WATERLINES
To deliver water of optimal microbiologic quality, dental unit waterlines must be maintained regularly. Colonization of microorganisms within the waterlines may not pose a concern for healthy individuals, but it may place elderly or immune-compromised patients at unnecessary risk. Although infection associated with microbial contamination of waterlines appears to be rare, dental unit waterlines have been shown to harbor a wide variety of microorganisms including bacteria, fungi, and protozoans in numbers sufficient to cause illness. These microorganisms colonize and replicate on the interior surfaces of the waterline tubing forming biofilms. Biofilms can serve as a reservoir, amplifying the numbers of free-floating microorganisms in the water.
The Centers for Disease Control and Prevention (CDC) recommends that dental unit water used in nonsurgical procedures measure ≤500 CFU/ml. This is the standard set for drinking water by the Environmental Protection Agency (EPA). To deliver water of this quality, dental unit waterline systems designed for general dental practice must be regularly maintained, via water treatment and monitoring, performed according to the manufacturer’s instructions.
While they will not eliminate biofilms, there are several methods for improving dental unit water quality. However, practitioners should always consult with the manufacturer of their dental units before initiating any waterline treatment protocol. 1. Follow current OSAP, ADA, and CDC recommendations to flush lines for several minutes each morning. Flush handpieces with air/water for 20 to 30 seconds between patient appointments. Installing sterilized handpieces and sterile or disposable syringe tips after flushing will reduce cross-contamination. 2. Always obtain and follow the dental unit manufacturer’s recommendations for treating dental unit waterlines. Implementing protocols not recommended by the unit manufacturer could cause equipment damage and void warranties. 3. If recommended by the dental unit manufacturer, install and maintain anti- retraction valves to prevent oral fluids from being drawn into dental waterlines. 4. Avoid heating dental unit water. While it was common to heat water to increase patient comfort, warming the water may amplify biofilm formation and select organisms pre-adapted to growth in a human host. 5. Consider using a separate water reservoir system to eliminate the inflow of municipal water into the dental unit. In addition to having better control over the quality of the source water used in patient care, it would eliminate interruptions in dental care when “boil-water” notices are issued by local health authorities. Contact the manufacturer of the dental unit for a compatible system and treatment protocols before undertaking this step. 6. Use sterile solutions for all surgical irrigations. Additionally, ensure that only heat-sterilized/sterile-disposable bulb syringes or sterile water delivery devices are employed to deliver the sterile water. 7. Educate and train oral healthcare workers on effective treatment measures to ensure compliance and minimize risks to equipment and personnel. 8. Monitor scientific and technological developments in this area to identify improved technical approaches as they become available. 9. Cooperate with the oral healthcare industry to develop and validate standard protocols for maintaining and monitoring dental unit waterlines. 10. Because insufficient data currently exist to establish the effectiveness of all available methods as used in the dental office, it is important to ensure that any sterile water system or device marketed to improve dental water quality has been cleared for market by the U.S. Food and Drug Administration (FDA). 11. Staff compliance with whatever water treatment approach is chosen by the dental practice is very important. Staff input as to the choice and maintenance is crucial for any success achieved.
AMALGAM SEPARATION
Amalgam separators remove amalgam particles from the wastewater to reduce the amount of amalgam entering the sewage system. Amalgam separators are devices designed to capture amalgam particles from dental office wastewater through sedimentation, filtration, centrifugation, or a combination of these mechanisms. Some separators may also use ion exchange technology to remove mercury from wastewater. Whenever there is need for plumbing work or other activities that might dislodge amalgam waste adhering to the inside of the pipes, it is recommended that steps be taken to minimize potential health or environmental issues.
Water with dental waste flows through the vacuum line and passes through the amalgam separator where teeth fragments, dental amalgam and mercury are separated and collected. The filtered water continues to flow through while heavy waste and sediment is stored.
The Environmental Protection Agency’s (EPA) final rule on amalgam separators was effective as of July 14, 2017, however the date for compliance is July 14, 2020. While one could argue that research shows that dentistry is responsible for less than 1% of the mercury released into the environment, the ADA is supporting this effort and encouraging dentists to follow best practices for amalgam waste handling and disposal. In 2009, the Association amended its best management practices to include the use of amalgam separators that comply with ANSI/ADA Standard 108 for Amalgam Separators, which takes into consideration the standards developed by the International Organization for Standardization, a worldwide federation of national standards bodies.
American National Standards Institute/American Dental Association (ANSI/ADA) Standard No. 109 defines amalgam waste as including amalgam (scrap), chair-side trap filters containing amalgam vacuum pump filters containing, amalgam, saliva ejectors if used in dental procedures involving amalgam, used amalgam capsules, extracted teeth with amalgam restorations, and waste items that are contaminated with amalgam. Dental best management practices for amalgam waste handling and disposal include use of chair-side traps, use of amalgam separators, regular inspection and cleaning of traps, and use of appropriate commercial waste service to recycle and/or dispose of collected amalgam. Compliance with the EPA final rule on amalgam separators is required.
DO:
- use precapsulated alloys and stock a variety of capsule sizes
- recycle used disposable amalgam capsules
- salvage, store, and recycle non-contact (scrap) amalgam
- salvage (contact) amalgam pieces from restorations after removal and recycle their contents
- use chair-side traps, vacuum pump filters, and amalgam separators to retain amalgam and recycle their contents
- recycle teeth that contain amalgam restorations (Note: Ask your recycler whether extracted teeth with amalgam restorations require disinfection)
- manage amalgam waste through recycling as much as possible
- use line cleaners that minimize dissolution of amalgam
DON’T:
- use bulk mercury
- put used disposable amalgam capsules in biohazard containers
- put non-contact amalgam waste in biohazard containers, infectious waste containers (red bags), or regular garbage
- put contact amalgam waste in biohazard containers, infectious waste containers (red bags), or regular garbage
- rinse devices containing amalgam over drains or sinks
- dispose of extracted teeth that contain amalgam restorations in biohazard containers, infectious waste containers (red bags), sharps containers, or regular garbage
- flush amalgam waste down the drain or toilet
- use bleach or chlorine-containing cleaners to flush wastewater lines
Additional highlights of the rule include:
- Dentists who practice in oral pathology, oral and maxillofacial radiology, oral and maxillofacial surgery, orthodontics, periodontics, and prosthodontics are exempt from the rule.
- Dentists who do not place amalgam and only remove amalgam in unplanned or emergency situations (estimated at less than 5 percent of removals) are also exempt.
- Mobile dental units are exempt.
- Dentists who already have separators are grandfathered for 10 years.