|
Introduction
Water from dental unit water lines (DUWL) usually contains higher levels of bacteria than municipal water supplies, yet no widespread health problems have been associated with this water. Concern over DUWL contamination has been fueled by an increase in awareness of infection control issues, media reports of contaminated water from dental units, and case reports associating illness with dental water contamination.
Water from dental handpieces, sonic and ultrasonic scalers, and air water syringes continues to be the target of a program to reduce pathogens delivered to the patient during treatment. Dental unit water contains approximately the same types of bacteria found in drinking water, but in a higher concentration. Municipal water is normally maintained with below 500 colony forming units of heterotrophic bacteria per milliliter of water (CFU/mL). Several studies show water from dental handpieces and air-water syringes contaminated at levels exceeding 100,000 CFU/mLs.xiv The ADA has recommended a goal of 200 CFU/mL.
The microorganisms in DUWL are bacteria, protozoa, and fungi. These microorganisms are found in the water as well as attached to the inside walls of the waterline (biofilm). Microbes enter the tubing from incoming water and a very small proportion from dental patients during treatment. These microbes adhere to the walls of the tubing and begin to multiply. The microbes produce a slime layer and more microbes from the water attach to the slime. The flow of the water can dislodge the microbes from the slime layer and release them into the flowing water. The tubing is constantly replenished with more microbes, stagnation of the water facilitates growth of the slime layer, and the small diameter of the tubing results in a large surface-area-to-volume ratio.xv
Water heating systems in dental units are designed to heat the water to human body temperature. This may increase the numbers of microorganisms adapted to growth in human hosts and encourage bacterial growth in the waterlines.xvi Water heating systems should not be used. Waterlines should be flushed after each patient to remove material that may have been retracted during the procedure. Flushing will also dislodge some of the biofilm.
Sterile coolant and irrigating solutions should be used for surgical dental procedures involving bone and incision of mucosa. Water with less than 200 CFU/mL of heterotrophic mesophillic bacteria is acceptable for non-surgical procedures including those involving the sulcus or initial access into dental pulp. xvii
The US Food and Drug Administration (as specified in Section 510(k) of the Federal Food, Drug, and Cosmetic Act) classify dental water treatment and delivery systems as medical devices. They are subject to pre-market standards and must have a 510(k) clearance. Any chemical germicides used must be EPA registered and produce water that must:
Separate water reservoir systems in cooperation with chemical treatment are safe and effective.xvii Technologies for waterline treatment include: independent reservoirs, chemical treatment (either continuous or intermittent), filtration, sterile water delivery systems, and combined approaches. A universal treatment protocol has not been published because dental units and water systems vary. Practitioners should consult their dental unit manufacturer for safe, acceptable methods of providing treatment water with fewer than 200 CFU/mL of heterotrophic mesophillic bacteria.
Dental professionals should:
Water unfit to drink (or swim in) is unfit for therapeutic use in dentistry. ADA's 200 CFU/mL goal is achievable now. Prudence dictates reasonable action to protect dental professionals and dental patients.xviii
Continue on to
|
