Microbiology in Periodontology (1) Flashcards
What is periodontitis?
Periodontitis is characterized by microbially‐associated, host‐mediated inflammation, which is modified by the several risk factors resulting in loss of periodontal attachment.
What are examples of host immune response cells which cause inflammation?
MMPs
IL-1
IL-6
lead to loss of periodontal tissue attachment
Is the oral cavity an open growth system?
YES
Why is the oral cavity classed as an open growth system?
as it communicates with the pharynx (oropharynx),
In the oral cavity there is a dynamic equilibrium which exists, but between what 2 things?
Dynamic equilibrium exists between the adhesion forces of microorganisms and a variety of removal forces
What are examples of removal forces in the oral cavity? What do the removal forces originate from?
o swallowing, mastication
o tongue and oral hygiene methods
o washout effect of saliva, nasal and GCF flow
o active motion of cilliae (nasal and sinus walls)
When can most organisms survive in the oropharynx?
Most organisms can survive in the oropharynx only when they adhere to either the soft tissues(short term) or the hard surfaces (Teeth, dentures and implants),
where biofilm is formed.
How many ecosystems are in the oral cavity?
5
What are the 5 major ecosystems in the oral cavity? / niches
- Intraoral, supragingival, hard surfaces (teeth, implants, restorations and prostheses)
- Periodontal pocket (with its crevicular fluid, the root cementum or implant surface and the pocket epithelium)
- Buccal epithelium, palatal epithelium and epithelium of floor of mouth
- Dorsum of the tongue
- Tonsils
Why are teeth and implants unique from a microbiological point of view? (2)
- Provide hard, non-shedding surface that allows for the development of extensive structured bacterial deposit
- Form a unique ectodermal interruption
What forms a seal between the external environment and the internal part of the body?
epithelium and connective tissue
What is dental plaque defined as clinically?
resilient, yellow-greyish substance that adheres tenaciously to the intraoral hard surfaces; including removable and fixed restorations.
What is plaque primarily composed of?
bacteria in matrix of salivary glycoproteins and extracellular polysaccharides
glycoproteins make glucans
How many bacteria does 1gm of dental plaque contain?
10 ^11
What must dental plaque be differentiated form in the oral cavity?
Dental plaque must be differentiated from other tooth deposits, like materia alba and calculus.
What is materia Alba?
Materia Alba refers to soft accumulations of bacteria and tissue cells that lack the organized structure of dental plaque.
washed off with water
NOT PLAQUE
What is calculus?
Calculus is hard deposits that form by mineralization of dental plaque and is generally covered by a layer of un-mineralised plaque.
dentist must remove
NOT PLAQUE
What is shown here?
Dental Alba
What is shown here?
calculus
What is another name for dental calculus?
tartar
What is the process of mineralisation of dental plaque?
saliva has a lot of calcium, the calcium and phosphorus gets deposited onto the soft dental plaque which hardens (mineralised)
It can grow layer by layer
What does this image show?
plaque
and teeth stained with the disclosing agent to show plaque
What is the appearance of materia Alba on teeth?
white cheeselike accumulation
What is the appearance of dental plaque?
resilient clear yellow-grayish substance
What is the appearance of calculus?
hard deposit that forms by mineralisation of dental plaque
generally covered by a layer of un-mineralised plaque
What is dental plaque composed of?
primarily composed of bacteria in a matrix of salivary glycoproteins and extracellular polysaccharides
What is materia Alba composed of?
soft accumulation of salivary proteins, some bacteria, may desquamated epithelial cells and occasional disintegrating food debris
What has a more complex structure materia Alba or dental plaque?
dental plaque, more organised
What are the 3 locations of dental plaque?
- Supra-gingival plaque on single tooth – 10^9 bacterial cells
- Gingival Crevice- 10^3 bacterial cells
- Deep periodontal pocket- 108 bacterial cells
What are examples of non bacterial microorganisms?
Mycoplasma species, yeasts, Protozoa and Viruses.
Where would you find supragingival plaque?
at or above the gingival margin
where would you find marginal plaque?
When it is in direct contact with gingival margin
Where would you find subgingival plaque?
Hard to see
Tooth associated
Tissue associated
What bacteria are predominant in supragingival plaque?
Gram+ve Cocci & short rods
What microorganisms are dominant in marginal plaque?
At this location gram +ve filamentous microorganisms dominate but cocci (streptococci) also occur
What microorganisms are dominant in sub-gingival plaque?
Gm-ve Anaerobes and Spirochetes
predominate
Why does the composition of subgingival plaque differ?
Differs in composition from supra- gingival plaque because of local availability of blood products and low oxygen tension.
What is shown in these images?
subgingival anaerobic gram-negative bacteria
What are the 3 zones in the subgingival plaque?
- tooth attached plaque
- unattached plaque
- epithelial associated plaque
What is the path of the epithelial associated plaque?
migrates onto the connective tissue (gingiva)
It can even migrate to the bone
What happens when bacteria reaches the connective tissue and bone?
bone loss
systemic diseases
What is the gingival crevice bathed in?
Gingival crevicular fluid
What does the gingival crevicular fluid contain?
contains many nutrients that feed the microbial communities in the subgingival area
Where does supragingival plaque receive nutrients?
saliva composition
Does the host inflammatory cells and mediators influence the establishment and growth of the bacteria in the subgingival or supragingival plaque?
subgingival
What disease does the location/site of plaque influence?
diseases of the periodontium
What periodontal disease is associated with the marginal plaque?
development of gingivitis
What periodontal disease is associated with supragingival plaque an dissociated sub-gingival plaque?
Calculus formation and root caries.
What periodontal disease is associated with tissue associated subgingival plaque?
tissue destruction that leads to different forms of periodontitis.
What is the lower plaque layer like?
dense in which microbes are bound together in polysaccharide matrix with other organic and inorganic materials.
What is the top layer of plaque like? (layer on top of lower layer)
loose layer can be seen which is exposed on oral environment
(i.e. teeth and saliva)
What is a biofilm?
Biofilm is a highly organized structure.
Consists of micro-colonies of bacterial cells randomly distributed in a shaped matrix or glycocalyx.
What are the 2 layers that can be the outer layer of plaque?
The fluid layer bordering the biofilm has a stationary sub-layer and a fluid layer in motion.
i.e. can be attached to the biofilm (associated with periodontal disease) or the layer is not attached to the bacteria (planktonic bacteria)
How do the inner layers receive nutrients?
molecular diffusion
What does dental plaque have running across the surface?
open fluid filled channels running across the plaque mass.
Act as primitive “circulating system” - every bacteria has a chance to survive in the dental plaque
What is the role of a polysaccharide?
sticky substance which hold bacteria together
What are examples of organic substances in the intercellular matrix of a biofilm?
- Polysacchrides, Proteins, Glycoprotein & Lipid.
- Albumin derived from GCF.
- Lipid material consists of debris from the membranes of disrupted bacterial & Host cells and possibly Food debris.
- Glycoprotein from saliva important component of pellicle.
- Polysacchrides produced by bacteria of which
- Dextran is most predominant form & play
major role in maintaining integrity of Biofilm.
What is the most predominant polysaccharide produced by bacteria?
dextrin
What are examples of inorganic substances in the intercellular matrix of a biofilm?
- Predominantly Ca and P
- Trace minerals Na, K and F
- As mineral content increases plaque calcifies to
Calculus. - F content of plaque is basically derived from external sources such as fluoridated toothpaste,
mouth rinses, water etc.
What is the source of inorganic constituent of supra-gingival plaque?
saliva
What is the inorganic portion of subgingival fluid derived from?
crevicular fluid
