plaque and biofilm Flashcards
sterile when born?
yes, bac colonize after birth and establish normal flora (2 weeks for gut flora and 2 yrs for whole flora)
how to bac maintain themselves in a host? exceptions?
With the exception of microorganisms that are present in feces and in secretory fluids, all bacteria
maintain themselves within their host by adhering to a surface
most bac can survive in the oropharynx only when?
when they adhere to either soft tissues or the hard
surfaces
how can bac in the oropharynx be removed if not adhered
- Swallowing, mastication, or blowing the nose
- Tongue and oral hygiene implementation
- The wash-out effect of the salivary, nasal, and crevicular fluid outflow
- The active motion of the cilia of the nasal and sinus walls
What ability/virulence factor of a bacterium tis crucial for the induction of infectious diseases such as
gingivitis or periodontitis?
The ability of a bacterium to adhere to its host is crucial for the induction of infectious diseases such as
gingivitis or periodontitis. Oral bacteria have a large battery of virulence factors, one of which is the ability to adhere to hard intraoral surfaces and the oral mucosa
the oral cavity can be divided into 6 major ecosystems
which may also be referred to as niches. They are as follows:
- The intraoral and supragingival hard surfaces (teeth, implants, restorations, and prostheses)
- Subgingival regions adjacent to a hard surface, including the gingival sulcus
- The buccal palatal epithelium and the epithelium of the floor of the mouth
- The dorsum of the tongue
- The tonsils
- The saliva
biofilm composition
Biofilms are composed of microbial cells encased within a matrix of extracellular polymeric substances,
such as polysaccharides, proteins, and nucleic acid
interactions within biofilm
Bacteria that grow in multispecies biofilms interact closely with neighboring cells. Sometimes, these
interactions are mutually beneficial, as is the case when one organism removes another’s waste
products and uses them as an energy source.
diversity of biofilm contents
similarities?
Biofilms are diverse in their content: variations in biofilm structure exist within individual biofilms, between different types of biofilms, and between individuals. However, some structural features that
are common to many biofilms have been noted.
oral example of biofilm
plaque
Intercellular Plaque Matrix
composed of?
major components?
minor components?
Matrix that surrounds the bacteria within the plaque biofilm
• Composed of inorganic and organic components that originate from the bacteria, GCF and saliva
• Major components: polysaccharides derived from bacterial metabolism of CHO
• Minor components: salivary glycoproteins
fluid channels within plaque
how are nutrients delivered?
evidence of open fluid-filled channels running through the plaque mass.
Nutrients make contact with the attached microcolonies by diffusion from the water channels to the microcolony, rather than from the matrix.
biofilm matrix functions as?
barrier
The intracellular
matrix consists of?
organic and inorganic materials derived from saliva, gingival crevicular fluid, and
bacterial products.
Organic constituents of the matrix include:
polysaccharides, proteins, glycoproteins, lipid material, and
DNA.
salivary components of the biofilm
Glycoproteins from the saliva are important components of the pellicle that initially coat a clean tooth
surface, but they also become incorporated into the developing plaque biofilm.
Polysaccharides
produced by bacteria also contribute to?
Polysaccharides
produced by bacteria also contribute to the organic portion of the matrix. They play a major role in maintaining the integrity of the biofilm.
The inorganic components of plaque are:
The inorganic components of plaque are predominantly calcium and phosphorus, with trace amounts of
other minerals such as sodium, potassium, and fluoride.
The source of inorganic constituents of
supragingival plaque is?
as mineral content increases?
The source of inorganic constituents of
supragingival plaque is primarily saliva. As the mineral content increased, the plaque mass becomes calcified to form CALCULUS.
Calculus is frequently found?
in areas of the dentition adjacent to salivary ducts
lingual of mandibular incisors and buccal of maxillary 1st molars
why would calculus be associated with salivary ducts
reflects the high concentration of minerals available from saliva in those regions.
how does sungingival plaque get inorganic components
GCF, can form subgingival calculus
Subgingival calculus color? why?
Subgingival calculus is typically dark green or dark
brown, which probably reflects the presence of blood products that are associated with subgingival
hemorrhage.
Dental plaque is clinically defined as?
Dental plaque is clinically defined as a structured, resilient, yellow-grayish substance that adheres
tenaciously to the intraoral hard surfaces, including removable and fixed restorations.
why cant plaque be removed with rinsing or sprays?
The tough extracellular matrix makes it impossible to remove plaque by rinsing or with the use of sprays.
how is plaque removed
mechanical forces such as brushing and flossing
Materia alba:
app?
consists of?
lacks?
displaced with?
White, cheese-like accumulation
Consists of: salivary proteins, bacteria, desquamated epithelial cells/disintegrating food debris
Lack organized structure/not complex
Easily displaced with water spray
non mineralized deposits
• Dental plaques
• Acquired pellicle
• Plaque biofilm
• Materia alba
• Food particles
mineralized deposits
calculus
Dental plaque is composed primarily of?
Dental plaque is composed primarily of microorganisms.
what covers calculus
plaque
plaque location classification
- Supragingival plaque is found at or above the gingival margin; when in direct contact with the
gingival margin, it is referred to as marginal plaque. - Subgingival plaque is found below the gingival margin, between the tooth and the gingival
pocket epithelium.
how does calculus play a role in perio dx
Plays a major role in periodontitis because it keeps plaque close to the gingival tissues and makes it difficult to
remove the irritant (plaque)
• Calculus is NOT the irritant- plaque is
how is calculus removed
professional scaling
factors exacerbating calculus formation
smoking and mouth breathing
Supragingival Calculus
• location?
• color?
• mineral source?
• Commonly found?
• Approximate % mineralized?
Supragingival Calculus• Coronal to the gingival margin
• White or yellowish in color
• Derives minerals from the saliva
• Commonly found on the lingual aspect of the lower anteriors and
buccal aspect of maxillary molars (adjacent to salivary gland ducts)
• Approximately 30% mineralized
Subgingival Calculus
• Located?
• best methods for detecting?
• Derives minerals from?
• color? why?
• attatchment?
• Approximate % mineralized
Subgingival Calculus• Located below the crest of marginal gingiva; not clinically visible
• Explorer and radiographs are best for detecting
• Derives minerals from inflammatory exudate
• Dense, dark brown or black due to blood components and/or
bacterial degradation
• Can be tenacious and firmly attached to the tooth
• Approximately 60% mineralized
Mineralization of Calculus
* Mineralization of plaque starts where? moves to?
* main crystalline forms?
* Mineralization starts between day _____ of plaque formation
* Does all plaque undergo mineralization?
* Mineral sources?
- Mineralization of plaque starts extra-cellularly (in the intercellular matrix) but eventually occurs within the bacterial cells
- 4 main crystalline forms: hydroxyapatite, whitlockite, octacalcium phosphate, brushite (mixture of calcium and phosphate)
- Mineralization starts between day 1-14 of plaque formation
- All plaque does not undergo mineralization
- Mineral sources:
- Supragingival: saliva
- Subgingival: gingival crevicular fluid (GCF) and inflammatory
exudate
where does plaque attatch to teeth
• Surface irregularities on enamel and cementum
• Areas of demineralization
common forms of calculus formation
phases of plaque formation
- Formation of the pellicle on the tooth surface
- Initial adhesion/attachment of bacteria
- Colonization/plaque maturation
formation of the acquired pellicle
origin of pellicle?
what surfaces?
cleaning?
cells? primarily made of?
serves as?
time for it t mature?
• Originates from the saliva
• Thin, structureless membrane; coats all surfaces in the oral cavity within 1 minute of being removed
• Acellular in nature; consists primarily of glycoproteins
• Colonization of acquired pellicle serves as a nutrient for bacteria
• Takes approximately 7 days for it to develop into it condensed, mature structure
what part of the pellicle allows bacterial adhesion
consists of more than 180 peptides, proteins, and glycoproteins and other molecules that can function as adhesion sites or receptors for
bacteria.
layers of the acquired pellicle
a thin basal layer that is very difficult to remove, and a thicker, globular layer that is easier to detach. I
enamel permanently covered with pellicle?
dental enamel
is permanently covered with an acquired pellicle from the moment that the teeth erupt.
functions of the pellicle
what forms first? 2hrs? multiply? protective layer? 2 days? circ sys?
Plaque Formation Timeline
Initial Adhesion/Attachment of Bacteria to pellicle
what molecules play a role?
what determines wether or not bacteria will remain associated?
The proteins and carbohydrates that are exposed on the bacterial cell surface become important when the bacteria are in loose contact with the acquired pellicle. The specific interactions between microbial cell surface ‘adhesion’ molecules and receptors in the salivary pellicle determine whether a bacterial cell
will remain associated with the surface.
The initial colonizing bacteria of the pellicle include:
The initial colonizing bacteria include gram positive aerobic and facultative organisms like
streptococcus and actinomyces, however, within the first 4-8 hours, the genus Streptococcus tends to
dominate (>20%) of bacteria present
significance of the primary colonizers?
adhesion? metabolism?
provide new binding sites for adhesion by other oral bacteria. The metabolic activity of the primary colonizers modifies the local microenvironment in ways that can influence the
ability of other bacteria to survive in the dental plaque biofilm. For example, by removing oxygen, the
primary colonizers provide conditions of low oxygen tension that permit the survival and growth of
obligate anaerobes.
phases of bacterial colonization
Phase 1 is transport to the
surface
phase 2 is initial reversible adhesion
phase 3 is strong attachment.
inital colonizer spp? metabolisms?
where does most colonization occur?
Initial colonizers: gram (+) aerobic and facultative organisms (actinomyces, streptococcus) attached to pellicle
• Approximately 47-85% cocci during first 4 hours
• Most abundant colonization occurs on proximal surfaces, fissures and gingival sulcus
Secondary colonizers: spp?
metabolism?
initiators of?
P. intermedia, P. gingivalis, Capnocytophaga species, spirochetes, motile rods, gram (-) anaerobic organisms
• These colonizers are the etiologic initiators of caries and periodontitis
MUST ADHERE TO BAC ALREADY IN PLAQUE
how does the bac population change?
The transition from early supragingival dental plaque to mature plaque growing below the gingival margin involves?
involves a shift in the microbial population from primarily gram-positive organisms to high numbers of gram-negative bacteria.
supragingival plaque flora
Gram positive cocci and short rods predominate the tooth surface when supragingival, whereas gram-negative rods, filaments, and spirochetes predominate in the outer surface of the mature plaque mass.
why does subgingival plaque have a dif flora?
primarily because of the local availability of blood products and low redox potential, which characterizes the anaerobic environment.
The composition of the subgingival plaque depends on: what different morphologies are observed becuase of this?
the pocket depth; the apical part is more dominated by spirochetes, cocci, and rods, whereas the coronal part, more filaments are observed.
type of bac?
day1 bac colonization?
gram+ cocci
Day 2-4 bac colonization
Day 2-4: filamentous forms grow on cocci; intercellular matrix forms and connects colonies
what forms increase? what forms begin to appear?
Day 4-7 bac colonization
Day 4-7: filamentous forms increase; rods and fusobacteria appear
what bac morphologies appear? gram? what is visable?
Day 7-14 bac colonization
vibrios and spirochetes appear; gram (-) species increase; clinical inflammation visible
when can ginigivitis become present?
days 14-24
Plaque growth will start at?
areas that are protected from shear forces such as the gingival margin, the
interdental space, and along grooves, cracks, pits and fissures.
plaque maturation (14-24 days)
what can be seen?
plaque composed of?
biofilm structure?
• Day 14-24: gingivitis clinically evident
• Plaque is composed of densely packed vibrios, spirochetes and filamentous bacteria
• Biofilm is well-established; channels established to distribute nutrients, remove wastes, allow free-flowing bacteria to form new colonies
polysaccharides?
Dental Plaque Metabolism
* what is produced when energy sources are introduced?
- When energy sources are introduced (sucrose) microorganisms produce: Acid, intracellular polysaccharides (reserve energy source), Extracellular polysaccharides (glucans [dextrans] and fructans [levans])
- DEXTRANS/ glucans : viscous, sticky substances that anchor bacteria to pellicle and stabilize plaque mass
- LEVANS/ fructans: energy source
plaque composition by mass %
Plaque organisms adapt to?
adverse conditions including varying pH, temperature, ionic strength, absence of nutrients, competing organisms, and inflammatory/immune response
matured plaque resistant to?
mechanical removal
how does plaque cause demineralization?
Anaerobic glycolysis results in pH dropping from 7.0 to below 4.5, resulting in tooth demineralization
how is gingivitis initiated
As bacteria search for nutrients, they migrate sub gingivally
Host defends itself via inflammatory response; gingivitis is initiated
removal? nutrients? undisturbed? interaction?
Factors Affecting
Plaque Accumulation
- Mechanical removal (forces from mastication,toothbrushing, tongue movement, etc.)
- Availability of nutrients
- Undisturbed environment
- Interaction between bacteria and host immune response
is plaque formation rate variable among pts?
yes
Food Debris
• clearance?
• Beverages/sticky foods time?
• plaque a derivative of debris?
• Food debris is rapidly liquefied by bacterial enzymes and cleared from the mouth by salivary flow/muscles of mastication
• Beverages are cleared within 15 minutes; sticky foods, more than 1 hour
• DENTAL PLAQUE IS NOT A DERIVATIVE OF
FOOD DEBRIS
