WO2002028306A1

WO2002028306A1 - Tissue cutter with integral guide

Info

Publication number: WO2002028306A1
Application number: PCT/US2000/027724
Authority: WO
Inventors: Americo Fernandes
Original assignee: Blacklock, Gordon, Daniel
Priority date: 2000-10-04
Filing date: 2000-10-04
Publication date: 2002-04-11
Also published as: AU2000277565A1

Abstract

A tissue cutter particularly suited for cutting holes for dental anchors. The tissue cutter (10) has a central shaft (14) including a proximal end (16) having conventional connection structure for attachment to a powered rotatable appliance, and a distal end (18) with a forwardly projecting pin (15) which occupies and is guided within a pilot bore (2). The pin has a blunt, preferably spherical, head (18). A cutting blade (20) is mounted on the central shaft (14) between the proximal (16) and distal (18) ends of the shaft. The blade (20) is preferably annular, having sharp edges or cutting teeth (24) facing the distal end (18) of the shaft (14). At least one relief passage (30) communicates between the interior (28) of the annular blade (20) and the exterior thereof.

Description

TISSUE CUTTER WITH INTEGRAL GUIDE Technical Field

The present invention relates to tissue cutters, and more particularly to a tissue cutter having a support pin which is received in a pilot hole. This feature enables the tissue cutter to be pivoted somewhat as the blade bears against material being cut. The novel tissue cutter finds utility in applications where it is desirable to incline the tissue cutter while bearing down on the cutting blade. A principal contemplated use is in the field of dental anchors, where gum tissue must be cut away to install the anchor, and osteosurgery, where pins and other members must be inserted into bone tissue. However, the novel tissue cutter would be useful in many settings where the angle of the cut must be varied from that of the pilot table. Illustratively, it may be necessary in repair and restoration work in fields other than dental and medical fields to accommodate localized areas of material which is not of sufficient strength and good condition to receive fasteners or otherwise support members being attached. Background Art

From time to time, it becomes necessary to install external members into a material which has deteriorated over time or with exposure to a deleterious influence. Frequently, localized conditions cannot be determined until the material is exposed by cutting. In the field of installing dental anchors in the jaw, the most advantageous angle at which the anchor is to be oriented may not be susceptible of being determined until actual cutting commences.

If the dental practitioner drills a pilot hole, then he or she is constrained to the angle of the pilot hole. Should local conditions at the jaw require adjustment of the cutting angle, then inability to do so would threaten the quality of the remedial therapy. A dental tissue cutter is shown in United States Patent

Number 4,787,848, issued to Stanley E. Ross on November 29, 1988 having a circular cutting blade. There is no guide pin as seen in the present invention.

United States Patent Number 5,098,293, issued to Lennart Lόδf et al. on March 24, 1992, describes a machining device for implant work and has a machining blade formed as a spherical member located at the end of a shaft. Although this configuration bears a superficial similarity to the preferred embodiment of the present invention, a significant difference exists in that the spherical member of the present invention is blunt and not capable of cutting.

Also, the present invention has a circular blade located above the spherical member. By contrast, the spherical member of Lόδf et al. is the blade, and no annular blade is present in the device of Lόόf et

al.

United States Patent Number 1 ,216,683, issued to Edwin J. Greenfield on February 20, 1917, describes a hole cutting saw intended for dental implants. The saw has an annular blade with teeth and has relief holes formed in the blade. There is neither a support pin projecting forwardly of the cutting edge of the blade, nor an enlarged blunt head located forwardly of the cutting blade, both being features of the present invention.

United States Patent Number 1 ,333,388 issued to William E. Chester on March 9, 1920, illustrates a dental tissue cutter having a fluted bit projecting ahead of an annular hole cutting blade. The fluted bit drills a pilot bore ahead of the hole cutting blade, but could not accommodate inclination of the hole cutting blade relative to the pilot hole as occurs in the present invention.

None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Disclosure of the Invention

The present invention provides a hole cutting blade which has a projecting support pin at its distal end. The pin is received in a pilot bore drilled into the jaw. The support pin terminates in a possibly enlarged and generally spherical head. The shaft of the pin can be of a diameter reduced from that of the head with the majority of the shaft being smaller than the pilot bore. This relationship enables the cutting blade assembly to be inclined out of alignment with the axis of the pilot bore. When drilling, a dental practitioner is thus afforded an opportunity to adjust direction and orientation of the hole generated by the annular blade. This is especially important in those instances where local conditions at the jaw make it desirable to make such an adjustment. No prior art tool affords this ability.

The head of the pin is blunt, so as not to extend the pilot hole beyond its original depth, or to abrade or pulverize tissue. The shape is preferably spherical so that the novel tissue cutter is readily rotated and inclined to a new position within the pilot bore. The support pin is generally aligned with the pilot bore, with slight deviation accommodated by virtue of the head being rounded and/or of greater diameter than the shaft of the support pin. The cutting blade is preferably annular, having a

cutting surface facing the enlarged head of the support pin. The blade has at least one relief opening communicating between the interior of the annular blade and the exterior thereof, for enabling expulsion of cutting detritus from the interior of the blade. The cutting blade is sharp enough to cut through soft gum tissue, but will not readily cut through bone tissue. The blade is therefore self- stopping.

At its proximal end, the shaft of the tissue cutter is provided with conventional attachment structure so that the tissue cutter can be mounted in a conventional powered driving appliance to rotate the tissue cutter under power.

Accordingly, it is one object of the invention to provide a tissue cutter which seats and supports itself in a pilot hole without drilling the pilot hole deeper.

It is another object of the invention to provide a tissue cutter capable of being inclined from a pilot hole in which it is received.

Another object of the invention is to enable the tissue cutter to expel cutting detritus.

It is a further object of the invention to enable the novel tissue cutter to be employed with a conventional rotating driving appliance. Still another object of the invention is to enable a dental practitioner to modify the angle of a hole being cut from that of an associated pilot hole.

An additional object of the invention is to prevent a dental tissue cutter from penetrating excessively into tissue being cut.

It is therefore an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.

Brief Description of the Drawings

The features of the invention, and its technical advantages, can be seen from the following description of preferred embodiments together with the claims and the accompanying schematic drawings, in which:

Fig. 1 is an environmental cross sectional view of a tissue cutter of the present invention; and

Fig. 2 is a perspective view of the tissue cutter of Fig. 1. Description of Preferred Embodiment

Fig. 1 of the drawings shows a tissue cutter 10 which is particularly suitable for use with a powered rotatable driving appliance (not shown). The tissue cutter 10 can be inserted into a pilot bore 2 formed in a base material, such as gum tissue 6, being cut, and the tissue cutter 10 is slightly inclined from a coaxial relationship with the pilot bore 2. Gum tissue 6 extends downwardly to bone tissue 8. It will be seen that the center line 4 of the pilot bore 2 is not coaxially aligned with the center of the tissue cutter 10. This relationship illustrates the principal advantage of the tissue cutter 10 of the present invention. The tissue cutter 10 comprises a central shaft 14 having a proximal end indicated generally at 16 and a distal end characterized by a blunt head 18. As can be seen in Fig. 1 , the multi-piece shaft 14 is continuous and solid along its length with the majority of the shaft being smaller than the pilot bore. Head 18 is supported on that portion of the shaft 14 that forms the support pin

15. Pin 15 is that portion of the shaft 14 that extends downwardly from the base 17 of a cutting blade 20. The pin 15 is shown as being a separate part that can be press fit into the base 17, or can be integral therewith. The cutting blade 20 is disposed around and fixed to the shaft 14 between the proximal and distal ends of the shaft 14. The blade 20 can be a separate part, or can be unitary with the shaft 14. Blade 20 has a sharp cutting surface 22 with teeth 24 (see also Fig. 2). The cutting blade20 also has an outer lateral surface 21 that has no teeth. Cutting surface 22 and teeth 24 are located at the bottom of an annular cutting portion 26 of the blade 20.

Annular cutting portion 26 has an interior 28 which can become clogged with detritus accumulated during cutting. Two relief passages 30 are formed in the annular cutting portion 26 of the blade 20 so that detritus can be cleared to the outside of the blade 20. Relief passages 30 provide communication between the interior

28 of the blade 20 and the exterior thereof. Arrows 32 indicate flow through the passages 30 of detritus removed from the base material 6 when cutting. The teeth 24 are configured to resist cutting when a hard surface such as that presented by the bone tissue 8 is encountered.

Shaft 14 has a keyed configuration at the proximal end 16. Keyed configuration signifies any configuration which will oppose ineffectual rotation relative to a driving appliance (not shown)when the tissue cutter 10 is coupled to the appliance. In the embodiment of Fig. 1 , the keyed configuration is a flat surface 34 formed in the otherwise cylindrical configuration of the shaft 14. The circumferential groove 36 is also formed at the proximal end 16. Flat surface 34 and groove 36 are employed to couple the tissue cutter 10 to a conventional driving appliance, thus enabling cutting of the material 6. Fig. 2 clearly shows the flat surface 34, the passages

30, the cutting surface 22, and the teeth 24. It will be seen that the shaft 14 has a first diameter indicated at 38. Head ^'18 has a second diameter indicated at 40. The magnitude of diameter 40 is greater than that of diameter 38. This relationship accommodates inclination of the tissue cutter 10 relative to the pilot bore 2, as shown in Fig. 1. It would also be possible for the diameter of the head to be the same as that of the shaft.

Head 18 is rounded, and in the illustrated embodiment mostly spherical apart from where it connects to the pin 15. Although other blunt configurations, preferably including smooth curves, would be acceptable to operation of the tissue cutter 10, a spherical configuration is preferred. Blunt configurations, if employed, could include variable radius curves and even irregular shapes (neither shown). It is to understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments with the scope of the following claims.

Claims

CLAIMS:

1. A tissue cutter for use with a powered tool rotating appliance for cutting tissue (6), especially soft gum tissue, wherein said tissue cutter (10) can be inserted into a pilot bore (2) and can be slightly inclined from a coaxial relationship with the pilot bore, characterized by: a central shaft (14) having a proximal end (16) and a distal end (18), said distal end having a blunt head (18), wherein said central shaft (14) is continuous and solid along its entire length; and a cutting blade (20) that is disposed upon and fixed to said shaft (14) between said proximal end (16) and said distal end (18) of said shaft, wherein said cutting blade (20) has at least one sharp edge (24) for cutting said tissue (6), wherein said sharp edge (24) is remote from said proximal end (16) of said shaft

(14) and faces said distal end (18) thereof.

2. The tissue cutter according to claim 1 , characterized in that said central shaft (14) has a first diameter (38), and said blunt head (18) of said central shaft has a second diameter (40) that is greater in magnitude than is said first diameter (38).

3. The tissue cutter according to claim 2, characterized in that said blunt head (18) of said central shaft (14) is mostly spherical.

4. The tissue cutter according to claim 1 , characterized in that said shaft (14) has a keyed configuration (34) at said proximal end (16).

5. The tissue cutter according to claim 1 , characterized in that said shaft (14) has a circumferential groove (36) at said proximal end (16).

6. The tissue cutter according to claim 1 , characterized in that said cutting blade (20) includes an annular cutting portion (26), including said at least one sharp edge in the form of teeth (24).

7. The tissue cutter according to claim 6, characterized in that said cutting blade (20) has at least one relief passage (30) communicating between the interior (28) of said annular cutting portion (26) and the exterior of said annular cutting portion (26).

8. The tissue cutter according to claim 1 , characterized in that said cutting blade (20) has an outer lateral surface (21) that has no sharp edges.

9. The tissue cutter according to claim 1 , characterized in that said shaft (14) is of multi-section or unitary construction.

10. The tissue cutter according to claim 9, characterized in that said cutting blade (20) is separate from or unitary with said shaft (14).