There is little evidence to indicate that bacteria contained within DUWL have been associated directly with the development of infections in patients or dental health care workers. However a number of bacteria identified in biofilm from DUWL are opportunistic bacteria which are known to cause illnesses which have significant morbidity and, indeed, significant mortality. As the CDC guidelines have indicated, failure to deal with this issue is inconsistent with good infection control practices. In addition, the putative link between bacteria associated with refractory periodontitis and DUWL biofilm gives cause for concern. There are a number of products available which, if used as directed, are effective in controlling DUWL biofilm and ensuring the provision of an irrigating solution with bacterial levels which conform to the CDC and ADA guidelines. If a surgical periodontal procedure is undertaken then it is important that handpieces or ultrasonic/sonic scalers are supplied with sterile water delivered through disposable or autoclavable tubing.