| United States Patent Application |
20020148789
|
| Kind Code
|
A1
|
|
Layton, Grant H.
|
October 17, 2002
|
Clean water for dental delivery units
Abstract
A method of producing Clean Water for Dental Delivery Units is described
using colloidal silver to sanitize the water supply of dental water
delivery units. The silver compound is generated by means of a
proprietary process contained in a U.S. patent application. The Clean
Water for Dental Delivery Units method is capable of delivering sterile
water to dental patients from existing equipment with complete safety for
patients and dental office staff.
| Inventors: |
Layton, Grant H.; (Carlsbad, CA)
|
| Correspondence Name and Address:
|
DAVID R PRESTON & ASSOCIATES
12625 HIGH BLUFF DRIVE
SUITE 205
SAN DIEGO
CA
92130
US
|
| Serial No.:
|
792339 |
| Series Code:
|
09
|
| Filed:
|
February 26, 2001 |
| U.S. Current Class: |
210/748 |
| U.S. Class at Publication: |
210/748 |
| Intern'l Class: |
C02F 001/467 |
Claims
What is claimed is:
1. A method for limiting the growth of microbial films in the water
delivery lines of dental offices which comprises the steps of generating
a stable silver solution and then adding a specified amount of said
solution to water in dental office water reservoirs.
2. The method as claimed in claim 1 where said stable silver solution is
generated by electrolytic means.
3. The method as claimed in claim 1 where said stable silver solution is a
solution of multivalent silver.
4. The method as claimed in claim 3 where said stable silver solution is
generated by electrolytic means.
5. The method as claimed in claim 2 where no inline microbial filters are
used in said water delivery lines to eliminate bacteria.
6. The method as claimed in claim 4 where no inline microbial filters are
used in said water delivery lines to eliminate bacteria.
7. The method as claimed in claim 2 where no periodic chemical flushes are
used in said water delivery lines.
8. The method as claimed in claim 4 where no periodic chemical flushes are
used in said water delivery lines.
9. The method as claimed in claim 2 where said stable silver solution will
not stain skin or surfaces with which it comes in contact.
10. The method as claimed in claim 4 where said stable silver solution
will not stain skin or surfaces with which it comes in contact.
11. The method as claimed in claim 2 where said stable silver solution is
light stable and shelf-life stable.
12. The method as claimed in claim 4 where said stable silver solution is
light stable and shelf-life stable.
13. The method as claimed in claim 2 where said water delivery lines are
neither autoclaved nor dried before or after use.
14. The method as claimed in claim 4 where said water delivery lines are
neither autoclaved nor dried before or after use.
15. The method as claimed in claim 2 where the lumens of said water
delivery lines are coated by said stable silver solution, and microbial
colonization is thereby further inhibited.
16. The method as claimed in claim 4 where the lumens of said water
delivery lines are coated by said stable silver solution, and microbial
colonization is thereby further inhibited.
17. The method as claimed in claim 2 where the water in said water
delivery lines can be heated without increasing microbial colony counts.
18. The method as claimed in claim 4 where the water in said water
delivery lines can be heated without increasing microbial colony counts.
19. The method as claimed in claim 2 where bacterial growth in the
downstream vacuum system of dental units, including hoses, traps, and
valves is eliminated.
20. The method as claimed in claim 4 where bacterial growth in the
downstream vacuum system of dental units, including hoses, traps, and
valves is eliminated.
21. The method as claimed in claim 2 where the water in said dental
delivery lines is non-toxic, has no taste, and has no smell.
22. The method as claimed in claim 4 where the water in said dental
delivery lines is non-toxic, has no taste, and has no smell.
23. The method as claimed in claim 2 where no changes are required to
existing dental office water delivery hardware.
24. The method as claimed in claim 4 where no changes are required to
existing dental office water delivery hardware.
25. The method as claimed in claim 2 where the water in said dental
delivery units can remain stagnant without becoming foul smelling or bad
tasting due to bacterial growth.
26. The method as claimed in claim 4 where the water in said dental
delivery units can remain stagnant without becoming foul smelling or bad
tasting due to bacterial growth.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to dental equipment
hygiene. More specifically, the present invention pertains to the
employment of
colloidal silver as a bactericide for water storage and
delivery equipment used in dental offices.
[0002] The present invention is particularly useful for safely preventing
microbial growth in dental delivery unit water lines. Microbial growth in
dental water delivery lines has been identified as a significant problem.
[0003] Methods have been devised and are being sold to sanitize the lines.
They are all subject to failure. Mechanisms can fail and allow bacteria
to grow, and bacteria grows back between chemical flush sanitations, and
where filters are used, bacteria grows back between the filter and the
outflow.
[0004] Current sanitization technologies include purging and flushing
systems, and protocols, back-flow preventers, ultraviolet water
purifiers, heat sterilization of lines and units, and water filtration
with sub-micron particulate filters.
[0005] To date, there have been several patents claiming uses for a
multi-valent silver colloid produced by chemical or electrolytic means.
U.S. Pat. No. 5,223,149 in particular describes the use of tri-valent
silver colloid generated by chemical means, such as reacting Ag(III)
tetrasilver trioxide with a ligand bearing compound capable of forming
Ag(III) complexes, or other chemical means. U.S. Pat. No. 5,017,295
describes a multivalent silver bactericide used in swimming pools. The
present invention uses a
colloidal silver solution created by
electrolytic means, in a process applied for in patent application Ser.
No. 09/323,310, filed Jun. 1, 1999.
[0006] The present invention constitutes a substantial improvement in
water hygiene technology for dental offices, over the existing
technologies listed above.
BACKGROUND OF THE INVENTION
[0007] Microbial growth in water delivery lines is a persistent problem in
the dental environment. Typically, dental water delivery units contain
small-diameter water supply tubings that carry water to rinse the
patient's mouth during dental procedures. Because their inside diameters
are approximately 1 millimeter and are made of flexible silicone or other
plastic, these water tubings are excellent environments for the
development of microbial biofilms. The biofilms shed into the water
supply, pose a health risk to dental patients and the office staff, and
the microflora also cause foul odor and bad taste in the water. The water
containing the bacterial growth is typically sprayed into the patients
mouth during dental procedures and the aerosol can be inhaled as well as
contacting broken skin.
[0008] In light of the above, there is a need for a clean water system for
dental office equipment. Accordingly, it is an object of the present
invention to provide a dedicated water system for dental office equipment
that is essentially sterile. A dedicated water supply in this instance
means water from a pressurized canister, not tap water.
[0009] It is another object of the present invention to provide the
cleanest water system for dental water delivery units which is low-cost
and easy to install and maintain.
[0010] It is another object of the present invention to use the
antimicrobial medium that has the least possibility of deleterious
interaction with patient or dental equipment.
[0011] It is another object of this invention to eliminate the need for
and use of inline microbial filters to eliminate bacteria in the water,
and periodic chemical flushes, autoclaving or drying of the lines to
remove biofilm that grows on the inside of the water lines.
[0012] It is another object of this invention to provide a product that
will be shelf stable.
[0013] It is a further object of this invention to permit warming the
water while discouraging the growth of pathogenic organisms in dental
water lines.
[0014] It is a further object of this invention to provide a solution that
gradually coats the lining of dental water unit tubing with silver and
thereby further discourages the growth of microbial colonies.
[0015] It is another object of this invention to improve the cleanliness
of the vacuum system, vacuum traps and sewers in dentists' offices.
[0016] It is another object of this invention to provide water that has no
taste or smell.
[0017] It is a further object of this invention to achieve the above
objects of this invention without requiring changes to dental office
water delivery hardware.
SUMMARY OF THE INVENTION
[0018] In accordance with the present invention, Clean Water for Dental
Delivery Units, dental patient and office staff health and safety will be
assured by the addition of
colloidal silver to the dedicated water supply
of dental delivery units. The Clean Water for Dental Delivery Units
invention may be used to safely treat the water supply of dental delivery
units to reduce bacterial growth within said water supply.
[0019] The Center for Disease Control (CDC) and the American Dental
Association (ADA) have called for manufacturers of dental equipment to
provide dental delivery units that will deliver water at less than 200
colony forming units (CFU's), measured by bacterial growth on a culture
plate. There are existing methods to sanitize Dental Unit Water Lines
(DUWLs); they are all subject to failure. Mechanical means can fail and
allow bacterial growth, and bacteria will grow past filters and back up
the waterlines from point of exit.
[0020] The US EPA has established an RfD (Reference Dose) for silver of
0.005 mg/kg of body weight/day. The Reference Dose is the amount that the
most sensitive individuals may ingest every day over a 70 year lifetime
without likelihood of harm. A 70 kg (154 lb) patient may ingest 0.350 mg
of silver each day without exceeding the RfD. This is equivalent to 35 ml
of the Ag3p concentrate, or 700 ml of the treated water. In a study done
in 1999, rats given a dose of the Ag3p concentrate equal to 11 g/kg of
body weight suffered no ill effects (the equivalent dose in a 70 kg human
would be 770 ml of the concentrate, or 15.4 liters of treated water). In
a 1968 study cited by the EPA, under controlled conditions researchers
caused rats to ingest silver at 28,000 times the RfD (140 mg/kg/day) and
reported that it was "well tolerated". The EPA does not currently have a
drinking water standard for silver. It does publish a secondary
(non-enforceable) standard of 0.1 mg/liter based on the RfD. When diluted
20:1 as directed, the Ag3p treated water delivered to the patient will
contain silver at 0.5 mg/liter. A typical dental patient will be exposed
to 50-200 ml of this water on each visit, with almost all of this being
suctioned away before it can be ingested. If the dentist uses 200 ml of
water on a patient, and the patient swallows 10% of it, or 20 ml, that
patient will have ingested only 0.010 mg of silver. This is a negligible
amount compared to even the very conservative RfD.
[0021] The Clean Water for Dental Delivery Units will be immediately
applicable to existing DUWLs in all dental offices without retrofitting
of said lines. The present invention can be applied to either de-ionized
tap water or distilled water with the same beneficial effect.
[0022] The silver solution of this invention is simple and cannot fail
because it is simply added to the water in a dedicated water supply
system. It is non-toxic, with no taste, and provides pure water that is
basically sterile.
[0023] As an added bonus, the downstream sewer is cleaner. What used to be
a foul, stinking job of cleaning the "trap" below a dental unit is now a
relatively clean experience. This means that the vacuum lines are also
free of bacteria.
[0024] The
colloidal silver used by this invention is created by a
proprietary, high-voltage electrolytic process as opposed to the current
state of the art, which involves either chemical production or
low-voltage production.
[0025] Said
colloidal silver used in this invention was evaluated by the
inventor as to its anti-microbial capabilities. The results of these
evaluations are shown in Tables 1, 2, and 3.
[0026] Note: TNTC in tables below is defined as "Too Numerous To Count"
1TABLE 1
Bactericidal and Bacteristatic Effect of
Ag3p on Contaminated
Dental Unit Water Effluent
Ag3p
Treatment Test Date CFU/ml
Pre-Treatment 1/31/2000
15,200
Treatment Initiated 2/15/2000
10 ppm 2/16/2000 0
1 ppm 2/25/2000 0
0.5 ppm 3/23/2000 0
0.5 ppm
5/11/2000 0
0.1 ppm 6/14/2000 0
[0027]
2TABLE 2
Maintain Dental Unit Effluent Sterility by
0.25 ppm Ag3p
Ag3p Treatment Test Date CFU/ml
Pre-treatment 4/29/2000 TNTC
Treatment Initiated 5/7/2000
2 ppm 5/8/2000 TNTC
1 ppm 5/9/2000 0
0.5 ppm
5/11/2000 0
0.25 ppm 6/14/2000 0
[0028]
3TABLE 3
Induction of Dental Unit Sterility by 0.25
ppm Ag3p
Ag3p Treatment Test Date CFU/ml
Pre-Treatment 6/5/2000 TNTC
Treatment Initiated 6/5/2000
0.25 ppm 6/6/2000 TNTC
0.25 ppm 6/7/2000 1610
o.25 ppm
6/8/2000 81
0.25 ppm 6/12/2000 160
0.25 ppm 6/13/2000 8
0.25 ppm 6/14/2000 10
0.25 ppm 6/21/2000 2
0.25 ppm
6/22/2000 16
[0029] Table 1 illustrates that treating effluent dental water with 10 ppm
of Ag3p initially brought the Colony Forming Units per milliliter
(CFU/ml) of bacteria count down from 15,200 to 0 (zero) in one day. The
maintenance levels of 1.0 and then 0.5 ppm of Ag3p kept the water
sterile. A level of 0.1 ppm was not sufficient to maintain dental water
sterility.
[0030] Table 2 shows that after treating effluent dental water with
initially 2 ppm for one day, then 1 ppm of Ag3p on the second day, water
was made sterile. Effluent water was kept sterile for one month by
maintaining a 0.25 ppm level of Ag3p, once the CFU/m count had been
brought down to 0(zero).
[0031] Table 3. shows that introducing a level of 0.25 ppm of Ag3p into
dental effluent water would drastically reduce but not completely
eliminate bacteria CFU's. Bacteria were never eliminated from the lines
completely, indicating that 0.25 ppm Ag3p was sufficient to maintain but
not to achieve sterility. defined as 0 CFU/ml.
[0032] As a consequence of these tests, the colloidal solution is being
registered with the EPA, which has accepted it for evaluation. Test
results by the inventor have shown that the solution eliminates all
microbial growth in dental equipment at concentrations of 0.5 ppm and at
as low as 0.25 ppm.
[0033] EPA tests have shown that the solution is safe for human
consumption at much higher concentrations than those that patients would
be exposed to in a dental office. The proprietary silver solution is
light stable, non-staining, and does not interact with dental equipment.
BRIEF DESCRIPTION OF THE FIGURES
[0034] FIG. 1 shows a typical arrangement of dental office water lines,
vacuum systems, and sewers.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0035] The silver colloid produced by a Patent Pending method of
manufacture consists of minute, uniformly colloid sized (median diameter
less than 0.01 micron) particles of metallic silver. Most of these silver
particles are coated with various silver oxides, including multi-valent
oxides. In addition to helping the product to be extremely shelf stable,
these oxides allow the formation of small numbers of multi-valent silver
ions (Ag+2 and Ag+3) which are many times more effective at killing
microbes than Ag+1 ions.
[0036] It is recommended that the colloid be diluted with distilled or
de-ionized water. Distilled water is easily and inexpensively purchased
locally, or it may be produced by a small in-office distiller. It
provides a consistent quality and keeps the dental unit clean and free
from contamination.
[0037] The subject solution is designed to be used with a closed (bottle
type) dental water delivery system. Each time the bottle is refilled, a
specific amount of the silver solution is added.
[0038] Referring to FIG. 1, a typical closed dental water system has a
input for pressurized air 1, a water bottle 2, and a pressurized water
output 3 that leads to both the dental drill 4 and syringe 5. The silver
treated water is added to the water bottle 2 as needed and supplies the
illustrated devices. Used water is accumulated by the high-volume vacuum
9 and low-volume vacuum 10 and at the cuspidor 11. The accumulated water
is passed through the vacuum line 8 by pressure from the vacuum 6,
through the vacuum trap 12 and filter 7. The water ends up in the dental
water sewer.
[0039] While the Clean Water for Dental Delivery Units of the present
invention as herein shown and disclosed in detail is fully capable of
obtaining and providing the advantages herein before stated, it is to be
understood that it is merely illustrative of a preferred embodiment of
the invention and that no limitations are intended to the details of
construction or design herein shown other than as described in the
appended claims.
