Plaque Biofilm Flashcards by sophie rosen

Intercellular Plaque Matrix

• Matrix that surrounds the bacteria within the plaque biofilm

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Intercellular Plaque Matrix
• Composed of

inorganic and organic components that originate from
the bacteria

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Intercellular Plaque Matrix
• Major components:

polysaccharides derived from bacterial
metabolism of CHO

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Intercellular Plaque Matrix
• Minor components:

salivary glycoproteins

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Organic Components of Biofilm
(5)

• Polysaccharides
• Proteins
• Glycoproteins
• Lipid material
• DNA

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Inorganic Components of Biofilm
(3)

• Calcium
• Phosphorus
• Trace amounts of sodium, potassium, fluoride

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Dental plaque
(4)

• a naturally acquired bacterial biofilm that
develops on teeth
• Multi-species biofilm
• Sticky, colorless film which constantly
forms over teeth
• Removed with mechanical force such as
toothbrushing/flossing)

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Calculus
(2)

• Hard calcified deposit of plaque that has
become mineralized
• Not easily removed with homecare tools

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Non-mineralized

• Dental plaques

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Nonemineralized
• Dental plaques
(4)

• Acquired pellicle
• Plaque biofilm
• Materia alba
• Food particles

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Mineralized

• Calculus

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Materia Alba
(4)

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

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Calculus

• Plaque that becomes mineralized by
calcium and phosphate salts from the saliva

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Calculus
• Plays a major role in periodontitis
because it

keeps plaque close to the
gingival tissues and makes it difficult to
remove the irritant (plaque)

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• Calculus is NOT the irritant- — is

plaque

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Calculus-continued
removal

• Cannot be removed with a toothbrush, floss, etc. Must be removed
professionally

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Calculus-continued
• Can be difficult to remove subgingival calculus without

causing damage
to the root surface

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Calculus-continued
• Formation can be accelerated by factors such as (2)

smoking and mouth
breathing

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Supragingival Calculus
• — to the gingival margin
• — in color
• Derives minerals from the
• Commonly found on the
• Approximately –% mineralized

Coronal
White or yellowish
saliva
lingual aspect of the lower anteriors and
buccal aspect of maxillary molars (adjacent to salivary gland ducts)
30

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Subgingival Calculus
• Located
• (2) are best for detecting
• Derives minerals from
• Color
• Can be tenacious and
• Approximately –% mineralized

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below the crest of marginal gingiva; not clinically visible
Explorer and radiographs
inflammatory exudate
Dense, dark brown or black due to blood components and/or
bacterial degradation
firmly attached to the tooth
60

Mineralization of Calculus
(4)

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• Mineralization of plaque starts extra-cellularly (in the intercellular
matrix) but eventually occurs within the bacterial cells
• 4 main crystalline forms
• Mineralization starts between day 1-14 of plaque formation
• All plaque does not undergo mineralization

• 4 main crystalline forms:

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hydroxyapatite, whitlockite, octacalcium
phosphate, brushite (mixture of calcium and phosphate)

• Mineral sources:
• Supragingival: (1)
• Subgingival: (2)

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saliva
gingival crevicular fluid (GCF) and inflammatory
exudate

Attachment to Teeth
(2)

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• Surface irregularities on enamel and cementum
• Areas of demineralization

Phases of Dental Plaque Accumulation (3)

1. Formation of pellicle on tooth surface 2. Initial adhesion/attachment of bacteria 3. Colonization/plaque maturation

Acquired Pellicle • Originates from the • Thin, structureless membrane; coats all surfaces in the oral cavity within • --- in nature; consists primarily of --- • Colonization of acquired pellicle serves as a • Takes approximately --- for it to develop into its condensed, mature structure

saliva 1 minute of being removed Acellular, glycoproteins nutrient for bacteria 7 days

Significance of Pellicle (4)

Protective Lubrication Nidus for bacteria Aides in the attachment of calculus

Protective

• Provides a barrier against acids, thus reducing dental caries attack

Lubrication

• Keeps surfaces moist, prevents drying

Nidus for bacteria

• Key role in development of plaque

Plaque Formation Timeline (6)

Pellicle forms first on the tooth, providing bacteria a surface to attach to Within 2 hours, bacteria is loosely bound to the pellicle Bacteria continues to spread throughout the mouth and multiply Microcolonies are formed; streptococci secrete a protective layer (also known as the ‘slime layer’) Within 2 days microcolonies double in mass and form complex groups with metabolic advantages (plaque is clinically visible at this point) Biofilm develops a primitive circulatory system

Initial colonizers: (3)

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

skipped Secondary colonizers: (2)

P. intermedia, P. gingivalis, Capnocytophaga species, spirochetes, motile rods, gram (-) anaerobic organisms • These colonizers are the etiologic initiators of caries and periodontitis

Stages of Biofilm Formation (3)

Stage 1- pellicle formation Stage 2- bacterial colonization Stage 3- plaque maturation

Stage 2- bacterial colonization • Day 1: • Day 2-4: • Day 4-7: • Day 7-14:

gram (+) cocci filamentous forms grow on cocci; intercellular matrix forms and connects colonies filamentous forms increase; rods and fusobacteria appear vibrios and spirochetes appear; gram (-) species increase; clinical inflammation visible

Stage 3- plaque maturation • Day 14-24: (3)

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

Dental Plaque Metabolism • When energy sources are introduced (sucrose) microorganisms produce: (5)

• Acid • Intracellular polysaccharides (reserve energy source) • Extracellular polysaccharides (glucans [dextrans] and fructans [levans]) • DEXTRANS: viscous, sticky substances that anchor bacteria to pellicle and stabilize plaque mass • LEVANS: energy source

Plaque (mass)= Dextrans: Levans: Bacteria:

20% 10% 70-80%

Plaque organisms adapt to adverse conditions including (6)

varying pH, temperature, ionic strength, absence of nutrients, competing organisms, and inflammatory/immune response

These conditions affect the prolonged existence of the

biofilm

In response, the bacteria find their ‘ecologic niche’ which allows them to

flourish within their own microcosm

Plaque cannot be removed by

spraying water

As is matures, it becomes resistant to

mechanical removal

Anaerobic glycolysis results in pH dropping from

7.0 to below 4.5, resulting in tooth demineralization

As bacteria search for nutrients, they migrate

sub gingivally

Host defends itself via inflammatory response;

gingivitis is initiated

Factors Affecting Plaque Accumulation (4)

• Mechanical removal (forces from mastication, toothbrushing, tongue movement, etc.) • Availability of nutrients • Undisturbed environment • Interaction between bacteria and host immune response

Do some patients form plaque faster than others?

Yes! Heavy and light plaque formers exist! However, in both cases, it takes days before the plaque is clinically visible. Patients cannot justify poor oral hygiene by being heavy plaque formers.

Food Debris (3)

• 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

Plaque Biofilm Flashcards

(49 cards)