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Title:
UNIVERSAL KEYLESS GUIDED SURGERY SYSTEM
Document Type and Number:
WIPO Patent Application WO/2018/071863
Kind Code:
A1
Abstract:
A surgical tool assembly for forming holes in bone at precise locations to controlled depths. The hole forming tool has a leading apical tip and a shank. The shank includes an annular groove at a predetermined distance from the apical tip. An adjustable telescopic stop is coupled to the shank. The telescopic stop includes an indexing gauge supporting a tubular key. The key includes an integrated impeller that accentuates irrigation of the treatment site during surgical procedures. The adjustable telescopic stop may be used in combination with a guided surgery jig. The jig includes a guide bushing having a generally semi-cylindrical alignment valley adapted to receive the spinning key of the telescopic stop. The alignment valley includes a full annular internal abutment step adapted to engage the key when the apical tip reaches a predetermined penetration depth in the bone.

Inventors:
HUWAIS SALAH (US)
Application Number:
PCT/US2017/056661
Publication Date:
April 19, 2018
Filing Date:
October 13, 2017
Export Citation:
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Assignee:
HUWAIS IP HOLDING LLC (US)
HUWAIS SALAH (US)
International Classes:
A61C1/00; A61B17/58; A61C3/02; B23B51/00
Foreign References:
US20070099150A12007-05-03
US8876444B12014-11-04
US20070298375A12007-12-27
US20110238071A12011-09-29
US5941706A1999-08-24
US20040092940A12004-05-13
US20110208195A12011-08-25
Attorney, Agent or Firm:
SHACKELFORD, Jon, E (US)
Download PDF:
Claims:
What is claimed is:

1. An adjustable telescopic stop for a bone drilling tool of the type having a body section and a shank joined in end-to-end fashion, said adjustable telescopic stop comprising:

a tubular key adapted to partially surround the body of a bone drilling tool, said key defining a stop ring adapted to limit over-penetration of an apical tip of the body into bone, said key including at least one resilient finger,

an indexing gauge connectable to the drilling tool and moveably supporting said key, said indexing gauge having a plurality of longitudinal stations, each longitudinal station represents a different location of said stop ring and a different penetration depth of the drilling tool in the bone, said finger of said key selectively engageable with each of said longitudinal stations to restrain said stop ring in a set position, and

said indexing gauge including at least one by-pass flat axially intersecting said longitudinal stations, said finger of said key selectively registerable with said flat to enable said finger to slide in-between longitudinal stations when setting the position of said key.

2. The adjustable telescopic stop of Claim 1, wherein said indexing gauge includes a gripping flange.

3. The adjustable telescopic stop of Claim 2, wherein said gripping flange includes at least one discontinuity suitable to enhance tactile grip.

4. The adjustable telescopic stop of Claim 3, wherein said discontinuity is offset from said flat.

5. The adjustable telescopic stop of Claim 1, wherein said indexing gauge has a central bore adapted to mate with the shank of the drilling tool, said indexing gauge further including at least one cantilever locking segment formed by at least one slit, said locking segment including a spur extending inwardly from said central bore and adapted to engage within a groove of the drilling tool shank.

6. The adjustable telescopic stop of Claim 5, wherein said indexing gauge includes a plurality of annular channels each corresponding to a respective one of said longitudinal stations, said finger of said key including an inwardly extending barb, each said channel adapted to selectively receive said inwardly extending barb, adjacent said annular channels being separated by annular ribs, transitional ramps formed between each said annular rib and said flat, said slit in said indexing gauge passing through said transitional ramps.

7. The adjustable telescopic stop of Claim 1, wherein said key includes at least one vane slot configured to permit the pass-through of irrigating fluid.

8. The adjustable telescopic stop of Claim 1, wherein said key includes a plurality vane slots configured to permit the pass-through of irrigating fluid, each pair of adjacent said vane slots being circumferentially separated by a respective longitudinally extending blade, each said blade having a pair of longitudinally extending edges defining a boundary with the adjacent respective said vane slots.

9. The adjustable telescopic stop of Claim 8, wherein said key has an upper end opposite said stop ring, said key having a lower annular cuff in the region between said stop ring and said vane slots and an annular upper cuff in the region between said upper end and said vane slots.

10. The adjustable telescopic stop of Claim 8, wherein said vane slots and said blades each extend in generally straight axial paths parallel to one another.

11. A combined tool and jig assembly for forming a hole of predetermined depth in bone, said assembly comprising:

a hole forming tool having a body and a shank, said body having an apical end, a tubular key adapted to partially surround said body of said hole forming tool, said key defining a stop ring adapted to limit over-penetration of said apical tip of said body into bone, said key including at least one resilient finger,

an indexing gauge connectable to said shank of said hole forming tool, said indexing gauge having a plurality of longitudinal stations, each longitudinal station representing a different location of said stop ring relative to said apical end of said hole forming tool, said finger of said key selectively engageable with each of said longitudinal stations to restrain said stop ring in a set position, said indexing gauge including at least one by-pass flat axially intersecting said longitudinal stations, said finger of said key selectively registerable with said flat to enable said finger to slide in-between longitudinal stations when setting the position of said key, and

a jig configured to be secured relative to a target drilling location, said jig including a guide bushing, said guide bushing having a laterally open alignment valley adapted to receive said key of said telescopic stop, said alignment valley including an internal abutment step, said internal abutment step having a full annular surface adapted to engage said stop ring of said key when said apical tip has reached a predetermined penetration limit in the bone.

12. The assembly of Claim 11, wherein said alignment valley included a scalloped section partially surrounding said abutment step.

13. The assembly of Claim 11, wherein said indexing gauge includes a gripping flange.

14. The assembly of Claim 13, wherein said gripping flange includes at least one discontinuity suitable to enhance tactile grip.

15. The assembly of Claim 14, wherein said discontinuity is offset from said flat.

16. The assembly of Claim 11, wherein said indexing gauge has a central bore adapted to mate with the shank of the drilling tool, said indexing gauge further including at least one cantilever locking segment formed by at least one slit, said locking segment including a spur extending inwardly from said central bore and adapted to engage within a groove of the drilling tool shank.

17. The assembly of Claim 16, wherein said indexing gauge includes a plurality of annular channels each corresponding to a respective one of said longitudinal stations, said finger of said key including an inwardly extending barb, each said channel adapted to selectively receive said inwardly extending barb, adjacent said annular channels being separated by annular ribs, transitional ramps formed between each said annular rib and said flat, said slit in said indexing gauge passing through said transitional ramps.

18. The assembly of Claim 11, wherein said key includes at least one vane slot configured to permit the pass-through of irrigating fluid.

19. The assembly of Claim 11, wherein said key includes a plurality vane slots configured to permit the pass-through of irrigating fluid, each pair of adjacent said vane slots being circumferentially separated by a respective longitudinally extending blade, each said blade having a pair of longitudinally extending edges defining a boundary with the adjacent respective said vane slots.

20. The assembly of Claim 19, wherein said key has an upper end opposite said stop ring, said key having a lower annular cuff in the region between said stop ring and said vane slots and an annular upper cuff in the region between said upper end and said vane slots.

Description:
UNIVERSAL KEYLESS GUIDED SURGERY SYSTEM

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to US Provisional Patent Application No. 62/408,243 filed October 14, 2016, the entire disclosure of which is hereby incorporated by reference and relied upon.

BACKGROUND OF THE INVENTION

[0002] Field of the Invention. The invention relates generally to rotary drilling tools for forming an osteotomy or hole in bone or other material to receive an implant or anchor or other fixation device, and more specifically toward a novel telescopic stop that limits penetration of the drilling tool to a predetermined depth, as well as to a novel guided surgery jig used in combinations therewith.

[0003] Description of Related Art. An implant is a medical device manufactured to replace a missing biological structure, to support a damaged biological structure, or to enhance an existing biological structure. Bone implants may be found throughout the human skeletal system, including dental implants in a jaw bone to replace a lost or damaged tooth, vertebral implants used to secure cages, joint implants to replace damaged joints such as hips and knees, and reinforcement implants installed to repair fractures and remediate other deficiencies, to name but a few. The placement of an implant often requires a preparation into the bone using either hand osteotomes or precision drills with highly regulated speed to prevent burning or pressure necrosis of the bone. After a variable amount of time to allow the bone to grow on to the surface of the implant (or in some cases to grow onto a fixture portion of an implant), sufficient healing will enable a patient to start rehabilitation therapy or return to normal use or perhaps the placement of a restoration or other attachment feature.

[0004] In the example of a dental implant, preparation of a hole or osteotomy is required to receive a bone implant. The depth of an osteotomy is determined by the amount of axial movement that the clinician imparts on a drilling tool as he or she inserts the drilling tool into the bone tissue. If the depth of the bore is too long, it can puncture the sinus cavity in the maxillary, or the mandibular canal (which contains nerves) in the mandible. Likewise, the roots of adjacent teeth also can be adversely affected by an improperly sized osteotomy.

[0005] To ensure that a drilling tool is inserted into the bone to a known depth, the drilling tool may contain markings that signify specific depths. For example, a drilling tool may have bands of etched markings that indicate the bore depth at several locations. The use of these visual markers is, of course, limited to the clinician's ability to see the mark as the drilling tool is being inserted into the patient's mouth. Accordingly, the clinician is required to keep his or her visual attention on the depth marker as he or she slowly proceeds with the axial movement that causes the drilling tool to be inserted deeper and deeper into the bone. Visibility in such cases can be obscured by irrigation fluid and tools and other obstructions, making the traditional visual markers sometimes difficult to use.

[0006] The prior art discloses various types of stop elements that prohibit insertion of a drill into the bone tissue beyond a predetermined depth. The methods employed by these prior are schemes are either difficult/cumbersome to use, or are expensive to produce. A few notable examples are described below.

[0007] U.S. Publication No. 2007/0099150 to Daniele discloses a depth stop key for a dental drill. The shank of the drill has a series of grooves. Pawls at the top of the stop key selectively engage the grooves in the shank to set the drilling depth. Drilling depth is adjusted by moving the stop key up or down along the drill shank.

[0008] German patent document DE3800482 to List teaches a depth stop for a surgical drill. A series of annular ribs are formed along the drill shank. A stop key fitted with a spring and ball locking mechanism sequentially snaps into the annular ribs to set the drilling depth.

[0009] US Patent No. 7,569,058 to Ralph discloses an adjustable depth stop for a surgical device used to form pre-threaded holes in bone. A series of annular ribs are formed along the length of the tap shank. A stop key fitted with flexible pawls sequentially snaps into the annular ribs to set the tap depth. A screw-on locking cap threads over the flexible pawls to secure them in an adjusted position.

[0010] US Patent No. 6,739,872 to Turri discloses an adjustable depth stop for a surgical drill in which a screw thread is formed on or attached to the drill shank. A sleeve-like stop key mates with the screw thread to allow the axial position of the key to be adjusted by turning.

[0011] Common disadvantages perceived among the prior art are many, and include lack of ability to be installed on and removed from any drilling tool. Rather, in each case a specially manufactured drilling tool is required. Another common disadvantage is that multiple grooves and/or screw threads must be formed in the tool shank. For high-speed applications, the multiple grooves risk weakening the shank with multiple stress-concentrating nodes that invite unwanted vibrations in use. The multiple grooves/threads also add to manufacturing expense. And furthermore, each groove/thread in the shank represents a hard-to-clean location for post-operative sterilization prior to re-use. Multiple grooves in the tool shank compound this concern, resulting in increased time and effort required during the customary sterilization and cleaning processes. Still further disadvantages of the prior art depth-stop concepts relate to the overall lack of suitability for retrofit use across a wide range of drilling tools marketed by different manufacturers. And yet further, none of the prior art depth-stop concepts are well-suited for use with the growing demand for guided surgery applications.

[0012] Korean patent document KR20060096849 to Hsieh discloses a guided surgery system in which a mouth jig has a guide feature to provide location and orientation control. Hsieh teaches the diameter of the guide feature can be reduced by adhering an additional magnetic guide bushing. However, the Hsieh system is not coordinated for use with a depth-stop feature, thereby making it difficult or cumbersome to utilize depth control in combination with guided surgery.

[0013] There is therefore a need in the art for an improved stop element that prohibits insertion of a surgical drilling tool or bur into the bone tissue beyond a predetermined depth, and which can be used conveniently in combination with a jig for guided surgery.

BRIEF SUMMARY OF THE INVENTION

[0014] According to a first aspect of the present invention. An adjustable telescopic stop is provided for a bone drilling tool of the type has a body section and a shank joined in end-to-end fashion. The adjustable telescopic stop comprises a tubular key adapted to partially surround the body of a bone drilling tool. The key defines a stop ring that is adapted to limit over-penetration of an apical tip of the drilling tool body into bone. The key includes at least one resilient finger. An indexing gauge is connectable to the drilling tool and moveably supports the key. The indexing gauge has a plurality of longitudinal stations. Each longitudinal station represents a different location of the stop ring and a different penetration depth of the drilling tool in the bone. The finger of the key is selectively engageable with each of longitudinal station to restrain the stop ring in a set position. The indexing gauge includes at least one by-pass flat that axially intersects the longitudinal stations. The finger of the key is selectively registerable with the flat to enable the finger to slide in-between longitudinal stations when setting the position of the key.

[0015] The by-pass flat enables a user to quickly set, and quickly re-set, the adjustable position of the key even while wearing surgical gloves.

[0016] According to a second aspect of the present invention, a combined tool and jig assembly is provided for forming a hole of predetermined depth in bone. The assembly comprises: a hole forming tool that a body and a shank. The body has an apical end. A tubular key is adapted to partially surround the body of the hole forming tool. The key defines a stop ring that is adapted to limit over-penetration of the apical tip of the body into bone. The key includes at least one resilient finger. An indexing gauge is connectable to the shank of the hole forming tool. The indexing gauge has a plurality of longitudinal stations; each longitudinal station represents a different location of the stop ring relative to the apical end of the hole forming tool. The finger of the key is selectively engageable with each longitudinal station to restrain the stop ring in a set position. The indexing gauge includes at least one by-pass flat axially intersecting the longitudinal stations. The finger of the key is selectively registerable with the flat to enable the finger to slide in-between longitudinal stations when setting the position of the key. A jig is configured to be secured relative to a target drilling location. The jig includes a guide bushing. The guide bushing has a laterally open alignment valley adapted to receive the key of the telescopic stop. The alignment valley has a full annular abutment step adapted to engage the stop ring of the key when the apical tip has reached a predetermined penetration limit in the bone

[0017] The alignment valley provides maximum access and visibility into an edentulous jaw site for the surgeon. The laterally open configuration allows substantially increased irrigation capacity to the osteotomy. The full annular abutment step helps maintain dimensional stability of the guide bushing and enables the abutment step to have a relatively thin profile.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0018] 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:

[0019] Figure 1 depicts an exemplary application of the present invention at an edentulous jaw site that needs expansion to receive an implant;

[0020] Figure 2 is a view as in Figure 1, but showing the osteotomy in the process of being prepared with a drilling tool fitted with a telescopic stop according to the present invention;

[0021] Figure 3 is a view as in Figure 2 showing the drilling tool at full depth as limited by the telescopic stop and the concurrent application of irrigating fluid;

[0022] Figure 4 shows the resulting fully prepared osteotomy ready to receive an implant;

[0023] Figure 5 is a view as in Figure 4 in which an installed implant is poised to receive an abutment or base for subsequent prosthetic (not shown);

[0024] Figure 6 is an exploded view of a drilling tool according to one embodiment of the invention, in which an auto-grafting rotary osteotome is fitted with an adjustable telescopic stop; [0025] Figure 7 is a perspective view of a drilling tool with adjustable telescopic stop shown in a lowermost adjusted position or longitudinal station in solid lines, and in an uppermost adjusted position or longitudinal station in phantom;

[0026] Figure 8 is a cross-sectional view taken generally along lines 8-8 in Figure 7;

[0027] Figure 9 is a cross-sectional view as in Figure 8 but depicting the irrigation fluid passing capability provided by vane slots in the telescopic stop;

[0028] Figure 10 is a cross-sectional view taken generally along lines 10-10 in Figure 9;

[0029] Figure 11 is an enlarged cross-section through one of the vane slots as indicated by the area circumscribed at 11 in Figure 10, and showing irrigating fluid being impelled through a vane slot as the telescopic stop and the drilling tool rotate in a clockwise direction;

[0030] Figure 12 is a view as in Figure 11, but showing irrigating fluid being impelled through a vane slot as the telescopic stop and drilling tool rotate in a counter-clockwise direction;

[0031] Figure 13 is a view as in Figure 2 showing an osteotomy in the process of being prepared with an auto-grafting rotary osteotome fitted with a telescopic stop according to the present invention, and wherein a guided surgery jig is used to provide alignment assistance;

[0032] Figure 14 is a view as in Figure 13 showing the rotary osteotome at full depth as limited by the telescopic stop and the concurrent application of irrigating fluid;

[0033] Figure 15 is a cross-sectional view as taken generally along lines 15-15 in Figure 14;

[0034] Figure 16 is a cross-sectional view as in Figure 15, but showing a different drilling depth due to the adjustable key being positioned in a different longitudinal station;

[0035] Figure 17 is a simplified depiction of a human skeleton highlighting some examples of areas in which the present invention might be effectively applied;

[0036] Figure 18 is an enlarged view of a human vertebrae;

[0037] Figure 19 is a view of the vertebrae as in Figure 18 shown in cross-section with a combined rotary osteotome and depth telescopic stop according to one embodiment of this invention disposed to enlarge an osteotomy for the purpose of receiving a fixation screw or other implant device;

[0038] Figure 20 is an exploded view of the telescopic stop according to an alternative embodiment;

[0039] Figure 21 shows the telescopic stop of Figure 20 held in the hands of a surgeon or technician preparing to re-set the depth stop position; [0040] Figure 22 is a view as in Figure 21 but showing the key portion of the telescopic stop rotated a quarter-turn so that its fingers are aligned with a by-pass flat to enable quick re- setting of the depth stop position;

[0041] Figure 23 is a perspective view of a guide bushing according to an alternative embodiment;

[0042] Figure 24 is a front elevation of the telescopic stop of Figure 20 seated in the guide bushing of Figure 23; and

[0043] Figure 25 depicts an osteotomy in the process of being prepared using a hole forming tool fitted with the telescopic stop of Figure 20 and using a guided surgery jig incorporating the guide bushing of Figure 23.

DETAILED DESCRIPTION OF THE INVENTION

[0044] Referring to the figures, wherein like numerals indicate like or corresponding parts throughout the several views, Figures 1-5 show the exemplary periodontal context of an edentulous jaw site 30, in which an osteotomy 32 must be prepared in order to receive an implant 34. In Figure 1, the edentulous jaw site 30 is shown in the pre-operative condition. One method of preparing an osteotomy 32 is to drill a hole using traditional drilling-type dental burs that bore into the host bone material. Another method is described in US 9,028,253 issued May 12, 2015 to Huwais, the entire disclosure of which is hereby incorporated by reference in jurisdictions that recognize incorporation by reference. According to the method of US 9,028,253, a pilot hole is first bored into the recipient bone at the edentulous jaw site 30. The small bored pilot hole is then expanded using a series of progressively larger high-speed rotary osteotomes 36 in a hand-held surgical drill motor 38. The rotary osteotomes 36 are designed to auto-graft the host bone material directly into the sidewalls of the osteotomy 32 while forcibly expanding the osteotomy 32 using modulated pressure combined with copious irrigation 39, resulting in a smooth, highly densified osteotomy 32 capable of providing high initial stability for a subsequently placed implant 34 or other fixture device. However, it will be appreciated that the inventive features of this invention are not exclusively limited to use with the rotary osteotome 36 like that depicted in the drawings. Nevertheless, the present invention is well-adapted for use with the high-speed rotary condensing osteotome 36, and is therefore referenced as a preferred example herein.

[0045] The rotary osteotome 36 is described in US 9,326,778 issued May 3, 2016, and also in WO 2015/138842 published September 17, 2015, both to Huwais, the entire disclosures of which are hereby incorporated by reference in jurisdictions that recognize incorporation by reference. Generally stated, the auto-grafting osteotome 36 includes a shank 40 and a working end or body 42. The shank 40 is basically an elongated cylindrical shaft that establishes a longitudinal axis of rotation A for the rotary osteotome 36 when driven at high speed (e.g., greater than 200 rpm; typically in the range of 800-1500 rpm) by the drill motor 38. A drill motor engaging interface 44 is formed at the distal upper end of the shank 40 for connection to the drill motor 38. Of course, the particular configuration of the interface 44 may vary depending on the type of drill motor 38 used, and in some cases may even be merely a smooth portion of the shank shaft against which the jaws of a collet grip by friction alone. An annular groove 45 is disposed at a predetermined intermediate axial location along the shank 40. The groove 45 is preferably shallow, with relatively square inset corners. The longitudinal length (i.e., width) of the groove 45 may be in the range of about 10% to 100% of the diameter of the shank 40, although widths of greater or lesser dimensions are possible.

[0046] The body 42 of the osteotome 36 joins to the shank 40 at a transition 46, which may be formed with a tapered or domed shape. The angle or pitch of the transition 46 may be described by a transition angle measured relative to the longitudinal axis A. The transition 46 normally helps spread the irrigating fluid something like an umbrella as the surgeon irrigates with water (or saline, etc.) during use. Irrigation of the osteotomy site 32, as depicted at 39 in Figures 2 and 3, is especially important when using an auto-grafting type rotary osteotome 36 to facilitate its hydrodynamic affects and to manage heat.

[0047] The working end or body 42 of the osteotome 36 has conically tapered profile decreasing from a maximum diameter adjacent the shank 40 to a minimum diameter adjacent an apical end 48. The apical end 48 is thus remote from the shank 40, with the aforementioned groove 45 being located along the shank 40 at a predetermined distance from the apical tip 48 for reasons that will be described. The working length or effective length of the body 42 is proportionally related to its taper angle and, in cases where the osteotomy 32 is formed by a sequence of progressively larger osteotomes 36, is also related to the size and number of osteotomes 36 in a surgical kit. Preferably, all osteotomes 36 in a kit will have the same taper angle, and the diameter at the upper end of the body 42 for one osteotome 36 will be approximately equal to the diameter adjacent the apical end of the body 42 for the next larger size osteotome 36.

[0048] The apical end 48 may include one or more lips 50. A plurality of grooves or flutes 52 are disposed about the body 42. The flutes 52 are preferably, but not necessarily, equally circumferentially arranged about the body 42. A rib or land is formed between adjacent flutes 52, in alternating fashion. Thus, a four-flute 52 osteotome 36 will have four interposed lands, a ten- flute 52 osteotome 36 will have ten interleaved lands, and so forth. Each land forms a working edge. Depending on the rotational direction of the osteotome 36, the working edge either functions to cut bone or condense bone. That is, when the osteotome 36 is rotated in the cutting direction, the working edges slice and excavate bone (or other host material when used in non-bone applications). However, when the osteotome 36 is rotated in the condensing (non-cutting) direction and pushed into the osteotomy 32 with modulating pressure, the working edges compress and radially displace bone with little to no cutting. This compression and radial displacement is exhibited as gentle pushing of the osseous structure laterally outwardly in a condensation mechanism.

[0049] To ensure that the apical end 48 of the rotary osteotome 36 (or the tip of a traditional drilling bur or other boring tool) does not exceed a desired depth in the bone, an axial telescopic stop, generally indicated at 54, is provided. The telescopic stop 54 is shown exploded in Figure 6 and assembled together with a rotary osteotome 36 in Figure 7. The telescopic stop 54 comprises a tubular key, generally indicated at 56. The title of the present patent application includes the term "keyless" which is intended to reference the fact that the key is not a loose-piece element but rather is integrated into the assembly. Thus, the key 56 in effect serves the function of prior art loose keys that were required to be manually set-in place and removed several times during the course of a surgical procedure. The integrated key 56 of this present invention is centered about a central axis B that coincides with the longitudinal axis A of the shank 40 when the two are assembled together as a unit. The key 56 is collar-like with a generally constant exterior diameter. An annular stop ring 58 is formed at the lowermost end of the key 56. The stop ring 58 is preferably smooth and lies perpendicular to the central axis B. However, in some contemplated embodiments the surface of the stop ring 58 may be textured or crenelated.

[0050] The key 56 may, optionally, include a plurality of vane slots 60 configured to permit irrigating fluid 39 to readily pass-through to reach the body section 42 of the osteotome 36. The vane slots 60, therefore, allow the irrigating fluid 39 to better wash over the osteotomy site 32, thereby allowing for better heat management at the treatment site. As illustrated by the broken directional arrows in Figure 9, irrigating fluid 39 directed toward the key 56 passes laterally through the slots 60, allowing the fluid 39 to engage the drilling tool 36 and then be pulled by its flutes 52 in a downward spiral (into the osteotomy 32). When an auto-grafting rotary osteotome 36 is used as the hole-forming tool, a copious flow of irrigating fluid 39 through the vane slots 60 allows the osteotome 36 to generate hydrodynamic effects which, as described in the aforementioned WO 2015/138842, substantially enhance the hole formation procedure. [0051] The vane slots 60 may, optionally, be configured as an integral impeller to accelerate the radially inward flow of water. In this configuration, the rotating motion of the key 56 (synchronously locked to the rotating osteotome 36 through friction) is used as an energy source, together with the shape or configuration of the vane slots 60, to facilitate movement of the irrigating fluid inwardly toward the osteotome 36. Each pair of adjacent the vane slots 60 may be seen as being circumferentially separated by a respective longitudinally extending blade 62. The blades 62 terminate at the lower end of the key 56, i.e., near the stop ring 58, at an annular lower cuff 64. Said another way, the lower cuff 64 is the region of the key 56 between the stop ring 58 and the vane slots 60. Similarly, an annular upper cuff 66 is formed by the region of the key 56 between its upper end and the vane slots 60. The blades 62 thus extend between the upper 66 and lower 64 cuffs forming a ventilated cage-like structure.

[0052] In the illustrated embodiment, the vane slots 60 are spaced from one another in equal circumferential increments about the key 56, and the blades 62 are each of generally equal width forming a symmetrical appearance. The vane slots 60 and the interposed blades 62 respectively extend in generally straight axial paths parallel to one another and parallel to the central axis B. However, in a contemplated alternative embodiment, the vane slots 60 and blades 62 may be spiraled or slanted in their arrangement around the key 56 to promote irrigation flow 39 if desired. Indeed, the vane slots 60 need not even be slots per se, but could in fact be designed as holes of round or other geometric shape that permit the pass-through of irrigating fluid (with or without an impeller effect). The number and/or relative sizes of the vane slots 60 may depend on the exterior diameter of the key 56 and the width of the intervening blades 62. In the examples shown in Figures 6, 7 and 10, six vane slots 60 (and six blades 62) are arranged in equal circumferential increments about the key 56. Furthermore, the number or size of vane slots 60 (or blades 62) may be determined considering how much irrigating fluid is required for the body section 42 of the osteotome 36 and/or the degree to which column strength of the key 56 is affected.

[0053] Turning to Figures 11-12, one exemplary embodiment is illustrated as a means by which to accomplish the impeller function via the shape of the blades 62. Each blade 62 can be viewed as having a pair of longitudinally extending edges 68. The edges 68 define the respective boundaries with the adjacent the vane slots 60. At least one of the edges 68 of each blade 62 may be canted or sloped like a chisel to impel irrigating fluid through the adjoining vane slot 60 along a radially inward vector when the telescopic stop 54 is rotated about its central axis B. Preferably, both edges 68 of the blade 62 are canted, in opposing directions, so that irrigating fluid will be propelled inwardly through the vane slots 60 when the telescopic stop 54 is rotated about the central axis B in either rotary direction. Figure 11 shows that irrigating fluid 39 is impelled inwardly toward the body section 42 of the osteotome 36 when the telescopic stop 54 is rotated clockwise. To be specific, the left-side edge 68 is slanted inward so that irrigating fluid 39 that comes in contact with that edge 68 is urged or pumped inwardly. Conversely, Figure 12 shows that irrigating fluid 39 will be propelled inwardly through the vane slot 60 when the telescopic stop 54 is rotated counter-clockwise.

[0054] The telescopic stop 54 may be of a fixed length design, i.e., so that only one predetermined drilling depth is possible, or alternatively may include an indexing gauge, generally indicated at 70, that allows the key 56 to be moved to various pre-selected longitudinal stations relative to the osteotome 36. In this manner, the stop ring 58 can be set or re-set, at the time of use, at different heights relative to the apical end 48 of the osteotome 36, thus achieving different pre-determined drilling depths into the bone. For example, in the illustrated embodiments five longitudinal stations are established corresponding to drilling depth limits of 6, 8, 10, 11.5 and 13mm. That is to say, when the key 56 is moved to the first longitudinal station along the indexing gauge 70, the axial distance between the apical end 48 and the stop ring 58 is 6mm. In Figures 7- 9, the key 56 is shown in solid lines positioned in this first longitudinal station. When the key 56 is moved to the second longitudinal station along the indexing gauge 70, the axial distance between the apical end 48 and the stop ring 58 is 8mm. When the key 56 is moved to the third/middle longitudinal station along the indexing gauge 70, the axial distance between the apical end 48 and the stop ring 58 is 10mm. When the key 56 is moved to the fourth longitudinal station along the indexing gauge 70, the axial distance between the apical end 48 and the stop ring 58 is 11.5mm. And when the key 56 is moved to the fifth/last longitudinal station along the indexing gauge 70, the axial distance between the apical end 48 and the stop ring 58 is 13mm. In Figures 7 and 8, the key 56 is shown in broken or phantom lines positioned in this fifth/last longitudinal station. Of course, the indexing gauge 70 can be configured with more or less longitudinal stations, and the predetermined distances between apical end 48 and stop ring 58 can be designed to suit different needs or applications.

[0055] As shown in the cross-sectional view of Figure 8, the indexing gauge 70 locks onto the shank 40 via its groove 45. In this manner, the indexing gauge 70 is securely positioned between the osteotome 36 and the key 56. (In the aforementioned case where the telescopic stop 54 is of a fixed length design, the key 56 could be configured to directly connect to the groove 45 without an intermediate indexing gauge 70.) In the illustrated examples, the indexing gauge 70 has a generally cylindrical or barrel-like shape centered along the central axis B. A central bore 72 passes through the indexing gauge 70 and is sized to snugly surround the shank 40 with no discernable play between the two. The lower end of the central bore 72 opens into a conically widening throat 74. The funnel-like conical pitch of the throat 74 is formed at a throat angle relative to the central axis B, as shown in Figure 8. In one embodiment, the throat angle may be intentionally designed smaller than the transition angle, which provides some advantages when design-paired with the axial location of the transition 42 on the osteotome 36. For example, the throat 74 of the indexing gauge 70 and the transition 46 of the osteotome 36 may be designed to meet along a circular line of contact, which may improve the locking force and/or rotational stability between the indexing gauge 70 and the osteotome 36, particularly for larger diameter osteotomes 36. The circular line of contact may also help establish a seal between the indexing gauge 70 and the osteotome 36 so that debris will be less inclined to accumulate behind their interface which could potentially build up pressure and urge a disconnection of the indexing gauge 70 from the groove 45.

[0056] The top end of the indexing gauge 70 includes at least one, and preferably a plurality of, cantilever locking segments 76. In the illustrated examples, the indexing gauge 70 is formed with four locking segments 76. The locking segments 76 could be formed by cutting one or more narrow radial slits into the top of the indexing gauge 70. Each locking segment 76 includes a spur 78 that extends inwardly from the central bore 72 and engages within the annular groove 45 of the shank 40, as best seen in Figure 8. In this manner, the indexing gauge 70 self-locks to the shank 40 of the osteotome 36 when the indexing gauge 70 is slid into position and its one or more spurs 78 register with groove 45. The locking segments 76 may each be formed with a chamfered nose to help distribute the flow of irrigating fluid 39 in use.

[0057] The aforementioned longitudinal stations of the key 56 are established by annular channels 80 disposed about the external surface of the indexing gauge 70. Each adjacent pair of the channels 80 is separated by a respective annular rib 82. Depth number indicia may be disposed in or near the channels 80 to indicate a distance between the stop ring 58 and the apical end 48 corresponding to each longitudinal station. For example, using the previous exemplary pre-set drilling depths, the number "6" could be visibly embossed inside the first annular channel 80; the number "8" in the second annular channel 80; the number "10" in the third annular channel 80; the number "11.5" in the fourth annular channel 80; and the number "13" in the fifth/last annular channel 80.

[0058] One or more fingers 84 extend from the upper end of the key 56, each carrying an inwardly extending prong or barb 86 designed to seat within a selected one of the annular channels 80. The annular channels 80 are each the same width which corresponds to the width of the barbs 86, and are therefore adapted to selectively receive the inwardly extending barbs 86 of the key 56 as the key 56 is moved from one longitudinal station to another. (Although, the width of the ribs 82 will vary depending on the predetermined spacing between the longitudinal stations.) The barbs 86 may be chamfered with camming faces to facilitate movement between the annular channels 80 as a user moves the key 56 from one longitudinal station to another in setting and re-setting the depth stop. In this manner, the fingers 84 resiliency flex as the barbs 86 move into and out of registry with the annular channels 80 using moderately applied external force, and yet securely hold the key 56 in each longitudinal station when the external force is removed.

[0059] One particular advantage of the indexing gauge 70 is that it can be installed on and removed from any osteotome 36 or drilling tool having at least one groove 45 in its shank 40 at a longitudinally coordinated location such that relative distance between the stop ring 58 and the apical end 48 will correspond to the intended drilling depth limit. Another advantage is that an adjustable position key 56 can be utilized without forming multiple grooves in the tool shank 40, which would otherwise weaken the shank 40 with multiple stress-concentrating nodes that invite unwanted vibrations in use, and which add to manufacturing expense. And furthermore, multiple grooves in the tool shank 40 could increase the effort required post-operatively during the customary sterilization and cleaning processes.

[0060] The present invention, when configured with an indexing gauge 70, can be better suited to retrofit use across a wide range of drilling tools/burs marketed by different manufacturers. That is to say, in the case where manufacturers of different drilling tools form a groove 45 on their tool shank at different longitudinal positions relative to the apical end, or perhaps form grooves 45 of different shapes/sizes, it is possible to custom-manufacture an indexing gauge 70 for each manufacturer's specifications yet universally use the same keys 56 to fit across the spectrum of those various custom indexing gauges 70. For example, if Company X manufactures drilling tools and has a unique specification for the size and location of grooves 45 it forms on its tool shanks, and if Company Y manufactures drilling tools and has a consistently different specification for the size and location of grooves 45 it forms on its tool shanks, then an indexing gauge 70 specially fitting to Company X products can be offered, along with a different indexing gauge 70 specially fitting to Company Y products. And yet, the same key 56 may be made to fit both types of indexing gauges 70.

[0061] Turning now to Figures 13-16, the osteotome 36 and combined telescopic stop 54 are show for use in an optional guided surgery application. Generally stated, guided surgery utilizes a custom-fabricated jig, generally indicated at 88, to provide pre-determined location and orientation assistance to the surgeon. The jig 88 may take many different forms, and is not intended to be limited to the illustrated examples which depict a fairly simple over-tooth guardlike structure. Indeed, the principles on this invention in the context of guided surgery applications, as described more fully below, can be implemented across many different platforms and types of jigs 88 including those jigs 88 which are larger, provide for many osteotomy 32 locations and/or are more complex in construction.

[0062] The jig 88 is configured to be secured over a target drilling location, which in the exemplary dental context may be an edentulous jaw site 30. The target drilling location will naturally vary for each patient and according to the needed surgical procedure. In order to best cooperate with the telescopic stop 54, the jig 88 includes a novel guide bushing 90 which establishes an alignment valley 92 that is sized and shaped so as to center the longitudinal axis A of the osteotome 36 with the target drilling location when used in combination with the telescopic stop 54. The alignment valley 92 may be formed in various ways. For example, in the illustrated examples the alignment valley 92 is formed in the shape of a semi-cylinder having an internal diameter that is configured slightly larger than the outer diameter of the key 56 to receive the highspeed rotating key 56 with minimal friction and yet without excessive play/clearance. Although not shown in the drawings, it is contemplated that the alignment valley 92 may take other forms including, for example, the shape of a "V" or a squared notch or other open geometry.

[0063] The alignment valley 92 is oriented within the jig 88 to open toward the outer gum of the patient, thus providing maximum access and visibility into the edentulous jaw site 30 for the surgeon. That is to say, the half-cylinder shape of the bushing 90 provides the operator with superior visual and physical access to the edentulous jaw site 30. The alignment valley 92, which is not fully enclosed like in many prior art designs, allows substantially increased irrigation capacity to the osteotomy 36, as illustrated in Figure 14. Another advantage of the open (C-shaped) configuration of the alignment valley 92 is that, when used in conjunction with a rotary expanding osteotome 36, the bone is more freely able to expand laterally. Furthermore, the open-sided bushing 90 allows relatively long-length osteotomes 36 to be navigated laterally into position from a starting point outside the patient's mouth. Thus, for patients with small mouths, or with a condition that might otherwise make wide jaw opening uncomfortable, the semi-cylindrical bushing 90 offers a significant benefit. In one contemplated embodiment (not shown) the alignment valley 92 terminates directly adjacent the patient's skin or bone at the edentulous jaw site 30. In this manner, the aforementioned depth control afforded by the telescopic stop 54 functions precisely in the manner described, with the alignment valley 92 providing a sighting- reference to aid in locating the osteotomy 32 and the telescopic stop 54 providing depth control.

[0064] The alignment valley 92 may, optionally, include an internal ledge or abutment step 94. The abutment step 94 establishes an elevated surface configured to engage the spinning stop ring 58 of the key 56 when the osteotome 36 has reached the desired drilling depth. In the case of a semi-cylindrical bushing 90, the abutment step 94 may be semi-annular, or full-annular as described below in connection with the alternative embodiment of Figures 23-25. One advantage of the abutment step 94 is to provide a perfectly smooth and perpendicular surface against which the rapidly rotating stop ring 58 will contact. Unlike the often imperfect surface of a patient's natural skin or exposed bone, the abutment step 94 is engineered to precision and will afford the surgeon certain and immediate haptic feedback when the desired drilling depth has been achieved. In cases where the key 56 is made from a polymeric material, the smooth surface of the abutment step 94 may help avoid abrasion or distortion, thus extending the operating life of the telescopic stop 54 and perhaps enabling re-use of the telescopic stop 54 in one or more future surgical applications.

[0065] The elevation of the abutment step 94 above the patient's skin or bone at the edentulous jaw site 30 must be factored into the pre-set drilling depths established by the several longitudinal stations of the key 56. For example, if the elevation of the abutment step 94 is 2mm, then using the previous examples the actual drilling depths established by an indexing gauge 70 having five longitudinal stations will be 4, 6, 8, 9.5 and 11mm, respectively. That is to say, the 2mm elevation of the abutment step 94 (used as an example only) will subtract 2mm from each of the otherwise predetermined drilling depths established by the indexing gauge 70 for the longitudinal stations of the key 56. In Figure 15, where the key 56 is shown having been set to the first longitudinal station, the drilling depth will be (for example) 4mm. However, in Figure 16, the key 56 is shown set to the fifth/last longitudinal station and the drilling depth will be (for example) 11mm.

[0066] Of course, it is possible to design the indexing gauge 70 specifically for use with the guided surgical jig 88 so that the customary drilling depths are achieved without subtracting for the elevation of the annular abutment 94. Or alternatively, the depth number indicia may be designed to accommodate use of the telescopic stop 54 with and without a jig 88 having an abutment step 94. For example, using the previous exemplary pre-set drilling depths, the numbers "6(4)" could be visibly embossed inside the first annular channel 80; the numbers "8(6)" in the second annular channel 80; the numbers "10(8)" in the third annular channel 80; the numbers "11.5(9.5)" in the fourth annular channel 80; and the numbers "13(H)" in the fifth/last annular channel 80. Of course, many alternatives are possible to accommodate the loss of drilling depth caused by the annular abutment 94.

[0067] The novel features of this invention are not limited to dental applications, but in fact are directly adaptable to many orthopedic applications as well. Figure 17 depicts a human skeleton, with but a few of the many possible zones of use being highlighted by broken circles. Indeed, the possible orthopedic applications are not limited to these highlighted zones only. Notwithstanding, one area of particular investigation is the spine or lumbar region, as exemplified in Figures 18 and 19. Spinal fusion, for example, is an orthopedic surgical technique that joins two or more vertebrae using a process called fixation which involves the placement of pedicle screws, rods, plates, or cages to stabilize the vertebrae and facilitate bone fusion. The autografting osteotome 36 is particularly well-suited to forming osteotomies in vertebrae to receive pedicle screws (not shown). A suitably-adapted telescopic stop 54 can be used in conjunction with the osteotome 36, as shown in Figure 19, to limit drilling depth according to a predetermined surgical protocol. Likewise, a suitably-adapted jig (not shown) can also be used in this lumbar application, as well as in other orthopedic applications. Furthermore, the concepts of this invention may be used to prepare holes in solid and cellular materials for industrial and commercial applications, such as in foamed metal or polymeric substrates, to name but a few.

[0068] Turning now to Figures 20-22, an alternative embodiment of the telescopic stop 154 is depicted. In this example, reference numbers corresponding to like features in the preceding examples are offset by 100 for convenience. Thus, the key 156 of Figures 20-22 corresponds to the key 56 of Figures 6-12, the indexing gauge 170 of Figures 20-22 corresponds to the indexing gauge 70 of Figures 6-12, and so forth. In this new embodiment, the indexing gauge 170 is configured to improve the ease with which the axial position of the key 56 can be adjusted, and further to facilitate free rotation of the telescopic stop 154 about the osteotome 36.

[0069] As in the preceding examples, the telescopic stop 154 provides pre-set depth stops at 6mm, 8mm, 10mm, 11.5mm and 13mm of penetration as measured between the stop ring 158 and the apical end 48 of the osteotome 36. While the illustrations depict only one size telescopic stop 154, it will be understood that in practice several sizes of telescopic stops 154 may be made available for applications in which implants of various sizes are placed. For example, the telescopic stop 154 may be offered in sizes of small, medium, large and extra-large. Drills or osteotomes 36 up to a certain small diameter may be accommodated by the small telescopic stop 154, up to a certain medium diameter may be accommodated by the medium telescopic stop 154, up to a certain large diameter may be accommodated by the large telescopic stop 154, and drills or osteotomes 36 of all diameters may be accommodated by the extra-large telescopic stop 154. A typical surgical procedure to form an osteotomy 32 in preparation to receive an implant 34 (Figure 5) will call for a certain final diameter drill or osteotome 36. The smallest possible size telescopic stop 154 will typically be selected to accommodate the final drill size.

[0070] Figure 20 is an exploded view illustrating the manner in which the components of the telescopic stop 154 are operatively coupled with osteotome 36. According to this embodiment, the integral key 156 and indexing gauge 170 components are assembled from opposite ends of the drill or osteotome 36. In particular, the is first slid over the top of the shank 40 so that its spurs 178 will seat into the groove 45. The key 156, on the other hand, is inserted over the apical end 48 of the osteotome body 42 and then into registry with the indexing gauge 170 already locked into position.

[0071] One attribute of this embodiment of the indexing gauge 170 is to facilitate free rotation of the telescopic stop 154 about the osteotome 36. That is to say, the indexing gauge 170 of Figures 20-22 is designed to spin smoothly on the shank 40. This attribute may be accomplished by controlling the design and tolerance of the interface between the central bore 172 of the indexing gauge 170 and the shank 40. By carefully crafting the interstitial features and tolerances, a smooth bearing-like rotation can be achieved.

[0072] In this embodiment, the alternative indexing gauge 170 is notable for its several distinctive features, a few of which will be described presently. Two flats 102 are formed as axially-extending features on diametrically opposite sides of the indexing gauge 170. However, the number of flats 102 is variable; more or less than two sets of flats 102 are possible. Typically, the number of flats 102 will correspond with the number of barbs 186 on the key 156. At the juncture of the flats 102 with each annular rib 182, wedge-like transitional ramps 103 may optionally be formed. That is to say, each rib 182 may be seen as leading into the flats 102 at the transitional ramps 103 which have the appearance of extending the planar faces of the flats 102 across the ribs 182.

[0073] A gripping flange 104 is shown here in the exemplary form of a rim-like feature having opposing discontinuities 106 in its otherwise circular shape. The discontinuities 106 are depicted here as flat-spots, but many other shapes and configurations could be used to enhance grip of the indexing gauge. Just to mention a few alternatives, instead of flat spots the discontinuities 106 could be configured as knurling, crenulations, star-points, as upstanding pins or any other suitable shape that will allow a user to manually restrain the indexing gauge 170 against rotation relative to the key 156. This grip-enhancing feature is especially appreciated by surgeons and technicians whose sense of touch and tactile dexterity may be somewhat reduced when wearing surgical gloves. In the preferred embodiment, the discontinuities 106 are off-set from the flats 102. That is to say, the discontinuities 106 and flats 102 are preferably not aligned on the indexing gauge 170. When viewed from above, if the flats 102 appear at the 12 o'clock and 6 o'clock positions, then the discontinuities 106 will appear at the 3 o'clock and 9 o'clock positions in this example. The advantage of locating the discontinuities 106 out of phase with the flats 102 is to subtly encourage the user to pinch the gripping flange 104 so that their fingertips do not eclipse the flats 102, as shown in Figures 21 and 22. In this manner, the depth stop indicia printed on the flats 102 remains clearly visible during the adjustment process.

[0074] In operative use, the barbs 186 of the key 156 are positioned so as to be into full registry with ribs 82. This condition is perhaps best illustrated in Figure 21. In this operative use condition, the registered barbs 186 of and ribs 82 hold the particular length- adjusted setting of the telescopic stop 154 to enable precise depth drilling in the manner described about.

[0075] Figures 21-22 illustrate the ease with which the axial position of the key 156 can be adjusted by way of the flats 102 and the gripping flange 104. The circumferential width of the flats 102 is matched to the circumferential with of the barbs 186, so that when the barbs 186 are rotated into registry with flats 102 (as in Figure 22), the key 156 can be rapidly slid up and down along the length of the indexing gauge 170 without interaction of the ribs 182. In this manner, the flats 102 form a by-pass ramp for the barbs 186 to avoid sequentially interacting with the longitudinal stations. The flats 102 allow the resilient fingers 184 to slide from any one longitudinal station to another without stopping at intervening longitudinal stations.

[0076] In dental applications, it is common for a patient to receive more than one implant 34 at the same time. Instances of surgeons placing two or three implants 34 at once are very typical. Even though multiple implants 34 may be placed concurrently, it is usually the case that each implant 34 will be a different size and require an osteotomy 32 of different depth. In order to use a telescopic stop 154 in these situations, the surgeon must re-set the position of the key 156 on the indexing gauge 170 for each drill or osteotome 36 that is used in more than one hole. In other scenarios, like sinus lifts for an example, the surgeons may wish to begin a procedure with a shallow depth setting and then progressively increase depth with osteotome 36 diameters. To save time and aggravation for the surgeon during intra-procedure depth changes, the telescopic stop 154 is enabled with quick re-setting capability.

[0077] To affect a change in the desired drilling depth, the axial position of key 156 is adjusted relative to the indexing gauge 170 without removing the indexing gauge 170 from the shank 40. In this alternative embodiment, the surgeon (or an assistant) manually grasps the gripping flange 104 of the indexing gauge 170 between thumb and forefinger as illustrated in Figures 21-22. The discontinuities 106 enhance the tactile grip. Using the thumb and forefinger of the other hand, the user gently pinches the lower cuff 64 region of the key 156. In some cases, it may be desirable to fabricate the key 156 from a rigid yet slightly resilient material so that when pinched, especially below the barbs 186, a slight outward deflection will occur which will help dislocate the barbs 186 from the channels 80. However, in the preferred embodiment, the key 156 is sufficiently rigid such that no discernable deflection will occur under normal handling pressure. The user next rotates the key 156 to the position shown in Figure 22 (typically a quarter turn or -90°) wherein the barbs 186 align with flats 102. The user's secure grasp on the gripping flange 104 assures that the indexing gauge 170 remains stationary relative to the rotating key 156.

[0078] Once the barbs 186 of the key 156 are disengaged from the ribs 82 (i.e., registered with the flats 102), mild axial pressure is applied to move the key 156 to a different longitudinal station on the indexing gauge 170. A desired drilling depth is achieved by aligning the barbs 186 with the corresponding indicia (6-8-10-11.5-13) visible along the flats 102. If too much pressure results in an over-shoot of the desired depth, the user simply reverses the axial force causing the key 156 to move the other axial direction. Once the desired new depth setting has been reached, the user rotates the key 156 another quarter turn (i.e., -90°) so as to re-engage the barbs 186 with the ribs 82 in the desired longitudinal station as shown in Figure 22. The osteotome 36 is now ready for operative use at the new depth setting. In this manner, the key 154 may be re-set multiple times during the course of a surgical procedure or when preforming multiple concurrent procedures on the same patient.

[0079] A very low rotational friction between the telescopic stop 154 and the osteotome 36 is desirable with this embodiment of the indexing gauge 170. Said another way, it is preferred that the rotational friction between the telescopic stop 154 and the osteotome 36 be substantially lower than the rotational friction between the key 156 and the indexing gauge 170. Ideally, in use when the stop ring 158 makes contact at full depth (see Figure 25), the entire telescopic stop 154 will stop spinning while the osteotome 36 continues to rotate at high speed. A motionless telescopic stop 154 will not only avoid abrasion of the stop ring 158 at its point of contact, but will also avoid a situation where the key 156 accidentally shifts on the indexing gauge 170. Advantageously, the vane slots 160 continue to allow a sufficient flow-through of irrigating fluid even when the key 156 is not spinning. [0080] Another unique attribute of this embodiment can be seen in the reduction of the number of locking segments 176. Whereas the preceding embodiment included four locking segments 76, this present embodiment includes only two locking segments 176 of equal size. By reducing the number of locking segments 176, their radial flexibility is substantially reduced. As a direct result, the indexing gauge 170 is more securely retained to the groove 45 in the shank 40.

[0081] Perhaps best seen in Figure 20, the locking segments 176 are formed by a single diametrical slit formed in the top of the indexing gauge 170. The diametrical slit can be placed at any angular orientation, but in the preferred example is located so as to pass through the transitional ramps 103. That is to say, the diametrical slit used to form the locking segments 176 is oriented so as to intersect neither the flats 102 nor the full formation of the ribs 182. By not passing the slit through the flats 102, the real estate needed to portray the depth stop indicia is preserved. And by not passing the slit through the full formation of the ribs 182, frictional contact with the barbs 186 of the key 156 is fully preserved and the possibility for the barbs 178 applying compression to spread the locking segments 176 is avoided. Furthermore, it is desirable, although not mandatory, that the diametrical slit be oriented so as not to intersect the discontinuities 106 on the gripping flange 104 and thereby provide additional grip enhancement during the key 156 adjustment process.

[0082] Another distinguishing characteristic of this embodiment may be seen in the vane slots 160 of the key 156. In this example, the vane slots 160 are composed of two diametrically-opposed oval slots interposed between two diametrically-opposed circular holes. This exemplifies the statements earlier to the effect that the vane slots 160 can take many different shapes and forms. Here, the large oval slots enable a generous flow of cooling spray to pass through. Column strength is preserved via the use of smaller circular holes in-between the large oval slots.

[0083] Turning now to Figures 23-25, the jig 188 is shown in the form of an alternative embodiment. In this example, reference numbers corresponding to like features in the preceding examples are again offset by 100 for convenience. Thus, the guide bushing 190 of Figures 23-25 corresponds to the guide bushing 90 of Figures 13-16, the alignment valley 192 of Figures 23-25 corresponds to the alignment valley 92 of Figures 13-16, and so forth. In this new embodiment, the is configured in a full annular shape. The full annular shape provides an added degree of stability to the abutment step 194, thus enabling it to better help maintain the as-designed semi- cylindrical shape of the alignment valley 192. Also, the added stability enables the axial thickness of the abutment step 194 to be reduced. For example, whereas the axial measure of the abutment step 94 in the embodiment of Figures 13-16 was suggested as 2mm, the axial measure of the abutment step 194 in the embodiment of Figures 23-25 may be reduced to something on the order of 1mm.

[0084] Furthermore, the shape of the guide bushing 190 may be slightly modified in view of the full annular abutment step 194. A low-cut scallop 108 may be used to eliminate or minimize stress-concentrating sharp internal corners where the alignment valley 193 and abutment step 194 would otherwise meet. The scallop 108 extends from the alignment valley 192 so as to partially surround the thin protruding portion of the abutment step 194. This scallop 108 also helps to strengthen the guide bushing 190 so that its shape is maintained even after autoclaving and other high-temperature procedures that might otherwise provoke some dimensional movements. Nevertheless, a substantial majority of the alignment valley 192 remains open and laterally accessible as in the earlier embodiment.

[0085] Also, it will be understood that the size of the guide bushing 190 will be matched to the diameter of the telescopic stop 54. Thus, a small size guide bushing 190 will be used in conjunction with a small size telescopic stop 154; a large size guide bushing 190 will be used in conjunction with a large size telescopic stop 154; and so forth. It must be understood that the dimensional attributes described here and shown in connection with Figures 23-25 are offered as examples only for applications within dental field of use. Of course, other dimensional attributes are possible, especially when the present invention is adapted for use in general orthopedic (i.e., non-dental) applications like those suggested in Figures 17-19, or in altogether non-medical (e.g., industrial) applications.

[0086] 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. Furthermore, particular features of one embodiment can replace corresponding features in another embodiment or can supplement other embodiments unless otherwise indicated by the drawings or this specification.