Particulate matter delivery device

Disclosed is an improved apparatus for delivery of pressurized particulate matter against a surface or target to abrade, etch, erase, cut, penetrate, smooth, clean, polish and/or harden the surface or target. The most important use to which the present invention is adapted is use by dentists and oral hygienists to very effectively clean teeth, employing a particulate matter such as aluminum oxide, while at the same time having no effect on soft tissue such as the gums. This is accomplished using a prefilled, sealed, and disposable fluidizing chamber and cannula assembly that avoids contamination and which has already been approved by the FDA for dental use. Included is a fluidizing chamber having a discharge end of an inlet tube that is disposed below or overlaps the intake end of the cannula such that the discharge of the inlet tube blows the particulate matter into the fluid above the intake end of the cannula, thereby suspending it therein, without clogging. The invention further provides for a custom designed double acting safety check valve to prevent backflow of particulate matter in the event of a drop in pneumatic pressure, and also to prevent excessive pressure from reaching the fluidizing chamber and cannula in the event of a pressure surge. Another feature of the invention includes a tapered nozzle and optionally bent cannula. The check valve attaches to the pre-existing pneumatic pressure line of a dental office pedestal.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to delivery devices, and in particular to an 
improved apparatus for delivery of pressurized particulate matter against 
a surface or target to abrade, etch, erase, cut, penetrate, smooth, clean, 
polish and harden the surface or target. 
BACKGROUND OF THE INVENTION 
While a number of generalized applications for the present invention are 
mentioned above, one specific use to which the present invention is 
adapted is use by dentists and oral hygienists to clean teeth, 
particularly in preparation to adhere other materials to a tooth, such as 
a filling. The present invention is extremely well adapted to this 
application because it delivers a very effective cleaning capability, 
employing a particulate matter such as aluminum oxide, while at the same 
time having no effect on soft tissue such as the gums. 
The major aspect of the present invention is a prefilled, sealed, and 
disposable fluidizing chamber and cannula assembly that avoids 
contamination and which has already been approved by the FDA for dental 
use. Earlier designs of pressurized particulate matter delivery devices 
have demonstrated there can be difficulty with clogging in the fluidizing 
chamber and/or the delivery tube. The present invention is partially 
directed to an improved internal structure of the fluidizing chamber which 
produces effective fluidization without clogging. It further provides for 
a custom designed double acting safety check valve to prevent backflow of 
particulate matter in the event of a drop in pneumatic pressure, and also 
to prevent excessive pressure from reaching the fluidizing chamber and 
delivery tube in the event of a pressure surge. Another feature of the 
invention includes a tapered nozzle and optionally bent particle delivery 
cannula. The custom designed double acting safety check valve aspect of 
the invention is designed to attach to the pneumatic pressure line of a 
dental office pedestal, operated by a foot pedal. This disposable 
fluidizing chamber and cannula assembly is extremely lightweight and is 
removably connected to the check valve. 
Examples of prior known devices include that described in U.S. Pat. No. 
4,941,298 to Fernwood, which discloses a rear-reservoir micro sandblaster. 
The Fernwood patent has numerous problems including costly to dispose, 
special training for set up and use, cannot deliver varying sizes of 
particles, contaminated after each use, must be completely sterilized 
after each use. Other known devices with similar problems are the 
Microetcher.TM. and the Handiblaster.TM. available from Mirage/Chameleon 
Dental Products, Inc. 
SUMMARY OF THE INVENTION 
The primary object of the present invention is to provide a particulate 
matter delivery device that includes an FDA approved prefilled, sealed, 
and disposable fluidizing chamber and cannula that avoids contamination. 
Prefilling, sealing, and disposability are key aspects to assurances that 
materials used in a patient's mouth are sanitary since the manufacturing 
facility has complete control over the sterility of the inventive device 
and the particulate matter with which it is charged in the manufacturing 
process. 
Another important object of the present invention is to provide a 
particulate matter delivery device that includes an improved internal 
structure of the fluidizing chamber which produces effective fluidization 
without clogging. 
One more important object of the present invention is to provide a 
particulate matter delivery device wherein the prefilled, sealed, and 
disposable fluidizing chamber and cannula assembly is removably connected 
to a custom designed double acting safety check valve, which acts to both 
prevent backflow to the pneumatic pressure line of a dentist's pedestal in 
the event of a pressure drop and also prevents pressure surges from 
reaching the fluidizing chamber, and the patient's mouth. 
A related object of this invention is to provide a particulate matter 
delivery apparatus wherein the custom designed double acting safety check 
valve is removably attached to the pneumatic pressure line of a dental 
office pedestal, operated by a foot pedal. 
A further object of this invention is to provide a device for delivery of a 
fluid particle stream using a cannula with a tapered nozzle to accelerate 
particle velocity. 
An additional object of this invention is to provide a particulate matter 
delivery apparatus that is very lightweight to make it easy for a dentist 
or oral hygienist to use. 
One more object of the invention is to provide an effective, safe, 
sanitary, FDA approved, easy to use dental cleaning device that requires 
essentially no capital investment by the dentist because it employs a 
pneumatic pressure line already found on a dentist's pedestal, uses a 
small lightweight check valve, and a small lightweight fluidizing chamber 
and cannula assembly that is disposable. 
A preferred embodiment includes a fluidizing chamber for mixing fluid and 
particulate matter together by suspending the latter in the former, and a 
cannula tube having a particle accelerating tapered nozzle extending 
outside the fluidizing chamber, wherein the cannula tube delivers 
pressurized particulate matter from the fluidizing chamber to a surface or 
target at a high velocity. 
The fluidizing chamber incorporates a simple yet extremely effective 
internal structure to accomplish the suspension of the particulate matter 
in the fluid, usually air. It is merely comprised of a discharge end of an 
inlet tube that is disposed below the intake end of the cannula or 
overlaps it. Both the inlet tube and cannula tube are preferably insert 
molded into the adjoining members of the fluidizing chamber structure. The 
effect is that the discharge of the inlet tube blows the particulate 
matter into the fluid above the intake end of the cannula, thereby 
suspending it therein, without clogging. 
The members of the fluidizing chamber structure are comprised of a barrel, 
to which the cannula is preferably insert molded, and a barrel end cap, to 
which the inlet tube is preferably insert molded. The barrel end cap 
preferably has internal threads which rotate about and engage mateable 
threads on the top of the barrel of the fluidizing chamber. This structure 
allows, in an alternative embodiment, for the inventive to be recharged 
with particulate matter, but in the preferred embodiment, the fluidizing 
chamber is prefilled, sealed, and disposable. Sealing is accomplished by 
gluing or otherwise preventing relative movement between the mating 
threads of the fluidizing chamber barrel and its barrel end cap after the 
fluidizing chamber has been charged with particulate matter. In the 
preferred embodiment, the manufacture, charging and sealing is all 
accomplished under sanitary conditions because the product is going to be 
used in a patient's mouth. 
Another important feature of the preferred embodiment is the custom 
designed double acting safety check valve which is disposed between the 
prefilled, sealed, and disposable fluidizing chamber and the pneumatic 
pressure line of a dental office pedestal. This check valve primarily acts 
to prevent particulate matter from being drawn back in to the pneumatic 
pressure line in the event of a sudden drop in pressure, but will also 
will seal off the inlet tube into the fluidizing chamber in the event of a 
pressure surge such as may occur with a regulator failure or an 
unregulated runaway compressor. 
One more feature of the invention is the use of a particle accelerating 
tapered nozzle at the discharge end of the cannula. This increases the 
velocity of the particles exiting from the cannula discharge orifice. 
Further objects and advantages of this invention will be apparent from the 
following detailed description of a presently preferred embodiment which 
is illustrated schematically in the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Before explaining the disclosed embodiment of the present invention in 
detail it is to be understood that the invention is not limited in its 
application to the details of the particular arrangement shown since the 
invention is capable of other embodiments. Also, the terminology used 
herein is for the purpose of description and not of limitation. 
FIG. 1 is a plan view of the improved particulate matter delivery device 2, 
having a fluidizing chamber 4, cannula 6, and double acting check valve 8. 
The fluidizing chamber 4 is comprised of barrel 10, and barrel end cap 12. 
Cannula 6 preferably includes a tapered nozzle 14 to accelerate particle 
velocity toward the target (not shown). Cannula 6 terminates, of course, 
with a discharge orifice 16. 
FIG. 2 is a partial cross-sectional view of the improved particulate matter 
delivery device 2 of FIG. 1, showing the interior structure of the 
fluidizing chamber 4. Inlet tube 18 having discharge end 20 is shown 
overlapping the intake end 22 of cannula 6 to achieve the suspension of 
particulate matter in fluid such as air. Since the improved particulate 
matter delivery device 2, when in use, is usually held erect with the 
cannula 6 generally below the fluidizing chamber 4, the particulate matter 
24 will generally then be resting at the cannula end of the barrel 10. It 
is for that reason that the above description refers to the internal 
structure of the fluidizing chamber as having a discharge end of an inlet 
tube that is disposed "below" the intake end of the cannula 6. Check valve 
jaws 30 and valve end cap 12 locking hub end 32 and barrel end cap bulges 
78 interconnect. Cannula 6 is tightly held in barrel aperture 26. It is 
preferably insert molded thereat but also may be glued, press fitted or 
the like. Elsewhere, barrel end cap 12 is shown attached to barrel 10 at 
mateable threads 28. Also seen are double acting check valve 8, check 
valve jaws 30, which interconnect with locking hub end 32 at the top end 
of barrel end cap 12, gasket 34, guide pin 36 and pneumatic pressure line 
connector 38. 
FIG. 3 is a broken cross sectional view of the top end 40 of the barrel 
member 10 of the fluidizing chamber 4 showing the mateable threads 28. 
FIG. 4 is a cross-sectional view of the barrel end cap 12 showing mating 
internal threads 28, for attachment to corresponding threads on the top of 
the barrel, and barrel end cap aperture 42 into which is placed inlet tube 
18 as seen in FIG. 2. Inlet tube 18 is placed in barrel end cap aperture 
42 preferably during the molding process, i.e., is insert molded. 
Alternatively inlet tube 18 may be glued or press fitted into barrel end 
cap aperture 42. Finally, barrel end cap 12 includes barrel end cap flats 
44 as more clearly seen in FIG. 5 and O-ring bearing internal surfaces 80. 
FIG. 5 is a end view of the barrel end cap 12 of the fluidizing chamber 4 
showing the eccentric position of the barrel end cap aperture 42, which is 
necessitated by the overlapping configuration of the inlet tube 18 and the 
barrel concentric cannula 6 as seen in FIG. 2. Also seen barrel end cap 
flats 44, barrel end cap bulges 78, rotation stops 46, and, in phantom, 
mateable threads 28. 
FIG. 6 is a broken view of the barrel 10 showing an alternative embodiment 
of the cannula 6 in a bent configuration that may be preferred by some 
users of the invention. 
FIG. 7 is a side view of the barrel end cap 12 of FIG. 5 showing an 
enlarged lateral dimension of the barrel end cap bulges 78 of the locking 
hub end 32. The barrel end cap bulges 78 interconnect and are tightly held 
as seen in FIG. 2 with the check valve jaws lips 74 disposed on the distal 
ends of check valve jaws 30. 
FIG. 8 is a second alternative embodiment of the cannula 6 with a flared 
intake end 48. 
FIG. 9 is partial cross-sectional view of the double acting check valve 8 
in combination with check valve jaws 30, guide pin 36 and pneumatic 
pressure line connector 38 showing the internal structure of check valve 
8. Double acting check valve 8 is comprised of a check valve housing 50, 
check valve intake manifold 52, check valve intake port 54, resilient 
valve shuttle 56, check valve cylinder 58, check valve biasing means 60, 
floating biasing means retainer 62, check valve housing cap 64, check 
valve assembly retainer 66, check valve discharge port 68, O-ring channel 
70, O-ring 72, check valve jaws 30 and check valve jaw lips 74. Resilient 
valve shuttle 56 may be made from rubber, and check valve biasing means 60 
is preferably a coil spring. 
In operation, air pressure entering check valve 8 passes through pneumatic 
pressure line connector 38 into check valve intake manifold 52. The 
pressure is exerted on resilient valve shuttle 56 which then overcomes the 
resistance of the check valve biasing means 60 and opens the check valve 
intake port 54. The fluid then passes through the check valve cylinder 58 
to emerge through the check valve discharge port 68. 
When the pressure in the pneumatic pressure line connector 38 drops check 
valve biasing means 60 causes the resilient valve shuttle 56 to close off 
the check valve intake port 54 thereby preventing particulate matter from 
backing up into the pneumatic pressure line connector 38. Similarly in the 
event of an excessive pressure surge, check valve biasing means 60 will be 
further compressed and the top surface of resilient valve shuttle 56 will 
be pressed against check valve discharge port 68 thereby preventing the 
pressure surge from reaching fluidizing chamber 4. 
FIG. 10 is an end view of the double acting check valve 8 showing the top 
of the check valve housing 50, check valve discharge port 68, check valve 
jaws 30 and check valve jaw lips 74. 
Interconnection of the check valve 8 with barrel end cap 12 is achieved by 
inserting barrel end cap 12 into the check valve jaws 30 with the barrel 
end cap 12 rotationally oriented so that the check valve jaws 30 are 
adjacent barrel end cap flats 44. When the barrel end cap 12 has been 
fully inserted, the barrel end cap 12 and check valve 8 are rotated with 
respect to each other until the check valve jaws reach the rotation stops 
46 such that check valve jaw lips 74 pass over and fully engage with 
barrel end cap bulges 78. See FIG. 2. Rotation stops 46 also assure that 
rotation is done only in the right direction and stops after there is full 
engagement in a twist and lock configuration. Sealing is accomplished 
because O-ring 72 seen in FIG. 9 comes in contact with O-ring bearing 
internal surfaces 80 as seen in FIG. 4. 
Of course the above procedure is simply reversed when disassembly is 
desired. Therefore, should the prefilled, sealed, and disposable 
fluidizing chamber and cannula assembly run out of particulate matter 
before a cleaning of a patient's teeth is completed, it takes only a few 
seconds to disconnect the discharged fluidizing chamber and cannula 
assembly, dispose of it, and reconnect a prefilled replacement onto the 
check valve. 
While the above embodiments describe using particulate matter such as 
aluminum oxide in the chamber, other particles such as but not limited to 
sodium bicarbonate can be used. Further, the above embodiments can include 
a separate water line running through the interior chamber from a 
conventional outside waterline so that water under pressure can be sprayed 
onto teeth in a cleaning operation while sodium bicarbonate or aluminum 
oxide is also used in combination to clean the teeth. 
Various materials used in the construction of the embodiments include but 
are not limited to plastic, stainless steel, Delrin.TM., and Teflon.TM.. 
Referring to all the above embodiments, various components can be sealingly 
attached to one another by means such as but not limited to ultrasonic 
welding, adhesive bonding, screwing and ratcheting, and sealing by solvent 
welding. 
While the invention has been described, disclosed, illustrated and shown in 
various terms of certain embodiments or modifications which it has 
presumed in practice, the scope of the invention is not intended to be, 
nor should it be deemed to be, limited thereby and such other 
modifications or embodiments as may be suggested by the teachings herein 
are particularly reserved especially as they fall within the breadth and 
scope of the claims here appended and their equivalents.