Biofilm Control Strategies in Dental Health - Antibiofilm Agents: From Diagnosis to Treatment and Prevention - page 286

pathogenicity as well. Under low sugar concentrations, acidification is rare and
short-lived but if high sugar concentrations persist the acidogenicity of the envi-
ronment increases, selecting for aciduric strains. S. mutans and Streptococcus
gordonii , a non-cariogenic streptococci, are found in inverse proportion in the
oral biofilm (Loesche et al. 1975 ). S. gordonii can antagonize the colonization of
S. mutans by inactivating competence stimulating peptide (CSP) and thus
maintaining a healthy biofilm. Under prolonged acidogenic conditions, mutans
streptococci, lactobacilli, as well as aciduric strains of non-mutans streptococci,
Actinomyces , bifidobacteria, and yeast become dominant and lead to the establish-
ment of a cariogenic biofilm that can cause disease (Takahashi and Nyvad 2011 ).
The other most common oral disease, periodontitis, is responsible for half of all
tooth loss in adults and is a widespread and serious health condition that occurs in
moderate form in 39 % of American adults and in severe form in 9 % of adults, with
prevalence of 70 % in adults older than 65 (Eke et al. 2012 ). Periodontal disease is a
polymicrobial bacterial biofilm-mediated pathology that leads to a progressive loss
of the bone which, if left untreated, results in loosening and eventual tooth loss
(Albandar et al. 1999 ; Oliver et al. 1998 ). L¨e and collaborators demonstrated the
role that accumulation of dental plaque has as the etiological agent of gingivitis, the
first stage in developing periodontitis (Lang et al. 1973 ). Thus, controlling the
growth of dental plaque is a key element in maintaining dental health (Listgarten
1988 ).
Periodontitis is triggered mainly by the presence of a complex microbial biofilm
that colonizes the sulcular space between the tooth surface and the gingival margin.
This biofilm undergoes a change in composition from health to the most severe
forms of periodontitis. As briefly described above, during the succession of colo-
nization of the teeth, the early colonizers are predominantly Gram-positive and later
shift to a more Gram-negative community. Socransky, Haffajee, and colleagues
defined the organisms within the subgingival microbiota, placing them in five
“complexes.” This concept emphasized that microorganisms create their own
habitat, interact with each other, and are implicated in disease severity (Socransky
et al. 1998 ; Socransky and Haffajee 2005 ; Haffajee et al. 2008 ) (Fig. 2 ). The
organisms in the plaque reflected the environmental conditions. The most virulent
combinations were strict anaerobes, and the less virulent microorganisms thrived in
a relatively low-oxygen (microaerophilic) environment. In a detailed analysis using
a checkerboard DNA-DNA hybridization approach of more than 13,000
subgingival samples from nearly 200 adults, Socransky and colleagues demon-
strated that certain bacterial complexes were associated with either health or disease
(Socransky et al. 1998 ). The presence of certain complexes such as the “red
complex” ( Porphyromonas gingivalis , Tannerella forsythia , and Treponema
denticola ) were associated more commonly with clinical indicators of periodontal
diseases and were detected rarely in the absence of bacteria from other complexes.
Finally, though it is not a disease, halitosis or bad breath is a common medical
and social problem caused in most cases by the resident biofilm in the dorsal surface
of the tongue (Zalewska et al. 2012 ). These bacteria produce volatile sulfur
compounds (VSC) that are the cause of halitosis.