Water is essential to the practice of dentistry. Water is used to irrigate surgical sites, to cool dental devices such as handpieces and ultrasonic scalers, and to irrigate restorative sites for better visibility. Water is used in nearly every modern dental practice.
Standards for safe drinking water quality are established by EPA, the American Public Health Association (APHA), and the American Water Works Association (AWWA). The standards set limits for heterotrophic bacteria of ≤500 CFU/mL of drinking water. Thus, the number of bacteria in water used as a coolant or irrigant for non-surgical dental procedures should be as low as reasonably achievable and, at a maximum, ≤500 CFU/mL, the regulatory standard for safe drinking water established by EPA and APHA/AWWA.
Most new dental units in the United States now have a separate water reservoir. Using a separate water reservoir system enables the use of water other than the local municipal water supply. In addition to having better control over the quality of the source water used in patient care, it eliminates interruptions in oral health care when boil-water notices are issued by local health authorities. However, a separate water reservoir, even when using distilled or sterile water, does not prevent biofilm development in dental unit waterlines.
Since 2003, CDC has recommended that all dental units should use systems to provide output treatment water to meet drinking water standards (i.e., ≤ 500 CFU/ mL of heterotrophic water bacteria) for routine (non-surgical) procedures. CDC further clarified that independent reservoirs—or water-bottle systems—alone are not sufficient. In order to achieve the CDC recommended value of ≤500 CFU/mL of water used in routine (i.e., non-surgical) oral health treatment, other strategies must be employed.
Chemical products remove or inactivate biofilm or prevent its formation. Chemical treatments are either continuously infused into or intermittently added to the dental unit water. It may be necessary to remove biofilm in the dental unit waterlines using a shock treatment before initial use of a chemical treatment product. Beyond initial shocking of the dental unit waterlines, the specific chemical treatment product manufacturer should provide instructions for routine or periodic shocking of the lines.
Two types of treatment systems are available. The first employs treatment cartridges that release an active ingredient that disinfects and filter devices that remove solid particles from water. The treatment cartridge is connected to the dental unit’s existing water bottle pickup tube. Treatment cartridges need to be replaced at regular intervals, according to the product-specific manufacturer’s instructions for use. Filter devices are installed in the waterline between the dental unit waterline and the dental instrument (such as dental handpiece or air/water syringe). The filter does not affect biofilm in waterlines but removes microorganisms as the water exits the waterline, through the filter, to the dental instrument. Filters must be periodically replaced, with the frequency depending on the amount of biofilm in the waterlines and the manufacturer’s instructions. They may or may not remove endotoxin.
The second type of system employs dental unit waterline treatment products and devices that are regulated by either FDA or EPA. Continuous chemical treatment products, systems, and filters designed for dental unit waterline treatment are regulated by FDA. Intermittent chemical treatment products are registered with EPA as cleaners or disinfectants for dental unit waterline treatment.
Consult the dental unit manufacturer to determine the compatible methods, products, and devices to maintain the quality of dental water in specific dental units. For other dental devices, such as ultrasonic scalers with independent water reservoirs, consult the manufacturer of the device that uses water for instructions and recommended products to control biofilm in the waterlines.
Critical elements of a successful dental unit waterline treatment approach include training staff in site-specific dental unit waterline treatment protocols and monitoring compliance. Those responsible for maintenance of independent reservoir bottles must handle the bottles with clean gloves and follow the manufacturer’s instructions for cleaning and aseptically managing the bottles. Use the CDC checklist to assess compliance with the CDC guidelines.
During surgical procedures, CDC recommends the use of only sterile solutions as coolants or irrigants in an appropriate delivery device, such as a sterile bulb syringe, sterile tubing that bypasses dental unit waterlines, or sterile single-use devices.
The CDC definition of oral surgical procedures are those that “involve the incision, excision, or reflection of tissue that exposes the normally sterile areas of the oral cavity. Examples are biopsy, periodontal surgery, apical surgery, implant surgery, and surgical extractions of teeth (removal of erupted or nonerupted tooth requiring elevation of mucoperiosteal flap, removal of bone or section of tooth, and suturing if needed).”
It is important to ensure that any sterile water or coolant system or device marketed to improve dental unit water quality has been cleared for market by FDA.