Rotary osteotome

Abstract

This invention discloses a rotary tool configured for high-speed clamping and / or cutting actions to enlarge an orifice. The tool has a body with a plurality of grooves formed around it. Each groove has a cutting surface on one side and a densifying surface on the other. A cutting edge between adjacent grooves establishes a substantially unbounded working edge along each cutting surface. These working edges are configured to produce increased bone density when the tool is operated in clamping mode. A transverse valley is formed at the apex of the body. This valley is a notch among the tooth tips that produce a plurality of secondary cutting / grinding edges, which facilitate the generation and uniform distribution of bone fragments. When the rotary bone chisel is withdrawn from an enlarged orifice, a small button-like portion of the bone fragment remains at the bottom of the orifice. This button-like residue promotes inward bone growth and osseointegration with a subsequently installed anchor.

Description

Technical Field

[0001] The present invention is generally related to a tool for preparing a hole to receive an implant or clamp, and more specifically, the present invention relates to a rotating bone chisel and a method thereunder for extending an osteotomy or hole in other materials to receive an implant or other anchoring device. Prior Technology

[0002] An implant system is a medical device manufactured to replace a missing biological structure, support a damaged biological structure, or enhance an existing biological structure. A bone implant system is a type of implant placed in the bone of a patient. Bone implants can be found throughout the human skeletal system, including (but not limited to) dental implants in the jaw for replacing a lost or damaged tooth, arthroscopic implants for replacing a damaged joint (such as in the hip and knee), and reinforcing implants installed to repair fractures and remedy other defects (such as vertebral screws for spinal stabilization, etc.). Implant placement typically requires hole preparation, and care should be taken to prevent bone burns or pressure necrosis. After allowing time for the implant to integrate into the bone or other host material, adequate healing will enable rehabilitation treatment or restoration of normal use, or placement of a restoration, brace, or other attachment feature.

[0003] Several known methods exist for forming a receiving hole for an implant. For example, since the early days of implantology, standard drills that look and function very much like drills designed for industrial drilling applications have been used to prepare osteotomies. These drill designs have proven adequately functional for dental and medical applications; however, they are clearly imperfect. Over time, implantation success rates have become satisfactory, but osteotomy preparation techniques remain lacking for various reasons. The standard drill design used in prior art dental and medical implants is designed to excavate a hole in the bone to create space for implant placement, much like a woodworking drill. The twisted or grooved shape of the standard drill effectively cuts bone but typically does not produce a clean, precise circumferential osteotomy. The osteotomy becomes elongated and elliptical due to the tremor, as the drill is a very aggressive tool. In cases where the osteotomy is not perfectly circular, the implant insertion torque can be reduced, leading to poor primary stability and potential lack of integration. Osteotomy performed by drilling into narrow bone locations can cause clefts in the cheeks or tongue, reduces initial stability, and may require an additional bone graft procedure, thereby increasing treatment costs and healing time.

[0004] Recently, a novel biomechanical bone preparation technique called "bone mineral density enhancement" has gained widespread recognition in the global dental community. The bone mineral density enhancement technique, pioneered by the applicant of this invention, is a high-speed rotational technique that preserves the main bone throughout the hole-forming process. Bone retention has been shown to increase implant stability and accelerate regenerative bone growth. In some cases, bone mineral density enhancement is now considered a preferred treatment standard. Examples of bone mineral density enhancement can be found in U.S. Patent No. 9,028,253, issued May 12, 2015; U.S. Patent No. 9,326,778, issued May 3, 2016; and PCT Publication No. WO 2020 / 210442, published October 15, 2020. The entire disclosure of these references is hereby incorporated by reference and is based on the information permitted by the jurisdiction of each country.

[0005] Generally, bone mineral density enhancement is a procedure that expands an osteotomy using a specially designed multi-groove rotating bone chisel. An example suitable for a rotating bone chisel is described in U.S. Patent No. 9,326,778, mentioned above. Rotating bone chisels for dental applications are sold under the name Densah® Burs by Versah, LLC, of ​​Jackson, Michigan USA, one of the applicants' licensees.

[0006] Unlike traditional drilling techniques, bone density enhancement does not excavate bone tissue. Specifically, bone tissue is simultaneously compressed and autologously transplanted in an outward expansion direction, somewhat similar to a traditional hammer-and-chisel technique but without the trauma and other limitations of that impact method. When rotated at high speed in a reverse, non-cutting direction with the aid of stable external irrigation, this rotating chisel forms a strong and dense layer of bone tissue along the osteotomy wall and base. This dense, compressed bone tissue provides a stronger force-expanding mechanism for the implant and promotes faster healing.

[0007] In short, an example from dental implantology can be used to illustrate the general principles of bone density enhancement techniques. First, a pilot hole is drilled using a standard medical-grade auger, tri-flute drill, or other drilling tool with a small diameter (e.g., 1.5 mm) to prepare the osteotomy site. (Of course, the size of the pilot hole and other characteristics of the operation will be specified for any given surgical application, whether inherently dental or non-dental.) The pilot hole is drilled to a predetermined depth. Using a rotating chisel designed for bone density enhancement, the surgeon decides whether to enlarge the pilot hole by densification or cutting, taking into account contextual factors such as bone stiffness, the final expected osteotomy / implant size, the local width of bone formation, and other relevant factors.

[0008] If the surgeon decides to enlarge the pre-section pilot hole by cutting, a specially designed rotary chisel is rotated at high speed in one cutting direction. For rotary chisels with diameters ranging from approximately 1.5 mm to 6 mm, high speed is typically defined as above 200 RPM. The rotary chisel is advanced into the pre-section pilot hole, usually accompanied by a gentle pumping motion and thorough irrigation. As it descends, the working edge of the rotary chisel cuts bone material into small fragments or particles that accumulate in the groove. If necessary, the bone particles are then discarded or collected / harvested for later use. Similarly, the osteotomy can be further enlarged by cutting (or densifying) with progressively larger rotary chisels in one or more subsequent surgeries.

[0009] If, instead of cutting, the surgeon prefers to enlarge the precursor pilot hole by densification, the same rotating chisel is used, but rotated at high speed in a non-cutting direction. If the rotating chisel is designed so that its cutting direction is clockwise (as is the case with most augers), then the non-cutting direction of the same rotating chisel will be counterclockwise. That is, the non-cutting or densification direction is opposite to the cutting direction. During densification, the surgeon advances the counter-rotating rotating chisel into the precursor pilot hole (or a precursor hole formed as described in one of the previous enlargement operations) while performing extensive irrigation. The surgeon needs to apply downward pressure to keep the working edge of the rotating chisel in contact with the bone surface inside the osteotomy, usually using the gentle bouncing motion mentioned above to regulate pressure and thereby avoid overheating and excessive strain on the bone tissue. The greater the force with which the surgeon pushes the rotating chisel into the osteotomy, the greater the lateral pressure (both mechanical and hydrodynamic effects achieved by simultaneous irrigation). Care should be taken to maintain alignment between the longitudinal axis of the rotating chisel and the bore of the osteotomy. Once the rotating chisel has reached the desired depth, the enlargement is complete. The osteotomy can then be further enlarged by one or more subsequent procedures using a gradually increasing size rotating chisel after a similar process.

[0010] Biomechanical, histological, and clinical histological validation studies of bone mineral density enhancement technology have concluded that bone mineral density enhancement promotes bone expansion, increases implant stability, and generates a densifying layer around the preparation site by compressing along the entire depth of osteotomy and autologous bone graft particles.

[0011] Although described to date in the context of medical applications, the same techniques can also be applied to non-bone materials. Some industrial applications (including those requiring the placement of helical anchors in other organic materials (such as wood) or in other inorganic materials (such as foams and porous compositions of polymers and / or metals) are acceptable to and benefit from the general principles of this technique.

[0012] Bone mineral density enhancement is a relatively new field. Like any emerging technology, as it matures, new and improved tools and techniques are expected. Furthermore, there is still a need to improve the efficiency and effectiveness of surgical procedures. Therefore, any improvements to bone mineral density enhancement tools and / or techniques are anticipated to advance the fundamental techniques and improve efficiency and efficacy. Summary of the Invention

[0013] According to a first aspect of the present invention, a rotary bone chisel is adapted to perform osteotomy with a bone density enhancement effect. The rotary bone chisel includes a handle establishing a longitudinal axis of rotation. The handle has an upper end and a lower end. A body extends axially from the lower end of the handle. The body has a apex located away from the handle. A plurality of grooves are disposed around the body. Each groove has a working edge. The apex has at least two drill bits arranged circumferentially around the longitudinal axis in at least one adjacent pair. These drill bits form primary cutting / grinding edges. A fragmentation control surface extends between the adjacent pairs of drill bits. A valley passes through the longitudinal axis and is located between the adjacent pairs of drill bits. The valley intersects at least a portion of the fragmentation control surface and establishes a plurality of secondary cutting / grinding edges at the intersection with the fragmentation control surface.

[0014] According to a second aspect of the present invention, a rotary bone chisel is adapted to perform osteotomy with a bone density enhancement effect. The rotary bone chisel includes a handle establishing a longitudinal axis of rotation. The handle has an upper end and a lower end. A body extends axially from the lower end of the handle. The body has a apex located away from the handle. A plurality of grooves are disposed around the body. Each groove has a working edge. The apex has at least two drill bits circumferentially arranged around the longitudinal axis in at least one adjacent pair. These drill bits form primary cutting / grinding edges. A fragmentation control surface extends between the adjacent pairs of drill bits. The fragmentation control surface includes at least one ventral flank extending from one of the drill bits in the adjacent pair. At least one valley passes through the longitudinal axis and simultaneously bisects the adjacent pair of drill bits. The valley has an upper oblique sidewall that cuts off a central portion of one of the drill bits in the adjacent pair. The valley establishes a plurality of secondary cutting / grinding edges at the interface of the ventral flank.

[0015] According to a third aspect of the present invention, a method is provided for enlarging a precursor hole to receive a screw-in clamp. The method includes the steps of: rotating a rotating bone chisel at greater than 200 RPM, positioning the rotating bone chisel on a smaller precursor hole. The precursor hole has an inner surface extending between a generally circular inlet and a closed bottom. The inner surface of the precursor hole has a conical tapering sidewall. The precursor hole is enlarged by forcefully pushing the rotating body to the bottom of the precursor hole, simultaneously autotransplanting bone fragment particles generated therefrom into the sidewalls of the enlarged hole. The enlargement step includes flushing the rotating bone chisel with an irrigation fluid. A snap-like portion of the bone fragment is formed at the bottom of the enlarged hole. The method ends by withdrawing the rotating bone chisel from the enlarged hole, while the snap-like portion of the bone fragment remains at the bottom of the enlarged hole.

[0016] The novel valley feature of this invention is a cut at the tip of the tooth that produces a button-like number of bone fragments or debris at the center of the osteotomy base. These remaining bone fragments provide bone growth promoters to facilitate inward growth of new bone and osseointegration of a subsequently installed anchor. Furthermore, the valley has a beneficial effect on the flow of bone particles from the surfaces at the tip into the grooves. Specifically, the valley allows for a more uniform distribution of fragments within the grooves, resulting in smoother operation of the bone chisel and less rotational imbalance. The valley, at its intersection with the fragment control surface, forms a secondary cutting / grinding edge that produces bone fragments more rapidly than previous designs that relied entirely on the primary cutting / grinding edge formed by the drill bit. The bone fragments are effectively carried away from the tip, thereby reducing the likelihood of thermally induced and / or pressure-induced damage to the bone particles. This novel feature of the invention produces bone fragments with less direct surface contact with the parietal bone, resulting in less vertical pressure on the surgeon advancing the tool and less trauma to the patient. This invention better protects the vitality and health of bone fragments, thereby promoting the efficacy of autologous transplantation. Simple Explanation of the Diagram

[0017] These and other features and advantages of the invention will become more readily apparent when considered in conjunction with the following detailed description and accompanying drawings, wherein:

[0018] Figure 1 illustrates an exemplary application of the invention in a toothless (toothless) jaw region during a procedure for forming an osteotomy to receive an implant, according to one embodiment of the invention, the procedure involving the use of a rotating bone chisel;

[0019] Figure 2 is a perspective view of a rotating bone chisel according to one embodiment of the present invention;

[0020] Figure 3 is a front view of the rotating bone chisel in Figure 2;

[0021] Figure 4 is a top view of the rotating bone chisel in Figure 2;

[0022] Figure 5 is a top view of a rotating bone chisel, roughly taken along line 5-5 of Figure 4;

[0023] Figure 6 is an enlarged view of the tip of a rotating bone chisel, taken from a first-person perspective;

[0024] Figure 7 is an enlarged view of the tip of a rotating bone chisel, taken from a second-person perspective;

[0025] Figure 8 is an enlarged view of the tip of a rotating bone chisel, taken from a third-person perspective;

[0026] Figure 9 is an enlarged view of the tip of a rotating bone chisel, taken from a fourth-person perspective;

[0027] Figure 10A shows a simplified view of the tip of a rotating bone chisel descending toward the base of an osteotomy.

[0028] Figure 10B shows a further development of Figure 10A, illustrating the contact between the tip of the rotating bone chisel and the base of the osteotomy.

[0029] Figure 11A is an enlarged view of one of the areas in Figure 10B circumscribed at 11A and including the accumulation and upward migration of drilling debris;

[0030] Figure 11B is a further development of Figure 11A, showing the tip of a rotating bone chisel being lifted away from the base of the osteotomy to leave a small button-like body of drill fragments at the base of the osteotomy;

[0031] Figure 12 is a top view of one alternative embodiment showing drill fragments migrating outward into several slots;

[0032] Figure 13 is a partial front view of one of the first alternative embodiments of a rotary bone chisel;

[0033] Figure 14 is a one-end view taken along line 14-14 of Figure 13;

[0034] Figure 15 is a partial front view of one of the second alternative embodiments of a rotary bone chisel; and

[0035] Figure 16 is a one-end view taken along line 16-16 of Figure 15. Implementation

[0036] Cross-reference to related applications This application claims priority to U.S. Provisional Patent Application No. 63 / 608,920, filed December 12, 2023, the entire contents of which are hereby incorporated by reference and are based on.

[0037] Referring to the figures, where the same numbers in several views indicate the same or corresponding parts, Figure 1 illustrates an example of a dental procedure receiving an implant (not shown). It should be understood that the invention is not limited to dental applications but can be applied across a wide range of orthodontic applications. Human applications are typical, but animal applications are equally reasonable and do not fall outside the scope of the invention. Furthermore, the invention is not limited to bone applications but can be used to create pores in living organic, non-living organic, and non-organic materials for a variety of applications. In Figure 1, after a fully formed osteotomy 20 (Figure 2) is performed in the manner previously described, a toothless (toothless) jaw region has been prepared to receive a screw-in implant (not shown) or other anchoring device. In this example, the osteotomy 20 is formed using a modified rotary bone chisel 22 according to the invention. The rotary bone chisel 22 is also referred to in the art as a drill, a drill bit, and a drill.

[0038] The surgeon locks or otherwise mounts the rotating bone chisel 22 into the drill motor (Figure 1) and sets the rotation direction to a non-cutting direction. In the example illustrated, this non-cutting direction is counterclockwise when viewed along the length of the bone chisel 22 from the connection point to the drill motor towards the tip of its leading tooth. The tip of the leading tooth is also referred to as the apex. Skilled technicians will understand how to reconfigure the bone chisel 22 so that its non-cutting rotation direction is instead clockwise. Although the surgeon may change the rotation speed of the bone chisel 22 as needed, experimental results indicate that high rotation speeds (i.e., greater than about 200 RPM) and torque settings between about 5 Ncm and about 80 Ncm will provide satisfactory results. For rotating bone chisels 22 with diameters ranging from about 1 mm to about 7 mm, any rotation above about 200 RPM is considered high speed. The upper limit for these relatively small diameter rotating bone chisels can reach about 2000 RPM. More preferably, rotational speeds between approximately 600 RPM and 1800 RPM and torque settings between approximately 20 Ncm and approximately 80 Ncm have been found to provide satisfactory results. More preferably, rotational speeds in the range of approximately 800 RPM to approximately 1500 RPM and torque settings of approximately 50 Ncm have provided satisfactory results. The speeds recommended herein apply to the context of exemplary dental applications. For large bone orthopedic applications (e.g., femur), relatively large-diameter rotating bone chisels 22, which may be greater than 7 mm and, due to tangential velocity considerations at the working edge, may require lower rotational speeds than those for rotating bone chisels 22 used for smaller bone applications. That is, as a guiding principle for large-diameter rotating bone chisels 22, it is advantageous to maintain the tangential velocity measured at the outer edge between approximately 0.02 m / s and approximately 0.6 m / s to generate the appropriate compression wave required for achieving bone density enhancement within the bone. A continuous flow of irrigation fluid is used throughout the procedure.

[0039] Turning to Figure 2, a bone chisel 22 comprising a handle 24 and a body 26 according to one embodiment of the present invention is shown. The handle 24 has an elongated cylindrical shaft that establishes a longitudinal axis of rotation for rotating the bone chisel 22. A drill motor engagement interface 28 is formed at the distal upper end of the shaft for connection to a standard drill motor. The specific configuration of the interface 28 may vary depending on the type of drill motor used, and in some cases may even be simply a collet clamping a smooth portion of its shaft. The body 26 engages at the lower end of the handle 24, and this engagement may form a tapered or dome-shaped transition 30. The transition 30 acts like an umbrella when the surgeon irrigates with water during an operation. As the bone chisel 22 spins, the gentle transition 30 facilitates the flow of irrigation fluid to the osteotomy site.

[0040] The body 26 preferably has a tapered profile that decreases from a maximum diameter adjacent to the shank 24 and transition 30 to a minimum diameter adjacent to a tip 32. However, in some intended embodiments, the body may be non-tapered (i.e., cylindrical). Therefore, the tip 32 is located away from the shank 24. The working or effective length of the body 26 is related to its intended application and the taper angle of the body 26. Depending on the application, taper angles between about 1° and about 10° (or greater) are feasible. In many cases, the taper angle will be between about 1.5° and about 5°. More preferably, when the length of the body 26 is between about 11 mm and about 15 mm, a taper angle between about 2° and about 3° will provide satisfactory results for dental applications.

[0041] The tip 32 is defined by at least two, but likely more, drill bits 34. The drill bits 34 are, in fact, edges circumferentially arranged around the longitudinal axis in adjacent pairs. The drill bits 34 form primary cutting / grinding edges at the tip 32 of the chisel 22. In the example illustrated, cutting occurs when the chisel 22 rotates in a cutting direction and grinding occurs when the chisel 22 rotates in a non-cutting or compression direction. However, the tip 32 can be configured such that the drill bits 34 will be configured to grind in the cutting direction and cut in the compression direction, because the cutting and non-cutting directions are defined by the groove / working edge (described below) rather than by the configuration of the tip 32.

[0042] The example illustrated in the figure shows a chisel 22 with one of two drill bits 34 constituting a single pair of drill bits 34. In this case, the drill bits 34 are positioned on opposite sides of the tip 32 and may or may not lie in a common plane. As shown in the end view of Figure 5, the drill bits 34 may be slightly offset (in terms of a direct radial alignment). The drill bits 34 form a sharp angle upward and outward (radially) from the tip 32. The sharp angle of the drill bits 34 can be varied to optimize the performance of the application. The term "sharp angle" is taken from the angle between drill bits 34 known in the general industrial machining field. The sharp angle can be between approximately 60° (very sharp) and 180° (very blunt). That is, at least two drill bits form an angle relative to each other in an arc passing through the longitudinal axis, where the measurement of this arc is the sharp angle. Or in another example, an imaginary right cone aligned with the longitudinal axis and having an interior angle measurement equal to the sharp angle will simultaneously contact the full length of all drill bits, of course allowing normal manufacturing tolerances. In the example shown in the figure, the drill angle measured between the two opposing drill bits 34 is approximately 120°.

[0043] In embodiments where the bone chisel has two or more drill bits 34, all drill bits 34 are more likely to share the same apex. Using the previously mentioned example of a hypothetical cone, all drill bits would be placed simultaneously along the side of the cone, allowing for normal manufacturing tolerances. However, upon careful consideration of embodiments where the bone chisel has four drill bits, if necessary, two opposing drill bits could have a different apex than one of the other two opposing drill bits to achieve certain desired cutting or grinding properties. For reasons that will be obvious, it is also feasible, but not superior, for the bone chisel 22 to have an odd number of drill bits (e.g., 3, 5, etc.) to have an even number of drill bits (e.g., 2, 4, 6, etc.). And thus, a bone chisel 22 configured with four drill bits 34 will have four pairs of adjacent drill bits 34 circumferentially arranged around the longitudinal axis – one pair in each quadrant. A bone chisel 22 configured with six drill bits 34 will have six pairs of adjacent drill bits 34, and so on.

[0044] In addition to having at least two drill bits 34, the tip 32 is designed to have a fragment control surface between adjacent pairs of drill bits 34 that will facilitate the intentional movement and / or aggregation of bone fragments. In the dual-drill-bit embodiment shown in the accompanying drawings, adjacent pairs of drill bits 34 are approximately spaced 180 degrees apart. Therefore, this embodiment can be configured with two fragment control surfaces, each extending on both sides of the entire or at least a majority distance between the drill bits 34, thus each spanning an arc of approximately or nearly 180 degrees.

[0045] In some anticipated embodiments of the bone chisel configuration having two or more drill bits, the fragmentation control surfaces will extend between at least one pair of adjacent drill bits, or more preferably between each pair of adjacent drill bits. For example, in an embodiment of the bone chisel 22 configuration having four drill bits, it is anticipated that these drill bits are set to be spaced approximately 90 degrees apart from each other. There will be at least one, but typically four, fragmentation control surfaces, wherein each fragmentation control surface spans an arc of approximately or close to 90 degrees between adjacent pairs of drill bits 34.

[0046] The fragmentation control surface can be formed in various ways. In some anticipated embodiments, the fragmentation control surface may be a flat or curved ramp-like feature extending between one or more drill bits 34. However, in the provided example, the fragmentation control surface includes a multifaceted structure having a first ventral rear wing 36 tilted at a first angle from each of the drill bits 34. The first ventral rear wing 36 is shown as generally planar, however, a non-planar shape is of course feasible. For clarity, whether there is a discrete first ventral rear wing 36 behind the drill bit 36 ​​is a design choice. The first angle can be varied to optimize the performance of the application. In practice, the first angle can be between about 30° and about 60°, and this angle is measured by rotating a 2D image so that the first ventral rear wing 36 appears as a line (i.e., completely perpendicular to the plane of the paper or screen in which it appears). In this orientation, the first angle is measured directly from the longitudinal axis of the chisel 22.

[0047] In most cases, the first ventral flank 36 is positioned relative to its respective drill bit 34 such that when the bone chisel 22 rotates in use, the first ventral flank 36 guides or follows its respective drill bit 34. As previously mentioned, the tip 32 can be formed in various ways, and the cutting / non-cutting direction of the bone chisel 22 is defined by the groove and the working edge (described below). In the example illustrated in the figures, it is said that when the bone chisel 22 rotates in a non-cutting direction for densification mode, the first tail tooth surface 36 guides its respective drill bit 34; and conversely, when the first ventral flank 36 follows its respective drill bit 34, it is said that the bone chisel rotates in a cutting direction, wherein the drill bit 34 cuts or slices bone as it descends. In the densification direction, the first ventral flank 36 effectively forms a large negative angle for the drill bit 34 to minimize fragmentation and shear deformation in the bone (or other body material) at the point of contact with the drill bit 34.

[0048] However, the foregoing statements are generalized and not necessarily applicable to all embodiments. Upon careful consideration, in some applications, it may be desirable to reconfigure the tip such that when the chisel 22 is rotated in a non-cutting direction for densification mode, the first tail tooth surface 36 follows its respective drill bit 34. Indeed, many variations are feasible and within the scope of this invention.

[0049] To reiterate, the debris control surface of the tip 32 can be designed in various ways. In the provided example, the debris control surface includes a second ventral wing 38 formed adjacent to each of the first ventral wing 36 and positioned at a second angle away from each of the first ventral wing 36. The second ventral wing 38 is shown as generally planar, however, a non-planar shape is also possible. For clarity, whether the second ventral wing 38 exists behind the first ventral wing 36 is a design choice. The second angle will be smaller than the first angle and optimized for the application. In practice, the second angle is typically less than about 55°. In an example where the first ventral wing 36 is formed at 45° (relative to the axis), the second ventral wing 38 may be 40° or less. The measurement of the second angle will be performed in a manner similar to that described for the first angle.

[0050] The fragmentation control surface of the tip 32 may also be formed with a relief recess 40 adjacent to each of the second ventral flanks 38. For clarity, the presence or absence of a relief recess 40 is a design choice; the bone chisel 22 can operate satisfactorily without a relief recess 40. Or in other words, in some embodiments, a relief recess 40 may be integrated with the second ventral flanks 38 to make it difficult to distinguish from each other. Specifically, embodiments of the bone chisel configured with more than two drill bits may not be able to include a relief recess 40 due to space constraints. Each relief recess 40 is inclined at a third angle away from its associated second ventral flank 38. The third angle is smaller than the second angle, as determined by a measurement technique similar to that described for the first angle. In instances where the second ventral flanks 38 are formed at 40° (relative to the axis), the relief recess 40 (i.e., the third angle) may be 30° or smaller. Each recessed cavity 40 is placed in a portion of the top 32 between a second lateral flank 38 and a drill bit 34.

[0051] Another element of the fragmentation control surface is a drill cutting face 42 extending between the relief cavity 40 and the adjacent drill bit 34. The drill cutting face 42 may be generally axially positioned or have some other configuration. When the bone chisel 22 rotates in the cutting direction, a large amount of bone fragments accumulate in the area of ​​the relief cavity 40. When the bone chisel 22 rotates in the densification direction, little or no bone fragments accumulate in the area of ​​the relief cavity 40.

[0052] A plurality of grooves or slots 44 are arranged around the body 26. The slots 44 may or may not have a common axial length and radial depth. That is, in some configurations, the slots 44 may not be identical. The slots 44 are preferably, but not necessarily, uniformly circumferentially arranged around the body 26. The diameter of the body 26 can affect the number of slots 44. For example, a body 42 in the range of about 1 mm to about 3 mm may have three or four slots; a body 42 in the range of about 3 mm to about 4 mm may have five or six slots; a body 42 in the range of about 4 mm to about 5 mm may have seven or eight slots; and a body 42 in the range of about 5 mm to about 6 mm may have nine or ten slots. And if desired, even larger drill diameters (e.g., 6 mm to 7 mm) may have even more slots. Of course, for optimal performance and / or better adaptation to the application, the number of slots 44 may differ more or less from the examples given herein.

[0053] In the embodiment illustrated in the figures, the groove 44 forms a helical twist. If the cutting direction is in the right-hand (clockwise) direction, the helix is ​​preferably also in the right-hand direction. This RHS-RHC configuration is shown in all figures, although it should be understood that, if necessary, the cutting direction and the helix direction can be reversed (i.e., to the LHS-LHC direction) to obtain substantially the same result. An LHS-RHC or RHS-LHC configuration can also be used to configure the bone chisel. That is, it is desirable to configure the helix such that the bone chisel 22 is pulled into the hole rather than pushed out of the hole in a densifying operation mode.

[0054] Each groove 44 has a reinforcing surface 46 and a pair of opposing cutting surfaces 48. A ribbed blade back 50 is formed alternately between adjacent grooves 44. Thus, a four-groove bone chisel 22 will have four blade backs 50, a ten-groove bone chisel 22 will have ten staggered blade backs 50, and so on. Each blade back 50 extends between the reinforcing surface 46 of a groove 44 on one side and the cutting surface 48 of a groove 44 on the other side (circumferential). The sharp interface between each blade back 50 and its associated cutting surface 48 is referred to as a working edge 52. Depending on the direction of rotation of the bone chisel 22, the working edge 52 is used to cut or compress bone. That is, when the bone chisel rotates in the cutting direction, the working edge 52 cuts and excavates bone (or other body material). Generally, in the cutting direction, the working edge 52 will slightly tend to pull the bone chisel 22 deeper into the osteotomy 20. As the bone chisel rotates in the densifying (non-cutting) direction, the working edge 52 compresses and radially moves the bone (or other body material) with minimal cutting. This compression and radial displacement manifests as a gentle, laterally outward pushing of the bone structure within a compression mechanism. Typically, in the non-cutting direction, the working edge 52 will have a slight tendency to resist penetration of the bone chisel 22 into one of the osteotomies 20.

[0055] Most of the working edges 52 shown in the illustrations are essentially unbounded because the entire portion of each cutting edge back 50 is cut off behind the working edge 52 to provide full clearance. Unbounded working edges 52 are preferred; however, in some cases, the cutting edge backs 50 can be designed to operate as boundaries. The alternative embodiment in Figure 12 shows a cutting edge back 50 that also acts as a boundary of the working edge 52. In standard prior art augers, boundaries are typically incorporated behind the working edge to help guide the drill in the hole and maintain the drill diameter. In an unbounded design, depending on the application and potentially the diameter of the body 26, the primary taper clearance angle (i.e., the angle between the tangent of the working edge 52 and each cutting edge back 50) can fall between about 1° and about 35° (or greater). It has been found that for a body 26 with a diameter between about 1 mm and about 7 mm, a primary taper clearance between about 5° and about 20° is effective. Of course, the primary tapered clearance angle can vary more or less than the example given here to optimize performance and / or better suit the application. In the case where the blade back 50 forms a boundary behind the working edge 52, as shown in Figure 12, the primary tapered clearance angle is actually 0°.

[0056] As mentioned above, along with the angle of helical twist, for standard RHS-RHC and LHS-LHC configurations, when the diameter of the conical tapered profile of the body 26 decreases, the working edge 52 can be seen to rotate away from the densification direction. In other words, when the densification direction is counterclockwise, when viewed from the top of the body 26 towards its top 32, the helical twist of the working edge 52 is in a counterclockwise direction. Or conversely, when viewed from the top 32 towards the top of the body 26, the twist will be in a clockwise direction. Therefore, when the densification direction is counterclockwise, as all the blade backs 50 and grooves 44 rotate counterclockwise around the longitudinal axis, the working edge 52 will rotate away from the densification direction as each blade back 50 and groove 44 moves downward toward the top 32.

[0057] When rotated in the cutting direction, the cutting surface 48 establishes an angle for each individual working edge 52. An angle is a tilt angle measured from the guide surface of the working edge 52 to an imaginary line extending perpendicular to the surface of the workpiece (e.g., the bone surface within an osteotomy). The angle is a parameter used in various cutting and machining processes to describe the angle of the cutting surface relative to the workpiece. The angle can be positive, negative, or zero. When the bone chisel 22 rotates in the cutting direction, angles from approximately zero degrees (0°) and above will establish a curled cutting edge 52 that is very suitable for cutting / slicing bone. However, it has been found that the cutting functionality of the rotating bone chisel 22 can be improved by changing the angle of the cutting surface 48 to below zero degrees (0°). Specifically, angles of the cutting surface 48 between approximately 0° and approximately -65° (i.e., negative angles) are useful in certain applications.

[0058] As the osteotomy 22 rotates in densification mode, a heel angle is established between the working edge 52 and the blade back 50. As previously described, this angle can be a large negative inclination angle of about 55° to about 90°, which is the supplementary angle to the primary tapered gap angle. From a defining angle, the heel angle is an inclination angle of the working edge 52 as it rotates in a densification direction. However, to avoid confusion with the inclination angle relative to the cutting surface 48, the term heel angle is used. A large negative (or zero) heel angle applies outward pressure at the point of contact between the osteotomy wall 20 and the working edge 52 to create a compression wave before the point of contact, roughly analogous to spreading butter on toast. Bone density enhancement can also be roughly compared to the well-known metal polishing process used to improve the surface quality of metals.

[0059] As the osteotomy 20 is extended, downward pressure needs to be applied by the surgeon to maintain contact between the working edge 52 and the bone surface of the osteotomy 20. That is, when the contact stress exceeds the yield strength of the body material, pressure is required to generate and propagate compression waves in the bone. The complementary conical effect of the osteotomy 20 and the body 26 helps to generate lateral pressure (i.e., in the direction of outward extension). The more force the surgeon applies to pushing the rotating chisel 22 into the osteotomy 20, the greater the lateral pressure. This allows the surgeon to have complete control over the rate of expansion, largely independent of the rotational speed of the chisel 22, which is a potential factor in mastering the short learning curve required for bone density enhancement techniques. Therefore, the strength of the compressive effect depends primarily on the amount of force applied to the chisel 22, controlled by the surgeon. The greater the applied force, the faster the expansion.

[0060] As the working edges 52 are dragged across the bone, the applied force can be decomposed into two components: one perpendicular to the bone surface, pressing the bone outward, and the other tangential, dragging the bone along the inner surface of the osteotomy 20. As the tangential component increases, the working edges 52 will begin to slide along the bone. Simultaneously, the normal force deforms the bone material. If the normal force is low, the working edges 52 will rub against the bone but will not permanently alter its surface. The frictional action will generate friction and heat, but this can be controlled by the surgeon by adjusting the rotation speed and / or pressure and / or irrigation flow rate in real time. Because the body 26 of the osteotomy 22 is conical, the surgeon can lift the working edges 52 at any point during the surgical procedure to allow cooling, preventing them from contacting the bone surface. This can be achieved in a controlled "bouncing" manner, where pressure is applied in short pulses while the surgeon continuously monitors progress and makes fine corrections and adjustments. As the downward force applied by the surgeon increases, eventually the stress in the bone surface exceeds its yield strength. When this occurs, the working edge 52 will plow across the surface and create a groove behind it. The plowing action of the working edge 52 thus gradually expands the osteotomy until the rotating bone chisel 22 reaches the desired depth, at which point, if necessary, a different, larger rotating bone chisel 22 must be used to achieve further expansion.

[0061] The elastic properties of bone are well-documented. If the load applied by a surgeon does not exceed the bone's elastic deformation capacity, the bone quickly returns to its initial (undeformed) state once the stress is removed. On the other hand, if the load applied by a surgeon exceeds the bone's elastic deformation capacity, the bone will deform and permanently change its shape through plastic deformation. In bone, permanent shape changes can be associated with microcracks that allow energy release, a natural defense against complete fracture. If these microcracks are small, the bone remains intact as the osteotomy progresses. When bone is subjected to stress in the region between its yield point and ultimate tensile strength, the material undergoes strain hardening. Strain hardening (also known as work hardening or cold working) is the strengthening of a ductile material through plastic deformation. This strengthening is due to dislocation movement and dislocation formation within the material's crystal structure – in bone, this corresponds to the dislocations formed by the cross-linking between collagen fibers in the bone tissue. When a material is subjected to stress in the region between its ultimate tensile strength and fracture point, the material tends to undergo necking.

[0062] The direction of the helical twist can be designed to facilitate surgeon control, allowing for the application of optimally positioned stress (in the strain-hardening zone) to the bone throughout the extension procedure. Specifically, when the bone chisel 22 is continuously rotated at high speed in a densifying direction and simultaneously forced forward (manually by the surgeon) into the osteotomy 20, the aforementioned RHS-RHC configuration (or alternatively, an LHS-LHC configuration, not shown) of a right-handed cutting direction is applied to the main bone, causing a beneficial reverse axial reaction force. In other words, if the surgeon operating the bone chisel 22 pushes it downward into the osteotomy 20, the reverse axial reaction force acts in the opposite direction to push the bone chisel upward. The reverse axial reaction force is the vertical (or more precisely, the "axial" component relative to the longitudinal axis) of the reaction force (R) applied by the bone to the entire length of the working edge 52 of the bone chisel 22. When the chisel 22 rotates in a densifying direction, the effective large negative inclination angle at the drill bit 34 also generates a reverse axial reaction force. Those skilled in the art will understand that the reverse axial reaction force is generated by the configuration of the drill bit 34 alone or the working edge 52 alone, rather than by the combined action of both as in the preferred embodiment.

[0063] For a surgeon, as the chisel 22 spins in the densification direction, in order to advance the tip 32 toward the bottom of the osteotomy 20, in addition to providing the force required for the plastic displacement / expansion of bone as described above, he or she must also push and overcome the reverse axial reaction force. The chisel 22 is designed so that the surgeon must constantly work, arguably overcoming the reverse axial reaction force, to expand the osteotomy 20 by compression (i.e., when in densification mode). The reverse axial reaction force is not harmful to the surgeon, but rather beneficial, as it allows the surgeon to better control the expansion procedure. Due to the axial reaction force of the drill tip, the chisel 22 will not be pulled deeper into the osteotomy 20 as a standard "upward-cutting" auger or drill tip is designed to generate a traction force that tends to push the chisel into the bone site. A so-called "upward-cutting" drill tip may grab the drill tip and pull it deeper into the osteotomy, which can lead to unintentional over-penetration.

[0064] In the densification mode, the intensity of the reverse axial reaction force is always proportional to the intensity of the force applied by the surgeon in advancing the body 26 to the osteotomy 20. Therefore, this reaction force generation provides the surgeon with immediate tactile feedback, intuitively and naturally informing them whether more or less force is needed at any given moment. This tactile feedback fully utilizes the surgeon's fine tactile sense through the direct application of the reaction force via the osteotome 22. In this densification mode, the mechanical stimulation of the reverse axial reaction force helps the surgeon better control the expansion procedure based on the immediate response of the bone (or other body material) to the expansion process.

[0065] Therefore, the controlled "bouncing" or "pumping" motion becomes more effective and substantially more controllable through the reverse axial reaction force, allowing surgeons to instinctively monitor progress and make immediate, precise corrections and adjustments to the applied pressure without losing control of the rate of expansion. Tactile feedback from the reverse axial reaction force allows a surgeon to visually apply stress to the bone material so that its strain response is better contained within the strain-hardened zone. In any case, the surgeon will strive to maintain the stress (e.g., generated by the force applied by him or her through the rotating bone chisel 22) above the elastic limit and below the fracture point. Of course, bone will remain permanently undeformed until the applied stress exceeds its elastic limit; and applying stress beyond the fracture point will cause the bone (or other bulk material) to fracture – potentially catastrophically.

[0066] The design of the rotating bone chisel 22 allows for simultaneous autografting and bone compaction. Compaction can be defined as a gentle, laterally outward pushing of the bone structure to compact the cells surrounding the entire area of ​​the osteotomy 20. Autografting results from a certain amount of grinding / grinding of bone due to the forced advancement of the top tooth of the chisel 22 into a smaller osteotomy 20. Friction causes bone to be ground away at the points where the outermost edges of the rotating and forced-advancement drill bits 34 contact the bone. Bone fragments primarily accumulate on the second ventroposterior wing 38, immediately following the respective first ventroposterior wing 36. The autografting phenomenon complements the aforementioned basic bone compaction and coagulation effects to further densify the inner wall of the osteotomy. Furthermore, autografting—the procedure of returning the patient's own bone material—enhances the body's natural healing properties to accelerate recovery and improve osseointegration.

[0067] In summary, bone mineral density enhancement is a method of protecting bone and its collagen content to enhance its plasticity. Bone mineral density enhancement allows for the expansion of an osteotomy 20 by using a high-speed rotating osteotomy 20 for clamping (and / or by cutting when the rotation is reversed), under a continuous supply of irrigation fluid, in preparation for subsequent placement of implants or anchoring clips.

[0068] At least one valley 54 is formed at the tip 32 of the chisel 22. The valley 54 is a groove-like structure or cutout in the tooth crest of the central portion of the drill bit 34 passing between adjacent pairs of drill bits 34. Preferably, the valley 54 bisects or substantially bisects the opposing angle between adjacent pairs of drill bits 34. Thus, in an embodiment where the chisel 22 has only two drill bits 34, as illustrated in the figure, a single valley 54 may extend substantially perpendicular to the drill bit 34. In other words, in the double-drill-bit embodiment shown in the accompanying figure, the drill bits 34 are spaced approximately 180 degrees apart, and when bisected by the valley 54, an approximately right angle is created between the valley 54 and each drill bit 34. However, with careful consideration, the valley 54 may unequally bisect the opposing angle between adjacent pairs of drill bits 34, resulting in an acute angle on one side and an obtuse angle on the other side.

[0069] In an exemplary embodiment of a bone chisel configuration with four drill bits, the drill bits can be arranged to be approximately 90 degrees apart from each other, in which case the drill bits 34 are considered to be circumferentially spaced equidistant from each other. The bisecting angle between two adjacent drill bits set at 90 degrees apart creates an angle of approximately 45 degrees between the valley (or valleys) and each drill bit. Although preferably, the valley 54 bisects or substantially bisects the opposing angle between adjacent pairs of drill bits 34, this is not an absolute requirement, as long as the valley 54 passes between adjacent pairs of drill bits 34. Furthermore, in a contemplated four-drill-bite embodiment, the tip of the bone chisel may form two valleys that intersect each other along the longitudinal axis. In this example, each drill bit will be circumferentially offset by approximately 45 degrees from one of the valleys. However, a four-drill-bite embodiment with only one valley bisecting two of the four adjacent drill bits is also possible. This can be an attractive option when the four drill bits are not circumferentially spaced from each other.

[0070] As previously mentioned, a bone chisel 22 with an even number of drill bits (e.g., 2, 4, 6, etc.) is superior to a bone chisel 22 with an odd number of drill bits (e.g., 3, 5, etc.). It should be understood that when a bone chisel has an odd number of drill bits, using a valley 54 to bisect adjacent drill bits 34 becomes problematic, necessitating displacement of the valley relative to the longitudinal axis or other remedies. This is not the case for a bone chisel 22 with an even number of drill bits 34, and for this reason, it is preferable for the bone chisel 22 to have two, four, etc., drill bits 34 so that the valley 54 can pass through the longitudinal axis without interfering with any other drill bits 34. Therefore, although a bone chisel 22 with an odd number of drill bits 34 is certainly feasible and falls within the scope of the appended patent application, a bone chisel 22 with an even number of drill bits 34 has a perceived advantage over a bone chisel 22 with an odd number of drill bits 34.

[0071] Valley 54 has an inclined sidewall 56 that cuts off or removes the central portion of each drill bit 34. That is, the drill bit 34 is cut inward from the sidewall 56 by valley 54. A base plate 58 may be contained between the sidewalls 56. The base plate 58 may be generally flat or slightly curved, while the sidewalls 56 may have a moderate to steep profile. In the side view of FIG4, in one embodiment, the base plate 58 is shown to be generally perpendicular to the longitudinal axis of rotation, while the sidewalls 56 are almost perpendicular to it.

[0072] Valley 54 is one element, or at least a partner, of the debris control surface of tip 32. In most cases, valley 54 does not intersect with slot 44. Therefore, in the example illustrated, the axial depth of valley 54 does not extend beyond the debris control surface (36 to 42) of tip 32. Or in other words, valley base plate 58 is spaced (axially) from the plurality of slots 44. However, it is within the capabilities of those skilled in the art to devise a valley 54 that extends beyond the axial depth of tip 32 and thus into the area of ​​body 26 where slot 44 resides.

[0073] Figures 10A and 10B provide a sequential illustration of one osteotomy enlargement procedure using a rotating bone chisel 22. Figure 10A shows the rotating bone chisel 22 entering the osteotomy 20 as it descends toward its base 62. With careful consideration, the bone chisel 22 may be driven by a surgical engine in a non-cutting (i.e., densifying) or cutting direction, depending on the bone condition assessed by the attending surgeon, similar to the description in Figure 1. The rotational speed of the bone chisel 22 will be greater than 200 rpm, typically between approximately 800 rpm and approximately 1500 rpm. Figure 10B shows the rotating bone chisel 22 reaching the full depth of the osteotomy 20, thus expanding the hole according to the geometry of the bone chisel 22.

[0074] Figure 11A is an enlarged view of one of the areas circumscribed at 11A in Figure 10B. The accumulation of bone fragments and bone debris 62 is shown anterior to the second ventral posterior wing 38, migrating into the groove 44, where bone particles 62 are transferred (i.e., autografted) to the lateral wall of the osteotomy 20. It should be noted that both Figures 11A and 11B depict close-up views of the tip 32 rotating in a non-cutting direction, where the accumulation of bone debris 62 on the second ventral posterior wing 38 can be seen. In contrast, rotation in a cutting direction typically results in the accumulation of bone debris 62 on the drill bit face 42 and within the cutting recess 40.

[0075] Figure 11B illustrates the subsequent removal of the bone chisel 22 from the osteotomy 20. This view shows that a button-like structure 62A of the bone fragment 62 remains at the center of the osteotomy base 62. The residual button-like structure 62A is in the form of a small ridge or protrusion of the drilled fragment 62 that provides a bone growth promoter to encourage inward bone growth and osseointegration with a subsequently installed anchor. In some applications, the residual button-like structure 62A has been found to be particularly beneficial. One such example is a sinus lift procedure, where the fully formed osteotomy 20 is typically filled with an allograft before the anchor is inserted. In such cases, the residual button-like structure 62A acts as an active bone growth promoter that effectively aids in the inoculation of the allograft material. Furthermore, when the implant is screwed into place, a small amount of bone fragment 62 will be pressed down by the implant, like a button. If the implant has a domed or flattened tip, the button-like structure 62A will be pressed down locally by the implant, thus facilitating further gentle stretching of the sinus membrane. Imagine a novel anchor with a valley-like feature at its front end. The residual buckle-like body 62A of the bone fragment 62 would be nested within this complementary valley in the anchor to create a stability-enhancing feature. That is, when paired with a complementary-configuration anchor, the residual buckle-like body 62A of the bone fragment 62 could, over time, provide an additional self-locking point or short bone tenon filling one of the tenon-like valleys in the anchor to further resist lateral displacement under load.

[0076] Figure 12 is an end view of a rotating bone chisel 22 according to an alternative embodiment, wherein the blade back 50 is configured to define the boundary of the working edge 52. Figure 12 depicts an exemplary migration pattern of bone fragments entering the longitudinal groove 44. Although it is an alternative embodiment, the generation and subsequent distribution of bone fragments at the tip 32 will be consistent with the previously described embodiment. In Figure 12, a beneficial effect of the valley 54 on the flow of bone particles 62 from the surfaces 38, 40 of the tip 32 into the groove 44 can be observed. Specifically, the fragments 62 are more evenly distributed in the groove 44, resulting in a smoother operation of the bone chisel 22 with less rotational imbalance. This is particularly beneficial in both cutting and densification modes, where the additional cutting edge of the rotating bone chisel 22 generates bone fragments faster than previously designed. The accumulated bone fragments 62 pushed into the groove 44 are carried away from the tip 32, thereby reducing the likelihood of thermally induced and / or pressure-induced damage to the bone particles 62.

[0077] Figures 5 and 12 are also useful for identifying the enhanced distribution of cutting / grinding edges located at the tip 32. The notched valley 54 forms several novel cutting / grinding edges at its intersection with the fragmentation control surface. Specifically, in addition to the primary cutting / grinding edges formed by the drill bit 34, the bone chisel 22 also includes secondary cutting / grinding edges 64 along the interfaces of the valley 54 and surfaces 36, 38, 40 and / or 42. Thus, by aligning the valley 54 to bisecte adjacent drill bits 34, the number of cutting / grinding edges in the tip 32 of a double-drill bone chisel 22 increases to six compared to a typical prior art design with only two drill bits. Embodiments of the bone chisel 22 with more than two drill bits 34 will experience a proportional increase in the number of cutting / grinding edges in the tip 32. For example, compared to a typical prior art design with only four valleys, a four-drill bone chisel with one of two valleys 54 intersecting in the longitudinal axis is expected to increase to twelve.

[0078] Therefore, the combination of the drill bit 34 and the secondary cutting / grinding edge 64 allows the rotating bone chisel 22 to cut more forcefully when rotating in the cutting direction and grind more forcefully when rotating in the compression direction. As mentioned, one objective of the rotating bone chisel 22 is to avoid removing any bone fragments 62 from the patient. However, the procedure of preparing for osteotomy 20 inevitably produces some bone fragments 62. One advantage of having a secondary cutting / grinding edge 64 is that the unavoidable production of bone fragments 62 is easier for the surgeon and less traumatic for the patient. Reducing trauma is also beneficial to the health of the bone fragments 62 and thereby promotes the efficacy of autologous transplantation.

[0079] Bone fragments 62 distributed in groove 44 advance towards the blade back 50, where, like a centrifuge, they are scraped and pressed into the sidewall of osteotomy 20 and almost immediately transplanted back into the patient's body after dislocation. Bone fragments 62 brought to the bottom 62 of osteotomy 20 are scraped and pressed into the bottom of osteotomy 20. After producing less invasive bone fragments 62, their regenerative health is optimized. Therefore, an autologous graft zone is formed around and below osteotomy 20, promoting regrowth and long-term implant stability.

[0080] Other shapes of the valley 54 are conceivable, including: a U-shaped cross groove in which the bottom 58 is semi-circular; a V-shaped cross groove in which the bottom plate 58 is only a slit where the sidewalls 56 intersect; and a bowl-shaped profile that is less like a valley and more like a pit, as well as other configurations. Another alternative valley configuration is depicted in Figures 13 and 14, in which the sidewalls 56 extend outward or slope from the bottom plate 58. In this example, the included angle between the sidewalls 56 is approximately 120 degrees (i.e., 60 degrees on each side of the longitudinal axis). In this configuration, the drill bit 34 and the first ventral rear wing 36 are significantly shortened, which can be disadvantageous in certain applications and conditions. However, in embodiments where the sidewalls 56 slope outward (similar to having a draft angle), the residual snap-like body (62A in Figure 11B) will be more easily released from the valley 54. In fact, angles ranging from very small (e.g., 5 degrees) to very wide (e.g., close to 180 degrees) are feasible.

[0081] Figures 15 and 16 depict another alternative valley configuration, in which the sidewalls 56 also slope outward from the base plate 58. In this example, the included angle between the sidewalls 56 is approximately 90 degrees (i.e., 45 degrees on each side of the longitudinal axis). Again, the included angle between the sidewalls 56 can be in the range of 0 degrees to slightly less than 180 degrees. In this configuration, the angles where the drill bit 34 and the first ventral posterior wing 36 meet the sidewalls 56 are intentionally rounded or chamfered. Rounding can be an advantage in certain applications and conditions where it is necessary to avoid sharp guide angles. For example, the embodiments of Figures 15 and 16 are good candidates for sinus lift procedures. As in all examples where there is a quasi-draft angle between the sidewalls 56, the remaining button-like body (62A in Figure 11B) will easily eject from the valley 54 after the bone chisel 22 is removed.

[0082] The invention has been described in accordance with relevant legal standards; therefore, this description is illustrative rather than restrictive in nature. Variations and modifications to the disclosed embodiments will be obvious to those skilled in the art and fall within the scope of this invention.

[0083] 20: Osteotomy 22: Rotary bone chisel 24: handle 26:Ontology 28: Drilling rig motor interface 30: Conical / Dome-shaped transition 32: Top 34: Drill bit 36: First lateral ventral wing / surface 38: Second lateral ventral wing / surface 40: Let the hollow be carved 42:Drill cutting surface / body 44: Trench / Channel 46: Dense surface 48: Cutting surface 50: Blade's Back 52: Work Edge 54: Valley 56: Sidewall 58: Base Plate 60: The base of osteotomy 62: Bottom / Bone Fragment / Bone Particle 62A: Button 64: Secondary cutting / grinding edge

Claims

1. A rotating bone chisel, adapted for preparing an osteotomy with a bone density enhancement effect, the rotating bone chisel comprising: A shank establishing a longitudinal axis of rotation, the shank having an upper end and a lower end; a body extending axially from the lower end of the shank, the body having a tapered outer profile that decreases from a maximum diameter adjacent to the shank portion to a minimum diameter adjacent to the apex; the body having a plurality of grooves disposed around the body away from the apex of the shank, each groove having a working edge, each groove spiraling around the body, the working edge winding around the body in a direction opposite to a non-cutting direction as the diameter of the tapered outer profile decreases; the apex having at least two drill bits circumferentially arranged around the longitudinal axis in at least one adjacent pair; a fragmentation control surface extending between the adjacent pairs of drill bits; improvements thereof include: The drill bits form an upward and radially pointed angle less than 180 degrees from the apex, and at least one valley passing through the longitudinal axis and bisecting the adjacent drill bits. The valley intersects at least a portion of the fragmentation control surface. The valley establishes a plurality of secondary cutting / grinding edges at the intersection with the fragmentation control surface. The valley includes an upper inclined sidewall that truncates a central portion of one of the drill bits. The valley includes a base plate disposed between the upper inclined sidewalls. The upper inclined sidewalls are angled outward from each other with a draft angle greater than 90 degrees and less than 180 degrees. The draft angle and the pointed angle converge at a respective apex along each drill bit.

2. The rotating bone chisel as requested in item 1, wherein the base plate is axially spaced from the plurality of grooves.

3. The rotating bone chisel as claimed in claim 1, wherein the base plate is generally perpendicular to the longitudinal axis of rotation of the handle.

4. The rotating bone chisel of claim 1, wherein the drill bits are not radially offset from each other, and the fragment control surface includes a first ventral rear wing extending from each of the adjacent drill bits.

5. The rotating bone chisel of claim 4, wherein the fragment control surface includes a second ventral flank extending from the first ventral flank.

6. The rotating bone chisel of claim 5, wherein the fragment control surface has a cutting recess extending from the second lateral ventral flank.

7. The rotating bone chisel of claim 1, wherein the fragment control surface includes a drill face extending from the drill bit.

8. The rotating bone chisel as requested in item 1, wherein each working edge is unbounded.

9. The rotary bone chisel of claim 1, wherein each groove has a cutting surface defining a bevel angle on one side and a reinforcing surface defining a heel angle on the other side, and a cutting edge is formed between each pair of adjacent grooves.

10. A rotating bone chisel, adapted for preparing an osteotomy with a bone density enhancement effect, the rotating bone chisel comprising: A shank establishing a longitudinal axis of rotation, the shank having an upper end and a lower end; a body extending axially from the lower end of the shank, the body having a apex away from the shank, the body having a tapered outer profile that decreases from a maximum diameter adjacent to the shank portion to a minimum diameter adjacent to the apex; a plurality of grooves disposed around the body, each groove having a working edge, each groove spiraling around the body, the working edge winding around the body in a direction opposite to a non-cutting direction as the diameter of the tapered outer profile decreases; the apex having at least two drill bits circumferentially arranged around the longitudinal axis in at least one adjacent pair; a fragmentation control surface extending between the adjacent pairs of drill bits, the fragmentation control surface including at least one ventral rear wing extending from one of the drill bits in the adjacent pair; modifications thereof include: The drill bits form an upward and radial angle less than 180 degrees from the apex, and at least one valley passing through the longitudinal axis and bisecting the adjacent drill bits. The valley has an upper inclined sidewall that cuts off the central portion of one of the adjacent drill bits. The valley establishes a plurality of secondary cutting / grinding edges at the interface of at least one flank. The valley includes an upper inclined sidewall that cuts off the central portion of one of the drill bits. The valley includes a base plate disposed between the upper inclined sidewalls. The upper inclined sidewalls are angled outward from each other with a draft angle greater than 90 degrees and less than 180 degrees. The draft angle and the apex converge at the respective apex along each drill bit.

11. The rotating bone chisel of claim 10, wherein the upper inclined sidewalls are angled outward from each other by a draft angle.

12. The rotating bone chisel of claim 10, wherein the valley includes a base plate disposed between the upper inclined sidewalls, the base plate being axially spaced from the plurality of grooves.

13. The rotating bone chisel of claim 10 further includes a rounded or chamfered corner at the intersection of the valley and the drill bit.

14. The rotating bone chisel of claim 12, wherein the base plate is generally perpendicular to the longitudinal axis of rotation of the handle.

15. The rotating bone chisel of claim 10, wherein the drill bits are not radially offset from each other, and wherein the at least one ventral rear wing of the fragment control surface includes a first ventral rear wing extending from the drill bit.

Images