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Oral Microbiology!!! > L14-18....Caries > Flashcards

L14-18....Caries Flashcards

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1
Q

What is this theory called? Some plaque bacteria are capable of fermenting suitable dietary carbohydrate substrates to produce acid, causing plaque pH to fall below critical levels. Repeated exposure to acid pH in time may result in demineralization at susceptible sites on the tooth surface, thus initiating the carious process.

A

Acidogenic Theory

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2
Q

What are the four factors that are needed for a carious lesion to occur?

A

1.Microorganisms 2.Metabolic Substrates 3.Teeth and their environment 4.Time

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3
Q

What do we mean by Quality of microorganisms when looking at carious lesion factors?

A

Which bugs are there? How many CARIOGENIC bugs are present. That will have an effect on formation of caries.

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4
Q

What do we mean by Quantity of microorganisms when looking at carious lesion factors?

A

the number of bacteria present

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5
Q

What do we mean by Quality of substrate when looking at carious lesion factors?

A

Is the Pt eating SIMPLE sugars?

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6
Q

What do we mean by Quantity of substrate when looking at carious lesion factors?

A

Just the total amount of sugar eaten

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7
Q

What do we mean by Quality of time when looking at carious lesion factors?

A

The frequency the Pt eats sugar though out the day

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8
Q

What do we mean by Quantity of time when looking at carious lesion factors?

A

How long does the Pt keep the sugar in their mouth?

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9
Q

What do we mean by Quality of teeth & environment when looking at carious lesion factors?

A

How big are the pits and fissures/areas for bugs to develop, how good is your saliva?

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10
Q

What do we mean by Quantity of teeth & environment when looking at carious lesion factors?

A

How many teeth do you have left? (Dr. M’s uncle story)

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11
Q

What are the 4 ingredients of tooth hard tissue?

A
  1. Organic matrix 2. Minral 3.Water 4. cells (dentin)
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12
Q

What is the main component of the organic matrix of the teeth?

A

protein (collagen)… then theres other organic stuff: mucopolysaccharides, chondroitin sulfate, etc.

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13
Q

What are the three components to the mineral portion of the dental hard tissue? What is an example of each?

A

1.Hydroxyapatite (ca, po4, oh) 2.positive ions (lead, zinc, strontium) 3.Negative ions (carbonate, FLOURIDE)

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14
Q

What percent by weight is the amount of mineral in the enamel? Organic? water?

A

95% mineral (4% orgainic, 1% h2o)

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15
Q

What percent by weight is the amount of mineral in dentin? organic? water?

A

70% mineral…20%organic….10%water

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16
Q

What is the formula for hydroxyapatite?

A

Ca10(PO4)6(OH)2

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17
Q

What does a more perfect hydroxyapatite do for chemical strength and physical strength?

A

Physically, a more perfect crystal can open the door to fracture on a plane of the crystal…Chemically, a more perfect crystal is better protection from acid…so what gives???

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18
Q

What does Flouride replace in the hydroxyapatite? Why does it make enamel stronger?

A

F- is replacing the central OH-…Makes enamel stronger because it has a stronger pull on the surrounding Ca2+ molecules. (magnets!)

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19
Q

What is the most common substitute for PO4^(2-) in enamel?

A

CO3^(2-)

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20
Q

What TYPE of bonds are keeping the atoms together in hydroxyapatite?

A

ionic (non-covalent)

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21
Q

What is a substitute for Calcium in hydroxyapatite?

A

lead, strontium, radium

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22
Q

Draw me the demineralization rxn of hydroxyapatite…what is the critical pH for this reaction to happen?

A

Ca10(PO4)6(OH)2 + 14H&raquo_space;«10Ca2+ + 6(h2po4)- + 2h2o…….critical pH = 5.5

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23
Q

Why is having juice with Ca2+ beneficial to enamel?

A

Using Le Chatlier’s principle, adding Ca2+ to the unmineralized side of the equilibrium reaction will drive the reaction toward remineralization of the enamel

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24
Q

How many months does it take for sound enamel to develop a carious lesion? How long does the lesion take to get to the dentin? How long from the dentin to the pulp? How much time does it take to reach dentin when fluoride is involved?

A

formation 6 mo—->to dentin 78 months (w/ F- 104mo)—–>to pulp FAST

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25
Q

What % of patients have white spot lesions/caries because of the use of braces?

A

80%

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26
Q

What is the main point about susceptible places for caries to develop on a tooth?

A

Sites with limited access to saliva!

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27
Q

How can you remove the pellicle layer on the tooth? How long does it take to come back?

A

Cleaned off only with meticulous cleaning, it takes minutes to hours to form again

28
Q

What are the two primary carbohydrate polymers found in plaque?

A

1.Glucans (glucose polymer) and 2. Fructans (fructose polymer)

29
Q

What % of the US population struggle with eating disorders?

A

10%

30
Q

What are the two products when plaque bacteria are feed simple sugars?

A
  1. H+ 2.Extracellular polymers: Glucans and Fructans
31
Q

_________: plaque biofilm in which inorganic deposits have caused mineralization. Greatly increases risk for developing periodontitis.

A

Calculus

32
Q

What are the 3 mechanisms by which Fluoride strengthens enamel?

A
  1. Most electronegative element, so holds the hydroxyapatite structure tighter 2. Lowers CO3 content (making hydroxap. more acid resistant) 3.Binds to and poisons key metabolic enzymes in bacteria
33
Q

If the critical pH for demineralization of enamel is 5.5, what does the presence of Fluoride do to that critical pH?

A

Fluoride makes the enamel more resultant to acid, it is now 4.9 before demineralization occurs

34
Q

Does an GERM FREE animal develop caries when you feed it a high cariogenic diet?

A

NO!

35
Q

What is an animal with NO oral bacteria or KNOWN oral bacterial called?

A

g-NO-to-biotic

36
Q

After doing “add back” experiments to gnotobiotic animals to see which bacteria are most cariogenic, which ones are capable of developing caries?

A

1.S. Mutans (primary) 2.Lactobacillus 3. Actinomyces

37
Q

Experiments conducted with gnotobiotic animals have shown that caries is an _________.

A

infectious disease

38
Q

BIG CONCEPT, will definitely be on EXAM….What are the 7 properties of S. Mutans that make it so cariogenic?

A

1.Fimbrae 2. Can absorb CHO at low pH 3.Homolactic Fermenter 4.Aciduricity(able to live at low pH) &Acidophilic 5.Glucan production(more specifically ‘mutan’) 6.intracellular snacks (polysaccharide) and extracellular snacks (LEVAN) 7. Bacteriocins

39
Q

What 2 things does the production of glucans do for S. Mutans?

A

Decreases saliva’s buffering ability and increases acid [ ]

40
Q

What does the graph look like when taking a core sample of a newly erupted tooth and measuring [F-] in the three tissues?

A

It is a flat horizontal line, indicating that [F-] has evenly been distributed though out the dentin and enamel.

41
Q

As someone ages, and has been living in a place with Flouridated water, what does the [F-] graph look like in the enamel and dentin?

A

Enamel has high [F-] on the surface, but decreases as you get closer to dentin. THEN increases once again once you get closer to the pulp!

42
Q

How many lactic acid molecules are produced for each monosaccharide S. Mutans ferments?

A

2 lactic acid molecules (3C’s each) for each 1 monosaccharide (6C’s each)

43
Q

What enzyme does Fluoride inhibit and thus ‘poison’ the S. Mutans? What is the other substance that blocks this enzyme?

A

blocks ENOLASE (converts monosaccharide to PhosphoEnol Pyruvate, therefore no PEP to then be converted to pyruvate!)……..Xylitol also does this!

44
Q

What is the enzyme that breaks sucrose to then build a glucose polymer chain called Mutan (aka Glucan, dextran)?

A

Glucosyl-Transferase (unique to S. Mutans)

45
Q

What is the enzyme that breaks sucrose down into glucose and fructose on the membrane of S. Mutans?

A

InVerTase

46
Q

What is the S.Mutans membrane enzyme that breaks sucrose and then builds an extracellular fructose snack food chain? What is the chain called? What enzyme breaks down this chain?

A

FructoSyl - Transferase…..Chain is called Levan….the Levan is broken apart by Levanase

47
Q

What is the intracellular food storage for S.Mutans? What is the extracellular food storage for S. Mutans?

A

Intra: Glycogen Extra: Levan

48
Q

What are the two bacteria that convert the lactic acid product of S. Mutans to different products? What are the 2 products?

A

Neisseria and Veillonella (Gram - cocci)…they make CO2 and Acetate

49
Q

Which is more cariogenic: Sucrose or HighFructose Corn syrup?

A

Surcose…HFCS does not make Mutan/Glucan!! the glucosyl-transferase only makes mutan with sucrose

50
Q

In ‘healthy’ plaque ______ and _______ are found in very low numbers.

A

S. Mutans and Lactobacillus

51
Q

The table shows that plaque taken from active caries sites has a higher percentage of mutans Streptpcoccus, Actinomyces spp., and Lactobacillus spp. This is an example of __________ __________ from bacteria that succeed at more neutral pH to those that succeed at more acid pH (i.e., cariogenic bacteria are acidophilic)

A

bacterial succession

52
Q

What are the 4 major locations for carious lesions? What is an example of the culprit at each site?

A
  1. Pits&fissures (S.Mutans) 2.Smooth surface caries (S.Mutans) 3. Dentin (Lactobacillus Acidophilus) 4.Root (L.A. or Actin. Is.)
53
Q

________ infections are usually mixed infections of various gram-negative anaerobic bacteria.

A

Endodontic

54
Q

_________ & __________ are caused primarily by gram-negative anaerobic bacteria.

A

Gingivitis & periodontitis

55
Q

Throughout most of history coronal (enamel) _____ has been infrequent.

A

caries

56
Q

The _____ the pKa = the stronger the acid.

A

the LOWER the pKa = the stronger the acid

57
Q

In terms of pKa, why is lactic acid the most cariogenic? What is its pKa?

A

it has a pKa=3.8 and is ALMOST the lowest (Formic acid is lower, but breaks down QUICKLY to CO2 and H2O)

58
Q

A _______ Curve shows the pH drop in plaque that accompanies a glucose rinse. (the more plaque the closer you start to critical pH)

A

Stephan Curve

59
Q

What happens when you don’t brush after exposure to a glucose rinse and then give ANOTHER glucose rinse?

A

You go back below critical pH! not good for mineralization.

60
Q

Rank these sugars from most effect on oral pH to least effect: raw starch, cooked starch, sorbitol, lactose, sucrose.

A
  1. Sucrose 2.Lactose 3. Cooked starch 4.raw starch 5.sorbitol
61
Q

What does the science tell us about spreading out meals as opposed to eating three distinct meals?

A

Spreading out meals gets the oral cavity below critical pH MORE FREQUENTLY then eating all at once.

62
Q

Saliva: a mucoid coating on oral mucous membranes forms _______ barrier and ______ insulator

A

chemical….thermal

63
Q

What is ingestion of too much F-?

A

Actue Fluoride Poisoning

64
Q

What are the 5 ways saliva reduces tendency to caries?

A

1.Fush away CHO 2. Ca2+ and PO4- 3.antimicrobial agnates 4.chemical buffer 5. has recycled F-

65
Q

What is the main effect of a lack in saliva (xerostomia)?

A

increased tendency to caries

66
Q

What are the three main causes of xerostomia? What are the two main treatments?

A

disease, drugs and sleep….drink more water, chew saliva inducing gum

67
Q

What type of increase in [H+] needs to happen to lower the pH to 5.5?

A

A 15 fold increase!

Oral Microbiology!!! (12 decks)

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