Why Is It There?

What is Biofilm?

Biofilm is the greatest potential source of disease transmission from patient to patient, and patient to dental worker.

Biofilm is a community of micro-organisms, which grow naturally in water. These micro-organisms grow and attach to a solid surface, such as the inside of the small-bore plastic tubing that delivers coolant water to dental handpieces, sonic and ultrasonic scalers and air-water syringes.

A biofilm community can include bacteria, spores, viruses, fungi, yeasts, protozoa and other micro-organisms. Many, including spores, are difficult to kill and may be drug resistant.

A virtual “protective nest” of living organisms – a slime layer known as a glycocalyx – biofilm forms wherever water is flowing or stagnant, such as in water mains, ponds and streams. This bacterial slime becomes a growing microbial reservoir, amplifying free-floating micro-organisms that enter and are transported by water.

The different species of disease-causing pathogens in dental waterline biofilm can number in the hundreds. The levels of bacteria in water from newly installed dental unit waterlines can reach 200,000 CFU/mL of water within five days of installation. The small diameter of dental tubing creates a high surface-to-volume ratio for enhanced biofilm growth.

In the 21st Century, the danger of infectious disease transmission in dentistry is heightened because of

1) the emergence of more dangerous microbes that defy medical treatment and can lead to a fatality

2) a rise in patients who are immuno-compromised due to other conditions, and are therefore much more susceptible to disease with fatal consequences

3) a rise in antibiotic-resistant strains.

– Dr. Robert Hasel, DDS

Dental plaque is a form of biofilm. But the danger comes when biofilm containing pathogens from many different patient sources form on the surface of the small-bore plastic tubing in dental units.

These micro-organisms eventually slough off into the water, forming a highly toxic time bomb for patients most susceptible to disease. Even patients with normal immune systems are at risk.

Before water systems were used to cool high-speed handpieces and the bulb syringe was used to flush dental debris, patients did not share the same dental unit — and thus weren’t exposed to each others’ microbes from the oral cavity. Today, patients (and dental workers) share a “common” system and can be exposed to diseases carried by the person who just left the same dental chair.

If we are going to deliver sterile procedures, it is critical to isolate each patient's pathogens from the next patient.

Common Pathogens in Waterlines

Biofilm in dental unit waterlines may contain hundreds of various bacteria, virus, fungal and protozoan species. Some can be serious:

• HIV/AIDS virus (NTM)
• Pseudomonas species
• Streptococcus
• Staphylococcus
• Non-tuberculous mycobacteria
• Klebsiella pneumoniae
• Tuberculosis (TB)
• Legionella

Although documented cases of disease caused by exposure to dental aerosols are few, both altered nasal flora and serological evidence of exposure to Legionella bacteria have been reported in dental healthcare workers.

These Lead to Serious Disease

• HIV/AIDS
• Hepatitis
• Tuberculosis, respiratory infections
• Bacterial endocarditis
• Legionnaire’s disease

Pseudomonas-related diseases in immune-compromised patients

- Urinary tract infections
- Soft tissue infections
- Bone and joint infections
- Systemic infections
- Dermatitis
- Bacteremia
- Gastrointestinal infections

The Immune-Compromised Patient is at Most Risk

Dental practitioners are increasingly faced with immune-suppressed patients.

Patients at higher risk of infection from contaminated dental water include those suffering from HIV/AIDS, tuberculosis, cystic fibrosis, diabetes, leukemia, lupus, and asthma, the elderly, alcoholics, smokers, patients undergoing immunosuppressive medication (chemotherapy) or radiation therapy, organ transplant recipients and prosthetic joint recipients.

The HIV/AIDS patient is of particular concern, as oral lesions or periodontal disease often develop in early stages, while the HIV patient is very susceptible to microbial disease. Legionella and the Pseudomonas pose the greatest danger — Legionella for respiratory infection and the Pseudomonas that strike when immune systems are weakened.

Cross-contamination of viral and bacterial infections from AIDS patients to subsequent dental patients is a significant risk. Since HIV/AIDS may be undetected, all patients should be treated as immuno-compromised.