Pathogeneisis of Periodontal Disease Part 1 Flashcards
(36 cards)
What types of bacteria are seen in the oral cavity hours after birth and on the second day of life?
Facultative and aerobic bacteria
Anaerobic bacteria
How does saliva promote the growth of health-associated microbiota?
Even though the saliva has antimicrobial properties it
- aids in bacterial attchament via selected salivary proteins and glycoproteins that form the acquired enamel pellicle
- supplying nutrients
How do microbes persist in the oral cavity?
Adhering to either the hard or soft tissues to avoid removal forces
What is the major distinction between intra-oral environments colonized by microbes?
Whether the microbial communities are formed on shedding (oral mucosa) or non-shedding surfaces (teeth, restorations, implants, etc)
How do teeth and implants provide a surface for the development of extensive bacterial deposits?
they are non-shedding surfaces that allow bacteria to bind to the acquired enamel pellicle
How fast is the acquired enamel pellicle formed?
1 min
How does periodontitis provide a subgingival ecological niche?
formation of periodontal pockets leads to development of low-oxygen microhabitats that favors anaerobic bacterial colonization
What are the steps of the formation of the dental biofilm?
- formation of the pellicle on the tooth surface
- initial adhesion and attachment of bacteria
- colonization/biofilm maturation
what happens during the initial adhesion and attachment of bacteria in biofilm formation?
first 4-8 hours, streptococcus species dominate (20%) and obligate aerobes primarily colonize the site
- they provide new binding sites
- remove oxygen that permits survival of obligate anaerobes
what happens during colonization and biofilm maturation in biofilm formation?
- coadhesion: primary colonizers provide new attachment receptors
- micro-colonies form
- biofilm develops beneath the gingival margin
- shift from gram positive bacteria to gram negative
why must dental biofilms be mechanically removed?
the tough extracellular layer makes them impossible to remove with just rinsing
what are supragingival biofilms and subgingival bioflms?
- supragingival: at or above the gingival margn; when in direct contact with the gingival margins its called the marginal biofilm
- subgingival: below the gingival margin; between tooth and gingival pocket
what are the structural differences between the supragingival biofilm and subgingival bioflm?
- supragingival: Gram-positive cocci and short rods at the tooth surface, gram-negative rods, filaments, and spirochetes on the outer surface
- subgingival: fastidious strict anaerobes because of the local availability of blood products and a low REDOX protential
How does periodontal pocket depth correlate to subgingival biofilms?
composition depends on the depth
- apical portion is spirochetes, cocci, and rods
- coronal part is more filaments
How does calculus form?
as the mineral content of the biofilm increases (crevicular fluid) the biofilm mass becomes calcified and is covered with a layer of unmineralized dental plaque
where is calculus frequently found?
- dentition adjacent to salivary ducts
What is materia alba?
soft accumulations of bacteria, food matter, and tissue cells that lack the organized structure of dental biofilms and that are easily displaced with a water spray
what is the initial supragingival biofilm formation pattern?
initial growth along the gingival margin and from the interdental spaces (i.e., the areas protected from shear forces) and later, a further extension in the coronal direction
how does the rate of biofilm formation differ in adjacent teeth and different parts of the mouth?
- tooth surfaces facing inflamed gingiva have a more rapid biofilm accumulation than teeth facing healthy gingiva
- occurs faster in the lower jaw
What is the Specific Plaque Hypothesis and how are bacteria categorized?
- importance of the qualitative composition of resident microbiota, recognizing A. actinomycetemcomitans as a pathogen in localized aggressive periodontitis where bacteria are categorized into color-coded complexes:
- Yellow, Purple, Green: Host-compatible species.
- Orange Complex: Pathogenic species that multiply before red complex colonization.
- Red Complex: Contains T. forsythia, P. gingivalis, and T. denticola, which are linked to deeper probing depths and bleeding.
Can you have the presence of pathogens and not have periodontitis?
yes
What is the Ecologic Plaque Hypothesis and its significance in oral disease?
the amount and composition of dental biofilms influence the transition from health to disease where changes in host response due to factors like inflammation, hormonal imbalance, or environmental influences (e.g., smoking, diet) can disrupt microbial balance, leading to dysbiosis and chronic diseases like periodontitis
For an organism to be judged as a periodontal pathogen it must?
- Association Postulate: associated with disease –> increases in the number of organisms at diseased sites
- Elimination/Suppression Postulate: eliminated or decreased in sites that demonstrate the clinical resolution of disease with treatment
- Induce a host response in the form of an alteration in the host cellular or humoral immune response
- Be capable of causing disease in experimental animal models
- Produce demonstrable virulence factors that are responsible for enabling the microorganism to cause the destruction of the periodontal tissues
what happens during the transition from health to disease in the subgingival microbiota?
gram-positive, aerobes or facultative anaerobes shift towards gram-negative, anaerobic species in disease
- Specific periodontal pathogens like Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythi
