This disclosure relates to the field of medicine and dentistry. More particularly, this disclosure relates to endodontic instruments.
In the field of endodontics, one of the most important and delicate procedures is that of cleaning or extirpating a root canal to provide a properly dimensioned cavity while essentially maintaining the central axis of the canal. This step is important in order to enable complete filling of the canal without any voids and in a manner which prevents the entrapment of noxious tissue in the canal as the canal is being filled.
In a root canal procedure, the dentist removes injured tissue and debris from the canal prior to filling the canal with an inert filling material. In performing this procedure the dentist must gain access to the entire canal, shaping it as necessary. But root canals normally are very small in diameter, and they are usually quite curved. It is therefore very difficult to gain access to the full length of a root canal.
Many tools have been designed to perform the difficult task of cleaning and shaping root canals. Historically, dentists have used a wide multitude of tools to remove the soft and hard tissues of the root canal. Traditionally, these tools, usually called endodontic files, have been made by three basic processes. In one process, a file is created by twisting a prismatic rod of either square or triangular cross section in order to create a file with helical cutting/abrading edges (“K-file”). The second process involves grinding helical flutes into a circular or tapered rod to create a file with one or more helical cutting edges (“Hedstrom file”). The third method involves “hacking” or rapidly striking a circular or tapered rod with a blade at a given angle along the length of the rod, thus creating an endodontic file characterized by a plurality of burr-like barbs or cutting edge projections (“barbed file” or “broach”). Each of these methods produces an instrument having unique attributes, advantages, and disadvantages.
Endodontic files have historically been made from stainless steel, but due to the inherent stiffness and brittleness of steel, these tools can sometimes pose a significant danger of breakage in the curved root canal. More recent designs have attempted to overcome these problems. Some attempt to alter the geometry of the stainless steel file or use a more flexible material, such as nickel-titanium alloys, in order to provide more flexibility. While these approaches have improved the performance of endodontic files, the files still have a tendency to break if over-torqued or fatigued.
Additionally, when a helically fluted endodontic file is used to extirpate a canal, debris tends to accumulate in the helical flutes as the procedure progresses. This accumulated debris can decrease the files efficiency and can eventually prevent the cutting edges on the file from engaging the canal wall. One method for alleviating the debris accumulation is frequent irrigation of the canal. In certain instances, it is preferable to irrigate the canal simultaneously with the extirpation process. However, this can be difficult when the canal is substantially filled with an endodontic file.
What is needed, therefore, is a different geometric approach to create an endodontic instrument which would fare better with regard to torque stresses, fatigue, and other related stresses on such an instrument, limit debris accumulation, and allow for irrigation simultaneously with extirpation of a root canal. Additionally, what are needed are new methods for manufacturing endodontic instruments with such desirable characteristics.
Further features, aspects, and advantages of the present disclosure will become better understood by reference to the following detailed description, appended claims, and accompanying figures, wherein elements are not to scale so as to more clearly show the details, wherein like reference numbers indicate like elements throughout the several views, and wherein:
Another embodiment including an elongated slit 88 is shown in
In various embodiments described herein, additional sub-slits may be cut along the hollow tube. For example, sub-slits may be formed between the spirals of the slit 88 to, for example, increase potential cutting edges and to increase the flexibility of the tube. These sub-slits may be cut in substantially the same direction as slit 88. The sub-slits do not extend to either end of the hollow tube and are preferably shorter than, for example, the notch defined as a pattern 26 shown in
The above embodiments may all be formed from a tubular blank, wherein apertures or slots may be formed in the tube by cutting or other various methods. Cutting of such apertures, slots, and various other portions of the endodontic instruments described is preferably accomplished using a laser. One preferred laser is a femtolaser, which operates at a very high pulse rate with pulses of short duration. Femtolasers are believed to limit heat creation in the tube material and avoid heat-related changes to material properties. However, in alternate embodiments, the instruments of the present invention may be manufactured using electrical discharge machining, water jet cutters, grinding methods, or other suitable manufacturing methods.
It is thought that debris accumulating in the flutes of conventional endodontic instruments account for up to about 50% of the torque exerted on the instrument. By providing an endodontic instrument with a hollow interior, accumulation of debris in the endodontic instruments and canal is limited, since there are no traditional flutes within which debris can become clogged. This characteristic is particularly helpful in embodiments in which debris is actively removed from the hollow core of the instrument as discussed below.
In a preferred embodiment, an endodontic instrument as described above including a substantially hollow core may be attached to a rotary and/or reciprocating hand-piece or other device configured with an evacuation channel located in-line with the hollow core of the instrument, the evacuation channel for evacuating (e.g., by vacuum suction) liquids and other materials from the area where a dental operation is being performed. Thus, as tissue from the walls of the canal, bacteria, or other matter is removed from the canal by the cutting edges, the material is evacuated through channels, into the hollow core of the instrument, into the evacuation channel, and away from the area where an operation is being performed. Alternatively, the drill or other device attached to the endodontic instrument may include a channel for adding a fluid to a location where an operation is taking place such that a fluid could be introduced through the hollow core of the endodontic instrument to provide irrigation, potentially concurrently with an extirpation procedure.
In addition to various instruments and portions thereof, this disclosure includes a method for making an endodontic instrument including the steps of cutting a specifically shaped portion or portions out of a cylinder including a substantially hollow core (e.g., the cylinder 24 shown in
In one embodiment, the cylinder has been cut in such a way that a plurality of arms has been defined as shown, for example, in
An additional step may include attaching a cutting tip 56 to the distal end 40 of the cylindrically-shaped base 42. Alternatively, an additional step may include cutting portions of the cylindrically-shaped base 42 off of the base 42 leaving a plurality of flaps 82. Subsequently, the flaps 82 may be forced toward one another so that the flap edges 84 (or portions thereof) may be attached together by welding, for example.
The instruments and methods described above are preferably used in endodontic procedures such as, for example, root canal extirpation. The instruments can be used in a manner the same as or similar to traditional endodontic files by rotating the instrument within the canal such that the cutting edges remove material from the walls of the canal. The previously described embodiments of the present disclosure are believed to have many advantages over traditional instruments, including simplicity of manufacturing, greater tolerance to fatigue due in part to the hollow nature of the instrument, less susceptibility to fracture when relatively high torque stresses are applied to the instrument, and increased flexibility in part because of the hollow structure of the instrument. For example, when a traditional endodontic instrument is used to remove material from an infected root canal, interior tooth material often becomes lodged into grooves between cutting surfaces along the outer surface of the instrument, causing the instrument to, in effect, jam or otherwise become mired in a particular portion of a tooth. This jamming may result in the fracture of the instrument because of the rapid increase in torque stress. When an instrument as disclosed herein is used, the tooth material has room to move out of the canal through the interior hollow portion of the instrument, decreasing the likelihood of jamming to occur.
In some embodiments of the invention, a hydrophobic coating may be applied to the interior and/or the exterior of the instrument to facilitate debris removal and irrigation.
Furthermore, instruments of the present invention may also be used for obturation to assist in filling the canal or for other purposes in endodontic and dental procedures.
The foregoing description of preferred embodiments of the present disclosure has been presented for purposes of illustration and description. The described preferred embodiments are not intended to be exhaustive or to limit the scope of the disclosure to the precise form(s) disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiments are chosen and described in an effort to provide the best illustrations of the principles of the disclosure and its practical application, and to thereby enable one of ordinary skill in the art to utilize the concepts revealed in the disclosure in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the disclosure as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.
Any element in a claim that does not explicitly state “means for” performing a specified function, or “step for” performing a specific function, is not to be interpreted as a “means” or “step” clause as specified in 35 U.S.C. §112, ¶6. In particular, the use of “step of” in the claims herein is not intended to invoke the provisions of 35 U.S.C. §112, ¶6.
This application claims priority under 35 U.S.C. §119(c) to provisional application Ser. No. 61/451,858, filed Mar. 11, 2011, which is incorporated herein by reference.
Number | Date | Country | |
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61451858 | Mar 2011 | US |