U.S. patent number 3,878,610 [Application Number 05/417,102] was granted by the patent office on 1975-04-22 for low profile dental impression tray and set of such trays.
Invention is credited to William Alfred Coscina.
United States Patent |
3,878,610 |
Coscina |
April 22, 1975 |
Low profile dental impression tray and set of such trays
Abstract
A set of dental impression trays for both mixed and permanent
dentition is provided wherein the members of the set differ
primarily in the size of the dental arch and lateral distance
between corresponding molar positions on opposite sides of the jaw.
A rise is provided in the retromolar and tuberosity areas of the
permanent dentition. Each tray in the set is a rigid low profile
member comprised of a narrow substantially planar U-shaped base,
lingual and labial walls integral with the base and upstanding from
opposite edges thereof to provide a generally U-shaped cross
section, an anterior handle projecting outwardly from the base and
the labial wall and lateral tabs on opposite sides of the anterior
handle extending laterally outwardly from the base at an acute
angle thereto, said lateral tabs being located at the
bicuspid/molar region on opposite sides of the tray. The base of
each tray within the set has the same transverse dimension in
respective locations of the tray.
Inventors: |
Coscina; William Alfred (New
Britain, CT) |
Family
ID: |
23652589 |
Appl.
No.: |
05/417,102 |
Filed: |
November 19, 1973 |
Current U.S.
Class: |
433/37 |
Current CPC
Class: |
A61C
9/0006 (20130101) |
Current International
Class: |
A61C
9/00 (20060101); A61c 009/00 () |
Field of
Search: |
;32/17,18 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Peshock; Robert
Attorney, Agent or Firm: Prutzman, Hayes, Kalb &
Chilton
Claims
I claim:
1. A rigid disposable low profile dental impression tray for
accurately registering a dentition for crown and bridgework
comprised of a narrow U-shaped substantially planar base of dental
arch configuration conforming in the posterior and lateral
curvatures to the occlusal surfaces of the dentition and inner and
outer walls integral with the base and upstanding from opposite
edges thereof to provide a trough of generally U-shaped cross
section, an anterior handle integrally projecting outwardly from
the base at an obtuse angle to both the base and the outer wall and
lateral tabs spaced on opposite sides of the anterior handle
extending laterally outwardly from the base at a more acute angle
than said anterior handle, said lateral tabs being located at about
the bicuspid/molar area on opposite sides of the tray, said
anterior handle being broader than the lateral tabs, said anterior
handle and lateral tabs facilitating simultaneous substantially
planar engagement thereof parallel to the occlusal masticatory
surfaces of the dentition for vertical withdrawal of the tray from
said surfaces, said inner and outer walls extending from the base
sufficiently only to accurately register the dentition and the
immediately adjacent periodontal supporting tissue.
2. The dental impression tray of claim 1 wherein the outer wall
extends integrally from the base for a height that encompasses the
soft supporting tissue by a distance up to at least one half the
length of the exposed teeth in confronting relationship
therewith.
3. The dental impression tray of claim 1 adapted for use as a
maxillary tray wherein the inner wall includes a lingually
projecting flange extending rearwardly from about the first
bicuspid area toward the second molar area, said flange providing a
palatal stop for the tray.
4. The dental impression tray of claim 1 wherein the anterior
handle is sufficiently larger than the lateral tabs to facilitate
engagement by two thumbs of the operator during vertical withdrawal
of the tray.
5. A set of dental impression trays as set forth in claim 1 wherein
each member of the set differs from other members thereof by both
the length of the dental arch and the transverse dimension between
corresponding teeth on opposite sides thereof.
6. The set of dental impression trays of claim 5 including a mixed
dentition tray and a plurality of permanent dentition trays wherein
the mixed dentition tray terminates at the second molar area and
the permanent dentition trays exhibit a molar rise extending
distally from the second molar area.
7. The set of dental impression trays of claim 5 wherein the
transverse dimension of the base of each member of the set is
substantially identical at corresponding locations.
8. The set of dental impression trays of claim 5 of the maxillary
type comprised of a mixed dentition tray and small, medium and
large dentition trays wherein the trays exhibit substantially the
dimensions set forth in the following table with the dimension for
the mixed tray being taken at the first molar area and the
dimensions for the permanent trays being taken at the second molar
area:
9. The set of dental impression trays of claim 5 of the mandibular
type comprised of a mixed dentition tray and small, medium and
large dentition trays wherein the trays exhibit substantially the
dimensions set forth in the following table with the dimension for
the mixed tray being taken at the first molar area and the
dimensions for the permanent trays being taken at the second molar
area:
10. The set of dental impression trays of claim 9 wherein the mixed
dentition tray terminates at the second molar area and the
permanent dentition trays include a molar rise distally of the
second molar area.
11. The set of dental impression trays of claim 5 of the maxillary
type wherein the interior walls of each tray are provided with a
lingually projecting flange extending rearwardly from about the
first bicuspid area toward the second molar area, said flange
providing a palatal stop for the tray.
12. The set of dental impression trays of claim 5 wherein the trays
are constructed of dimensionally stable plastic material.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates generally to dental impression trays.
More specifically it is concerned with a new and improved low
profile impression tray particularly well suited for crown and
bridgework and to a set of such trays.
It has been well established that the use of full models of a
patient's dentition and its surrounding soft periodontal tissue
provides the most accurate method of obtaining models for use in
crown and bridgework. However, impression trays utilized heretofore
to produce such full models for registration of the dentition have
been relatively large and bulky and have encompassed an excessive
amount of supporting soft tissue not truly necessary for the
desired registration of the dentition and soft tissue structure.
Such bulky structures require the use of inordinate amounts of
expensive impression material and frequently result in not only
unnecessary discomfort to the patient while the impression is being
taken but also gagging of the patient and irritation of the
patient's cheeks, mouth floor and palate. Additionally, when the
impression tray is used with "wash-type" impression material and,
it is necessary to reinsert the tray, it has been found that
distortions frequently occur in the impression and that marginal
registration is inaccurately taken due to the bulky nature of the
tray and particularly due to the fact that the dentist is limited
to the use of a single handle for the purposes of positioning and
manipulating the tray.
In some existing impression tray structures, the tray is provided
with a smooth interior surface and the impression material is
secured thereto by the use of the adhesive. However, it has been
found that such adhesively bonded structures tend to pull away from
the tray thereby causing added inconvenience to both the dentist
and the patient and frequently resulting in the necessity of taking
additional impressions thereby prolonging the "chair time" of the
patient.
Although various sets of adjustable and rigid dental impression
trays have been provided heretofore, the principal differences
between members in each set of trays have primarily been in the
length or distal extent of the dental tray and in the entire
relative size of each tray.
It has now been found that the principle variation in jaw sizes
occur in the length of the dental arch and the lateral distance
between corresponding teeth on opposite sides of the jaw.
Accordingly, it is an object of the present invention to provide a
new and improved low profile impression tray for accurately
registering the dentition and only as much of the soft periodontal
supporting structure as is needed to fabricate the desired
corrective device.
Another object of the present invention is to provide a new and
improved dental impression tray of the type described that includes
means which facilitate planar release of the impression from the
dentition thereby minimizing distortion and interference with
marginal registration. Included in this object is the provision for
an impression tray provided with a plurality of spaced handles
facilitating the planar release of the impression from the
dentition and reseating thereof in a facile manner without
adversely affecting the impression.
A further object of the present invention is to provide a new and
improved low profile impression tray of the type described having
an interior grid-like surface effective to increase the surface
area between the tray and the impression material to assure firm
secure engagement therebetween.
Still another object of the present invention is to provide a low
profile dental impression tray of the maxillary type having means
preventing overseating of the tray and the resultant spillage,
waste of impression material and irritation to the patient.
A still further object of the present invention is to provide a
disposable impression tray of the type described that is
constructed of inexpensive plastic material easily trimmed by the
dentist to accommodate only that portion of the dentition under
treatment, such as merely the dentition itself when used for
orthodontic models to which bands and appliances are to be applied.
Included in this object is the provision for a tray made of
material that can be readily sectionalized and adjusted to various
minor anatomical configurations and is ideally suited to a transfer
coping technique using rubber, plaster or combination
withdrawals.
Other objects will be in part obvious and in part pointed out in
more detail hereinafter.
These and related objects are accomplished in accordance with the
present invention by providing a set of dental impression trays for
both mixed and permanent dentition wherein the members of the set
differ primarily in the size of the dental arch and lateral
distance between corresponding molar positions on opposite sides of
the jaw and the inclusion of a rise in the retromolar and
tuberosity areas in the permanent dentition trays. Each tray in the
set is a rigid low profile member comprised of a narrow
substantially planar U-shaped base, lingual and labial walls
integral with the base and upstanding from opposite edges thereof
to provide a generally U-shaped cross section, an anterior handle
projecting outwardly from the base and the labial wall and lateral
tabs on opposite sides of the anterior handle extending laterally
outwardly from the base at an acute angle thereto, said lateral
tabs being located at the molar region on opposite sides of the
tray.
A better understanding of the invention will be obtained from the
following detailed description and the accompanying drawing which
set forth an illustrative embodiment indicative of the way in which
the principles of the invention are employed.
A BRIEF DESCRIPTION OF THE DRAWING
In the drawing:
FIG. 1 is a perspective view of an empty impression tray of the
mandibular type for use on permanent lower dentition;
FIG. 2 is a side view of the impression tray of FIG. 1 that has
been oriented for positioning within a patient's mouth to register
the lower dentition;
FIG. 3 is a plan view of a mixed dentition tray of the mandibular
type with phantom lines outlining the relative sizes of the three
permanent dentition trays in the same set;
FIG. 4 is a sectional view taken along the line 4--4 of FIG. 1;
FIG. 5 is a sectional view taken along the line 5--5 of FIG. 2;
FIG. 6 is a fragmentary side view of the mixed dentition tray of
FIG. 3 with a phantom line illustrating the relative size of the
molar area of the tray of FIG. 2.
FIG. 7 is a plan view of the exterior of a dental impression tray
of the maxillary type for use with the upper dentition and
incorporating the features of the present invention;
FIG. 8 is a side view, partially broken away, of the tray of FIG. 7
oriented for positioning in the patient's mouth to register the
upper dentition; and
FIG. 9 is a sectional view taken along the line 9--9 of FIG. 8.
DESCRIPTION OF A PREFERRED EMBODIMENT
Referring now to the drawing in greater detail wherein like
reference numerals indicate like parts throughout the several
figures, a mandibular or lower dentition tray 10 for permanent
teeth is shown as generally consisting of a U-shaped trough 12 for
holding the impression material and a plurality of
tray-manipulating handles 14 and 16. The particular tray 10
illustrated is of medium size; however, as will be appreciated from
FIG. 3, a set of mandibular trays conveniently consists of a mixed
dentition tray 18 and small, medium and large permanent dentition
trays 20, 10 and 22 respectively. These trays are very similar in
construction and therefore will be described primarily with respect
to the medium size mandibular tray 10. It will also be appreciated
that each corresponding size of a maxillary tray in a set will be
substantially identical in relative size except for the usual
difference between these two types of trays. Accordingly, for ease
of understanding and simplicity of illustration only the preferred
embodiment of a medium permanent tray 10 will be described in
detail. As will be appreciated, this embodiment of the tray
including the specific dimensions thereof are provided by way of
illustration only and are not intended to be a limit on the
practice of the invention.
Referring now specifically to FIGS. 1-5 the dental impression tray
indicated generally by the numeral 10 includes the trough 12
comprised of a narrow, generally planar base or floor portion 26 of
U-shaped configuration having a labial or outer wall portion 28 and
a lingual or inner wall portion 30 integrally upstanding from
opposite edges of the floor portion 26 in a continuous fashion
along its entire arcuate extent. As best shown in FIGS. 1, 4, and
5, the base 26 and integral labial and lingual wall portions 28 and
30 collectively impart a generally U-shaped cross sectional
configuration to the tray resulting in its troughlike appearance.
The wall portions extend outwardly from the base in relative
diverging fashion and are of a dimension sufficient to enclose the
usual height of a clinical crown as well as the lingual, crestal
and gingival attachments thereto. However, the wall portions do not
extend excessively beyond these attachment areas and unlike trays
utilized heretofore only exhibit a height which exceeds the exposed
tooth length by a distance equal to or less than one-half that
length.
Advantageously, one of the unique features of the present invention
is the consistently narrow dimension of the base or floor portion
26 in all trays within each set. In fact, these base or floor
portions are substantially identical in the small, medium and large
permanent dentition members of the set as well as in the mixed
dentition tray. As mentioned hereinbefore, the base or floor
portion 26 is substantially planar and of generally U-shaped
configuration; however, as best shown in FIG. 2, it exhibits a
slight concave curvature from front to back, commonly referred to
as the Curve of Spee. The slight arcuate configuration extends from
the central portion of the tray rearwardly toward the second molar
area. Distally beyond that point the floor exhibits a substantially
increased curvature referred to as the retromolar rise. That area,
designated by the numeral 31, is slightly exaggerated in FIGS. 2
and 6 for illustrative purposes.
The breadth of base portion 26 increases slightly from the central
portion of the tray toward the retromolar rise 31 and in the
preferred embodiment exhibits dimensions of approximately 10 mm at
the central area with a gradual increase in about 12 mm at the
bicuspid area and 16 mm at the second molar area of each tray. As
mentioned, it is an advantageous feature of the present invention
that the foregoing dimensions remain substantially constant for the
small, medium and large permanent dentition trays and preferably
are also utilized in the mixed dentition tray of each set. In this
way the amount of impression material that must be used may be held
to a minimum while at the same time fully and completely
accommodating all of the teeth regardless of the size of the tray
that need be used.
As mentioned, another feature of the present invention is the low
profile labial and lingual walls of the tray. As shown in FIGS. 1
and 2, the labial or outer wall portion 28 is integrally joined to
the base portion along one edge thereof and depends therefrom along
the entire extent of the U-shaped base portion. The distance of the
free edge 32 of the labial or outer wall portion 28 from the base
portion 26 varies along its length in order to accommodate certain
muscle and soft tissue areas. For example, at the central portion
of the tray the free edge of the labial wall portion is provided
with a recess or cleft 34 to accommodate the labial frena.
Accordingly, the dimension of the wall portion at the frenum area
is only about 12 mm as compared to a conventional lower anterior
central tooth length of about 8-11 mm. The free edge 32 gradually
undulates as it sweeps rearwardly, the undulation providing a
muscle relief portion 36 in the bicuspid area having a height of
about 12 mm bounded by crests 40, 42 on opposite sides thereof
having wall dimensions of about 14 mm and 16 mm, respectively. As
seen in FIGS. 1 and 2, the labial wall falls off sharply in the
retromolar area 31 to a dimension of only about 9 mm immediately
prior to joining the base or floor portion 26.
The labial wall portion 28 not only varies in depth but also in
angular disposition relative to the base portion 26 as the wall
extends rearwardly. For example, the labial wall at the cleft 34 is
disposed at an angle of 90 degrees to the base or floor portion 26
and maintains this relationship across the full anterior extent of
the tray. However, in the cuspid area the wall portion 28 starts to
flare slightly labially so that it is disposed at an angle of 105
degrees to the base portion 26 as the wall reaches the second
bicuspid area of the tray.
The lingual or inner wall portion 30, on the other hand, is
disposed at an angle of about 120 degrees to the base 26 at the
midline of the tray and is of a substantially constant dimension in
the central area, i.e. about 12 mm, until it reaches the biscuspid
area where it initiates a gradual increase to a dimension of about
16 mm in the molar area and adjusts to an angle of about 105
degrees. This low profile angular relationship of the walls to the
base also substantially limits the amount of impression material
required by the tray of the present invention.
As best shown in FIG. 1, the interior of the trough 12 defined by
the base and wall portions is provided with a scored, serrated or
grid-like roughened surface configuration. This permits greater
surface area contact between the interior of the tray and the
impression material carried therein thereby obviating the
difficulties formerly encountered when the impression material
readily separated from the tray. At the same time this is
accomplished without the necessity for apertures and is
particularly effective when adhesive is applied to the interior of
the tray so as to secure the impression material therein.
One of the particularly unique features of the present invention is
the provision for a plurality of spaced tray manipulating handles.
In the preferred embodiment three such handles are provided, a
central or anterior handle 14 and a pair of lateral handles 16 on
opposite sides of the anterior handle 14. All three handles extend
outwardly from the labial or outer wall 28 at its point of juncture
with the base or floor portion 26. Although these handles or tabs
can be of identical length, preferably the anterior handle 14 is
slightly larger than the lateral handles 16 by about 3-7 mm. The
three handles positively locate three points of the plane of
withdrawal of the tray and are of substantial assistance in holding
the tray level as it is lifted from the dentition. This is
particularly important since the lateral handles permit a
withdrawal force at the distal portion of the impression
simultaneously with a withdrawal force applied at the anterior
portion of the tray. The tray thus can be lifted straight up
without subjecting the tray to the angular forces that are required
when only a single anterior handle is used to effect withdrawal of
the impression from the dentition. In the specific embodiment used
for illustrative purposes and as best shown in FIGS. 2, 4 and 5,
the anterior handle 14 is of greater length than the lateral
handles 16 and may, for example, be of a length of about 16 mm
while the lateral handles exhibit a length of only about 9 mm.
Additionally, the anterior handle 14 is disposed at an angle of
about 120 degrees to the labial or outer wall 28 and at an angle of
about 150 degrees to the base or floor portion 26 of the tray. On
the other hand, the lateral handles or tabs 16 are disposed at an
angle of about 120 degrees to the labial side wall 28 and at an
angle of about 135 degrees to the floor portion 26 of the tray. The
anterior handle 14 is also contoured so that it can easily
accommodate the dentist's thumbs during removal of the tray. In
operation, after the impression material has set on the dentition,
the dentist need merely contact the underside of the anterior
handle 14 with his thumbs and the underside of the lateral handles
with his index fingers and lift the tray away from the dentition by
a smooth, upward movement which provides for a clean unobstructed
withdrawal for a true unaltered registration of the dentition.
As mentioned, it is a feature of the present invention that the
floor portion in each member of the dental tray set remains
substantially unchanged but that each member varies from other
members of the set primarily by the lateral distance between
corresponding teeth and by the length of the dental arch.
Accordingly, as shown in FIG. 3 the mixed small, medium and large
trays of the set vary in the dental arch and in the lateral
dimension between corresponding molars. The particular arch form
can easily be obtained by three measurements, namely the lateral
distance between corresponding molars, such as the first molar line
48 of tray 18 and the second molar line 50 of tray 20 shown in FIG.
3, the center line distance 52 or 54 between the laterally
extending lines 48 or 50 and the center of the tray floor at the
center line and the peripheral dimension of the tray between
corresponding molars on opposite sides of the tray. In accordance
with the present invention, it has been found that only three trays
are required to accommodate a wide variety of jaw forms where
permanent teeth are involved and only a single tray is required for
jaws of mixed dentition. Thus a set of only four trays will readily
accommodate substantially all jaw configurations for patients of
about seven years of age and older. Typical measurements for these
four trays of both the maxillary and mandibular type are set forth
in Table I;
Table I
__________________________________________________________________________
Maxillary Mandibular Tray Lateral Center Periphery Lateral Center
Periphery
__________________________________________________________________________
Mixed 1.63" 1.00" 4.38" 1.63" 0.87" 4.25" Small 2.00" 1.38" 5.00"
1.86" 1.25" 4.75" Medium 2.13" 1.50" 5.50" 2.00" 1.38" 5.00" Large
2.25" 1.75" 5.75" 2.13" 1.50" 5.25"
__________________________________________________________________________
As will be appreciated, the mixed dentition tray does not include a
retromolar rise and the lateral measurement between corresponding
teeth on opposite sides of the jaws are generally taken across the
first molar location rather than the second molar location.
Additionally, since it does not have a retromolar rise portion, the
mixed dentition tray 18 exhibits a slightly different configuration
from the remaining trays in the set. This difference in
configuration is best illustrated in FIG. 6 where the molar area of
the mixed dentition tray is shown in relationship to the medium
size tray 10 of FIG. 2.
Referring now to the maxillary tray 60 illustrated in FIGS. 7-9,
the tray construction is similar to that discussed in connection
with the mandibular trays. However, as is apparent from FIG. 8, the
generally planar U-shaped base or floor portion 62 of the maxillary
tray 60 exhibits a slight convex curvature corresponding to the
Curve of Spee and complementary to the base portion 26 on the
mandibular tray. The lingual wall portion 64 is provided with a
palatal stop that takes the form of flanges 66 on the top free
surface of the lingual wall at the molar area. As shown, the
flanges 66 starts at a point distal to the first bicuspid and
extends rearwardly to the second molar area. The flanges are not of
substantial breadth, exhibiting a width of only about 5 mm and are
disposed at an angle of about 135 degrees to the lingual wall 64.
As can be apapreciated the inwardly extending flanges 66 prevent
overseating of the low profile and prevent possible irritation to
the patient accomapnying such overseating.
In a mannner complementary to the mandibular tray, the maxillary
tray includes a tuberosity rise 68 on the free or terminal ends
thereof and, as shown in FIG. 8, also includes a grid-like or
serrated inner surface 70 to provide improved retention of the
impression material within the tray. The labial wall portion 72 is
angularly disposed relative to the floor portion 62 at
substantially the same angle as the corresponding wall 28 of the
mandibular tray while the lingual wall 64 preferably is disposed at
a constant 120 degree angle to floor portion 62 throughout the
length of wall 64. Additionally, the labial wall portion 72
exhibits substantially the same undulating configurations as wall
portion 28 to provide relief for the frenum and muscle areas in the
upper jaw.
Although the anterior and laterial handles 74, 76, respectively of
the maxillary tray 60 can be of a size and angulr relationship
substantially identical to the three tabs on the mandibular tray,
it is generally preferred that the anterior handle 74 of the
maxillary tray extend at an angle of about 105 degrees relative to
the labial wall portion 72 rather than the 120 degrees orientation
exhibited by the handle 14 and that the lateral tabs or handles 76
extend labially at an angle of 120 degrees to the base or floor
portion 62 rather than the 135 degree orientation of the tabs 16 of
the mandibular tray. Additionally, the lateral tabs or handles 76
on the maxillary tray are slightly shorter, extending for a
distance of about only 6 mm rather than the 9 mm length preferred
for tabs 16. As will be appreciated, a set of maxillary trays will
correspond in number and size to the set of mandibular trays
discussed hereinbefore.
Although the trays in each set may be made from a variety of
different materials, it is generally preferred that rigid, low-cost
plastic be employed. The particular type of plastic is not critical
although it should exhibit the dimensional stability or rigidity
necessary to provide the desired result. In addition to low cost,
the plastic should facilitate easy sectionalization and trimming of
the wall portions to accomodate the individual patient. For
assisting in sectionalization each tray is provided with score
lines, such as the lines 80 on the exterior tray 10 at the
locations of each tab or handle. As shown, the score lines 80
preferably bisect each handle or tab so that tab portions remain
functional even though only a section of the tray is utilized. For
example, if an impression is required for only the anterior
dentition, the tray can be broken on the score lines located at
each lateral handle 16 and the advantageous three point
manipulation of the tray is retained.
Thus, as can be seen by the foregoing detailed description, the
present invention provides a new and improved dental impression
tray which includes three tabs or handles for even, plane-like
withdrawal of the impression from the dentition. The handles are
short strong angulated members designed so as not to interfere with
the sides of the mouth or with the placement and removal of the
impressions. Additionally, the trays provide a retromolar rise and
tuberosity rise within the distal molar area and the maxillary tray
provides an angulated flange stop to prevent overseating and
resultant irritation. The labial and lingual walls of the tray are
of low profile to minimize the amount of impression material
required while at the same time provide relief for frenum and
muscle attachments. As will be appreciated, the trays are
preferably made from material that can be readily cut away in order
to easily adjust the side walls to accommodate the particular
patient. Further, a gridlike interior surface is provided on the
trays to improve retention of the impression material and is
particularly effective in combination with adhesive coatings. The
tray is of simple yet sturdy design and can be made from
inexpensive plastic material so as to facilitate its use and
disposal. The set of trays employ a floor or base portion which is
substantially uniform throughout each member of the set with each
member varying from other members principally by the lateral
distance between corresponding teeth and by the size of the dental
arch.
As will be appreciated by persons skilled in the art, various
modifications, adaptations and variations of the foregoing specific
disclosure can be made without departing from the teachings of the
present invention.
* * * * *