Plaque Biofilm Flashcards
Intercellular Plaque Matrix
• Matrix that surrounds the bacteria within the plaque biofilm
Intercellular Plaque Matrix
• Composed of
inorganic and organic components that originate from
the bacteria
Intercellular Plaque Matrix
• Major components:
polysaccharides derived from bacterial
metabolism of CHO
Intercellular Plaque Matrix
• Minor components:
salivary glycoproteins
Organic Components of Biofilm
(5)
• Polysaccharides
• Proteins
• Glycoproteins
• Lipid material
• DNA
Inorganic Components of Biofilm
(3)
• Calcium
• Phosphorus
• Trace amounts of sodium, potassium, fluoride
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)
Calculus
(2)
• Hard calcified deposit of plaque that has
become mineralized
• Not easily removed with homecare tools
Non-mineralized
• Dental plaques
Nonemineralized
• Dental plaques
(4)
• Acquired pellicle
• Plaque biofilm
• Materia alba
• Food particles
Mineralized
• Calculus
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
Calculus
• Plaque that becomes mineralized by
calcium and phosphate salts from the saliva
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)
• Calculus is NOT the irritant- — is
plaque
Calculus-continued
removal
• Cannot be removed with a toothbrush, floss, etc. Must be removed
professionally
Calculus-continued
• Can be difficult to remove subgingival calculus without
causing damage
to the root surface
Calculus-continued
• Formation can be accelerated by factors such as (2)
smoking and mouth
breathing
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
Subgingival Calculus
• Located
• (2) are best for detecting
• Derives minerals from
• Color
• Can be tenacious and
• Approximately –% mineralized
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)
• 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:
hydroxyapatite, whitlockite, octacalcium
phosphate, brushite (mixture of calcium and phosphate)
• Mineral sources:
• Supragingival: (1)
• Subgingival: (2)
saliva
gingival crevicular fluid (GCF) and inflammatory
exudate
Attachment to Teeth
(2)
• Surface irregularities on enamel and cementum
• Areas of demineralization
Phases of Dental
Plaque Accumulation
(3)
- Formation of pellicle on
tooth surface - Initial adhesion/attachment of
bacteria - 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
