Controlling biofilm contamination

Key Points

In brief

• All dental units' water lines are contaminated with a biofilm.

• Biofilm contamination is a health hazard to dental personnel and patients.

• There is no easy solution to the contamination problem.

• New technology was tested and found to effectively remove the biofilm and to significantly decrease microbial contamination.

Abstract

Objective To investigate the effect of electro-chemically activated water on biofilm contamination in dental unit water lines.

Design Thirteen dental units fitted with independent water systems and used for 12 years with distilled water were divided into two groups, A and B. At the start, 1 week later, and again 4 weeks later, the bacterial counts in water from all units were determined. Also specimens of tubing were taken from the units at the beginning and at the end of the study for SEM investigation. In Group A distilled water was replaced with electrochemically activated water (a Russian invention), and used continuously for the duration of the study. In group B, distilled water was used as before, until confirmed to be contaminated. For ethical reasons group B was treated, 1 week into the study, with conventional disinfectants.

Setting The project was carried out in a clinic of a department of periodontology of a faculty of dentistry during 1998.

Results Both groups showed a marked reduction in bacterial counts. Under SEM Group A showed a total elimination of the biofilm and Group B a partial removal.

Conclusions Distilled water was ineffective in controlling bacterial counts and biofilm. Electrochemically activated water was effective for this purpose.

Main

Electro-chemically activated water in dental unit water linesJ. T. Marais, V. S. Brözel Br Dent J 1999; 187: 154–158

Comment

Water delivered from dental handpieces and syringe outlets is known to be highly contaminated with microorganisms. The implications of potential pathogens being iatrogenically transmitted to patients undergoing dental treatment are serious. It would appear that the use of municipal water directly connected to dental units could now be considered a sub-standard level of care.

Thirteen dental units in the faculty of dentistry, University of Pretoria, which had been using distilled water for 12 years, were divided into two groups. Two solutions were passed through the units and the degree of contamination with microorganisms compared. Group A used electrochemically activated water (ECA) and group B distilled water which served as the control.

Electro-chemically activated water is a product based on a Russian invention, which has been developed for use in dental unit water lines. ECA is considered harmless to human tissue, yet highly microbicidal. The raw product is tap water and saline. The solution is fed into a special unit, which activates the water using an electric current. Two kinds of ECA solution are produced anolyte and catholyte. Anolyte solution is thought to have the antimicrobial effect and catholyte a detergent or cleaning effect. After 48 hours the ECA solutions return to pure water.

At the start of the study water samples were taken from the 3-way syringes from all 13 units which produced counts of 3 × 10⁴to 2 × 10⁵ colony forming units per millimeter (CFU/ml), additionally pieces of tubing were examined. After 1 week group A (anolyte) gave a reading of 1 CFU/ml and group B 3 × 10⁴ to 2.5 × 10⁵ CFU/ml. The ethical problem arising from these readings led to the control group being altered. The lines, in the control units, were purged daily with both 0.5% sodium hypochlorite and double distilled deionised water.

The units were monitored for 5 weeks at the end of which group A gave counts of 1 CFU/ml, group B gave < 1 CFU/ml. SEM studies of the tubing showed at the beginning well-developed biofilm on all surfaces; at the end of the study group A showed clean tubing with no biofilm. Group B still showed biofilm but in a cracked or desquamated form.

It was concluded that the use of distilled water in independent water systems offers no protection against bacterial contamination. Electrochemically activated water effectively reduces bacterial counts and removes biofilm in dental water lines.