Medicine For People!

July 2018: Your Teeth Vs. Biofilms

Your Teeth versus Biofilm

  • Contents
    • Biofilm
    • Plaque and Tooth decay
    • Daily Teeth Cleaning
    • Next Month


if you wish to take good care of your teeth, you need to know about biofilm. [here’s the Wikipedia Article] The plaque on your teeth is a form of biofilm. It is responsible for tooth decay and tooth loss. 

To understand biofilm, first consider our usual conception of bacteria.  We don’t normally think of them as community organisms, but they are.   Sometimes they can float around independently as in these Bacteroides fragilis commonly found in the human intestine, illustrated below:

These shown are deposited on a glass slide. The clumps are as accidental as seeds sown on bare soil.

More often, bacteria congregate. In so doing, they form the slime that grows on the rocks in the stream, the bottom of a boat, the drain in your sink, or (sorry!) your teeth.  We call these organized communities of bacteria a biofilm.

That’s right.  The bacteria in your mouth are most happy sheltering on the surface of your teeth in a biofilm. 

The Staphylococcus bacteria pictured below are forming a biofilm: they have secreted a film-like material that connects them to each other and to a surface.  This extracellular matrix protects them from antibiotics and from white blood cells and other elements of your immune system; protects them from physical hazards such as drying out; and helps support the growth of other bacteria.  Once within a biofilm, the individual bacteria change their metabolism in a way that makes them even more persistent. 

This example of biofilm happens to have formed on a urinary catheter.  The only way to get rid of the biofilm is to replace the catheter.

Biofilm can form on a tooth and on any human-made thing we put into the human body, be it a heart valve, an artificial joint, a catheter or a pacemaker.  This can lead to local or disseminated bacterial infection and loss of the affected piece of medical hardware. 

Biofilms can have beneficial effects as well, briefly alluded to in the Wikipedia article, but you don’t want to ignore what biofilm can do to your teeth.


You need to understand biofilms to understand care of your teeth.  Once the biofilm has established itself, it begins to grow.  It attracts food debris, other bacteria, and minerals.  Within days it forms something you can see and feel on your teeth: plaque.  Plaque is impossible for you to remove on your own.

 After a while, the bacteria in the plaque alter their metabolism in a way that removes the minerals from your teeth.  No minerals means no strength, no resistance to physical stress, and a wearing away of the enamel.  This, we call tooth decay.

Daily Teeth Cleaning

If you clean that biofilm-to-be off each day, you can largely prevent tooth decay. 

One fundamental tool to remove plaque is a soft bristle brush.  It can take a minimum of 10 minutes a day, just once a day, to remove the plaque.  You may wish to use disclosing tablets to see how well you are doing.  A thoroughly cleaned tooth feels completely smooth to the tongue, as you will discover after getting your teeth cleaned and by keeping them clean.  Having viewed several online videos, this strikes me as the clearest and most correct:

And here is my favorite instruction video about flossing:

Finally, some of you will benefit from an interdental brush, as illustrated here and here.   These clean between the teeth and come in different sizes to match the varying spaces between your teeth.

There could well be other or better brands, but my dentist recommends the G-U-M Summit soft brush and drTungs Smart Floss.  I see no difference between the available brands of interdental brushes.

Next Month

Other measures to combat biofilm!

Thanks to Sarah McMonigle, Registered Dental Hygienist at Dr Scharf’s office, for teaching me how to properly take care of my teeth!

Image sources:



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Medicine for People! is published by Douwe Rienstra, MD at Port Townsend, Washington.