GB2074451A - Flexible dental drills - Google Patents

Abstract

An endodontic tool has a flexible resilient shaft (10) with a tapered end (16) which may be fluted. The shaft is very thin (less than 0.5 mm) and is capable of curving to follow the internal contour of a curved tooth root canal, of maintaining that curve in the canal when rotated and of returning to a straight configuration when removed. A diamond coating over part of the shaft provides cutting means giving a smooth finish to the inside of the walls of the canal. Smooth walls facilitate cleansing, sterilization and sealing of the canal. <IMAGE>

Description

SPECIFICATION Endodontic tool The present invention relates to endodontic tools for example drills used in dentistry, and particularly to endodontic drills used for root canal dentistry.

The problem involved in root canal dentistry is to provide a properly cleaned and shaped root canal for the work that is to be done. The canals are very narrow and tortuous and are difficult to develop and shape to receive a filling material.

Root canals are normally less than one half of a millimeter in diameter and are filled with soft tissue or dead tissue. The canal is a cylindrically shaped passage from the top portion of the tooth down the bottom of the tooth where the canal exits to the physiological system of the body. The length of the canal will vary with the size of the tooth, normally from about 10 to 23 millimeters in length.

The standard procedure, where root canal work is necessary, is to open the tooth with a regular burr (sometimes spelled bur) type instrument or drill.

Then to go into the exposed root canal with either manually operated or mechanically driven stainless steel or tungsten carbide drills.

The operation varies and may be a rotary movement, a quarter turn rotation and also an up and down movement or longitudinal movement. If manually operated, this motion is done by hand.

A drill used at present for such work is a stainless steel fluted drill. This stainless steel fluted drill is used to clean out the canal, either by manual means by hand, by instrumentation, or by mechanically driven means.

An endodontic tool may be made by taking a triangular or square shaped shaft and twisting it on itself so that it creates longitudinal spiral flutes. A handle is usually attached at one end for manual operation. Such fluted tools create a lot of rough internal surfaces in which it is difficu It to maintain sterility and also difficult to properly seal the canal.

Hence they are not very satisfactory for proper root canal dentistry.

According to the present invention there is provided an endodontic tool comprising a shaft having a tapered end and cutting means formed on a portion of the surface of the shaft, the shaft being of such flexibility and of such resilience that it is capable of (a) assuming a curved configuration to follow the internal contour of a curved tooth root canal, (b) maintaining a curved configuration following the contour of a curved root canal when the shaft is rotated, and (c) returning to a straight configuration when not constrained by a curved root canal.

The shaft may be of stain less steel, for example containing 12 to 24 percent chromium and 0.2 percent carbon steel.

The tapered end may be plain or of a screw or fluted configuration. The latter provides a lead for entering and progressing forward in root canals in human teeth.

The cutting means is preferably a diamond coating which may cover 10 to 12 mm of the length of the shaft. The diamond-coating may be impregnated or attached by adhesives, electrolytically applied, sintered, or attached by any other standard method.

A tool may be constructed according to the present invention to create a smooth surface area as, in addition to preparing the cylindrical canal, it has a honing action. The smooth interior surface of the repared cylindrical root canal then facilitates cleansing, sterilization and sealing of the canal.

Known dental tools tend to be very thick and inflexible.

The tool of the present invention is very flexible and preferably less than one-half of a millimeter in diameter. This helps it to follow the curve of root canals in a tooth. The tool may be somewhat conical in shape.

The endodontic tool of this invention is superior to present tools, in that present tools tend to create grooves and rough areas in the walls of the cylindrical-like canal, whereas the tool of the present invention when coated with diamond particles provides a honed-like smooth surface. Rough or grooved walls set up conditions that develop voids between the filling material and its interface with the walls of the canal. This can then lead to leakage and eventual failure of the root canal treatment.

The tool of the invention may be operated manually or be mechanically driven.

For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which: Figure lisa pictorial view of an endodontic drillfile with a plain tip; Fig. 2 is a pictorial view of an endodontic drill-file with a fluted tip.

Referring to the drawings and particularly to Fig. 1, an improved endodontic drill-file with a plain tip is shown at 10. In Fig. 2 an improved endodontic drillfile with a fluted end is shown at 110.

It is to be noted that illustrated size ofthe drill-files 10 and 110 in the drawings is many times the size of the actual drill-files which have shafts 14 and 114 respectively of less than one-half millimeter in diameter.

Fig. 1 is one embodiment and Fig. 2 is a second embodiment.

Turning now to Fig. 1, the drill-file 10 has a thin flexible shaft 14 of which a cutting section 20 is coated with diamond particles securely attached to the thin flexible shaft 14. Shaft 14 is slightly tapered toward the plain conical end or tip 16. A short portion of the shaft 14 at the plain conical end or tip 16 may be an uncoated section 18.

Regarding the thin flexible shaft 14 of drill-file 10, it is to be noted that it is of a flexible elastic material having a memory to return to the straight position from the curved position which it must take, and which it is capable of taking, when it is inserted in a curved root canal. In addition, it is to be noted that this drill4ile must also have this memory while rotating in the curved position in the curved root canal. This rotation transfers the curvature prog ressively in small increments around the periphery of the drill-file shaft 14. When withdrawn from the curved root canal the memory within the flexible shaft 14 returns the drill-file 10 to its original straight configuration.

It should be understood that the length ofthe uncoated section 18 may vary or may be coated the same as the cutting section 20. Such variation is within the scope and intent of this invention.

Likewise it should be noted that the length of the cutting section20 that is coated with diamond particles may extend along the thin flexible shaft 14 for a greater length than illustrated on the drawing. Such variation is also within the scope and intent of this invention.

The coating of diamond particles on the cutting section 20 makes it possible to not only cut the interior surfaces of the actual root canal of the tooth, but hones the surface to a very smooth finish.

At the end of shaft 14, opposite from the aforementioned conical end or tip 16, the shaft 14 is affixed within a conventional knurled cylindrical head 12 for holding the flexible shaft 14 and arranged to be chucked for a mechanical instrument drive or grasped for manual manipulation. Motion may be either in a rotary direction or in a longitudinal direction. It may also be operated in the reciprocating quarter-turn motion.

The shaft 14, which is normally approximately 25 millimeters long and made of stainless steel, is tapered to provide a diametrical increase of approximately 0.02 millimeter per millimeter of shaft length. The shaft 14 is normally less than 0.5 millimeterattheconical end ortip 16, and increases by the taper to the knurled cylindrical head 12.

The conical end or tip 16, the included angle of which is approximately 75 , has the uncoated section 18 adjacent to it. The uncoated section 18, if uncoated, is approximately one millimeter in length.

The cutting section 20 normally approximately 15 millimeters in length, but as aforementioned may be extended.

The diamond particles applied to the cutting section 20 may be applied electrolytically or by other suitable means.

The present invention permits not only a drilling action, but also a honing action to produce the smooth surface on the inside of the canal. The present invention permits a filing action in addition to the drilling action which is a distinct improvement over present endodontic drills.

The second embodiment shown in Fig. 2 is generally similar to the first embodiment in Fig. 1 and simi lar teachings of drill-file 10 apply to drill-file 110, except for the conical end or tip 16 and the uncoated section 18 which will be described hereinafter.

Drill-file 110 consists of a tapered shaft 114, a cutting section 120 with a coating of diamond particles, and the shaft 114 secured or held in a knurled cylindrical head 112, all of similar construction and configuration to the comparable structure and configuration of drill-file 10.

At the end of the shaft 114 of drill-file 110, opposite the end where the knurled cylindrical head 112 is located, the shaft 114 is configured into a fluted end 118 that terminates in a pointed end 116. The fluted end 118 and pointed end 116 are not coated with diamond particles.

The fluted end 118 provides a means establishing a lead for entering and progressing forward in a root canal when the tooth structure is such that a plain end, such as conical end or tip 16 on drill-file 10, will not advance easily. The length of the fluted end may vary from approximately two millimeters or longer.

It should be noted that since human teeth vary in size and consequently the actual root canals will vary, the drill-files 10 and 110 may be provided in a range of diameter sizes of 0.10 millimeter to 1.50 millimeter by 0.05 millimeter increments. Such variation is within the scope and intent of this invention.

Accordingly, modifications and variations to which the invention is susceptible may be practiced without departing from the scope and intent of the appended claims.

Claims (8)

1. An endodontic tool comprising a shaft having a tapered end and cutting means formed on a portion of the surface of the shaft, the shaft being of such flexibility and of such resilience that it is capable of (a) assuming a curved configuration to follow the internal contour of a curved tooth root canal, (b) maintaining a curved configuration following the contour of a curved root canal when the shaft is rotated, and (c) returning to a straight configuration when not constrained by a curved root canal.

2. An endodontic tool as claimed in claim 1 wherein the shaft is formed of flexible elastic stainless steel.

3. An endodontic tool as claimed in claim 1 or 2 wherein the shaft is generally tapered.

4. An endodontic tool as claimed in claim 1,2 or 3 wherein the cutting means comprises diamond particles attached to said shaft.

5. An endodontic tool as claimed in any one of the preceding claims wherein said tapered end is of a generally conical shape to provide a lead for said shaft.

6. An endodontic tool as claimed in any one of claims 1 to 4 wherein said tapered end is fluted and provides an advancing lead for said shaft.

7. An endodontic tool as claimed in any one of the preceding claims comprising holding means for said shaft, said holding means being capable of use for manually manipulating said shaft in a reciprocating rotary, or longitudinal direction and also for attachment to means for mechanically driving said shaft in a reciprocating, rotary as well as longitudinal direction.

8. An endodontic tool substantially as hereinbefore described with reference to Figure 1 or Figure 2 of the accompanying drawings.