WO1996039983A1

WO1996039983A1 - Orthodontic wire cutter

Info

Publication number: WO1996039983A1
Application number: PCT/US1996/009658
Authority: WO
Inventors: Robert N Staley
Original assignee: Staley, Robert, N.
Priority date: 1995-06-07
Filing date: 1996-06-07
Publication date: 1996-12-19
Also published as: AU6329396A

Abstract

This invention is a plier-like wire cutting tool useful for orthodontic intrao-oral use, wherein wire is cut into a main segment with a rounded end and a surplus segment which is retained by the cutter so as not to be lost within the patient's mouth. Pivotally attached jaw members (32, 34), actuated by handles (28, 30) in scissors-like fashion, have jaws with beaks (36, 38) extending therefrom at a generally perpendicular angle. One beak includes a protruding shelf (42) with a valley (52) extending within and with a nonlinear cutting edge (50) at the interface between the shelf and valley. The other beak includes a second shelf (58) and a protruding shear tooth (62). The two beaks are complementary in that when the handles are actuated to close the jaws, the shear tooth closes upon the wire and forces it onto the cutting edge as the tooth slips into the valley, thereby cutting the wire into a main end and a surplus end.

Description

ORTHODONTIC WIRE CUTTER

FIELD OF THE INVENTION

This invention relates generally to the field of plier-li e cutting tools, and more specifically to plier-like cutting tools used in orthodontic and dental operations.

BACKGROUND OF THE INVENTION

Orthodontic techniques frequently require the use of wires to manipulate a patient's teeth into the desired position. Under many of these techniques metal bands are fastened about certain of the patient's teeth. Attached to these bands are buccal tubes which are located adjacent to the patient's cheeks. A wire is anchored within the patient's mouth by inserting it through a buccal tube, cutting the wire adjacent one end of the tube, and bending the cut end of the wire so that it cannot be withdrawn through the tube. The anchored wire is then connected to clips mounted on the patient's other teeth. The wire thereby exerts a force on the other teeth in order to move them into the desired position. Difficulties with the cutting and handling of the wire complicate the performance of this orthodontic technique. The orthodontist must take care that the sharp ends of the wire, and the tools used to manipulate the wire, do not injure the patient's mouth. The forces applied to the wire when it is cut tend to flatten the ends of the wire and give them sharp edges. This makes the cut wire difficult to insert and remove from buccal tubes and increases the chances of wire cuts and puncture wounds to the patient.

There is also a problem of visibility within the patient's mouth, where cheeks, teeth, and the orthodontic tools themselves may obstruct the view of the area where the wire is to be cut. The anchored wire must be cut at a point closely adjacent to the end of the buccal tube. An extra length of wire may bend, contact the patient's cheeks or gums, and cause irritation. The wire used in orthodontic treatment is made of a high tensile strength alloy and is thus quite difficult to cut. Great cutting forces must be applied in order to cut the wire. This causes surplus wire, which has been cut off of the main wire extending through the buccal tube, to tend to fly away from the cutting tool. This surplus wire may fly down the patient's throat or become "lost" within the patient's mouth, posing a danger to the patient.

Because the orthodontist must generally work in the rear of the mouth, between the cheek and gum, in order to perform the aforementioned techniques, a wire-cutting tool should be designed to operate in this small area. A cutter should be designed so that it will not encounter interference from the patient's cheeks, which may push on the cutter making it difficult to properly position the cutter or hold it steady.

The prior art provides several solutions to these problems. A common cutter design is shown in U.S. Design Patent No. 281,452 to Kurz. This cutter has two cutting members that operate about a pivot, much in the way that common household scissors do. A wire is cut when the handles are actuated to force the cutting members together about the wire.

The cutter disclosed in the Kurz patent operates in compressive fashion, whereby two cutting surfaces meet in opposition to "bite" the wire. Other cutters may operate in shear fashion, whereby the cutting surfaces move adjacent to each other and shear the wire trapped between them.

The cutter disclosed in the Kurz patent is known as a "distal end" cutter. In this type of cutter the beak of the cutter, wherein the cutting edges reside, is bent away from the major portion of the cutter jaws at an angle approximately perpendicular to the plane in which the cutting members rotate. The jaws of the cutter may thus easily be positioned in the mouth adjacent and parallel to the patient's rear teeth, with the beak pointing towards the teeth and with the wire extending between the cutting surfaces. This type of cutter is well suited for use within a patient's mouth because the cutting occurs within a small space. Since it cuts "around the corner" from the major portion of the cutter it does not encounter the interference with the patient's cheeks that a non-distal, "straight-end", cutter would.

Since the high tensile strength of orthodontic wire may cause the surplus end of a wire to fly from the main end after cutting, it is helpful to have some means of catching the potentially injurious surplus end so that it does not become "lost" within the patient. A solution to this problem is disclosed in U.S. Patent No. 3,555,677 to Cusato. This patent discloses cutters which are provided with a shelf area resting on each beak adjacent to the cutting edges. As the cutting edges close on the wire to snip off the surplus end, the shelf areas come together to grip the surplus end so that it does not fly from the cutter. The cutters can then be removed from the patient's mouth with the surplus end retained for proper disposal.

Despite the diverse types of wire-cutting tools used in the orthodontic arts, however, all prior art cutters (both compressive and shear-type) tend to share a common flaw: as the wire is cut, the diameter of the wire is flattened, and sharp corners form on the cut end. The sharp corners heighten the danger of cuts and puncture wounds to the patient's cheeks and gums. Furthermore, the deformed end of the wire makes the wire difficult to insert and remove from buccal tubes. This may result in the orthodontist having to resort to tugging and pushing in order to effect the insertion or removal from the tubes. If the wire slips or suddenly "gives" the force of this tugging or pushing may drive the wire into the patient's oral tissues. In any case, it is possible that the cutting forces may so deform the wire that its insertion and removal from buccal tubes becomes an unnecessarily time-consuming operation unto itself. The prior art does not disclose any means of eliminating the sharp edges of the wire which are produced by cutting. What is desirable, therefore, is an orthodontic cutter which retains the best features of the prior art, including ease of use in the confined space of a patients mouth and retention of cut surplus wire, and which also provides a cut end which is not deformed and sharpened by the cutting process.

SUMMARY OF THE INVENTION

The present invention provides a pliers-like wire cutting apparatus of a size convenient for use in a patient's mouth wherein the cutting apparatus retains the surplus end of the wire after cutting and wherein the main end of the wire adopts a rounded profile after cutting. The rounded profile lessens the possibility that the patient's mouth may be cut or punctured by the cut end of the wire and it greatly facilitates the insertion and removal of the wire from buccal tubes. In accordance with the present invention a wire- cutting orthodontic pliers is comprised of two jaw members. The two jaw members are preferably rotatably connected to each other at a pivot. Each jaw member includes a cutting jaw end and a handle end. The two cutting jaws may be brought together when the jaw members are actuated to rotate about the pivot by bringing the two handles together. The entire cutter is of a size such that it may be easily manipulated within the patient's mouth.

One of the cutting jaws has a beak with a cutting edge and the other jaw has a beak with a shear tooth. These beaks are preferably distally located in relation to the jaws to allow easier intra-oral cutting. The cutting edge and shear tooth define non-linear complementary surfaces which operate in tandem to cut the wire. When the jaws are brought together about a wire the shear tooth forces the wire onto the cutting edge, thereby shearing the wire into a main end, which adopts a profile corresponding to the shape of the non-linear cutting edge, and a surplus end. Preferably the non-linear profile is generally rounded in shape. For example, the cutting edge may have a concave parabolic profile, thereby producing a main end of the wire with a rounded profile.

Preferably shelves are located on each jaw adjacent to the cutting edge and the shear tooth. These shelves close upon the surplus end of the wire after it is sheared, thereby retaining the surplus end so that it may be removed from the mouth and properly disposed of.

A guidance shelf is preferably located adjacent to the shear tooth to aid in positioning the wire between the shear tooth and the cutting edge. When a wire abuts the guidance shelf and the shear tooth it rests entirely between the shear tooth and the cutting edge. An operator may thus use the guidance shelf to assure that the entirety of the main end of the wire will be cut by the cutting edge and shear tooth. Further objects, features, and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a perspective view of the preferred embodiment of the cutter of the present invention.

Fig. 2 shows a perspective view of the cutting edge jaw of the cutter of the present invention.

Fig. 3 shows a perspective view of the shear tooth jaw of the cutter of the present invention.

Fig. 4 is a plan view of the cutting edge jaw of the cutter of the present invention as seen from between the jaws the cutter.

Fig. 5 is an elevation view of the cutting edge jaw of the cutter of the present invention.

Fig. 6 is a plan view of the shear tooth jaw of the cutter of the present invention as seen from between the jaws of the cutter.

Fig. 7 is an elevation view of the shear tooth jaw of the cutter of the present invention. DETAILED DESCRIPTION OF THE INVENTION

A preferred embodiment of a cutter in accordance with the present invention, indicated generally by the numeral 20, is shown in Fig. 1. The cutter 20 includes two jaw members 22,24 which rotate about a pivot 26 when actuated by the force of a human hand on the handles 28,30. The handles 28,30 may be provided with knurling, rubber sleeves, or other means for providing an improved gripping surface. The jaw members 22,24 may be spring-loaded so that they will generally stay in an open position unless actuated to close. This is helpful for pliers-like inventions, which are generally easy to close by hand, but hard to open without the addition of finger loops or the like to the handles.

Opposite one handle 28 is a cutting edge jaw 32. Opposite the other handle 30 is a shear tooth jaw 34. The two jaws 32,34 are brought together when the handles 28,30 are actuated. At the end of the cutting edge jaw 32 is a cutting edge beak 36. At the end of the shear tooth jaw 34 is a shear tooth beak 38. These two beaks 36,38 are preferably distally located from the jaws 32,34, extending from them at a substantially perpendicular angle. These "distal end" type of cutters may be operated with minimum interference from a patient's cheeks. Alternatively, the cutter 20 may be of non- distal end design, wherein the beaks 36,38 are generally parallel to the entirety of the jaw members 22,24. Such a cutter might, for example, be used for cutting wire outside of a patient's mouth, where the distal end design would not be of any significant advantage.

The cutting edge beak 36 is shown in detail in Fig. 2 (in perspective), Fig.4 (in plan view) and Fig 5. (in elevation view) . The cutting edge beak 36 has a cutting edge beak surface 40, which includes a cutting edge shelf 42, a retaining shelf 44, and a complimentary guidance shelf 46. The cutting edge shelf 42 has a cutting valley 48 which is defined by a non-linear cutting edge 50 on the cutting edge shelf 42 and a shear surface 52 which joins perpendicularly to the cutting edge shelf 42 at the cutting edge 50. The shear tooth beak is shown in detail in Fig. 3 (in perspective) , Fig. 4 (in plan view) and Fig. 5 (in elevation view) . The shear tooth beak 38 has a shear tooth beak surface 54, which includes a shear tooth beak shelf 56, a shear tooth shelf 58, and a guidance shelf 60. A shear tooth 62 extends from the shear tooth shelf 58 out onto the shear tooth beak surface 54. The top of the shear tooth 62 is even with the top of the shear tooth beak shelf 58.

When the handles 28,30 are actuated to bring the beaks 36,38 together, complementary surfaces on the cutting edge beak 36 and shear tooth beak 38 move into close parallel relation: the cutting edge shelf 42 and the shear tooth beak shelf 56; the retaining shelf 44 and the shear tooth shelf 58; and the complementary guidance shelf 46 and the guidance shelf 60. The shear tooth 62 extends within the cutting valley 48, coming closely adjacent to the shear surface 52, when the handles 28,30 are actuated.

The shear tooth 62 and the cutting edge 50 provide the shearing force used to cut an orthodontic wire. The shear tooth 62 forces the wire onto the cutting edge 50 and down the shear surface 52 as the handles 28,30 are actuated. The parabolic, rather than straight, cutting edge 50 produces a cut wire with a rounded end instead of a straight end with sharp corners. In order to produce an optimally rounded cut the cutting valley 48 should have a size slightly larger than the diameter of the wire. This allows the entire diameter of the wire to be cut by the cutting edge 50 and shear tooth 62 rather than by adjacent shearing surfaces which would deform the cut end and leave sharp edges.

In a typical orthodontic procedure the cutter 20 is inserted into the patient's mouth between the cheek and the teeth and adjacent to a wire, protruding from a buccal tube, which is to be cut. The cutter 20 is positioned so that the wire rests between the cutting edge beak 36 and the shear tooth beak 38. The handles 28,30 may then be actuated to bring the beaks together. As the beaks 28,30 come together the wire is trapped between the shear tooth 62 and the cutting edge 50 and, as the shear tooth 62 begins to move within the cutting valley 48, shear forces cut the wire into a main end, and a surplus end which is to be discarded.

The main end of the wire, which is the portion of the wire which remains protruding from the buccal tube, is rounded, rather than sharp-edged, due to the parabolic shape of the cutting edge. The surplus end of the wire is grasped between the cutting edge shelf 42 and the shear tooth beak shelf 56, thereby preventing it from flying off and becoming lost in the patient's mouth as it separates from the main end. The cutter 20 remains closed as it is withdrawn from the patients mouth. After the cutter 20 is withdrawn from the mouth the jaw members 22,24 may be opened to release the surplus end of the wire which may be discarded.

Note that the beaks of the cutter 20 must be designed so that when an orthodontic wire is grasped between the cutting edge shelf 42 and the shear tooth beak shelf 56 the space_< between the retaining shelf 44 and the shear tooth shelf 58 must be larger than the diameter of the wire. If this is not the case the main end of the wire will become pinched between the retaining shelf 44 and the shear tooth shelf 58 thereby deforming the main end, defeating the purpose of the invention, and making it impossible to withdraw the cutter 20 form the mouth without first opening the jaw members 22,24, thereby releasing the surplus end. The rounded end of the main wire, produced by the parabolic cutting edge 50, is desirable because it is less sharp than a wire cut with a straight cutting edge and therefore will not irritate a patient's oral tissues to the same extent that a straight-cut wire would. It is also desirable because it is easier to insert and remove from buccal tubes. A straight-cut wire may require substantial pushing or pulling to insert or remove it from a buccal tube. In addition to the discomfort which such pushing and pulling inflicts on a patient, a straight-cut wire might also be driven into the patient's oral tissues if it slips from the buccal tube when such pushing or pulling occurs. If it is desired that the cutter be designed solely to produce a cut end which facilitates insertion and removal of the main end of the wire from buccal tubes, the design of the cutter 20 may be modified so that the cutter 20 produces a main end of the wire with a sharp needle-like tip. Such a cutter 20 would have a triangular cutting valley 48 with a V- shaped cutting edge 50, and a shear tooth 62 with a V-shaped profile rather than a parabolic one. The main end of the wire would become more sharp and needle-like as the angle of the V is made more acute. It is possible that such a cutter 20 could be used to produce a needle-like main end of the wire, which could then be inserted through a buccal tube, and then a cutter 20 which produces a rounded cut could be used to cut the needle-like main end into a rounded main end.

Besides rounded and needle-like cuts, a number of other non-straight cut wire end profiles are possible. All that is required is that the cutting edge 50 be made nonlinear, and that the shear tooth 62 be modified so that it is complementary to the shape of the corresponding cutting valley 48. Since the wire to be cut is generally of a small diameter, and the operating conditions make it difficult to see, it may be difficult to align the wire with the cutting edge 50 so that the cutting edge 50 and shear tooth 62 alone, and no other surfaces, shear the wire. A guidance shelf 60 is preferably provided to overcome this difficulty by providing a means whereby the wire may easily be aligned with the cutting edge. In positioning the cutter 20 the operator places the wire between the beaks 36,38 by sliding the wire along the cutting shelf 58 until the wire abuts the guidance shelf 60. At this point the wire will rest entirely between the shear tooth 62 and the cutting edge 50. The cutter 20 is preferably made of a sterilizable, corrosion-proof metal, such as stainless steel. Since the orthodontic wires to be cut are made of either stainless steel or nickel-titanium alloy, and have a very high tensile strength, the beaks 36,38 (or at least the cutting edge shelf 42 and the shear tooth 62) are preferably made of carbon alloy steel that will maintain a cutting edge after a long period of use. The beaks 36, 38 might be formed of such a material and then attached to the jaws 32,34 by holding screws or other similar means, so that the entire cutter 20 need not be discarded when the cutting edge 50 grows dull. The beaks 36,38 may simply be replaced with a new set.

It is understood that the invention is not confined to the specific embodiments set forth herein as illustrative, but includes all such forms thereof as come within the scope of the following claims.

Claims

CLAIMSWhat is claimed is:

1. An orthodontic wire cutter comprising a first jaw member and a second jaw member and a means for bringing the jaw members together, the first jaw member including a cutting edge beak and the second jaw member including a shear tooth beak, the cutting edge beak including a nonlinear cutting edge and the shear tooth beak including a shear tooth complementary to the cutting edge so that when the first jaw member and second jaw member are brought together the cutting edge beak and the shear tooth beak are brought into close relation such that a wire located between the shear tooth and the cutting edge will be sheared into a main end and a surplus end by the action of the shear tooth forcing the wire onto the cutting edge.

2. The orthodontic wire cutter of Claim 1 wherein the nonlinear cutting edge is parabolic.

3. The orthodontic wire cutter of Claim 1 wherein the nonlinear cutting edge is V-shaped.

4. The orthodontic wire cutter of Claim 1 wherein the cutting edge beak is located distally from the first jaw member and the shear tooth beak is located distally from the second jaw member.

5. The orthodontic wire cutter of Claim 4 wherein the cutting edge beak and the shear tooth beak are generally perpendicular to a plane in which the first jaw member and second jaw member move to be brought together.

6. The orthodontic wire cutters of Claim 1 wherein the cutting edge beak includes a cutting edge shelf adjacent to the cutting edge and the shear tooth beak includes a shear tooth beak shelf adjacent to the shear tooth whereby a surplus end of wire will be retained between the cutting edge shelf and the shear tooth beak shelf when the wire is sheared.

7. The orthodontic wire cutter of Claim 1 wherein the shear tooth beak includes a guidance shelf adjacent to the shear tooth whereby the wire, when positioned abutting the guidance shelf, will rest between the shear tooth and the cutting edge.

8. The orthodontic wire cutter of Claim 1 wherein the means of bringing the jaw members together includes a first handle attached opposite the first jaw member and a second handle opposite the second jaw member and where the jaw members and handles are rotatably connected.

9. The orthodontic wire cutter of Claim 8 wherein at least a portion of the first handle and the second handle is knurled.

10. The orthodontic wire cutter of Claim 8 wherein the first handle and second handle each rest within a rubber sleeve.

11. The orthodontic wire cutter of Claim 8 further comprising a means for opposably maintaining the first and second jaw members, in the absence of an external force on the handles, in a position wherein a wire may be fitted between the cutting edge beak and the shear tooth beak.

12. The orthodontic wire cutter of Claim 11 wherein the means for opposably maintaining the jaw members is a spring.

13. The orthodontic wire cutter of Claim 1 wherein the first jaw member and second jaw member are made of stainless steel.

14. The orthodontic wire cutter of Claim 1 wherein the first jaw member and second jaw member are made of cobalt- carbon steel.

15. The orthodontic wire cutter of Claim 1 wherein the cutting edge beak and shear tooth beak are capable of being removed from the first jaw member and the second jaw member, and capable of being replaced thereon.

16. The orthodontic wire cutter of Claim 13 wherein the cutting beak and shear tooth beak are made of cobalt- carbon steel.

17. An orthodontic wire cutter comprising: a first jaw member, a first handle attached to the first jaw member, a cutting edge beak attached to the first jaw member and having a cutting edge surface with a nonlinear cutting edge located thereon; a second jaw member rotatably coupled to the first jaw member at a pivot point, a second handle attached to the second jaw member opposite of the pivot point, a shear tooth beak attached to the second jaw member and having a shear tooth beak surface capable of moving toward or away from the cutting edge surface when the first and second handles are actuated, the shear tooth beak surface having a shear tooth thereon, the shear tooth being complementary to the cutting edge and located so that when the first and second handles are actuated the shear tooth moves closely adjacent to the cutting edge in such a manner that it pushes a wire located between the shear tooth and the cutting edge onto the cutting edge thereby cutting the wire into a main wire and a surplus wire by means of shear, and with the shear tooth beak surface located so that, when the first and second handles are actuated, it is moved into close parallel relation to the cutting edge surface in such a manner that the cutting edge surface and the shear tooth beak surface may grip the surplus wire located there between.

18. The orthodontic wire cutter of Claim 17 wherein the cutting edge is parabolic.

19. The orthodontic wire cutter of Claim 17 wherein the cutting edge is V-shaped.

20. The orthodontic wire cutter of Claim 17 wherein the cutting edge beak extends from the first jaw member at a generally perpendicular angle and the shear tooth beak extends from the second jaw member at a generally perpendicular angle.

21. The orthodontic wire cutter of Claim 17 wherein the shear tooth beak surface includes a guidance shelf located adjacent to the shear tooth.

22. The orthodontic wire cutter of Claim 17 wherein at least a portion of the first handle and the second handle are knurled.

23. The wire-cutting orthodontic pliers of Claim 17 wherein the first handle and second handle each rest within a rubber sleeve.