Controlling biofilm

As guidance and regulations increasingly impact on the operation of the dental practice, it seems reasonable to consider what the guidance says about biofilm, its potential for harm and how the problem should be dealt with.

HTM 01-05 deals extensively with dental unit water lines and biofilm and the relevant guidance is summarised below. However, whether the guidelines address the issue sufficiently is open to debate. In section 6.78 the guidelines state: 'Regular monitoring for microbiological contamination is not considered essential unless there are obvious physical signs of contamination such as poor colour or smell.' The scientific community has long recognised that water can accommodate large numbers of bacteria without any noticeable change in colour or smell and these symptoms are not an accurate indication of whether water lines are contamination free.

The guidelines clearly state the acceptable maximum level of microbiological contamination in section 6.79: 'Where monitoring is carried out the microbiological contamination expressed as TVC (total viable count), the number of viable bacteria per millilitre of water [cfu/ml]) should be expected to lie in the range 100 to 200 cfu/ml.' This is similar to the quality that would be expected for mains supplies or bottled water.