2- dental plaque
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Questions and Answers

What is the primary cause of dental caries, gingivitis, periodontitis, and peri-implant infections?

  • Salivary origin
  • Dental Plaque (correct)
  • Extracellular polymeric substance (EPS)
  • Microbial community

    • How is a biofilm defined?

  • A material not dislodged by rinsing
  • A yellow-greyish material closely adhered to tooth surfaces
  • A microbial community adhered to tooth surfaces
  • An assemblage of microbial cells enclosed in primarily extracellular polymeric substance (EPS) matrix (correct)

    • What is the composition of the matrix in which the diverse microbial community of dental plaque is embedded?

  • Primarily extracellular polymeric substance (EPS)
  • Microbial cells
  • Polymers of bacterial and salivary origin (correct)
  • Non-shedding material

    • What percentage of dental plaque (biofilm) is composed of microorganisms?

    <p>15-20% (D)</p> Signup and view all the answers

    What is the inorganic content of the extracellular matrix in dental plaque?

    <p>Calcium and phosphate (A)</p> Signup and view all the answers

    Which organic content is found in the extracellular matrix of dental plaque?

    <p>Protein, carbohydrates, and lipids (C)</p> Signup and view all the answers

    What is the primary composition of dental plaque (biofilm)?

    <p>Extracellular Matrix and Microorganisms (D)</p> Signup and view all the answers

    What is a main cause of intrinsic tooth stains?

    <p>a and b (D)</p> Signup and view all the answers

    What is the composition of Materia Alba deposit?

    <p>Dead Epithelial Cells, Leukocytes, and Microorganisms (C)</p> Signup and view all the answers

    What can easily remove Materia Alba from tooth surfaces?

    <p>Water spray (A)</p> Signup and view all the answers

    What is the primary inorganic component of calculus?

    <p>Calcium phosphate (A)</p> Signup and view all the answers

    Which organic component is found in the organic content of calculus?

    <p>Lipids, salivary proteins and carbohydrate (C)</p> Signup and view all the answers

    What is the percentage of organic content in calculus?

    <p>20% (B)</p> Signup and view all the answers

    Which form of calculus is primarily found in the mandibular anterior area?

    <p>Brucite (B)</p> Signup and view all the answers

    Where is the mature calculus primarily composed of hydroxyapatite found?

    <p>Supragingival areas in bulk (C)</p> Signup and view all the answers

    In which area is the later calculus primarily composed of octacalcium phosphate found?

    <p>Posterior areas and sublingual (A)</p> Signup and view all the answers

    Which form of calculus is characteristic of the posterior areas and sublingual region?

    <p>Magnesium whitlockite (C)</p> Signup and view all the answers

    What percentage of mature calculus is composed of hydroxyapatite?

    <p>58% (C)</p> Signup and view all the answers

    How soon is the formation of a conditioning film detected after cleaning/initial exposure of the oral environment?

    <p>Within 1 minute (D)</p> Signup and view all the answers

    When does the conditioning film reach equilibrium after its formation?

    <p>By 2 hours (D)</p> Signup and view all the answers

    What type of interaction characterizes reversible adhesion in bacterial adhesion?

    <p>Weak interaction between charges on microbial cell surface and acquired pellicle (A)</p> Signup and view all the answers

    What defines irreversible adhesion in bacterial adhesion?

    <p>Strong interaction between specific molecules on microbial cell surface and complementary molecules in acquired pellicle (D)</p> Signup and view all the answers

    How do secondary and late colonizers adhere in co-adhesion during bacterial adhesion?

    <p>Via cell-surface adhesions to receptors on already attached bacteria (A)</p> Signup and view all the answers

    What is the result of Stage 3 in the formation of biofilm matrix?

    <p>Multiplication Growth of Attached Bacterial Cells (Co-Aggregation) and Synthesis of new outer membrane components (D)</p> Signup and view all the answers

    What is the role of new outer membrane components in Stage 3 of biofilm formation?

    <p>They contribute to the synthesis of the biofilm matrix (B)</p> Signup and view all the answers

    What facilitates the development of synergistic and antagonistic interactions in Stage 4 of biofilm formation?

    <p>Close proximity of cells with one another (D)</p> Signup and view all the answers

    What do the gradients in nutrients and fermentation products within the plaque result in during biofilm formation?

    <p>A mosaic of microenvironments (C)</p> Signup and view all the answers

    What is the outcome of the metabolism of microorganisms during biofilm formation?

    <p>Establishment of a mature biofilm with a stable composition (B)</p> Signup and view all the answers

    How do some species of bacteria respond if conditions deteriorate?

    <p>By upregulating enzymes to cleave their adhesins and detach (C)</p> Signup and view all the answers

    What is the specific species mentioned in the text that responds by detaching and colonizing elsewhere?

    <p>A. actinomyctemcomitans (A)</p> Signup and view all the answers

    What is the adaptive response of bacteria to changes in their environment as described in the text?

    <p>Upregulating enzymes to cleave adhesins and detach (C)</p> Signup and view all the answers

    What enzyme system is responsible for neutralizing toxic Superoxides and Hydrogen Peroxides in bacteria?

    <p>Superoxide dismutase (A)</p> Signup and view all the answers

    Why can oxygen be harmful to some bacteria?

    <p>Due to the formation of Superoxides and Hydrogen Peroxides (D)</p> Signup and view all the answers

    What must bacteria that do not produce Superoxide dismutase, Catalase, and Peroxidase enzymes do?

    <p>Live in anaerobic conditions (C)</p> Signup and view all the answers

    Which type of bacteria can use anaerobic respiration to survive without O2?

    <p>Obligate anaerobes (D)</p> Signup and view all the answers

    Which type of bacteria requires O2 to live?

    <p>Obligate aerobes (B)</p> Signup and view all the answers

    Which type of bacteria can use both aerobic and anaerobic respiration to survive?

    <p>Facultative anaerobes (B)</p> Signup and view all the answers

    Which type of bacteria has an outer lipopolysaccharide membrane?

    <p>Bacteria with a thin peptidoglycan cell wall layer (A)</p> Signup and view all the answers

    What is the distinguishing feature of Gram-positive bacteria's cell wall?

    <p>Stains blue-purple (A)</p> Signup and view all the answers

    What makes the cell wall of Gram-negative bacteria less acidic?

    <p>Absence of teichoic acid (D)</p> Signup and view all the answers

    Which type of microorganisms are associated with the transition to oral disease, as mentioned in the text?

    <p>Gram-negative rods and filaments (C)</p> Signup and view all the answers

    What is the role of commensal microbiota in promoting oral health, as per the information provided?

    <p>Resistance to colonization by allowing few opportunities for integration by exogenous pathogens (D)</p> Signup and view all the answers

    Which bacterial species are positively associated with oral health, according to the text?

    <p>Gram-positive cocci and rods (A)</p> Signup and view all the answers

    Which complexes become more dominant as disease progresses in the initial colonization of tooth surface?

    <p>Orange and red complexes (C)</p> Signup and view all the answers

    Which complex species are difficult to find without the presence of orange complex species?

    <p>Purple complex species (B)</p> Signup and view all the answers

    What is the significance of the absence of a beneficial organism in a biofilm, according to the text?

    <p>It is as important as the presence of a pathogen in disease (C)</p> Signup and view all the answers

    What is the role of quorum sensing in biofilm formation?

    <p>Encouraging the growth of beneficial bacterial species to the biofilm (C)</p> Signup and view all the answers

    What are the potential roles of quorum sensing in bacterial community structure?

    <p>Modulating the expression of genes for antibiotic resistance (C)</p> Signup and view all the answers

    What allows obligatory anaerobic bacteria to survive in an aerobic environment within a biofilm?

    <p>Co-aggregation to oxygen-consuming species (A)</p> Signup and view all the answers

    What is a mechanism of metabolic interactions among bacteria in a biofilm?

    <p>Nutritional co-operation (A)</p> Signup and view all the answers

    What is the consequence of reaching the critical concentration threshold in quorum sensing?

    <p>Triggering change in gene expression (D)</p> Signup and view all the answers

    What characterizes the physiological state of particular cells of the same microbial species in a biofilm?

    <p>Exhibiting different physiological states in close proximity (B)</p> Signup and view all the answers

    What is the primary consequence of antagonistic interactions among bacteria in a biofilm?

    <p>Production of inhibitory compounds to inhibit growth of neighboring cells (D)</p> Signup and view all the answers

    What is the primary consequence of quorum sensing in biofilm formation?

    <p>All of the above (D)</p> Signup and view all the answers

    What allows obligatory anaerobic bacteria to survive in an aerobic environment within a biofilm?

    <p>Co-aggregation to oxygen-consuming species (A)</p> Signup and view all the answers

    According to the Non-specific Plaque Hypothesis, what was believed to be the result of periodontal disease in the mid-1900s?

    <p>Accumulation of plaque over time in conjunction with a diminished host response and increased host susceptibility with age (A)</p> Signup and view all the answers

    What allowed for the elaboration of noxious products by the entire plaque flora, as per the Non-specific Plaque Hypothesis?

    <p>Diminished host response and increased host susceptibility with age (C)</p> Signup and view all the answers

    According to the Specific Plaque Hypothesis, what results in specific periodontal disease?

    <p>Plaque harboring specific bacterial pathogens (C)</p> Signup and view all the answers

    What is the focus of the Ecological Plaque Hypothesis?

    <p>Preventing disease by interfering with environmental factors driving the selection and growth of bacteria (B)</p> Signup and view all the answers

    How does the Ecological Plaque Hypothesis propose to prevent disease?

    <p>By interfering with environmental factors driving the selection and growth of selected bacteria (D)</p> Signup and view all the answers

    What is the role of keystone species such as P. gingivalis in the development of inflammatory disease?

    <p>They trigger inflammation even in low numbers, influencing the environment (C)</p> Signup and view all the answers

    What happens to keystone pathogens when disease reaches an advanced stage?

    <p>They are detected in higher numbers (B)</p> Signup and view all the answers

    What is one of the exceptions to Koch’s Postulates?

    <p>Microorganisms that are unable to be cultured on artificial media (C)</p> Signup and view all the answers

    What is one of Socransky’s proposed criteria for judging potential periodontal pathogens?

    <p>Must be associated with disease, as evident by increase in the number of organisms at diseased site (D)</p> Signup and view all the answers

    What is a local dietary factor that affects plaque formation?

    <p>Intake of fermentable carbohydrates (sucrose) (B)</p> Signup and view all the answers

    Which iatrogenic factor affects plaque formation by creating restorative margin issues?

    <p>Iatrogenic Factors that Affect Plaque Formation (D)</p> Signup and view all the answers

    What is the primary distinguishing feature of Grade 3 plaque according to the Plaque Index?

    <p>Abundance of plaque within gingival pocket or on the tooth and gingival margin (C)</p> Signup and view all the answers

    Where is wrong about plaque formation occur faster according to the variations in dentition of plaque?

    <p>Buccal/ Palatal Surface &gt;Interdental Areas (D)</p> Signup and view all the answers

    What does Grade 2 plaque indicate according to the Plaque Index?

    <p>Moderate accumulation of plaque within gingival pocket or on the tooth and gingival margin (D)</p> Signup and view all the answers

    What are the components of chronic inflammation in gingival inflammation?

    <p>B and T Lymphocyte (A)</p> Signup and view all the answers

    What defines Dental Plaque Induced Gingivitis?

    <p>Inflammatory lesion resulting from interactions between dental plaque biofilm and host’s immune inflammatory response (B)</p> Signup and view all the answers

    What are the clinical features of Dental Plaque Induced Gingivitis?

    <p>Redness of gingival tissue, Bleeding on probing, Changes in contour (C)</p> Signup and view all the answers

    What is the characteristic of Grade 3 gingival inflammation according to the Gingival Index?

    <p>Severe inflammation, marked redness, edema, ulceration, spontaneous bleeding (B)</p> Signup and view all the answers

    What is the defining feature of Grade 2 gingival inflammation according to the Gingival Index?

    <p>Moderate inflammation, redness, edema, glazing, and bleeding on probing (A)</p> Signup and view all the answers

    How is Grade 1 gingival inflammation defined according to the Gingival Index?

    <p>Mild inflammation, slight color change, slight edema, no bleeding on probing (D)</p> Signup and view all the answers

    Study Notes

    Microbial Biofilm and Oral Infections

    • The primary cause of dental caries, gingivitis, periodontitis, and peri-implant infections is the microbial biofilm.
    • A biofilm is defined as a diverse microbial community embedded in a matrix.
    • The matrix is composed of 70-80% water, 10-15% carbohydrates, 5-10% proteins, and 1-5% lipids.
    • Microorganisms make up 10-15% of dental plaque (biofilm).
    • The inorganic content of the extracellular matrix in dental plaque is primarily hydroxyapatite.
    • The organic content of the extracellular matrix in dental plaque includes lipids, proteins, and carbohydrates.

    Dental Plaque and Calculus

    • Intrinsic tooth stains are primarily caused by the presence of dental plaque.
    • Materia Alba is a deposit composed of dead bacteria, leukocytes, and debris.
    • Materia Alba can be easily removed from tooth surfaces with a disclosing agent.
    • The primary inorganic component of calculus is hydroxyapatite.
    • The organic content of calculus includes lipids, proteins, and carbohydrates.
    • Calculus is composed of 70-80% hydroxyapatite and 20-30% organic content.

    Biofilm Formation and Adhesion

    • Conditioning film forms on the tooth surface within minutes after cleaning.
    • The conditioning film reaches equilibrium after 2 hours.
    • Reversible adhesion in bacterial adhesion is characterized by electrostatic and van der Waals interactions.
    • Irreversible adhesion in bacterial adhesion is characterized by specific interactions.
    • Secondary and late colonizers adhere in co-adhesion through specific interactions.
    • Stage 3 of biofilm formation results in the formation of a matrix.
    • New outer membrane components in Stage 3 of biofilm formation facilitate the development of synergistic and antagonistic interactions.

    Bacterial Interactions and Adaptation

    • Gradients in nutrients and fermentation products within the plaque result in spatial and temporal variations in bacterial metabolism.
    • The metabolism of microorganisms during biofilm formation results in the production of fermentation products.
    • Some species of bacteria respond to deteriorating conditions by detaching and colonizing elsewhere.
    • The adaptive response of bacteria to changes in their environment is characterized by the formation of a biofilm.
    • Superoxide dismutase, Catalase, and Peroxidase enzymes are responsible for neutralizing toxic Superoxides and Hydrogen Peroxides in bacteria.
    • Oxygen can be harmful to some bacteria that do not produce these enzymes.

    Bacterial Types and Respiration

    • Anaerobic bacteria can use anaerobic respiration to survive without oxygen.
    • Aerobic bacteria require oxygen to live.
    • Facultative bacteria can use both aerobic and anaerobic respiration to survive.
    • Gram-negative bacteria have an outer lipopolysaccharide membrane.
    • Gram-positive bacteria have a thick peptidoglycan layer in their cell wall.
    • Gram-negative bacteria have a less acidic cell wall due to the presence of lipopolysaccharides.

    Oral Disease and Microbiota

    • The transition to oral disease is associated with a shift in the microbiota towards a more pathogenic community.
    • Commensal microbiota promote oral health by preventing the colonization of pathogens.
    • Specific bacterial species, such as Streptococcus sanguinis and Streptococcus oralis, are positively associated with oral health.
    • The orange complex species, including Fusobacterium nucleatum and Prevotella intermedia, are associated with periodontal disease.
    • The absence of beneficial organisms in a biofilm can contribute to the development of oral disease.

    Quorum Sensing and Biofilm Formation

    • Quorum sensing is a mechanism of bacterial communication that allows bacteria to coordinate their behavior.
    • Quorum sensing plays a role in biofilm formation and the development of synergistic and antagonistic interactions.
    • Quorum sensing allows bacteria to adapt to changes in their environment.
    • Obligatory anaerobic bacteria can survive in an aerobic environment within a biofilm due to the formation of a matrix.

    Periodontal Disease and Hypotheses

    • The Non-specific Plaque Hypothesis proposes that periodontal disease results from the accumulation of plaque and the elaboration of noxious products.
    • The Specific Plaque Hypothesis proposes that specific periodontal pathogens are responsible for periodontal disease.
    • The Ecological Plaque Hypothesis proposes that periodontal disease results from a shift in the microbiota towards a more pathogenic community.
    • The Ecological Plaque Hypothesis proposes that disease can be prevented by promoting a healthy microbiota.

    Gingivitis and Inflammation

    • Dental Plaque Induced Gingivitis is defined as inflammation of the gingiva caused by dental plaque.
    • The clinical features of Dental Plaque Induced Gingivitis include redness, swelling, and bleeding.
    • Grade 3 plaque according to the Plaque Index is characterized by a thick, visible plaque.
    • Grade 2 plaque according to the Plaque Index indicates a moderate amount of plaque.
    • Grade 1 gingival inflammation according to the Gingival Index is defined as mild inflammation.
    • Grade 2 gingival inflammation according to the Gingival Index is defined as moderate inflammation.
    • Grade 3 gingival inflammation according to the Gingival Index is defined as severe inflammation.

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    Test your knowledge of dental plaque and biofilm with this quiz. Learn about the diverse microbial community found on tooth surfaces, its impact on oral health, and its role in causing dental caries, gingivitis, periodontitis, and peri-implant infections.

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