US20170196658A1 - Apparatus for evacuation of root canal - Google Patents

Abstract

In an endodontic procedure, after the working of a root canal by instruments to remove material and shape the walls of the canal, irrigant is supplied via a microcannula. A vacuum is applied via a tube which is inserted partway down the root canal. The irrigant is supplied in a manner sufficient to ensure delivery to a side vent of the microcannula. The vacuum at the end of tube draws the irrigant and debris up from the apex of the root canal into the tube. The side vent may have a plurality of more round holes, a diagonal slit, or a U shaped slit, or any other shape. The vent opening should not extend more than approximately 0.75 mm from the closed spherical tip of the microcannula, it must be burr free and the opening must be smaller than the internal diameter of the microcannula.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• The present application is a continuation of U.S. application Ser. No. 14/281,639 filed May 19, 2014, which is a continuation of U.S. application Ser. No. 13/274,336 filed Oct. 16, 2011, which is a continuation of U.S. application Ser. No. 11/629,552 filed Dec. 13, 2006, which is a National Stage Entry under 35 U.S.C. §371 of PCT/US05/021039 filed Jun. 14, 2005, which claims priority to U.S. application Ser. No. 11/152,942 filed Jun. 13, 2005, and U.S. Provisional Patent Application Ser. No. 60/579,915 filed Jun. 14, 2004, and U.S. application Ser. No. 11/152,942 is a continuation-in-part of U.S. application Ser. No. 10/387,804 filed Mar. 13, 2003 and also claims priority to U.S. Provisional Patent Application Ser. No. 60/579,915, the disclosures of which are incorporated by reference herein in their entireties.
TECHNICAL FIELD
• The invention is in the field of endodontics, more particularly methods and apparatus used during root canal procedures.
BACKGROUND
• To preserve a tooth that has or could develop a diseased pulp cavity, it is necessary to prevent bacterial proliferation within the root or pulp canal of the tooth by enlarging the canal without excessively weakening the root's wall by using endodontic files, bores, reamers or other instrumentation in order to: 1) mechanically remove as much of the root canal contents as is possible and 2) allow the introduction of irrigants into the root canal space that dissolve and disinfect organic debris, thus minimizing the presence of bacteria, as well as clearing the walls of the root canal of calcific debris created during instrumentation. After completing steps 1 and 2, the root canal is typically filled or obturated with a material such as gutta-percha and a sealer to occlude the pulp cavity and thus seal the root canal. This procedure is referred to as root canal therapy. Irrigation assists in removing debris and necrotic material remaining after the endodontic files, bores, and reamers used during the removing and shaping steps of the procedure. Although, the irrigant preferably is capable of dissolving or disrupting soft tissue remnants to permit their removal, the irrigant may be any suitable liquid such as water or various alcohols. More particularly, although some degree of debridement is preferred, any fluid may be used to flush debris from the root canal. General examples of appropriate irrigants include hydrogen peroxide and sodium hypochlorite. In order to ensure that as much of the debris and necrotic material as possible is removed, the irrigant is typically applied under pressure using a syringe and a needle inserted into the canal as shown inFIGS. 2A and 2B. However, as reported in Endodontics, 5th Edition, by John I. Ingle and Leif K. Bakland published June 2002, pages 502-503, it is important that the needle fit loosely in the canal to allow backflow. It is also reported that there is little flushing beyond the depth of the needle unless the needle is bound in the canal and the irrigant forcibly ejected, which is undesirable due to the danger of an irrigant such as sodium hypochlorite breaching the apex of the canal and entering the periapical tissue. However, unless the end of the needle is near the apex, the portion of the canal from the apex to the end of the needle cannot be effectively irrigated. But placing the end of the needle near the apex increases the likelihood of the irrigant, which is applied under pressure, entering the periapical tissue. This can be a source of post treatment endodontic pain for the patient. Furthermore, if a significant quantity of an irrigant like sodium hypochlorite is accidentally injected into the periapical tissue, morbid clinical complication can occur including excruciating pain, immediate swelling (ballooning) of the tissue, and profuse bleeding.
• Existing techniques attempt to address this problem by using very small needles to get close to the apex while still fitting loosely in the canal to allow backflow or using an instrument to move some of the irrigant towards the apex with the irrigant no longer under pressure. However, neither technique completely solves the problem. Even the tip of the smallest needles that deliver irrigants under pressure must be kept a safe distance (approximately 4-6 mm) away from the apex in order to avoid accidentally forcing irrigants into the periapical tissue. This safety issue most often results in an area or zone between the apex and needle tip devoid of irrigant. Use of an instrument to force the irrigant through this zone towards the apex is very time consuming and also does not guarantee that the irrigant has flushed the canal all the way to the apex without going too far.
SUMMARY OF THE INVENTION
• The present invention addresses the prior art problems of inadequate delivery of the irrigant to the apex of the canal resulting in an incomplete cleaning of the canal and penetration of the irrigant past the apex into the periapical tissue resulting in treatment complications. According to the invention, after the working of the canal by instruments to remove material and shape the walls of the canal, a cannula is inserted into the canal extending to about 5 mm from the apex and a vacuum is applied which begins to suck up the debris inside the canal. As this vacuum is applied, a small tube used to deliver irrigant is placed just inside the coronal opening of the root canal. Irrigant is passively flowed into the opening of the root canal, but not under pressure. As the irrigant is supplied, it is drawn to the source of the vacuum causing it to cascade down the walls of the root canals, into the tip of the cannula and out through the vacuum system. After several minutes of irrigant cascading down the canal walls, the cannula is removed and a second, smaller cannula with a hole in its wall near the tip is inserted into the canal until it virtually touches the apical tissue, but unlike the prior art, extending it past the apex does not cause irrigant to enter the periapical tissue because as soon as the hole enters the periapical tissue, since it is no longer in an open space, the vacuum created by the cannula is not present. In an alternate embodiment, instead of delivering irrigant via the cannula and applying a vacuum to the microcannula, the irrigant may be supplied via the microcannula. In this embodiment, a vacuum is applied via a tube which is inserted partway down the root canal. Tube and microcannula pass through a material created by a standard dental filling material of a composite nature which provides a seal at a position near the top of the coronal opening. The irrigant is supplied in a manner sufficient to ensure delivery to the side vent of the microcannula. The vacuum at the end of tube draws the irrigant and debris up from the apex of the root canal into the tube.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a cut away side view of a tooth showing its root canal and periapical tissue.
• FIGS. 2A and 2B show a prior art endodontic irrigation system.
• FIG. 3A is a cut away side view of a tooth showing a first cannula and fluid delivery tube.
• FIG. 3B is an expanded view taken alongline3b-3bofFIG. 3A.
• FIG. 4A is a cut away side view of a tooth showing a second cannula and fluid delivery tube.
• FIG. 4B is an expanded view taken alongline4b-4bofFIG. 4A.
• FIG. 5 is a cut away side view of a tooth showing an alternate embodiment of the invention illustrated inFIG. 4A.
• FIGS. 6A-6E show alternates embodiments of the side vent used bymicrocannula41.
• FIG. 7 shows a finger piece for use with the invention.
• FIG. 8 shows how the finger piece ofFIG. 7 is used.
• FIG. 9 shows a master delivery tip with syringe for use with the invention.
• FIG. 10 shows how the master delivery tip ofFIG. 9 is used.
• FIGS. 11A and 11B show the detail of a macro cannula or cannula for use with the invention.
• FIG. 12 shows a handle which may be used to hold the macro cannula shown inFIGS. 11A-11B.
DETAILED DESCRIPTION
• FIG. 1 illustrates a cutaway portion of ahuman tooth11 as it may appear after a portion of a root canal procedure has been completed, namely wherein as much of the pulp material as is possible has been removed by instrumentation. Thetooth11 includes acrown portion13 which is generally the exterior portion extendingpast gums15. The interior portion of the tooth extending past the other side ofgums15 is referred to as theroot17. In approximately the middle of the root extending almost the entire length of the root is theroot canal19 which extends from oneend21 near the crown portion of the tooth to an apex23 at the tip ofroot17. As shown inFIG. 1, the non-visible portion oftooth11 extendingpast gums15 is surrounded byperiapical tissue25.
• Of course, prior to the initiation of the root canal procedure, theapical foramen27 located at or very near theroot apex23 is the only opening into the root canal.
• After the instrumentation phase of the root canal procedure has been completed, there is a large quantity, both in terms of size and amount, of debris within the root canal.
• According to the present invention, after the instrumentation step, cleansing of the root canal is performed in two phases. The first phase is referred to as gross evacuation of the coronal portion of the root canal which is the portion of theroot canal19 beginning approximately 4-5 mm fromapex23. The second phase is referred to as apical evacuation for cleaning the final 4-5 mm of the root canal.
• Referring now toFIG. 3A, the methods and apparatus used for the gross evacuation of the coronal portion of the root canal will now be explained. Acannula31 is inserted into the canal to apoint33 approximately 4-5 mm from the apex as seen inFIG. 3B. A suitable cannula for this purpose is a soft plastic cannula such as part number UP0341 available from Ultradent Products, Incorporated located in South Jordan, Utah. Of course, any comparable device may be used for this purpose. A vacuum is applied to the cannula as is well known in the art which results in debris being sucked up into the cannula. Specifics of asuitable delivery tube35 and vacuum system are well known to persons skilled in the art.
• Afluid delivery tube35 is placed at the top of the coronal opening of the root canal atend21 as shown inFIG. 3A and the desired irrigant is supplied byfluid delivery tube35. A suction exists atpoint33 of the cannula by virtue of an opening in the end of the tube adjacent to point33 and the applied vacuum which results in the irrigant and remaining debris being drawn to the hole in the end of cannula atpoint33. This irrigation and suction results in a nearly complete cleaning of the upper portion of the canal, i.e., the portion extending from the tip of the cannula atpoint33 through the entire length of the canal to end21. This occurs because as the irrigant is delivered via the delivery tube, the irrigant fills the root canal space combines with the debris and together are sucked down the root canal by virtue of the vacuum created at the end of delivery tube atpoint33 and then up throughcannula31 by virtue of the vacuum created. This step normally takes several minutes to complete depending on the size of the root canal space. For example upper canine teeth have larger root canal spaces than lower incisors and require a longer initial irrigation. At the end of this phase the irrigant will be clear and devoid of gas bubbles formed by the dissolving necrotic tissue as well as particulate matter remaining from instrumentation.
• It should be noted that although some irrigant may gopast end33, the 4-5 mm distance fromapex23 is sufficient to prevent any irrigant from reachingperiapical tissue25.
• The gross evacuation of the canal debris in the upper portion of the root canal is critical to the proper completion of phase two since a much smaller tube is used to evacuate the apical portion, i.e., the bottom 4-5 mm of the root canal. This is because the debris in the upper portion of the root canal, prior to the evacuation performed by phase one, includes particles of a size which would clog the smaller opening of the microcannula which is inserted into the apical portion of the root canal.
• Phase two of the procedure will now be described with references toFIGS. 4A and 4B. In phase two, amicrocannula41 is inserted into the root canal extending to the apex23 as best seen inFIG. 4b.Microcannula41 is typically made of a metallic material such as stainless steel or titanium and in one embodiment, has an outside diameter of 0.014 inches. Itstip43 is welded shut and rounded and includes a side vent approximately 0.75 mm long beginning at a point approximately 0.5 mm from the end oftip43.
• Of course, the foregoing dimensions and materials are provided by way of example of a specific embodiment. What is important is thatmicrocannula41 be sized so as to be able to fit into the canal so that it extends substantially completely to apex23 withside vent45 extending as close to the end of the root as possible but without extending into the periapical tissue. Further, microcannula41 should be sized so that there is close contact between the root canal wall in the apical portion and the microcannula. This is to ensure that some of the irrigant is drawn to the end ofmicrocannula41 by capillary action.
• As was the case in phase one, irrigant is delivered viadelivery tube35 and a vacuum is applied tomicrocannula41. In this manner, irrigant is drawn down into the root canal and into the apical portion of the root canal, that is, the bottom approximately 4-5 mm portion of the canal ending atapex43. Sincetip43 is closed, irrigant is drawn intovent45 and does not extendpast tip43 and cannot be drawn intoapical tissue25 due to the vacuum which exists atvent45. By this technique, the irrigant flushes the apical portion of the root canal, removing out any remnants of debris which still exist in a manner which does not allow the irrigant to enter the periapical tissue.
• Additionally, and importantly, in theevent microcannula41 is accidentally forced into the periapical tissue, the side vent will become obstructed by the tissue and the vacuum which exists in the root canal ceases to exist. Since the irrigant in the canal is not under pressure, the irrigant will cease to be withdrawn bymicrocannula41 indicating to the practitioner that the microcannula has extended too far and needs to be withdrawn back into the root canal space slightly, up to the point when the side vent is not in the periapical tissue at which point the irrigant again begins to be withdrawn.
• In an alternate embodiment, and referring now theFIG. 5, instead of delivering irrigant viadelivery tube35 and applying a vacuum tomicrocannula41, the irrigant may be supplied via the microcannula. In this embodiment, a vacuum is applied via atube51 which is inserted partway down the root canal.Tube51 andmicrocannula41 pass through a material created by a standard dental filling material of a composite nature (like the material used in white dental fillings) or alternately a standard dental impression material usually made of a silicone nature which provides a seal at a position near the top of the coronal opening. The irrigant is supplied in a manner sufficient to ensure delivery to theside vent45 of the microcannula. The vacuum at the end oftube51 draws the irrigant and debris up from the apex of the root canal into the tube.
• In this alternate embodiment, the flow of the irrigant may be reversed from apex to crown by placing the microcannula adjacent to the apex, installing a vacuum tube into the canal near the coronal portion and sealing the canal coronally such that both and microcannula and vacuum tube are below the seal, with the vacuum tube being positioned more coronally. As a vacuum is applied to the coronal tube, irrigant is allowed to be drawn into the canal via the microcannula, then up the walls into the vacuum tube.
• Referring now toFIGS. 6A-6E, side vent45 instead of having a generally oblong shape as shown inFIG. 4B, may have a plurality of more round holes as shown inFIGS. 6B and 6C, a diagonal slit as shown inFIG. 6D or a U shaped slit as shown inFIG. 6E, or any other shape. In theFIG. 6B embodiment, the holes actually extend around the circumference of the microcannula. The diameter of the microcannula is 0.318 mm and the distance between the tip of the microcannula and the bottom of the hole nearest the tip is 0.22 mm. In one embodiment, the opening should not extend more than approximately 0.75 mm from the closed spherical tip of the microcannula, must be burr free and the opening must be smaller than the internal diameter of the microcannula to block any particles which clog the microcannula. The reasons the openings must be burr free is that the space where the microcannula is inserted is extremely restricted, and any burr extending from the opening is likely to scrape the dentin from the wall of the root canal and the resulting debris could clog the side vent opening(s). Usually, microcannula41 is coupled directly to a tube used to provide the vacuum or supply the fluid.
• FIG. 7 shows a finger grip handle71 used to hold microcannula41 (shown in shadow line). The finger grip handle has anopening73 into which microcannula41 is inserted. Asecond opening75 arranged 90° from opening73 receives a tube (shown in shadow line) which is connected to a device which produces the required vacuum or supplies the required fluid.Ridges79 provide a grip to assist holding the handle between two fingers as shown inFIG. 8. Given the relatively small dimensions ofmicrocannula41 and the difficulty of maneuvering the microcannula within the confines of the mouth to perform the desired procedure, finger grip handle71 provides extra leverage not available without the handle. In a preferred embodiment, finger grip handle is made of titanium. The two openings are sized to so that the microcannula and vacuum or fluid delivery device are held by friction.
• FIG. 9 shows a master delivery tip. The delivery tip includes ametal tube91 set into a molded fixture made of non-reactive plastic like nylon or polypropylene that is inserted on a standard luer lock fitting. The molded fixture holds a flexibleplastic tube93 non-reactive plastic like PVC over the metal tube, the other end being attached to a vacuum pump (not shown). During clinical use the clinician is able to add a fluid into the access cavity preparation of a root canal. When the level of the fluid being appliedtube91 reaches the top of the access cavity preparation, the excess is sucked away by a vacuum applied totube93 rather than spilling into the oral cavity (mouth). This feature allows the dentist or dental assistant to maintain a constant level of fluid in the root canal access cavity and is helpful throughout all aspects of root canal preparation including instrumentation and irrigation.FIG. 10 shows this operation wherein the fluid being applied is concurrently sucked away.
• FIG. 11A shows a specific design of acannula95 which may be used ascannula31. Atop portion99 which is 5.0 mm in length has a slight taper for fitting into an opening in ahandle97 shown in shadow line inFIG. 11A and in more detail inFIG. 11B. Amiddle portion101 which is 7.5 mm in length tapers to an outside dimension of 1 mm. Athird portion103 tapers from 1 mm to 0.55 mm at its end. The inside dimension at this end is 0.36 mm. While it is preferable that there be no flash at the end of the third portion, there is a 5% of inside diameter surface area maximum flash permitted at this point, since anything larger would serve to trap canal debris.
• FIG. 12 shows handle97 havinghead105 sized to fit the top end of cannula95 (ormicrocannula cannula41 or31) by friction. Raisedelements107 provide a finger grip. The opposite end109 of handle106 is sized to accept a tube from a vacuum unit (not shown).

Claims (17)

What is claimed is:

1.-7. (canceled)

8. A method for evacuating a root canal of a tooth, said tooth having a coronal end with an open access cavity and an apex end, the method comprising:

delivering a fluid into said root canal at said coronal end of said tooth;

inserting a cannula into said root canal such that a tip of said cannula is located in an apical third of said root canal; and

evacuating said fluid from said root canal through said cannula to cause fluid flow in a direction from said coronal end toward said apex end.

9. The method ofclaim 8 wherein inserting said cannula positions said tip of said cannula in an apical portion of the root canal.

10. The method ofclaim 8 wherein inserting said cannula positions said tip of said cannula within 5 mm of the apex end.

11. The method ofclaim 8 wherein, prior to inserting the cannula into said root canal, the method further comprises:

inserting a second cannula larger in diameter than said cannula into said root canal nearer said coronal end of said tooth than said cannula; and

evacuating said fluid from said tooth through said second cannula.

12. The method ofclaim 11 further comprising:

evacuating said fluid from said coronal end of said tooth during evacuating said fluid from said root canal through said cannula.

13. The method ofclaim 8 further comprising:

evacuating said fluid from said coronal end of said tooth during evacuating said fluid from said root canal through said cannula.

14. The method ofclaim 8 wherein inserting said cannula includes inserting said tip of said cannula through an apical foramen of said root canal and then withdrawing said tip of said cannula to a position in said root canal at which evacuating said fluid from said root canal through said cannula starts.

15. The method ofclaim 8 wherein evacuating said fluid through said cannula includes evacuating said fluid through one or more openings that are positioned around the circumference of said cannula.

16. The method ofclaim 15 wherein said one or more openings are each smaller than the internal diameter of said cannula.

17. The method ofclaim 8 further comprising:

providing a source of vacuum at said open access cavity for evacuating said fluid from said coronal end of said tooth.

18. A method for evacuating a root canal of a tooth, said tooth having a coronal end with an open access cavity and an apex end, the method comprising:

supplying a fluid to said root canal;

inserting a cannula into said root canal; and

evacuating said fluid from said root canal to cause fluid flow near an apical third of said root canal.

19. The method ofclaim 18 wherein evacuating said fluid causes fluid flow near an apical portion of said root canal.

20. The method ofclaim 18 wherein inserting said cannula includes positioning a tip of said cannula near an apical portion of said root canal.

21. The method ofclaim 18 wherein evacuating said fluid evacuates fluid through said cannula.

22. The method ofclaim 18 wherein supplying said fluid includes delivering said fluid at said coronal end of said tooth.

23. The method ofclaim 18 wherein, prior to inserting the cannula into said root canal, the method further comprises:

inserting a second cannula larger in diameter than said cannula into said root canal nearer said coronal end of said tooth than said cannula; and

evacuating said fluid from said tooth through said second cannula.

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