ETIOLOGY Flashcards
What is dental plaque?
The structurally and functionally organized, species‐rich microbial biofilm that forms on teeth
What is the main etiologic agent for pdontal disease and dental caries?
dental plaque
What are the characteristics of materia alba?
*White cheeselike accumulation
* A soft accumulation of salivary proteins, bacteria, desquamated epithelial cells, and food debris
*No organized structure
* Easily displaced with a water spray
What are the characteristics of dental plaque?
*Resilient clear to yellow grayish substance
* Primarily composed of bacteria in a matrix of salivary glycoproteins and bacterial products
*Considered to be a biofilm
* Impossible to remove by rinsing or spraying
What are the characteristics of calculus?
*Mineralized dental plaque forms the hard deposit
*Generally covered by a layer of unmineralized dental plaque
What is the composition of dental plaque?
Water
Microorganisms
Intracellular Matrix
What are the components of intracellular matrix of plaque?
Organic component
- Polysaccharides
- Proteins
- Glycoproteins
- Lipids
Inorganic component
- Calcium
- Phosphorous
- Other minerals
- Sodium
- Potassium
- Fluoride
Where is dental plaque found?
- Gingival thirds
- Cracks, pits and fissures
- Under overhanging restorations
- Around crowded teeth
What are the different areas of plaque called?
- Supragingival plaque
- Subgingival plaque
- Marginal plaque
What are the features of supragingival plaque?
Related to calculus formation and root caries
What are the features of marginal plaque?
- Direct contact with gingival margin
- Initiation and development of gingivitis
What are the features of supragingival plaque?
Tissue destruction
What are the types of subgingival plaque?
(very important)
*Tooth Attached Plaque
*Unattached Plaque
*Epithelial Associated Plaque (most harmful)
(very important)
If the sulcular epithelium is intact will there be bleeding on probing?
(very important)
No
What is the most harmful type of subgingival plaque?
(very important)
epithelial associated plaque
What are the microbe components of supragingival plaque?
(very important)
- Gram+ cocci and short rods
- Aerobic environment
- Slight diversity
What are the microbe components of subgingival plaque?
(very important)
- Gram- rods and spirochete
- Anaerobic environment
- Great diversity
Why is supragingival less diverse than subgingival plaque?
exposure to the environment
What are the steps of formation of dental plaque?
Step 1:
Formation of the pellicle
Step 2:
Initial colonization of bacteria
Step 3:
Secondary colonization and plaque maturation
What is the pellicle?
A conditioning film
Where does the pellicle form?
Forms upon immersion of a solid surface into the fluid medium of the oral cavity
What does the pellicle do?
Alters the charge and the free energy of the surface which increases efficiency of the bacterial adhesion
How does the pellicle form?
- An organic material layer coated on all surfaces in the oral cavity, including hard and soft tissues.
- Components derived from saliva and crevicular fluid.
What is the intial stage of plaque formation?
- An organic material layer coated on all surfaces in the oral cavity, including hard and soft tissues. (pellicle)
- Gram+ facultative microorganisms are involved
How do microbes bind to the pellicle?
- Reversible adhesion between the microbial cell surface (adhesins) and the conditioning film (receptors)
- Alters the charge and the free energy of the surface which increases efficiency of the bacterial adhesion
What happens after the initial colonization of microbes on the pellicle?
- Primary colonizers - secondary colonizers
- Bacterial mass continue to grow
- Alteration in the oxygen gradient, anaerobic conditions emerge in the deeper layers of the deposits
What are the primary colonizers?
- Streptococcus spp.
- Actinomyces spp
- Hemophilus spp.
- Neisseria spp.
- Veillonella spp.
What are the secondary colonizers?
- Prevotella intermidia.
- Capnocytophaga spp.
- Fusobacterium nucleatum
- Porphyromonas gingivalis
What are the steps of colonization and maturation of microbes in plaque (coaggregation)?
- Secondary colonizers adhere to the bacteria that are already in the plaque mass
- A significant feature may be seen by the naked eye
- Through further colonization and growth of additional species
- Quorum sensing: cell-cell signaling
What is the structure of dental plaque?
- Open fluid-filled channels running through plaque mass
- Distinct microenvironment produced by the matrix.
- Steep chemical gradients (oxygen, pH)
- Quorum sensing results in bacterial resistance
What is corn-cob formation of plaque?
Cocci attach along the gram-negative filamentous organisms
What is the nonspecific plaque hypothesis?
A direct relationship between the total amount of plaque and the amplitude of pathogenic effects
What is the nonspecific plaque hypothesis mean for periodontal disease?
Control of periodontal disease depends on control of plaque accumulation
What is the nonspecific plaque hypothesis mean for standard of care?
oral hygiene measures, non-surgical/surgical debridement
Our current treatment is based on what plaque hypothesis?
nonspecific plaque hypothesis
(remove all plaque)
All plaque is or is not equally pathogenic?
is NOT
Does all gingivitis develop into
destructive periodontitis?
No
_____ specificity in the pattern of disease was demonstrated in some individuals with periodontitis
Site
What is the specific plaque hypothesis?
The pathogenicity depends on the presence of or increase in specific microorganisms
What is the treatment for the specific plaque hypothesis?
Targeted treatment strategies aim to control or eliminate the particular pathogenic organisms
What pathogens in the same microbial complex (red) are highly pathogenic?
P. gingivalis
B. forsythus
T. denticola
(very important)
Pathogens may be present at the absence of obvious _________
disease
What is the ecologic plaque hypothesis?
- Both the total amount of dental plaque and the specific microbial composition of plaque may contribute
- Microbial homeostasis: the state of the dynamic equilibrium
What are the criteria for Periodontopathogens in Kochs Postulates?
- Be routinely isolated from diseased individuals
- Be grown in pure culture in lab
- Produce a similar disease when inoculated into susceptible lab animals
- Be recovered from lesions in a diseases lab animal
What are the criteria for Periodontopathogens in Socransky’s critera?
- Be associated with disease
- Be eliminated or decreased in sites that demonstrate clinical resolution
- Demonstrate an alteration in host cellular or immune response
- Be capable of causing disease in experimental models
- Demonstrate virulence factors
What two bacteria meet all the criteria for Periodontopathogens?
A. Actinomycetemcomitans
P. Gingivalis
(very important)
What is the host response to A. Actinomycetemcomitans?
Increased serum and local antibody levels
What is the association to A. Actinomycetemcomitans?
Increased in localized aggressive periodontitis lesions. Some in chronic periodontitis lesions
What is the worst serotype of A. Actinomycetemcomitans?
serotype B
What are the virulence factors of A. Actinomycetemcomitans?
Host tissue cell adherence and invasion, leukotoxin, protease, collagenase, epitheliotoxin, FIF, bone resorption inducing factors
What is the host response to P. Gingivalis?
Increased systemic and local antibody levels
What are the virulence factors of P. Gingivalis?
Host tissue cell adherence and invasion, trypsin-like enzyme, collagenase, fibrinolysis, phospholipase A, endotoxin, gingipains, factors that affect PMN function
What is the association with P. Gingivalis?
Increased in periodontitis lesions, found associated with the crevicular epithelium
What helsp microbiologic specificity?
Toxins and enzymes
* Bacterial products that promote tissue destruction: lipopolysaccharides(LPS), leukotoxin, gingipains, collagenase, protease
Evading mechanisms
* Proteolytic degradation of host immunity components: gingipains
* Modulate host response: bind serum components on bacterial cell surface
* Invasion of gingival epithelial cells: lipopolysaccharides(LPS)
* The production of an extracellular capsule
Adhesins
* Factors that promote colonization: fimbria, gingipains
What are the bacteria of necrotizing periodontal disease?
Fusobacterium nucleatum
Prevotella intermedia
Treponema spp.
Spirochete
What are the bacteria associated with pregnancy and puberty?
Prevotella intermedia
Capnocytophaga spp
What are the bacteria in abscess?
- Porphyromonas gingivalis
- Fusobacterium nucleatum
- Parvimonas micra
- Prevotella intermedia
- Spirochetes
What are the bacteria characteristics in health?
- Gram +
- Cocci
- Nonmotile
- Facultative anaerobes
- Fermenting
(very important)
What are the bacteria characteristics in disease?
- Gram -
- Rod
- Motile
- Obligate anaerobes
- Proteolytic
(very important)
Are the periodontal pathogens transmissible?
Periodontal pathogens are communicable but not readily transmissible
