CDA Essentials 2019 • Volume 6 • Issue 6

40 | 2019 | Issue 6 S upporting Y our P ractice Infection Prevention and Control at the Dental Office the potential for misleading interpretations of water quality (as measured by CFU/ml). For example, when one line does not meet an acceptable standard for water quality (i.e., the sample measures >500 CFU/ ml of heterotrophic bacteria) but water quality in the four other lines is very good (e.g., the samples measure 10 CFU/ml of heterotrophic bacteria), the aggregate sample would still be within the acceptable range for water quality (<500 CFU/ml). For this reason, I recommend initially testing each line individually. • The Organization for Safety and Asepsis Prevention (OSAP) 3 suggests using an external water testing company. External testing can provide quantitative measurements of microbial contamination and identify the organisms. But two factors could discourage use of external water testing companies. The first is a risk of false readings unless the water samples are handled, transported and maintained exactly as directed by the testing company. The second reason is cost: in-office testing is far less expensive and easier to perform, and results are available sooner. Each office will need to consider the pros and cons of in-office versus external water testing. However, consideration should be given to external water testing at least once a year to provide qualitative and quantitative results. • Once initial test results are known, if the numbers for the source water are high, change the source water and retest. If the numbers for any line(s) are approaching 500 CFU/ml, reshock, retest and continue. • Once the numbers for every line are well below the 500 CFU/ml level, OSAP recommends monthly retesting on an aggregate basis. 3 However, because conditions change constantly in offices, and every office and chair may have different needs, it would be safer to establish a testing routine (perhaps weekly and just prior to shocking) that would ensure disinfection strategies can be tailored to identified needs. • Once routines for maintaining water quality have been established with monthly testing, and if there are no changes to staffing, equipment, source water, office temperatures or patient numbers, testing could be performed quarterly. Documentation is essential. Patterns identified after a year of regular testing can highlight any problem areas that should be regularly monitored. a References 1. Chandler J. Dental Waterlines: Understanding and Controlling Biofilms and Other Contaminants. Vista Research Group, LLC. Available at: hu-friedy.com/sites/default/files/SpecialReport_DentalWaterlines_ FINAL.pdf (Accessed July 2, 2019) 2. Health Canada. Guidance on the Use of Heterotrophic Plate Counts in Canadian Drinking Water Supplies. 2013-01. Available at: canada.ca/en/health-canada/services/publications/healthy-living/guidance- use-heterotrophic-plate-counts-canadian-drinking-water-supplies.html (Accessed July 2, 2019) 3. MillsS,PorteousN,ZawadaJ. DentalUnitWaterQuality:Organization forSafety,AsepsisandPreventionWhitePaperandRecommendations–2018. JournalofDental InfectionControlandSafety. 2018;1(1):1-27. Lines should be flushed at the start of the treatment day and between each patient; each waterline that was used during patient care should be flushed for at least 20 seconds to remove suck back. ➜ † Health Canadadoesnotuseheterotrophicplatecount fordrinkingwaterstandards.Becausethere isnostandard fordentalunitwaterlines inCanada,wedefaulttotheCenters for DiseaseControlandPrevention(CDC)guidelineof500CFU/ml.