COMPLETE DIBUITICATION
Year: 1887

page_text: The decision of the Comptroller-General, of the 23rd day of July 1892, allowed,
under Section 18 of the Patents, &c. Act, 1883, an Amendment of this
Specification.
COMPLETE DIBUITICATION
Improvements in Dentists' Burring Tools.
I, SYDNEY PITT of Sutton in the County of Surrey Gentleman (a communication
to me from abroad by Arthur W. Browne, a Citizen of the United States, of Prince's
Bay, in the County of Richmond and State of New York) do hereby declare the
nature of this invention and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement:―
My invention relates to excavating or cavity burrs more especially designed for
dentists use.
Excavating or cavity burrs as made for dentists' use, are intended to cut their way
into the tooth substance, whether advanced after the manner of a drill, in the direction
of their axis of rotation, or at an angle to this axis. They are made in a variety of
As a
forms and sizes to facilitate the excavating of all shapes and sizes of cavities.
large part of the cutting these tools are used for is done in sensitive dentine, it is
extremely desirable that they be constructed to do the work with the least possible
pain to the patient. To accomplish this result, the burrs must cut freely without the
necessity of crowding them forward to their work and must free themselves constantly
from chips as in many cases when cutting in close proximity to a nerve the least
pressure or heat becomes almost unbearable. It is a fact that the old form of burrs
heretofore in use will cut with much less pressure and more freely when advanced in
a line at right angles to the axis of rotation than when advanced in the line of its
axis. Several reasons may be given for this.
First. The teeth or leaves of the burr all coming together at the end of the axis
there is no cutting-edge at this point. In fact it has usually been the practice to put
a small cut across the extreme end of the burr in which case in using the end of the
burrs there is a small projection of the material operated in, which cannot be cut by
the burr, and which must break away in order to allow the tool to advance.

page_text: Second. In advancing the burr in the line of its axis every tooth or leaf-and
there are usually eight-will be constantly cutting-while of advanced at right
angles to its axis two, or at most three teeth are all that can be brought into action
at arry one time. It of course requires four times as much pressure to make eight
cutting edges of a given length penetrate the materials as would be necessary to
make two teeth of the same length take a like cut.
Third. It is a fact that in the old form of burr the spaces between the teeth or
leaves near the end of the axis of the burr are much narrower and the cuts shallower
than at any other portion, so that there is little room for chips, and it is found in
practice that the chips do not get away from the cutting edge freely enough to
prevent the spaces from choking, when of course there is great beat developed from
the resulting friction and very little cutting is accomplished.
The object of my present invention is to provide an improved burring tool in
which the objections to and imperfections in the old style of burr noted above will be
avoided.
The improvements will first be described with the aid of the accompanying
drawings sufficiently in detail to enable them to be clearly understood. I will then
distinctly recite the subject matter claimed herein as my invention at the close of this
specification.
In said drawings Figure 1 is a view of my improved burring tool with the shank
thereof having a flattened transversely-grooved driving end to adapt it to the rotary
tool carrier of a dental engine hand piece such as are in common use. Figure 2 is a
view of the front end of the improved burr and Figure 3 is a similar view of the
front end of a burr of the old style. Figure 4 is a similar view of another form
of my improved burr and Figures 5, 6, 7 are respectively cross-sections of the
burrs shown in Figures 2 and 3 and a side elevation of the burr-head shown in
Figure 4.
The shank A of my improved burring tool may be of any desired or practical form
to adapt it to the carrier which is to rotate it.
My invention has relation only to the working end or head B of the tool, which
may be substantially round-a shape commonly employed-or of other form. Two
of the opposite cutting blades teeth or leaves b, of the burr head are or may be
substantially continuous as clearly shown in Figure 2 meeting at the extremity of the
axis of rotation and forming a single long cutting or drilling edge or blade, while
upon either side thereof the other cutting or burring leaves or edges, 61, are or may
be brought together in groups, as clearly shown outside the axis of rotation. There
is therefore a single drill or cutting edge at the axis of the burr, and the burr will, in
operation advance in this direction as readily as will a drill, which it practically is
while the large deep cuts upon either side allow the chips to pass back almost in
straight lines so as to free the burr as rapidly as the chips are cut. It is also evident
that when advancing in the direction of its axis, or drilling, there will be a much less
total length of cutting edge in operation than in the old form.
In practice it has been found that my improved burr will cut on the end or drill
with very much less pressure than is required by the old form of burr and will
advance, throwing the chips behind it more rapidly and without generating appreciable
heat. In opening a cavity in a tooth, for example it has been the custom with
careful operators owing to the difficulties referred to first to penetrate to the depth
necessary with a drill, and then, having exchanged the drill for a burr, to enlarge the
cavity to the required dimensions. With my improved burr-drill this change of tools
will be unnecessary, as the burr will perform the office of the drill in a superior
manner as well as do what has heretofore been thought to be its own proper
work.
In Figures 4 and 7 I have shown a form of my improved burr-drill differing from
that of Figures 1 and 2. The form shown in Figures 4 and 7 has the single cutting
or drilling edge at the extremity of the axis of the burr, but said edge is shorter
than in the form shown in Figure 2, an annular groove, c, being cut around the

page_text: crown or body of the burr, so as to form by the front projecting ends of the side
leaves or teeth b', virtually a circular cutting edge in rear of the front drilling edge
of the burr.
I deem it unnecessary to illustrate or describe other forms of my improved burr-
drill.
1 am aware that certain forms of burrs- such for instance as the "cherry
used to
smooth out cavities of bullet moulds have in some cases been formed with a scraping
edge crossing the end and a shallow groove on each side of the edge-such "cherries"
however were not formed substantially as the burr drill herein before described haring
extending across the axis of rotation of the tool, a drill elve formed with deep cu's or
clearance spares of the character I have described on either side to permit of the chips
removed by the edge getting away freely-these cherries therefore were not drills and could
not excavate progressively in an axial direction to any substantial extent; possessing
for that purpose no advantages over the form of burr which I have shewn at
Figure 3.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
The burr-drill consisting of the lateral burr-cutting edges and a drill-edge crossing
the axis of rotation of the tool, substantially as described.

page_text: Improvements in Dentists' Burring Tools.
I, SYDNEY PITT of Sutton in the County of Surrey Gentleman (a communication
to me from abroad by Arthur W. Browne, à Citizen of the United States, of Prince's
Bay, in the County of Richmond and State of New York) do hereby declare the
nature of this invention and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement :-
My invention relates to excavating or cavity burrs more especially designed for
dentists use.
Excavating or cavity burrs as made for dentists' use, are intended to cut their way
into the tooth substance, whether advanced after the manner of a drill, in the direction
of their axis of rotation, or at an angle to this axis. They are made in a variety of
forms and sizes to facilitate the excavating of all shapes and sizes of cavities. As a
large part of the cutting these tools are used for is done in sensitive dentinė, it is
extremely desirable that they be constructed to do the work with the least possible
pain to the patient. To accomplish this result, the burrs must cut freely without the
necessity of crowding them forward to their work and must free themselves constantly
from chips as in many cases when cutting in close proximity to a nerve the least
pressure or heat becomes almost unbearable. It is a fact that the old form of burrs
heretofore in use will cut with much less pressure and more freely when advanced in
a line at right angles to the axis of rotation than when advanced in the line of its
axis. Several reasons may be given for this.
First. The teeth or leaves of the burr all coming together at the end of the axis
there is no cutting-edge at this point. In fact it has usually been the practice to put
a small cut across the extreme end of the burr in which case in using the end of the
burrs there is a small projection of the material operated in, which cannot be cut by
the burr, and which must break away in order to allow the tool to advance.

page_text: Second. In advancing the burr in the line of its axis every tooth or leaf-and
there are usually eight-will be constantly cutting-while of advanced at right
angles to its axis two, or at most three teeth are all that can be brought into action
at any one time. It of course requires four times as much pressure to make eight
cutting edges of a given length penetrate the materials as would be necessary to
make two teeth of the same length take a like cut.
Third. It is a fact that in the old form of burr the spaces between the teeth or
leaves near the end of the axis of the burr are much narrower and the cuts shallower
than at any other portion, so that there is little room for chips, and it is found in
practice that the chips do not get away from the cutting edge freely enough to
prevent the spaces from choking, when of course there is great heat developed from
the resulting friction and very little cutting is accomplished.
The object of my present invention is to provide an improved burring tool in
which the objections to and imperfections in the old style of burr noted above will be
avoided.
The improvements will first be described with the aid of the accompanying
drawings sufficiently in detail to enable them to be clearly understood. I will then
distinctly recite the subject matter claimed herein as my invention at the close of this
specification.
In said drawings Figure 1 is a view of my improved burring tool with the shank
thereof having a flattened transversely-grooved driving end to adapt it to the rotary
tool carrier of a dental engine hand piece such as are in common use. Figure 2 is a
view of the front end of the improved burr and Figure 3 is a similar view of the
front end of a burr of the old style. Figure 4 is a similar view of another form
of my improved burr and Figures 5, 6, 7 are respectively cross-sections of the
burrs shown in Figures 2 and 3 and a side elevation of the burr-head shown in
Figure 4.
The shank A of my improved burring tool may be of any desired or practical form
to adapt it to the carrier which is to rotate it.
My invention has relation only to the working end or head B of the tool, which
may be substantially round-a shape commonly employed-or of other form. Two
of the opposite cutting blades teeth or leaves b, of the burr head are or may be
substantially continuous as clearly shown in Figure 2 meeting at the extremity of the
axis of rotation and forming a single long cutting or drilling edge or blade, while
upon either side thereof the other cutting or burring leaves or edges, b¹, are or may
be brought together in groups, as clearly shown outside the axis of rotation. There
is therefore a single drill or cutting edge at the axis of the burr, and the burr will, in
operation advance in this direction as readilly as will a drill, which it practically is
while the large deep cuts upon either side allow the chips to pass back almost in
straight line so as to free the burr as rapidly as the chips are cut. It is also evident
that when advancing in the direction of its axis, or drilling, there will be a much less
total length of cutting edge in operation than in the old form.
In practice it has been found that my improved burr will cut on the end or drill
with very much less pressure than is required by the old form of burr and will
advance, throwing the chips behind it more rapidly and without generating appreciable
heat. In opening a cavity in a tooth, for example it has been the custom with
careful operators owing to the difficulties referred to first to penetrate to the depth
necessary with a drill, and then, having exchanged the drill for a burr, to enlarge the
cavity to the required dimensions. With my improved burr-drill this change of tools
will be unnecessary, as the burr will perform the office of the drill in a superior
manner as well as do what has heretofore been thought to be its own proper
work.
In Figures 4 and 7 I have shown a form of my improved burr-drill differing from
that of Figures 1 and 2. The form shown in Figures 4 and 7 has the single cutting
or drilling edge b at the extremity of the axis of the burr, but said edge is shorter
than in the form shown in Figure 2, an annular groove, c, being cut around the

page_text: crown or body of the burr, so as to form by the front projecting ends of the side
leaves or teeth 6', virtually a circular cutting edge in rear of the front drilling edge
of the burr.
I deem it unnecessary to illustrate or describe other forms of my improved burr-
drill.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
The burr-drill consisting of the lateral burr-cutting edges and a drill-edge crossing
the axis of rotation of the tool, substantially as described.
Dated this 14th day of November 1887.
CARPMAEL & Co.,
Agents.