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Questions and Answers
The majority of oral bacteria are harmless commensals under normal circumstances.
The majority of oral bacteria are harmless commensals under normal circumstances.
True
What is the name of the thin layer that forms on tooth surfaces within the first minute after exposure to saliva?
What is the name of the thin layer that forms on tooth surfaces within the first minute after exposure to saliva?
Pellicle
What is the primary cause of caries, gingivitis, periodontitis, peri-implantitis, and sometimes bad breath?
What is the primary cause of caries, gingivitis, periodontitis, peri-implantitis, and sometimes bad breath?
Which of the following is NOT a structural feature of biofilms?
Which of the following is NOT a structural feature of biofilms?
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Biofilms are more resistant to antimicrobial agents than their planktonic counterparts.
Biofilms are more resistant to antimicrobial agents than their planktonic counterparts.
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What is the process called when epithelial cells are shed from the mouth?
What is the process called when epithelial cells are shed from the mouth?
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What is the primary characteristic that makes teeth and implants unique from a microbiological perspective?
What is the primary characteristic that makes teeth and implants unique from a microbiological perspective?
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What is the name of the process by which bacteria attach to each other in a biofilm?
What is the name of the process by which bacteria attach to each other in a biofilm?
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Which of the following types of bacteria are more likely to predominate in mature plaque compared to early plaque?
Which of the following types of bacteria are more likely to predominate in mature plaque compared to early plaque?
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Match the following terms with their corresponding descriptions:
Match the following terms with their corresponding descriptions:
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What is the main difference between supragingival plaque and subgingival plaque from a microbiological perspective?
What is the main difference between supragingival plaque and subgingival plaque from a microbiological perspective?
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What is the primary source of inorganic constituents in supragingival plaque?
What is the primary source of inorganic constituents in supragingival plaque?
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The composition of subgingival plaque is primarily influenced by the depth of the pocket.
The composition of subgingival plaque is primarily influenced by the depth of the pocket.
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What are the three phases of dental plaque biofilm accumulation?
What are the three phases of dental plaque biofilm accumulation?
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The salivary pellicle is a passive structure that simply provides a surface for bacterial attachment.
The salivary pellicle is a passive structure that simply provides a surface for bacterial attachment.
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Which of the following bacteria are considered the primary colonizers of tooth surfaces?
Which of the following bacteria are considered the primary colonizers of tooth surfaces?
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What is the term for the type of bacterial interaction that involves two or more bacterial species attaching to each other?
What is the term for the type of bacterial interaction that involves two or more bacterial species attaching to each other?
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The transition from early dental plaque to mature plaque is characterized by a shift from primarily gram-negative bacteria to gram-positive bacteria.
The transition from early dental plaque to mature plaque is characterized by a shift from primarily gram-negative bacteria to gram-positive bacteria.
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Provide an example of coaggregation that commonly occurs in mature plaque.
Provide an example of coaggregation that commonly occurs in mature plaque.
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The early colonizers of dental plaque are primarily anaerobic bacteria.
The early colonizers of dental plaque are primarily anaerobic bacteria.
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What is the primary energy source for gram-positive early colonizers of dental plaque?
What is the primary energy source for gram-positive early colonizers of dental plaque?
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What is the term for the interaction between different species of bacteria in a biofilm, where one species benefits from the metabolic products of another?
What is the term for the interaction between different species of bacteria in a biofilm, where one species benefits from the metabolic products of another?
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The formation of dental plaque is primarily influenced by the topography of the tooth surface.
The formation of dental plaque is primarily influenced by the topography of the tooth surface.
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Which type of plaque is considered most important in the development of gingivitis?
Which type of plaque is considered most important in the development of gingivitis?
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Supragingival plaque is primarily responsible for root caries.
Supragingival plaque is primarily responsible for root caries.
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What type of plaque is associated with tissue destruction and the development of periodontitis?
What type of plaque is associated with tissue destruction and the development of periodontitis?
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Which of the following is NOT a factor that affects the composition of subgingival plaque?
Which of the following is NOT a factor that affects the composition of subgingival plaque?
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What is the difference between materia alba and calculus?
What is the difference between materia alba and calculus?
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Subgingival plaque can be easily removed by rinsing or with a water spray.
Subgingival plaque can be easily removed by rinsing or with a water spray.
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Which of the following is NOT a factor that affects the topography of supragingival plaque?
Which of the following is NOT a factor that affects the topography of supragingival plaque?
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Early plaque formation on teeth typically follows a distinct topographic pattern.
Early plaque formation on teeth typically follows a distinct topographic pattern.
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The presence of tooth irregularities can alter the typical topographic pattern of plaque formation.
The presence of tooth irregularities can alter the typical topographic pattern of plaque formation.
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Study Notes
Biofilm and Periodontal Microbiology
- Biofilm and periodontal microbiology is a key topic, covering the 13th edition of Newman and Carranza's Clinical Periodontology, chapter 8 (pages 112-150).
- The oral cavity contains 1.3 to 10 times more bacteria than human cells.
- Most oral bacteria are harmless commensals under normal circumstances.
- Increased bacterial mass and/or pathogenicity, suppression of commensal or beneficial bacteria, and/or reduced host response can lead to disease.
- Oral flora has beneficial bacteria that maintain oral harmony, but a shift in the balance triggers periodontal disease.
- The oral cavity is a complex ecosystem with different niches, including intraoral/supragingival hard surfaces, subgingival regions, buccal/palatal epithelium, tongue dorsum, tonsils, and saliva.
- Bacteria need to adhere to soft or hard surfaces to survive in the oropharynx.
- Desquamation, swallowing, mastication, or blowing the nose, and oral hygiene implement help remove oral bacteria.
- The ability of bacteria to adhere to the host is crucial for gingivitis and periodontitis.
- There is a positive correlation between the adhesion rate of pathogenic bacteria to different epithelia and susceptibility to infections.
- About 700 species of oral bacterial microbiome reside in adults.
- First colonizers of the cavity include Streptococcus salivarius, Streptococcus mitis, Veillonella spp., Neisseria spp., and Actinomyces spp.
- Periodontal microbiota is extremely complex.
- Teeth and implants are unique microbiologically because they provide a hard, non-shedding surface for bacterial deposits and form a unique ectodermal interruption between the external environment and the internal body parts.
- Bacterial biofilms in the oral cavity are composed of extracellular matrix substances, such as polysaccharides and proteins.
- Biofilms are 1000 times more resistant to antimicrobial agents than planktonic bacteria.
- Bacteria within biofilms facilitate metabolic interactions among different bacteria and compete in ways by producing antibacterial molecules like inhibitory peptides and hydrogen peroxide.
- Biofilms provide advantages for colonizing species through protection from competing microorganisms, environmental factors, and host defenses, toxic substances, facilitating nutrient uptake, removing harmful metabolites, and developing an appropriate physico-chemical environment.
- Common biofilm structural features include microcolonies of bacterial cells, water channels (primitive circulatory systems), and heterogeneous distribution with differing microenvironments (oxygen, pH).
- Bacteria are found in host tissues, such as soft tissues, epithelial cells, and dentinal tubules.
Oral Cavity
- The oral cavity is crucial in the initiation and development of gingivitis and periodontitis.
Plaque
- Plaque formation involves the initial steps of pellicle formation on the tooth's surface, followed by initial bacterial adhesion/attachment and colonization/plaque maturation.
- Plaque composition varies based on location (supragingival/subgingival).
- Supragingival plaque is stratified and multilayered; Gram-positive cocci and rods are prevalent on the tooth surface, while gram-negative rods, filaments, and spirochetes predominate in the outer layers of mature plaque.
- Subgingival plaque differs significantly in composition, driven by local factors like blood product availability and a low redox potential (anaerobic environment).
- Early plaque formation occurs at gingival margins and interdental spaces.
- Tooth surface topography influences plaque formation. Irregularities lead to more favorable growth paths.
Factors Affecting Plaque Formation
- Early plaque formation on teeth follows a typical pattern, initially forming along gingival margins and interdental areas, then extending coronally.
- Plaque formation in areas protected from shear forces is favored.
Metabolism of Dental Plaque Bacteria
- The shift from gram-positive to gram-negative bacteria during plaque development is paralleled by a physiological shift.
- Early colonizers use oxygen and lower the redox potential, favoring anaerobic species growth.
- Gram-positive colonizers use sugars as energy sources and mature plaque bacteria use amino acids and small peptides instead.
- Metabolic interactions are commonplace among bacteria in plaque.
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Description
Explore the intricate dynamics of biofilms and periodontal microbiology as detailed in chapter 8 of the 13th edition of Newman and Carranza's Clinical Periodontology. Discover how bacterial balance in the oral cavity influences gum health and the complex ecosystem of oral flora. Understand the role of both commensal and pathogenic bacteria in periodontal disease development.
