THE MICROBIAL PROFILES OF DENTAL UNIT WATERLINES IN A
DENTAL SCHOOL CLINIC
THE MICROBIAL PROFILES OF DENTAL UNIT WATERLINES IN A
DENTAL SCHOOL CLINIC
Juma AlKhabuli 1a* , Roumaissa Belkadi 1b , Mustafa Tattan 1c
RAK College of Dental Sciences, RAK Medical and Health Sciences University, Ras Al Khaimah, UAE
1
BDS, MDS, MFDS RCPS (Glasg), FICD, PhD, Associate Professor, Chairperson, Basic Medical Sciences
Students at RAK College of Dental Sciences, RAK Medical and Health Sciences University, Ras Al Khaimah, UAE
a
b,c
Received: Februry 27, 2016
Revised: April 12, 2016
Accepted: March 07, 2017
Published: March 09, 2017
Academic Editor: Marian Neguț, MD, PhD, Acad (ASM), “Carol Davila” University of Medicine and Pharmacy Bucharest, Bucharest, Romania
Cite this article:
Alkhabuli J, Belkadi R, Tattan M. The microbial profiles of dental unit waterlines in a dental school clinic. Stoma Edu J. 2017;4(2):126-132.
ABSTRACT
DOI: 10.25241/stomaeduj.2017.4(2).art.5
Background: The microbiological quality of water delivered in dental units is of considerable
importance since patients and the dental staff are regularly exposed to aerosol and splatter generated
from dental equipments. Dental-Unit Waterlines (DUWLs) structure favors biofilm formation and
subsequent bacterial colonization. Concerns have recently been raised with regard to potential risk
of infection from contaminated DUWLs especially in immunocompromised patients.
Objectives: The study aimed to evaluate the microbial contamination of DUWLs at RAK College
of Dental Sciences (RAKCODS) and whether it meets the Centre of Disease Control’s (CDC)
recommendations for water used in non-surgical procedures (≤500 CFU/ml of heterotrophic
bacteria).
Materials and Methods: Ninety water samples were collected from the Main Water Source (MWS),
Distilled Water Source (DWS) and 12 random functioning dental units at RAKCODS receiving water
either directly through water pipes or from distilled water bottles attached to the units. Bacterial
enumeration and molecular identification were performed.
Results: The MWS had the lowest bacterial count (499 CFU/ml).The bottled units contained significantly
higher numbers of CFU (2632±1231.783) compared to non-bottled units (1484.75±1395.093),
p<0.02. Ralstonia spp. was the most common bacteria present in the MWS and DWS (in 96% of the
samples). Other bacteria were Sphingomonas paucimobilis 88.8% and Leifsonia spp. 73.5%.
Conclusion: There is a need for regular water monitoring at dental clinics, in addition to regular
maintenance and disinfection programs to ensure quality water delivery that meets the CDC
guidelines for non-surgical water.
Keywords: Maintaining dental unit waterlines, microbial contamination, biofilm formation, non-
surgical water.
1. Introduction
In the dental office, infection control in terms
of self-protection, instrument sterilization and
surface disinfection is given great importance
due to its huge impact on the patient’s health.
The microbiological quality of water running in
the Dental-Unit Water Lines (DUWLs) however is
mostly overlooked.
Contaminated water in DUWLs causes a health
threat to both patients and dental staff who are
regularly exposed to aerosol and splatter. 1 The
patients with the highest risk of infection from
contaminated water are immunocompromised
patients, elderly patients and patients with recent
surgeries and open wounds.
Bacteria responsible for DUWL contamination
can originate from municipal water piped into
the dental chair unit or from patients’ oral cavities
through a process known as back-siphonage. Back-
siphonage is the process of aspiring oral fluids
as a result of the temporary negative pressure
produced when the drill stops rotating while still in
the patient’s mouth 2,3 due to lack of anti-retraction
valves. 4 In certain conducted studies, it has been
observed that about 1mL of oral fluids is retracted
in old as well as some new dental equipments. 3
This process increases the risk of cross infection
as oral fluids are retracted from one patient’s
oral cavity, grown within the DUWL, and spread
through aerosol or splatter to other patients or
healthcare personnel.
Dental unit water systems’ narrow lumens and
small bores, in conjunction with the long periods
of stagnant water favor the formation of biofilms
which adhere to the inner surfaces of the lines
and serve as a haven for pathogens protecting
*Corresponding author:
Juma Alkhabuli BDS, MDentSci, MFDS RCPS