Note: Descriptions are shown in the official language in which they were submitted.
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Summary of the Invention
This disclosure is related to the subject matter of
United States Patent No. 4,758,156, issued July 19, 1988, to
William B. Johnson, entitled: "A TOOL FOR USE IN APPLYING
FILLING MATERIAL TO AN ENDODONTICALLY PREPARED ROOT CANAL".
The conventional techniques for performing
endodontic therapy on teeth are time consuming and often do
not adequately ensure that the entire canal system is filled
with the repair material. Experience has shown that it is not
possible to remove all pulpal remnants and contaminants from a
root canal with current preparation techniques. If the said
pulpal remnants and contaminants are thoroughly entombed in
the repair material, the endodontic therapy will be
successful. If said remnants and contaminants are not
thoroughly entombed, there is a high probability of failure of
the endodontic therapy. Complete entombment of the remnants
and contaminants requires complete obduration of the canal
system. Experience has shown failure to completely obdurate
the canal system to be the primary cause of failure in
endodontic therapy.
The present invention provides an appliance for
applying filler material such as gutta-percha or the like to
an endodontically prepared root canal of a tooth, comprising:
an elongated shaft having a distal portion and a proximal
portion and of length such that the distal portion is
positionable in at least substantially the full length of the
root canal, at least the shaft distal portion being of
material having high biological tolerance, and the distal
portion having a spiral groove formed on the exterior surface
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64053-330
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~thereof; filler material formed onto said distal portion, the
spiral groove serving to improve retention of the filler
material and for augering the filler material into a root
canal when the appliance is rotated after insertion into a
root canal said distal portion of said shaft being severable
from said proximal portion, the distal portion remaining in
the root canal and, in conjunction with said filler material,
serving to fill the canal; and a manually manipulatable handle
portion at said shaft proximal portion.
The present invention also provides an appliance for
applying filler material, such as gutta-percha or the like, to
an endodontically prepared root canal of a tooth, comprising:
a shaft first, distal portion of material having high
biological tolerance and of length to extend at least
substantially the full depth of a tooth root canal and having
an external surface adaptable to receive filler material
thereon, the distal portion having a first end and a second
end; a shaft proximal portion forming a handle portion and
having a first end and a second end, the shaft proximal
portion second end having a recess therein, and the shaft
proximal portion having a reduced cross-sectional area
integral portion which is telescopically removably receivable
in said distal portion recess; and filler material formed onto
said shaft distal portion.
The present invention further provides an appliance
for use in applying filler material, such as gutta-percha or
the like, to an endodontically prepared root canal of a tooth,
comprising: a shaft first, distal portion of material having
high biological tolerance and of length to extend at least
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~ substantially the full depth of a tooth root canal and having
an external surface adaptable to receive filler material
thereon and having a first end and a second end; a shaft
proximal portion forming a handle portion and having a first
end and a second end, the shaft distal portion second end and
said shaft proximal portion first end being configured for
mating engagement with each other; a severable bonding
material between said shaft portion's mating surfaces; and
filler material formed onto said shaft distal portion.
The appliance of the present disclosure is in the
form of a rigid carrier member having a proximal portion and a
distal portion with the distal portion coated with gutta-
percha or similar filler material. The carrier member is a
tapered, slender rod. The carrier member may be constructed
of any material which is of sufficient rigidity and non-toxic
when left in the root canal. One material that has been
employed successfully is stainless steel. A highly
biocompatible plastic or metal carrier member also works
successfully.
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In the present dlsclosure the appliance has
characteristlcally a proxlmal end portion and a distal end
portion with the distal end portion being positionable
into the full length of a root canal and a handle portion
extending above the tooth crown. The distal and proximal
portions of the appliance are constructed so that after
the distal portion is fully seated in the root canal the
portions can be separated from each other.
In one embodiment the appliance has a telescopic fit
between the distal and the proximal portion. In another
embodiment the appliance has the distal and proximal
portions secured to each other by bonding cement. In a
still different embodiment, the distal and proximal
portions are separated by an area of reduced cross-
sectional dimensions 80 that it can be broken off by
moving the proximal portion back and forth relative to the
distal portion to break the tool In the area of weakness.
In another embodiment the distal and proximal
portions do not have a defined point of severance and the
dentist severs the tool after the distal portion has been
fully seated in a root canal.
A further improvement of the appllance of this
invention is the provision wherein the cross-sectional
coniiguration of the appliance in at least the distal
portlon is non-circular, such as triangular, square, oval
or the like. In still a different preferred embodiment
the distal portion has a spiral groove therein to assist
in retention of the filler material on the surface thereof
and in compaction of the flller material within the root
canal. Another embodiment includes the use of a surface
formed by integral pro~ections which serve to retain the
filler material on the distal portion.
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A disc-shaped washer is incorporated on the shaft of
the carrler member and ser~es to act as a stopping plug at
the coronal opening of the canal and thus to pre~ent
viscous flow of the gutta-percha out of the ssid canal
during the insertion pr-ocess. The disc-shaped washer is
also used for distance ~easurement.
The filler material is molded to the carrier member
in a tapered or conically-shsped msnner so a8 to
facilitate the introduction into the typical cansl taper
with sufficient msterisl to ensure complete filling of the
ssid canal and thereby complete obduration of the canal.
The devices may be manufactured in a variety of sizes
to correspond to standard endodontic files.
In using the appliance of this in~ention the root
csnal is first prepsred in the stsndsrd manner by
broaching with endodontic files. An appliance of proper
size is prepared with filler material which then msy be
heated over a flame so thst the filler msterial become~
thermoplssticized. The heated applisnce i8 then inserted
into the root canal with firm spical force. The proximsl
of the sppliance is then separsted from the distsl portion
to lesve the distal portion with the filler msterisl
thereon in the root csnal.
- The proximal portion is then removed while holding
the stopping plug or washer sgainst the tooth snd the
remsinder of the endodontic therapy is completed using
conventional procedures.
In snother arrangement of the appliance, the shaft
may be without a defined means of severing the proximsl
portion from the distsl portion. In this srrsngement the
distal portion with filler msterial thereon i8 inserted in
the root canal to the full depth. The dentist then using
a rotating burr or cutter pliers sever~ the proximal
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portion from the distal portlon; or the dentist may form a
point of weakness by forming a notch in the shaft with a
rotating burr or cutting pliers and then finish separating
the distal portion from the proximal portion by bending
the shaft back and forth at the point of weakness. In
this manner, the appliance can be used in any depth of
root canal without consideration of matching the length Or
the distal portion to the depth of the root canal.
One of the advantages of leaving the distal portion
of the carrier in the tooth, according to the principals
of this invention, is that it greatly reduces the volume
of filler material employed and therefor the effect of
shrinkage of the filler material.
~ or more information as to background material
relating to the present invention, reference msy be had to
pages 184 through 188 of the Journal of Endodontics,
Yolume 4, No. 6, June 1978 which describes a new gutta-
percha technique in which the gutta-percha is formed
around an endodontic file.
A better understanding of the invention will be had
by reference to the following description and claims,
taken in con~unction with the attached drawings.
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DESCRIPTION O~ THE DRAWINGS
~ igure 1 is an enlarged elevational view of the
appliance or carrier member of the present invention. The
appliance includes a slidable stopper or washer which is
shown in cross-section.
Pigure 2 is an elevational view as in ~igure
showing the lower portion of the appliance as encapsulated
in a conically-shaped quantity of filler material such as
gutta-percha. As shown in ~igure 2, the apparatus is
ready for use in filling an endodontically prepared root
canal.
~ igure 3 shows a tooth in cross-section with the root
canal having been endodontically prepared and showing the
appliance of thi~ invention, in reduced scale, as being
employed to apply ~iller material to one of the
endodontically prepared roots.
~ igure 4 is a cross-sectional view of the tooth as in
~igure 3 showing the appliance inserted into the root
canal.
~ igure 5 shows the next step in a sequence ot
applying tiller material to the root canal wherein the
tool ha~ been rotated to sever the proximal portion from
the distal portion.
- ~igure 6 shows the removal of the proximal portion of
the appliance with the distal portion being retained in
the root canal with the filler material.
~ igure 7 is an elevational view of an alternate
embodiment ot the invention in which the applisnce distal
portion is formed with the spiral groove for improved
retention of the filler material. In this embodiment
there is no preselected point ot severance or separation
of the appliance distal portion from the proximal
portion. Instead, the dentist after fully inserting the
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distal portion in 8 root canal severs the proximal portion
using a rotating burr or cutter pliers; or at least forms
a point of weakness 80 tbe proximal portion can be broken
off by moving it back and rorth.
Pigure 8 is an elevational view of the appliance as
in Pigure 7 in which the distal portion is provided with
integral proiections which serve to augment retention of
the filler material.
Pigure 9 is an embodiment of the appliance as in
Pigures 7 and 8 in which the distal portion has a non-
circular cross-sectional configuration.
Pigure 10 is an elevational view of the appliance
showing the arrangement wherein the distal portion is
severable from the proximal portion by a telescopic inner
connection between the two portions and showing filler
material secured on the distal portion.
Pigure 11 is an elevational view as in ~igure 10 and
showing the arrangement wherein the distal portion is
secured to the proximal portion by means of a bondlng
cement.
Pigure 12A is a cross-sectional ~iew of Pigure 9
'showing the arrangement wherein the non-circular
configuration of the distsl portion i~ triangular.
- Pigure 12B i8 a cross-sectional view ot Pigure 9 in
which the distal portion is oval.
Pigure 12C is a cross-sectional view of Pigure 9 in
which the distal portlon is square.
Pigure 13 i8 a cross-sectional view of the distal
portion of the appliance of Pigure 7 to show the spiral
groove in the external surface.
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Detsiled Description of the Preferred Embodiments
Referring to the drawings and ~irst to ~igure 1, the
appliance which is a carrier member is generally indicated
by numeral 10 and is formed of an elongated sha~t 12
having a proximal end 14 and distal end 16. While the
shaft may be of a variety of cross-sectional
configurations, the preferred and simplest shape is that
of a circular cross-sectional configuration so that when
the shaft is positioned in a root canal of 8 tooth, as
will be hereinafter more specifically described, the
flared end portion 18 resists rotation Or the shaft.
Integrally formed on the shaft are a plurality (three
being shown) of spaced apart enlarged cross-sectional
dimensioned portions 20A through 20C. When the shaft i8
circularly cross-sectional as preferred, the enlarged
diameter portion 20A, 20B and 20C are also preferably an
enlarged circular cross-sectional configuration.
Positioned between the enlarged diameter portion 20A,
and the proximal end 14 is a reduced torque resistance
area 22. This is in the form, as shown, of a grooYe
~ormed around the shaft. Between groove 22 and the
proximal end 14 is a sliding stopper or washer 24 having
an opening 24A therein wh}ch slidably receives shaft 12.
- Affixed to the sha~t at the proximal end 14 is a
handle portion 26. Handle 26 is of a diameter larger than
that of a sha~t 12 and may be integral with the shaft or
secured to the shaft and made o~ a material such as
plastic.
~ igure 2 shows the appliance ready ~or use in
inserting a ~iller material into the root canal of an
endodontically prepared tooth. ~igure 2 shows, in cross-
section, filler material 28 formed on the appliance 10.
The filler material 28 may be such as gutta-percha which
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can be formed by hand onto appliance 10. After forming,
the gutta-percha may be warmed in a flame to the proper
stsge.
~ igure 3 shows a tooth 30 having root cansl 32 and 34
therein. A canal 32 has been endodontically prepared in
the standsrd technique such as by the use of files to
remove the root pulp and to prepare, as well as possible,
a clean canal. Appliance 10, with the filler material 28
molded thereon, is ready for use for filling the root
canal 32. The apex of the root canal is indicated at 36
with the tooth crown or coronal portion being indicated by
numeral 38.
~ igures 4 through 6 show the continuation of the step
of filling root canal 32. ~igure 4 shows the appliance
inserted into the canal 32. The filler msterisl 28 is
forced by the insertion of the appliance to fill the canal
to the apical area 36 of the tooth. After full insertion
of the appliance as shown in ~igure 4, rotational torque
is applied to handle 26 severing the shaft at the reduced
torque resistance area 22 as shown in ~igure 5. This is
possible since the flared distal end 18 of the shaft
resists rotation relative to tooth 30.
Atter the shaft has been severed into two portions,
the- proximal portion is withdrawn. The sliding washer 24
is used to retain the filling material 28 in the canal by
holding the washer downwardly as the proximal end portion
of the shaft 12 is withdrawn.
~ igure 6 shows the proximal portion of the appliance
being withdrawn. Washer 24 is then removed leaving the
distal portion of the shaft in place within the root canal
32. The root canal 32 can be more completely filled by
applying additional filler material and by applying
mechanical or hydraulic pressure to the filler material to
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force It into the root canal. The coronal area of the
tooth can be filled in the usual way.
The depiction of the tooth 30 in ~igures 3 through 6
is merely exemplary as teeth are individualistic and the
drawings are intended- to exemplify the steps involved
rather than to accurately pictorially represent the
appearance of the tooth or root canal therein.
The appliance of this disclosure thus provides a
unique and very effective way of conveying filler
material, such as gutta-percha, into an endodontically
prepared root canal. The prior art teaches the use of a
file as a carrier of filler material, however, this known
method, while functioning successfully for its intended
purpose, nevertheless has limitations and problems which
are overcome by the present invention.
~ igure 7 shows an alternate embodiment of the
invention in which the applisnce 10 includes a shaft in
which the proximal portion 40 and distal portion 42 are
integral with each other. The distal portion is tapered
and includes a spiral groove 44. The groove 44 ha~
generally flat outer edges; that is, the groove 44 is for
the purpose of retaining the filler material on the distal
portion. ~urther, the use of the spiral groove 44 has the
adv-antage that after the distal portion with the filler
material thereon is inserted in a root canal and the tool
can be rotated slightly so as to additionally compact and
condense the filler material.
When using the appliance of ~igure 7, the dentist,
after inserting the appliance having filler material
thereon into an endodontically prepared root canal, can,
rather than leave the distal portion in the root canal as
previously discussed, completely remove the appliance.
This technique is accomplished in the following manner.
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~irst, the sppliance distal portion 42 having filler
material thereon, such as shown in Pigures 2 and 3, i8
inserted into the root canal. The dentist then rotates
the appliance, by means of handle portion 26, in the
counterclockwise direction while applging a slight force
in the direction towards the tooth. The distal portion 42
can thus be backed completely out of the root canal,
leaving the filler material therein. As the distal
portion is advanced out of the root cansl the auger action
of spiral groove 44 compacts the filler material in the
root canal.
In another technique the dentist can rotate the
appliance counterclockwise 1/2to a full turn, stop rotation
and apply pressure on the appliance towards the tooth,
rotate again 1/2 to a full turn, stop and apply pressure
towards the tooth, sequentially repeating the steps until
the distal portion 42 is completely removed from the root
canal. This sequence of rotation followed by compaction
utilizes the auger characteristic of the spiral groove 44
to achieve an effective filling of the root canal with
filler material.
The spiral groove 44 in the distal portion 42 is
formed to achieve an auger action and to refrain from
ca w ing a drilling action. That is, the flares are formed
with s~nnetrical outer edges so as not to tend to cut into
the tooth in which the appliance is placed and in which
the tool is rotated for auger purposes.
Thus the embodiment of Pigure 7 can be used in the
technique wherein the applisnce distal portion is left in
the root canal or in which the distal portion is
completely removed. A further advantage of the embodiment
of Pigure 7 is that the provision of spiral groove 44
makes the appliance distal portion more flexible so that
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it will more easily conform to the shape of a non-linear
root canal.
It should be noted that in ~igure 7 the appliance
does not include a severance point. The appliance of
Pigure 7 is exemplary of the use of any of the appliances
which are illustrated herein; which, instead of including
a preselected severance point, are provided without a
severance point. In the use of the appliance in Pigure 7
after the distal portion 42 has been inserted into a
tooth, the dentist can sever the shaft such as by the use
of a high speed burr or by cuttlng pliers. The severance
can be used to merely form a point of weakness and
thereafter the proximal portion separated from the distal
portion by moving the proximal portion back and forward
until it breaks or by the use Or the high speed burr,
cutting plier, or other means to completelg sever the two
portlons. The shaft should be severed below the tooth
coronal area 38 as seen in ~igure 5; that i~, within the
interior confines of the tooth so that when the root canal
and any portion of the coronal area of the tooth which has
been excavated is completely filled, the distal portion 42
remains completely retained within the tooth.
In the method of practicing the arrangement of ~igure
7 wherein no preselected point of separation between the
distal and proximal portions are employed, the steps for
filling an endodontically prepared root canal includes,
first, filler material i8 formed onto the distal end
portion Or the elongated slender shaft formed of material
having high biological tolerance. Next, the shaft having
the filler material thereon is positioned within the root
canal utilizing the handle portion secured to the shaft
proximal portion. The final step is severing the shaft
proximal portion from the distal portion lea~ing the
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2007~20
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distal portion and filler materisl carried thereby in the
root canal The severance of the proximal from the distal
portion can be carried out by operation of severance means
carried by the shaft which severance means can be such as
the circumferential groove or area of weakness 22, as
described with reference to ~igure 1, or another means as
hereinafter described. The step of severing the shaft
proximal portion from the distal portion includes the
application of severance force to the shaft, such as by a
high speed rotary burr or the use of cutting pliers, or
some similar mechanical means.
~ igure 8 shows a still alternate embodiment of the
invention which includes a severance point 22 which is
optional as any of the embodiments can be utilized either
with or without a severance means. The distal portion 42
includes integral burrs 46 extending from the surface to
aid in supporting the filler material on the distal
portion.
Pigure 9 shows the embodiment having the optional
severance point 22 and wherein the distal portion 42 is of
non-circular cross-section configuration.
~ igures 12A, 12B and 12C show examples of such non-
circular cross-sectional configuration. ~igure 12A shows
th~ arrangement wherein the distal portion 42 is of
triangular cross-section; Pigure 12B shows an oval cross-
sectional configuration; and ~igure 12C shows a square
cross-sectional configuration. Such non-circular cross-
sectlonal configurations augment the retention of filler
material onto the distal portlon.
~ igure 10 shows another embodiment of the invention
which includes a defined point of separation. In ~igure
the distal portion 42 has, at the upper end 42A
thereof, a recess 48 therein. The shaft proximal portion
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40 has a reduced external diameter extension portion 50
which is telescopically received within recess 48. In
this manner the distal and proximal portions 42 and 40 are
retained in axial alignment while the tiller material 28
is being secured to the distal portion snd while the
distal portion with filler material thereon is inserted
into the root canal. Thereafter, the proximal portion 40
is easily separable from the distal portion.
~ igure 11 shows a still different means of achieving
separation. In this embodiment the distal upper end 42A
is secured to the proximal end 40A by means of an adhesive
52. The adhesive is sufficient to retain the distal and
proximal portions 42 and 40 in axial alignment while the
filler material 28 is applied and while the distal portion
with attached filler material is inserted into a root
canal, but allow the portion to be separated by bending
the proximal portion relative to the distal portion to
break the adhesive 52.
Thus, ~igures 7-11 show first a variety of means of
improving the retention of the filler material on the
shaft distal portion. Second, they demonstrate two
methods of practicing the invention, one, as in ~igure 7,
wherein no preselected portion of separation is provided
and the dentist perform~ separation after the distal
portion is inserted into the root canal, whereas in
~igures 8-11 various types of arrangements are provided
for a preselected point of separation. The arrangement of
~igure 7 has the advantage that the tool can be designed
wherein the primary consideration is the diameter rather
than the depth of the root canal, whereas in the
arrangements of ~igures 8-11 the tool is preferably
predesigned both to sccommodate the diameter of the root
canal as well as the depth of the root canal. By //s//
reference to accommodation of diarneter root canal means
that the appliance can be manufactured in a variety of
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2007;~Z0
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diameters so that the dentlst can select the maximum
diameter which can be easily accommodated by the
endodontically prepared root canal to thereby require a
reduced amount of filler material wherea~ it can be seen;
however, that only a limited number of diameters are
required since there is no mandatory requirement that the
diameter Or the appliance distal portion closely match the
diameter of the root canal.
While ~igures 7, 8 and 9 show appliances 10 with
filler material formed on the distal portion 42, it is
understood that such appliances may normally be supplied
to dentists with the flller material pre-tormed on the
distal portions as in ~igures 10 and 11.
As previously mentioned herein, the filler material
used for obdurating endodontically prepared root canals
may be such as gutta-percha. Gutta-percha has been the
most com~only used filler material for such purpose since
its introduction over 100 year~ ago. Gutta-percha is
obtained from the latex from sapotaceous trees and is a
trans-isomer o~ polyisoprene and differs ~rom natural
rubber due to its crystalline structure.
Gutta-percha In its material state is in an "alpha"
crystalline form, but when heated above 65~ it becomes
amo~phous and melts. When it cools it returns to a "beta"
crystalline state, unless cooled at a very slow rate.
Thus, it is the "beta" crystalline form which is commonly
used in endodontics. ~urther, commercially prepared
gutta-percha material for endodontics is usually a mixture
of gutta-percha beta crystalline form with a filler, such
as zinc oxide, with other minor ingredients including
heavy metal sulphates, waxes or resins to achieve the
desired characteristics of the end product.
In addition, gutta-percha is sometimes mechanically
treated to change its physical characteristic for use in
endodontics. U.S. Patent No. 4,632,977 teaches a method
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of plasticizing thermoplastic polymers, including gutta-
percha, to change their physical characteristics.
The present invention contemplates the us of filler
materials of any composition or formulation which has
physical and biologicsl tolerance properties adaptable for
use in obdurating root canals. The term "filler material"
as used herein includes gutta-percha in either the slpha
or beta crystalline state, and including compositions
including mixtures of other materials with gutta-percha,
or any other filler material having similar properties for
use in filling endodontically prepared root canals.
The claims and the specification describe the
invention presented and the terms that are employed in the
claims draw their meaning from the use of such terms in
the specification. The same terms employed in the prior
art may be broader in meaning than specifically employed
herein. Whenever there is a question between the broader
definition of such terms used in the prior art and the
more specific use of the terms herein, the more specific
meaning is meant.
While the invention has been described with a certain
degree of particularity it is manifest that many changes
may be made in the details of construction and the
arrangement of components without departing from the
spirit and scope of this disclosure. It is understood
that the invention is not limited to the embodiments set
forth herein for purposes of exemplification, but is to be
limited only by the scope of the attached claim or claims,
including the full range of equivalency to which each
element thereof is entitled.
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