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Operative > Dental Caries > Flashcards

Dental Caries Flashcards

1
Q

a naturally occurring isomorphous mineral group which contains repeats of the same crystal lattice and molecular structure of Ca5(PO4)3X

A

apatite

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2
Q

In the body, apatite is referred to as __________ and is a major component of tissues such as enamel, dentin, and bone.

A

biological apatite

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3
Q

What can X be?

Ca5(PO4)3X

A

Hydroxyl (OH-) –> hydroxyapatite
Fluoride (F-) –> fluorapatite
Chloride (Cl-) –> chlorapatite

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4
Q

Biological apatite is most commonly found as ________.

A

hydroxyapatite (HA)
Ca10(PO4)6(OH)2

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5
Q

Hydroxyapatite has an atomic arrangement of _________ cells. In its pure form, it can be found as a _________ which is biocompatible for bone implants. However, it has a _________ bioresorption rate and it does not imitate the inorganic portion of our bones and teeth.

A

hexagonal / white powder / low

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6
Q

a form of naturally occurring hydroxyapatite substituted with carbonate groups (CO3) and is the main component of enamel and dentin

A

carbonate-substituted hydroxyapatite (CHA)

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7
Q

How does HA differ from CHA?

A

carbonate substitution increases the solubility of HA and makes it more susceptible to decay

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8
Q

Tooth composition is _____% HA by volume or _____% by weight.

A

85% by volume
95% by weight

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9
Q

During amelogenesis, ameloblasts stack HA unit cells on top of each other to form crystallites that create…?

A

long enamel rods or prisms

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10
Q

orientation of enamel rods

A

keyhole pattern with a head and tail (tail has a higher organic composition with less mineral content, which makes it more susceptible to decay)

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11
Q

part of an enamel rod that is more susceptible to decay

A

tail (higher organic composition and less mineral content)

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12
Q

T or F: Enamel is structurally and compositionally the same from site to site.

A

False! Superficially, it has more fluoride substitution due to contact with fluoridated water and products. At the DEJ, it has a higher carbonate substitution. This means that the deeper a cavity penetrates, the more soluble enamel is due to the higher carbonate substitution.

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13
Q

Describe the process of caries formation.

A

In the oral cavity, Ca2+ and PO43- are constantly being transferred between the HA of the tooth and free Ca2+ and PO43- ions in the mouth and/or plaque at equilibrium.

Cariogenic bacteria digest sugars via glycolysis –> produce lactic acid as a byproduct of fermentation –> H+ ions complex with the free PO43- ions to form phosphoric acid (H3PO4) –> drives the equilibrium towards dissolution of HA –> results in the loss of Ca2+ and PO43- from the tooth –> demineralization (tooth decay)

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14
Q

The oral cavity provides an optimal environment with moisture and crevices for bacteria. This allows for growth of cariogenic bacteria which digest sugars via __________ and produce __________ as a byproduct of __________.

A

glycolysis / lactic acid / fermentation

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15
Q

states that any alterations to a system of equilibria will result in predictable opposing changes in the system to achieve a new equilibrium state

A

Le Chatelier’s Principle

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16
Q

other direct sources of acid (H+) in the mouth that can lower pH

A

food, drinks, gastric acid from GERD

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17
Q

describes the change in the pH of the oral cavity which occurs during exposure to sugars and acids as a function of time

A

Stephan curve

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18
Q

pH of the oral cavity at rest

What happens upon exposure to acid/sugars?

A

7 (neutral)

The oral pH decreases rapidly to reach a minimum value within 10 min of exposure.

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19
Q

If plaque or oral pH reaches or falls below the ________, dissolution of tooth structure begins via demineralization.

A

critical pH

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20
Q

critical pH of CHA, FA, dentin/cementum

A

CHA = 5.5
FA = 4.5
Dentin and cementum = 6.2-6.7

*The higher critical pH of dentin and cementum increases the susceptibility of exposed root surfaces to acid erosion and tooth decay.

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21
Q

acts as a natural buffer for the acidity and will neutralize the pH

A

saliva

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22
Q

How does saliva act as a natural protector against demineralization?

A

contains a weak base called bicarbonate (HCO3-) which complexes with H+ to form carbonic acid (H2CO3) –> this prevents the formation of phosphoric acid

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23
Q

How long does it take for bicarbonate in saliva to neutralize the oral pH after exposure to acids or sugars?

A

30 min

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24
Q

Saliva contains __________, which can drive the equilibrium towards HA formation (remineralization.)

A

Ca2+ ions

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25
Q

This commercial product contains buffers and increases the concentration of free minerals in saliva to shift the equilibrium towards remineralization.

A

MI paste

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26
Q

Fluoride ions in saliva from fluoridated water or oral hygiene products promote tooth remineralization through the formation of __________.

A

fluorapatite

27
Q

FA has a lower critical pH than HA. What does this mean?

A

a stronger acid challenge is required for tooth demineralization

28
Q

Which is the more stable apatite crystal? HA or FA

A

FA (stronger bond to Ca2+, increasing tooth hardness and resistance to acid damage)

29
Q

Factors that affect pH recovery after sugar or acid exposure:

A
  • bicarbonate in saliva
  • chewing sugar-free xylitol gum, as it stimulates saliva secretion w/o a drastic pH decline due to the lack of sugar
30
Q

Xerostomia patients may have a longer pH recovery time of _________ due to decreased saliva production.

A

over 1 hr

31
Q

3 ways in which FA promotes tooth remineralization:

A
  • shifting the equilibrium towards incorporation of Ca2+ and PO43-
  • decreasing enamel solubility with a lower critical pH
  • preventing the growth of cariogenic bacteria
32
Q

Caries are the result of the interaction between three things:

A
  • cariogenic bacteria (plaque)
  • tooth surfaces (host)
  • fermentable dietary carbohydrates (sugars)
33
Q

model that incorporates several modifying factors which can affect caries development

A

Keyes-Jordan model

34
Q

Progression of pit and fissure lesions? Smooth surface (and root) lesions? Dentinal lesions?

A

Pit and fissure lesions- widen into inverted V-shape as they progress deeper

Smooth surface (and root surface) lesions- wider on surface and narrows as it penetrates enamel as a V-shape

Dentinal lesions- widens again due to the higher penetrability of dentin and narrows as it deepens to form V-shape within the dentin

35
Q

most common location of smooth surface lesions

A

M/D surfaces at interproximal contacts

36
Q

This type of lesion can be remineralized when intact and is classified as a reversible white spot lesion.

A

enamel surface lesion

37
Q

An unmanaged white spot lesion may become cavitated after how long?

A

1-2 years

38
Q

A _________ lesion is classified as irreversible and requires restorative treatment.

A

cavitated

39
Q
  • bacteria loaded, superficial, mushy, soft, wet, and necrotic
  • must be completely removed prior to restoring
A

infected dentin

40
Q
  • deeper, dry, demineralized, leathery affected by bacterial toxins/acids but not invaded by bacteria
  • does NOT have to be removed during restoration as it does not contain bacteria
A

affected dentin

41
Q

caries progression

A

enamel demineraliation –> dentin demineralization –> enamel cavitation –> dentin cavitation

42
Q

Caries can be classified based on their progress (extent):

On smooth surface, appears white and opaque when air-dried and cannot be detected when wet. Occurs during enamel demineralization and some dentin demineralization stage.

A

Incipient/reversible

43
Q

Caries can be classified based on their progress (extent):

Enamel surface not intact and the lesion can progress into dentin. Occurs during enamel cavitation to dentin cavitation stage

A

Cavitated/irreversible

44
Q

Caries can be classified based on their location:

Simple-
Compound-
Complex-
Primary-
Secondary/recurrent-
Residual-

A

Simple- includes 1 surface of a tooth (occlusal most common)
Compound- includes 2 surfaces of tooth
Complex- includes 3 or more surfaces of a tooth
Primary- original caries lesion which occurs on virgin tooth surface
Secondary/recurrent- occurs at junction of tooth and restoration including small leakage under restoration, marginal gap between the tooth and restoration must be minimized to reduce bacterial penetration
Residual- caries that remain even after a tooth preparation is completed

45
Q

Caries can be classified based on progression rate:
- immediately damages tooth structure
- light-colored
- very infectious
- soft

A

acute/rampant

46
Q

Caries can be classified based on progression rate:
- demineralized tooth structure that has nearly remineralized
- discolored
- hard

A

chronic/slow

47
Q

Caries can be classified based on progression rate:
- completely arrested caries
- brown/black
- it becomes caries-resistant when exposed to fluoride
- often accompanied by sclerotic dentin that prevents bacterial ingress

A

arrested

48
Q

Arrested caries are often accompanied by _________ dentin that prevents bacterial ingress.

A

sclerotic

49
Q

hypothesis that describes caries progression that states that only specific (cariogenic) bacteria in oral cavity can lead to caries development

A

specific plaque hypothesis

50
Q

gram-positive cocci that is thought to be a major contributor to enamel caries

A

Streptococcus mutans

51
Q

S. mutans produces __________, which converts sucrose into extracellular polysaccharides (glucans and fructans) that aid with bacterial adherence to tooth.

A

glucosyltransferase (GTF)

52
Q

3 mechanisms in which S. mutans causes caries:

A
  • produces GTF
  • produces bacteriocins
  • acidogenic & aciduric
53
Q

S. mutans produces ___________ which kill off competing microbes. This allows for cariogenic biofilm (plaque) accumulation on the tooth surface which can promote caries development.

A

bacteriocins

54
Q

S. mutans is also _________, as it produces lactic acid from sucrose via fermentation. It is also ________, meaning it can also handle acidic environments without damage.

A

acidogenic / aciduric

55
Q

By the specific plaque hypothesis, the following bacteria are thought to be the main cause of:

A

Streptococcus mutans –> enamel caries
Lactobacillus –> dentinal caries
Actinomyces –> root caries

56
Q

Saliva contains several components which help to naturally protect teeth against caries. Which is this?

Dilute bacterial acid byproducts to drive equilibrium towards remineralization

A

urea and other buffers

57
Q

Saliva contains several components which help to naturally protect teeth against caries. Which is this?

Large molecules that string bacteria together to aid in their elimination during swallowing

A

glycoproteins

58
Q

Saliva contains several components which help to naturally protect teeth against caries. Which is this?

Actively binds and sequesters iron required for bacterial enzymes and function

A

lactoferrin

59
Q

Saliva contains several components which help to naturally protect teeth against caries. Which is this?

Breakdown bacterial cell walls

A

lysozyme

60
Q

Saliva contains several components which help to naturally protect teeth against caries. Which is this?

Inactivates certain bacterial enzymes

A

lactoperoxidase

61
Q

Saliva contains several components which help to naturally protect teeth against caries. Which is this?

Salivary antibodies which bind bacteria

A

sIgA (salivary IgA)

62
Q

Saliva contains several components which help to naturally protect teeth against caries. Which is this?

Used for tooth remineralization

A

Ca2+ / PO43- / F- ions

63
Q

Saliva contains several components which help to naturally protect teeth against caries. Which is this?

Proteins used for remineralization

A

statherin, cystatin, histatin, and proline rich

Operative (7 decks)

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