U.S. patent number 3,812,858 [Application Number 05/300,181] was granted by the patent office on 1974-05-28 for dental electrosurgical unit.
This patent grant is currently assigned to Sybron Corporation. Invention is credited to Maurice Jules Oringer.
United States Patent |
3,812,858 |
Oringer |
May 28, 1974 |
DENTAL ELECTROSURGICAL UNIT
Abstract
Disclosed is a dental electrosurgical apparatus having means to
automatically regulate the proper amount of power needed to cut
soft tissues of the body, a timing device to regulate and
repeatedly interrupt the period of active current flow and a
regulator means that cuts off current flow when the patient is not
in contact with the inactive electrode.
Inventors: |
Oringer; Maurice Jules (New
York, NY) |
Assignee: |
Sybron Corporation (Rochester,
NY)
|
Family
ID: |
23158042 |
Appl.
No.: |
05/300,181 |
Filed: |
October 24, 1972 |
Current U.S.
Class: |
606/35;
606/39 |
Current CPC
Class: |
A61B
18/1233 (20130101); A61B 2018/00761 (20130101); A61B
2018/00886 (20130101) |
Current International
Class: |
A61B
18/12 (20060101); A61b 017/38 (); A61n
003/04 () |
Field of
Search: |
;128/303.14,303.16,303.17,303.18,422,423 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1,146,989 |
|
Apr 1963 |
|
DT |
|
1,178,528 |
|
Sep 1964 |
|
DT |
|
Primary Examiner: Pace; Channing L.
Attorney, Agent or Firm: Roessel; Theodore B. Aceto; Roger
Krawczyk; Charles C.
Claims
Having thus described the invention in detail, what is claimed as
new is:
1. In a dental electrosurgical unit including an RF power source,
an active electrode for applying power from said source to a
patient, and an inactive electrode for completing the circuit from
the patient back to the RF power source, the improvement
comprising:
a. circuit means connecting said RF power source to said active and
inactive electrodes so that the output power thereof is a function
of the patient tissue resistance through which said RF power
passes; and
b. timer means periodically interrupting the delivery of RF power
from said RF power source to said active electrode throughout the
operating procedure in a timed cycle to control the time duration
during which incisions can be made with the active electrode,
wherein said timer means interrupts the flow of RF power to said
active electrode for a period of time to allow the dissipation of
heat from the tissue prior to the subsequent application of
additional RF power by said active electrode, so that excessive
heat damage to the tissue is prevented.
2. A dental electrosurgical unit as set forth in claim 1 wherein
said circuit means connects a RF power regulator in series with the
RF power source, a switch means is connected in series between said
RF power source and said RF power regulator, and said timer means
operates to cycle said switch means "on" and "off" throughout the
operating procedure with the "off" portion of the cycle wherein the
delivery of RF power to said active electrode is interrupted, is
longer than the "on" portion of the cycle.
3. A dental electrosurgical unit as set forth in claim 2 wherein
said timer means cycles said switch to permit delivery of RF power
to said active electrode for between 0.5 and 1 second and
thereafter interrupts the delivery of RF power to said active
electrode for between 2.5 and 5.0 seconds.
4. A dental electrosurgical unit as set forth in claim 2 including
alarm means operable when RF power is being delivered to said
active electrode for sensing flow of RF power through said inactive
electrode and terminating flow to said active electrode when flow
of RF power through said inactive electrode is not sensed.
5. A dental electrosurgical unit as set forth in claim 4 wherein
said alarm means is operatively connected to a switch located in
series between said RF power source and RF power regulator.
6. A dental electrosurgical method comprising the steps of:
a. applying RF power to the patient tissue through an active
electrode;
b. increasing and decreasing said power applied to the patient
tissue as a function of the resistance of the tissue being operated
on; and
c. periodically cycling te flow of RF power to the tissue on and
off in a timed cycle throughout the operating procedure to limit
the time duration during which incisions can be made to the patient
tissue so that the tissue is allowed to dissipate heat between
incisions to prevent excessive heat damage to the tissue.
7. A method as set forth in claim 6 wherein the flow of RF power is
cycled on for between 0.5 and 1.0 seconds and is cycled off for
between 2.5 and 5 seconds throughout the operating procedure.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to electrosurgical devices
and more particularly to a dental electrosurgical device which
greatly minimizes the danger to the patient of an electrosurgical
procedure in the oral cavity.
Much of the danger of oral electrosurgery can be attributed to the
physical characteristics of the oral tissue. For example, the
gingival mucosa is exceedingly thin and is attached to periosteum
which is in turn attached to viable bone that usually contains
vital teeth. Such tissue is very thin and highly vulnerable to
penetration by the electrosurgical heat and consequently very
easily damaged. Thus, any electrosurgical procedure or treatment
involving gingival tissue requires extremely precise
electrosurgical techniques to avoid destructive damage to this
tissue and underlying structures by heat penetration. For example,
if insufficient power is used and the tissue cells in the path of
the RF current are not volatilized as would occur in an efficient,
safe cleavage of tissue, the organic content of the tissue cells
are merely coagulated causing extensive destruction. On the other
hand, excessive power causes charring and burning of the tissue
which results in unnecessary and undesired tissue and bone
destruction.
Tissue is also destroyed if the active electrode is applied too
slowly. In this respect, a slow application of the electrode to the
relatively thin gingival tissues allows the heat being generated to
penetrate laterally far beyond the point of contact so that the
heat penetrating through the tissue is likely to cause severe
damage to the underlying tissue, bone and tooth structures. This
same penetration of heat can occur if the electrode is repeatedly
applied to the tissue without intervening intervals sufficient to
permit the heat to dissipate. Thus, even though the electrode is
used rapidly enough for each contact the continued repetition
results in an accumulation of retained heat in the tissues that may
penetrate and destroy the underlying structures.
For proper control and efficiency of the cutting and colagulating
currents used in dental electrosurgery a dispersive or inactive
electrode must be applied to the patient's body. The RF current
then enters the patient's body through the active electrode and
passes out of the body through the inactive electrode and back
directly to the power source. Should the patient inadvertently lose
contact with the inactive electrode or if the operator forgets to
employ it, the subsequent loss of precise control and cutting
efficiency is likely to cause damage to the patient.
These drawbacks and other dangers inherent in existing dental
electrosurgical units are overcome in the present invention which
provides for an automatic regulation of the power delivered to
active electrode in direct proportion to the changes in resistance
in the tissue being operated upon. In addition, the present
invention has a duty timer which continuously interrupts the flow
of current during the operating procedure. The interruption of the
cutting current prevents heat build-up and instead allows
sufficient time between applications of RF current to permit
dissipation of the heat generated during the surgical procedure
thereby reducing the danger of possible injury to the patient.
Also, the timer makes the electrosurgical apparatus safer in the
hands of a novice or an inexperienced electrosurgical practioner.
In this respect, the interruption of the cutting current will
automatically compensate for any tendency on the part of the novice
to keep the electrode in contact with the tissue for periods of
time sufficient to allow the penetration and build-up of heat
resulting in unnecessary destruction of tissue. The present
invention also employs an alarm means to cut off current flow
whenever the patient has lost contact with the inactive
electrode.
SUMMARY OF THE INVENTION
The present invention may be characterized in one aspect thereof by
the provision of a dental electrosurgical unit having a power
regulator acting responsive to the changes in the resistance of the
patient tissue through which the RF current is passed to
automatically increase or decrease the power applied to the active
electrode in direct proportion to the tissue resistance; a timing
device for regulating the period of active current flow and
repeatedly interrupting flow of RF current into the patient tissue;
and safety means for terminating the flow of RF current to the
patient when the patient is not in contact with the indifferent
electrode.
OBJECTS OF THE INVENTION
One object of the present invention is to provide a dental
electrosurgical apparatus having a power regulator which varies the
electrosurgical RF power in direct proportion to the resistance of
the tissue being operating upon.
Another object of the present invention is to provide a dental
electrosurgical apparatus wherein the flow of RF current to the
tissue being operating upon is intermittent.
A further object of the present invention is to provide a dental
electrosurgical unit wherein the flow of RF current is cycled on
and off during the operation procedure with the off cycle being
longer than the on cycle.
A still further object of the present invention is to provide a
dental electrosurgical apparatus having means to automatically
terminate current flow when the patient is not in contact with an
indifferent electrode.
The yet further object of the present invention, is to provide a
dental electrosurgical apparatus which minimizes the possibility of
burn injury to the patient even when used by a novice operator.
These and other objects and advantages and characterizing features
of the present will become more apparent upon consideration of the
following detailed description thereof when taken in connection
with the accompanying drawing depicting the same.
DESCRIPTION OF THE DRAWINGS
The sole FIGURE is a schematic representation of the
electrosurgical equipment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings, the sole FIGURE shows the dental
electrosurgical apparatus of the present invention generally
indicated at 10. The apparatus includes an RF generator 12 of the
type well-known in the art. It is sufficient for purposes of the
present invention merely to say that such an RF generator suitable
for purposes of dental electrosurgery should produce an RF signal
on the order of 1.75 MHz and approximately 90 watts of power.
The generator has an outlet 14 for delivering the RF current in
series through a conductor 16, a control switch 18 and a duty cycle
timer switch 20 to a power regulator 22. The function of the power
regulator will be set out herein below.
From power regulator 22, the RF current passes in series to the
active electrode 24. The active electrode is, in turn manipulated
by the operator for cutting or coagulating the patient tissue
schematically illustrated at 26. RF current from the active
electrode passes through the patient into a indifferent or inactive
patient electrode 28 and then back through line 30 to the RF
generator.
The usual practice in oral electrosurgery is for the operator to
select in his judgement an appropriate power requirement and then
adjust the RF generator accordingly. The power output of the
generator then remains constant throughout the operative procedure.
Various devices are used in the prior art to maintain the power
output constant, for example, the RF current can be monitored and
appropriate electronics provided to square the current in order to
obtain an approximation of the power. This I.sup.2 value is then
used to either increase or decrease the output of the RF generator
in order to keep the power relatively constant. However, such
devices ignore the resistance value of the tissue being operated
upon and the electrosurgical expertise of the user. For example, as
the thickness of the oral tissue varies, the resistance will also
vary. Consequently, if the power applied is kept constant, the
current density in the thinner tissue will be greater than the
current density in the thicker tissue. As set out herein above, the
gingival tissue is exceedingly thin and highly vulnerable to
penetration by heat so that using the same power to cut through the
thin tissue as is used to cut through thicker tissue could result
in serious damage to gingival tissue and to the underlying
peristum.
In the present invention, power regulator 22 is of the type which
increases or decreases the RF current being applied to active
electrode 24 in direct proportion to the increase or decrease in
resistance of the tissue being operating upon. Accordingly, once
the initial power requirement is set at the RF generator, the RF
current applied to the active electrode will automatically increase
when the resistance of the patient tissue increases and decrease
when the resistance of the patient tissue decreases. Such power
regulator devices are well within the skill of the art and may be,
for example, a constant voltage device which will increase or
decrease the current in direct proportion to the resistance being
encountered.
As set out herein above, the RF current to power regulator 22
passes first through a cycle timer switch 20. The switch is
operated by a duty cycle timer 32 which repeatedly opens and closes
switch 20 during the operation of the electrosurgical device.
Preferably the duty cycle timer 32 is programmed to close the
switch for between 0.5 and 1.0 seconds and then to open the switch
for a period ranging from 2.5 to 5 seconds. This one second on,
five seconds off cycle of operation, for example, will permit a
sufficient interval between the application of RF current to allow
a dissipation of heat. Such an arrangement greatly reduces the
possibility of injury to the patient caused by keeping the active
electrode in contact with the patient for relatively long periods
of time or applying the electrode to the tissue repeatedly without
a sufficient intervening interval to permit the heat to
dissipate.
In operating the device thus far described, the operator simply
closes switch 18 which may be, for example, a foot switch. With
switch 18 closed, the operator manipulates active electrode 24 and
performs the electrosurgical procedure. With the active electrode
in contact with the patient, the RF current flows from generator 12
in series through conductor 16, switches 18 and 20 power regulator
22, through the active electrode 24 to the patient and then from
the patient through the inactive electrode 28 and back to the
generator through return lines 30. During the operating procedure,
duty cycle timer 32 operates to repeatedly open and close switch 20
in a programmed cycle designed to close the switch for 0.5 to 1.0
seconds and open the switch for about 2.5 to 5 seconds. The power
regulator 22 in turn acts responsive to any increase or decrease in
the resistance of the patient tissue to increase or decrease
respectively the power being delivered to the active electrode 24.
In this manner, the device thus far decribed will greatly reduce
the possibility of burn damage to the oral tissue by reducing the
RF current being utilized during the procedure and by discontinuing
the application of the current for a time interval sufficient to
permit dissipation of the heat generated during the operating
procedure.
While the dental electrosurgical device may operate even though the
patient is not in contact with the inactive electrode 28, best
results and consistently efficient operation are achieved when the
patient is in contact with the inactive electrode 28. This allows
RF current to radiate through the patient's body and return
directly to the generator. To insure that the RF current is not
applied to the patient unless he is in contact with the inactive
electrode 28, the present invention employs an alarm system which
includes an alarm device 34 connected on one hand through line 36
to the inactive electrode and on the other hand, through a line 38
to a switch 40 in line 16. Alarm device 34 may be any suitable
electronic regulator for sounding an alarm and opening switch 40
whenever the patient is not in contact with the inactive electrode.
For example, the alarm device 34 could include means to detect RF
power flowing through the inactive electrode. With this
arrangement, the alarm will sound and switch 40 will open whenever
switches 20 and 22 are closed and no power is detected flowing
through the inactive electrode. For proper function of course,
alarm 34 should function only when both switches 18 and 20 are
closed. Otherwise, the alarm would sound each time either switch is
open and no RF power is flowing through the patient. For this
reason alarm 34 is shown connected by a line 42 to line 16 between
switch 20 and power regulator 22.
Various modifications in the arrangement shown should be readily
apparant. For example, the function of switches 18 and 20 could be
incorporated into a single switch structure. In such a
construction, alarm 34 could be connected to this switch for making
the alarm sensitive to RF power flow through the inactive electrode
only when the single switch structure is closed.
Thus, it should be appreciated that the present invention
accomplishes its intended objects in providing a dental
electrosurgical device which greatly minimizes the risk of injury
to the patient. Having an electrosurgical unit which incorporates a
power regulating device for varying the power output in direct
proportion to the resistance of the patient tissue insures that
excessive or inadequate power is not applied to the patient.
Providing a duty cycle timer insures a periodic interruption of the
RF current greatly reduces the possibility of excessive tissue
destruction caused by heat build up and retention in the
tissue.
* * * * *