Dental Caries Overview
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Questions and Answers

What primarily causes the demineralization of enamel and dentin in dental caries?

  • Excessive dental brushing
  • Fermentation of fats
  • Fermentation of carbohydrates by bacteria (correct)
  • Absence of fluoride

    • Which of the following factors is NOT considered a contributing etiological factor in the development of dental caries?

  • Fermentable carbohydrates
  • Cariogenic bacteria
  • Presence of antioxidants (correct)
  • Time

    • Which experiment demonstrated that the absence of bacteria leads to no development of dental caries?

  • Orland’s Experiment with Gnotobiotes
  • Orland’s Experiment with Germ-free animals (correct)
  • Miller’s Experiment
  • Bradley’s Experiment with Fluorides

    • What type of bacteria was specifically shown to produce smooth surface and pit and fissure caries in Orland's Experiment?

    <p>Streptococcus mutans</p> Signup and view all the answers

    What is meant by the term 'gnotobiote' in the context of dental caries research?

    <p>An organism with a known set of microorganisms</p> Signup and view all the answers

    In dental caries, what component serves as the medium for cariogenic bacteria to act upon the tooth surface?

    <p>Dental plaque</p> Signup and view all the answers

    Which of the following describes the process of demineralization in dental caries?

    <p>Loss of inorganic components from the tooth structure</p> Signup and view all the answers

    What role do fermentable carbohydrates play in the development of dental caries?

    <p>They serve as a substrate for acid production by bacteria</p> Signup and view all the answers

    What has a greater influence on caries activity than the total amount of carbohydrates consumed?

    <p>Frequency and texture of carbohydrates</p> Signup and view all the answers

    Which form of sugar is identified as the most potent cause of dental caries?

    <p>Sticky sugars</p> Signup and view all the answers

    What is the primary composition of dental plaque by volume?

    <p>Micro-organisms</p> Signup and view all the answers

    What role does the plaque matrix serve in relation to organic acids produced in the mouth?

    <p>Retains acids in high concentrations</p> Signup and view all the answers

    Which factor is NOT mentioned as affecting plaque formation and thickness?

    <p>Quantity of saliva produced</p> Signup and view all the answers

    What is the first step in the mechanism of bacterial plaque formation?

    <p>Formation of an acquired enamel pellicle</p> Signup and view all the answers

    What thickness can the acquired enamel pellicle reach?

    <p>0.1-1.0 μm</p> Signup and view all the answers

    Which component is NOT part of the amorphous matrix in dental plaque?

    <p>Bacterial cells</p> Signup and view all the answers

    What is the role of salivary glycoproteins in dental health?

    <p>They protect the enamel surface from bacterial colonization.</p> Signup and view all the answers

    What condition is highlighted as leading to an increased rate of dental caries?

    <p>Xerostomia (lack of salivary secretion)</p> Signup and view all the answers

    Which salivary components are primarily responsible for remineralizing caries lesions?

    <p>Fluoride, calcium, and phosphate</p> Signup and view all the answers

    What is the initial macroscopic appearance of enamel caries?

    <p>Opaque chalky white area</p> Signup and view all the answers

    What is the role of the initial community in the colonization of the pellicle?

    <p>Primary colonizers like S.sanguis prepare the surface for rapid growth of other bacteria.</p> Signup and view all the answers

    What type of organisms flourish during the selective replacement within the plaque flora?

    <p>Aciduric organisms</p> Signup and view all the answers

    Which phase is not part of the development of enamel caries?

    <p>Phase of mineral absorption</p> Signup and view all the answers

    Which bacterial arrangement is referred to as ‘corn on the cobs’?

    <p>Filamentous organisms arranged parallel to each other.</p> Signup and view all the answers

    What is the primary function of secretory immunoglobulin A (sIgA) in saliva?

    <p>Killing bacteria and preventing their adherence</p> Signup and view all the answers

    What happens during the phase of bacterial invasion in enamel caries?

    <p>Acids permeate enamel, facilitating bacterial entry.</p> Signup and view all the answers

    What is the primary function of acid-producing bacteria during plaque formation?

    <p>To contribute to demineralization of the tooth surface.</p> Signup and view all the answers

    Which substance in saliva has a direct antibacterial action?

    <p>Lysozyme</p> Signup and view all the answers

    Which of the following is NOT a biochemical reaction occurring in bacterial plaque?

    <p>Production of toxic metabolites for host cells</p> Signup and view all the answers

    In what timeframe does the rapid growth phase of bacteria occur after initial colonization?

    <p>8-48 hours</p> Signup and view all the answers

    What mechanism allows Strep.mutans to attach to pioneer species during colonization?

    <p>Adhesin-receptor interactions</p> Signup and view all the answers

    What was the primary aim of Stephan's experiment?

    <p>To study the changes in pH of plaque after glucose intake.</p> Signup and view all the answers

    Which characteristic is NOT essential for a bacteria to be considered cariogenic?

    <p>Ability to photosynthesize</p> Signup and view all the answers

    What is the primary reason Lactobacillus species do not initiate caries on smooth surfaces?

    <p>They lack the ability to synthesize extracellular polysaccharides.</p> Signup and view all the answers

    Which property makes Streptococcus mutans particularly effective at initiating dental caries?

    <p>Production of extracellular polysaccharides like dextran</p> Signup and view all the answers

    Which of the following is a feature of aciduric bacteria?

    <p>Ability to thrive at low pH levels</p> Signup and view all the answers

    Which species is closely associated with the initiation of dental caries in humans?

    <p>Streptococcus mutans</p> Signup and view all the answers

    What is the function of extracellular polysaccharides like dextran in cariogenic bacteria?

    <p>To enhance attachment to tooth surfaces</p> Signup and view all the answers

    Which of the following statements about lactobacilli is true?

    <p>They can survive at a low pH of 5.4.</p> Signup and view all the answers

    What role does amylopectin play in cariogenic bacteria?

    <p>It acts as a reserve of fermentable carbohydrates.</p> Signup and view all the answers

    What is the primary purpose of using a polarized light microscope?

    <p>To determine the percentage of enamel pores by volume</p> Signup and view all the answers

    What characterizes the translucent zone in early smooth surface caries?

    <p>It is located at the advancing front of the lesion</p> Signup and view all the answers

    How does the dark zone appear under transmitted light?

    <p>Dark because smaller pores prevent quinoline penetration</p> Signup and view all the answers

    What is the significance of submicroscopic pores in enamel?

    <p>They account for 1% of total enamel volume</p> Signup and view all the answers

    What happens to the translucency of the lesion in the translucent zone as a result of alterations in enamel structure?

    <p>It retains its translucency</p> Signup and view all the answers

    Which of the following best describes microradiography?

    <p>A process that reflects the amount and distribution of minerals using black and white</p> Signup and view all the answers

    In which zone of enamel caries does further demineralization occur due to acid proximity?

    <p>Dark zone</p> Signup and view all the answers

    What is one of the causes of smaller pores forming in the dark zone?

    <p>Absence of acid production</p> Signup and view all the answers

    Infected dentinal lesions can be remineralized and should be preserved.

    <p>False</p> Signup and view all the answers

    The presence of bacteria is involved in uninfected dentinal lesions.

    <p>False</p> Signup and view all the answers

    Root surface caries are typically due to gingival recession along with bacterial invasion.

    <p>True</p> Signup and view all the answers

    Regular reactionary dentin is formed in response to mild stimuli by caries.

    <p>True</p> Signup and view all the answers

    Dead tracts in dentin result from the death of odontoblasts, creating an empty, dark appearance.

    <p>True</p> Signup and view all the answers

    The zone of fatty degeneration is a characteristic of uninfected dentinal lesions.

    <p>False</p> Signup and view all the answers

    Irregular reactionary dentin forms in response to mild stimuli.

    <p>False</p> Signup and view all the answers

    Bacteria penetrate into the superficial layer of demineralized cementum very late during root surface caries development.

    <p>False</p> Signup and view all the answers

    Saliva contains secretory immunoglobulin A (sIgA) which kills bacteria and prevents their adherence.

    <p>True</p> Signup and view all the answers

    The buffering capacity of saliva decreases with higher rates of salivary flow.

    <p>False</p> Signup and view all the answers

    Xerostomia is characterized by an increased rate of dental caries due to lack of saliva.

    <p>True</p> Signup and view all the answers

    The first phase of enamel caries is known as the phase of bacterial invasion.

    <p>False</p> Signup and view all the answers

    Increased salivary flow in individuals with mongolism may contribute to lower caries incidence.

    <p>True</p> Signup and view all the answers

    Saliva's inorganic components like calcium and phosphate promote the demineralization of enamel.

    <p>False</p> Signup and view all the answers

    During enamel caries, the process involves continuous dissolution of the enamel structure.

    <p>False</p> Signup and view all the answers

    The macroscopic appearance of initial enamel caries is characterized by a translucent zone.

    <p>False</p> Signup and view all the answers

    Caries is produced when the periods of remineralization exceed those of demineralization.

    <p>False</p> Signup and view all the answers

    Deep and narrow pits and fissures are less prone to decay than wide and shallow pits.

    <p>False</p> Signup and view all the answers

    Fluorapatite formed by fluoride is more soluble in acids compared to hydroxyapatite.

    <p>False</p> Signup and view all the answers

    Newly erupted teeth are generally more resistant to caries than older teeth.

    <p>False</p> Signup and view all the answers

    Contact areas that are point contacts are more caries resistant than board contacts.

    <p>True</p> Signup and view all the answers

    The rate of progression of caries can be affected by enamel hypoplasia and enamel hypocalcification.

    <p>True</p> Signup and view all the answers

    The initial community during bacterial colonization consists of S.sanguis and Actinomyces viscosus.

    <p>True</p> Signup and view all the answers

    Fluoride therapy can increase the fluoride content in the enamel surface, making it more resistant to caries.

    <p>True</p> Signup and view all the answers

    During the rapid growth phase, bacteria arrange themselves in a triangular formation on the tooth surface.

    <p>False</p> Signup and view all the answers

    Genetic factors play a more significant role than environmental factors in determining caries susceptibility.

    <p>False</p> Signup and view all the answers

    Aciduric organisms like Veillonella and S.mutans thrive as a result of the selective replacement within plaque flora.

    <p>True</p> Signup and view all the answers

    Filamentous organisms are predominant in the mature community of bacterial plaque within three days.

    <p>False</p> Signup and view all the answers

    Dental plaque is formed from a single type of bacterium embedded in a matrix.

    <p>False</p> Signup and view all the answers

    The process of microbial succession results in continuous replacement of microbial communities based on environmental changes.

    <p>True</p> Signup and view all the answers

    The acquired enamel pellicle is a bacteria-rich structure that forms on tooth surfaces.

    <p>False</p> Signup and view all the answers

    The peritubular hypermineralized zone narrows the diameter of the tubules to enhance bacterial invasion.

    <p>False</p> Signup and view all the answers

    Sticky sugars contribute significantly to dental caries due to their retention on teeth.

    <p>True</p> Signup and view all the answers

    Extracellular polysaccharides like Dextran and Levan are produced by primary colonizers in the plaque.

    <p>False</p> Signup and view all the answers

    The thickness of the acquired enamel pellicle can reach up to 5 μm.

    <p>False</p> Signup and view all the answers

    Stephan's experiment aimed to analyze changes in the pH of plaque following the intake of protein.

    <p>False</p> Signup and view all the answers

    The first wave of bacterial invasion in dentinal lesions consists of mixed acidogenic and proteolytic organisms.

    <p>False</p> Signup and view all the answers

    Reparative dentin is laid down around and below the peritubular hypermineralized zone in response to acid attack.

    <p>True</p> Signup and view all the answers

    Anaerobic species replace aerobic species in the deeper layers of mature dental plaque.

    <p>True</p> Signup and view all the answers

    An amorphous matrix in dental plaque comprises about 30-40% of its volume.

    <p>True</p> Signup and view all the answers

    Dental plaque acts as a diffusion barrier, which can slow attacks from bacterial acids.

    <p>True</p> Signup and view all the answers

    Transverse clefts in dentinal tubules are formed from longitudinal orientation of liquefaction foci.

    <p>False</p> Signup and view all the answers

    The widening of the dentinal tubule is a result of more acids causing demineralization.

    <p>True</p> Signup and view all the answers

    The presence of oral hygiene measures has no effect on plaque formation and thickness.

    <p>False</p> Signup and view all the answers

    Bacterial invasion in dentin occurs in a continuous manner without rest phases.

    <p>False</p> Signup and view all the answers

    Caries activity is primarily influenced by the total amount of carbohydrates consumed.

    <p>False</p> Signup and view all the answers

    Demineralization of dentin can occur passively from minerals released during the demineralization process.

    <p>True</p> Signup and view all the answers

    Microscopic observations reveal that liquefaction foci are similar in orientation and content to transverse clefts.

    <p>False</p> Signup and view all the answers

    What characteristic shape describes the early enamel lesion in smooth surface caries?

    <p>The early enamel lesion is cone-shaped, with the base on the surface and the apex towards the amelodentinal junction.</p> Signup and view all the answers

    In dental microradiography, what does the appearance of the lesion indicate about mineral distribution?

    <p>The lesion appears black and white, reflecting the amount and distribution of minerals present in the enamel.</p> Signup and view all the answers

    What role do submicroscopic pores play in the translucent zone of early enamel caries?

    <p>Submicroscopic pores account for 1% of total enamel volume and contribute to the initial demineralization.</p> Signup and view all the answers

    How does the dark zone differ from the translucent zone in early enamel caries?

    <p>The dark zone shows further demineralization and appears dark due to the presence of minute pores that scatter light.</p> Signup and view all the answers

    What is the relationship between the refractive index of the mounting medium and the appearance of the translucent zone?

    <p>The mounting medium matches the refractive index of enamel, making the translucent zone appear clear as structural features are obscured.</p> Signup and view all the answers

    What causes the dark appearance of the dark zone during transmitted light examination?

    <p>The smaller pores in the dark zone prevent quinoline from entering, causing air to scatter light and creating a brownish color.</p> Signup and view all the answers

    Which microscopy technique is used to determine the percentage of enamel pores by volume?

    <p>Polarized light microscopy is employed to measure the percentage of enamel pores.</p> Signup and view all the answers

    What implications do the characteristics of the initial enamel caries lesions have for treatment decisions?

    <p>The shape and zone characteristics indicate the progression of caries, guiding appropriate treatment interventions.</p> Signup and view all the answers

    What role do odontoblasts play in the peritubular hypermineralized zone?

    <p>Odontoblasts actively transport minerals from the blood via the pulp into the peritubular hypermineralized zone.</p> Signup and view all the answers

    How does demineralization affect the dentinal tubules during acid exposure?

    <p>Demineralization increases the diameter of the tubules, making them distended and more susceptible to bacterial invasion.</p> Signup and view all the answers

    What is the significance of reparative dentin in response to acid attacks?

    <p>Reparative dentin is laid down as a defensive response by the pulp to counteract acid attacks.</p> Signup and view all the answers

    Describe the difference between the first and second wave of bacterial invasion in dentinal lesions.

    <p>The first wave consists of acidogenic organisms called pioneers, while the second wave includes mixed acidogenic and proteolytic organisms.</p> Signup and view all the answers

    What characterizes the phenomenon of 'beading' during bacterial invasion?

    <p>'Beading' refers to the alternating active and resting phases of microorganism progress within the dentinal tubules.</p> Signup and view all the answers

    What are liquefaction foci and how do they form?

    <p>Liquefaction foci are areas within the dentinal tubules filled with microorganisms and necrotic debris that form through the coalescence of adjacent beads.</p> Signup and view all the answers

    Explain how transverse clefts differ from liquefaction foci in dentinal tubules.

    <p>Transverse clefts are formed perpendicularly to the dentinal tubules and contain similar contents to liquefaction foci.</p> Signup and view all the answers

    What is the outcome of excessive acid exposure on the dentinal tubules?

    <p>Excessive acid exposure leads to further demineralization of the tubules, increasing their diameter and making them more prone to bacterial invasion.</p> Signup and view all the answers

    What is the relationship between periods of demineralization and remineralization in the development of caries?

    <p>Caries develops when periods of demineralization exceed periods of remineralization.</p> Signup and view all the answers

    How does the morphology of teeth influence their susceptibility to caries?

    <p>Pits and fissures are more susceptible to caries due to difficulty in cleaning, with deep and narrow types being more prone to decay than wide and shallow ones.</p> Signup and view all the answers

    What role does fluoride play in dental health?

    <p>Fluoride increases enamel resistance to demineralization, enhances remineralization, and inhibits bacterial growth.</p> Signup and view all the answers

    What is the effect of newly erupted teeth on caries susceptibility?

    <p>Newly erupted teeth are more susceptible to caries, but their resistance increases over time due to post-eruptive maturation.</p> Signup and view all the answers

    How do environmental factors compare to genetic factors in influencing dental health?

    <p>Environmental factors, such as food habits and dental care practices, have a more significant impact on dental health than genetic factors.</p> Signup and view all the answers

    What types of fissures are more resistant to caries and why?

    <p>V type and U type fissures are more resistant due to their shape and depth, which are less prone to food retention than I type and Y type fissures.</p> Signup and view all the answers

    What is the significance of enamel hypoplasia in relation to dental caries?

    <p>Enamel hypoplasia affects the rate of progression of caries but does not initiate its formation.</p> Signup and view all the answers

    What is the maximum fluoride concentration recommended in drinking water to prevent caries during tooth development?

    <p>The recommended fluoride concentration in drinking water should not exceed 1.5 parts per million.</p> Signup and view all the answers

    What are the primary colonizers involved in the initial community during the colonization phase of cell-free pellicle?

    <p>The primary colonizers are <em>Streptococcus sanguis</em> and <em>Actinomyces viscosus</em>.</p> Signup and view all the answers

    How do secondary colonizers like Streptococcus mutans attach to the established pioneer species?

    <p>They attach via adhesin-receptor interactions.</p> Signup and view all the answers

    What happens to less aciduric organisms like Streptococcus sanguis during the selective replacement in plaque flora?

    <p>They disappear as aciduric organisms like <em>Veillonella</em> and <em>Streptococcus mutans</em> flourish.</p> Signup and view all the answers

    Describe the arrangement of filamentous organisms in the mature community of dental plaque.

    <p>Filamentous organisms proliferate and arrange themselves parallel to each other and at right angles to the tooth surface.</p> Signup and view all the answers

    What are the two types of polysaccharides formed in bacterial plaque?

    <p>Extracellular polysaccharides and intracellular polysaccharides are formed.</p> Signup and view all the answers

    What was the aim of Stephan's experiment regarding plaque and glucose intake?

    <p>The aim was to study the changes in pH of plaque after glucose intake.</p> Signup and view all the answers

    What occurs during the rapid growth phase (8-48 hours) of bacterial colonization?

    <p>Bacteria spread as a monolayer and then start to form palisade arrangements on the tooth surface.</p> Signup and view all the answers

    How do aerobic species change in relation to anaerobic species as plaque matures?

    <p>Aerobic species are replaced by anaerobic species in the deeper layers of the plaque.</p> Signup and view all the answers

    What are the key features that make a bacterium cariogenic?

    <p>Key features include the ability to produce acids (acidogenic), survive in acidic environments (aciduric), synthesize insoluble extracellular polysaccharides, and actively transport fermentable sugars.</p> Signup and view all the answers

    How does Streptococcus mutans adapt its morphology in response to environmental changes?

    <p>Streptococcus mutans can change its shape from round to rod under different conditions, such as a decrease in pH.</p> Signup and view all the answers

    Why can't Lactobacillus species initiate caries on smooth surfaces?

    <p>Lactobacillus species are unable to produce extracellular or intracellular polysaccharides, preventing them from effectively attaching to smooth tooth surfaces.</p> Signup and view all the answers

    What is the main role of dextran in dental plaque formation?

    <p>Dextran acts as an adhesive substance that facilitates the attachment of microorganisms to smooth tooth surfaces and forms the bulk of dental plaque.</p> Signup and view all the answers

    In what way do intracellular storage polysaccharides like amylopectin benefit cariogenic bacteria?

    <p>Amylopectin allows cariogenic bacteria to reserve fermentable carbohydrates for energy after dietary sugars are cleared away.</p> Signup and view all the answers

    What differentiates Streptococcus mutans from other cariogenic bacteria?

    <p>Streptococcus mutans is particularly effective in initiating caries due to its ability to ferment a variety of sugars and produce adhesive polysaccharides.</p> Signup and view all the answers

    What factors enable cariogenic bacteria to thrive in the mouth?

    <p>These bacteria possess mechanisms for acid production, survival in low pH, strong adhesion to tooth surfaces, and competition for fermentable sugars.</p> Signup and view all the answers

    Why is it significant that not all bacteria produce dental caries?

    <p>Understanding that not all bacteria are cariogenic helps in identifying which specific bacteria contribute to caries and informs prevention strategies.</p> Signup and view all the answers

    How does saliva contribute to the prevention of dental caries?

    <p>Saliva protects against dental caries by providing a buffering system to neutralize acids and by containing minerals like calcium and phosphate for enamel remineralization.</p> Signup and view all the answers

    What is the significance of the phase of bacterial invasion in dental caries?

    <p>The bacterial invasion phase marks the penetration of harmful bacteria into the enamel, leading to an increase in demineralization and progression of caries.</p> Signup and view all the answers

    How does xerostomia (dry mouth) affect dental health?

    <p>Xerostomia leads to an increased rate of dental caries due to reduced saliva flow, which decreases buffering capacity and protective factors against bacteria.</p> Signup and view all the answers

    Describe the microscopic changes that occur during the demineralization of enamel.

    <p>During demineralization, acids permeate the enamel, creating alternating submicroscopic changes characterized by the formation of pores.</p> Signup and view all the answers

    What purpose do salivary glycoproteins serve in oral health?

    <p>Salivary glycoproteins form the acquired enamel pellicle that protects enamel surfaces from bacterial colonization.</p> Signup and view all the answers

    What are the main inorganic components of saliva that aid in caries prevention?

    <p>The main inorganic components are calcium, phosphate, and fluoride, which diffuse into plaque and help reduce enamel solubility.</p> Signup and view all the answers

    Explain the role of secretory immunoglobulin A (sIgA) in saliva.

    <p>sIgA plays a vital role in oral immunity by preventing bacterial adherence to surfaces and inhibiting bacterial metabolic activity.</p> Signup and view all the answers

    What are the visible signs of initial enamel caries?

    <p>Initial enamel caries appear as a chalky white area, commonly referred to as a 'white spot' on the tooth surface.</p> Signup and view all the answers

    Streptococcus mutans is more ______ than lactobacilli.

    <p>cariogenic</p> Signup and view all the answers

    The ability to produce ______ is one of the essential features for a bacteria to be cariogenic.

    <p>acids</p> Signup and view all the answers

    Lactobacilli can only produce pit and fissure ______ in gnotobiote animals.

    <p>caries</p> Signup and view all the answers

    Dextrans provide a means of ______ to smooth tooth surfaces.

    <p>adhesion</p> Signup and view all the answers

    Amylopectin serves as a reserve of fermentable ______ after dietary carbohydrates have been cleared away.

    <p>carbohydrates</p> Signup and view all the answers

    Bacteria like Streptococcus mutans have ______ mechanisms for firm adhesion to tooth surfaces.

    <p>attachment</p> Signup and view all the answers

    Lactobacilli are aciduric and can survive at a low pH of ______.

    <p>5.4</p> Signup and view all the answers

    The synthesis of insoluble extracellular polysaccharides such as ______ and levan is essential for cariogenic bacteria.

    <p>dextran</p> Signup and view all the answers

    Dental plaque is a tenacious bacterial structure formed on tooth ______.

    <p>surfaces</p> Signup and view all the answers

    The plaque matrix acts as a diffusion-limiting ______, retaining organic acids in high concentrations.

    <p>membrane</p> Signup and view all the answers

    The acquired enamel pellicle is formed by selective adsorption of specific salivary ______.

    <p>glycoproteins</p> Signup and view all the answers

    Dental plaque is primarily composed of ______ and an amorphous matrix.

    <p>micro-organisms</p> Signup and view all the answers

    Factors affecting plaque formation include the anatomy of the tooth and the composition of the ______.

    <p>diet</p> Signup and view all the answers

    An acquired enamel pellicle is approximately ______ μm thick.

    <p>0.1-1.0</p> Signup and view all the answers

    The initial community in plaque formation is crucial for the ______ of the bacterial community.

    <p>colonization</p> Signup and view all the answers

    Sticky sugars are considered the most potent cause of dental ______.

    <p>caries</p> Signup and view all the answers

    The pH was recorded after two hours of the last meal and this pH is called resting ______.

    <p>pH</p> Signup and view all the answers

    Individuals were asked to rinse their mouth with 25 ml.of 10% ______.

    <p>glucose</p> Signup and view all the answers

    The curves show that after the glucose rinse, the pH drops rapidly reaching the critical pH of ______ within 2-5 minutes.

    <p>5.5</p> Signup and view all the answers

    The rapid fall in the pH is due to the activity of large numbers of bacteria and ______ in the dental plaque.

    <p>enzymes</p> Signup and view all the answers

    Dental caries consists of periods of ______ and periods of remineralization.

    <p>demineralization</p> Signup and view all the answers

    The caries susceptible patients (C.S.P) show a lower fall in pH which remains for a longer time below the ______ level.

    <p>critical</p> Signup and view all the answers

    The slow return in pH after the glucose rinse is due to the continued metabolism of residual ______ absorbed by the plaque.

    <p>sugar</p> Signup and view all the answers

    As the pH continues to drop, further caries is produced when an individual continues to consume ______ or fermentable carbohydrates.

    <p>sweets</p> Signup and view all the answers

    Sucrose is considered the arch criminal of dental ______.

    <p>caries</p> Signup and view all the answers

    Monosaccharides include ______ and fructose.

    <p>glucose</p> Signup and view all the answers

    Disaccharides like sucrose are the most ______ carbohydrates.

    <p>cariogenic</p> Signup and view all the answers

    Polysaccharides are considered less cariogenic because they are of high ______ weight.

    <p>molecular</p> Signup and view all the answers

    Lactobacilli are present in large numbers in the saliva of persons with high ______ activity.

    <p>caries</p> Signup and view all the answers

    Cariogenic bacteria, such as S. mutans, help build bacterial plaque by forming extracellular ______.

    <p>polysaccharides</p> Signup and view all the answers

    Sucrose is rapidly broken down by bacterial enzymes to produce ______.

    <p>acids</p> Signup and view all the answers

    The breakdown of polysaccharides into simple sugars is a slow process due to the action of ______.

    <p>amylase</p> Signup and view all the answers

    The phase of bacterial invasion occurs when sufficient pathways are created by the action of _____.

    <p>acids</p> Signup and view all the answers

    Loss of enamel minerals leads to loss of structure, up to ____% by volume.

    <p>90</p> Signup and view all the answers

    The lateral spread of acids at the dentino-enamel junction gives enamel a bluish-white _____.

    <p>appearance</p> Signup and view all the answers

    Dentin is composed of approximately 75% ____ phase.

    <p>mineral</p> Signup and view all the answers

    The zone of _____ degeneration occurs when acids irritate the odontoblastic processes in the tubules.

    <p>fatty</p> Signup and view all the answers

    Superficially to the zone of fatty degeneration, a zone of hyper____ is observed.

    <p>mineralization</p> Signup and view all the answers

    The initial non-bacterial lesion forms deep to carious enamel before any _____ has formed.

    <p>cavity</p> Signup and view all the answers

    Secondary enamel caries occurs when the acids reach the dentino-enamel _____.

    <p>junction</p> Signup and view all the answers

    Infected dentinal lesions are ______ and should be removed.

    <p>not remineralizable</p> Signup and view all the answers

    Uninfected dentinal lesions are ______ and should be preserved.

    <p>remineralizable</p> Signup and view all the answers

    The presence of ______ leads to the softening of infected dentinal tissues.

    <p>bacteria</p> Signup and view all the answers

    The zone of fatty degeneration is part of ______ dentinal lesions.

    <p>uninfected</p> Signup and view all the answers

    Infected dentinal lesions often contain ______ filled with microorganisms and debris.

    <p>larger cavities</p> Signup and view all the answers

    Root surface caries are usually due to exposure of the neck of the tooth to the ______ environment.

    <p>oral</p> Signup and view all the answers

    In cases of severe stimuli, the death of ______ results in empty dentinal tubules.

    <p>odontoblasts</p> Signup and view all the answers

    The basic reactions and carious destruction of root dentin are similar to that of ______ caries.

    <p>coronal</p> Signup and view all the answers

    Match the following phases of bacterial colonization with their characteristics:

    <p>Colonization phase = Primary colonizers include S.sanguis and Actinomyces viscosus Rapid growth phase = Bacteria spread as a monolayer and then in palisades Intermediate Community = Strep.mutans attaches to established pioneer species Mature Community = Filamentous organisms arrange parallel to each other</p> Signup and view all the answers

    Match the following microbial processes with their descriptions:

    <p>Acid production = Causes demineralization of tooth enamel Extracellular polysaccharides = Assist in bacterial adhesion Intracellular polysaccharides = Serve as an energy storage for bacteria Remineralization phase = Restores minerals lost from tooth enamel</p> Signup and view all the answers

    Match the following bacterial species with their roles in dental plaque:

    <p>S.sanguis = Primary colonizer that can be outcompeted Strep.mutans = Secondary colonizer that produces acid Veillonella = Flourishes in acidic conditions Lactobacilli = Contributes to the mature community in the plaque</p> Signup and view all the answers

    Match each component of biochemical reactions in bacterial plaque with its outcome:

    <p>Acid production = Leads to enamel demineralization Formation of extracellular polysaccharides = Enhances bacterial adherence Formation of intracellular polysaccharides = Provides energy reservoir Demineralization phase = Results in loss of tooth minerals</p> Signup and view all the answers

    Match the following types of interactions within the plaque flora with their outcomes:

    <p>Positive interaction = Aciduric organisms flourish Negative interaction = Less aciduric species disappear Selective replacement = Substitution of bacterial species over time Microbial succession = Dynamic changes in microbial communities</p> Signup and view all the answers

    Match the following timeframes with the associated bacterial colonization phases:

    <p>8 hours = Initial colonization phase begins 8-48 hours = Rapid growth phase occurs 2 weeks = Mature community develops Ongoing = Microbial succession continues</p> Signup and view all the answers

    Match the following substances with their roles in plaque formation:

    <p>Adhesin = Facilitates attachment of bacteria Extracellular polysaccharides = Forms a matrix for bacterial community Aciduric species = Thrives in low pH environments Aerobic species = Present in deeper layers before replacement</p> Signup and view all the answers

    Match the following terms related to Stephan's experiment with their meanings:

    <p>Caries activity groups = Classification based on susceptibility to dental caries pH changes = Measured after glucose intake Experiment aim = To assess plaque response to glucose Divided individuals = Grouped based on observed dental health</p> Signup and view all the answers

    Match the following types of carbohydrates with their characteristics regarding cariogenicity:

    <p>Monosaccharides = Less cariogenic, simple sugars Disaccharides = Most cariogenic, rapidly metabolized Polysaccharides = Less cariogenic, high molecular weight Sucrose = Arch criminal of dental caries</p> Signup and view all the answers

    Match the following enzymes with their corresponding reactions:

    <p>Invertase = Hydrolysis of sucrose to fructose and glucose Glucokinase = Phosphorylation of glucose Fructokinase = Phosphorylation of fructose Glucosyltransferase = Production of dextran from glucose</p> Signup and view all the answers

    Match the following substances with their roles in dental caries:

    <p>Dextran = Extracellular polysaccharide from glucose Levan = Extracellular polysaccharide from fructose Amylase = Breaks down polysaccharides into simple sugars Acids = Byproducts of bacterial metabolism leading to demineralization</p> Signup and view all the answers

    Match the following attributes with their corresponding carbohydrates:

    <p>Sucrose = Cheap and available carbohydrate Glucose = Simple sugar, easily metabolized Starch = Complex carbohydrate, high molecular weight Fructose = Simple sugar, present in fruits</p> Signup and view all the answers

    Match each type of bacteria with its role in dental caries:

    <p>Streptococcus mutans = Pioneer organism in caries initiation Lactobacillus = Indicator of caries activity Cariogenic bacteria = Producers of extracellular polysaccharides Bacterial enzymes = Break down sucrose to produce acids</p> Signup and view all the answers

    Match the following features of carbohydrates with their cariogenic potential:

    <p>Low molecular weight = Allows rapid diffusion into dental plaque High molecular weight = Restricts quick diffusion into plaque Rapid breakdown = Increases acid production Slow metabolism = Decreases cariogenic potential</p> Signup and view all the answers

    Match the following polysaccharides with their characteristics:

    <p>Starch = Less cariogenic due to slow breakdown Glycogen = Limited cariogenicity, complex structure Dextran = Cariogenic due to bacterial synthesis Cellulose = Not easily metabolized by bacteria</p> Signup and view all the answers

    Match the following steps with their processes in carbohydrate metabolism:

    <p>Hydrolysis = Breaking down of sucrose Glycolysis = Conversion of glucose to organic acids Fermentation = Production of acids from carbohydrates Transport = Movement of simple sugars into the cell</p> Signup and view all the answers

    Match the roles of saliva with their descriptions:

    <p>Salivary glycoproteins = Protect enamel from bacterial colonization Salivary buffers = Neutralize acidity caused by sugar metabolism Inorganic components = Promote remineralization of caries lesions Secretory immunoglobulin A (sIgA) = Kill bacteria and prevent their adherence</p> Signup and view all the answers

    Match the phases of enamel caries development with their descriptions:

    <p>Phase of initiation = Initial signs of enamel degradation Phase of bacterial invasion = Bacteria penetrate the enamel Phase of destruction = Significant loss of enamel integrity Phase of secondary enamel caries = Recurrent decay following initial restoration</p> Signup and view all the answers

    Match the following features with the corresponding bacteria:

    <p>Streptococcus mutans = Synthesis of dextran and levan Lactobacillus species = Cannot attach to smooth surfaces</p> Signup and view all the answers

    Match the appearance of caries with their classification:

    <p>Opaque chalky white area = Initial enamel caries Submicroscopic pores = Dynamic changes in dentin caries Translucent zone = Early smooth surface caries Dark zone = Area of further demineralization</p> Signup and view all the answers

    Match the salivary components with their functions:

    <p>Calcium = Reduces solubility of enamel Fluoride = Strengthens enamel against decay Lysozyme = Direct antibacterial agent Lactoferrin = Binds iron to inhibit bacterial growth</p> Signup and view all the answers

    Match the following characteristics with their descriptions:

    <p>Acidogenic = Ability to produce acids Aciduric = Ability to survive in an acidic environment Insoluble extracellular polysaccharides = Aid in adhesion to tooth surfaces Intracellular storage polysaccharides = Reserve fermentable carbohydrates</p> Signup and view all the answers

    Match the following acids with their associated bacteria:

    <p>Lactic acid = Streptococcus mutans Acetic acid = Lactobacillus species Propionic acid = Lactobacillus species Butyric acid = Streptococcus mutans</p> Signup and view all the answers

    Match the conditions related to saliva and dental health:

    <p>Xerostomia = Increased rate of dental caries Increased salivary flow = Reduced incidence of caries in mongolism Salivary buffers = Resist pH drops from acid production sIgA = Inhibition of bacterial metabolism</p> Signup and view all the answers

    Match the methods to identify initial enamel caries with their descriptions:

    <p>Longitudinal ground section = Used for detailed microscopic analysis Visual examination = Identifies white spot lesions Transillumination = Detects subsurface caries Radiographic analysis = Evaluates caries extent and depth</p> Signup and view all the answers

    Match the following statements about cariogenic bacteria:

    <p>Streptococcus mutans = Initiates caries in humans Lactobacillus species = Ferments a limited range of sugars</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Gnotobiote = Organism-free environment for testing Cariogenic = Causing dental caries Plaque pellicle = Initial bacterial layer on teeth Aciduric = Surviving low pH environments</p> Signup and view all the answers

    Match the primary factors contributing to caries with their implications:

    <p>Plaque accumulation = Bacterial growth and acid production Diet high in sugar = Enhanced fermentation leading to decay Saliva quality = Buffering and protective effects on enamel Oral hygiene practices = Prevent plaque and caries formation</p> Signup and view all the answers

    Match the caries-preventive actions of saliva with their mechanisms:

    <p>Buffering capacity = Neutralizes plaque acidity Cleansing effect = Removes food particles and bacteria Mineral diffusion = Supports enamel remineralization Antibacterial substances = Directly inhibit microbial growth</p> Signup and view all the answers

    Match the following sugar transport mechanisms with their descriptions:

    <p>Active transport = Transporting against a concentration gradient Facilitated diffusion = Transporting along a concentration gradient Passive transport = No energy required for sugar movement Group translocation = Chemical modification during transport</p> Signup and view all the answers

    Match the following polysaccharides with their roles:

    <p>Dextran = Adhesion to smooth tooth surfaces Levan = Storage of carbohydrates Amylopectin = Reserve of fermentable carbohydrates Glycogen = Storage for energy</p> Signup and view all the answers

    Match the following bacteria with their ability to produce dental caries:

    <p>Streptococcus mutans = Produces extracellular polysaccharides Lactobacillus species = Cannot synthesize extracellular polysaccharides</p> Signup and view all the answers

    Match the following factors with their descriptions related to dental caries:

    <p>Susceptible Tooth Position = Alignment and location of teeth affecting caries susceptibility Pits and Fissures = More prone to decay due to difficulty in cleaning Enamel Hypoplasia = Affects the rate of progression but not initiation of caries Fluoride Mechanism = Inhibits bacterial growth and enhances remineralization</p> Signup and view all the answers

    Match the following types of pits and fissures with their caries resistance levels:

    <p>V type and U type = More caries resistant I type = Less resistant to caries Y type = Prone to decay Wide and shallow pits = More resistant to caries</p> Signup and view all the answers

    Match the following fluoride supply sources with their characteristics:

    <p>Water = Should not exceed 1.5 parts per million Tea = Contains fluoride Seafood = Source of fluoride Topical application = Used post-eruption for caries prevention</p> Signup and view all the answers

    Match the following genetic factors with their influences on dental caries:

    <p>Favorable morphology = Inherited tooth characteristics Environmental factors = Food habits and dental care from family Genetic factors = Less influential than environmental factors Tooth structure = Affects caries susceptibility due to heredity</p> Signup and view all the answers

    Match the following actions of fluoride with their effects on dental caries:

    <p>Increasing enamel resistance = Fluoride replaces hydroxyl group in hydroxyapatite Enhancing remineralization = Fluoride promotes regeneration of mineral content Inhibiting bacterial growth = Fluoride reduces bacterial enzyme activity Cariostatic effect = Fluoride increases resistance to dental caries</p> Signup and view all the answers

    Match the following types of teeth with their susceptibility to caries:

    <p>Newly erupted teeth = More susceptible to caries Properly aligned teeth = Less caries susceptibility Malposed teeth = More prone to decay Deep pits = Higher risk for caries development</p> Signup and view all the answers

    Match the following characteristics of caries-resistant teeth with their descriptions:

    <p>Increased fluoride content = Enhances resistance to caries Post eruptive maturation = Leads to improved enamel strength Point contact = More resistant than board contacts Wide pits = Less susceptible to decay</p> Signup and view all the answers

    Match the following descriptions of dental caries mechanisms with their functions:

    <p>Demineralization = Loss of minerals from tooth surface Remineralization = Restoration of minerals via saliva or fluoride Bacterial growth inhibition = Fluoride action reducing microbial activity Cariostatic effect of fluoride = Prevents caries development through structural changes</p> Signup and view all the answers

    Match the following terms with their definitions or descriptions:

    <p>Resting pH = pH recorded after no fermentable carbohydrates are consumed for two hours Stephan's Curve = A graph plotting pH values against time after a glucose rinse Demineralization = The process of mineral loss from teeth due to acid Remineralization = The process of restoring minerals to the tooth enamel</p> Signup and view all the answers

    Match the following patient types with their characteristics:

    <p>Caries Resistant Patients (C.R.P) = Show a shorter duration of lower pH after glucose exposure Caries Susceptible Patients (C.S.P) = Experience a greater drop in pH and longer time below critical pH Rapid pH Drop = Occurs within 2-5 minutes after glucose rinse Slow pH Return = Takes about one hour to return to resting levels after sugar intake stops</p> Signup and view all the answers

    Match the following pH-related phenomena with their causes:

    <p>Rapid fall in pH = Due to rapid diffusion of sugar into dental plaque Slow return to resting pH = Due to continued metabolism of residual sugar and delayed diffusion Critical pH = The pH level below which demineralization occurs (5.5) Caries activity = Higher with longer duration of pH below critical level</p> Signup and view all the answers

    Match the following processes with their order in dental caries development:

    <p>Initial sugar intake = Leads to rapid drop in pH Acid production = Results from bacterial metabolism of sugars Demineralization = Occurs when pH falls below critical levels Remineralization = Happens when sugar intake stops and oral hygiene improves</p> Signup and view all the answers

    Match the timeframes with the respective pH measurements following glucose rinse:

    <p>2 minutes = Initial drop in pH recorded 5 minutes = Further assessment of pH after the rinse 10 minutes = Continuation of pH measuring, approaching resting pH levels 30 minutes = Monitoring pH to observe return dynamics after glucose rinse</p> Signup and view all the answers

    Match the following contributions to pH changes with their descriptions:

    <p>Sugar diffusion = Quickly alters the plaque environment Bacterial activity = Major contributor to acid production in dental plaque Salivary buffers = Slowly diffuse into plaque to help neutralize acids Acid diffusion = Limited by dental plaque's properties</p> Signup and view all the answers

    Match the following pH recovery factors with their functions:

    <p>Oral hygiene = Establishes conditions for remineralization post sugar intake Dietary adjustments = Reduces further acid exposure from fermentable carbohydrates Bacterial metabolism = Continues to affect pH levels after sugar is removed Salivary flow = Aids in the neutralization of acid through buffering</p> Signup and view all the answers

    Match the following conditions with their results on dental health:

    <p>Frequent sugar intake = Prolonged low pH and increased caries risk Inadequate oral hygiene = Exacerbates demineralization and plaque accumulation Regular tooth brushing = Facilitates remineralization and improves pH balance Limited carbohydrate consumption = Supports quicker return to resting pH levels</p> Signup and view all the answers

    What happens when periods of remineralization exceed periods of demineralization?

    <p>The lesion becomes resistant</p> Signup and view all the answers

    What genetic factors influence tooth morphology and its susceptibility to caries?

    <p>Genetically inherited factors</p> Signup and view all the answers

    Fluoride replaces the hydroxyl group in hydroxyapatite forming __________, which is less soluble in acids.

    <p>fluorapatite</p> Signup and view all the answers

    Match the following types of fissures with their caries resistance:

    <p>V type = More caries resistant U type = More caries resistant I type = Less caries resistant Y type = Less caries resistant</p> Signup and view all the answers

    Which of the following factors is considered more influential than genetic factors in the susceptibility to dental caries?

    <p>Environmental factors</p> Signup and view all the answers

    Topical fluoride application is effective after the eruption of teeth.

    <p>True</p> Signup and view all the answers

    Name one main action of fluoride in preventing dental caries.

    <p>Inhibits bacterial growth</p> Signup and view all the answers

    Which of the following bacteria is capable of producing pit and fissure caries?

    <p>Lactobacillus species</p> Signup and view all the answers

    All bacteria produce dental caries.

    <p>False</p> Signup and view all the answers

    What is the primary reason Streptococcus mutans is associated with the initiation of caries in humans?

    <p>Its ability to synthesize extracellular polysaccharides dextran and levan.</p> Signup and view all the answers

    Streptococcus mutans is more cariogenic than __________.

    <p>Lactobacillus species</p> Signup and view all the answers

    Match the following properties to the cariogenic bacteria that exhibit them:

    <p>Streptococcus mutans = Produces extracellular polysaccharides Lactobacillus species = Can produce pit &amp; fissure caries only Both = Acidogenic and aciduric</p> Signup and view all the answers

    Which of the following features is NOT essential for a bacteria to be considered cariogenic?

    <p>Ability to survive in an alkaline environment</p> Signup and view all the answers

    Lactobacillus species have the ability to produce both extracellular and intracellular polysaccharides.

    <p>False</p> Signup and view all the answers

    Dextran acts as a barrier to the diffusion of acids from __________.

    <p>plaque</p> Signup and view all the answers

    Which of the following factors is NOT a contributing factor to dental caries?

    <p>Genetic Factors</p> Signup and view all the answers

    The production of caries-like lesions can occur in the absence of bacteria.

    <p>False</p> Signup and view all the answers

    What type of environment did Orland's experiment create to study dental caries?

    <p>Aseptic environment</p> Signup and view all the answers

    Dental caries leads to the demineralization of the inorganic portion of the tooth and destruction of the _______ substance.

    <p>organic</p> Signup and view all the answers

    Match the type of caries to the corresponding bacteria:

    <p>Streptococcus mutans = Smooth surface caries Lactobacilli = Pit and fissure caries Staphylococci = Not primarily associated with caries Actinomyces = Root caries</p> Signup and view all the answers

    What is a primary source of minerals in the peritubular hypermineralized zone?

    <p>Active transport by odontoblasts from blood via the pulp</p> Signup and view all the answers

    Which experiment initially suggested that caries result from the fermentation of carbohydrates by bacteria?

    <p>Miller’s Experiment</p> Signup and view all the answers

    The zone of hypomineralization results in a decrease in the diameter of dentinal tubules.

    <p>False</p> Signup and view all the answers

    What type of organisms make up the second wave of bacterial invasion?

    <p>Mixed acidogenic and proteolytic organisms</p> Signup and view all the answers

    What key role do cariogenic bacteria play in the process of dental caries?

    <p>Producing acids</p> Signup and view all the answers

    Gnotobiotes are those animals that are maintained in a germ-free environment.

    <p>True</p> Signup and view all the answers

    The ____________ phase refers to the alternating active and resting phases of micro-organisms during bacterial invasion.

    <p>beading</p> Signup and view all the answers

    Match the following zones with their characteristics:

    <p>Peritubular hypermineralized zone = Protects against acid attack Zone of hypomineralization = Increased tubule diameter Zone of bacterial invasion = Characterized by microbial aggregates Infected dentinal lesion = Develops after enamel cavity formation</p> Signup and view all the answers

    What is the primary result of the liquefaction foci and transverse clefts?

    <p>Formation of larger, distended segments within dentinal tubules</p> Signup and view all the answers

    Reparative dentin is formed as a defense reaction of the pulp against acid attack.

    <p>True</p> Signup and view all the answers

    What occurs as a result of bacterial invasion in the dentin?

    <p>Development of an infected dentinal lesion</p> Signup and view all the answers

    What is the primary effect of acid on dentin during the early stages of caries?

    <p>Irritation of odontoblastic processes</p> Signup and view all the answers

    The phase of secondary enamel caries involves the lateral spread of acids reaching the enamel.

    <p>True</p> Signup and view all the answers

    What percentage of the mineral phase is found in dentine?

    <p>75%</p> Signup and view all the answers

    In an uninfected dentinal lesion, the first zone affected by acid attack is the zone of ______.

    <p>Fatty Degeneration</p> Signup and view all the answers

    Match the phase of caries development with its description:

    <p>Phase of Bacterial Invasion = Creates sufficient pathways for bacterial access Phase of Destruction = Loss of enamel minerals and structural integrity Phase of Secondary Enamel Caries = Lateral spread of acids affecting dentin Uninfected Dentinal Lesion = Deep lesion affected by acids without bacterial infection</p> Signup and view all the answers

    What major effect occurs to enamel when acids reach the dentino-enamel junction (DEJ)?

    <p>Enamel loses support from dentin</p> Signup and view all the answers

    The zone of hypermineralization lies superficially to the zone of fatty degeneration in dentinal lesions.

    <p>True</p> Signup and view all the answers

    Describe the appearance of enamel when secondary caries occurs.

    <p>Bluish-white appearance</p> Signup and view all the answers

    What happens to infected dentinal lesions?

    <p>They are not remineralizable.</p> Signup and view all the answers

    Uninfected dentinal lesions involve the presence of bacteria.

    <p>False</p> Signup and view all the answers

    What changes occur in dentin as a reaction to caries?

    <p>Tubular sclerosis, dead tract, regular reactionary dentin, irregular reactionary dentin.</p> Signup and view all the answers

    In root surface caries, the _____ junction presents a bacterial retention site.

    <p>enamel-cementum</p> Signup and view all the answers

    Match the following types of dentinal lesions with their descriptions:

    <p>Infected dentinal lesion = Not remineralizable and should be removed Uninfected dentinal lesion = Remineralizable and should be preserved Tubular sclerosis = Decreases size of dentinal tubules Dead tract = Empty dentinal tubules from dying odontoblasts</p> Signup and view all the answers

    Which zone is NOT found in uninfected dentinal lesions?

    <p>Pioneers</p> Signup and view all the answers

    Root surface caries develop due to gingival recession exposing the neck of the tooth.

    <p>True</p> Signup and view all the answers

    What is the primary factor leading to microbial invasion in root surface caries?

    <p>Exposure of the enamel-cementum junction.</p> Signup and view all the answers

    Study Notes

    Dental Caries Definition

    • Dental caries is a progressive microbial disease affecting hard tooth structures.
    • It is characterized by the demineralization of the inorganic portion and destruction of the organic substance of the tooth.

    Etiology of Dental Caries

    • Contributing factors to dental caries include:
      • Cariogenic bacteria
      • Fermentable carbohydrates
      • Susceptible tooth and saliva
      • Time
      • Means of localization of microorganisms and substrate on tooth surfaces (dental plaque).

    Cariogenic Bacteria

    • Cariogenic bacteria produce acids from the fermentation of carbohydrates.
    • These acids lead to demineralization of enamel and dentin.
    • Bacteria like Streptococcus mutans are more cariogenic than Lactobacilli. Streptococcus mutans are also acidogenic and aciduric, fermenting a variety of sugars, and are highly acid tolerant, closely associated with caries initiation.
    • Lactobacillus species are also acidogenic and aciduric, and capable of producing pit and fissure caries, but less so in smooth surface caries.
    • Streptococcus mutans are associated with the initiation of caries and contribute to the formation of extracellular polysaccharides.

    Miller's Experiment

    • Miller's work demonstrated the role of caries-like lesions produced by incubating teeth in saliva with added carbohydrates.
    • He suggested that the process results from carbohydrate fermentation by bacteria in saliva.
    • The resulting acid leads to enamel and dentin demineralization.

    Orland's Experiment

    • Aim: To determine if bacteria is essential for dental caries.
    • Method: Pregnant rats were placed in sterile environments and divided into two groups: one group in sterile conditions, the other under normal conditions.
    • Both were fed cariogenic diets.
    • Result: The group maintained under sterile conditions (bacteria free) did not develop dental caries.

    Production of Gnotobiotes (Germfree animals)

    • Aim: To identify specific bacteria causing dental caries.
    • Method: Germ-free rats were fed cariogenic diets containing different types of bacteria (streptococci, lactobacilli, etc.).
    • Observation: Only rats fed cariogenic diets containing Streptococcus mutans developed smooth-surface caries.

    Essential Features for Cariogenic Bacteria

    • Ability to produce acids (acidogenic)
    • Ability to survive in an acidic environment (aciduric)
    • Synthesis of insoluble extracellular polysaccharides (dextrans and levan)
    • Synthesis and utilization of intracellular storage polysaccharides (amylopectin)
    • Ability to actively transport fermentable sugars
    • Attachment mechanisms for firm adhesion to tooth surfaces

    Streptococcus Mutans

    • Able to ferment a variety of sugars (acidogenic)
    • Very acid-tolerant; can survive in low pH environments (aciduric)
    • Synthesizes extracellular polysaccharides (dextran and levan), enabling adhesion.
    • Key role in the initiation of caries.

    Lactobacillus Species

    • Acidogenic and aciduric.
    • Capable of producing pit and fissure caries in certain animal models but not as significant in smooth surface caries.
    • Not all bacteria produce dental caries.

    Role of Fermentable Carbohydrates

    • Carbohydrate types vary in cariogenicity, with sucrose (due to low molecular weight and rapid breakdown to acids) being particularly important.
    • Sticky carbohydrates remain in the mouth longer, increasing the cariogenic effect.
    • Carbohydrate refining increases cariogenicity due to a higher concentration of fermentable carbohydrates.

    Vipeholm Experiment

    • This experiment investigated the effects of amount, frequency, and texture of carbohydrates on dental caries.
    • Results suggested that frequent intake and sticky carbohydrates caused more widespread caries.
    • Further, eating sticky carbohydrates, like candies, between meals, was associated with highest caries activity.

    Dental Plaque Composition

    • Microorganisms (60-70% volume)
    • Amorphous matrix (30-40% volume) (proteins, carbohydrates, inorganic materials)
    • Plaque is a biofilm
    • Plaque is a tenacious bacterial structure formed on tooth surfaces that consists of a diverse community of bacteria embedded within an extracellular matrix.

    Plaque Matrix Role

    • Acts as a diffusion-limiting membrane: retains produced acid in high concentration.
    • Contributes to adhesiveness and resists being washed away by saliva.

    Factors Affecting Plaque Formation/Thickness

    • Tooth anatomy and position
    • Presence of appliances
    • Tooth surface structures
    • Friction from food (chewing)
    • Oral hygiene
    • Diet

    Mechanism of Plaque Formation

    • Formation of acquired enamel pellicle
    • Colonization of cell-free pellicle by bacteria (initiation and intermediate communities leading to a mature community)

    Microbial Succession

    • Replacement of microbial communities over time in response to environmental changes.

    Biochemical Reactions in Plaque

    • Acid production
    • Formation of extracellular polysaccharides
    • Formation of intracellular polysaccharides
    • Demineralization
    • Remineralization

    Stephan's Experiment

    • Recorded changes in pH of plaque following glucose intake.
    • Caries susceptibility related to length of time pH remained below critical level (5.5).

    Demineralization and Remineralization

    • Periods of demineralization and remineralization are dynamic processes during caries.
    • Remineralization occurs when sugar intake ceases and oral hygiene is improved.
    • Excessive demineralization leads to caries development; remineralization can halt or stop progression.

    Host Factors (Susceptible Tooth):

    • Dental position and alignment
    • Tooth morphology (pits and fissures are more susceptible than smooth surfaces; deep narrow fissures more susceptible)
    • Presence of restorations (crowding)
    • Tooth structure (enamel hypoplasia, enamel hypocalcification)
    • Fluoride content (higher fluoride content leads to greater resistance)

    Saliva

    • Specific salivary glycoproteins initially protect enamel.
    • Saliva flow cleanses the mouth and neutralizes acids produced in the plaque.
    • Reduced saliva flow can increase caries risk.

    Pathology of Dental Caries

    • Macroscopic appearance: white spot lesions
    • Microscopic appearance: alternating demineralization-remineralization periods leading to caries.
    • Stages of dental caries: initiation, bacterial invasion, destruction, secondary enamel caries
    • Methods of identifying initial enamel caries (using light microscopy, polarization microscopy, or microhardness testing or micro-radiography).
    • Zones of enamel caries: translucent zone, dark zone, body of the lesion, representing demineralization. Also includes zones of hypermineralization (sclerosis) and hypomineralization (demineralized).
    • Stages and zones of dentinal caries (initial, infected, and destruction), detailing the zones of demineralization, hypermineralization and fatty degeneration are also detailed. Include the formation of transverse clefts, which are perpendicular to the dentinal tubules, and the liquefaction foci, which are longitudinal

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    Dental Caries Handout PDF

    Description

    This quiz explores the definition and etiology of dental caries, detailing its progressive nature and the role of cariogenic bacteria. It highlights the factors contributing to dental decay and discusses Miller's experiment that illustrates the process of demineralization of tooth structures. Test your understanding of these concepts and their implications for oral health.

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