Figures 1, 9 & 10.

[0062] In the central region 30 of the controlled compression zone, both the root and crest 34 of the thread 32 are pushing the host material outwardly at about the same rate as seen by considering the relatively equal central taper R2 and crest taper C in Figure 3. Thus, the apical region 26 initiates an unequal relative displacement of the controlled compression zone and super- activated zones affected by the crest 34, but throughout the central region 30 the continued displacement of host material is relatively equal. Entering the coronal region 28 of the controlled compression zone once again experience unequal relative displacement vis-a-vis the super- activated zones. One purpose of this configuration is to modulate, in a massage-like manner, the radial stresses in the host material. In human bone, for example, a hard layer of cortical bone typically lays on the surface with soft cancellous bone on the interior. See Figure 1. By modulating the radial stresses in the area of the hard cortical bone, stress fractures are less likely to develop around the implanted implant 20.

[0063] This modulating action can induce certain favorable preconditioning effects - namely an initial gentle compression of the bone particles displaced either by the root of the implant or by the crest 34 of the thread 32. It should be noted that the bone particles affected by the preconditioning effects of the implant 20 can either be autografted particles of live bone, native live bone particles or a mixture of both. In any case, the preconditioning effects will activateand energize the live bone and bone particles. The modulated stress on the bone particles will enable some shifting of particles and alignment of microcracks that will have formed during the initial hole formation process. As a consequence, a substantial portion of the sidewalls of the osteotomy have been coldworked back and forth, provoking the affected bone particles into rapid healing and osseointegration with the implant 20.

[0064] When an implant 20 is initially placed, the host material trapped in the gap between turns of the thread 32, i.e., the so-called controlled compression zone, serves to provide a favorably high level of initial, or primary, stability to the implant 20. During these moments and days following placement of the implant 20, the healing chambers have not had adequate time to fill and achieve osseointegration. It is during this stage that the host material in the gap between turns of the thread 32 primarily secures the implant 20 in position. Once sufficient time is allotted for new bone growth via the super-activated zones and healing chambers, the new bone growth provides substantial enhanced secondary stability for the implant 20 that enables full loading under all normal conditions.

[0065] The apical end 22 is defined by at least one, but preferably a pair of cutting lips 44. The cutting lips 44 are in fact edges that are disposed on opposite sides of the apical end 22. In such cases where there are a pair of cutting lips 44, the edges may or may not lie within a common plane passing through the central axis A. In the illustrated embodiment of Figure 6, it can be observed that the cutting lips 44 do not lie within a common plane. Rather, the cutting lips 44 are in this example slightly laterally offset (in terms of a direct diametrical alignment) by the short span on opposite sides of the central axis A. To maintain balance and symmetry, it is to advantage that the pair of cutting lips 44 are arranged so as to be diametrically opposed from one another, even if not co-planar.

[0066] The afore mentioned edge of each cutting lip 44 extends in a generally radial direction. Considering the example of Figure 6 in which the respective edges are offset from the central axis A, it is understood that these edges nevertheless extend in a mostly or predominantly radial direction albeit not truly along radials emanating from the central axis A. Even a somewhat radial extension of the edges could be implemented with the expectation of success. Each edge is formed between a plowing face 46 and a buttressing face 48. The plowing face 46 may be curved or planar depending on the fabrication technique used and the designer’s choice. In the illustrated examples. The plowing face 46 is generally planar, and set in a plane that is generally parallel to the central axis A. The buttressing face 48 also may be curved or planar. In the illustrated examples, the buttressing face 48 is generally planar.

[0067] In Figures 6-8, it can be observed that each cutting lip 44 has a generally planar microbevel 50; it being understood that the micro-bevels 50 are optional. That is to say, a microbevel 50 may be added to the buttressing face 48, adjacent the edge, but the implant 20 canalso function acceptably without the micro-bevels 50. The micro-bevel 50 creates a secondary bevel with respect to the primary bevel established by the buttressing face 48. The microbevels 50 may improve the cutting performance of the cutting lips 44 because they are canted from their respective cutting lips 44 at a micro-bevel angle. The micro-bevel angle may be varied between about 25° and 60° to optimize performance and durability for the application. In practice, the micro-bevel angle may be approximately 45° measured as a plane relative to the central axis A. In the illustrated examples where the plowing faces 46 are parallel to the central axis A, the same measure would be seen if the micro-bevel angle measurement is taken directly between the intersecting plowing face 46 and micro-bevel 50. It will be appreciated that the two opposing micro-bevels 50 are set in opposite directions so that when the implant 20 is screwed into position, the micro-bevels 50 follow their respective cutting lips 44. In this configuration, the implant 20 naturally turns in a cutting direction where the cutting lips 44 cut or slice bone at the base of the osteotomy. Or said another way, the cutting direction can be defined as rotationally sweeping the cutting lips 44 into the bone (or other host material in nonmedical applications).

[0068] Each buttressing face 48 is formed adjacent to, and falls away from, each micro-bevel 50 at a primary angle. The primary angle is smaller than the micro-bevel angle. In an example where the micro-bevels 50 are formed at 45° relative to the axis A, the buttressing faces 48 may be 40° or less. Typically, the difference between micro-bevel angle and primary angle is only a few degrees - often less than 10° difference.

[0069] In the examples shown, a feed ramp 52 is located at the base of the plowing face 46. The feed ramp 52 extends between a buttressing face 48 and a plowing face 46. In the illustrated examples, the feed ramp 52 is formed adjacent to, and falls away from, each buttressing face 48 at a tertiary angle. The tertiary angle is smaller than the primary angle. In the previous example where the buttressing faces 48 are formed at 40° relative to the axis A, the feed ramps 52 (i.e., the tertiary angle) may be 30° or less. Each feed ramp 52 is disposed in a sector of the apical end 22 between a buttressing face 48 and a cutting lip 44.

[0070] The feed ramps 52 have at least two functions. One such function is to form at least one self-tapping tooth, preferably a plurality of self-tapping teeth, in the plowing face 46. This is accomplished by the feed ramps 52 bisecting one or more turns of the thread 32, as visible in Figures 7&8. This produces one or more sharp teeth in the apical region 26 that will cut clearances for the thread 32 as it advances in the host material with a screwing motion. Another function of the feed ramps 52 will be described below in connection with Figure 10 & 12.

[0071] Some contemplated embodiments of the implant 20 may omit the feed ramp 52, by merely configuring and extending the buttressing faces 48 to adjoin the opposing plowing faces 46. In these cases, the buttressing faces 48 would perform the function of the feed ramps 52.

[0072] In the embodiment of Figures 1-8, the implant 20 is shown including a valley 54 disposed in the apical end 22. The valley 54 is depicted in these examples as short offset space between the cutting lips 44. That is to say, the apical end 22 of this embodiment is fashioned with a groove-like space or notch. The valley 54 is shown traversing the central axis A, and extending generally perpendicular to said plowing faces 46. Or said another way, the valley 54 extends generally perpendicular to the cutting lips 44, separating said cutting lips 44 from one another.

[0073] As can be observed in the side views of Figures 2 and 3, the valley 54 can have a generally flat bottom with generally axial sidewalls. However, other shapes for the valley 54 are contemplated, including a U-shaped cross-groove, a V-shaped cross-groove, as well as other configurations.

[0074] Figure 9 shows the implant 20 partially inserted into a prepared hole. As the implant 20 descends into the prepared hole by screwing action, the outermost edges of the cutting lips 44 will scrape and cut host materials and the self-tapping teeth will cut grooves for the thread 32, but the valley 54 has little-to-no interaction with the host material. The particles of host material (e.g., bone) generated by the cutting lips 44 and self-tapping teeth will accumulate around the apical end 22 as the apical end 22 descends toward the hole bottom.

[0075] Figure 10 shows the implant 20 after reaching final depth in the prepared hole. In most cases, the original bottom of the hole will be slightly shallower than the overall length of the implant 20. In such cases, i.e., when the implant 20 is longer than the prepared hole is deep, just prior to reaching full depth the cutting lips 44 will begin to scrape and cut against the base of the hole, cutting the bone and producing a quantity of bone debris 56. The bone chip-like debris 56 cut and lifted by the cutting lips 44 collects in the feed ramp 52, piled-up against the plowing face 46. These dislodged bone chips 56 behave as seeds of bone growth accelerant that facilitate new bone ingrowth and osseointegration.

[0076] A well-documented product of the osseodensification methods described in US 9,326,778 and US20190029695A1 is a layer of bone slurry along the sidewalls of the osteotomy and at its base. In fact, the quantity of bone slurry will typically be greatest at the base of the osteotomy. This bone slurry is very beneficial to the healing processes. Bone ingrowth and re-growth and osseointegration are all substantially enhanced and facilitated by this bone slurry derived from the osseodensification process. Toward this end, as the apical end 22 of the implant 20 enters this pool of bone slurry as shown in Figure 10, the bone slurry will be squeezed and begin to migrate in an upward direction (i.e., toward the coronal end 24).

[0077] As mentioned earlier, the condensing ramps 42 have a wiping or scraping effect on the interior surfaces of the prepared hole. The oblique tilts of the condensing ramps 42 naturally imparts an axially stress on the walls of the hole as well as on the slurry of boneparticles as the implant 20 is screwed into position, somewhat like impellers of a turbine pump. Under the influence of this imparted stress, bone slurry migrates as if pumped toward the open end of the hole by the combined effects of the condensing ramps 42 and the shrinking volume indicated by the offsets 36 in the apical region 26. When the migrating bone slurry is lifted into the central region 30, it can be appreciated from Figure 5 that the now increasing volumes indicated by the expanding offsets 36 in that central region 30 will help draw the bone slurry more rapidly toward the open end of the hole. That is to say, comparing the rate of change in the offsets 36 in the apical region 26 to those in the central region 30, it can be understood that any fluidic materials contained in those spaces will experience the effects of positive and negative pressurization as the implant 20 is screwed into place. In the central region 30, a relative vacuum of sorts will lift and pull the bone particles and bone slurry up from the base of the prepared hole. By actively distributing the bone slurry along the length of the implant 20, the aforementioned beneficial healing effects can be maximized. Bone slurry is thus drawn into the healing chambers distributed around the implant 20 where bone growth can occur in multiple dispersed sites.

[0078] To prevent the slurry from being over-drawn and exiting the hole, the coronal taper R3 is preferably larger than the central taper R2. In this manner, the coronal taper R3 can perform a corking function. That is, bone slurry that shifts toward the open end of the hole by the configuration of the offsets 36 in the apical 26 and central 30 regions will be blocked, or at least retarded, by the relatively large coronal taper R3. Ideally, little-to-none of the bone slurry will leak out of the prepared hole before the implant 20 is fully seated. In this manner, the novel shape of the implant 20 takes maximum advantage of the healing powers of the bone slurry, thereby shortening the healing time and improving the ultimate stability of the implant 20.

[0079] In the enlarged view of Figure 11, it can be seen that when the implant 20 is at final depth in the osteotomy, a quantity of bone debris 56 is piled-up against the plowing face 46 and within a 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 ramp 52 and valley 54 behave as bone growth accelerant to facilitate new bone ingrowth and osseointegration. However, because of the valley 54, the center section of the osteotomy base has been left relatively undisturbed by the implant 20. The undisturbed region is in the shape of a generally circular stub 58 because on the rotation of the cutting lips 44. The stub 58 is a stability-enhancing feature of the implant 20. The stub 58 acts as a self- locking point or short tenon of bone that seats within the valley 54 to further resist lateral displacement under loading. Moreover, the valley 54 significantly increases the surface area of the apical end 22 thus increasing the bone- to-implant contacts and resulting in greater stability.

[0080] The apical end 22 can be fashioned in a variety of ways that differ from design shown in Figures 1-11 having a valley 54. Some contemplated embodiments may employ a simple blunted or rounded shape for the apical end 22. Figures 12-15 depict 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 examples, here the cutting lips 44’ are edges that angle upwardly and outwardly (generally radially) from the apical end 22’. Each cutting lip 44’ is formed between a plowing face 46’ and a buttressing face 48’. A micro-bevel 50’ may be added to the buttressing face 48’ , adjacent the cutting lip 44’ . A feed ramp 52’ is located at the base of the plowing face 46’ and extends to an adjacent a buttressing face 48’.

[0081] As in the preceding examples, the outermost edges of the cutting lips 44’ scrape and cut host material and the self-tapping teeth cut grooves for the thread 32’ as the implant 20’ is screwed into the prepared hole. The particles of host material (e.g., bone debris 56’) liberated by the cutting lips 44’ and self-tapping teeth accumulate around the apical end 22’ as it descends toward the hole bottom. The bone debris 56’ collects in the feed ramp 52’, piled-up against the plowing face 46’. These dislodged bone chips 56’ behave as seeds of bone growth accelerant that facilitate new bone ingrowth and osseointegration. Although in this case there may not be a feature corresponding to the stub 58 of the previous embodiment, the multifaceted shape of the apical end 22’ nevertheless significantly increases the surface area of bone- to-implant contacts, thus resulting in great stability.

[0082] The foregoing invention has been described in accordance with the relevant legal standards, thus the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art and fall within the scope of the invention.

Claims

What is claimed is:

1. An implant of the type screwed into a prepared hole, said implant comprising: a body extending longitudinally along a central axis between an apical end and a coronal end, said body having an apical region extending from said apical end, said body having a coronal region extending from said coronal end, a central region of said body disposed between said apical region and said coronal region, at least one thread protruding from said body and winding helically there along in continuous turns from said apical region to said coronal region, said thread having a crest, the portion of said body between adjacent turns of said thread comprising a root, said central region including an array of flutes, each said flute extending longitudinally along said central region, each said flute being composed of a plurality of distinct and isolated flute segments, said isolated flute segments formed in said crest of said thread, said central region including an array of condensing ramps, each said condensing ramp disposed along said crest of said thread between two circumferentially-adjacent flute segments, each said condensing ramp having a low leading edge and a high trialing edge in the right-hand direction, said apical end having at least one cutting lip, said cutting lip having a generally radially extending edge formed between a plowing face and a buttressing face.

2. The implant of Claim 1, further including a valley disposed in said apical end, said valley traversing said central axis.

3. The implant of Claim 2, wherein said valley extends generally perpendicular to said plowing face.

4. The implant of Claim 2, wherein said valley has a generally flat bottom.

5. The implant of Claim 2, wherein said valley has generally axially extending sidewalls.

6. The implant of Claim 2, wherein said at least one cutting lip comprises a pair of cutting lips, said pair of cutting lips being diametrically opposed from one another, said valley separating said cutting lips.

7. The implant of Claim 1, wherein said plowing face is generally planar, and said buttressing face is generally planar.

8. The implant of Claim 7, wherein said plowing face being disposed in a plane generally parallel to said central axis.

9. The implant of Claim 1, further including a micro-bevel disposed on said buttressing face adjacent said cutting lip.

10. The implant of Claim 1, further including a feed ramp located at a base of said plowing face, said feed ramp bisecting at least one turn of said thread to form a self-tapping tooth in said plowing face.

11. The implant of Claim 10, wherein said feed ramp extends between one of said buttressing faces and one of said plowing faces.

12. The implant of Claim 1, wherein said thread has a thread thickness measured axially at said crest, said thread thickness being variable along said thread.

13. The implant of Claim 12, wherein said thread thickness being greater in said central region than in said apical and coronal regions.

14. The implant of Claim 1, wherein said crest of said thread is truncated, said thread having an offset measured radially from said root to said crest.

15. The implant of Claim 14, wherein said thread has a leading flank disposed toward said apical region and a trailing flank disposed toward said coronal region, said offset on said trailing flank side of said thread being unequal to said offset on said leading flank side of said thread.

6. An implant of the type screwed into a prepared hole in live bone, said implant comprising: a body extending longitudinally along a central axis between an apical end and a coronal end, said body having an apical region extending from said apical end, said body having a coronal region extending from said coronal end, a central region of said body disposed between said apical region and said coronal region, at least one thread protruding from said body and winding helically there along in a continuous turn from said apical region to said coronal region, said thread having a crest, said thread having a leading flank disposed toward said apical region and a trailing flank disposed toward said coronal region, the portion of said body between adjacent turns of said thread comprising a root, said root spiraling helically along said body, said body having an apical taper throughout said apical region, said apical taper being between about 2-30° relative to said central axis, said body having a coronal taper throughout said coronel region, said coronal taper being between about 5-35° relative to said central axis, said body having a central taper throughout said central region, said central taper being between about -5° to +15° relative to said central axis, said central region including an array of flutes, each said flute extending longitudinally along said central region, each said flute being composed of a plurality of distinct and isolated flute segments, said isolated flute segments formed in said crest of said thread, each said isolated flute segment within said flute being circumferentially offset from the next adjacent isolated flute segment to form a helical twist, said helical twist having a left-hand direction, said central region including an array of condensing ramps, each said condensing ramp disposed along said crest of said thread between two circumferentially-adjacent flute segments, each said condensing ramp having a low leading edge and a high trialing edge in the right-hand direction, and said apical end having a pair of cutting lips, each said cutting lip having a generally radially extending edge formed between a plowing face and a buttressing face, saidpair of cutting lips being diametrically opposed from one another.

17. The implant of Claim 16, further including a valley disposed in said apical end and separating said cutting lips, said valley traversing said central axis, said valley extending generally perpendicular to said plowing faces.

18. The implant of Claim 16, wherein said thread has a thread thickness measured axially at said crest, said thread thickness being variable along said thread, said thread thickness being greater in said central region than in said apical and coronal regions.

19. The implant of Claim 16, wherein said crest of said thread is truncated, said thread having an offset measured radially from said root to said crest, said offset on said trailing flank side of said thread being unequal to said offset on said leading flank side of said thread.

20. An implant of the type screwed into a prepared hole in live bone, said implant comprising: a body extending longitudinally along a central axis between an apical end and a coronal end, said body having an apical region extending from said apical end, said body having an apical taper throughout said apical region, said body having a coronal region extending from said coronal end, said body having a coronal taper throughout said coronel region, a central region of said body disposed between said apical region and said coronal region, said body having a central taper throughout said central region, at least one thread protruding from said body and winding helically there along in a continuous turn from said apical region to said coronal region, said thread having a pitch, said pitch being variable along the length of said body, said thread having a leading flank disposed toward said apical region, said thread having a trailing flank disposed toward said coronal region, the portion of said body between adjacent turns of said thread comprising a root, said root having a generally flat surface spiraling helically along said body, said generally flat surface being generally parallel to said central axis, said thread having a truncated crest, said thread having an offset measured radiallyfrom said root to said crest, said offset on said trailing flank side of said thread being unequal to said offset on said leading flank side of said thread, said thread having a thread thickness measured axially at said crest, said thread thickness being variable along said thread, said thread thickness being greater in said central region than in said apical and coronal regions, said central region including an array of flutes, each said flute extending longitudinally along said central region, each said flute being composed of a plurality of distinct and isolated flute segments, said isolated flute segments formed in said crest of said thread, each said isolated flute segment within said flute being circumferentially offset from the next adjacent isolated flute segment to form a helical twist, said helical twist having a left-hand direction, said central region including an array of condensing ramps, each said condensing ramp disposed along said crest of said thread between two circumferentially-adjacent flute segments, each said condensing ramp having a low leading edge and a high trialing edge in the right-hand direction, said apical end having a pair of cutting lips, said pair of cutting lips being diametrically-opposed from one another, each said cutting lip having a generally radially extending edge formed between a plowing face and a buttressing face, said plowing face being generally parallel to said central axis, a micro-bevel disposed on said buttressing face adjacent said edge, a valley disposed in said apical end, said valley traversing said central axis, said valley extending generally perpendicular to said plowing faces, said valley separating said cutting lips.

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