1. Dental plaque – biofilm
Medical oral microbiology I – ZLLM0421p
Week 12 Ondřej Zahradníček
Based upon the slideshow of assoc. prof. Vladana Woznicová

2. Oral cavity as a specific environment (partially revision)
Oral cavity is very specific environment, given by its composition
Mucosal surfaces in oral cavity are moistened by saliva, that enable mechanic washing of bacteria, keeping of certain pH, and also non-specific humoural immunity, but also specific immunity (they contain antibodies, mostly class IgA)
Another important part of the invariable environment is sulcar liquid, that is formed in sulcus gingivalis
Oral cavity communicates with outer environment and is influenced by food that is ingested

3. Particular surfaces in oral cavity
Oral microflora is influenced by individual surfaces:
Buccal mucosa – very little colonisation
Surface of the tongue – rich colonisation, commonly by mircroorganisms that come with food and are present just transitionally
Teeth – ideal surface for bacteria, that form dental plaque
Mucous membrane of sulcus gingivalis – small part on the total surface, but big importance
Artificial teeth and dental implantates use to have quite specific microflora

4. Dental plaque – biofilm
Dental plaque is an adherent microbial layer on the tooth surface = live and dead bacteria + their products + host compounds (from saliva)
It can not be washed, can be removed only mechanically
(tooth brushing)
Composition dependent on its location and age
According to the location, it can be differentiated into supragingival and subgingival.
Sometimes also classified as coronary, fissural, supragingival a subgingival. At this classification supragingival plaque is considered the plaque in gingival region (unlike the coronary and the fissural, that are outside this area) but not exactly in the sulcus gingivalis

5. Relations of bacteria in the plaque

6. Subgingival plaque
Subgingival plaque is classified into adherent and nono-adherent one
Adherent plaque – adherent to the dental root, similar to supragingival plaque = i.e. G+ rods, filaments (actinomycetes), and G+ cocci
Non-adherent plaque – between adherent plaque and gingival surface = G- motile anaerobes

7. Subgingival plaque Adherent part Non-adherent part
Rather Gram-positive
Rather Gram-negative
Rather non-motile
Rather motile
Rather facultative anaerobes
Rather strict anaerobes

8. Distribution of microorganisms
Actinomyces sp. is the most frequent genus in both supra- and subgingival plaque
Supragingival plaque – significantly higher amount of some Actinomyces sp., neisseriae, streptococci, and bacteria of "green" and "purple" complex. Periodontal pathogens can be occasionally found in supragingival plaque.
Subgingival plaque – significantly higher amount of Prevotella sp., Tannerella forsythia and Porphyromonas gingivalis , i.e. the "red" a "orange" complex (bacteria possibly worse with regards of risk of parodontitis)
Supragingival plaque acts as reservoir of infections or re-infections of subgingival space
(Ximénez-Fivye et al., 2000)

9. Development of dental plaque
Less than 24 hours: Streptococci of groups mutans, sanguis, and mitis groups are prevalent in supragingival plaque
Days: G+ rods and filamentous microorganisms (lactobacilli, actinomycetes) accumulate
Week: Columns/microcolonies of coccoid microbes – rods and filamentous microbes get attached on their surface
Three weeks: filamentous microbes are prevalent, „corn-cob“ formation: a central filament (Eubacterium yurii) is encompassed by G+ cocci

11. Confocal laser mikroscopy – two-species biofilm, Kolenbrander et al

12. Source: www.bact.wisc.edu

13. Stained biofilm on a catheter (staphylococci and Candida):
a) – channel, b) – fungoid structure
(Photo: Veronika Holá)

14. Dental plaque development (1)
Development of dental plaque starts by a thin layer – pellicula. In the beginning it takes part on the surface on enamel and is source of some ions (calcium, phosphorus)
Nevertheless, pellicula contains glycoproteins, that function as receptors for adhesion of G+ cocci and rods
Exopolysacharid production – the main part of the intercellular matrix
Bacterial metabolism in plaque – other bacterial species involvement,
Plaque development is accelerated by sucrose

16. Dental plaque development (2)
In bottom layers the plaque is mineralised – calcified– plaque step by step contains more and more, finally even 80 % minerals (formation of dental tartar)
Influenced by bacterial metabolism, pH decreases to < 5.5 as a result of bacterial metabolism – enamel demineralisation
Subgingival calculus (concrement) is formed under influence of mostly G– microorganisms
Calculus is porous – filamentous bacteria on the surface – deposits of microbial compounds, that are toxic for parodontal tissues

17. Dental tartar...

18. Dental plaque on dental plates
Different and fluctuating composition
Area close to the mucous membranes – streptococci mutans and sanguinis groups prevalent, and also Candida sp. found very often
Anaerobes – G+ rods including Actinomyces israelii , but also a G– coccus: Veillonella sp.
Commonly also staphylococci, mostly Staphylococcus aureus

19. Bacteria in sulcus gingivalis
Colonising bacteria play main role in origination and development of parodontal disease, environment is clearly anaerobic, washed by sulcar liquid

20. Microflora of gingival sulcus
It contains mostly anaerobic bacteria. These are: actinomycets, fusobacteria (especially F. nucleatum), Prevotella sp., Porphyromonas gingivalis and other species of porfyromonas, further spirochets as Treponema denticola and more species of Treponema
Among streptococci it is mainly Streptococcus anginosus, S. constellatus subsp. constellatus, Streptococcus constellatus subsp. pharyngis, Streptococcus intermedius
Among other bacteria for instance Aggregatibacter (Actinobacillus) actinomycetemcomitans

21. Relationships of bacterial comunities to parodontitis
V.parvula
A.odontolyticus
S.mutans
S.oralis
S.sanguis
P.intermedia
P.nigrescens
P.micros
F.nuc.nucleatum
F.nuc.vincentii
F.nuc.polymorphum
F.periodontium
P.gingivalisT.forsythiaT.denticola
E.corrodens
C.gingivalis
C.sputigena
C.ochracea
A.actinomyc.
Zdroj: Socransky et al. 1998

22. Animals also have dental plaque
Thanks for attendance
Animals also have dental plaque