Michael C. Goldman, DDS

Dental Equipment Safety

The "Biofilm" issue

Bacterial Water Supply Contamination

You may not have heard about it yet, but the newest wave of scary news about the dangers of going to the dentist is coming to the mass media in your neighborhood sometime soon!

It is about concern over the finding that bacteria from the public water system multiply inside dental and medical equipment to a level that is much higher than desired. It has only been noted and documented recently. The results of studies have been a surprise and many of us in dentistry are concerned about it. While there has never been a documented case of anyone getting sick from it, we need to acknowledge that the public water supplies are only getting dirtier and more contaminated, so if the problem is magnified inside dental and medical equipment, we may have a problem just waiting to happen.


Public water supplies are known to have bacteria and other forms of contamination. Municipalities struggle to maintain them within "safe" limits. When this water arrives at your house it should still be within these "safe" limits. When water is routed through the water pipes in your home, the bacteria collect on the inside of the pipes forming a sticky layer rich with bacteria. The water flows past this "Biofilm", as it is called, and everything seems to work out pretty much ok. Inside dental or medical equipment it works a little differently.

Dental equipment has a complex system of tiny plastic tubings that carry water to spray while the high-speed drill or the air/water sprayer are being used. The problem has to do with these tiny plastic water tubings. In your house water-pipes, the pipes are large enough inside that the water can flow in the middle of the pipe space without disturbing the Biofilm . In tiny tubing, as in dental equipment, the physics of the water flowing is such that the flowing water is restricted by the Biofilm, resulting in parts of the Biofilm breaking loose and entering the water flow. The bacteria have been multiplying like crazy in the Biofilm so the resultant water contamination is significant.


The surprising research

At first, researchers thought that this was a problem only in old equipment...old equipment that wasn't kept clean. Then it was thought that the contamination was from patients' saliva somehow backing up or getting sucked back into the equipment.

Now we know that if we take new - or newly disinfected - dental equipment and just run municipal water through it, without ever using it on any patients, it is only a matter of days before the water coming out will be many, many times more contaminated than the water system supplying it. Bacteria can mutate, or change, so it is even possible to find bacterial forms coming from the equipment that are not seen in the supply water.


So what can be done

Presently, many scientists are researching this problem to find practical solutions, or to determine that it is not something to worry about ( not very likely, in my opinion...). The University of Maryland Dental School's Microbiology department is just one of several working on it currently (May, 1996).

One solution to the problem seems to be to disinfect the inside of the equipment regularly and frequently...perhaps even daily. The problem is that this can be a complicated and expensive and time-consuming job, so it may not be practical in a normal private practice setting. Realistically,.... it just wouldn’t get done!

Another solution is to disconnect from the public water supply altogether and after disinfecting the equipment thoroughly run only bottled water that is known to be free of bacterial contamination. Unless some chemical agent is added to that bottled water, however, there will be the possibility of re-contamination over time. To accomplish this, special modification of the equipment is necessary and extra time and expense to maintain it. Even more trouble and expense if the system's cleanliness is to be monitored by a biological laboratory.


What I have done

When I first became aware of this potential problem, I felt I would like to do something proactively about it. I didn't want to be in the position of having to make excuses when asked about it. When I looked around, however, I found there were no definite answers.

In April 1996, I designed and built a "closed water system" for my office, which simply means a way of disconnecting from the public water system and using only bottled water. University of Maryland was interested in my progress and monitored it for a few years. It worked well until Sept. 2000, but was a lot of work to maintain. When I discovered that sometimes the bottled water was NOT FREE OF BACTERIA I decided to try a different approach.

In Sept. 2000 I designed and installed a new system using an ultra fine filter (0.2microns) to keep out bacteria, a carbon filter to remove  chemicals and odors, and an Ultraviolet light filter to kill any bacteria just in case they get through.  It has been working great. 

You can get info on filters and systems and prices at www.pwgazette.com . I purchased my system from them.  Gene will help you if you need help.  Tell him I sent you.  I never met him but we have spent a lot of  time on the  phone and I learned a lot  from him.


Using this system is only a minor inconvenience and expense for me to maintain, but I am pleased to be able to have it for my patients. As I learn more, I'll update this pamphlet to keep it current.

I hope this has been informative and interesting as well!   Let me know!

2011 [to now] update:

While the above system worked well for a long time, what I saw was that the closed-bottle system first used, and the multi-filter system used later, all had a maintenance problem.  They would  become  contaminated after a while so they had to be flushed out and disinfected from time to time.  Even though the water quality was very good, it  worried me that it was still inconsistent. 

Fortunately, the profit-motive has stimulated  several inventions to become available to deal with  water contamination and biofilm prevention.  Each system  has it's own features and advantages and disadvantages.  But it  does seem like there should be more consistency with less need for constant maintenance.  I now use a series of filters to clean up the municipal water and then  I run it through a special filter unit that further cleans and also "medicates" the water with 2 to 6 parts per million Iodine to prevent bacterial growth in the waterlines. 




This pamphlet was written in the hope that it will increase understanding about a topic that seems important from time to time. Obviously it is only part of the whole story, so if you have questions after reading this please do not hesitate to ask or call. Also, if there is a topic that you think would be helpful, please suggest it.


Michael C. Goldman, DDS
General and Cosmetic Dentistry
3815 East-West Highway
Chevy Chase, Maryland 20815 Phone (301) 656-6171



Holism in dentistry is an approach to dental treatment, primarily  caring for  patients' health and safety from both a conventional as well as  "alternative healthcare" point of view.   It is sometimes called "biological" dentistry or "biocompatible" dentistry.  In it's fullest sense, I believe it   acknowledges and deals with  the mind, body and spirit of the patient, not just his or her "teeth".  See Topics / Info.....

Cosmetic dentistry is about doing   quality , esthetic dentistry in a way that looks natural to begin with, and furthermore,   can even  improve  one's  attractiveness through techniques such as bonding, bleaching, veneers, caps, implants and more.  It can   be like "instant orthodontics" in correcting  crooked, twisted or misplaced teeth in many instances.  Dark or misshapen teeth can be restored.   Smiles that lack youthful vigor or beauty can be revitalized! See Topics / Info..

Bleaching, veneers, bonding, caps, bridges, and implants  are cosmetic dentistry treatments that are also  discussed in  Cosmetic Dentistry, and more...