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.
The guidelines then go on to indicate a range of measures that can be used to reduce contamination and include the emptying and storage of water bottles at the end of each working day, the use of disinfectants 'periodically' as a prevention measure (although no definition of this is provided) and the flushing of water lines 'for two minutes at the beginning and end of the working day and after breaks. They should also be flushed for 20-30 seconds between patients.' Despite this recommendation the guidance acknowledges that flushing has little effect on biofilm build-up.
In all, the HTM01-05 guidance gives some useful pointers but lacks substantive content on effective decontamination measures.
Evidence base
For many years the problem of biofilm in DUWLs has been studied and data collected that clearly demonstrates the presence of biofilm reduces water quality, making it unlikely to meet the minimum standards required by HTM01-05.
In a study by Walker et al 2000, 95 per cent of samples taken from DUWLs had contamination levels above the current standard for EU drinking water.
For more than two years now, Dentisan has been studying biofilms in DUWLs and the associated water quality in these systems. Laboratory and field evidence has been collected and has clearly shown the challenge of managing DUWLs within the health department guidelines. Studies into the quality of input water have shown that only 20 per cent of samples taken of input water had TVC values below the guideline limit of 200cfu/ml. The presence of biofilm in a DUWL system will add bacteria to the TVC of the input water, so to have any chance of compliance, the input water TVC must be well below the 200 cfu/ml limit.
Solution
The development of Bioclear as a solution to the problem of biofilm was a direct response to the research findings. The challenge was to develop a material that met all the needs of the dental practice in terms of ease of use, reliability and safety and yet was effective in controlling and preventing biofilm and at the same time not harmful to the dental equipment itself.
Bioclear was developed by Dentisan in association with the University of Nottingham school of biosciences and has proven efficacy against the bacteria that make up biofilm, inhibiting re-growth of the film and enabling a system to maintain water quality of < 200="" cfu/ml,="" in="" line="" with="" htm="" 01-05="" section="" 6.79,="" subject="" to="" input="" water="">
Practical development work was undertaken at Nottingham University to demonstrate the effectiveness of Bioclear in biofilm removal. Biofilm was grown in a flow cell using bacteria obtained from a dental unit water line sample and allowed to develop for 10 weeks. The images show that the Pseudomonas aeruginosa biofilm was effectively removed by the product flowing through the cell.
Bioclear is a pH neutral, odourless, non-tainting, ready-to-use solution that requires no mixing. Supplied in one-dose bottles (one bottle is one week's treatment per chair), Bioclear is simply poured into the chair's water bottle, drawn through so that it fills the water lines and left for a minimum of 12 hours. Once the treatment is complete the lines should be flushed through with fresh water until the water runs clear.
How clean is your water?
To combat the problem of biofilm in your practice requires you first to establish the current quality of both input and output water. Although there are differing way to carry out this procedure to simplify the process, Dentisan in association with Henry Schein Minerva are providing a free water quality test. This simple test uses the 3M™ Clean-Trace™ Solution, takes a matter of minutes and is carried out by Henry Schein Minerva's field sales consultants in your practice.