Plaque Biofilm Flashcards
what is biofilm
- a layer of living organisms that can attach to a solid object
- composed of microbial cells
- encased within a matrix that acts as a barrier
- diverse
- frequently contain microcolonies of bacterial cells
what are the 6 regions of the mouth
- tonsils
- dorsum of tongue
- buccal palatal and floor of mouth epithelium
- intraoral and supragingival hard surfaces
- saliva
- subgingival regions adjacent to hard surfaces
where is the plaque matrix and what is it composed of
- surrounds the bacteria within the plaque biofilm
- composed of inorganic and organic components that originate from the bacteria
what are the major components of plaque matrix
polysaccharides derived from bacterial metabolism of carbohydrates
what are the minor components of plaque matrix
salivary glycoproteins
what are the organic components of biofilm
- polysaccharides
- proteins
- glycoproteins
- lipid material
- DNA
what are polysaccharides produced by and what is their role
produced by bacteria
- majro role in maintaining the integriy of the biofilm
what do glycoproteins do
important part of the pellicle
- add to the bacteria in the matrix and helps the growth rate continue
what are the inorganic components of biofilm
- calcium
phosphorus - trace amounts of sodium, potassium , fluoride
what is the source of inorganic components of biofilm
supragingival plaque and saliva
describe dental plaque and how is it removed
- nonmineralized
- naturally acquired bacterial biofilm that develops on teeth
- multi species biofilm
-sticky, colorless film which constantly forms over teeth - removed with mechanical forces like brushing and flossing
what are the types of plaque
supra gingival and sub gingival
what does supragingival plaque cause
gingivitis
what does subgingival plaque cause
periodontitis
what is the topography of supragingival plaque
- initial growth along gingival margins and interdental spaces
- later, further extension in the coronal direction
- may also originate from grooves, cracks or pits
what is materia alba and what is it made of
- white cheese like accumulation
- consists of salivary proteins, bacteria, desquamated epithelial cells/ disintegrating food debris
- lacks organized structure/ not complex
how do you get rid of materia alba
water spray
describe calculus
- plaque that becomes mineralized by calcium and phosphate salts from the saliva
- plays a major role in periodontitis because it keeps plaque close to the gingival tissues and makes it hard to remove the irritantswh
what is the irritant
plaque NOT calculus
what is primary source for supragingival calculus
saliva
what is the primary source for sub gingival calculus
GCF
when does calulcus begin to from
1-14 days between plaque accumulation
where is calculus most commonly found and why
- lower anterior region because of salivary gland
- # 3 and #14 buccal surface because of parotid gland
how is calculus removed
professionally
what can calculus formation be accelerated by
smoking and mouth breathing
where does mineraliztion of calculus occur and when
- in the intercellular matrix; eventually occurs within the bacterial cells
- starts between day 1-14 of plaque formation but not all plaque undergoes mineralization
what is calculus made of
- 70-90% inorganic components
- 10-30% organic components
what are the 4 main crystal forms of calculus
- hydroxyapatite 58%
- magnesium whitlockite 21%
- octacalcium phosphate 12%
- brushite 9%
describe supragingival calculus
- coronal to the gingival margin
- white or yellowish in color
- derives minerals from the saliva
- commonly found adjacent to salivary gland ducts
- approximately 30% mineralized
describe 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 firmyl attached to the tooth
- approximately 60% mineralized
describe calculus and attachment to teeth
- surface irregularities on enamel and cementum
-areas of demineralization
what is on cementum
- organic pellicle
- mechanical locking into surface irregularities
- close adaptation to gentle depression or sloping mounts of unaltered cementum
- bacterial penetration into cementum surfaces
what are the types of calculus formation
- spicules
- ledge
- ring
- veneer
what are the phases of dental plaque accumulation
- formation of pellicle on tooth surface
- initial adhesion/ attachment of bacteria
- colonization / plaque maturation
describe the formation of acquired pellicle
- originates from saliva
- thin structureless membrane; coats all surfaces in the oral cavity within 1 minute of being removed
- acellular in nature, consists of glycoproteins
- colonization of acquired pellicle serves as a nutrient for bacteria
- takes 7 days to develop into condensed mature structure
describe initial adhesion/ attachment of bacteria
- bacteria colonization occurs as soon as it is introduced in the mouth
- primary colonizers provide binding sites for other bacteria
what are the 3 phases of colonization
- transport to the surface
- initial reversible adhesion
- strong attachment
describe colonization and plaque maturation
- coadhesions occurs because of bacteria attaching to primary colonizing bacteria
- coadhesion leads to the growth of microcolonies and biofilm
what is the significance of the pellicle and describe each function
- protective: provides barrier against acids, reducing dental caries attack
- lubrication: keeps surface moist, prevents drying
- nidus for bacteria: key role in development of plaque
- aides in the attachment of calculus
what happens each day in stage 2- bacterial colonization
- day 1: gram positive cocci
- day 2-4: filamentous forms grow on cocci; intercellular matrix forms and connects colonies
- days4-7: filamentous forms increase, rods and fusobacteria appear
- days 7-14: vibrios and spirochetes appear, gram negative species increase, clinical inflammation visible
what are the stages of biofilm formation
- stage 1; pellicle formation
- stage 2: bacterial colonization
- stage 3: plaque maturation
what happens in the days of plaque maturation
- 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
what is the plaque formation timeline
- 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 mulitply
- microcolonies are formed; streptococci secrete a protective layer known as slime layer
- within 2 days microcolonies double in mass and from complex groups with metabolic advantages. plaque is visible at this point
- biofilm develops a primitive circulatory system
what are the initial colonizers in plaque and where do they colonize
- gram positive aerobic and facultative organisms
- actinomyces
- streptococcus
- 47-85% cocci during first 4 hours
- most abundant colonization occurs on proximal surfaces, fissures and gingival sulcus
what are the secondary colonizers of plaque
- P intermedia
- P gingivalis
- capnocytophaga
- spirochetes, motile rods
- gram negative anaerobic organisms
- initiators of caries and periodontitis
when energy sources are introduced microorganisms produce:
- acid
- intracellular polysaccharides - reserve energy source
- extracellular polysaccharides- glucans and fructans
what are dextrans
viscous, sticky substance that anchor bacteria to pellicle and stabilize plaque mass
what are levans
energy source
how do plaque organisms adapt to adverse conditions
varying pH, temperature, ionic strength, absence of nutrients, competing organisms, and inflammatroy/ immune response
what are the factors affecting plaque accumulation
- lack of mechanical removal
- availability of nutrients
- undisturbed environment
- interaction between bacteria and host immune response
what makes bacteria in biofilms resistance to antibiotics
- bacteria in microbial communities are different from bacteria growing in suspended liquid environment
- organisms in biofilm are 1000-1500 X more resistant to antibiotics
- biofilm matrix has properties that slow down antibiotic penetration
- slower rate of growth of bacterial species makes them less susceptible to antibiotics
how is food debris cleared
liquefied by bacterial enzymes and cleared from the mouth by salivary flow/ muscles of mastication
how long are beverages and sticky foods cleared
- beverages: within 15 minutes
- sticky foods: more than an hour
is dental plaque a derivative of food debris
no
how long does it take for biofilm to mature
14-24 daysh
as bacteria search for nutrients:
they migrate sub gingivally
how does the host defend itself against plaque
inflammatory response -> gingivitis
