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7 Cards in this Set
- Front
- Back
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Is saliva a good culture medium?
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No
-Because it contains few nutrients and contains antibacterial substances such as lysozyme and lactoperoxidase -Lysozyme - weakens the bacterial cell walls by cleaving the glycosidic linkages in the peptidoglycan -Lactoperoxidase kills bacteria in a reaction that generates singlet oxygen |
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If saliva is such a bad culture medium, then why does the oral cavity contain many bacteria?
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-It is because the presence of food particles and epithelial debris makes the mouth a favorable habitat for a great variety of bacteria.
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How does the oral cavity become colonized?
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1) At birth, oral cavity is sterile but it becomes colonized during the first feeding
2) As the child grows, mouth presents a succession of different ecological situations (eruption of teeth, formation of gingival crevice area) and this corresponds with changes in the composition of the normal flora 3) Prior towards eruption of teeth in the child, bacterial populations of the normal flora include aerotolerant anaerobes as well as a few aerobes 4) After teeth appear, there is a shift towards anaerobes that are adapted for growth on the tooth surface and in the gingival crevices |
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When bacteria grow on tooth surfaces in thick layers, what is it called?
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Plague (this is a biofilm)
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How does dental plague formation occur?
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-It is initiated by the deposit of a thin organic film of acidic glycoproteins from the saliva
-Film is several micrometers thick and provides an attachment and colonization site for a few species of streptococcus -THe microorganisms in plague produce adherent substances (glucans) that encourage further colonization -Bacteria then multiply extensively to form a biofilm |
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What are dental caries?
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These are cavities that are the destruction of the enamel, dentin or cementum of the teeth caused by acid-producing bacteria in plague
-Lactic acid bacteria produce lactic acid from the fermentation of sugars and other carbohydrates in the diet of the host -Streptocoocus mutans has most consitently been associated with the initiation of dental caries, but other lactic acid bacteria are probably involved |
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What are peridonatal diseases?
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These are bacterial infections that affect the supporting structures of the teeth.
-Gingivitis is inflammatory condition of the gums |
