Study Finds Bacteria in Dental Unit Waterlines

Photo by CDC/Larry Stauffer, Oregon State Public Health Laboratory.


Photo by CDC/Larry Stauffer, Oregon State Public Health Laboratory.

Your dental unit waterline may be contaminated with bacteria, reports the Tianjin Centers for Disease Control in China. The organization randomly selected 58 dental chair units (DCUs) from 30 hospitals in Tianjin, one of China’s 4 special municipalities. Next, it used a unique sampling connector in place of the handpiece to collect 263 water samples.

The researchers then cultured 30 water samples in the handpiece group and 21 samples in the air/water syringe groups, yielding bacteria colony counts of greater than 500 colony-forming units (CFUs) per milliliter. The highest concentration of bacteria was found in the handpiece group, totaling 1.8 x 106 CFUs/mL.

Potential infectious agents including Bacillus cereus, Kocuria kristinae, and Pseudomonas fluorescens were isolated from the water samples. A retraction measurement device also was used for retraction evaluation, which 30 of the DCUs failed. There was a significant, positive correlation between bacteria concentration in samples and the retracted volume.

The researchers concluded that compliance with the standards for controlling contamination must be improved, adding that routine microbial monitoring and evaluation of retraction are necessary in dental treatment.

The study, “Evaluation of Bacterial Contamination of Dental Unit Waterlines and Use of a Newly Designed Measurement Device to Assess Retraction of a Dental Chair Unit,” was published by the International Dental Journal.

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