Note: Descriptions are shown in the official language in which they were submitted.
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ENDODONTIC FILE FOR ASSESSING ROOT CANAL DEPTH
Field:
[0001] The
present technology relates to a simple to use and inexpensive endodontic
file or probe for measuring canal depth. More specifically, the technology is
a file that
has a notch or annular groove in the handle to permit use of tool for
measuring the two
most common depths of canals.
Background:
[0002] There
are numerous approaches to measuring the depth of a root canal
including methods that utilize electronic systems.
[0003] For
example, US Publication No. 20090298004 discloses "an electromagnetically
induced cutting mechanism provides accurate cutting operations on soft
tissues. The
electromagnetically induced cutter is adapted to interact with atomized fluid
particles. A
tissue remover comprises an aspiration cannula housing a fluid and energy
guide for
conducting electromagnetically induced cutting forces to the site within a
patient's body
for aspiration of soft tissue. An endodontic probe is used to perform
disinfection ,
procedures on target tissues within root canal passages and tubules. The
endodontic
probe can include an electromagnetic radiation emitting fiber optic tip having
a distal
end and a radiation emitting region disposed proximally of the distal end.
According to
one aspect, the endodontic probe can include a porous structure that
encompasses a
region of the fiber optic tip excluding the radiation emitting region and that
is loaded
with biologically-active particles, cleaning particles, biologically-active
agents, or
cleaning agents for delivery from the porous structure onto the target
tissues. Another
aspect can include provision of the endodontic probe with an adjustable
channel-depth
indicator, which encompasses a region of the fiber optic tip besides the
radiation
emitting region and which is movable in proximal and distal directions along a
surface of
the fiber optic tip to facilitate the provision of depth-of-insertion
information to users of
the endodontic probe."
[0004] At
Paragraph 19 it is stated: 10019] Another feature of the present invention
includes an endodontic probe for performing disinfection of target tissues
within root
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canal passages and tubules, the endodontic probe comprising (a) an
electromagnetic
radiation emitting fiber optic tip having a distal end and a radiation
emitting region
disposed proximally of the distal end and (b) an adjustable channel-depth
indicator
encompassing a region of the fiber optic tip besides the radiation emitting
region. The
adjustable channel-depth indicator can be configured to be movable in proximal
and
distal directions along a surface of the fiber optic tip to provide, for
example, depth-of-
insertion information to a user of the endodontic probe." It is not clear
exactly how this
works, but it is certainly part of a highly complex device and one that would
not be
amenable to being disposable.
[0005] US Publication No. 20070298368 discloses "an instrument for
measuring an
endodontic length, which measures and indicates the distance from a pointed
tip of a
cutting tool to a root apex in order to prevent the pointed tip of the cutting
tool from
going over the root apex when a root canal is perforated by the cutting tool
for an
endodontic treatment of a root canal of a tooth. The endodontic length
measuring
instrument is equipped inside a unit chair system installed in a consultation
room of a
dental clinic and allows a monitor mounted on the unit chair system to display
a
measurement result of the endodontic length, thereby making a medical
treatment of a
root canal easy, easily providing a measurement result of the endodontic
length to a
doctor, and displaying treatment and measurement results of the root canal in
various
and precise ways. The measuring instrument provides a scaled-up image of the
remaining distance from the pointed tip of the cutting tool to the root apex
when the
pointed tip of the cutting tool reaches an area which demands a more precise
measurement result, thereby increasing safety and accuracy in perforation of
the root
canal." This is a highly complex way of determining depth of the canal and
still requires
the use of different probes to determine the depth.
[0006] US Publication No. 20070281275 discloses "a device for use in an
endodontic
root canal, performed using a dental drill hand set has a first upper unit
coupled to the
drill hand set. The first upper unit is cylindrical in shape and has a first
drill shank shaft
therethrough. The upper unit has a first threading on its outside surface. A
second
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bottom unit, cylindrical in shape, is also provided, having a second drill
shank shaft
therethrough. The second bottom unit has a second corresponding threading on
its
inside surface. When the second bottom unit is screwed onto the first upper
unit a root
canal jig is formed having a set height and allowing a shank from the drill
hand set to
pass through the first and second drill shank shafts, such that when the drill
shank of the
drill hand set is drilled into an affected tooth for a root canal, the drill
shank is
prevented from drilling along its entire length into the root of the affected
tooth when
the bottom of the root canal jig contacts the top of the tooth." It does not
describe how
the depth of the canal is measured.
[0007] US Publication No. 20130337401 discloses "an apex-locating method
and device
for determining the depth position of the apex in a dental root canal. It uses
a device
making it possible to form a circuit including a first probe electrode
inserted into the
root canal of a tooth, a second electrode in conductive contact with an oral
mucous
membrane, frequency-generating elements able to produce alternating electrical
signals
at a number of frequencies, and elements for measuring electrical magnitude of
alternating signals in the circuit. Provision is made for exciting the circuit
and measuring
the levels of magnitude of the alternating signals, respectively at low
frequency and at
high frequency and for detecting a point of intersection where the two levels
measured
at low and high frequencies meet and become substantially equal, these
frequencies
being sufficiently far apart for this point of intersection to exist. This
point gives the
position of the apex." This again is a complex method of determining the depth
and not
one amenable to being disposable.
[0008] US Publication No. 20090221931 discloses "a method and system for
detecting
an apical position depending on the change in the impedance between a first
electrode
inserted into the root canal of the tooth of a patient and a second external
electrode
applied to a body surface of the patient. According to some embodiments, a
regulated
current such as an alternating current having a substantially constant
amplitude is
supplied between the two electrodes, and this current serves as a measurement
signal.
Alternatively or additionally, the frequency of the time varying (e.g.
alternating) current
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is at least 50 KHZ, and/or at most about 300 KHZ. In some embodiments, the
presently
disclosed device includes a processing unit which determines a capacitance-
governed
function when the first electrode is in the apical region, and which
determined a
function at least moderately governed by resistance when the electrode is in
the dental
neck region. Optionally, the first electrode inserted into the root canal is a
dental file or
reamer." This again is a complex method of determining the depth and not one
amenable to being disposable.
[0009] US Publication No. 20090148810 discloses "a wireless dental apex
locator (10)
for use in determining the location of the apex of a patient's root, includes
an electronic
module (13) having a battery power source (13a), an impedance analyzer circuit
(13b)
and a radio frequency transmitter (13c); a grounding module (12) having a clip
(15) for
grounding the patient; a probe module (14) having an endodontic probe (21);
and an
associated but not physically connected display unit (11) having a receiver
(31) for
receiving radio frequency signals from the transmitter (13c). The display unit
(11) has an
electronic circuit that conditions the signals and interprets the signal for
display on a
graphic display (31)."
[0010] US Publication No. 20070218420 discloses "an electrically conductive
endodontic instrument coated with a non-conductive layer on a portion of the
instrument wherein a proximal and distal portion of the instrument remain
uncoated
and capable of conducting current therethrough using a traditional apex
locator or other
alerting means. The non-conductive coatings avoid electrical interference from
prior
restorative work and anatomical variants. The coatings may be smooth to
minimize
resistance in the endodontic working space or relatively abrasive to
facilitate filing
where desired. A method for locating the apex of a tooth utilizing an
endodontic
instrument coated with an electrically non-conductive layer wherein a proximal
and
distal portion of the instrument remain uncoated and wherein the instrument is
advanced in a root canal space toward the apex of a tooth. When the distal
portion of
the file makes contact with th,: apex, and a conductive portion of the file is
placed in
electrical contact with an apex locator, or other alerting means, said contact
actuates an
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alert thereby establishing canal depth while the coated portion of the
instrument avoids
electrical artifact from prior restorative work and variant anatomy."
[0011] US Patent No. 6,872,075 discloses the placement of metallic contact
areas on the
surface of the plastic handle of the endodontic tool and extending to the
shaft of the
file. The design is disclosed as a means to improve the accessibility for the
clip of the
apex locator, by providing an attachment point above the tooth. It is also
disclosed as a
means to allow the use of insulating sheaths over the metal shafts to prevent
short
circuits when operating through metal restorations. However, as the contact
area is on
the surface, it unfortunately, is subject to the same deficiency. In addition,
there is a
potential for false readings as any contact with the patient's mouth (tongue,
side of
mouth, lip, etc.) will produce a reading.
[0012] Far more simple approaches include using a moveable washer on the
file. As
disclosed in US Patent No. 7,300,281 " It is also well known that the desired
working
length of each file is established by means of a depth stopper 22, usually in
the form of a
resilient rubber washer, mounted frictionally on the file for adjustment along
the length
thereof to the desired position as determined from radiographs of the tooth.
As
indicated hereinbefore, adjustment of the working lengths of files
conventionally is
accomplished by the use of a ruler and manually adjusting the depth stopper
along the
length of each file, with the final series of files being shortened
progressively by one
millimeter increments."
[0013] A more complex measurement system is disclosed in US Patent No.
4,182,040
where it is disclosed "endodontic files extend freely through openings in a
gauge plate
supported through a central threaded opening by an elongated, rotatable screw
extending upwardly from a base. A post extends upwardly from the base and
slidably
engages the gauge plate to prevent rotation of the plate while allowing it to
move
vertically relative to the base upon rotation of the screw, whereby to afford
adjustment
of the vertical distance between the base and gauge plate to correspond with
the depth
of radicular pulp to be removed from the root canal of a tooth. Depth stoppers
on the
files are adjusted along the length of the files to bring them into abutment
with the
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upper surface of the gauge plate, thereby establishing the depth to which the
files are to
penetrate the root canal. A cover fits removably over the gauge plate and base
to retain
the files on the gauge plate during transport and to accommodate autoclaving
and
sterile storage."
[0014] The most commonly used approach to measuring the depth of a root
canal
involves using a set of files, each being of different lengths (typical file
lengths are
21mm, 25mm, 31mm), in conjunction with an apex locator. The clip of the apex
locator
is placed on the shaft, between the handle of the file and a washer. The
practitioner
then probes the root canal, moving the washer towards the handle while doing
so. The
apex locator makes an electrical connection with the metal shaft of the file
and indicates
when the apex of the root canal has been reached. The practitioner then
manually
measures the distance from the distal end of the file to the underside of the
washer. As
the practitioner does not know the depth of the canal, this procedure usually
requires
the practitioner to use multiple files to probe the canal until the correct
length is
determined. This is because each file has a limited measurement range, further
constrained by the space on the shaft taken up by the clip of the apex
locator. What is
needed is a simple to use, inexpensive file that allows the practitioner to
accurately
probe with a single file, rather than two or more files and on that basis,
determine the
depth.
Summary:
[0015] The present technology provides a simple to use, inexpensive
endodontic file
that allows the practitioner to probe with one file, and on that basis,
determine the
depth to be anywhere between 17 mm to about 31 mm. The technology removes the
need for multiple files that are frequently used in patients. Most patients
have root
canal depths between 17 and 31 mm, and the current prior art files are 21mm,
25mm,
or 31mm ¨ each providing a range of only about 7 mm as compared to the 14 mm
offered by the present technology.
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[0016] In one embodiment an endodontic file having an extended measurement
range
of 14 mm is provided. The endodontic file comprises a shank, a washer and a
handle,
the shank having a proximal end, a distal end, a proximal region and a fluted
region, the
washer slidably located about the proximal region of the shank, wherein the
improvement comprises an exposed shank in an annular groove in the handle, the
exposed shank and the annular groove being about 1 to about 2 mm wide, such
that in
use, the exposed shank provides a user an extended depth measuring capability.
A
method of measuring a root canal depth is also provided.
[0017] In the endodontic file, the annular groove may comprise a pair of
sidewalls that
are substantially normal to the exposed shank.
[0018] In the endodontic file, the extended depth measuring capability may
be 14 mm.
[0019] In the endodontic file, the exposed shank may be about 2 mm wide.
[0020] In the endodontic file, the annular groove may be a notch.
[0021] In the endodontic file, the annular groove may extend around a
circumference of
the handle.
[0022] In the endodontic file, the shank may be 25 mm long from the
proximal end to
the distal end.
[0023] In the endodontic file the shank may be 21 mm long from the proximal
end to
the distal end.
[0024] In another embodiment, an endodontic file having an extended
measurement
range of 14 mm is provided, the endodontic file comprising a shank, a washer
and a
handle, the shank comprising a proximal end, distal end, a proximal region and
a fluted
region and being 21 or 25 mm long from the proximal end to the distal end, the
washer
slidably located in the proximal region, and the handle comprising a exposed
shank in an
annular groove, thereby providing the extended measurement range of 14 mm.
[0025] In the endodontic file, the extended measurement range may provide a
depth
measuring capability of both a 25 mm endodontic file and a 31 mm endodontic
file or
both a 21 mm endodontic file and a 25 mm endodontic file.
[0026] In the endodontic file, the annular groove may be a notch.
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[0027] In the endodontic file, the annular groove may extend around a
circumference of
the handle.
[0028] In another embodiment, a method of measuring a root canal depth with
an
endodontic file is provided, wherein the endodontic file comprises a shank, a
washer
and a handle, the shank having a proximal end, a distal end, a proximal region
and a
fluted region, the washer slidably located about the proximal region of the
shank and
the handle comprises an exposed shank in an annular groove, the annular groove
being
between 1 and 2 mm wide.
[0029] In the method, the annular groove may be a notch.
[0030] In the method, the annular groove may extend around a circumference
of the
handle.
[0031] In the method, the annular groove may comprise a pair of sidewalls
that are
substantially normal to the exposed shaft.
[0032] In the method, the root canal may have a depth between about 13mm
and 27
mm or 17 mm and 31 mm and the endodontic file may provide a depth measuring
range
of 14 mm.
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Figures:
[0034] Figure 1 is a prior art endodontic tool.
[0035] Figure 2 is a medial longitudinal view of the handle of the
endodontic tool of the
present technology.
[0036] Figure 3 is a side view of another embodiment of the endodontic tool
of the
present technology.
[0037] Figure 4 is a longitudinal sectional view through a tooth showing
the endodontic
tool of the technology of Figure 3.
Description:
[0038] Except as otherwise expressly provided, the following rules of
interpretation
apply to this specification (written description, claims and drawings): (a)
all words used
herein shall be construed to be of such gender or number (singular or plural)
as the
circumstances require; (b) the singular terms "a", "an", and "the", as used in
the
specification and the appended claims include plural references unless the
context
clearly dictates otherwise; (c) the antecedent term "about" applied to a
recited range or
value denotes an approximation within the deviation in the range or value
known or
expected in the art from the measurements method; (d) the words "herein",
"hereby",
"hereof", "hereto", "hereinbefore", and "hereinafter", and words of similar
import, refer
to this specification in its entirety and not to any particular paragraph,
claim or other
subdivision, unless otherwise specified; (e) descriptive headings are for
convenience
only and shall not control or affect the meaning or construction of any part
of the
specification; and (f) "or" and "any" are not exclusive and "include" and
"including" are
not limiting. Further, The terms "comprising," "having," "including," and
"containing"
are to be construed as open-ended terms (i.e., meaning "including, but not
limited to,")
unless otherwise noted.
[0039] To the extent necessary to provide descriptive support, the subject
matter
and/or text of the appended claims is incorporated herein by reference in
their entirety.
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[0040] Recitation of ranges of values herein are merely intended to serve
as a
shorthand method of referring individually to each separate value falling
within the
range, unless otherwise indicated herein, and each separate value is
incorporated into
the specification as if it were individually recited herein. Where a specific
range of
values is provided, it is understood that each intervening value, to the tenth
of the unit
of the lower limit unless the context clearly dictates otherwise, between the
upper and
lower limit of that range and any other stated or intervening value in that
stated range,
is included therein. All smaller sub ranges are also included. The upper and
lower limits
of these smaller ranges are also included therein, subject to any specifically
excluded
limit in the stated range.
[0041] Unless defined otherwise, all technical and scientific terms used
herein have the
same meaning as commonly understood by one of ordinary skill in the relevant
art.
Although any methods and materials similar or equivalent to those described
herein can
also be used, the acceptable methods and materials are now described.
[0042] All methods described herein can be performed in any suitable order
unless
otherwise indicated herein or otherwise clearly contradicted by context. The
use of any
and all examples, or exemplary language (e.g., such as") provided herein, is
intended
merely to better illuminate the example embodiments and does not pose a
limitation on
the scope of the claimed invention unless otherwise claimed. No language in
the
specification should be construed as indicating any non-claimed element as
essential.
Definitions:
[0043] Annular groove ¨ in the context of the present technology, an
annular groove
can extend fully or partially around the circumference of the handle. The
smallest
annular groove is a notch.
Detailed Description:
[0044] A typical prior art endodontic file, generally referred to as 8, is
shown in Figure 1.
The file includes a handle 10 that is at a proximal end 12 of a shank,
generally referred
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to as 16. A distal end 14 of the shank 16 is of a substantially reduced
diameter
compared to the proximal end 12. The shank 16 is an electrically conductive
metal.
[0045] The external surface of shank 16 is smooth in a proximal region 18.
The proximal
region 18 is 7 mm long and extends from the proximal end 12 to a fluted region
20. The
proximal region 18 is provided with a series of gaps 22. The gaps 22 are in a
series with
three spaced 1 mm apart and a fourth spaced 2 mm, with the large spacing 24
being
proximal to the narrower spacings 24. The fluted region 20 has a plurality of
at least
two equally spaced apart continuous helical flutes 26. These helical flutes
extend from
the proximal region 18 to the distal end 14. There are different shapes and
depths of
flutes 26 in addition to different widths of the shank 16, depending upon the
manufacturer. The shank 14 is an electrically conductive metal.
[0046] Slidably received on the shank 16 and illustrated as being adjacent
handle 10 is
an elastomeric washer 30 that is used by the practitioner to mark the depth of
penetration of the shank 16 into the root canal.
[0047] In one size of endodontic file 8 the shank 16 is 25 mm long from the
handle 10 to
the distal end 14 and the washer 30 is 1 mm wide. As the file 8 is worked into
the root
canal the practitioner can move the washer 30 down against the crown of the
tooth to
provide an accurate indication of the depth that the file has penetrated into
the root
canal, as long as it has penetrated between approximately 17 and 24 mm.
[0048] In another size, the endodontic file 8 has a shank that is 21 mm
long. This allows
for accurately measuring the depth of the root canal if the root canal is
between 13 and
20 mm deep. Again, as the file 8 is worked into the root canal the
practitioner can move
the washer 30 down against the crown of the tooth to provide an accurate
indication of
the depth that the file has penetrated into the root canal.
[0049] In yet another size, the endodontic file 8 has a shank that is 31 mm
long. This
allows for accurately measuring the depth of the root canal if the root canal
is between
23 and 30 mm deep. Again, as the file 8 is worked into the root canal the
practitioner
can move the washer 30 down against the crown of the tooth to provide an
accurate
indication of the depth that the file has penetrated into the root canal.
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[0050] The handle 10 is typically formed of plastic and is of increased
diameter and
usually includes a surface configured to be easy to grasp and in which
slippage is
reduced. The shank 16 extends substantially along the length 17 of the handle
10, as
shown in Figure 2.
[0051] As shown in Figure 2, the current technology provides an annular
groove 28 in
the handle 10. The annular groove 28 may extend the full circumference of the
handle,
or may extend partially around the handle, or may be a notch 32, as shown in
Figure 3,
the requirement being that it extends along the circumference enough for the
clip of the
apex locator to make electrical contact with the exposed shank 17. Therefore,
any
length of notch from the smallest useable to an annular groove and all sizes
in between
are contemplated.
[0052] The annular groove 28 can be located anywhere along the length 34 of
the
handle 10, for example, but not limited to 4 mm from the proximal end 12 of
the shank
16 (4 mm from the distal end 34 of the handle 10). The annular groove 28 can
be
between about 1 and about 2 mm wide or any widths therebetween, preferably 2
mm.
It must be deep enough to achieve the following: 1. To allow an electrical
connection
between the exposed shank 17 and the clip of the apex locator; 2. To minimize
or
prevent contact between the exposed shank 17 and the patient's mouth parts;
and 3. To
minimize or prevent the clip from slipping. Similarly the width of the annular
groove 28
(that extends at least a part of the circumference of the handle) has to be
selected to
achieve the following: 1. To allow an electrical connection between the
exposed shank
17 and the clip of the apex locator; 2. To minimize or prevent contact between
the
exposed shank 17 and the patient's mouth parts; and 3. To minimize or prevent
the clip
from slipping. The side walls 33 of the annular groove 28 are preferably
substantially
normal to the exposed shaft 17, again to reduce the exposure of the exposed
shaft 17 to
the patient's mouth parts, and to minimize slippage of the clip.
[0053] As shown in Figure 4, the annular groove 28 extends the depth
measuring
capability 34 of the file 8 in a tooth 36 to 14 mm as compared to the standard
capability
36 of 7 or 8 mm. For a 25 mm file, this allows measuring depths between 17 mm
and 30
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mm or 31 mm. Hence, it can be used on patients having root canals ranging from
17
mm to 31 mm, thereby bridging the two most commonly used sizes of files, those
being
the 25 mm and the 31 mm files. Alternatively, a 21 mm endodontic file can be
provided
with the notch. The range of depths that can be measured is 13 mm to 26 mm or
27
MM.
[0054] Manufacturing of the handles to provide the present technology is
straightforward as the handle can be molded in two pieces, or molded with a
notch or
partial annular groove or can be molded in one piece followed with cutting the
annular
groove or notch or partial annular groove in the handle, both methods exposing
a
section of the shank.
[0055] In one exemplary example the notch embodiment is used. The
practitioner
probes the root canal, moving the washer 30 towards the handle 10 as the shaft
16
probes deeper into the root canal. The clip of the apex locator is placed on
the exposed
shaft 17 in the notch 32, which is located on any location along the length 34
of the
handle 10. This permits an electrical connection between the apex locator and
the shaft
16 of the file 8. A measurement is taken, and the clip is removed. The
practitioner will
repeat probing and measuring until the apex has been reached. Once the apex
locator
indicates that the apex has been reached, the practitioner removes the file 8
and
measures the distance between the distal end 14 of the file 8 and the washer
30. As the
clip is not located between the washer 30 and the handle 10, the practitioner
is able to
measure a greater range of depths with a single file than would be if a file
of the prior
art was employed.
[0056] Advantages of the exemplary embodiments described herein may be
realized
and attained by means of the instrumentalities and combinations particularly
pointed
out in this written description. It is to be understood that the foregoing
general
description and the following detailed description are exemplary and
explanatory only
and are not restrictive of the claims below. While example embodiments have
been
described in detail, the foregoing description is in all aspects illustrative
and not
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restrictive. It is understood that numerous other modifications and variations
can be
devised without departing from the scope of the example embodiment.
[0057] While example embodiments have been described in connection with
what is
presently considered to be an example of a possible most practical and/or
suitable
embodiment, it is to be understood that the descriptions are not to be limited
to the
disclosed embodiments, but on the contrary, is intended to cover various
modifications
and equivalent arrangements included within the spirit and scope of the
example
embodiment. Those skilled in the art will recognize, or be able to ascertain
using no
more than routine experimentation, many equivalents to the specific example
embodiments specifically described herein. Such equivalents are intended to be
encompassed in the scope of the claims, if appended hereto or subsequently
filed.
