Microbial Quantification and Disinfection Efficacy in Dental Unit Water Lines of a University Clinic

Introduction

Dental unit waterlines (DUWLs) are subject to microbial colonization, following biofilm formation. Therefore, patients and dental staff are unnecessarily exposed to potential pathogens microorganism, increasing the risk of disease or exposure to resistant microorganisms.

Objective

This study aimed to evaluate the microbiological quality of water in dental units at Universidad Privada Franz Tamayo dental clinic and to assess the effectiveness of a regular flushing protocol using 0.12% chlorhexidine gluconate.

Methods

Water samples were collected from the triple syringes of twenty randomly selected dental units after 1 minute of flushing (n=20). Then, 50 µL of the suspensions were seeded in Brain Heart Infusion agar and incubated for 48 h for quantification of colonies. Gram staining was performed for microbial identification. Afterwards, DUWLs were flushed twice per week for six weeks using 0.12% chlorhexidine gluconate and distilled water; subsequently, new samples were collected and seeded in culture medium under the same conditions.

Results

The initial microbial load on DUWLs reached up to 1,640 CFU/mL, with a predominance of Gram-negative bacilli. After the intervention, the mean microbial count decreased to 200 CFU/mL.

Conclusions

The water quality in a high proportion of the university's dental units did not meet standard safety guidelines. Regular disinfection protocols and continuous monitoring systems are necessary to guarantee a safe clinical environment.