Biofilm Control Strategies in Dental Health - Antibiofilm Agents: From Diagnosis to Treatment and Prevention - page 288

against the action of antimicrobial agents, facilitating the establishment of a mature
biofilm. The fact that water is not constantly running and could be stagnant for long
periods of time further increases the odds of a biofilm growing in the DUWS.
The initial colonizers, mostly environmental Gram-negative heterotrophic bac-
teria, are in general not pathogenic organisms and they are not considered a public
health threat. The real problem resides in the fact that important pathogens can
attach to this nonpathogenic biofilm and colonize it, creating a focus of infection
due to the resilience of biofilms. Known human bacterial pathogens recovered from
DUWS include Pseudomonas species, particularly P. aeruginosa, Legionella spe-
cies, particularly L. pneumophila , and nontuberculosis mycobacterial species
(Coleman et al. 2009 ; O'Donnell et al. 2011 ). Moreover, DUWS output water can
also be a major source of bacterial endotoxins released from the cell walls of Gram-
negative bacteria, which can create serious health problems in certain groups of
patients (e.g., asthmatic patients) and stimulate the release of pro-inflammatory
cytokines in gingival tissue during oral surgery.
Nonchemical methods to control bacterial growth in DUWS, such as flushing or
adding filters to the tubing, can be useful to reduce the bacterial content on the
output water but have no effect on the bacterial community growing in the biofilm.
If a pathogen has colonized the pipe system of a DUWS, these methods do not have
any effect in controlling its presence, and the DUWS should be treated with specific
chemicals that also target bacteria growing in biofilms.
4 Biofilm Control Strategies in Oral Health
In the following sections we present a brief overview of different strategies for
controlling biofilms important to oral health in a broad sense. This discussion will
not just consider methods that completely remove the biofilm but rather, in the case
of the oral biofilm, methods that control the biofilm to restore homeostasis, which
should be the ultimate goal of all these treatments. The breath of approaches is
summarized in Table 1 . We divided the different approaches into three main
categories: physical, chemical, and biological control of oral biofilms. However,
we have not included other strategies that may restore biofilm homeostasis but do
not use a direct targeting of the biofilm, such as changing diet habits to a low-sugar
intake, which may be the best prevention of caries but does not specifically target
the oral biofilm to prevent disease. In some cases the distinction between physical,
chemical, or biological treatments is difficult to delimit. For instance, tooth
brushing represents a physical control of the oral biofilm but is almost always
done in the presence of some antimicrobial agent contained in the toothpaste. In
those cases where delimiting the nature of the approach is blurry, we discuss their
properties together.