Podcast
Questions and Answers
What is the term for a change in bacterial community composition due to external, nonmicrobial factors?
What is the term for a change in bacterial community composition due to external, nonmicrobial factors?
Which bacteria are predominantly found in health, according to the specifics of periodontal diseases?
Which bacteria are predominantly found in health, according to the specifics of periodontal diseases?
As the condition progresses from health to periodontitis, what shifts occur in the composition of microbial species?
As the condition progresses from health to periodontitis, what shifts occur in the composition of microbial species?
Which bacterium is generally accepted as the primary etiologic agent in localized aggressive periodontitis?
Which bacterium is generally accepted as the primary etiologic agent in localized aggressive periodontitis?
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In chronic periodontitis, which bacterial species is most often detected at high levels?
In chronic periodontitis, which bacterial species is most often detected at high levels?
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What technique is used for the specific labeling of bacteria in mixed populations?
What technique is used for the specific labeling of bacteria in mixed populations?
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What is the first step in the accumulation of a dental plaque biofilm?
What is the first step in the accumulation of a dental plaque biofilm?
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What does the specific plaque hypothesis suggest?
What does the specific plaque hypothesis suggest?
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According to the ecologic plaque hypothesis, what factors contribute to the transition from health to disease?
According to the ecologic plaque hypothesis, what factors contribute to the transition from health to disease?
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Which of the following is NOT a factor that affects supragingival dental plaque formation?
Which of the following is NOT a factor that affects supragingival dental plaque formation?
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During the first 24 hours after plaque formation begins on a clean tooth surface, what is observed?
During the first 24 hours after plaque formation begins on a clean tooth surface, what is observed?
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Which hypothesis is supported by evidence correlating age and plaque quantity with periodontitis?
Which hypothesis is supported by evidence correlating age and plaque quantity with periodontitis?
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What stage of dental plaque development occurs after the initial attachment of bacteria?
What stage of dental plaque development occurs after the initial attachment of bacteria?
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What type of microorganisms are the first to colonize the oral cavity of newborn infants?
What type of microorganisms are the first to colonize the oral cavity of newborn infants?
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Which components are predominantly found in the inorganic matrix of dental plaque?
Which components are predominantly found in the inorganic matrix of dental plaque?
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Where is supragingival plaque primarily located?
Where is supragingival plaque primarily located?
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Which types of microorganisms dominate the plaque associated with the root cementum?
Which types of microorganisms dominate the plaque associated with the root cementum?
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What is the main composition of the intercellular matrix in biofilms?
What is the main composition of the intercellular matrix in biofilms?
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What type of bacteria are typically found in the apical border of tooth-associated plaque?
What type of bacteria are typically found in the apical border of tooth-associated plaque?
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Which of the following statements is true about marginal plaque?
Which of the following statements is true about marginal plaque?
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What type of microorganisms are most prominent in plaque associated with gingivitis?
What type of microorganisms are most prominent in plaque associated with gingivitis?
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Study Notes
Biofilm and Periodontal Microbiology
- The human fetus is sterile initially but acquires vaginal and fecal microorganisms after birth.
- Within two weeks, a nearly mature microbiota is established in the newborn gut.
- Streptococcus salivarius and Streptococcus mitis are the first and most dominant oral microbes to colonize newborn infants.
- Streptococcus sanguinis, Lactobacillus spp., and Streptococcus oralis colonize teeth after eruption.
Oral Cavity from a Microbe's Perspective
- Epithelial cells shed twice daily via desquamation, a natural cleansing mechanism.
- Brushing of areas like the tongue and under dentures may be beneficial as desquamated cells might not get flushed away.
- Most organisms in the oropharynx need to adhere to tissues/surfaces to survive.
- Removal occurs via swallowing, mastication, nasal blowing, tongue/oral hygiene tools, and the wash-out effect of salivary, nasal, and crevicular fluid outflow.
- Cilia in nasal/sinus walls contribute to removal as well.
Bacteria and their Biofilm Mode of Living
- Biofilms consist of microbial cells encased in a matrix of extracellular polymeric substances (EPS) containing polysaccharides, proteins, and nucleic acids.
- The intercellular matrix has organic and inorganic components like saliva, crevicular fluid, and bacterial products.
- Organic components include polysaccharides, proteins, glycoproteins, lipid material, and DNA.
- Inorganic components include calcium, phosphorus, sodium, potassium, and fluoride.
Bacteria and their Biofilm Mode of Living (Continued)
- Materia Alba: A white, cheese-like accumulation of salivary proteins, some bacteria, desquamated epithelial cells, and occasionally food debris. It lacks a complex organized structure and is easily removed by water spray.
- Dental Plaque: Resilient, clear to yellowish-gray biofilm primarily composed of bacteria in a matrix of salivary glycoproteins and extracellular polysaccharides. It's impossible to remove by rinsing or spraying.
- Calculus: A hard deposit formed through mineralization of dental plaque. Typically covered by a layer of unmineralized dental plaque.
- Supragingival Plaque: Located on or above the gingival margin. Marginal plaque is a specific type when in direct contact.
- Subgingival Plaque: Found below the gingival margin, between the tooth and gingival pocket epithelium.
Bacteria and their Biofilm Mode of Living (Continued)
- Tooth-associated cervical plaque, similar to that in gingivitis, is primarily composed of filamentous microorganisms alongside cocci and rods.
- The apical region of the plaque mass has a layer of host leukocytes separating it from the junctional epithelium.
- This region shows an increased concentration of gram-negative rods compared to elsewhere in the plaque.
- Specific visualization of individual bacteria in mixed populations is possible using techniques like fluorescence in situ hybridization (FISH) or specific antibodies (immunofluorescence).
Bacteria and their Biofilm Mode of Living (Continued)
- The accumulation of dental plaque biofilm occurs in three stages:
- Formation of the pellicle.
- Initial attachment/adhesion of bacteria.
- Colonization/plaque maturation.
Microbiologic Specificity of Periodontal Diseases
- Nonspecific Plaque Hypothesis: This theory suggests a correlation between increasing age, plaque amount, and periodontitis prevalence, thus implying a general relationship.
- Specific Plaque Hypothesis: The pathogenicity of dental plaque depends on the presence of specific microorganisms, and plaque harbouring specific pathogens can cause periodontal disease by producing substances that cause host tissue damage.
Microbiologic Specificity of Periodontal Diseases (Continued)
- Ecological Plaque Hypothesis: Total plaque amount and specific microbial composition are both critical for the transition from health to disease.
- Keystone Pathogen Hypothesis: Certain low-abundance microbial pathogens can orchestrate inflammatory disease, transforming a healthy microbiota into a dysbiotic (unbalanced) one.
The Transition From Health to Disease
- Allogenic Succession (external factors): Change in bacterial community composition due to external factors, such as smoking.
- Autogenic Succession (internal factors): Changes in bacterial community composition resulting from microbial activities and interactions (interbacterial and viral-bacterial).
- Microbial shifts (health to gingivitis to periodontitis) include:
- Gram-positive to gram-negative.
- Cocci to rods/spirochetes.
- Non-motile to motile organisms.
- Facultative anaerobes to obligate anaerobes.
- Fermenting to proteolytic species.
The Transition From Health to Disease (Continued)
- Gingivitis: Predominant gram-positive species (Streptococcus, Actinomyces, etc.) are typically found.
- Chronic Periodontitis: P. gingivalis, T. forsythia, and P. intermedia are commonly found at high levels.
- Localized Aggressive Periodontitis: A. actinomycetemcomitans is a major etiological agent in most cases.
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Description
Test your knowledge on bacterial communities related to periodontal diseases. This quiz covers changes in bacterial composition, key species involved, and the progression from health to periodontitis. Dive into the details of microbial shifts and identify primary etiologic agents in various stages of periodontal conditions.
