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DHS2🎐 > dentin(✿◡‿◡) > Flashcards

dentin(✿◡‿◡) Flashcards

covered everything❤️

1
Q

what does dentin form in tooth

A

bulk of tooth , providing shape and structure also its the only living hard tissue in body “ vital”

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2
Q

dentin location

A

beneath enamel and covered by cementum in root

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3
Q

what are the junctions of dentin with other dental tissues

A

-dentin meets enamel at DEJ which is scalloped for strong attachment

-dentin meets cementum at DCJ which is less distinct and may be smooth

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4
Q

what is the dentin -pulp complex

A

dentin and pulp are closely related embryologically , histologically , and functionally forming integrated complex

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5
Q

how does pulp contribute to dentin

A

pulp provides vitality to dentin and stimulates dentin formation

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6
Q

is dentin cellular or acellular

A

cellular contains odontoblastic processes

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7
Q

does dentin have ability to repair itself

A

yes through secondary and tertiary dentin formation

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8
Q

is dentin vascular or avascular

A

avascular

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9
Q

what color is the dentin

A

light yellow and darkens with age due to the continuous deposition of secondary dentine

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10
Q

why is dentine flexible

A

because it contains collagen and this helps prevent enamel fracture by absorbing masticatory forces

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11
Q

how does dentin resistant to wear compare to enamel

A

dentin is less resistant to attrition , abrasion, and erosion than enamel

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12
Q

how does dentin permeability change over time

A

decreases with age due to narrowing of dentinal tubules

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13
Q

what is the radiographic appearance of dentin

A

dentin appears more radiolucent than enamel but more radiopaque than pulp

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14
Q

what are the compressive strength and tensile strengths of dentin compared to enamel

A

enamel: high compressive strength, low tensile strength

dentin: high tensile strength , low compressive strength

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15
Q

what is the chemical composition of dentin

A

70% inorganic
20% organic
10% water

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16
Q

what is main inorganic component of dentin and its chemical formula

A

hydroxyapatite crystals ( smaller than enamel) Ca10(PO4)6(OH)2

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17
Q

what are the organic components of dentin

A

90% collagen fibrils( Type I, III,V)
10% non collagenous proteins and lipids

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18
Q

what are the proteins found in the organic portion of dentin

A

dentin phosphoprotein
dentin sialoprotein
dentin matrix protein
osteonectin
osteocalcin
osteopontin
bone sialoprotein
proteoglycans

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19
Q

what is the role of collagen in dentin

A

provides rigidity
Type I acts as scaffold for mineral deposition

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20
Q

what is the function of phosphoproteins in dentin

A

binds calcium and collagen
initiate crystal formation

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21
Q

what is the function of sialoprotein

A

inhibit crystal growth in peritubular dentin to prevent tubule occlusion

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22
Q

what’s the function of phospholipids

A

role in mineralization and in pre dentin and dentin

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23
Q

what are the results from DSPP mutation

A

dentinogesnsis imperfecta

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24
Q

how do proteoglycans contribute to dentin mineralization

A

more in predentin, prevents premature mineralization until collagen reach their final dimension

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25
Q

compare enamel and dentin hardness

A

enamel: is the hardest in body, 97 % mineralized

dentin : less hard than enamel but harder than cementum and bone, 65% -70% mineralized

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25
Q

what is role of enzymes in dentin

A

catalyze reactions in dentin matrix

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26
Q

what gives dentin its yellowish color

A

its composition and mineralization which is less dense than enamel

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27
Q

what is a unique property of secondary dentin

A

its formed throughout life

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28
Q

what is the role of growth factors in dentin

A

induce tertiary dentin production

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29
Q

how does dentin contribute to tooth sensitivity

A

dentin contains tubules connected to pulp which can transmit sensations of pain and sensitivity

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30
Q

how does dentin permeability impact dental treatment

A

it allows therapeutic agents applied to its surface to diffuse toward pulp aiding in treatments like remineralization

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31
Q

what are the main categories of dentin according to time of formation

A

primary dentin ( predentin , mantle dentin , circumpulpal dentin)
secondary dentin

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32
Q

what are types of dentin related to dentinal tubules

A

peritubular dentin and intertubular dentin

33
Q

what types of dentin form in response to injury

A

tertiary dentin ( reparative and reactionary)
sclerotic dentin
dental tract

34
Q

what is sclerotic dentin and when does it form

A

Sclerotic dentin forms when dentinal tubules become occluded with minerals, usually due to aging or chronic irritation

35
Q

what is dead tract in dentin

A

its an area where dentinal tubules lose their odontoblastic processes due to damage or death of odontoblast often appearing dark under microscope

36
Q

define interglobular or globular dentin

A

type of dentin characterized by areas of incomplete or defective mineralization

37
Q

what is primary dentin

A

dentin formed during initial development of tooth and ending when root formation is complete

38
Q

what are layers of primary dentin

A

outermost is mantle
main bulk is circumpulpal dentin

39
Q

reactionary dentin

A

forms from original odontoblast cells in response to mild irritation

40
Q

reparative dentin

A

formed by newly recruit odontoblast like cells after significant damage

41
Q

what triggers secondary dentin formation

A

begins after root formation is complete with continuous deposition of dentin

42
Q

how does secondary dentin affect pulp chamber

A

causes pulp chamber to decrease in size over time

43
Q

what structural difference exist between primary and secondary dentin

A

secondary dentin has fewer tubules and a demarcation line between secondary and primary dentin

44
Q

what is the clinical significance of secondary dentin deposition in elderly people

A

as secondary dentin is deposited the pulp horn recede and in elderly patients this reduces the chance of pulp exposure during cavity prep (So, even though it shrinks the pulp space, it’s making a thicker protective layer to help prevent pulp exposure if the tooth gets damaged.)

45
Q

what is mantle dentin

A

outermost layer of dentin , closest to enamel just below DEJ

46
Q

what is the thickness of mantle dentin

A

20 microns

47
Q

what unique fibers are found in mantle dentin

A

kroffs fibers which is large collagen fibers of type III

48
Q

where is predentin located

A

layer closest to pulp

49
Q

is pre dentin mineralized

A

no its nonmineralized

50
Q

how thick is predentin

A

2-6 microns

51
Q

what happens to predentin overtime

A

it mineralizes to become circumpuulpal dentin with new predentin forming beneath it

52
Q

what triggers formation of tertiary dentin

A

injury to tooth, such as caries, attrition, abrasion, or cavity prep

53
Q

how does rate of tertiary dentin formation relate to severity of injury

A

rate of deposition is related to severity of injury

54
Q

where is the tertiary dentin located

A

it can form anywhere along the pulp-dentin complex

55
Q

characteristics of tertiary dentin

A

fewer dentinal tubules
irregular arrangement
may contain no tubules or have cellular inclusions (osteodentin)

56
Q

how many dentinal tubules and its more where

A

number varies from 30,000-70,000 and its more in crown than root

57
Q

what is the diameter of dentinal tubules

A

broader(3 μm) near pulp and narrower (1μm) near enamel

58
Q

dentinal tubules are extension of what

A

extension of odontoblast processes in pulp into DEJ and DCJ

59
Q

what is the shape of dentinal tubules

A

curved ( S shape)

60
Q

what are the two types of branching in dentinal tubules what does it do

A

lateral branching (canaliculi) its 1μm in diameter and terminal branching and they allow permeability of dentin and pathways for microbial invasion

61
Q

what are the curvature of dentinal tubules

A

primary curvature: represent odontoblast movement toward pulp during dentinogensis which is less prominent in roots and straight in incisal edge, cusps, and root tips

secondary curvature: minor curvature representing daily odontoblast movement during dentogensis

62
Q

what are the components of dentinal tubules

A

odontoblastic processes ( microtubule and filaments )
dentinal fluid
thin nerve fibers
peritubular dentin
lamina limitans ( organic lining rich in gag serves as junction between peritubular and dentin tubules)

63
Q

what are enamel spindles

A

extensions of odontoblastic processes into enamel crossing DEJ

64
Q

how do enamel spindles form

A

odontoblasts fail to withdraw quickly across DEJ during dentin so they get trapped

65
Q

what is interglobular dentin

A

zones of hypomineralized dentin due yo incomplete fusion of mineral globules

66
Q

what are other secondary causes of interglobular dentin

A

vitamin D deficiency during dentin formation and increased fluoride content

67
Q

where is the interglobular dentin found

A

circumpulpal beneath mantle dentin

68
Q

define Tomes granular layer and located where

A

granular layer in dentin at DCJ caused by intermingling or looping of tubules

69
Q

how does Tomes granular layer appear

A

black granules, clearer in ground section, increases from CEJ to toot apex

70
Q

what are dead tracts

A

dark areas in dentin due to complete loss of odontoblastic processes from tubules so becomes filled with AIR and seen in older teeth

71
Q

how do they appear

A

Black in transmitted light
White in reflected light

72
Q

what causes dead tracts

A

attrition
severe injury

73
Q

what do we have below dead tracts

A

tertiary dentin

74
Q

sclerotic dentin

A

tubules occluded with minerals to protect pulp its appears glassy and transparent seen in elderly teeth and especially roots

75
Q

Incremental lines of Von ebner

A

rhythmic deposition of dentin at rate 4μm/day and these lines are 20μm apart representing 5 days of deposition

lines occurs due to slight change in collagen and the lines run perpendicular to tubules

76
Q

neonatal line

A

line separating prenatal which is better quality and postnatal dentin

found in deciduous teeth and 1st permanent molars

77
Q

contour lines of OWEN

A

dark bands caused by deficiencies in mineralization due to illness or metabolic changes

78
Q

is contour lines periodic like Von ebner lines

A

NOOOOO. cuz the contour lines occur due to specific events not periodic deposition like von ebner.

79
Q

what is direct innervation theory

A

that stimuli directly affect the nerve endings in dentinal tubules

but the mechanism is unknown since nerve ending only extend only till inner dentin

80
Q

what is transduction theory

A

that the odontoblast which originate from neural crest cells act as receptor and stimuli excite odontoblastic processes which will make impulses transmit to nerve endings.

this theory not widely accepted cuz of the absence of neurotransmitter vesicles in odontoblast

81
Q

what is fluid hydrodynamic theory

A

most widely accepted
stimuli causes fluid movement within dentinal tubules and this movement disturbs nerve endings associated with odontoblast processes triggering PAIN through MECHANICAL DISTURBANCE

DHS2🎐 (8 decks)

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