Combined denture mold dewaxer and curing basin

A basin for simultaneous or consecutive dewaxing and curing of denture molds is disclosed. The basin is generally box-shaped and is provided with three vertically-shaped trays of which the topmost remains above the high fluid level. The upper rear portion of the basin has a pivotally-secured frame-arm provided with a plurality of nozzles adapted to spray over the entire area of the topmost tray. The fluid from the nozzles drains back into the basin; a recirculating pump recirculates the fluid back into the nozzles. A separate fluid inlet is provided to fill the basin for curing. The basin is further provided with an upper and lower fluid level-limiting means, a heating element, a thermostat and, preferably, an automatic timer.

FIELD OF THE INVENTION 
The present invention relates to an improved apparatus for denture 
fabrication, more specifically to a basin adapted to remove wax from and 
cure denture molds in the same basin. 
BACKGROUND OF THE INVENTION 
As is well known in the art, the preparation of dentures involves the 
following steps: 
(a) imprints of the gums of a subject are made with agar or suitable 
material (called the "negative"); 
(b) a model of each "negative" is made in plaster (called the "positive"); 
(c) the model is placed in the lower half of a flask and a surrounding 
parting surface is provided; 
(d) the model is covered with a thin layer of wax into which a set of teeth 
is embedded; 
(e) the upper half of the flask is added and filled with plaster, which, 
when set, holds the teeth in position; 
(f) the wax is removed and the denture material is introduced; 
(g) the denture material, usually a resin-type plastic, is cured. 
Till now the last two steps were done in separate operations. For example, 
the removal of wax is usually carried out in an ordinary sink under the 
hot water faucet, thus creating the problem of wax accumulating in the 
drain and plugging the same when the wax hardens. To overcome this 
disadvantage, U.S. Pat. No. 3,061,898 to Maliszewski discloses a basin 
which incorporates a hand-held hose and nozzle. The latter is either 
directed into the basin containing the flasks to be dewaxed or over the 
top of the basin where the flasks are held by tongs with the other hand. 
This can be dangerous as the flasks are usually cleaned of wax by water 
close to or at the boiling point. 
Two other U.S. patents describe a process and apparatus directed to cure 
the denture material properly: U.S. Pat. Nos. 2,498,368 and 2,360,986 to 
Harrison and Taub, respectively. However, neither of these patents 
disclosed a basin wherein both the dewaxing and curing steps can be 
carried out simultaneously or consecutively; the first Patent being a 
process and the second Patent being an apparatus adapted to cure a flask 
by placing a heating element inside the latter. 
OBJECTS OF THE INVENTION 
In view of the above, it is an important object of this invention to 
provide a basin conceived to both dewax and cure a denture mold in 
simultaneous or consecutive steps. 
It is another object of this invention to provide a basin provided with 
specially-formed spray means to carry out the dewaxing of denture molds. 
It is yet another object of the invention to provide a basin adapted to 
contain a curing fluid, means to heat the fluid to a desired temperature 
and support means for the denture molds. 
It is still another object of the present invention to provide a basin of 
the above type, which is simple in design and inexpensive to manufacture. 
SUMMARY OF THE INVENTION 
The above and other objects and advantages of the invention are realized 
according to a preferred embodiment comprising a basin having side walls, 
a rear wall, a front wall and a bottom floor wall as well as, preferably, 
an anti-vapor cover. The basin is adapted to be filled to predetermined 
levels with fluid (usually water). 
The interior space of the basin is provided with a first topmost tray which 
extends horizontally from end wall to end wall of the basin. Support means 
are provided for the tray and the latter always remains above the fluid 
level in the basin. 
Second and third trays are also provided in the basin, being downwardly 
spaced from the first tray and also vertically spaced from each other. 
Support means are provided for the second and third trays. 
All three trays are perforated in thin bottoms and sides with a plurality 
of holes, allowing the fluid in the basin to circulate freely 
therethrough. 
Dewaxing of the denture molds is achieved by firstly placing the flasks in 
the basin, immersed, until the wax is hot enough to permit separation of 
the flask halves; and, secondly, by placing the separated flask halves in 
the first tray. To finish the dewaxing process, a frame-arm extending 
across the top of the basin is pivotally secured to the basin adjacent the 
upper rear edge thereof. This frame-arm is provided with spaced-apart 
shower nozzles, as many as needed to spray over the entire area of the 
topmost tray. The arm is adapted to pivot from a horizontal position 
overlying the topmost tray to a substantially vertical position to allow 
easy access to the topmost tray. 
Pump means are provided to continuously circulate the fluid back into the 
shower nozzles after it has drained into the basin. 
Switch means are also provided to deactivate the pump when the arm is 
pivoted to the vertical position, thereby shutting off the water supply to 
the nozzles. 
It will be readily understood that the dewaxing operation is carried out by 
placing the half-flasks in the topmost tray and pivoting the arm 
downwardly into horizontal spray position until the last vestiges of wax 
are removed from the flasks. Then the latter are ready for the final 
curing step. 
To accomplish the latter, the half-flasks are closed together and placed in 
the lower second tray, or third tray. Then the basin is filled to a 
predetermined level with fluid, such that the flasks are completely 
immersed in the fluid. The latter is heated to a desired curing 
temperature by heating means. The curing temperature is maintained at a 
constant degree by a thermostat. Preferably, an automatic timer is also 
provided to deactivate the heating means after the necessary curing time. 
It is to be noted that the heating means remains at all times submerged in 
the fluid to prevent burning-out. Therefore, preferably, an automatic 
fluid level regulating means is provided in the basin to regulate the 
upper and lower fluid levels in the basin, the lower level being just 
above the heating means and, when the basin is filled, the upper level 
being just under the topmost tray. 
A valve separate from the circulating pump is provided to fill the basin 
for curing. It is connected to a fluid supply source.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The preferred embodiment of the invention comprises a basin 1 mounted in a 
suitable box-like frame 2, as suggested in FIGS. 1 and 2. Basin 1 has a 
pair of opposite end walls 3, a rear wall 4, a front wall 5, a floor 6 
and, preferably, an anti-vapor cover 7 (seen only in FIG. 2). Basin 1 is 
adapted to be filled with fluid 8 (usually hot water). 
The interior space of basin 1 is occupied by three vertically-spaced trays: 
a topmost tray 9, a middle tray 10 and a third lowermost tray 11. All 
three trays are perforated with a plurality of holes 12 to allow fluid 8 
to circulate freely therethrough. Preferably, topmost tray 9 and middle 
tray 10 are of a substantially lesser width than the width of basin 1 and 
are slidably mounted for transverse movement on guideways 13. This is to 
facilitate access to the lowermost tray 11. The latter is preferably 
supported above the floor 6 of basin 1 by legs 11' at each of its corners. 
An electric heating element 14 is provided to heat the fluid 8. It is 
located under lowermost tray 11 adjacent floor 6. 
It is to be noted that element 14 remains always submerged in the water of 
basin 1. To ensure that the water level does not fall low enough to expose 
element 14 (and, thus, risk its burning-out), a water level sensor 15 is 
provided in one of the end walls 3 (cf. FIG. 1) just above element 14. 
When the water level falls low enough in basin 1, sensor 15 activates an 
electric inlet valve 16 which is connected to an external water supply 
(not shown). Basin 1 is also provided with a drain 17 to empty the water 
down to the level of sensor 15, as needed. 
An upper water level limiting means has also been provided for in-basin 1, 
consisting of a second sensor 18 located in one of the end walls 3 just 
under topmost tray 9. When the water level reaches sensor 18, the latter 
shuts off inlet valve 16 automatically. 
The elements of basin 1 further include a frame-arm 19 extending from end 
to end of basin 1 and pivotally secured thereto adjacent the upper rear 
edge thereof. Frame-arm 19 is provided with a plurality of shower nozzles 
20, which are adapted to spray water over the entire surface of topmost 
tray 9. Arm 19 is pivotally secured by means of pins 21. These latter are 
of hallow construction and constitute inlet nipples for the water flowing 
into arm 19 which, of course, is also hollow. 
Each pin 21 is connected by means of feed pipes 22 to a recirculating pump 
23 located in frame 2 underneath floor 6 of the basin. A return pipe 24 
communicates with the floor 6 of basin 1 at one end and is connected to 
pump 23 at its other end. Thus, as will be readily understood, the heated 
water 8 is pumped through shower nozzles 20, which then drains into basin 
1 through return pipe 24 and back to pump 23 for recirculation. 
Referring now to FIG. 3, there is shown a denture mold flask 25, made of 
suitable rigid material, as commonly used in the art. Flask 25 is made in 
two halves 25' and 25" and contains a denture model consisting of wax 26 
and artificial teeth 27. Both halves 25' and 25" are filled with plaster 
28 and parting surfaces 29 are provided, as known. 
When the wax 26 has solidified and the plaster 28 has set, the dewaxing 
operation can be carried out: firstly, the wax must be heated to separate 
the flask halves. This is done by filling basin 1 with water and placing 
the flasks 25 on either the middle tray 10 or lowermost tray 11, as shown 
in FIG. 4. When wax 26 is sufficiently hot, the flask halves are separated 
and placed in topmost tray 9. Frame-arm 19 is then pivoted downwardly to 
its horizontal spray position. A contact switch 30 is provided to activate 
pump 23 automatically when abutted by arm 19. (cf. FIG. 5) When all traces 
of wax 26 have been sprayed away by nozzles 20, the flask halves are 
filled with plastic denture material (not shown) and reassembled for the 
final curing step. 
As shown in FIG. 6, the dentures are cured under water in basin 1 for 
predetermined periods of time, for example one hour at 180 degrees F. and 
eight hours at 160 degrees F. Preferably, an automatic timer (not shown) 
is provided to turn on and off the heating element 14 according to desired 
curing periods; a thermostat (not shown) is also provided to maintain the 
curing temperature at constant degree. 
Referring finally to FIG. 5, there is shown the second stage of the 
dewaxing step, as mentioned above. However, it will be clear that curing, 
as well as dewaxing the flasks 25, can be done simultaneously: the flasks 
ready to be cured are placed in either the middle or lowermost trays 10 
and 11 (although none are shown in the figure); the basin is filled with 
water 8 and heating element 14 is turned on; at the same time, flask 
halves, ready for final dewaxing, are placed in topmost tray 9; the 
frame-arm 19 is pivoted to its horizontal position, thus activating the 
pump 23, whereby the flask halves are sprayed clean. It will be clear as 
well that dewaxing and curing can be carried out in consecutive steps, if 
so desired.