<strong>Decontam<strong>in</strong>ation</strong>: Health Technical Memorandum 01-05 – <strong>Decontam<strong>in</strong>ation</strong> <strong>in</strong> <strong>primary</strong> <strong>care</strong> <strong>dental</strong> <strong>practices</strong> (2013 edition)DUWLs6.80 No currently available s<strong>in</strong>gle method or device willcompletely elim<strong>in</strong>ate biocontam<strong>in</strong>ation of DUWLsor exclude the risk of cross-<strong>in</strong>fection. To reducecontam<strong>in</strong>ation risk, a comb<strong>in</strong>ation of methods isapplicable.6.81 With regard to Legionella and other water-bornepathogenic agents, the HCAI Code of Practice(2009) states:“Premises should be regularly reviewed for potentialsources of <strong>in</strong>fection and a programme should beprepared to m<strong>in</strong>imise any risks. Priority should begiven to patient areas although the exact priority willdepend on local circumstances”.6.82 Guidance from L8 advises that at-risk systems,particularly those used with the patient, be dra<strong>in</strong>eddown at least at the end of each work<strong>in</strong>g day.Where manufacturers provide protocols for dailyclean<strong>in</strong>g, these should be applied.6.83 Self-conta<strong>in</strong>ed water bottles (bottled water system)should be removed, flushed with distilled or ROwater and left open to the air for dry<strong>in</strong>g overnight.They should be stored <strong>in</strong>verted.6.84 Where visual contam<strong>in</strong>ation is present, flush<strong>in</strong>gwith a suitable dis<strong>in</strong>fectant followed by thoroughwash<strong>in</strong>g is necessary. The manufacturer’s<strong>in</strong>structions will specify the dis<strong>in</strong>fectant to be usedand may also require the cont<strong>in</strong>uous presence ofantimicrobial agents to prevent the build-up ofbiofilms.NoteThe self-conta<strong>in</strong>ed water supplies used with <strong>dental</strong> <strong>care</strong>systems should be distilled or RO water (see Section3). Certa<strong>in</strong> systems recycle water back to a storagefacility. Where this is done, repurification will benecessary at each cycle.If self-conta<strong>in</strong>ed water bottles are not used, a Type Aair gap should separate the DUWLs from the ma<strong>in</strong>swater supply. Such arrangements should be subject toconsideration of local water quality, particularly wherehard water is used.Note6.85 DUWLs should be flushed for at least two m<strong>in</strong>utesat the beg<strong>in</strong>n<strong>in</strong>g and end of the day and after anysignificant period when they have not been used(for example, after lunch breaks). In addition, theyshould also be flushed for at least 20–30 secondsbetween patients. Whilst these actions have beenshown to have only a small effect on biofilm buildupwith<strong>in</strong> the DUWL system, they do usefullyreduce microbiological counts <strong>in</strong> the water deliverytube dur<strong>in</strong>g the period when patients are likely tobe exposed. Some water-purification systems arecapable of supply<strong>in</strong>g DUWLs and may be able toreduce microbiological risks.Care should be taken to m<strong>in</strong>imise the occurrence ofsplash<strong>in</strong>g and aerosol formation.6.86 Dis<strong>in</strong>fection of DUWLs should be carried outperiodically. In all cases, the manufacturer’s<strong>in</strong>structions should be consulted. Sodiumhypochlorite and isopropanol and a number ofother agents have been shown to be effective <strong>in</strong>the removal of biofilm as well as the reduction ofmicrobacterial contam<strong>in</strong>ation. However, theseagents should only be used where recommendedby manufacturers. If they are used, <strong>care</strong> shouldbe taken to ensure that DUWLs are thoroughlyflushed after dis<strong>in</strong>fection and before be<strong>in</strong>g returnedto cl<strong>in</strong>ical use.Notes(1) There is disagreement with<strong>in</strong> the scientificliterature concern<strong>in</strong>g the effectiveness of waterbasedflush<strong>in</strong>g of DUWLs, particularly <strong>in</strong> respectof biofilm control. For systems mak<strong>in</strong>g use ofpotable water (that is, where the water supply isdrawn from a ma<strong>in</strong>s water system), the nature ofNotesthe build<strong>in</strong>g’s water-supply arrangements may bean important consideration. This is particularlyso where storage tanks are used. Where deliveredwater quality is <strong>in</strong> doubt, <strong>dental</strong> <strong>practices</strong> shouldconsider adopt<strong>in</strong>g cont<strong>in</strong>uous dos<strong>in</strong>g systemsif permitted by the DUWL manufacturer’srecommendations. If dos<strong>in</strong>g is used, it is importantto ensure that the dose rates delivered are with<strong>in</strong>the recommended safe limits for the product used.Dental <strong>practices</strong> that use a potable water option –through air-gap supply or the use of bottles –should consult with their appo<strong>in</strong>ted CompetentPerson <strong>in</strong> respect of local water quality andsuitability.(2) For those us<strong>in</strong>g purified water, such as distilled orRO, possibly with UV treatment, the rate ofbiofilm build-up is likely to be low, provided thatwater l<strong>in</strong>es are regularly dis<strong>in</strong>fected andma<strong>in</strong>ta<strong>in</strong>ed.40
6 General hygiene pr<strong>in</strong>ciples(3) Particular caution should be taken with regardto <strong>dental</strong> handpieces where dos<strong>in</strong>g is applied, as anumber of <strong>in</strong>stances of damage have been reported.6.87 Dental equipment requir<strong>in</strong>g protection aga<strong>in</strong>stbackflow should have anti-retraction valves<strong>in</strong>corporated on all handpieces, ultrasonic scalersand/or water l<strong>in</strong>es (see Section 3). Responsiblepersons should ensure these are fitted whererequired. They must be regularly monitored andma<strong>in</strong>ta<strong>in</strong>ed.6.88 Examples of <strong>dental</strong> equipment requir<strong>in</strong>g backflowprotection are:• <strong>dental</strong> spittoons;• three-<strong>in</strong>-one syr<strong>in</strong>ges;• wet-l<strong>in</strong>e suction apparatus; and• self-fill<strong>in</strong>g automatic radiographic processors(where still used).Adherence to the equipment manufacturer’srecommended clean<strong>in</strong>g procedures, <strong>in</strong>clud<strong>in</strong>g the useof the manufacturer’s recommended chemicals, is arequirement for medical devices such as those listedabove.6.89 Where <strong>in</strong>-l<strong>in</strong>e filters are used, these will requiretreatment us<strong>in</strong>g an appropriate cleans<strong>in</strong>g solutionat <strong>in</strong>tervals recommended by the manufacturer –but always at the end of each session. This stepshould be performed after first flush<strong>in</strong>g theDUWL.6.90 If the DUWL has disposable filters, they should bereplaced daily.See Section 3 for further guidance on DUWLs.6.91 For <strong>dental</strong> surgical procedures, surgical flapsor other access <strong>in</strong>to body cavities <strong>in</strong>volv<strong>in</strong>girrigation, the use of sterile water or sterileisotonic sal<strong>in</strong>e provided from a separate s<strong>in</strong>gleusesource is recommended.41
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