July 1, 2001
by R.A.Clappison, DDS, FRCD(C), FACD
Read a magazine, newspaper or watch television and you are almost certain to come across an article on the quality of drinking water. It is a pressing concern and rightly occupies a priority position in the public’s agenda. Contamination of Dental Unit Water Lines does not occupy the same position with patients because they are not as aware of the problem. The dental profession is becoming more knowledgeable but has yet to pick up the challenge of improvement in a major way. The need was well enunciated in the statement from an IADR abstract “Conscience would dictate that steps be taken to improve the quality of water.”1
Reinforcement of previous knowledge is a recognized teaching aid. The best information in a few words is found in information gleaned from OSAP “Dental Unit Waterline: Check Your Dental Unit water I.Q.”2
“Dental Unit Waterline Biofilm Formation
Microbes enter the tubing from incoming water and to a lesser degree from dental clients during treatment.
The microbes have the ability to adhere to surfaces and to the inside walls of dental tubing within hours.
The attached microbes begin to multiply and start to form a spreading film on the tubing walls.
Additional microbes from the incoming water continue to attach and multiply.
Microbes produce polysaccharide that coats the cells forming a slime layer.
Within a few weeks, the biofilm has covered most of the inside walls of the tubing.
Microbes are continuously released from biofilm into the flowing water.
Conditions that Facilitate Biofilm Formation in Dental Unit Waterlines
Low numbers of microbes are continually entering the tubing.
Nutrients are continually being supplied in the incoming water.
Stagnation of the water in the tubing facilitates accumulation.
The water’s natural flow rate is low near the tubing walls.
Water in the tubing is not under high pressure.
The tubing’s smaller diameter creates a large surface-to-volume ratio.”
These simply stated principles help one understand the formation of Biofilms in dental unit water lines but the problem is how do we control or eliminate biofilms? The most widely agreed upon system seems to be the closed end system. However a closed end system in itself is of little value unless some germicidal treatment is a part of the regimen.
Scientists feel that almost all dental units which accept public utility water, and who do not treat the water or use point-of-use filtration, exceed the 200 CFU/ml ADA guidelines. When one starts correcting contaminated waterlines there is not much sense monitoring the bacterial count until corrective procedures have been completed. The proper handling of reservoir bottles and filters is essential. Improper hand cleansing and handling can contaminate the system with enteric and skin bacteria.
Fortunately there are chemical agents that can successfully reduce biofilms and meet the required criteria of 200 CFU/mL. All chemical agents do not have 510(k) approval numbers but there are some excellent, non -corrosive agents such as Bio 2000 (K925378) and Sterilex Ultra (K991946). There are currently over 20 products available and passed for distribution by the U.S.Food and Drug Administration (FDA).
The thrust of this article from this point will be on a specialty cleaner for Dental Unit Waterlines (Sterilex Ultra). It is an alkaline peroxide based powder with a patented phase transfer catalyst technology. This allows the product to penetrate and remove films and related products. It’s advantages are:
1. Patented phase transfer technology;
2. Dual solubility – both lipid and water soluble;
3. Double Action – both an oxidizer and powerful hydrolyzer.
Sterilex Ultra, to this point, is the first and only DUWL cleaner to earn the American Dental Association’s Seal of Acceptance which states “Sterilex Ultra Powder/Liquid is Accepted as being safe and effective for cleaning deposits and controlling aerobic, mesophilic, heterophilic bacterial contamination in dental unit waterlines when used as directed.”
It is claimed to remove films and deposits and to be non-corrosive, non-toxic, and has a pink dye indicator. After initial treatment it is a once a week treatment creating the verbal logo “Think Pink Once a Week.” It has no odor or foaming capability and is A-Dec recommended. It is cost effective, costing about CD$3.00 per operatory per week and less in multiple operatories.
Sterilex Ultra breaks down biofilms in a three-prong attack. First it attacks and bombards the bioflm. Then it penetrates the outer layer and enters into the matrix and starts to dissolve the matrix. Thirdly it destroys and eliminates the biofilm by a combination of oxidation, hydrolysis and solubization.
With the current concern about residual chemicals in the dental unit waterlines after chemical treatment, the claim of non-toxicity is a positive factor. The estimated safety factor means that if a 50 kg adult patient swallowed an entire mouthful of Sterilex Ultra the factor for reaching the Acute Oral LD5oRAT would be 67 mouthfuls and 133 mouthfuls for a 100 kg adult.
The procedure is time efficient in that, after the initial start-up, the DUWL need only be treated one night a week. The initial start-up requires treating DUWL’s for three consecutive nights.
The procedure is:
1. At the end of the workday, add 8 ounces of hot water to an empty external dental unit water container. It is recommended that only thick-walled bottles be used.
2. Add one packet of Sterilex Ultra to the hot water and swirl to dissolve the powder.
3. Run Sterilex Ultra solution through the system until the pink solution appears out of the air/water syringe and the handpiece lines. Always remove the handpiece and coupler.
4. Allow the Sterilex Ultra solution to remain in the unit overnight.
5. At the beginning of the next workday, discard remaining Sterilex Ultra solution. Rinse the external container with hot water.
6. Fill container with hot water. Flush each line (air/water syringe, handpiece lines) for at least 2 minutes.
The protocol of a once weekly treatment is one that is easily scheduled and followed and is effective.
A study at the UCLA 3 compared Bleach (1:10) with Alkaline Peroxide over a course of 12 weeks. Microbial Analysis was performed to determine the HPC. A section of A/W syringe tubing was viewed under SEM at the start and at the end of the study.
The Sterilex Ultra protocol consistently controlled the CFU count to nearly undetectable levels for 15 days. Microorganisms started to appear in the samples 15 days post-Sterilex Ultra treatment.
Sterilex Ultra effectively and safely maintained dental unit waterline quality that met or exceeded the ADA goal of 200 CFU/mL. when used once per week.OH
Bob Clappison is Oral Health’s board member for Infection Control and Health Issues.
Oral Health welcomes this original article.
1.Epstein J., Dawson J.R., Biuvids I.A., Wong B.: Abstract IADR: The Effect of Bio 2000 on Dental Unit Water Lines.
2.Dental Unit Waterlines: Check Your Dental Water IQ: Helene S. Bednarsh, RDH MPH, Kathy J. Eklund RDH, MPH and Shannon Mills, DDS – reprinted from Access, Vol. 20, No. 9, Copyright 1997 by the American Dental Hygienists Association.
This resource was reprinted with permission of OSAP. OSAP is a nonprofit organization, which provides information and education on dental infection control and office safety. For more information call 1-800-298-6727
3.Bleach Protocol vs. Alkaline Peroxide Product in controlling DUWL Biofilm – Lee T.K., Waked E.J., Wolinsky L.E., Mito R.S., (UCLA School of Dentistry), Danielson R.E., (Bio Vir Labs Inc.)
Disclaimer: The author does not have, or never has had, any financial interest in the product or company discussed and has received no benefits, whatsoever. (rac)