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Keeping Dental Waterlines Clean
Dental unit waterlines supply the water used during dental treatment. The water is used most often in high-speed drills, the air-water syringe, and the Cavitron® (which cleans teeth and gums). Water both cools and helps clear away debris when a high-speed dental drill is preparing a tooth.
The potential problem with the waterlines is that they become colonized with microorganisms, and develop a biofilm within the narrow tubing. This potential problem has been the subject of serious controversy over the last few years. The question is, is it much ado about nothing?
Normal drinking water is usually allowed to have up to 500 colony forming units (CFU's) of bacteria per milliliter, but is often found to have many times that amount when entering homes due to colonization in the water pipes. Water found in drinking fountains, water coolers and presumably "pure" bottled water have been found to have thousands of CFU's per milliliter.
A glass of water from a kitchen faucet sitting stagnant at room temperature is often teeming with bacteria due to microbial bursts that exponentially increase the numbers of bacteria. The amount of bacteria found in dental unit waterlines varies, depending on the methods used to reduce it.
What most people want to know is, "What is the risk of contracting an infection from the water used in dental treatment?" The risk for getting an infection from the dental waterlines is probably very low, although nobody really knows for sure. People are exposed to potentially high concentrations of bacteria-laden water all of the time from many different sources, so specifically citing the dental waterlines is impossible.
Also, modern dental techniques (e.g., high-speed evacuation of fluids; rubber barrier for treatment; having patients spit the water out during treatment; relatively few visits to the dentist for an average person each year) greatly limit the amount of water patients are exposed to during dental treatment. Research has shown that about 60 milliliters (2 oz.) of water is used for a typical dental visit, and more than 90 percent of that is usually removed (not ingested) using the above methods.
It is also important to remember that the mouth and gastrointestinal tract contain millions of bacteria, many of which are both beneficial and necessary for life. Other bacteria, of course, are associated with infectious diseases and should be avoided. There might be a higher potential risk for a person with a weak immune system (e.g., those that have diseases like AIDS, severe and uncontrolled diabetes, or are being treated with chemotherapy for cancer) when they are exposed to any colonized water, including dental waterlines. The ADA does not cite any documented cases of people contracting dental infections from the waterlines.
The second question people ask is "What methods can dentists take to reduce the bacteria used in dental treatment?" Dentists routinely take many measures to reduce the bacteria in dental water used during treatment:
- Use of high-speed suction to remove water during treatment.
- Having patients spit out excess water during treatment.
- Use of a rubber barrier (rubber dam) for some procedures to prevent water from getting into the mouth in the first place.
- Flushing out water from the dental lines for several minutes at the beginning of each day.
- Running the drill for a half a minute after each use.
- Having proper maintenance of the waterlines.
Other procedures, such as the preparation of crowns (caps) and dental cleanings, cannot be done using a rubber barrier.
Some companies have created products to reduce the bacteria in the waterlines. All of the options have limitations and take time and money to implement:
- Using filters for the water.
- Using chemicals to disinfect the dental lines (e.g., diluted bleach 1:10, glutaraldehyde, food grade ethyl, alcohol, chlorhexidine-based products). These chemicals may be more harmful than the bacteria if ingested.
- Using a combination of ozone and silver ion catalyst to disinfect the dental lines.
The manufacturers of dental units have known about this problem for years and have done nothing about it. Having waterlines supplying the dental unit is a design flaw that these manufacturers should have addressed, but did not. The ADA has encouraged the manufacturers to help solve the waterline problem and has made some suggestions, such as having an independent water supply for dental drills and other equipment.
Dentists may need to take steps to address this potential problem while the public and organized dentistry is urged to put pressure on the manufacturers of dental units to solve the problem that they helped to create.
There are some new products on the market that have tested well and may eliminate nearly all bacteria from the lines. In my office, I filter the water and use ozone, coupled with silver halide catalyst, to disinfect the dental lines. Dentists will continue to safeguard the well-being of their patients while encouraging the dental unit manufactures to create dental units that address the waterline issue.
The ADA recommends that all water used in dental treatment have a maximum of 200 CFU's per milliliter (the standard used in kidney dialysis).
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