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Page updated 9 October 2006
Saliva ejectors (high speed, low volume aspirators) are prone to back flow during use and the contents could potentially be expelled into the patient's mouth. Oral and waterline bacteria, blood borne viruses, buccal cells, saliva, and blood have all been recovered from suction lines.
Back flow can happen under the following circumstances:
Fortunately, to date there are no documented cases of infection that have been directly linked to back flow from saliva ejectors. However, members of the dental team should be made aware of the small but potential risk of cross infection associated with saliva ejectors if they not handled correctly.
Compressed air is used to operate dental chairs, airturbine handpieces, ultrasonic scalers and other equipment in the dental surgery. Oil lubricated compressors which are the commonest type used in dental practices are prone to colonisation with fungi and pathogenic bacteria such as E. coli (normally found in the human gut and natural waters). Unless precautions are taken a small quantity of the lubricating oil, water and bacteria escapes through the oil filters and into the airlines and ultimately into the patient's mouth and the surgery environment. Oil contamination of the compressed air compromises the performance of airturbines reducing their longevity and interferes with resin bonding of composite restorations. Dental air needs to be clean and dry. The dryer system should be capable of producing air with a dew point not less than minus 20 o C. You can minimise the risk of microbial contamination, by installing a bacterial filter in addition to a dryer and dust filter. Regularly check the dryness of the dental air supplied to the bacterial filter, as microorganisms can penetrate a bacterial filter if the material becomes wet. You will need to test the quality of the air each year in accordance with manufacturer's instructions. Further information on the requirements and standards for dental air quality are described in HTM 2022 available at www.dh.gov.uk
Compressors are covered under The Pressure Systems Safety Regulations 2000 (PSSR ) (see section 3). Before a compressor can be used a "competent person" must draw up a written scheme for periodic examination of the compressor, which outlines the frequency and the nature of the examination. Records must be kept to show that examinations have been carried out and that the examination scheme is reviewed regularly as the equipment ages and is kept up to date. This requirement is separate from servicing and performance testing.