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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to dental implements. More specifically, it
relates to a retaining aid for the metal contour band placed around a
tooth when a proximalocclusal cavity in the tooth is to be filled. The
device allows for improved contact between the contour band and the
adjacent tooth which assures that the tooth worked upon will be in contact
with the adjacent tooth after the cavity is filled. The retaining aid of
the present invention has a generally arcuate and resilient main body with
a pair of downward and inwardly depending tines or legs on each end. The
distal ends of the legs can be slightly bulbous and may be coated or
dipped in a substance imparting a high friction coefficient thereto.
Optionally, the tips could be flattened or adapted to receive a disposable
cover made of a rubber or like substance or simply have a bulbous tip in
metal.
2. Description of the Prior Art
When the decayed portion of a tooth is located near the interproximal area
between adjacent teeth, the most common way to guarantee that the filling
properly conforms to the original shape of the tooth is to set a tooth
reconstruction element, such as a thin band usually made of stainless
steel or the like, about the tooth and secure it tightly thereto such that
the band forms an outer shell or matrix that allows the filling material
to harden in the correct shape. The present invention is an apparatus that
aides the practitioner in retaining the matrix band in proper proximity to
the tooth being worked upon. The resilience of the arcuate main body
provides for the two depending legs to be urged inwardly toward one
another to ensure a conforming matrix fit and also holds the retaining
apparatus in place.
The depending legs can be of varying lengths to allow a plurality of the
devices to be superimposed, one above the other, to allow for complex
restoration processes or allows more than one tooth to be worked on at a
time. A material providing a high frictional coefficient that can be
coated onto the bulbous tips of the legs helps to prevent the apparatus
from slipping and allows the device to be used with a variety of
differently shaped teeth. A search at the U.S. Patent and Trademark Office
uncovered a number of patents that relate to this invention, and they are
discussed hereinafter.
First is U.S. Pat. No. 4,824,365 issued on Apr. 25, 1989 to Hans von
Weissenfluh. This discloses a matrix in a flexible strip with an integral
tightener. The flexible strip has two terminal extensions that are
fastened to tabs extending from an annular tightener made of permanently
deformable material. Thus, when the tightener is compressed, the flexible
loop around the tooth is likewise tightened. This is dissimilar from the
present invention in that there is no teaching of a separate flexible
retainer with the depending legs.
In U.S. Pat. No. 4,303,389 issued on Dec. 1, 1981 to Angelo Salsarulo there
is disclosed an instrument for the application of fillings. Though this
discloses a matrix retainer that has an open end, there are no depending
legs for engagement with the matrix.
U.S. Pat. No. 2,790,238 issued on Apr. 30, 1957 to Frank M. Trangmar
discloses a dental matrix having a thicker, deformable portion to
facilitate tightening the unit about the tooth to be worked on. Clearly,
this is dissimilar from the present invention in that there is no
resilient body with depending legs to aid in guaranteeing the
interproximal contact between teeth after the filling has hardened.
U.S. Pat. No. 2,567,101 issued on Sep. 4, 1951 to Victor H. Carpenter
discloses a matrix band for use in filling dental cavities. This band
includes a spherical concavity located at a point thereon to allow for a
rounded filling after hardening, thereby maintaining the proximal contact
between the teeth. This is unlike the present invention in that no matrix
retaining means is disclosed.
U.S. Pat. No. 3,548,500 issued on Dec. 22, 1970 to Theodore J. Cohen
discloses a method of taking dental impressions. This is clearly
dissimilar from the instant invention in that no separate retaining means
for the matrix holder is taught.
U.S. Pat. No. 677,268 issued on Jun. 25, 1901 to Roscoe 0. Power discloses
a dental instrument. This invention includes a horseshoe-shaped spring
clamp to hold the matrix retainer in place, however there is no teaching
of the depending legs and bulbous gripping tips of the present invention.
Lastly, U.S. Pat. No. 644,705 issued on Mar. 6, 1900 to George Evans
discloses an impression band for dentistry. Projections are formed or
soldered onto the side of the band ring and when the impression hardens,
the ring is thus removed with the impression material. Contrast this to
the present invention wherein depending legs apply pressure to the
interproximal spaces bound by the matrix retainers.
None of the above inventions and patents, taken either singly or in
combination, is seen to describe the instant invention as claimed.
SUMMARY OF THE INVENTION
The present invention is a substantially ting-shaped device with a pair of
depending and converging legs on either of the distal ends. At the end of
the depending legs, a slightly bulbous area is formed, and this area may
be coated or otherwise sheathed in a substance which increases the
frictional co-efficient of the leg end. Thus, the device may be spread by
a tool and placed near the interproximal portion of a tooth that is being
worked on to help retain the matrix band in place. The substance sheathing
the bulbous leg ends helps to prevent the device from slipping or "popping
off". It is contemplated that rings according to this invention could be
made with a number of different leg lengths so that more than one could be
set in place on either side of a tooth, allowing more than one restoration
or one interproximal surface to be done at a time.
Accordingly, it is a major goal of the invention to provide a sectional
matrix retainer for dental restorations that overcomes the disadvantages
of the prior art.
Moreover, it is a principal object of the invention to provide a sectional
matrix retainer for dental restorations wherein the depending and
converging legs from the ring-shaped main body have bulbous tips which may
be sheathed in a substance to increase the frictional coefficient and thus
help prevent the retainer from inadvertently slipping off.
It is another object of the invention to provide a sectional matrix
retainer for dental restorations wherein by varying the lengths of the
depending legs, more than one ring may be placed about the teeth being
worked on.
It is an object of the invention to provide improved elements and
arrangements thereof in an apparatus for the purposes described which is
inexpensive, dependable and fully effective in accomplishing its intended
purposes.
These and other objects of the present invention will become readily
apparent upon further review of the following specification and drawings.
The present invention meets or exceeds all the above objects and goals.
Upon further study of the specification and appended claims, further
objects and advantages of this invention will become apparent to those
skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
Various other objects, features, and attendant advantages of the present
invention will become more fully appreciated as the same becomes better
understood when considered in conjunction with the accompanying drawings,
in which like reference characters designate the same or similar parts
throughout the several views, and wherein:
FIG. 1 is a front elevational view of a first embodiment of an improved
matrix retainer apparatus according to the present invention showing the
depending converging legs with the expanded or bulbous tips thereon;
FIG. 2 is a side view of a dental restoration process showing the matrix
retainer in place and with two of the retaining rings having differing leg
lengths in place;
FIG. 3 is a top view of a similar restoration process to that seen in FIG.
2;
FIG. 4 is a front elevational view of a second embodiment of an improved
matrix retainer apparatus according to the invention; and
FIG. 5 is a front-elevational view of a third embodiment of an improved
matrix retainer apparatus according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The first embodiment of a matrix retainer apparatus 10 according to the
invention consists of a main body 12, that is generally ring shaped and
lies in a plane PI. Depending from either end of this ring shaped portion
12 are a pair of depending and converging tines or legs 14. The depending
legs are of equal length, though it should be noted here that various
lengths of these legs are contemplated to allow more than one retainer 10
to be used at a time. Thus will be discussed further hereinafter. At the
end of each of the depending legs 14 of the first embodiment are knobs or
bulbous tips 16. These bulbous tips 16 are smooth and assist in gripping
the interproximal areas of the tooth being worked on, and thus retain that
portion of the tooth reconstruction element or matrix 100 (seen in FIGS. 2
and 3) in close proximity to the desired shape. The tips 16 can be coated
with a substance to increase the frictional coefficient of the surface to
prevent the retainer apparatus 10 from slipping or popping off during the
restoration procedure. As practitioners are well aware, this is a real
problem during procedures with present art devices, leading to discomfort
and annoyance to both the patient and the doctor. One such material that
has been found to serve in this capacity is PLASTISOL, manufactured by
Plast-o-meric Inc. located at 733 East Water Street, P.O. Box 247, North
Baltimore, Ohio 45872. This is a PVC-based coating that increases the
frictional coefficient sufficiently and has been shown to be able to stand
up to the heat of an autoclave without degradation. The tips 16 of the
device 10 are dipped in this material and allowed to dry. The material
preferably used for the main body, legs, and tips of the invention would
be stainless steel spring wire, although other materials could be used.
Preferably, the wire is circular in cross section. Other methods of
providing a higher frictional coefficient could be used, such as
removable, disposable rubber sheaths that fit over the tips 16.
If the main body 12 is formed from spring wire, the resilience of the main
body 12 tends to urge the legs 14 toward one another. Preferably, the
spacing between the two legs 14 is less than the spacing between the
opposed sides of a tooth to be restored. With the use of a suitable pair
of dental pliers, the user can manipulate the ring 10 to increase the
distance between the legs 14 (indicated by arrow A1 in FIG. 1) so that the
legs can be placed across the buccolingual width of the interproximal
tooth area in question (as seen in FIGS. 2 and 3) and the resilience of
the main body 12 in conjunction with the bulbous tips 16 will maintain the
device 10 in place and will also urge the retaining matrix into the
correct shape.
The invention is also directed to a matrix restoration system whereby
multiple rings 10 can be utilized for a wide variety of restoration
processes and complex restoration processes. Experimentation has shown
that rings having main body diameters of 0.675", 0.750", and 0.825"
(inches) are suitable for the most common applications. In addition, the
system includes rings having legs of differing length. One ring would have
legs of a first prescribed length and the second ring would have legs
greater than the first length. With this structure, the rings can be
stacked one upon another, as described below, for complex restoration
processes. Experimentation has shown that forming a first ring with legs
which are 0.270" in length and a second ring with legs which are 0.370"
(inches) in length are adaptable for a wide variety of restoration
processes. The difference in leg length between the two rings can be as
little as one millimeter and still achieve the overall advantages of the
system. Preferably, the spacing between the depending legs is 0.10"
(inches) with the dimensions being indicated at 24 in FIG. 1.
In use in a restoration of an occlusoproximal cavity (indicated at C in
FIG. 3) in a tooth, a matrix band 100 is fitted to and placed around the
tooth T that is to be worked on. To insure that the hardened filling,
whether of the amalgam or composite resin type is of the correct shape,
i.e. insuring proper contact between the cavity containing tooth and its
neighbor, the present invention is manipulated by either a tool, i.e. a
rubber dam forceps, in the direction indicated by arrow A1 in FIG. 1
spreading open the bulbous tips 16 and legs 14 so that the device 10 can
be placed across the buccolingual width of the interproximal area of the
two teeth, as can be clearly seen in FIGS. 2 and 3. The resilience of the
main body 12 both holds the device 10 in place and also urges the matrix
band 100 into the proper shape at the interproximal area to ensure that
the adjacent teeth will maintain proper contact with one another after the
filling has hardened. To aid in the separation and approximate the
gingival portion of the tooth during the dental restoration process, a
wedge W may be placed in the interproximal area in addition to the
depending converging legs 14 of the device 10. The high frictional
coefficient of the coating or sheath on the tip 16 is sufficient to
prevent the inadvertent dislodgement of the device 10.
The utility of the differing lengths of the legs will now be discussed.
Referring to FIG. 2, it can be seen that a pair of devices 10 can be
superimposed that one with longer legs 14A can be placed on top of the one
with shorter legs 14B. Thus, as seen in FIG. 3, if two interproximal
carious tooth portions needed to be restored, the matrix 100 could be held
at both interproximal areas to ensure proper fitting. It is contemplated
even more of the retaining devices 10 could be used to allow for the
dentist to perform three surface restorations at one time, both saving
time, money, and patient discomfort.
In the first embodiment seen in FIGS. 1-3, the legs 14 are coated with a
suitable polymeric material such as heat-resistant vinyl and the like.
FIG. 4 depicts another embodiment of the matrix retainer apparatus
according to the invention. In this embodiment, the apparatus 30 comprises
a retainer ring 32 having a pair of spaced apart ends 34, 36 and a pair of
downwardly extending tines or legs 38, 40. The legs 38, 40 have a retainer
member formed thereon to provide means for retaining the apparatus 30 on
the tooth in the operative position. In this embodiment, the retainer
member comprises a flattened head 42, 44 formed on the distal ends of the
legs 38, 40. The flattened heads can be formed by any number of
conventional processes. Preferably, the legs 38, 40 taper inwardly so that
the spacing between the proximal ends of the two legs 38, 40 is greater
than the spacing between the distal ends 42, 44 of the two legs 38, 40.
This structure can be important in proper positioning of the device 10 on
the matrix band 100 and the tooth being restored. Most teeth are bulbous
in that the base is slightly narrower than the body of the tooth. The
taper of the legs helps to accommodate the bulbous tooth structure and
ensure that the distal ends of the device 10 tightly grip the matrix band
100 and hold it in place without interference from the body of the tooth.
This creates an effective mechanical mounting of the device on the
contoured tooth and matrix band. Preferably, the angle of taper of the
legs is 7 degrees. However, a taper in the range of 4 to 30 degrees will
achieve the above-stated advantages.
FIG. 5 depicts a third embodiment of the matrix retainer apparatus
according to the invention. In this embodiment, the retainer apparatus 50
comprises a retainer ring 52 with a pair of spaced apart ends 54, 56 and a
pair of tines or legs 58, 60 depending from the ends 54, 56. In this
embodiment, the retaining member comprises a roughened bulbous head 62, 64
provided at the distal end of the legs 58, 60. Preferably, the bulbous
heads 62, 64 are formed by depositing or melting metal on the end by
soldering, welding or some other metal forming process. In addition, the
exterior surface of the heads 62, 64 are preferably roughened to enhance
the coefficient of friction between the retaining member and the matrix
band 100 when the apparatus 50 is in the operative position.
The matrix retainer apparatus according to the invention shows several
different embodiments of retaining members provided on the legs of the
apparatus. It is to be understood that any means for mechanically or
structurally increasing the coefficient of friction between the legs and
the band 100 and/or tooth T fall within the scope of the invention.
This system has been designed to adapt to various individual
occlusal-gingival heights along with various buccolingual widths between
molar-to-molar, molar-to-bicuspid, and primary-to-primary tooth contacts.
The depending legs converging with one another allow for consistent
placement about a wide variety of teeth without the concern that device
could spring off.
It is to be understood that the present invention is not limited to the
sole embodiment described above, but encompasses any and all embodiments
within the scope of the following claims.
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