February 21, 2006
Referring Doctors > Information Letters
Biofilms in Root Canals
We are happy to bring you another edition of our endodontic update report. In mid- January, we both attended an interesting all-day presentation given by Dr. Gary Carr of Newport, CA. It was quite enlightening and thought provoking. Dr. Carr limits his endodontic practice to retreatment cases. He is considered by many to be the father of the use of the microscope in endodontics. He has a research foundation that has two one million dollar scanning electron microscopes. One of his primary foci of research is biofilm formation on the root canal wall.
Biofilm is a community of microorganisms attached to a solid surface. Biofilm can contain bacteria, fungi, yeast, protozoa and others. These microorganisms are usually encased in an extracellular polysaccharide that they themselves synthesize. Research has shown that the apical isthmus between the root canals of multi-canal teeth has been found to harbor biofilm.
Today the isthmus is ultrasonically prepped and included as part of the root-end filling when apicoectomies are performed. An example is dental plaque implicated in tooth decay. Biofilm forms when microorganisms adhere to wet surfaces and excrete a slimy, glue-like substance that can stick to all kinds of materials. Their development is most rapid in flowing systems where adequate nutrients are available. Do not be confused between biofilm and the smear layer. The smear layer contains inorganic and organic substances, such as fragments of odontoblasts and necrotic debris. It too, can protect microorganisms within the dentinal tubules, but is a different entity.
Depending on the surrounding environmental conditions, biofilm microorganisms carry out a variety of detrimental or beneficial reactions (from a human perspective). Some reactors designed to promote biofilm growth are very effective for treating environmental wastes such as sewage, industrial waste streams, or contaminated ground water.
Biofilms are responsible for diseases such as otitis media, the most common acute ear infection in children in the United States. Other diseases where biofilms play a role are: bacterial endocarditis(infection of the inner surface of the heart and its valves), cystic fibrosis (a chronic disorder resulting in increased susceptibility to lung infections), and Legionnaire's disease(an acute respiratory infection resulting from the aspiration of clumps of Legionnellabiofilms detached from air and water heating/cooling and distribution systems). Biofilms may be the cause of a wide variety of "nosocomial" (hospital-acquired) infections. Sources of biofilm-related infections can include the surfaces of catheters, medical implants, wound dressings, etc.
Biofilms readily colonize many household surfaces, including toilets, sinks, countertops and cutting boards in the kitchen and bathrooms. Poor disinfection practices and ineffective cleaning products may increase the incidence of illness associated with pathogenic organisms associated with normal household activities. Biofilms are responsible for billions of dollars in lost industrial productivity and both product and capital equipment damage each year. For example, biofilms are notorious for causing pipe plugging, corrosion and water contamination. As dentists we know this to be true with regard to our dental unit water lines.
Biofilms are highly resistant to antibiotics. Therefore, very high and/or long-term doses are often necessary to eliminate biofilm-related infections. Since biofilms can cause a roadblock to managing periapical infections, it appears that its elimination may become the future focus of research in endodontics. We will continue to monitor the progress in this field and keep you informed. Biofilms are not found in vital pulp cases. It takes time for them to form. Perhaps some day it may be possible to remove biofilm from the root canals of infected cases. Today it is unpredictable.
We would like to extend the very best to you and your family in 2006. It's never too late to wish you a happy and healthy New Year!
1. George S. Kishen A, Long P: The Role of Environmental Changes in Monospecies Biofilm Formation on Root Canal by Enterocuccus faecalis, J.O.E., December 2003 (Vol. 31, Issue 12, P.867-872)
2. Leonardo MR, Rossi MA, Silva LAB, Ito IY, Bonifacio KC: EM Evaluation of Bacterial Biofilm and Microorganisms on the Apical External Root of Human Teeth, J.O.E., December 2002 (Vol. 28, Issue 12, P.815-818)
3. Distel JW, Hatton JF, Gillespie M J:Biofilm Formation in Mediated Root Canals,
J.O.E., October 2002 (Vol. 28, Issue 10, P.689-693)
4. Jin Y, Samaranayake LP, Samaranayake Y, Yip HK, Biofilm formation of Candida albicans is variably affected by saliva and dietary sugars, Archives of Oral Biology, October 2004 (Vol.49, Issue 10, P.789-798)
5. Shu M, Wong L, Miller JH, Sissons CH, Development of multi-species consortia of oral bacteria as an enamel and root caries model system, Archives of Oral Biology, January 2000 (Vol. 45, Issue 1, Pages 27-40)
6. Lewandowski Z, Beyenal H, Stookey D, Reproducility of biofilm processes and the meaning of steady state in biofilm reactors. Water Sci Technol, January 2004 (Vol. 49, Issue 11-12, P. 359-64)
7. Rice SA, Koh KS, Queck SY, Labbate M, Lam KW, Kjelleberg S, Biofilm formation and sloughing in Serratia marcescens are controlled by quorum sensing and nutrient cues. J Bacteriol, May 2005 (Vol. 187, Issue 10, P. 3477-85)