An update on biofilm

April 1, 2002
Engineers, not dentists or hygienists, are responsible for changing our view of bacterial plaque. Here's an update on the latest research.

Engineers, not dentists or hygienists, are responsible for changing our view of bacterial plaque. Here's an update on the latest research.

By Trisha E. O'Hehir, RDH, BS

Have you ever seen this patient? She has repeated sessions of oral hygiene instructions and she hasn't made a dent in reducing her plaque levels with home care. So, you continue to scrape off a big glob of the "white sticky stuff" and show it to her, fully expecting her to finally get the picture! Instead, she says, "I'm sorry, I had a doughnut on the way to work this morning and didn't have time to brush!" She still thinks white sticky stuff is food, and pays no attention when you try to tell her that it is millions of bacteria, encased in slime, living in her mouth. It's too scary to think of millions of bacteria – better just to think of it as doughnut dough!

Plaque has long been thought of as "white sticky stuff," and not just by patients like the one described above. Now, engineers at Montana State University have changed all that. Yes, engineers, not dentists or hygienists! Engineers are responsible for changing our view of bacterial plaque.

I first discussed the work of Dr. Bill Costerton in a column titled: "Learning More About "Plaque City" in the January 2000 issue of RDH. The information in the column was based on a "Dental Plaque Revisited" conference on oral biofilms in health and disease, held in London in November 1999. Those attending called it the "Slime" conference in honor of the polysaccharide slime produced by the bacteria to form biofilms, better known to us as plaque.

In January of this year, Philips Oral Healthcare (new owners of the Sonicare toothbrush) sponsored a symposium for opinion leaders in dentistr, titled: "Emerging Trends in Oral Care." The symposium featured Dr. Costerton and his colleague, Dr. Paul Stoodley, both from Montana State University Center for Biofilm Engineering.

This symposium focused on dentists, but a dental hygienist symposium is planned for the future. Doing more with hygienists is one of the business objectives for Philips Oral Healthcare in 2002. In fact, Dr. Joel Berg, vice president of clinical affairs at Philips Oral Healthcare, has dedicated 2002 as the "year of the hygienist" at Sonicare. Read up-coming issues of RDH for these developments.

Here are a few highlights of the latest in biofilm research:

  • Mushroom-like micro-colonies we call bacterial biofilms consist of one-third bacteria and two-thirds of a slimy, gooey substance secreted by the bacteria to absorb water and trap small particles.
  • Phagocytes and antibodies work well against planktonic (floating) bacteria. Microbiologists have focused on these single cells for so long, they are only now realizing how intricate and complex bacterial biofilms really are.
  • Antibodies actually create a crust around biofilms, preventing antibiotic penetration. Phagocytes become frustrated, and release lots of enzymes that don't penetrate the biofilm ... and in fact, cause damage to surrounding tissue.
  • Studies using a vaccine to enhance antibody production (not in a dental biofilm) did not slow biofilm growth.
  • To penetrate a biofilm, antibiotic concentrations may need to be 1,000 to 1,500 times stronger than those currently used! Why are these bugs so resistant? Take penicillin as an example. Biofilms contain cells that produce beta-lactamases – enzymes that break down the penicillin faster than it can diffuse into the biofilm. If the penicillin reaches an area of the biofilm where bacteria are starved of an essential nutrient, the bacteria may be alive, but not replicating. Penicillin works by attacking replicating bacteria. If the bacteria are alive and not replicating, they may survive exposure to the penicillin.
  • Instead of using chemicals to kill bacteria in a biofilm, research is focusing on physics, using electrical current.
  • Researchers found that red algae in Botany Bay in Australia were rarely covered with biofilms. They identified plant chemicals called furamones that prevented biofilm attachment. That substance now is used in pipes and ship hulls to prevent biofilm formation. Maybe one day we will see a similar substance put in chewing gum to prevent plaque from attaching to the teeth.
  • Shear forces are those of fluid movement around a biofilm. Biofilm formed in higher shear forces is stronger.

Attendees at the January 2002 symposium included approximately 70 dentists from around the world. A few hygienists also were included, and I was thrilled to be part of the group. Other hygienists attending were Sue Skinner, president-elect of the British Dental Hygiene Association, Ann Nabor, president of ADHA, and Annette Ashley-Linder, a speaker and consultant from Virginia. Annette and I also are advisory board members. A large group of Philips-Sonicare employees from around the world also took part in the symposium. It was definitely an international group.

The two-day, three-evening event was conceived and coordinated by Dr. Berg, with assistance from his team of very talented folks, several of whom just happen to be hygienists. According to Dr. Berg, our understanding of biofilms and the ability to view them as a three-dimensional biological colony will change the way the dental community thinks about diagnosis and prevention. Philips also provided symposium attendees with a CD of Drs. Costerton and Stoodley's work, including video of biofilms.

For many of the attendees, it was the first time they had had an opportunity to hear Dr. Costerton present the exciting news about biofilm structures within plaque. For those of us who attended the conference in London, it was an opportunity to learn more about ongoing biofilm research.

Gingival crevicular-fluid flow increases in periodontitis, so I wonder if plaque biofilm formed in the presence of disease is stronger than plaque biofilm formed prior to disease? Just a thought. To see biofilm images, check out the Montana State University Center for Biofilm Engineering's Web site at default.htm.

Trisha E. O'Hehir, RDH, BS, is a senior consulting editor of RDH. She also is editor of Perio Reports, a newsletter for dental professionals that addresses periodontics. The Web site for Perio Reports is She can be reached by phone at (800) 374-4290 and by e-mail at [email protected].