Patent Application
20140212834
This invention relates to endodontic instruments.
An important endodontic procedure, known as a “root canal” procedure, involves removing organic material from the root canals of an infected tooth and filling the canal with an inert obturating material such as gutta percha gum.
An effective root canal procedure avoids extraction of the infected tooth. In this procedure, a dentist or endodontist utilizes a series of endodontic instruments, for example files, for the debridement, cleaning and sterilization of the root canal. These files are rotated within the canal to clean the canal surfaces, removing debridement (organic) material in the process, facilitating improved irrigation, and in some cases shaping the canal for easier filling with the obturating material.
Root canal preparation, and root canal retreatment (to repair a defective root canal procedure), are typically effected by motor-driven instruments such as files. Retreatment can be defined as a procedure to remove root canal filling materials from the tooth, followed by cleaning, shaping and obturating the canals.
Once the pulp has been removed from the root canal, a smear layer remains. The smear layer is potentially infected, and its removal allows more efficient penetration of intracanal medications into the dentinal tubules and a better interface between the filling material and the root canal walls. A final flush with chelating agents and antiseptic irrigating solutions is needed to remove the smear layer. However, their effectiveness remains limited in the apical area of the prepared canal. This is particularly true for curved root canals and even on single-rooted teeth. Therefore, the improvement of irrigating protocols is essential during root canal treatment in order to achieve better cleaning efficiency especially in the very complex apical area. Currently, several techniques and systems are available and reported to improve final irrigation by irrigant activation and agitation before obturation.
It is thus advantageous to perform the debridement of the canal using an active instrument. For example, U.S. Pat. No. 8,328,552 issued Dec. 11, 2012 to Ruddle et al., which is incorporated herein by reference, describes a flexible, non-metallic activator which vibrates at sonic (1-10 KHz) or ultrasonic (25-30 KHz) frequencies to actively dislodge the smear layer and organic debris from the canal wall, while at the same time irrigating the canal to wash away the debris and sterilize the canal. The disadvantage to such a system is that the efficacy of the sonic-driven activators is not significantly greater than manual agitation of irrigant fluid in the canal by an activator (Caron et al. Effectiveness of different final irrigant activation protocols on smear layer removal in curved canals. Journal of Endodontics 2010 August;36(8):1361-6). Also, an activator made of a flexible non-metallic material similar to Ruddle's in many cases cannot be driven using ultrasonic energy because of the possibility of fracture of the activator.
Ultrasonic-driven activators are available, but they are made of a metallic rigid material; these activators are aggressive and can cause problems, especially in curved canals.
In drawings which illustrate by way of example only a preferred embodiment of the invention,
The present invention provides a motor-driven instrument for cleaning the canal during a root canal procedure, the distal portion of which provides an activator that is effective, safe to use on a tooth and will not fracture in use. Advantageously, the instrument may be driven by the same motor used to drive the endodontic files used in the root canal procedure, which reduces costs by avoiding an additional costly and bulky ultrasonic or sonic device. Thus the invention requires less equipment, less maintenance and less space in comparison with ultrasonic- and sonic-driven activators.
Another advantage is that the instrument may be used in general with the devices used to drive endodontic files for the canal preparation, and more specifically with the same reciprocating movement that is used for the endodontic files in the canal preparation process. Therefore, the procedure becomes simpler with a shorter learning curve and faster (no need to change devices in order to switch between instruments) and easier to learn.
There are further advantages in the embodiments of the instrument in which the activator provides agitating structures for enhancing the agitation of the irrigant and the evacuation of irrigant from the canal, which in its turn allows for a more irrigant to be introduced into the canal. In embodiments that provide openings for irrigant injection through the instrument, this can be effected without removing the activator tip from the canal.
The invention thus provides a cleaning instrument 30 for an endodontic procedure such as a root canal and an apparatus utilizing such an instrument. In the preferred embodiment the instrument 30 comprises a distal portion 40 providing agitating structures 42 which agitate the irrigant to provide a stirring action. These agitating structures 42 may for example comprise small bristles or fins along the surface of the activator. The diameter of the distal portion 40 including such structures is smaller than the diameter of the prepared canal, to allow for agitation of the irrigant fluid and to allow the tip of the activator at the distal portion 40 of the instrument 30 to reach the end of the prepared canal.
As the distal portion 40 of the instrument 30 is used within the root canal, its lateral walls and/or agitating structures will tend to contact and rub against the surfaces of the root canal, to physically enhance the chemical action of the irrigant fluid, but because the instrument 30 is made from a flexible, non-metallic and non-cutting material, this occurs without the risk of damaging the internal walls of the root canal. This rubbing action will help to remove debridement material that is loosely adhered to the canal wall.
In some embodiments openings 42 are provided through which an irrigating fluid can traverse the tip or the wall of the distal portion 40 of the instrument 30 and enter the canal to wash away loosened debris and sterilize the canal. In some embodiments the agitating structures 44 are aligned so as to assist in evacuating irrigant and entrained debris from the canal.
These apparatuses may be adapted to inject irrigant through the wand of the apparatus in any suitable fashion, for example as described and illustrated in U.S. Patent Application No. US2012/0040306 (Johnson) published Feb. 16, 2012, which is incorporated herein by reference.
In the embodiment illustrated the proximal end 32, shown in
In irrigating embodiments the activator at the distal portion 40 comprises at least one orifice 42, preferably a plurality of orifices 42 through which an irrigating fluid pumped from the base unit 14 or an auxiliary pump (not shown) egresses from the distal portion 40 and enters the canal. The tip of the distal portion 40 can be closed with orifices 42 disposed about the side wall of the distal portion 40, as shown in
The activator tip preferably provides agitating structures 44 which physically stir the irrigant to assist in dislodging debris that loosely adheres to the canal wall, and to assist in the evacuation of irrigant from the canal. These structures, for example fins of varying configurations, as shown in
The distal portion 40 comprising agitating structures is preferably formed integrally with the instrument 30, for example in the preferred embodiment shown where the instrument is formed from a material which is non-abrasive and sufficiently soft as to be unable to bind on the canal or otherwise harm the tooth. Instruments 30 having different configurations of distal portions 40 can be easily interchanged as necessary during the root canal procedure by removal from the chuck 16 and replacement with a different instrument. Alternatively, but less preferably, the agitating structures 44 may be formed on a separate tip (not shown) which can be attached to the distal portion 40 of the instrument in any secure rotationally and axially fixed fashion.
For example, without limitation, the activator at the distal portion 40 of the instrument 30 may be smooth-walled (for example conical or frusto-conical) without any abrading structures but formed from a natural abrading material (e.g. non-degrading rubber). Alternatively, the distal portion may be provided with agitating structures 44 such as fins, bristles, embossments and/or other like structures, which result in both more effective release of loosely adhered debris and better agitation of the irrigant fluid; and/or the distal end of the device can have a helically-oriented groove 46 which is advantageously used in both reciprocating and continuous rotary motion of the instrument 30, as shown in
The use of bristles increases the selection of materials from which the distal portion 40 can be formed. Bristles on the distal portion 40 may for example be similar to the device described and illustrated in U.S. Pat. No. 6,981,869, which is incorporated herein by reference, or in published U.S. Patent Application No. 2012/0222229, which is incorporated herein by reference. The bristles are preferably embedded into the distal portion 40 when the instrument 30 is molded or otherwise formed.
The distal portion 40 may alternatively, or additionally, be provided with agitating structures such as axially-, radially- or helically-oriented fins 44 to enhance irrigant agitation in the canal. The shapes and the positions of the fins 44 may depend on the motion of the tip 40; for example, generally radially oriented fins (as shown in
In each of these examples the distal portion 40 may provide orifices 42 for irrigant delivery. Where no orifices 42 are provided, irrigant fluid is fed into the canal by a separate irrigator (not shown), and the agitating structures 44 assist in the evacuation of the fluid from the canal during the root canal procedure, in order to carry away loose debris and contaminants. Where orifices 42 are provided they are interspersed with agitating structures 44, as shown in
A combination of axial and rotary motions would most beneficially employ an instrument 30 having a distal portion 40 providing a combination of such fins 44. The fins 44 can be aligned horizontally on the activator following a helical pattern to enhance the evacuation of the irrigant in a coronal direction (depending on the rotational motion of the distal portion 40). The helical fins 44 can be machined into the distal portion 40, molded integrally with the distal portion 40 or otherwise formed in any suitable fashion.
In the embodiment of
Various embodiments of the present invention having been thus described in detail by way of example, it will be apparent to those skilled in the art that variations and modifications may be made without departing from the invention. The invention includes all such variations and modifications as fall within the scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2806217 | Jan 2013 | CA | national |
