Sampling Water from Chemically Cleaned Dental Units with Detachable Power Scalers

Abstract

This study’s purpose was to determine the effect chemical cleaning had on the microbial quality of water emitted from dental unit waterlines (DUWL), 3-way syringes, and power scalers.

Purpose. This study’s purpose was to determine the effect chemical cleaning had on the microbial quality of water emitted from dental unit waterlines (DUWL), 3-way syringes, and power scalers.

Methods. Ten randomly selected dental units with attached self-contained independent water reservoirs filled with deionized water were used. An ultrasonic scaler was paired with each of the ten units. This combination was retained for the duration of the study. Water samples were collected at the beginning of the fall semester and again after two weeks. Analysis indicated unacceptable levels of microorganisms and the need for a shock treatment, which included cleanings on 3 consecutive days. Water samples were collected following the initial shock treatment and for the following 4 weeks. Weekly cleanings were performed as part of routine equipment maintenance. Water specimens from the 3-way syringes and scaler handpieces were spiral plated on R2A agar plates. Incubation was at room temperature for 7 days. Plates were examined and the number of colony-forming units per milliliter (CFU/mL) was determined for each specimen.

Results. The first sampling showed that none of the 3-way syringes and one of the power scalers produced potable water after sitting unused for 6 weeks and receiving only one chemical cleaning. Improvement was noted after the second cleaning with specimens from 8 units having bacterial levels <500 CFU/mL. Three power scalers emitted potable water. Improvements in the bacterial levels of the power scalers were noted following the shock treatment; all of the power scalers emitted potable water.

Conclusions. Practitioners should routinely treat dental units and power scalers with products that will maintain acceptable microbial water quality. Administration of a shock treatment may be necessary prior to beginning a weekly maintenance protocol. Shock treatments are beneficial if units or power scalers have not been used for an extended period of time.