Transcript Few4y efewfwfny

Chapter 24
Dental Unit Waterlines
Copyright 2003, Elsevier Science (USA).
All rights reserved. No part of this product may be reproduced or transmitted in any
form or by any means, electronic or mechanical, including input into or storage in any
information system, without permission in writing from the publisher.
PowerPoint® presentation slides may be displayed and may be reproduced in print
form for instructional purposes only, provided a proper copyright notice appears on
the last page of each print-out.
Produced in the United States of America
ISBN 0-7216-9770-4
Introduction
Outbreaks of waterborne disease have occurred in
a broad range of facilities. Although there is no
evidence of a widespread public health problem,
published reports have associated illness with
exposure to water from dental units. The fact that
there are bacteria capable of causing disease in
humans found in dental unit waterlines is reason
for concern.
Copyright 2003, Elsevier Science (USA). All rights reserved.
Introduction- cont’d



In community water, the number of waterborne
bacteria is kept below 500 colony-forming units
(CFU) per milliliter.
The water from air-water syringes and dental
handpieces frequently has bacteria levels that are
hundreds or thousands of times greater than is
permissible in drinking water.
The types of bacteria that are found in dental unit
water are frequently the same types as those
found in community water, but the levels of
bacteria found in the dental units are almost
always higher.
Copyright 2003, Elsevier Science (USA). All rights reserved.
Background




Dental health care workers are exposed to Legionella
bacteria at a much higher rate than the general public.
Dental personnel are exposed to contaminated dental
unit waterlines by inhaling the aerosol generated by
the handpiece and the air-water syringe.
There is at least one suspected fatality of a dentist
from legionellosis.
Case reports have been published of
immunocompromised patients who developed
postoperative infections caused by contaminated
dental water.
Copyright 2003, Elsevier Science (USA). All rights reserved.
Microorganisms in Waterlines




The primary source of microorganisms in dental
waterlines is the public water supply.
It is possible that saliva may be retracted back into the
waterlines during treatment. This process is also called
“suck back.”
Antiretraction valves on dental units and thorough
flushing of the dental lines between patients minimize
the chance of this occurring.
Entering public water source has a colony forming
units (CFU) count of less than 500; once that water
enters the dental waterlines and colonizes within the
biofilm, the CFU count skyrockets.
Copyright 2003, Elsevier Science (USA). All rights reserved.
Communities of Bacteria

There are two “communities” of bacteria in dental
unit waterlines:
• One bacterial community exists in the water
itself and is referred to as planktonic (free
floating).
• The other exists in the biofilm attached to the
walls of the waterlines.
Copyright 2003, Elsevier Science (USA). All rights reserved.
Fig 24-1 Close up of dental tube opening.
Fig. 24-1
Copyright 2003, Elsevier Science (USA). All rights reserved.
Fig. 24-2 A cross-section of a dental unit waterline illustrating the formation
of biofilm on the inside wall of a dental tube.
Fig. 24-2
Copyright 2003, Elsevier Science (USA). All rights reserved.
Fig 24-4 Maze of dental unit lines.
Fig. 24-4
Copyright 2003, Elsevier Science (USA). All rights reserved.
Biofilm




Biofilm exists in all places where moisture and a
suitable solid surface exist.
Biofilm consists of bacterial cells and other
microbes that adhere to surfaces and form a
protective slime layer.
Biofilm can contain many types of bacteria, as well
as fungi, algae, and protozoa.
Viruses, such as the human immunodeficiency
virus (HIV), cannot multiply in the dental unit
waterline.
Copyright 2003, Elsevier Science (USA). All rights reserved.
Fig. 24-3 Magnification of biofilm formation on the walls of the tube.
Fig. 24-3
Copyright 2003, Elsevier Science (USA). All rights reserved.
Fig. 24-5 Bacteria in biofilm dropping into waterlines.
Fig. 24-5
Copyright 2003, Elsevier Science (USA). All rights reserved.
Methods to Reduce Contamination

It is not yet possible to totally eliminate biofilm,
but it can be minimized by:
• Self-contained water reservoirs
• Chemical treatment regimens
• Microfiltration
• Daily draining and drying of lines
Copyright 2003, Elsevier Science (USA). All rights reserved.
Self-Contained Water Reservoirs



These systems supply air pressure to the water bottle
(reservoir).
The air pressure in the bottle forces the water from the
bottle up into the dental unit water lines (DUWL) and out
to the handpiece and air-water syringe.
Self-contained water systems have two advantages:
• The dental personnel can select the quality of water to
be used, such as distilled, tap, or sterile.
• Maintenance of the water system (between the
reservoir bottle and the handpieces and syringes) is
under the control of the dentist and staff.
Copyright 2003, Elsevier Science (USA). All rights reserved.
Fig 24-6 Self-contained dental water unit.
Fig. 24-6
Copyright 2003, Elsevier Science (USA). All rights reserved.
Microfiltration Cartridge



A disposable inline microfiltration cartridge also
can dramatically reduce the bacterial
contamination in the dental unit water.
This device must be inserted as close to the
handpiece or air-water syringe as possible.
It should be replaced at least daily on each line.
The use of filtration cartridges combined with
water reservoirs can ensure improved water
quality.
Copyright 2003, Elsevier Science (USA). All rights reserved.
Fig. 24-8 Disposable microfiltration filter in place near the handpiece at the
end of the waterline.
Fig. 24-8
Copyright 2003, Elsevier Science (USA). All rights reserved.
Chemical Agents

Chemicals can be used to help control biofilm in
two ways:
• Periodic or “shock” treatment with biocidal
levels (levels that will kill microorganisms) of
chemicals.
• Continuous application of chemicals to the
system (at the level to kill the microorganisms
but not harm humans).

Always check with the manufacturer of the dental
equipment to determine which chemical product
and maintenance protocol they recommend.
Copyright 2003, Elsevier Science (USA). All rights reserved.
Water for Surgical Procedures


Dental unit water should not be used as an irrigant
for surgery involving the exposure of bone.
Only use sterile water from special sterile water
delivery systems or hand irrigation using sterile
water in a sterile disposable syringe.
Copyright 2003, Elsevier Science (USA). All rights reserved.
Flushing Waterlines




All dental waterlines and handpieces should be
flushed in the mornings and between patients.
Although this will not remove biofilms from the
lines, it may temporarily reduce the microbial
count in the water.
It will help clean the handpiece waterlines of
materials that may have entered from the
patient’s mouth.
Flushing also brings a fresh supply of chlorinated
water from the main waterlines into the dental
unit.
Copyright 2003, Elsevier Science (USA). All rights reserved.
Minimize Aerosol


Always use the high-volume evacuator when using
the high-speed handpiece, ultrasonic scaler, and
air-water syringe.
The high-volume evacuation may also reduce
exposure of the patient to these waterborne
microorganisms.
Copyright 2003, Elsevier Science (USA). All rights reserved.
Use Protective Barriers



The dental dam greatly reduces direct contact.
The dam also greatly reduces the aerosolizing and
spattering of the patient’s oral microorganisms
onto the dental team.
Protective barriers, including masks, eyewear, and
face shields, also serve as barriers for the dental
team.
Copyright 2003, Elsevier Science (USA). All rights reserved.