Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND APPARATUS FOR DENTAL TREATMENT
USING HIGH PRESSURE LIQUID JET
Background of the Invention
The present invention relates to instruments for carrying out dental
procedures,
and more specifically to carrying out such procedures using a high pressure
liquid jet.
It is known in the prior art and in common dental practice to carry out most
treatments using mechanical techniques. For example, in endodontics, which
often
involves many root canal procedures, a diseased tooth is first diagnosed, and
then an
opening is drilled through the crown of the tooth into the pulp chamber
thereof. After the
tooth is isolated and the field sterilized, the pulp, consisting primarily of
blood-rich tissue
and nerve fiber and necrotic components, is then aspirated. There remains
within the
pulp chamber the primary nerve fibers and blood vessels that sustain the
tooth. These
tissues extend from extremely fine openings in the apex of the roots) of the
tooth
through a narrow channel(s), and cannot be removed solely by aspiration.
Typically, a file is then inserted into the narrow channels) to displace and
abrade
the nerve and blood vessel tissue. Increasingly larger files are inserted,
whereby the
narrow channels) is cleared of all soft tissue. After cleaning and
preparation, the pulp
chamber and root channels) are filled with a sterile solid material, and the
drilled
opening is filled with standard gold, silver, or other dental filling
preparations.
This typical procedure is labor-intensive, resulting in a high cost factor for
the
dentist's time as well as skill and experience. Moreover, the procedure may be
painful,
and sufficient local anesthetic must be injected to completely numb the area
of the tooth
for the relatively long time that the procedure requires.
Complications known to result from a root canal procedure may include
infection
arising from incomplete removal of the diseased tissue within the canal and
pulp
chamber, or the introduction of other infectious bacteria into those spaces
during the
procedure. In addition, the dentist may inadvertently perforate the tooth;
e.g., by driving
a file instrument through the apical opening at the base of the root, and the
opening thus
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formed may provide a vector for renewed infection and inflammation. Not
infrequently,
drug therapy including a strong antibiotic is prescribed after the procedure
to forestall
these complications. Other complications include broken instruments lodged in
the
tooth, or fracture of the root or body of the tooth.
Recent innovations in this dental procedure include the use of laser light
delivered
into the pulp chamber and root channel by an optical fiber. The high power
optical
energy vaporizes the pulp and nerve tissue, and is inherently sterilizing.
However, the
products of tissue combustion may contaminate the interior of the chamber and
root
channel, and the laser pulses may not contact all of the tissue in the narrow
root channel,
causing very unsatisfactory results. To avoid these results, there is a
tendency to apply
an excess of laser energy, which may overheat the tooth and surrounding tissue
and cause
necrosis. In addition, laser energy impacting on pre-existing metallic
fillings may cause
dangerous reflected beams and unforeseen damage.
As another example, in periodontal practice, which typically includes
gingivectomy procedures, the gingiva are usually resected using a scalpel, and
scaling
and root planing are accomplished with specialized steel tools. These
procedures and
most other dental procedures are executed with mechanical drills, burrs, and
cutting
wheels.
Innovations such as ultrasound-driven scaling instruments, high power lasers
for
caries removal, and the like have not substantially altered the reliance of
the dental
profession on the same mechanical tools that have been in use for almost a
century. All
such mechanical tools generate high levels of vibration and sound that are
directly
conducted through bone to the ears of the patient, resulting in patient
comfort problems.
Also, the mechanical tools, as well as ultrasound tools, generate substantial
amounts of
heat in very localized areas, causing direct pain stimulation. Water spray
devices are
provided to remove this heat, but may not be effective at the point source of
the heat. In
this regard, the heat generated by dental lasers may pose the greatest
problem.
Clearly the prior art shows an unmet need for improved dental instruments that
can carry out a wide range of dental treatment procedures without generating
heat, noise,
and vibration as they operate on the patient's teeth.
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Summary of the Present Invention
The present invention generally comprises an apparatus and methods for dental
treatments that overcome the problems associated with current mechanical and
dental
techniques and instruments. In one aspect, the invention comprises a technique
for
removing the soft tissue from within a human or animal tooth, whereby
infectious,
inflamed and necrotic tissue may be removed and the tooth and periodontal
structures
restored to a healthy condition. A salient aspect of the invention is that the
invention
obviates the need for files and other mechanically abrasive displacement
tools,
employing instead a high pressure jet of water or other liquid directed at the
soft tissue
within the tooth to excise, emulsify and aspirate the soft tissue. The soft
tissue may
comprise the pulp, nerve tissue and blood vessels that extend from the
surrounding jaw
bone through the apex of each tooth root into the root channel and to the pulp
chamber of
the tooth.
The invention provides a dental hydrojet tool having a handpiece and a cannula
extending therefrom. The cannula is connected to a source of high pressure
water or
other liquid, and includes a distal orifice to deliver a high velocity, high
pressure jet. The
pressure range of the high pressure source is approximately 500-60,000 psi,
and the jet
orifice is approximately 10-800 microns in diameter. The cannula may also
provide
aspiration to remove the fluid from the jet as well as tissue, or aspiration
may be provided
by a second cannula connected to a vacuum aspiration unit. An exemplary device
is
described in U.S. Patent No. 5,562,692, commonly assigned herewith.
To initiate the method of the invention, a tooth that is diagnosed as diseased
and in
need of a pulpectomy/root canal procedure is opened; that is, a hole is made
in the crown
of the tooth using a standard dental grinding or drilling instrument. The
tooth is then
isolated using a dental dam or similar protective shield.
The cannula of the hydrojet tool is then directed through the newly formed
hole in
the crown of the tooth, and a jet of liquid is directed at the pulp and nerve
and vascular
tissue within the interior chamber of the tooth. The fluid may comprise
medical-grade
saline solution, and/or a disinfectant solution and/or an antibiotic solution
and/or an
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abrasive solution. In the pressure range and jet diameter formed by the
hydrojet tool, all
the soft tissue within the tooth is cut, excised, emulsified, and aspirated
out of the tooth.
Aspiration may be provided by the hydrojet tool, or by the cannula of a
standard dental
aspiration device.
A salient aspect of the method of the invention is that the hydrojet easily
removes
all the soft tissue within the tooth, but is limited in its ability to cut or
erode the hard
calcified tooth tissue. Likewise, the jet lacks the velocity to cut through
the apical root
openings through which the nerve fibers and blood vessels enter the root
channels from
the surrounding jaw tissue. As a result, this process of pulpectomy/root canal
progresses
to a self-limiting extent and for example, cannot pierce the apical openings
if they are
naturally closed, whereby a source or complications known to result from prior
art
procedures. In addition, the use of antiseptic or antibiotic solutions reduce
the possibility
of post-procedure infection if the apical openings where to be damaged.
Moreover, the time required to excise, emulsify, and aspirate all the soft
tissue
within a typical molar is on the order of 10-240 seconds, so that far less
time and labor is
expended in the procedure. This reduction in time to complete the removal step
reduces
the need for local anesthesia, reduces the time that the patient may
experience pain (if
any), and overall increases throughput in a dental practice.
The interior chamber of the tooth is then completely aspirated and verified
for
completion of removal of all soft tissue. The interior chamber is then packed
with an
appropriate filler material known in the prior art, and the opening in the top
of the tooth
is filled or provided with a prosthetic crown, as is known in the dental art.
It should be noted that the fluid jet may comprise a pulsed jet formed by a
pulse
intensifier device in the handpiece of the dental hydrojet tool, as described
in the US
patent to Bair referenced above. Alternatively, the handpiece may be connected
to a
source of high pressure fluid to form a steady stream jet emanating from the
orifice. The
handpiece may be directed at other surfaces and structures to carry out
endodontal,
periodontic, surgical, and restorative procedures such as gingivectomy,
removal of
granulation tissue, muco-osseous surgery, caries removal, scaling and removal
of plaque
and calculus, and extractions and tissue incisions.
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Brief Description of the Drawing
Figure 1 is a cross-sectional elevation of a typical human tooth prior to
undergoing
the pulpectomy/root canal procedure of the present invention.
5
Figure 2 is a cross-sectional elevation as in Figure 1, showing the step of
creating
an opening through the top of the tooth to the pulp chamber within.
Figure 3 is a cross-sectional elevation as in Figures 1 and 2, showing the
cannula
of the dental hydrojet tool being extended through the upper opening of the
tooth and
being actuated to emit a high pressure, high velocity jet.
Figure 4 is a cross-sectional elevation as in Figures 1-3, showing the soft
tissue
within one root channel and a portion of the pulp chamber emulsified and
undergoing
aspiration.
Figure 5 is a cross-sectional elevation as in Figures 1-4, showing the soft
tissue
within both root channels and all the pulp chamber emulsified and undergoing
aspiration.
Figure 6 is a cross-sectional elevation as in Figures 1-5, showing the pulp
chamber
and root channels packed with filler material and the upper opening filled at
the
completion of the procedure.
Figure 7 is a functional block diagram of an electrically driven system for
operating the high pressure jet dental instrument of the present invention.
Figure 8 is a functional block diagram of a pneumatically driven system for
operating the high pressure jet dental instrument of the present invention.
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Figure 9 is a cross-sectional elevation of one embodiment of the fluid
reservoir
depicted in Figures 7 and 8.
Figure 10 is a cross-sectional elevation of another embodiment of the fluid
reservoir depicted in Figures 7 and 8.
Figure 11 is a cross-sectional elevation of a further embodiment of the fluid
reservoir depicted in Figures 7 and 8.
Figure 12 is a cross-sectional elevation of one more embodiment of the fluid
reservoir depicted in Figures 7 and 8.
Figure 13 is a functional block diagram of a system for generating purified
water
for use in the fluid reservoir of the invention.
Figure 14 is a cross-sectional side view of the handpiece portion of the high
pressure jet dental instrument of the present invention.
Figure 15a-15d are cross-sectional side views of different embodiments of
output
tips of the dental instrument depicted in Figure 14.
Figure 16 a is an enlarged end view of a further embodiment of the output tip
of
the dental instrument depicted in Figure 14.
Figure 16b is a fragmentary cross-sectional view of the output tip, taken
along line
16b-16b of Figure 16a.
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Description of the Preferred Embodiment
The present invention generally comprises an apparatus and methods for dental
treatments that overcome the problems associated with current mechanical and
dental
techniques and instruments. In one aspect, the invention comprises a technique
for
carrying out a pulpectomy or root canal: that is, removing the soft tissue
within the tooth
by excising, emulsifying and aspirating the soft tissue.
With regard to Figure 1, a typical human tooth 10 is comprised of a crown 11
extending above the gum tissue 12, at least one root portion 13 received
within a
respective alveolus 14, and a neck portion 16 joining the root and crown at
the cemento-
enamel junction. The alveoli are deep depressions in the bone tissue of the
mandible 17,
and are lined with periosteum which is reflected on the tooth at the apex 18
of each root.
At the margin of the alveolus the periosteum becomes continuous with the
periodontal
ligament of the gum tissue 12. The hard tissue of the tooth includes the
dentine 21,
which provides the primary structure of the tooth, and the very hard enamel
layer 22
which forms a durable grinding surface and covers the crown 11 down to the
cemento-
enamel junction at the neck 16.
Within the dentine layer 21 there is defined a pulp chamber 26. Processes of
the
pulp chamber 26, termed the root canal 27, are disposed centrally in each root
13 and
extend through the respective apex 18 at a minute orifice, the apical foramen
28. The
chamber 26 and canals) 27 contain dental pulp, a soft, vascular tissue
containing
numerous nerves and blood vessels and other tissue components. The pulp
provides
enervation and sustenance to the tooth through the epithelial lining of the
pulp chamber
and canals.
The method of the present invention is used to treat a tooth that is diagnosed
as
diseased and requiring a pulpectomy/root canal procedure. With regard to
Figure 2, the
tooth is initially opened by employing a dental drill 31 or equivalent burr or
grinding
tool. The resulting opening 32 extends through the enamel and dentine to
provide access
to the pulp chamber 26 and root channels 27, as shown in Figure 3. A dental
hydrojet
tool 35 is provided, including a handpiece 33 having a cannula 34 extending
therefrom.
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The cannula includes a distal orifice adapted to generate a high velocity,
high pressure,
low volume jet 36 of liquid. The handpiece maneuvered to insert the cannula 34
into the
opening 32 to direct the jet 36 at the soft tissue within the chamber 26 and
channels 27.
The jet easily cuts through the soft tissue, and the energy and turbulence
engendered by
the jet causes the tissue to be emulsified upon contact. Moreover, the
turbulent liquid
easily penetrates into the narrow spaces of the root channels 27 (Figure 4),
effecting
thorough excision and emulsification of the nerve and vascular tissue therein.
The
cannula 34 may also provide vacuum aspiration to remove the emulsified tissue
and jet
fluid, or a second aspiration cannula may be employed.
In the preferred embodiment the pressure range of the high pressure jet is
approximately 500-60,000 psi, and the jet diameter is approximately 10-800
microns.
These parameters are selected to provide a liquid jet that is not capable of
cutting nor
detrimentally eroding the hard tissue of the tooth. As a result, the excision
and
emulsification action of the jet 36 cannot pass through the apical foramen 28
of the root,
if the foramen is naturally closed, and thus cannot injure the alveolar sac or
periosteum at
the base of the root. Thus a source of substantial post-operative
complications in prior
art procedures is completely eliminated by the self-limiting feature of the
invention.
The jet 36 acts quickly within the soft tissue, and the time necessary to
excise,
emulsify, and aspirate all the soft tissue within a typical tooth is
approximately 10-240
seconds. Of course, more time is required for teeth such as molars having a
plurality of
root channels 27. As shown in Figure 5, the dental hydrojet tool 35 may be
maneuvered
to direct the cannula 34 and jet 36 into each of the root channels to remove
all soft tissue
therein.
The liquid which constitutes the jet 36 may comprise sterile water or medical
grade saline solution, or an antiseptic solution, or an antibiotic solution,
or an abrasive
solution, or other medications or chemicals, or any combination thereof.
Furthermore,
more than one of these types of solutions may be used in serial order. For
example,
saline solution may be used for the excision and emulsification process,
followed by an
abrasive solution to scour the cavity, an antiseptic solution to eliminate
indigenous
bacteria and then an antibiotic solution to prevent regrowth of infective
agents. It should
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be noted that the fluid jet may comprise a pulsed jet formed by a pulse
intensifier device
in the handpiece of the dental hydrojet tool, as described in the US patent to
Bair
referenced above. Alternatively, the handpiece may be connected to a source of
high
pressure fluid to form a steady stream jet emanating from the orifice.
After the pulp chamber and root channels have been fully aspirated and
visualized
for verification of removal, the pulp chamber and root channels are packed
with an inert,
aseptic material 41, as is known in the dental art. Thereafter, the opening 32
is filled
using a standard dental material 42, such as silver amalgam, gold inlay or
crown, cured
composite material, or the like. The procedure is thus completed.
The use of the dental hydrojet to perform the pulpectomy/root canal procedure
exhibits the following advantages over prior art techniques:
1 ) Complete removal of all soft tissue within the pulp chamber and root
channels;
2) Rapid completion, resulting in reduced use of anesthetic and reduced pain
experienced by patient, and reduced cost of skilled dentist and office
overhead expenses;
3) Elimination of complications due to perforation of root or apical foramen;
4) Sterilization of operating field by use of appropriate jet liquids to
minimize
post-operative infection.
With regard to Figure 7, an apparatus for carryout out the procedure described
above includes a fluid reservoir 51 for supplying the working fluid to the
dental hydrojet
instrument 35. The fluid from reservoir 51 is fed to a pressure pump 52 to
raise the fluid
pressure to the range indicated above: The pump 52 is controlled by electrical
controls
53 set by the system operator or dentist. A pressure regulator 54 limits the
output
pressure of the pump 52, and a safety valve 56 provides a pressure cutout
function if a set
of safety conditions are not present. The pressurized fluid is fed from the
safety valve 56
to a control valve 57. The pressurized fluid output from the control valve 57
is fed
selectively via a flexible tubing 61 to the dental hydrojet tool 35, which
emits the high
pressure jet 36 under the direction of the dentist or other trained
practitioner.
Output of the control valve 57 is provided on demand of the user by a switch
58,
such as a footswitch or an on-off switch on the tool 35. The control valve has
the further
function of a pressure dump to immediately relieve pressure in the line 61
whenever the
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switch 58 is turned off, whereby the high pressure jet 36 is squelched
instantaneously. In
situations where a more immediate and precise cutoff of the jet 36 is
required, a shutter
valve 59 may be provided at the output end of the hydrojet tool 35 to
mechanically block
the jet output.
5 With regard to Figure 8, an apparatus for carrying out dental procedures is
depicted which is similar to the apparatus of Figure 7, and common elements or
components are provided with the same reference numerals having a prime ( ')
designation. The primary distinction of the apparatus of Figure 8 is the
provision of an
pressurized air source 62, which feeds pneumatic pressure through a pressure
regulator
10 63 to drive a pneumatically operated pressure pump 52'. The remaining
components
operate substantially as described with reference to Figure 7.
Either of the apparatus described in Figures 7 or 8 may be housed in a small
cabinet adapted in size and shape to be placed in a dental office or medical
office.
With regard to Figure 9, one embodiment 70 of the fluid reservoir 51 or 51'
includes a tank 66 having a charge of fluid 67 retained therein. A stopper 68
seals the
tank opening, and a delivery tube 69 extends through the stopper to the bottom
of the
tank 66. Another tube 71 extends through the stopper to pressurize the head
space in the
tank and cause the fluid 67 to flow through the delivery tube 69 to the
pressure pump 52
or 52'.
A further embodiment 75 of the fluid reservoir, shown in Figure 10, includes
some
components similar in function to those of Figure 9, and are provided with the
same
reference numerals with a prime( ') designation. The tank 75 holds a charge of
abrasive
solution 73 for use in those procedures which benefit from an abrasive fluid
jet. The
abrasive solution is stirred by a mechanical stirrer device, as in known in
the prior art,
and may comprise agitating balls which are magnetically driven by an external
magnetic
device, or may comprise agitating paddles, or may comprise a device for
rocking or
oscillating the tank 75 to maintain the abrasive compound suspended in the
fluid.
With regard to Figure 11, another embodiment 76 of the fluid reservoir of the
invention includes a sealed bag 77 of premixed fluid 78 for use by the
hydrojet
instrument. The bag 77 is placed in a sealable vessel or pressure transfer
tank 79, and a
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discharge port 81 extends from within the bag 77 through the vessel to connect
to the
pressure pump 52. The vessel 79 includes a port 82 connected to a pressurized
fluid
source, such as the output of the safety valve 56 or 56', whereby the pressure
within the
vessel causes the premixed fluid 78 to flow from the discharge port 81 at the
regulated
pressure of the pump 52. In this arrangement the fluid in reservoir 51 or 51'
need not be
sterile, as the sealed bag 77 prevents contamination of the premixed fluid 78.
A simplified source of hydrojet fluid, shown in Figure 12, comprises a bag 83
of
premixed jet fluid 84. The bag includes a seal 86 at one end, through which a
drain tube
87 extends to connect the fluid 84 to the pump 52. The bag further includes
means such
as holes 88 at the other end of the bag to facilitate hanging the bag in
inverted fashion, as
shown, similar to an IV bag, whereby the fluid will drain gravitally from the
bag 83.
A further aspect of the invention is the provision of a system for producing
the
sterile fluid used in the dental hydrojet tool 35. With regard to Figure 13, a
tank 91 is
filled and replenished by a source 92 of de-ionized water. A chlorine injector
93 adds
chlorine gas or a chlorine compound to the tank to provide primary water
purification. In
addition, a pump 94 draws water from the tank and delivers it to an
ultraviolet light
sterilizer 96. As the water passes from the sterilizer 96 back to the tank 91,
an ozonator
97 adds ozone to the water to further sterilize the liquid. The combination of
chlorine,
UV light, and ozone is effective in eliminating bacterial, viral, and
parasitic organisms
from the water, thereby reducing to an absolute minimum the opportunity for
infection
from use of the dental hydrojet tool. The sterile fluid is drawn from the tank
91 by a
pump 98 and passed through a sub-micron filter 99, and thence fed either
directly to the
reservoir 52 or 52', or to any of the reservoir embodiments disclosed herein.
With reference to Figure 14, the handpiece 33 of the dental hydrojet
instrument 35
includes a tubular barrel 101, and a tubing connector 102 joined
concentrically to a
proximal end of the barrel 101. A jet tube 103 extends distally and
concentrically from
the connector 102, and is maintained centered in the barrel by a plurality of
spider
spacers 104 and spacing lugs 106. The connector 102 is adapted to be joined to
the
tubing 61 that supplies high pressure fluid, and the jet tube 103 extends to
the distal end
of the cannula 34. The interior space 107 of the barrel 101 comprises an
evacuation
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channel for fluid and debris, and is joined through connector 108 to a vacuum
aspiration
system.
The distal end of the cannula 34 extending from the handpiece 35 may be
provided with various angular conformations, as shown in Figures 15a-lSd. With
reference to Fig. 15a, the tip 34a may be angled at approximately 0°-
60° from the axis of
the instrument, with the distal end of the jet tube 103 generally flush with
the distal
opening of the cannula. The open end of the cannula provides aspiration and
removal of
the fluid and debris through channel 107 and connector 108. As shown in Fig.
15b, the
cannula tip 34b may extend linearly with the axis of the instrument, with the
jet tube 103
extending distally of the end of the tip of the cannula. The extended jet tube
provides
enhanced visualization of the hydrojet and its impingement on the target.
Moreover, in
the root canal procedure described above the extended jet tube may be inserted
into the
pulp chamber and root canals, thereby facilitating completion of the
procedure. Figures
15c and 15d depict cannula tips 34c and 34d, each including an angular bend of
60°-120°
to extend into an opened tooth and to reach other more obscure targets within
the mouth.
In addition the tip 34d is provided with a curved portion adjacent to the tip.
With regard to Figures 16a and 16b, a further embodiment of the distal end of
the
cannula 34 includes a jet-forming nozzle 111 extending at a right angle to the
cannula 34
and coupled to the jet tube 103. Extending about the nozzle 111 is a bell-
shaped shield
112 having a curved conformation such as any conic section curve and formed
preferably
of transparent plastic or the like. A gap 113 between the shield 112 and the
jet nozzle
111 provides an aspiration intake port, and is connected to the aspiration
channel 107 of
the cannula. The shield captures a large amount of the spray created by the
hydrojet
impact on a target, while the transparent plastic permits visualization of the
target.
It may be appreciated that the dental hydrojet instrument disclosed herein may
be
employed to carry out other treatments and procedures in addition to root
canal and
pulpectomy. For example, the fluid jet is exceptionally well suited to carry
out removal
of calculus and plaque, and for root planing. This process may be enhanced
through the
use of an abrasive solution as the fluid for the fluid jet. Likewise, the
fluid jet may be
used for excision and resection of the gingiva, removal of granulated tissue,
as well as
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muco-osseous surgery. The fluid jet may also be an adjunct to tooth
extraction, in that
the jet may be used to sever the fibrous attachments to the tooth root,
thereby easing the
subsequent extraction. These procedures may be aided by the use of antibiotic
solutions
to form the fluid jet.
Furthermore, a fluid jet of sufficient energy may be used to remove carious
dental
tissue, thereby providing simple caries removal and preparation for filling.
It has been
found that proper choice of jet energy selectively removes the carious tissue
while the
health surrounding enamel and dentine may remain unscathed by the jet. This
process
may be enhanced through the use of an abrasive solution as the fluid for the
fluid jet.
The dental hydrojet instrument provides all of these treatment options, as
well as
the root canal/pulpectomy procedure, while creating virtually no heat or
vibration at the
target site. This characteristic is a notable advance over prior art
mechanical tools,
ultrasound instruments, and dental lasers.
The foregoing description of the preferred embodiments of the invention has
been
presented for purposes of illustration and description. It is not intended to
be exhaustive
or to limit the invention to the precise form disclosed, and many
modifications and
variations are possible in light of the above teaching without deviating from
the spirit and
the scope of the invention. The embodiments described are selected to best
explain the
principles of the invention and its practical application to thereby enable
others skilled in
the art to best utilize the invention in various embodiments and with various
modifications as suited to the particular purpose contemplated. It is intended
that the
scope of the invention be defined by the claims appended hereto.
