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Histopathology > Dentin > Flashcards

Dentin Flashcards

1
Q

What are the components of dentin?

A

70% mineral, 20% organic, and 10% qwater

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2
Q

What are the mineral parts of dentin?

A

calcium hydroxyapatite, calcium carbonate, fluoride, magnesium, and zinc

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3
Q

What are the organic parts of dentin?

A

type I collage
phosphoproteins
sialoproteins and sialophosphoproteins
proteoglycans and glycosoaminoglycans
osteonectin and osteopontin

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4
Q

What is different about the type I collagen in dentin compared to the type I collagen in bone?

A

there is a higher ratio of proline and hydroxyproline, higher prevelance of molecular cross linking, higher level of bound water, random orientation of hydroxyapatite crystals

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5
Q

What are the life cycle stage of dentin?

A

-pre-odontoblast
-secretory odontoblast
-transitional odontoblast
-resting odontoblast

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6
Q

What is the stimulus for cell differentation into pre-odontoblast?

A

comes form the basal lamina of IEE and several growth factors that are also derived from IEE

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7
Q

How do pre-odontoblastic cells align on the basal lamina?

A

there are fibronectin receptors on the pre-odontoblastic cells that align on the basal lamina (similar to a lock and key)
-then can differentiate into secretory cells

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8
Q

What are the growth factors secreted by the IEE that play a role in odontoblastic differentiation?

A

-transforming growth factor
-bone morphogenic protein
-insulin like growth factor
-fibroblast growth factor

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9
Q

Are the growth factor receptors always located on the odonotoblastic cells?

A

no
-in order to completely differentiate, the cell must divide many time in order to express the receptors to bind to each of the growth factors in IEE

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10
Q

What does the last mitotic division of dentin make?

A

results in a mature odontoblast and a daughter cell that is forced into subodontoblastic cell layer

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11
Q

What is the function of the cells in the subodontoblastic layer?

A

they remain as neural crest cells that have been exposed to all of the maturation steps for odontoblastic differentiaton
-this cell population responsible for reparative odontoblasts.

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12
Q

What is the shape of the secretory odonotblasts?

A

tall columnar cells with a lot of gap junctions

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13
Q

What type of enzyme is present in secretory odontoblasts?

A

phosphatase activity

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14
Q

What type of collagen is secreted from secretory odontoblast?

A

type I mostly, traces of type III and V

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15
Q

What matrix vesicles are secreted from secretory odontoblasts?

A

-phospholipids
-alkaline phosphatase
-phosphoproteins
-pyrohosphatase
-Ca and phosphate
-annexin
-calcium hydroxyapatite cystallines

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16
Q

What is annexin?

A

protein that mediates flow of Calcium into matrix vesicle
-also serves as collagen receptor that binds matrix vesicles to collagen

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17
Q

What is mantle dentin?

A

first formed dentin (50-100 microns thick)
-consists of type I and III collagen
-collagen arranged perpendicular to basal lamina of IEE

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18
Q

How often is organic matrix of dentin deposited?

A

every 4-20 days

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19
Q

What are the lines of von ebner?

A

incremental lines in dentin that represent hesitation in matrix formation and altered mineralization

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20
Q

What are neonatal lines/contour lines of owen?

A

deficiencies and irregularities in dentinogenesis that result in hypomineralization

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21
Q

Are dentin tubules the same width all the way down?

A

no
-they are tapered
-2.5 microns at pulpal surface
-1.2 at midlength
-0.9 near DEJ

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22
Q

What are the odontoblastic processes in the tubule?

A

out poking of dentin tubules that help with the lock and key to basal lamina

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23
Q

Which is more mineralized; peritubular or intertublar?

A

peritubular
-right outsdie the dentin tubule so has the most access to mineralization enzymes

24
Q

What is interglobular dentin?

A

zone of globular formed dentin in the crowns of teeth and in the roots
-has interglobular spaces that are unmineralized or hypomineralized dentin between normal calcified dentinal layers

25
Q

What is Tome’s granular layer?

A

granular appearing layer in the dentin of root adjacent to cementum

26
Q

What are the possible components of Tome’s granular layer?

A

hypomineralized interglobular dentin

27
Q

What is primary dentin?

A

all dentin, except mantle dentin, formed up tothe time the tooth achieves functional occlusion

28
Q

What is secondary dentin?

A

all dentin formed, except tertiary dentin, formed after the tooth achieves functional occlusion

29
Q

What is tertiary dentin?

A

dentin formed as a repair mechanism
-usually at a spot of pulpal trauma
-defense reaction

30
Q

What are dead tracts?

A

dentinal tubules that are void of the odontoblastic process
-generally filled with air or organic debris and look black

31
Q

What is sclerotic dentin?

A

dentin in which the tubules are occluded with mineral
-nontubular and nearly transparent

32
Q

When does sclerotic dentin increase in occurence?

A

as the age of the patient increases

33
Q

What are incremental lines of von ebner?

A

lines occur after 4-20 days of incremental growth of dentin
-thought to represent hesitations in matrix deposition

34
Q

What are neonatal lines and contour lines of oweb?

A

represent exaggerated lines of von ebner that occur during periods of altered cell metabolism

35
Q

What teeth do tetrocycline staining affect?

A

the part of the tooth that is developing when the medication is taken

36
Q

Can tetrocycling staining get removed?

A

no really
-grinding may help, but may make it darker

37
Q

What allow cells in the subodontoblastic layer to differentiate and form the matrix of reparative dentin?

A

exposure to growth factors released by pulpal cells
-BMP
-IGF
-FGF
-DMP

38
Q

What is dentinogenesis imperfecta?

A

hereditary defect that results in blueish gray teeth with opalescent sheen
-normal enamel
-abnormal dentin

39
Q

What do the pulp chamber and canals look like in dentinogenesis imperfecta?

A

generally obliterated by defective dentin formation

40
Q

What may be a reason the enamel does not connect to the dentin in dentinogenesis imperfecta?

A

tuftelin is missing
-there is no linking of the enamel to the dentin

41
Q

What is attrition?

A

loss by wear of surface caused by tooth to tooth contact during mastication
-matching wear on occluding surfaces

42
Q

Why is there not increased sensitivity with attrition?

A

the pulp cavity can be filled in with reparative dentin

43
Q

What is erosion?

A

loss of hard dental tissue by chemical processes
-only the tooth degrades, the restoration remains
-common in GERDpatients

44
Q

What is the core of hydroxyapatite crystals?

A

relatively more soluble carbonate apatite
-can be eroded by acids more quickly

45
Q

What can substitute the hydroxyl ions in hydroxyapatite?

A

fluoride

46
Q

What are the bacterium responsible for caries?

A

-streptococcus mutans (enamel/dentin caries)
-streptococus sorbrinus (enamel/dentin)
-streptococcus gordonii (enamel/dentin)
-lactobacillus acidophils (enamel/dentin)
-actinomyces viscosus (root caries)

47
Q

How does acid dissolution of enamel spread laterally?

A

branching of dentinal tubules at the DEJ
-allow penetration toward the pulp

48
Q

What is the shape of caries lesion in the dentin?

A

a pyramidal shape with apex pointing toward the pulp

49
Q

What can be done to help avoid cavities in teeth that have deep pits and fissures?

A

pit and fissure sealantsW

50
Q

What teeth are most commonly affected with sensitivty?

A

canines and premolars (cuspids and bicuspids)

51
Q

What are stimuli associated with dentinal sensitivity?

A

-cold or hot beverages
-sweet or sour foods and drinks
-overly aggressive brushing
-acidogenic plaque bacteria
-cosmetic bleaching of teeth
-clenching and bruxism

52
Q

Why can teeth feel sensitivty?

A

free nerve endings in the dentinal tubules

53
Q

What is the direct innervation theory?

A

direct stimulation of nerve endings in dentinal tubules

54
Q

What is the transduction theory?

A

stimulation of odontoblasts that are couple to nerves in the pulp

55
Q

What is the Brannstrom’s hydrodynamic theory?

A

(most prevelant theory)
-stimulation of dentinal thubules of exposed odontoblastic cell processes causes movement of tissue fluids within dentinal tubules that stimulate nerve endings in close association with dentin and dentin/pulpal interface

-basically there is fluid that presses on nerve stuff and causes pain

56
Q

What is charles law?

A

volume of gas is directly proportional to the amount of heat applied at a constant pressure

57
Q

How does charles law apply to teeth?

A

if heat is applied to a sensitive tooth, the volume of the tubule increase, causing the stimulation of nerve endings
if cold is applied to a sensitive tooth, the volume of the tubule decreases, still causing movement of fluid and stimulation of nerve ending

Histopathology (13 decks)

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