U.S. patent number RE35,070 [Application Number 08/126,798] was granted by the patent office on 1995-10-24 for root canal filling device including releasably reusable inserter tool.
This patent grant is currently assigned to John T. McSpadden. Invention is credited to Bernard A. Fitzmorris.
United States Patent |
RE35,070 |
Fitzmorris |
October 24, 1995 |
**Please see images for:
( Certificate of Correction ) ** |
Root canal filling device including releasably reusable inserter
tool
Abstract
A root canal filler assembly including a single use obturator
and a multiple use elongate inserter tool is disclosed. The
oburator includes a metallic core and a plasticizable coating,
preferably formed of gutta percha. One end of the metallic core
extends beyond the plasticizable coating to support a connector
assembly. The multiple use inserter tool is removably connectable
to the oburator to insert, remove, adjust, and reposition the
obturator in a root canal. The inserter tool includes at one end a
connector assembly which engages the obturator and at the other end
a handle to facilitate manipulation of the assembly by the dentist.
The elongate inserter tool may be reused as required, both to
remove or reposition a previously inserted obturator and to insert
additional obturators in other root canals. A method of filling and
sealing a root canal employing the disclosed root canal filler
assembly is also provided.
Inventors: |
Fitzmorris; Bernard A.
(Washington, DC) |
Assignee: |
McSpadden; John T.
(Chattanooga, TN)
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Family
ID: |
23422063 |
Appl.
No.: |
08/126,798 |
Filed: |
September 24, 1993 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
361438 |
Jun 5, 1989 |
05051093 |
Sep 24, 1991 |
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Current U.S.
Class: |
433/224 |
Current CPC
Class: |
A61C
5/50 (20170201); A61C 5/55 (20170201) |
Current International
Class: |
A61C
5/04 (20060101); A61C 005/02 () |
Field of
Search: |
;433/81,102,224 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Thermafil, "The Perfect Apical Seal", (1 page brochure). .
Thermafil, "Commonly Asked Questions about Thermafil", (1 pg.
brochure). .
Thermafil, "Directions for Use of Thermafil", (1 page
brochure)..
|
Primary Examiner: O'Connor; Cary E.
Attorney, Agent or Firm: Luedeka, Neely & Graham
Claims
I claim:
1. A root canal filter assembly for inserting a biocompatible
filler material into the canal of the root of a tooth to fill and
seal the canal following removal of the tooth pulp and treatment of
the canal, said filler assembly comprising:
(a) single use filler means conforming substantially to the
configuration of the root canal to fill and seal the root canal
from the apex of the root to a desired distance away from the apex,
said single use filler means having an apical end, and an insertion
end, wherein said insertion end includes a threaded filler
connector assembly, and
(b) multiple use inserter means for inserting said filler means
into the root canal and properly positioning said filler means in
the root canal, said multiple use inserter means having a connector
end and a handle end wherein said connector end includes a threaded
inserter connector assembly configured to threadedly and removably
engage the threaded filler connector assembly of said filler
means.
2. The root canal filler assembly of claim 1, wherein said filler
means includes a relatively rigid longitudinal core portion and a
relatively flexible plasticizable coating portion extending axially
along said core portion from said apical end to terminate short of
said insertion end to leave said core portion exposed al the
insertion end of said filler means.
3. The root canal filler assembly of claim 2, wherein said filler
connector assembly is positioned on said exposed core portion.
4. The root canal filler assembly of claim 3, wherein said inserter
connector assembly is positioned interiorly of the connector end of
said insertion means.
5. The root canal filler assembly of claim 4, wherein said inserter
connector assembly and said filler connector assembly comprise
correspondingly threaded sections of said inserter means and said
filler means is threadedly engaged by said inserter means.
6. The root canal filler assembly of claim 5, wherein said filler
means core portion is formed of metal.
7. The root canal filler assembly of claim 6, wherein said filler
means coating portion is formed of gutta percha.
8. The root canal filler assembly of claim 5, wherein said filler
means coating portion comprises two layers of differentially
melting plasticizable material, said innermost layer having a
higher melting point than said outermost layer.
9. The root canal filler assembly of claim 8, wherein the innermost
of said two layers comprises high melting gutta percha and the
outmost of said two layers comprises low melting gutta percha.
10. The root canal filler assembly of claim 1, wherein said
inserter means further includes handle means located at the handle
end thereof to facilitate the insertion and manipulation of said
inserter means in a root canal.
11. The root canal filler assembly of claim 10, wherein said
inserter means further includes measuring means for measuring the
distance said filler assembly has been inserted into said root
canal and assessing proper placement of the filler assembly in the
root canal.
12. The root canal filler assembly of claim 11, wherein said
measuring means comprises a stop axially slidable along said
inserter means.
13. A filling device for refilling a tooth root canal with a canal
filling during treatment of the tooth to permit the canal filling
to be easily inserted, positioned, and removed, said filling device
comprising:
an elongate filler cone having first and second ends and comprising
a relatively narrow tip portion formed at said first end, said
elongate filler cone being insertable and adjustable within and
removable from the tooth root canal;
removable elongate insertion means for inserting, adjusting,
repositioning, and removing said elongate filler cone in the root
canal, said removable elongate insertion means comprising first and
second ends and a handle portion formed at said first end, and said
removable elongate insertion means being reusable: and
connection means disposed at said second end of said removable
elongate insertion means for releasably connecting said removable
elongate insertion means to said second end of said elongate filler
cone such that said elongate filler cone can be connected to,
removed from, and reconnected said removable elongate insertion
means as required.
14. A root canal filling device according to claim 13 wherein said
elongate filler cone is formed with external threads on said second
end and wherein said connection means comprises a hollows
internally threaded portion formed at said second end of said
removable elongate insertion means, said elongate filler cone and
said removable elongate insertion means being releasably,
threadably connectable and reconnectable together.
15. A root canal filling device according to claim 14 wherein said
second end of said elongate filler cone comprises a relatively
narrow tip portion receivable in said hollow internally threaded
portion to facilitate connecting said elongate filler cone to said
removable elongate insertion means.
16. A root canal filling device according to claim 13 wherein said
relatively narrow tip portion formed at said first end of said
elongate filler cone is sufficiently rigid to resist binding or
bending back when said elongate filler cone is inserted into a root
canal.
17. A root canal filling device according to claim 13 wherein said
removable elongate insertion means comprises a rigid inserter
shaft.
18. A root canal filling device according to claim 17 wherein said
inserter shaft is formed of metal.
19. A root canal filling device according to claim 17 wherein said
inserter shaft is formed of plastic.
20. A root canal filling device according to claim 17 further
comprising measuring means for indicating the approximate length of
the root canal to thereby reduce the incidence of long or short
placement of said elongate filler cone within the root canal.
21. A root canal filling device according to claim 20 wherein said
measuring means comprise a rubber disk slidably mounted on said
inserter shaft near said first end below said handle.
22. A root canal filling device according to claim 13 wherein said
handle is shaped like a root canal file.
23. A root canal filling device according to claim 13 wherein said
handle is formed of plastic.
24. A root canal filling device according to claim 13 wherein said
handle is formed of rubber.
25. A root canal filling device according to claim 13 wherein said
elongate filler cone comprises an inner core layer and an outer
shell layer.
26. A root canal filling device according to claim 25 wherein said
inner core layer is formed of metal.
27. A root canal filling device according to claim 26 wherein said
inner core layer is formed of manlure.
28. A root canal filling device according to claim wherein said
outer shell layer is formed of a thermoplastic material.
29. A root canal filling device according to claim 28 wherein said
outer shell layer is formed of gutta percha.
30. A root canal filling device according to claim 25 wherein said
elongate filler cone further includes a retentive surface formed on
said inner core layer.
31. A method of filling the root canal of a tooth with a
biocompatible filler after the tooth has been opened to expose the
root canal and the canal has been cleared of diseased or damaged
pulp comprising the steps of:
(a) selecting an appropriately sized obturator means including an
elongated rigid core portion, a flexible plasticizable coating
portion covering said core portion to extend from one end of said
core portion axially along said core portion, and a threaded
connector assembly at the other end of said core portion for
filling and sealing the apical end of the root canal:
(b) temporarily connecting the threaded connector assembly of said
obturator means to a correspondingly threaded connector assembly on
the connector end of an inserter means for inserting said obturator
means into the root canal by screwing said connector assemblies
together to form a tool canal filler assembly: (c) inserting said
root canal filler assembly into the cleared root canal so that the
coating portion of the obturator means is positioned within the
canal to fill and seal the apical end of the root canal:
(d) disconnecting the inserter means from the obturator means by
unscrewing the inserter means threaded connector assembly from the
obturator means threaded connector assembly; (e) removing said
inserter means from the root canal to leave the obturator means in
the root canal, thereby permitting said inserter means to be
reused: and
(f) sealing the portion of the root canal not filled by the
obturator means and restoring the integrity of the tooth.
32. The method of filling a root canal described in claim 31,
further including the steps of removing the seal formed in step
(f), reinserting said inserter means into said root canal, screwing
said threaded connector assembly of said obturator means into said
threaded connector assembly of said inserter means, repositioning
said obturator means, disconnecting said threaded connector
assemblies, and removing said inserter means from said root
canal.
33. The method of filling a root canal described in claim 31,
further including the step of, after step (c) but before step (d),
heating said obturator means to plasticize said plasticizable
coating.
34. The method of filling a root canal described in claim 31,
further including the step of, after step (e). inserting a support
post into said root canal to extend from said obturator means to
the tooth surface.
35. The method of filling a root canal described in claim 31,
further including the step of, after step (c) but before step (d).
using measuring means to measure the distance said assembly extends
to said root canal. .Iadd.
36. A biocompatible filler for insertion into the canal of the root
of a tooth to fill and seal the canal following removal of tooth
pulp and treatment of the canal, said filler comprising:
a relatively rigid longitudinal core; and
a relatively flexible plasticizable coating extending axially along
at least a portion of said core, said plasticizable coating
comprising an innermost layer and an outermost layer of
differentially melting plasticizable material. .Iaddend. .Iadd.37.
The filler of claim 36, wherein the innermost layer has a higher
melting point than the outermost layer..Iaddend. .Iadd.38. The
filler of claim 36, wherein the innermost layer comprises high
melting gutta perch and the outermost layer comprises low melting
gutta percha. .Iaddend. .Iadd.39. The filler of claim 36, wherein
the core is metal..Iaddend. .Iadd.40. The filler of claim 39,
further comprising a coating of metal plasma on the metal core
underneath
the innermost layer of gutta percha..Iaddend. .Iadd.41. A
relatively flexible, plasticizable biocompatible filler for
insertion into the canal of a root of a tooth to fill and seal the
canal following removal of tooth pulp and treatment of the canal,
said filler comprising:
a first plasticizable material which is essentially solid at room
temperature and which is spreadable in the canal under heat and/or
mechanical action so as to flow therein;
a second plasticizable material which is essentially solid at room
temperature and which is spreadable in the canal under heat and/or
mechanical action so as to flow therein under substantially
different conditions of heat and/or mechanical action as compared
to said first plasticizable material, wherein said first and second
plasticizable materials spread in the canal to fill the canal
during a filling
procedure, one spreading prior to the other..Iaddend. .Iadd.42. The
material of claim 41, wherein said first plasticizable material and
said second plasticizable material have substantially different
melting points..Iaddend. .Iadd.43. The filler of claim 41, wherein
said first plasticizable material comprises a relatively high
melting point gutta percha and said second plasticizable material
comprises a relatively low melting point gutta percha..Iaddend.
.Iadd.44. The filler of claim 41, wherein said first plasticizable
material comprises an inner layer of relatively high melting point
gutta percha and said second plasticizable material comprises an
outer layer of relatively low melting point gutta percha
surrounding the layer of relatively high melting point gutta
percha..Iaddend.
Description
TECHNICAL FIELD
The present invention relates generally to devices and methods for
treating root canals. More particularly, the present invention
relates to a two part root canal treatment device including a
single use portion for filling the apical end of a root canal and a
multiple use portion of which temporarily engages the single use
portion to insert it into the root canal and is then removed.
BACKGROUND OF THE INVENTION
A tooth is a calcified structure that includes a crown portion
connected to one or more relatively long root portions which extend
through the gum and into the jawbone. The roots of a tooth usually
curve slightly as they extend away from the tooth crown to
culminate in a relatively thin apex. Each tooth root includes a
root canal with rough-surfaced inner walls. In a healthy tooth, the
pulp chamber and root canal are filled with pulp, which includes
the tooth blood supply and nerve. Dental problems which involve the
tooth roots, particularly the root canals, are quite common.
When a tooth becomes diseased or damaged as a result of infection,
abscess formation, periodontal disease; trauma to the tooth or a
deep cavity, removal of the tooth's pulp may be the only way to
save the tooth. The damaged or diseased pulp, which contains the
nerves and blood supply for the tooth, can cause additional damage
or infect surrounding tissues unless the tooth is treated to remove
the affected pulp. Treatment of the tooth involves making an
opening in the the crown of the tooth to allow access to the pulp
in the tooth pulp chamber and root. The pulp is removed, and the
canal and pulp chamber cleaned thoroughly and medicated, if
required, to prevent further infection. Once all infection is gone,
the root canal and pulp chamber are filled and sealed, and the
crown of the tooth is restored. The extent of the crown restoration
necessary may vary from a simple "filing" if the tooth is
structurally sound to a full crown replacement supported by one or
more posts placed in the root canal.
The root canal treatment preferred by endodontists involves filling
the root canal and pulp chamber with an inert biocompatible
material to prevent further complications. Unless the pulp is
removed and the root canal refilled with a biocompatible, inert
material, the damaged pulp could serve as a medium for bacteria or
act as a "foreign body," and the root could become further inflamed
or infected. It is especially important to insure that the root
apex is sealed and filled properly to prevent the intrusion of
fluids from the tissue surrounding the root into the canal, or to
prevent the extrusion of filler material into this tissue.
When problems with the tooth root and the root canal arise, there
may be damage to the crown of the tooth as well. Crown damage could
also occur during drilling of the tooth to treat the root canal if
the structural integrity of the tooth has been affected by the
disease, trauma or infection that originally caused the root canal
problem. To restore the crown may require the placement of one or
more posts within the tooth that extend into the root canal, to
anchor a crown or other restorative work. Such posts are used not
only to assist in the total restoration and rehabilitation of the
tooth. but are sometimes placed in the root canal as an additional
tooth support, even when crown restoration is not required. Posts
that are located in the root canal are typically cemented in place
after the pulp is removed before the root canal is filled.
Consequently, their removal can be difficult.
In some cases, additional treatment or restorative work must be
performed on the tooth some time after the root canal has been
filled and sealed. This may require the removal of the root canal
filling to allow the necessary treatment or restoration of the
tooth. Until now, root canal fillings could only be removed with
considerable manipulation of the root canal and tooth. These
procedures and the use of potentially toxic substances, such as
chloroform, increase the attendant risk of damage to surrounding
tissues resulting from available root canal treatments.
Various and diverse devices and methods have been used to fill and
repair root canals. Filler points or cones made from gutta percha
or silver, posts screwed into the jawbone, and obturators, such as
those marketed under the name THERMAFIL by Tulsa Dental Products,
have been used to fill the apical portion of the root canal. Pastes
and injectable gutta percha have been used both in conjunction with
the above devices and separately to fill root canals. However, all
of these devices and methods have inherent disadvantages. are
biocompatible, pure gutta percha points are overly flexible and
lack rigidity, which causes them to bind in the root canal during
insertion. Consequently, a gutta percha point often cannot be
inserted as far into the root canal as it should go. In addition,
it is possible to insert such a point farther into the root canal
than is desirable. If this occurs, a pure gutta percha point is
extremely difficult to retrieve and remove. Other available pliable
biocompatible materials, such as injectable gutta percha and
pastes, are difficult to control at the root apex and may be forced
through the root apex. In addition, the injectable pastes sometimes
tend to resorb.
Kinsman U.S. Pat. No. 674,419 and Miller U.S. Pat. No. 1,463,963
are representative of early solutions to the problem of filling a
root canal. These patents disclose the use of gutta percha points
having metallic cores for this purpose. Although these fillers have
more rigidity and may be somewhat easier to control than pure gutta
percha points, the metallic core points described in these patents
are difficult to retrieve if pushed too far into the root canal. If
the canal requires retreatment at a later date, moreover, this type
of gutta percha metal point is very difficult to remove.
Some rigid metallic fillers, for example silver points, tend to
corrode over time, as they are not highly biocompatible with root
canal environment. These elongated point devices, moreover, are not
flexible and cannot adequately conform to the curvature of the
tooth root canal to fill and seal the canal effectively. Also, it
may be difficult to place a post in the same canal with a silver
point or cone. If the pulp is replaced with a silver point which
extends substantially the entire length of the canal, the incisal
or occlusal end of the point must be removed to accommodate a post.
Removal is usually accomplished by drilling. However, not only is
it difficult to drill through the silver, but such drilling
vibrates the silver point so that damage to the apical seal is
extremely likely. Consequently. It is necessary to notch the silver
point prior to insertion in the canal so that the top of the point
may be broken off with dental pliers rather than drilled. Finally,
the retrieval and removal of these points for subsequent treatment
of the tooth is not easily accomplished.
One recently proposed root canal filler device is a one piece
endodontic obturator which includes a calibrated stainless steel
carrier shaped like a standard endodontic file and coated on one
end with alpha gutta percha. This carrier is provided in a range of
different sizes corresponding to standard endodontic file sizes. A
handle on one end of the carrier assists the dentist in the
insertion of this obturator into the root canal. An endodontic file
must first be inserted in the root canal to obtain the approximate
distance the obturator must be inserted into the root canal. Once
this distance is determined. A rubber stop on the carrier is
positioned at the calibration on the carrier corresponding to this
distance. The gutta percha portion of the obturator is then heated
until it begins to expand and becomes plasticized, and the
obturator is inserted into the root canal to the level indicated by
the rubber stop. The stainless steel carrier provided with this
device is significantly longer than required to fill the root
canal. Consequently, the excess carrier shaft must be cut off and
removed. This is done with a fissure but in a high speed hand piece
while the shaft is in the root canal. The excess shaft, handle and
stop are then removed to allow vertical condensation of the gutta
percha.
While the aforementioned endodontic obturator represents an
improvement over previously available root canal filler devices, it
still suffers from some significant disadvantages. Because the
gutta percha tip is heated prior to insertion into the root canal.
it is possible to push the end of the stainless steel carrier shaft
through the warmed gutta percha during insertion so that exposed
metal rather than plastic gutta percha contacts the root apex. If
too much force is exerted during insertion. not only could the
metal be exposed, but the metal shaft could actually penetrate the
root canal apex. In neither instance would an effective apical root
canal seal be formed Severing the carrier shaft to the proper
length with a fissure bur in a high speed hand piece after the
obturator has been inserted into the root canal subjects the
obturator to undesirable high speed vibrations that could vibrate
the device loose and also traumatize the tooth. Cutting this
carrier shaft inside the mouth is also more difficult for the
dentist. In addition, this prior art endodontic obturator requires
special treatment so that the root canal can accommodate both the
obturator and a post, if one is required for restorative work. The
stainless steel carrier shaft must be properly notched somewhat
below the level of he rubber stop and handle prior to insertion and
the shah broken off after insertion. Too large a notch will weaken
the shaft so that it could break during insertion. while too small
a notch may prevent breakage of the shaft at the proper time.
Moreover, the removal of this obturator from the root canal can
only be accomplished with difficulty. If the obturator is notched
and separated well down into the root canal, its removal is
virtually impossible. The handle portion of the obturator is
permanently removed when the carrier shaft is severed, and,
therefore, cannot be reconnected to the shaft. As a result, removal
of the obturator requires the application of heat or solvents to
the gutta percha and instruments to the carrier shaft to extract
them from the root canal. Consequently, subsequent treatment a tool
canal into which such an obturator for has been inserted can be
performed only after a series of steps potentially traumatizing to
the root canal, tooth and surrounding tissue.
Finally, if the aforementioned obturator is inadvertently thrust
past the apical foramen, it is almost impossible to pull the metal
core back into the root canal without leaving the already
plasticized gutta percha behind.
Another prior art root canal filler is described in Tosti U.S. Pat.
No. 3,813,779 discloses a threaded post which is screwed through
the tooth and into the jawbone to fill the root canal and anchor
the tooth. Apart from the likelihood of unnecessary trauma to the
tooth and severe complication should the procedure not be properly
performed, this device is not likely to provide an effective root
canal seal.
The prior art devices for filling root canals, therefore. suffer
from numerous drawbacks. Often, these devices are too flexible so
that positioning and repositioning them is difficult. More rigid
devices are unable to adequately fill and seal the apical region of
the root canal as they can not conform to the curvature of the
tooth root. Many of the devices are inserted, positioned, or
customized within the root canals in ways that unduly traumatize
the tooth, gums, jawbone, and surrounding mouth areas. Moreover, if
these devices are improperly manipulated, further trauma and
complications could result. Available tools used to insert
available root canal filler pins or points are not easy to use.
None of the known devices and tools for filling root canals,
moreover, is easy to use, permits the filler to be first attached
and subsequently reattached to an inserter tool for adjustment or
removal of the filler, or employs a reusable inserter.
Thus, the prior art fails to provide a root canal filler device
including a single use substantially flexible filling cone or
obturator that conforms to both the relatively long length and the
curvature of a tooth root canal to effectively seal and fill the
root canal and that can be adjusted to the proper length after
radiographic confirmation of placement within the root canal,
wherein the obturator is removably reattachable to a multiple use
inserter tool whereby the obturator is inserted into a root canal
so thai after the inserter tool has been separated from the
obturator, the inserter can be easily reattached to the obturator
to reposition or remove it, as required. There is a need,
therefore, for such a two part root canal filler device including a
single use obturator for effectively filling and sealing the root
canal and a multiple use insertion tool for inserting and removing
the obturator as required for the treatment and ongoing management
of root canal problems.
SUMMARY OF THE INVENTION
It is an object of the present invention, therefore, to provide a
two part root canal filler device that includes a single use filler
portion removably reattachable to a multiple use inserter portion
which facilitates both the initial filling and sealing of a root
canal and the ongoing management of root canal treatment.
It is another object of the present invention to provide a root
canal filling device that includes a filler portion that can be cut
to the specific length required to fill and seal the root canal at
a location outside the mouth.
It is another object of the present invention to provide a root
canal filling device that includes a filler portion that will
effectively seal the root canal without corroding or irritating the
surrounding tissue.
It is another object of the present invention to provide a two part
root canal filling device that includes an single use filler
portion including a relatively flexible coating formed of a pliable
biocompatible material which substantially conforms to the shape of
the root canal when inserted therein and a relatively rigid core
formed of a biocompatible metal which is releasably engaged by a
multiple use inserter tool which guides the filler portion to its
proper position in the root canal.
It is another object of the present invention to provide a root
canal filling device that includes a single use, elongate, cone
shaped filler portion that produces a consistent, effective apical
seal, allows for easy placement and adjustment during obturation of
the root canal, and is easily retrieved if the root canal requires
retreating.
It is another object of the present invention to provide a root
canal filling device which both effectively seals and fills a root
canal and accommodates a dental post in the canal.
It is a further object of the present invention to provide a method
of filling a root canal wherein a single use root canal filler
formed of a biocompatible flexible coating and a biocompatible
rigid core is inserted into the canal of a tooth root by a
temporarily attached multiple use inserter tool to seal and fill
the root canal along a desired distance from the apex, and the
inserter tool is easily and nontraumatically removed from the
canal.
It is yet a further object of the present invention to provide a
method of filling a root canal wherein the canal is quickly and
effectively sealed and filled to the proper level in a manner which
minimizes trauma to the tooth and mouth tissues.
It is a still further object of the present invention to provide a
treatment method for tooth root canals whereby a single root canal
can be effectively filled and sealed during a first treatment and
the filler easily removed and the canal retreated during one or
more subsequent treatments.
The aforesaid objects are achieved by providing a two part root
canal filler assembly that includes a single use obturator which is
sufficiently flexible and plastic to be inserted into the root
canal to conform to the shape of the canal so that it seals the
apex and fills the canal to a predetermined distance from the apex.
A multiple use inserter tool which temporarily and removably
engages the obturator is provided to assist the endodontist in
inserting one or more such obturators into the root canal and
positioning the obturator or obturators properly within the canal
to fill the canal as required. The inserter tool is then easily
disengaged from the obturator and removed from the root canal with
substantially no trauma to the canal or surrounding structures. The
obturator includes an elongated metal core which is coated with a
flexible plasticizable material along its apical end. A portion of
the core extends beyond the coating to form an uncoated obturator
shaft, which includes a connector assembly and terminates in a
point at its insertion end. The inserter tool is an elongated rod,
one end of which is a connector end with a connector assembly which
engages the corresponding connector assembly on the insertion end
of the obturator shaft. The opposite end of the inserter tool
includes a handle having substantially the same configuration as a
conventional root canal file and a measuring means for ascertaining
the distance the inserter tool has been inserted into the
canal.
The present invention additionally provides a method for filling
and sealing a tooth root canal using the above-described assembly,
wherein the obturator threaded shaft is screwed into the threaded
recess in the inserter tool to temporarily connect it to the
inserter tool, and this assembly is inserted into the canal of the
root of a tooth so that the coated apical end of the obturator
seals and fills the apex of the root canal to the required
distance. Heat is applied to the plasticizable coating to cause it
to become plastic and conform to the irregular surfaces of the root
canal, thus insuring that the canal is completely filled and
sealed. The inserter tool is then disconnected from the obturator
threaded shaft and removed from the canal. If removal of the
obturator is subsequently required, the inserter tool is simply
reinserted into the canal and reconnected to the obturator so that
the connector assemblies are teengaged. Because repeated removal of
the obturator can be accomplished readily and easily, any cutting
required to shorten the obturator can be done outside the dental
patient's mouth.
Various additional advantages and Features of novelty which
characterize the invention are further pointed out in the claims
that Follow. However, for a better understanding of the invention
and it advantages, reference should be made to the accompanying
drawings and descriptive matter which illustrate and describe
preferred embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cut away side perspective view of the root canal filler
assembly of the present invention inserted in the root canal of a
tooth, wherein the assembly components are temporarily
connected.
FIG. 2 is a cut away side perspective view of the root canal
assembly of the present invention wherein the assembly components
have been disconnected.
FIG. 3 is a partially cut away side view of the connector
structures of the two part root canal filler assembly of the
present invention;
FIG. 4 is a partially cut away side view of another embodiment of
the two part root canal filler assembly of the present
invention;
FIGS. 5a-5d illustrate the root canal filling method of the present
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The root canal filler assembly of the present invention provides
the endodontic specialist with a treatment device and method for
easily and effectively performing the initial treatment and
managing the ongoing care of problems associated with the roots of
the teeth. In the past, the treatment and care of these problems
has been neither easy nor always as effective as could be desired.
Until the present invention, once a root canal filler was inserted
into the canal it could be retrieved only with difficulty, which
usually resulted in some degree of trauma to the tooth and
surrounding structures in the dental patient's mouth. The present
invention offers an alternative to previously available root canal
devices and filling procedures that is not only nontraumatic and,
therefore, more easily tolerated by the dental patient, but is also
extremely effective and reliable in filling and sealing the root
canal.
Referring to the drawings, the root canal filler assembly of the
present invention is shown n in FIGS. 1 and 2 inserted in the root
canal of tooth 10. Although the tooth shown is a lower tooth, the
assembly is equally effective in filling the roots of upper teeth.
The tooth shown in FIGS. 1 and 2 has had much of the crown removed
to provide access to the pulp chamber 12 and root canal 14. The
pulp, including the blood supply and tooth nerve has already been
removed from the root canal as part of the treatment of the tooth
shown in FIGS. 1 and 2, so that the canal is substantially cleared
of this tissue. FIGS. 1 and 2 show a perspective side view of the
tooth 10 with a portion of the tooth removed to illustrate clearly
the placement of the present root canal filler assembly 16 in the
canal 14.
Although the walls 18 of root canal 14 are shown as being
relatively straight and smooth, in actuality the canal may curve
somewhat, and the walls have a rough irregular surface. These
features have presented obstacles to the proper filling and sealing
of root canals which the present invention has overcome.
The root canal filler assembly 16 is illustrated in FIG. 1 as it
would appear following the initial insertion of obturator 20, the
filler portion of the assembly, into the apex 15 of the root canal
14. The obturator 20 is shown temporarily connected to the inserter
portion, inserter tool 22. The obturator 20 has an apical end 24,
which contacts the apex 15 of the root canal, and an inserter end
26, which will be described in more detail below in connection with
FIG. 3. The inserter tool has a connector end which engages the
insertion end 26 of the obturator 20 at joint 27 within the root
canal. The opposite end 30 of the inserter tool 22 extends beyond
the pulp chamber 12 to support a handle 32.
Although other handle configurations could be employed, the three
part substantially cylindrical arrangement shown in FIGS. 1 and 2
is preferred. This configuration is substantially identical to that
of a conventional root canal file and, as a result, provides the
dentist with a familiar structure. The tactile familiarity provided
by this particular handle further enhances the efficiency with
which the assembly can be used to fill and otherwise treat root
canals, which must, of necessity, be performed in very limited
space. The handle may be formed of metal, rubber, or a plastic,
such as polyvinyl chloride (PVC). However, a metal handle would
only be selected if the root canal filler device was intended to be
used with a heat applicator.
The root canal filler assembly also preferably includes a stop 34
slidably mounted on the inserter tool 22 to move axially along the
inserter between the handle 32 and the top of the pulp chamber 12.
Stop 34, which is preferably formed of rubber or a similar
flexible, substantially inert material, is employed as a measuring
gauge to facilitate the assessment of the correct placement of the
obturator 20 at the root canal apex 15. The manner in which stop 34
performs this function will be explained herein below.
Unlike the prior art, the present root canal filler assembly
includes two major components which are temporarily connected prior
to their insertion into the root canal and are then disconnected
within the root canal once obturator 20 has been placed in an
optimum sealing position. FIG. 2 illustrates the components of the
root canal filler assembly 16 after they have been disconnected,
but before the inserter Tool 22 has been removed from the root
canal. Connector end 28 of inserter tool 22 has been removed from
its connection with inserter end 26 of the obturator 20 and is
shown spaced beyond the terminus 36 of obturalor 20. Terminus 36,
which will be discussed in detail in connection with FIG. 3, is
telescopingly received inside the inserter tool 22 when the
obturator 20 is connected to the inserter tool and, thus, is not
visible when these components are connected as shown in FIG. 1.
Once the inserter tool 22 is separated from the obturator 20 as
shown in FIG. 2. the obturator is generally intended to remain
permanently in place in the root canal 14. However, achieving the
proper position of the obturator in the canal may at times be
difficult due, for example, to the curvature of the tooth root or
the angle of access to the root canal. Removal of the obturator
from the root canal and its reinsertion into the root canal are
greatly simplified by the present invention. The inserter tool 22
is simply reconnected to the obturator 20 to form the unitary
structure of FIG. 1, and the handle 32 can be employed to easily
extract the assembly from the canal. Reinsertion into the canal is
likewise readily accomplished. This arrangement is especially well
suited to root canals that previously were extremely difficult to
fill and seal in a manner which achieved an optimum apical
seal.
In addition, the temporary easy disconnect-reconnect feature of the
present root canal filler assembly 16 eliminates the traumatic
separation which accompanies the unitary permanently connected
prior art filler devices.
Filler 3 illustrates in detail the temporary connect-disconnect
feature of the present root canal filler assembly which renders the
inserter tool 22 capable of repeated use. As noted above, the
assembly 16 includes two parts: a multiple use inserter tool 22 and
a single use obturator 20. The inserter tool is designed to be
reused a number of times to insert a member of obturators into one
or more tooth root canals during a single treatment session. The
filling of teeth with multiple root canals may require the
insertion of more than one obturator like obturator 20. In this
case, a single inserter tool 22 can be connected to each obturator
in turn to position it in the root canal and then disconnected and
removed from the canal. The inserter tool 22 can also be cleaned
and sterilized for reuse at a later time.
The inserter tool 22 is an elongated shaft and, as discussed in
connection with FIGS. 1 and 2, includes a handle receiving end 30
and a connector end 28. The inserter tool shaft may be formed of
metal, plastic or any similar sterilizable material having
sufficient rigidity to provide a positive connection with obturator
20 and to insert the obturator into the apex 15 of root canal 14.
An inserter tool having a shaft that is approximately 12 to 15 mm
in length has been found to function most effectively.
The connector end 28 of inserter tool is formed with a recess 38
which is shown partially cut away in FIG. 3. Recess 38 includes one
part of a connector assembly 40 which temporarily, but securely,
engages a corresponding connector assembly 42 on the obturator 20.
Although the preferred type of connector assembly is formed from a
the mating threaded connector assemblies 40 and 42 shown in FIG. 3,
other types of connectors that provide the secure temporary
connection, disconnection and reconnection required by the present
invention could also be employed. The longitudinal extent of recess
38 should be sufficient to accommodate the entire terminus 36 of
obturator 20, including the connector assembly 42.
The obturator 20 has a configuration which generally resembles that
of a conventional hand held root canal file. This allows obturator
20 to be held securely by hand without resort to the cotton pliers
customarily required for the insertion of root canal filler
structures while it is connected to inserter tool 22 prior to
insertion in the mouth. Obturator 20 preferably has a generally
cone-shaped configuration to conform substantially to the size and
shape of the endodontic files common employed to file root canals.
The obturator 20 includes a rigid core 44 which is coated with a
flexible plasticizable coating 46, which is preferably a high
melting (beta) gutta percha. This flexible plasticizable coating
extends a substantial distance along the core 44 from an apex 24 to
terminate just short of the connector assembly 42. The core extends
beyond coating 46 to support connector assembly 42 and terminates
in terminus 36, which preferably has the inverted cone shape shown
in FIG. 3. This shape has been found particular effective in
guiding and engaging the obturator connector assembly 42 into
engagement with inserter tool 22 during reconnection of the
assembly within the root canal. The obturator rigid core 44,
therefore, is covered with the plasticizable coating 46 from its
apical end 48 to the connector assembly 42.
It is preferred to form the rigid core 44 from a biocompatible,
inert material having sufficient rigidity to allow easy insertion
of the obturator into even a very curved root canal. Preferred
materials include metals such as titanium and stainless steel.
Fluting the exterior of the rigid core material can facilitate
condensation of the plasticizable coating as will be discussed
below.
The apical end 48 of core 44 is located close enough to obturator
coating apex 24 to provide sufficient rigidity to insert obturator
20 into the root canal all the way to root canal apex 15 without
obturator apex 24 binding or bending back on itself. The core
apical end 48 does not extend all the ay to the obturator coating
apex and, therefore, is not likely to be pushed through the coating
during insertion of the obturator into the root canal.
Since tooth root canals are not uniform in size, but vary,
obturator 20 is preferably provided in a range of sizes which
approximate the sizes of conventional root canal files.
Additionally, the configuration of the obturator 20 can be custom
sized to fit a root canal by adding different thicknesses of
coating or gutta percha to the rigid core 44. The width and degree
of taper of the obturator can be made to correspond to the width
and degree of taper of the last endodontic file used to file the
root canal.
The condensation techniques with which the root canal filler
assembly 16 will be used will determine whether additional gutta
percha or like plasticizable material will be required to
completely fill the root canal. If regular lateral condensation
techniques are employed, accessory gutta percha cones will be
required. However, if heat is applied to the obturator through the
handle by a heat applicator, additional gutta percha would not be
required. Instead, the heated obturator could be spun clockwise to
condense the warmed gutta percha apically and laterally. For this
to be successful, however, the rigid core 44 must be properly
fluted. Alternatively, a lubricated hollow condenser could be
employed after removal of the handle.
Once a specific size obturator is selected, it is connected to the
inserter tool 22 by inserting the terminus 36 into recess 38 until
the corresponding connectors on the obturator and inserter tool are
engaged. If connector assemblies 40 and 42 are mating threads as
shown in FIG. 3, once the threads of recess 38 contact the threads
of obturator core 44, these structures can simply be screwed
together.
After the obturator 28 is optimally positioned within the root
canal, it is disconnected from inserter tool 22 by unscrewing the
inserter tool to disengage the threads of recess 38 from the
exterior threads of the obturator 20. If obturator 20 subsequently
must be repositioned or removed, it can be easily reconnected to
inserter tool 22 by repeating this process.
The obturator 20, which is substantially cone-shaped to conform to
the shape of the root canal, may also be referred to as a filler
cone. The rigid core 44 is formed of metal, preferably titanium.
Implant grade titanium is used for metallic core 44 because of its
very high biocompatibility and its resistance to corrosion. The use
of such material prevents complications arising from the
inadvertent placement of obturator 20 too far into the root canal
or from the inadvertent exposure of the metal within the root
canal. The plasticizable coating 46 is preferably formed of gutta
percha because it is malleable and can be easily plasticized and
expands to conform to the various nooks, crannies, and
irregularities in the root canal surface. However, any suitable
thermoplastic material which is biocompatible and has the physical
properties required to provide an effective root canal seal and
filler could also be employed.
Disk-shaped stop 34 (FIGS. 1 and 2), as described above, is used as
a measuring device to provide an approximate measurement of the
length of the approximately 18 mm in length. Thus, stop 34 is
positioned on inserter tool 22 approximately 18 mm from the end of
filler assembly 16 as measured from the apex 24 of obturator 20.
When stop 34 approaches the crown of the tooth during insertion of
the assembly, the dentist knows that the apical environment of the
root canal has been reached by the obturator apex 24. This reduces
the incidence of long or short placement of obturator 20 within the
root canal. Alternatively, inserter tool 22 may be provided with
integral numbered or colorcoded markings extending axially from
handle 32 to estimate the length of a root canal.
Although obturator 20 is selected to be as close in size to the
diameter of the root canal as possible, it will never fit exactly.
Moreover, since the root canal walls are not perfectly smooth,
steps must be taken to insure that the plasticizable coating 46
will completely fill the canal. Lateral condensation techniques can
be used to fill all of the irregularities in a root canal.
According to this method, an obturator 20 is inserted into a root
canal. After it is properly placed within the root canal, a
conventional spreader tool (not shown) is inserted into the root
canal and is forced between the wall and the obturator to put
lateral pressure on the plasticizable coating 46 to contort and
mold it into the irregularities of the root canal surface. After
the spreader tool is removed, if the root canal is not filled, a
conventional accessory gulta percha cone may be inserted into the
root canal and the process repeated until the root canal is
completely filled. A conventional plugger tool (not shown) may also
be used vertically to compress excess plasticizable coating 46,
thereby further insuring complete sealing of the root canal and the
root apex.
The present root canal filler assembly is vastly superior to prior
art devices. The obturator 20 is strong enough to be placed in a
root canal without bending back on itself or binding on the walls
of the canal. The removable, reusable inserter tool 22 permits easy
adjustment and correction of the ebturator placement if it is
placed too far or not far enough into the root canal. Additionally,
the obturator 20 can be placed m the canal and subsequently removed
using inserter tool 22 to provide space for a post, if one is
necessary to restore the endodontically treated teeth. Removal and
repositioning of the obturator 20 are simplified by the provision
of the corresponding connector assemblies 40 and 42 on of the
obturator 20 and the inserter tool 22. This arrangement allows the
obturator and inserter tool to be easily connected, separated, and
reconnected as required. The obturator can also be retrieved
relatively easily for subsequent retreatment of the root canal.
The present root canal filler assembly is easily adapted to
accommodate dental posts, if they are required to support crown
restoration following filling and sealing of the root canal. To
accomplish this, the obturator may be made in two specific lengths,
one for use in a root canal without a dental post and one for use
with a dental post. When a root canal is to be filled without a
post, obturator 20 is provided with a plasticizable gutta percha
coating 46 approximately 10 mm in length as measured from obturator
apex 24. Approximately 1/2 mm of gutta percha protrudes pat the
apex 48 of the rigid titanium obturator core 44, and the remaining
91/2 mm of gutta percha extend along titanium core 44 to the
connector assembly 42. The distance between the end of coating 46
and terminus 36 of the obturator core is about 17 mm. Preferably,
substantially the entire 17 mm of the titanium obturator core is
provided with threads or another connector structure.
When the root canal is to have a post inserted after it is filled,
obturator 20 preferably is provided with about 5 mm of
plasticizable coating 46, approximately 1/3 mm of this protrudes
past the core apex 4-8, and the remaining 42/3 mm covers the rigid
core 44. In this instance, preferably approximately 1-3 mm of rigid
(titanium) core 44 extends beyond the coating 4-6. Most of this
length will preferably support the connector assembly 41 and will
terminate in pointed terminus 36. This particular obturator is
specifically sized so that it does not require cutting after
insertion into the root canal to accommodate a post. This
eliminates completely the traumatic notching and twisting of the
obturator to shorten it after it has been inserted into the root
canal required by prior art root canal filling devices.
Obturator 20 is preferably inserted into root canal 14 unheated and
then may be laterally condensed without heating to spread the gutta
percha so that it fills the canal. Alternatively, optimal filling
of the canal may be achieved by using a heating device attached to
inserter tool 22 by a clip or the like to conduct a standard,
controlled amount of heat from the inserter tool through the
obturator along the metal core 44 to soften the gutta percha
coating 46 before condensing the gutta percha with a spreader or
plugger lubricated with alcohol. Heating the gutta percha outer
coating 46 after obturator 20 is inserted into the root canal
eliminates the possibility that the titanium core will be pushed
out of the gutta percha coating or that the gutta percha will
separate from the titanium during insertion of the filler assembly
into the root canal as is likely with prior art devices.
In one alternative embodiment shown in FIG. 4, plasticizable
coating 46, includes two layers of plasticizable material, one of
which has a higher melting point than the other. It is preferred to
form the inner layer 50 of high melting gutta percha and the outer
layer 52 of low melting gutta percha. Ibis facilitates the use of
heating devices instead of or in addition to lateral condensation
techniques to spread the gutta percha to seal and fill the canal
effectively. A heating device, similar to those made by Hygienic
Corporation, can be employed to heat the filler assembly 16. The
low melting gutta percha outer layer 52 will become plastic and
flow to fill all of the root canal wall surface irregularities. P
The high melting gutta percha inner layer will not become plastic
at the same temperature and, therefore, will continue to provide
some rigidity to the apex 24 and to provide a protective layer
around the apical tip 48 of the titanium metal core. Forming the
coating 46 of two layers allows the heating of the coating to a
well controlled predetermined temperature which is sufficiently
high to plasticize outer layer 52 without plasticizing inner layer
52. This arrangement also permits the heating of the filler
assembly prior to insertion in a root canal without the risk of
exposing the metal core which is inherent in prior art filler
devices. The rigid metal core 44 will be protected by the layer 50
of high melting gutta percha and will not be easily pushed through
the high melting gutta percha coating layer 50 to leave an unsealed
exposed section of titanium. The use of differentially melting
outer layer 52 and inner layer 50 permits even an uncontrolled heat
source, such as a Bunsen burner or an alcohol torch to be used to
heat the gutta percha coating. Even such an uncontrolled heat
source is unlikely to plasticize inner layer 50. Heating may also
be combined with lateral condensation techniques to plasticize the
two layer gutta percha coating and assist its condensation so that
the root canal is completely filled and sealed.
In another form of the present invention, a coating of metal plasma
may be sprayed on the metal core 44, thereby roughening and
increasing the core surface area to provide a better retentive
surface for the gutta percha or other plasticizable coating.
Alternatively, the metal may simply be sandblasted to create the
necessary retentire surface roughness.
A root canal can be filled with the assembly of the present
invention using a series of simple steps which are illustrated in
FIGS. 5a-5d. FIG. 5a shows a crossectional side view of a tooth 60
in place in the mouth. The tooth root 62 extends well into the jaw
bone 64. The opposite end of the tooth terminates in a crown 66
covered with a layer of enamel 68. Gum tissue 70 covers the jaw
bone 64 and helps to hold the tooth securely in place. A pulp
chamber 72 is located in the center of the tooth and extends
longitudinally to the root apex 74 to form a root canal 76. If the
pulp becomes damaged as a result of infection, trauma, disease or
the like, it must be removed to prevent further damage to the tooth
and surrounding tissues.
Removal of the pulp is accomplished by drilling through the tooth
crown 66 to reach the pulp chamber 72. The opening formed must be
large enough to provide adequate access to the pulp chamber to
allow complete removal of the damaged or diseased pulp and cleaning
of the pulp chamber and root canal. FIG. 5b illustrates a tooth
which has been drilled to remove a portion of the crown 66 and
expose the pulp chamber 72. The amount of tooth crown removed can
range from a relatively small section to the entire crown,
depending upon the integrity of the tooth. The extent to which the
crown must be removed will determine whether one or more dental
posts will be required to support crown restoration performed
subsequent to the root canal treatment. As discussed above, the
requirement for a post will affect the length filling cone or
obturator selected to fill the canal.
A filler cone or obturator 80 of the appropriate length is selected
and connected to an inserter tool 82 by inserting pointed terminus
of the obturator into the recess in the inserter tool as discussed
above in connection with FIGS. 1 to 3. The obturator 80 is secured
to inserter tool 82. The handle 83 of the inserter tool is then
used to guide the obturator into root canal 76, as shown in FIG.
5b, by first inserting the obturator apex 84 into the canal. As
indicated above, because of the stiffness of the apex 84, it will
not bind or bend back on itself during insertion. As long as
obturator 80 remains connected to inserter tool 82 the obturator
can be positioned, repositioned, adjusted, or removed from root
canal 76 as necessary merely by manipulating the inserter tool.
The assembly is inserted into the root canal so that the desired
length of obturator 80 can be determined, either by positioning a
slidable stop 85 or using calibrations on the inserter tool 82 as
described in connection with FIG. 1. The assembly is then removed
from the dental patients's mouth, and the excess length of
obturator titanium core (not shown) is cut off, preferably using a
Joe Dondy disc or similar tool. Ideally, after cutting, the
obturator core extends approximately 2 to 3 mm above the gutta
percha coating into the tooth pulp chamber when the apex 84 of the
obturator 80 is properly placed in the root canal apex 74, as shown
in FIG. 5c. This eliminates the possibility of vibrating and
shaking loose the obturator as may occur if a bur is used to cut
the obturator after placement in the root canal. Additionally, it
is much easier to cut the obturator outside the mouth rather than
after the obturator is inserted into the pulp chamber of the root
canal where the cutting can become very messy.
Once the obturator 80 is properly positioned in the root canal as
shown in FIG. 5c. the obturator plasticizable coating may be heated
to a predetermined temperature to plasticize it so that it expands
to fill and seal the root canal. Heating may be accomplished using
any of various heating devices adapted to heat the coating in the
root canal. Lateral or vertical condensation techniques may also be
used, either in addition to or instead of heating. These techniques
involve inserting a spreader or plugger into the root canal to
force the gutta percha or other plasticizable coating into all of
the surface areas of the root canal.
After obturator 80 is properly positioned in root canal 76, as
shown in FIG. 5c, inserter tool 82 is separated from the obturator
by disconnecting the respective connector assemblies on the
inserter tool and the obturator. If a single obturator 80 is
inserted and condensed and does not fill the root canal to the
desired extent, additional obturators may be connected to the
inserter tool and then inserted and condensed as necessary until
the root canal is filled.
Once the root canal is filled to the necessary level, the inserter
tool 82 can be removed simply by disconnecting it from the
obturator and pulling it out of the root canal. If it is necessary
to reposition obturator 80 after inserter tool 82 has been removed,
the inserter tool 82 12 is easily reinserted into the root canal to
engage obturator 80. The preferred obturator and inserter tool
configuration shown in FIG. 3 facilitates the engagement of these
components. The two components are then reconnected, and the
appropriate adjustment performed.
After obturator 80 is located in its final, desired position, the
root canal 76 must be sealed and the tooth crown restored with a
restoration 88 as shown in FIG. 5d. A small removable brightly
colored "cap" of plastic or gutta percha can be made to place over
and cover the threads of the connector assembly 42 placement of the
obturator to prevent cement or other restoration materials from
blocking access to the threads if it became necessary to re-attach
the inserter tool at some future time.
Restoration of the crown will, of course, depend on the extent to
which the crown was removed lo provide access to the root
canal.
If a post is required to support crown restoration, the post can be
inserted after one or more obturators have been placed as required
to fill the apical portion of root canal. If a post is to be
inserted into the root canal at a later time, the gutta percha
sealant 86 can be seared off down to the level of the obturator
80.
Numerous characteristics, advantages, and embodiments of the
invention have been described in detail in the foregoing
description with reference to the accompanying drawings. However,
the disclosure is illustrative only and the invention is not
limited to the precise illustrated embodiments. Various changes and
modifications may be effected therein by one skilled in the art
without departing from the scope or spirit of the invention.
INDUSTRIAL APPLICABILITY
The root canal filler assembly of the present invention is a
substantial improvement over known root canal filling devices. The
filler assembly of the present intention will find its primary
application and use in the field of endodontics where it may be
effectively employed in initially treating and in managing the
ongoing treatment of root canals.
* * * * *