Note: Descriptions are shown in the official language in which they were submitted.
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PERIOTOME
TECHNICAL FIELD
This invention relates to an instrument and method for dental exodontia for
the extraction of
teeth. More specifically, the inventive instrument is designed to achieve the
cutting of the
fibrous attachment of the tooth to bone, formed of thousands of microscopic
fibers, collectively
referred to as the periodontal ligaments, or PDL.
BACKGROUND
Teeth generally comprise an upper exposed portion, or crown, which is visible
and an
underlying root structure which is hidden, being anchored within the bony
substructure of the
gums. The interface between the root structure of the tooth and the
surrounding bone is a
fibrous attachment. These fibers are referred to as the periodontal ligaments
or PDL. The space
occupied by the periodontal ligaments is known as the PDL space, and averages
about .25 mm
in thickness and surrounds the entire root structure of the tooth.
It is often necessary to separate the ligamental attachment during various
surgical procedures.
Such procedures include the extraction of teeth, and the installation of
dental implants and
common surgery to remove roots broken during extraction or through trauma.
While extraction
is one of the most common dental procedures it is fraught with difficulty. The
great forces
employed to dislodge teeth from bone are difficult to control and so, have
unpredictable
outcomes.
One of the main obstacles in the removal of teeth is to overcome the
resistance of the PDL. The
most common method used to overcome this resistance is bucco-lingual luxation,
which
expands the socket by loosening of the tooth by grasping with forceps and
rocking the tooth in
all directions in order to compress the proximate, relatively spongy portion
of the surrounding
bone, and stretch the periodontal ligaments until they break. Great force is
needed to
accomplish this, and the frequent result is fracture of the tooth or fracture
of the surrounding
bone that forms the buccal plate. Both of these problems lead to further
surgical complications.
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In the case of a fractured crown, it is often necessary to resort to a full-
surgical extraction,
elevating the soft tissue and removing bone, in order to gain access to the
retained root. Full
surgical procedures are time-consuming, traumatic to the patient, and carry
more risk of
infection and healing complications. In the case of a fractured buccal plate,
the bone loses its
blood supply, and will resorb away. Soft tissues will epithelialize faster
than the bone will
regenerate, and the remaining portion of the gum which formerly supported the
tooth, also
known as the ridge, will display a depression or defect. Loss of the bony
architecture and its
replacement by soft tissues, further complicates the prosthetic treatment
plan. Indeed, in such a
scenario, it is likely that a bone graft will be required. In other words,
conventional crown and
bridge prosthesis require bony suppol-t, and replacement of the tooth with an
implant requires
healthy surrounding bone. Often, it is necessary to do a separate preliminary
surgery (Guided
Bone Regeneration) to repair a defect before an implant is placed.
While instruments capable of cutting the PDL are known to be used in
connection with the
extraction of teeth, such instruments fail to have the range and configuration
necessary to
effectively perform this function. In addition, such prior art instruments are
clumsy to work
with and have limited functionality in connection with such cutting, because
they are often too
thick, or improperly angled.
SUMMARY OF THE INVENTION
It is an object of the invention to remedy the deficiencies of the prior art
heretofore discussed.
It is a further object of the invention to provide an instrument which allows
the separation of the
ligamental attachment without destroying the buccal plate.
It is a further object of the invention to provide an instrument with two
functional tools which
function synergistically to allow the user to separate the ligamental
attachment and allow teeth
to escape the bone occlusally.
It is a further object of the 111Ve11t1011 to provide a method which allows
the separation of the
ligamental attachment while minimizing damage to the buccal plate.
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The invention is directed to a dental instrument. namely a periotome: The
inventive instrument
is of particular value because it comprises a handle having two tools. The
handle is preferably
made of hollow stainless steel, aluminum alloy or other lightweight material
which makes it
comfortable and easy to control. At one end there is a tool with a thin,
flexible, angled blade for
insertion to separate the gingival attachment and enter the PDL space. The
angulation and
length are suited to circumscribe the entire circumference of the root
structure, all the way to the
root apices.
At the other end of the inventive periotome there is a second tool which
comprises a larger,
spatula-shaped member tapering into a triangular tipped blade having a size
and thickness
adapted to create space for the introduction of extraction instruments in a
controlled manner,
after cutting out the PDL, and at locations dictated by the surgeon. The
preservation of bone
eliminates the need for follow-up repair of the ridge, simplifying the
prosthetic treatment plan.
In other words, the invention addresses the inefficiency of destroying the
fibrous attachment by
tearing apart the periodontal ligaments. Rather, in accordance with the
invention, the ligaments
are incised, with substantially no trauma to the surrounding bone.
In another aspect, the invention provides a motorized dental instrument
comprising: a support
member; a dental tool, said dental tool extending from said support member and
being seated
in said support member such that the dental tool is capable of linear motion;
and, at least one
mechanical link between the motor and said dental tool in said support member,
whereby the
dental tool is driven in reciprocating motion.
In a further aspect, the invention provides a motorized dental instrument,
comprising: a support
member; a dental tool, said dental tool extending from said support member and
being seated
in said support member such that the dental tool is capable of linear motion;
a tappet seated in
said support member, said tappet contacting said tool, whereby said contact
extends said tool
outward from said support member; at least one shaft rotatably seated in said
support member,
whereby said shaft is driven by said motor; and a cam coupled to said shaft,
said shaft
contacting said tappet.
In a still further aspect the invention provides a motorized dental instrument
comprising: a support member; a dental tool, said dental tool extending from
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said support member and being seated in said support member such that the
dental tool is capable of motion in a closed loop path; and, at least one
mechanical link between the motor and said dental tool in said support
member, whereby the dental tool is driven in reciprocating motion.
BRIEF DESCRIPTION OF THE DRAWINGS
Some embodiments of the invention will now be described in detail, by way of
example, with reference to the accompanying drawings in which:
Figure 1 is a side elevational view of a preferred embodiment of the
invention;
Figure 2 is a detailed side view of a portion of the instrument shown in
Figure 1
showing the first tool;
Figure 3 is a detailed perspective view of a portion of the instrument shown
in
Figure 1 showing the first tool;
Figure 4 is a detailed side elevational view of a portion of the instrument
shown
in Figure 1 showing the second tool;
Figure 5 is a detailed view along lines 5-5 of Figure 4 showing other aspects
of
the configuration of the second tool;
Figure 6 is a detailed side view of the embodiment shown in Figure 1 showing
part of the handle;
Figure 7 is a front view of a portion of the instrument shown in Figure 1
showing a second embodiment of the first tool;
Figure 8 is a side view of Figure 7 across lines 8-8;
Figure 9 is a side view of Figure 7 across lines 9-9;
Figure 10 is a side view of Figure 7 across lines 10-10;
Figure 11 is a front view of a portion of another embodiment of the inventive
periotome;
Figure 12 is a side view of Figure 7 across lines 12-12;
Figure 13 is a front view of a portion of the instrument shown in Figure 1
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showing another embodiment of the first tool;
Figure 14 is a side view of Figure 13 across lines 14-14;
Figure 15 is a front view of a portion of the instrument shown in Figure 11
showing another embodiment of the first tool;
Figure 16 is a side view of Figure 15 across lines 16-16;
Figure 17 is a perspective view of the scalpel or incisor tip being inserted
into
the PDL space on the buccal aspect of a maxillary right first molar;
Figure 18 is a perspective view of the separator blade of the present
invention
being inserted into the PDL space on the mesial aspect of the same tooth;
Figure 19 shows typical anatomy of a maxillary right first molar, surrounding
bone and soft tissues, as viewed from the mesial aspect;
Figure 20 is and exploded side view of a powered periotome constructed in
accordance with the present invention;
Figure 21 is a view of the blade of the powered periotome of Figure 20;
Figure 22 is a side view of a powered periotome constructed in accordance with
the present invention;
Figure 23 is a plan view of a track member useful for converting rotary motion
to angularly fixed circumferential motion;
Figure 24 is a view along lines 24-24 of Figure 23 showing the depth of the
tracks in the track member;
Figure 25 is a view along lines 25-25 of Figure 23, showing of the structure
of the
track member in cross-section;
Figure 26 is a view along lines 26-26 of Figure 24, showing the back of the
track
member;
Figure 27 is a plan view of a follower member useful in accordance with the
method of the present invention;
Figure 28 is a view along lines 20 a-20 a a Figure 27 showing a view of the
follower member from the side;
Figure 29 is a detail along lines 29-29 of Figure 28, showing a bottom plan
view
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of the follower member of Figure 27;
Figures 30-35 are schematic diagrams illustrating the function of the track
and
follower in achieving the desired angularly fixed, circumferential movement in
the powered periotome blade of the invention;
Figure 36 is a detailed schematic of the preferred embodiment of the power
periotome.
Figure 37 is a cross section view of the compression band in the lower housing
illustrated in Figure 36 viewed along lines 37-37.
Figure 38 is a cross section view of the ball bearing sleeve illustrated in
Figure
36 viewed along lines 38-38.
Figure 39 is a detailed cross section view of the head housing illustrated in
Figure 36 viewed along lines 39-39.
Figure 40 is a schematic side view of the head housing illustrating the
retainer
clip viewed along lines 40-40.
Figure 41 is a top view of an alternative tip embodiment.
Figure 42 is a side view of the tip in figure 41 viewed along lines 42-42.
Figure 43 is a detailed cross section view of the head housing similar to that
of
Figure 39 illustrating an alternative tip embodiment.
Figure 44 is a schematic side view of the head housing illustrated in Figure
43
viewed along lines 44-44.
Figure 45 is a top view of an alternative tip embodiment similar to that
illustrated in Figure 39 with the head of the tip laterally flexed to the
left.
Figure 46 is a side view of the tip in Figure 45 viewed along lines 46-46.
Figure 47 is a top view of an alternative tip embodiment similar to Figure 45,
except with the head of the tip laterally flexed to tile right.
Figure 48 is a side view of the tip illustrated in Figure 47 viewed along line
48-
48.
Figure 49 is a top view of an alternative tip embodiment.
Figure 50 is a side view of the tip illustrated in Figure 49 viewed along line
50-
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50.
Figure 51 is a detailed schematic of the preferred embodiment of the power
periotome with an alternative tip embodiment.
Figure 52 is a side view of the tip illustrated in Figure 51 viewed along line
52-
52.
Figure 53 is a detailed schematic of the preferred embodiment of the power
periotome similar to the one illustrated in Figure 36 with the addition of
rases to
reduce vibration.
Figure 54 is a detailed schematic of the preferred embodiment of the power
periotome similar to the one illustrated in Figure 36 with an increase in the
angle between the upper housing member and lower housing member.
Figure 55 is a detailed schematic of the preferred embodiment of the power
periotome similar to the one illustrated in Figure 54 with the addition of
rases to
reduce vibration.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Figure 1 shows a preferred embodiment of the inventive periotome 10.
Periotome 10 comprises a handle 12 with two functional tools 14 and 16 secured
at each of its ends. In preferred embodiments, the cutting surfaces of the
tools
are coated with titanium nitride so that the blades remain sharp.
As seen most clearly from Figure 2, tool 14 preferably comprises three
sections,
a base 18, a stem 20, and a blade 22. Base 18, stem 20 and blade 22 are all
formed from a single piece of metal. Base 18, stem 20 and blade 22 are
connected at angles, preferably with rounded corners for safety. The
angulation
and length of the sections of tool 14 are suited to circumscribe the entire
circumference of the root structure, all the way to the root apices.
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Base 18 is formed as a roughly frustro conical member which tapers into stem
20. The length of base 18 is between 5 -15 mm, preferably 10 mm. Its larger
diameter adjacent handle 12 is 2.54 mm. Stem 20 is set at an angle of between
120-170 degrees, preferably 140 degrees in one direction from base 18. Stem 20
is formed as a continuing frustro conical member which tapers into blade 22.
The length of stem 20 is between 5 -15 mm, preferably about 8.9 mm while the
larger diameter is between 1 - 2 mm, preferably about 1.5 mm. Blade 22 is set
at
an angle of between 20 and 45 preferably 39 degrees in the opposite direction
with respect to stem 20. The sharp angle allows the user to get into a smaller
area without hitting other teeth. Blade 22 is formed with a substantially
rectangular shape and is flat with a thickness of about .46 mm, and a width of
about 1.8 mm. Blade 22 preferably comprises a continuous cutting edge defined
by five cutting surfaces 24, 26, 28, 30, and 32 as shown in Figures 2 and 3.
Surfaces 24 and 32 are used to cut in the mesio-distal direction. Surface 28
is
used to cut in the apical direction. Surfaces 26 and 30 are rounded points
which
can be used to cut in the apical direction.
As shown in Figure 4, tool 16 is formed from a member 34 which first tapers
inwardly then outwardly into a spatula-shaped blade 36. In accordance with
the preferred embodiment illustrated in Figure 1, tool 16 has a length of
about
25.4 mm. Member 34 has a thickness at point 31 of between 2 - 6 mm, preferably
3.30 mm in the direction of the plane of the drawing. It then tapers inwardly
to
a thickness of between 0.5 - 2.5 mm, preferably 1.9 mm at point 33 in the
direction of the plane of the dr awing of Figure 4. Member 34 then flattens
and
expands to a width of between 2 - 6 mm, preferably 2.54 mm in the direction of
the plane of the drawing. Member 34 preferably has a circular cross section
point 31 and point 33.
Figure 5 shows a side view of triangular tipped blade 36. Blade 36 is of a
size
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and thickness so that the surgeon creates enough space for the introduction of
extraction instruments in a controlled manner, and at locations dictated by
the
surgeon. More particularly, at point 35, the blade has a thickness on the
order of
between 1 - 3 mm, preferably 1.3 mm in the direction of the plane of the
drawing of Figure 5. From there it terminates in a point. Blade 36 is
preferably
triangular in shape with three cutting surfaces, 38, 40, and 42. The length of
blade 36 is about 37.4 mm. The angle of the tip is about 40 degrees.
Handle 12 is preferably made of hollow stainless steel. It is preferably
lightweight, weighing about between 0.2 oz. - 2.0 oz., preferably 0.8 oz.
These
parameters make handle 12 comfortable and easy to control. Handle 12
preferably comprises a center section 44 and two roughly frustro conical end
sections 46 and 48. Center section 44 comprises a hollow tube which is formed
for comfort to the user. In preferred embodiments, the tube has a triangular
or
hexagonal cross section so that the tool rests comfortably between the
fingers.
The length of center section 44 is between 60 -120 mm, preferably 90 mm.
Center section 44 has a diameter which is between 5 - 30 mm, preferably 11 mm.
In preferred embodiments, center section 44 also comprises a plurality of
support indentations or ridges 50 placed at points approximately 1/4 and 3/4
of
the length of center section 44. The dimensions of the handle are balanced to
reduce hand fatigue (where a larger diameter is preferred) with functionality
as
a dental instrument (where a smaller diameter is preferred). The larger
diameter is available due to the angulation of tool 14 as the provision of at
least
three cutting surfaces on the tool to allow greater flexibility in smaller
spaces as
well the use of frustro conical tapered end sections 46 and 48.
Figure 7 shows a second preferred embodiment of the inventive periotome 110
which is similar in configuration to periotome 10. Base 118 is formed as a
roughly frustro conical member which tapers into stem 120. The length 150 of
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base 118 is between 7 and 10 mm, preferably 8.6 mm. Diameter 152 is about 1.9
mm. Stem 120 is set at an angle 154 of about 20 degrees, from base 118. Stem
120 is formed as a continuing frustro conical member which tapers into blade
122. The length of stem 120 is preferably 16 mm while the larger diameter 155
is about 1.4 mm as shown in Figure 9 which is a side view taken across lines 9-
9
of Figure 7. The vertical distance 156 from the top of stem 120 to the bottom
of
base 118 is about 17.35 mm. Blade 122 is set at an angle 158 of about 39
degrees
from base 118 in the opposite direction. A side view of blade 122 across lines
8-8
is shown in Figure 8. The length 160 of blade 128 is about 1.88 mm. The
vertical
distance 162 of blade 122 to base 112 is about 30 mm. The thickness 164 of
blade
122 is about 5.3 mm. The shape between cutting surfaces 126 and 128 is a
radius
of about .031 inches. Figure 10 is a side view across lines 10-10.
Figure 11 shows another embodiment of the inventive periotome. Periotome
210 is similar in configuration to periotomes 10 and 110. However, blade 222
is
now rotated between 20 to 80 degrees, ideally between 37 and 52 degrees,
preferably about 45 degrees. The rotated blade allows the surgeon to come in
from the fr ont of the mouth and reach, for example, the interior portion of
the
back molars. Figure 12 is a side view across lines 12-12. Without the
angulation
it is difficult for the surgeon to cut straight down into the gum line to
separate
the tooth because the cheek is in the way.
Figure 13 shows a fourth preferred embodiment of the inventive periotome 310
which is similar in configuration to periotome 110. However, the angulation
350
of blade 322 from stems 319 and 320 is deeper. Figure 14 is a side view taken
along lines 14-14.
Figure 15 shows a fifth embodiment of the inventive periotome 410 which is
similar in configuration to periotome 310 with blade 422 rotated between 20 to
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80 degrees, ideally between 37 and 52 degrees, preferably about 45 degrees.
Figure 15 is a side view taken along lines 15-15.
Although the above periotomes have been shown having a spatula shaped
blade on one end, it is also contemplated that there may a surgical kit which
comprises a periotome similar to that shown in Figure 1 and a second periotome
which comprises two angular blades similar to the blade shown in Figure 11 but
instead of having a spatula shaped tool on the second end, there may be
instead
a tool which is a mirror image of the
first tool on the second end. It is also contemplated that the kit may
comprise a
handle with two ends and four tools mountable on at least one of the ends so
that a surgeon would have all the tools necessary for cutting into the PDL
space.
In practice, the surgeon will use tool 14 to come in from the occlusal
direction
and cut into the PDL space about 12 mm or so. The five cutting surfaces 24,
26,
28, 30, and 32 and flexibility of blade 22 allows the surgeon to come in from
the
side without hitting the jaw. Then the surgeon will gently insert triangular
tipped blade 36 of tool 16 into the space made with tool 14. Then the surgeon
will rock blade 36 back and forth so that cutting surfaces 38, 40, and 42 will
gently expand the ridge of the socket with minimal compression to the bone
without damaging the bone until there is enough space for the introduction of
extraction instruments in a controlled manner, and at locations dictated by
the
surgeon. Normally, anatomy, i.e., proximity of other teeth, etc. dictates
where
elevators and forceps are applied. Here the site of application is formed by
blade 36 where the surgeon can take advantage of greater bone mass. It is
noted
that the working tips of the instrument of the present invention are made of
stainless steel. After being forged, the same are heat treated and sharpened.
After being heat treated, tool 16 is formed into a specialized wedge to work
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an adjunct to the cutting tip 14.
As can be seen in Figure 13, the proper orientation of cutting tip 14 is
substantially parallel to the axis of the tooth, allowing it to be advanced in
the
direction off the axis of the tooth into the periodontal ligament space on the
buccal aspect of a maxillary right first molar. After tip 14 has been inserted
into
the space, it is carefully worked along the service on the tooth to create a
space
to allow tip 16 to be inserted as shown in Figure 14. This is better
understood
with reference to Figure 15 which shows typical anatomy of a maxillary right
first molar, and surrounding bone and soft tissues, as viewed from the mesial
aspect in cross-section. This anatomy includes the maxillary right first molar
71,
the periodontal ligaments 73 completely surrounding the root structure and
attaching it to bone, the cortical bone plate 75, and the gingival soft
tissues 77.
During use on the subject instrument, the objective is to cut as much of the
periodontal ligaments 73 as possible, in order to treated to a more removal
without destruction often be soft bone 79.
In accordance with a particularly preferred embodiment of the invention,
structure is provided for increasing speed and control during the surgery.
More
particularly, when the periotome is being used to cut and separate tissue,
careful angular and positional control of the cutting blade must be maintained
while applying substantial force. Substantial improvement in use of the
periotome is provided by the embodiment of the invention illustrated in
Figures
20-35. More particularly, in accor dance with this embodiment of the
invention,
the periotome incorporates a powered blade. Like the periotome illustrated in
the previously described embodiment of the invention, the blade in the
inventive powered periotome 410 illustrated schematically in Figure 20 is
substantially flat and exceedingly thin. Thus, the blade 422 generally lies in
a
plane perpendicular to the plane of the paper in Figure 20.
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In accordance with this embodiment of the invention, the blade is powered to
have movement substantially only within the plane defined by the blade 422. In
other words, referring to Figure 21, which illustrates the blade 422 of the
periotome illustrated in Figure 20, during powered movement of the blade, the
cutting edges 424, 426, 428, 430 and 432 all move in one plane. Moreover, such
movement is de minimis. However, such movement occurs very rapidly. For
example, such movement may consist of elliptical or circular movement with
sixty elliptical cycles occurring every second. The result is not to cut
substantial
amounts of tissue in any one cycle of the movement of the blade 422, but
merely
to make movement of the periotome relatively effortless and limited to guiding
the cutting of the tissue by the powered scalpel cutting edge surfaces.
It is noted that if such movement is not in a plane, the result will be a flat
periotome blade which has a cutting surface moving not only in the direction
in
which one wishes to cut tissue, but also moving with a component orthogonal to
the desired direction of cutting, which can result in otherwise avoidable
damage
to tissues during the surgery.
In accordance with the invention, it is contemplated that movement of the
periotome blade may be in one of three possible general modes.
In the first mode, such movement is in the plane of the blade of the periotome
but only with a component perpendicular to small cutting surface 428 in Figure
21. In this mode, the periotome is used in the powered mode strictly in a
movement which involves insertion of the blade into and along the contour,
which one wishes to cut, in the direction perpendicular to small cutting edge
428. As can be seen from the figures, cutting of tissue in the direction
perpendicular to elongated cutting surfaces 424 and 432 in Figure will only be
achieved in such mode in response to the manual application of force by the
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surgeon.
In the second mode, such movement is also in the plane of the blade of the
periotome but only with a component perpendicular to the elongated cutting
surfaces 424 and 432 in Figure 21. In this mode, the periotome is used in the
powered mode strictly in a movement in the direction perpendicular to
elongated cutting edges 424 and 432. As can be seen from the figures, cutting
of
tissue in the direction perpendicular to the small cutting surface 428 in
Figure 21
will only be achieved in such mode only in response to the manual application
of force by the surgeon.
In the third mode, such movement is again in the plane of the blade of the
periotome but with both a component perpendicular to the elongated cutting
edges 432 and 424, with a component perpendicular to small cutting edge 428
and with a component perpendicular to the rounded corner cutting edges 426
and 430. In this mode, the periotome is used in a very versatile movement
which involves both insertion of the blade into and along the contour which
one
wishes to cut, in any direction, with the blade being moved to define the
surface
along which one wishes to cut. Moreover, such movement is achieved in such
mode without the manual application of substantial force by the surgeon.
Referring to Figures 20 and 22, the operation of the powered periotome may be
understood. A motor, not illustrated, is coupled to a flexible drive member
450
which, in turn, the secured to a drive stub 452 on a drive wheel 454. Drive
wheel 454 includes a bore 456 position at a distance from the center of
rotation
of drive wheel 454. Drive wheel 454 is mounted for rotation in a bore 463 on a
block 458. Block 458 is secured to and formed integral with the outer casing
460
of powered periotome 410.
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Drive wheel 454 is, in turn, coupled to follower 462 which includes a follower
pin 464 which is positioned within and mates with bore 456 in such a way that
surface 466 bears against and slides against surface 468 when rotary drive is
applied to flexible drive member 450.
Follower 462, in turn, rides within track member 470, which is illustrated in
Figures 23-26. Track member 470 includes a pair of circular tracks 472-474.
Tracks 472 and 474 mate with and receive follower pins 476 and 478. Track
member 470 is secured in position within casing 460 as illustrated in Figure
22
by glue. Alternatively, track member 470 may be formed integrally with casing
460.
When force is applied in the direction indicated by arrow 480 in Figure 22,
flexible drive member 450 rotates, resulting in rotation of drive wheel 454.
This
1 S causes bore 456 to follow a circular path 482 displaced by a radius from
the
center of rotation of drive wheel 454. Because follower pins 476 and 478 are
contained within circular tracks 472 and 474 engraved within track member 470,
the result is that follower 462 maintains its angular position while moving
along
a circular path. This can be understood with reference to Figures 30 through
35.
As illustrated in Figure 22, blade 422 is contained within a plane parallel to
the
plane which contains follower 462. Accordingly, because blade 422 is secured
by shank 484 to a base 486 which is secured to follower member 462, as
follower
462 moves, blade 422 also moves, but remains in one plane, thus achieving the
desired cutting motion. More particularly, as rotary torque is applied to
flexible
drive member 450, a circular cutting motion is imparted to blade 422, while
maintaining blade 422 in a single plane, thus achieving the operation defined
as
the third mode of movement above.
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Such motion may be more clearly understood with reference to Figures 30
through 35. In particular, as follower 462 is moved, the result is that the
base
486 is caused to move along a circular path 490, while maintaining a fixed
angular orientation. More particularly, base 46, and blade 422 attached to it
will
in a circular path which is at the two o'clock position as illustrated in
Figure 30,
the four o'clock position as illustrated in Figure 31, the five o'clock
position as
illustrated in Figure 32, the six o'clock position as illustrated in Figure
33, the
nine o'clock position as illushated in Figure 34, and finally the 11 o'clock
position as illustrated ll1 Figure 35.
Figure 36 illustrates inventive power periotome 810. Power periotome 810
comprises a housing 811. Housing 811 comprises a lower housing member 812
Lower housing member 812 attaches to a conventional power source 809,
illustrated in phantom lines at an end 812a and an angled housing member 814
at an opposite end 812b of lower housing member 812. Serrations 808 are
engraved in eight bands on outer surface 813 of lower housing member 812 to
minimize slippage when power periotome 810 is being gripped by an operator
Lower housing member 812 has a length of 33 millimeters and a diameter of ten
millimeters. Contained within lower housing member 812 is a lower rotating
rod 816. Lower rotating rod 816 has a height of 45 millimeters and a diameter
of
two millimeters and terminates within angled housing member 814 as a ten
toothed crown gear 818. Gear 818 is three millimeters in height and five
millimeters in diameter. Proximal end 815 of lower rotating rod 816 attaches
to
conventional power source 809. Gear 818 is mounted on distal end 817 of lower
rotating rod 816. Gear 818 is housed in angled housing member 814. Gear 818
couples to a mating crown gear 822 which is secured to an upper rotating rod
820. A compression band 824 is attached to lower rotating rod 816 at a point
30
millimeters from proximal end 815 of lower rotating rod 816. Compression
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band 824 is one millimeter in thickness and two millimeters in height.
Compression band 824 is compression fitted against lower rotating rod 816 and
configured so as to prevent lower rotating rod 816 from slipping out of a ball
bearing sleeve 826, as is illustrated in cross section in Figure 37.
In connection with this invention, it is noted that all dimensions given are
approximate and be widely varied.
Just distal to compression band 824 is a ball bearing sleeve 826. Ball bearing
sleeve 826 is thirteen millimeters in length; proximal end annular ridge 826a
is
one millimeter in height and six millimeters in diameter and configured to
rest
against compression band 824, moving distally the next half millimeter is an
indentation 826b with a five millimeter diameter, the next distal two
millimeters
have longitudinal serrations 826c with an outside diameter of six millimeters.
Longitudinal serrations 826c are so configured and dimensioned to be friction
fitted with lower housing member 812, as is illustrated in cross section in
Figure
38. The next distal three and one half millimeters are smooth as indicated at
area 826d with a diameter of six millimeters, the next distal one millimeter
is
indented as indicated at 826e to a diameter of five millimeters, terminating
distally in a threaded region 826f of five millimeters in length and six
millimeters in diameter. Threaded region 826f rests against a proximal surface
818a of gear 818. Threaded region 826f of ball bearing sleeve 826 provides a
threaded attachment for lower housing member 812 with angled housing
member 814.
Angled housing member 814 is bent at a seventeen degree angle rearwar d from
a front (blade) surface 814a. A lower section 814b of angled housing member
814 is eight millimeters. Long Upper section 8144 of angled housing member
814 is about seven millimeters. The intermeshing of gears 818 and gear 822
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translates the rotation provided by conventional power source 809 to lower
rotating rod 816 to upper rotating rod 820. Angled housing member 814
threadedly engages 825 upper housing member 828.
Upper housing member 828 contains upper rotating rod 820. Upper rotating
rod 820 consists of mating gear 822 at a proximal end 821. Mating gear 822 is
a
ten toothed crown gear of three millimeters height and five millimeters
diameter. A distal end 823 of upper rotating rod 820 has a cam base section
830,
one millimeter in height and five millimeters in diameter, and a cam section
832
which is five millimeters in height and a two millimeter sided square with
rounded edges. Upper housing member 828 engages a head housing member
834 via threads 829.
As demonstrated in Figure 39 in a top view cross section, head housing member
834 contains cam section 832, cam follower 836, a blade coupling member 838,
and a blade base post 840. Cam follower 836 contains a rear section 836a one
millimeter thick and five millimeters in diameter, an arm section 836b, Arm
section 836b connects rear section 836a with a fr ont section 836c. Arm
section
836b is three millimeters long and two jnillimeters thick, front section 836c
is
five millimeters long and five millimeters in diameter. Front section 836c is
a
hollow. As cam section 832 rotates to the position illustrated in phantom
lines,
cam follower 836 reciprocates within head housing member 834, with cam
follower 836 moving posteriorly to dotted line 852 in response to applied
pressure in the direction of 850 from a tooth being operated on.
Contained within hollow 836d of front section 836c is blade coupling member
838. Blade coupling member 838 has a hollow 838a to receive blade 848. Blade
base post 840 is within hollow 838a of blade coupling member 838. Blade base
post 840 is four millimeters in length and two millimeters in diameter. Blade
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ridge 842 fits into an anterior hollow 834a of head housing member 834.
Retainer clip 846 secures blade 848 in position.
A retainer section 846a of retainer clip 84G is configured and dimensioned to
match the anterior aspect of head housing member 834 with a one and one half
millimeters section hollowed out in the center of the anterior aspect and a
section in the top one and one half millimeters removed to allow for retainer
clip 846 to be slipped in front of head housing member 834. The thickness of
retainer clip 846 is three-tenths of a millimeter. An arm section 846b of
retainer
clip 846 travels posteriorly six millimeters to join with clip section 846c.
Clip
section 846c has a height of ten millimeters and sits on the anterior two-
thirds of
upper housing member 828, configured and dimensioned to approximate the
diameter of the anterior two-thirds of upper housing member 828.
The preferred embodiment contains a straight blade 848 which is 30 millimeters
in length, with a height tapering from three millimeters at blade ridge 842 to
two
millimeters at a point 20 millimeters from blade ridge 842 and then sustains
the
two millimeter height until a termination 848a. The distal end of blade 848 is
rounded with a two millimeter width. The top view in Figure 39 shows blade
848 tapering from three millimeters to one millimeter at a point 20
millimeters
from blade ridge 842 and maintaining the one millimeter width through
termination 848a. The distal ten millimeters of blade 848 has the superior,
distal, and inferior surface honed to a sharp edges.
When it is desired to operate the inventive power periotome 810, the dentist
or
his assistant grabs the device after attaching it to a source of power 816
which is
presently available in the offices of many dentist. When the power source is
activated, rod 816 rotates, this results in rotating part 826. Because crown
gear
817 is integral with part 826, mating crown gear 822 is caused to rotate.
Result
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is that cam portion 832, which is rigidly secured to mating crown gear 822 is
also caused to rotate. When the dentist presses blade 842 in position to sever
the
periodontal ligament, pressure is applied against blade 842 in the direction
indicated by arrow 850 in figure 39. As cam portion 832 rotates, follower 836
is
driven by the pressure in the direction of arrow 850 as cam 832 is driven from
the position shown in solid lines in figure 39 to the position shown in
phantom
lines in figure 39. As cam 32 continues to rotate from the position shown in
phantom lines to the position shown in solid lines, it drives follower surface
836
in the direction opposite the arrow 850 and thus imparting a reciprocating
motion to blade 848.
Figures 41- 44 illustrate an alternative tip embodiment. Corresponding parts
have numbers 100 greater than corresponding parts in the embodiment
illustrated in Figures 36 - 40. Figure 43 shows a tip 944 within head housing
member 934. Tip 944 is different from tip 844 by the use of an angled blade
configuration. In particular, blade 948 is 27 millimeters in length with
tapering
from three millimeters at ridge 942 to one millimeter at a point seventeen
millimeters from base ring 942. The distal ten millimeters of blade 948
maintains the one millimeter width with the superior, distal, and inferior
surface honed to sharp edges. In Figure 42 and 44 it can be seen that blade
948
projects straight at portion 941 from base ring 942 a distance of ten
millimeters,
tapering from a height of three millimeters to two and one half millimeters.
Blade 948 then takes a 25 degree superior turn 943 and extends for ten
millimeters, further tapering from two and one half millimeters to two
millimeters. Blade 948 then takes a 65 degree inferior turn 945 and extends
for
another ten millimeters, terminating with a two millimeter height rounded off
at
the tip.
Figures 45-48 illustrate a variation of the previous tip. Tip 1044 is similar
to tip
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944 except that the distal ten millimeters section is angled 45 degrees to the
left
at point 1047 in Figure 45.
Tip 1144 is similar to tip 1044 except that the angle at point 1147 is to the
right
(Figure 47).
The Figure 45 and Figure 47 tips allow the user to hug the surface of the
tooth
and root whether right or left, upper or lower.
Figures 49 and 50 illustrate another alternative tip embodiment. Blade base
post
1240 is four millimeters in length and two millimeters in diameter. Blade
ridge
1242 is one millimeter in length and three millimeters in diameter. In side
view,
as illustrated in figure 49, blade 1248 projects distally 38 millimeters. At
blade
ridge 1242 the diameter of blade 1248 is three millimeters and tapers to two
millimeters at a point 1241 ten millimeters from blade ridge 1242, for the
next
distal twenty millimeters blade 1248 widens 1243 to three millimeters with the
terminal eight millimeters tapering to a point 1245. The top view illustrated
in
Figure 50 shows at blade ridge 1242 the diameter of blade 1248 three
millimeters
and tapers to two millimeters at a point ten millimeters from blade ridge
1242,
in the next distal ten millimeters blade 1248 widens to three millimeters and
the
terminal 18 millimeters tapers to a point.
Figures 51 and 52 illustrate another alternative tip embodiment. Blade base
post
1340 is four millimeters in length and two millimeters in diameter. Blade
ridge
1332 is one millimeter in length and three millimeters in diameter. Distal to
blade ridge 1342 shaight blade 1348 which is 30 millimeters in length, angles
superiorly 40 degrees at a point 1343 twenty millimeters from blade ridge 1342
to approximate the angle of the non-powered handtool currently in use. Blade
1348 has a length of 30 millimeters from blade ridge 1332 Tlle present
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embodiment has a height of three millimeters from blade ridge 842 to its
termination. Distal end 1349 of blade 1348 height is rounded with a two
millimeters width. The top view of tip 1344 only (Figure 52) shows blade 1348
tapering from three millimeters to one millimeter at 20 millimeters from blade
ridge 1342 and maintaining the one millimeter width through the termination of
blade 1348. The distal ten millimeters of blade 1348 has the superior, distal,
and
inferior surface honed to sharp edges.
Figure 53 shows another alternative embodiment of inventive power periotome
1410. Contained within lower housing member 1412 is lower proximal race
1452 and lower distal race 1454. These races are positioned against a inside
surface 1412a of lower housing member 1412 and lower rotating rod 1416, they
are designed to snap into a groove in the inside wall of lower housing member
1412. The purpose of these races is to minimize vibration of lower rotating
rod
1416. Contained within upper housing member 1428 is upper proximal race
1456 and upper distal race 1458. These races are positioned against inside .
surface 1428a of upper housing member 1428, and snap into a groove in inside
surface 1428a. The purpose of these races is to minimize vibration of upper
rotating rod 1420. The four races work collectively to reduce the vibration of
power periotome 1410. In recent years there have been a lot of ergonomic
research into the nerve damaging effects of repetitive vibrations, including
loss
of sensation in the pacinian corpuscles, meissner's corpuscles, and pain
receptors; as well as damage to the microvasculature. The implementation of
these races, by reducing vibration in power periotome 1410, helps to prevent
such injury.
Figure 54 illustrates another alternative embodiment of inventive power
periotome 1510. Angled housing member 1514 positions lower housing
member 1512 and upper housing member 1528 at a forty degree angle. This
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places blade 1548 at the relative angle to lower housing member 1512 of fifty
degrees approximating the angle of the non-powered handtool currently in use.
Thus giving the user the familiar feel and control he is accustomed to.
Figure 55 illustrates an alternative embodiment of inventive power periotome
1610. When angled housing 1611 is combined with lower proximal race 1652
and lower distal race 1654 upper proximal race 1656 and upper distal race 1658
to reduce the vibration as described above, this further increases the comfort
and control to the user.
While some illustrative embodiments of the invention have been described
above, it is, of course, understood that various modifications will be
apparent to
those of ordinary skill in the art. Such modifications are within the spirit
and
scope of the invention, which is limited and defined only by the appended
claims.
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