dentin

studied byStudied by 0 people
0.0(0)
get a hint
hint

What forms the bulk of the tooth?

1 / 144

encourage image

There's no tags or description

Looks like no one added any tags here yet for you.

145 Terms

1

What forms the bulk of the tooth?

dentin

New cards
2

what provides the general shape & form of tooth

dentin

New cards
3

what is dentin covered by

Enamel of anatomic crown Cementum of anatomic root

New cards
4

Enamel in decalcified section

Lost because enamel is 96% mineral Enamel is called Enamel space in decalcified sections

New cards
5

what structures are not seen in ground sections

Soft tissue (pulp, PDL, gingiva)

New cards
6

where are enamel and dentin bound

dentino-enamel junction

New cards
7

shape of DEJ

scalloped (convex towards dentin)

New cards
8

Why is the DEJ scalloped?

To provide more surface area for enamel-dentin adhesion = firm attachment

New cards
9

junction between root and dentin

dentino-cemental junction (less distinct & smooth)

New cards
10

where could DCJ be scalloped?

deciduous teeth

New cards
11

Dentin-pulp complex

Have same embryonic origin (dental papilla) and integrated histologically & functionally

Dentin is the calcified product of pulp Pulp provides vitality to dentin

New cards
12

General characteristics of dentin

Sensitive (pain) Unique to teeth Cellular (odontoblastic processes) Avascular Dynamic (ion exchange w/ environment = demineralization & remineralization) Ability to repair (tertiary dentin)

New cards
13

Color of dentin

Light yellow (becomes darker w/ age)

New cards
14

how does dentin prevent fracture of brittle enamel

Dentin is elastic

New cards
15

hardness of dentin

Slightly harder than bone and cementum Less hard than enamel

New cards
16

Resistance of dentin

Less resistant (Highly prone) to attrition, abrasion & erosion compared to enamel

New cards
17

thickness of enamel vs. color of tooth

Light can readily pass through enamel and reflected by underlying dentin Thick enamel does not permit light through = whiter crown

New cards
18

where are cells of dentin

Odontoblasts are in pulp Odontoblastic processes are in dentin

New cards
19

Radiographic appearance of dentin

More radiolucent than enamel More radiopaque than pulp

New cards
20

Strengths of dentin compared to enamel

-Less compressive strength -Higher tensile strength -Higher flexural strength -More resistant to fracture

New cards
21

Compressive strengths of enamel and dentin

Enamel = 384 mpa Dentin= 297 mpa

New cards
22

Tensile strengths of enamel & dentin

Enamel = 10 mpa Dentin = 98 mpa

New cards
23

Permeability of dentin

Highly permeable Decreases with age permeable to small substances

New cards
24

permeability of dentin depends on

size & patency of dentinal tubules

New cards
25

clinical significance of high permeability of dentin

Therapeutic substances applied to exposed dentin diffuse to pulp Help remineralization of dentin

New cards
26

Chemical composition of dentin

70% Inorganic 20% Organic 10% Water

New cards
27

Inorganic content of dentin (70%)

Hydroxyapatite crystals (same shape but smaller than enamel)

C10(PO4)6(OH)2

Carbonate (high), Fluoride, Sodium, Mg

New cards
28

Organic content of dentin

90% of organic content = Collagen 10% of organic content = Non-collagenous proteins & lipids

New cards
29

collagen fibers in organic content of dentin

Type 1 Type 3 Type 4

New cards
30

what type of collagen predominates in dentin

type 1

New cards
31

Non-collagenous proteins & lipids in dentin (organic)

Dentin phosphoprotein Dentin sialoprotein Dentin matrix protein Osteonectin Osteocalcin Osteopontin Bone sialoprotein Proteoglycans

New cards
32

Function of collagen in dentin

Rigidity Type 1 acts as scaffold to accommodate minerals in fibrils

New cards
33

function of phosphoproteins in dentin

Binds to calcium Binds to collagen to initiate crystal formation

New cards
34

function of sialoproteins in dentin

Inhibits growth of peritubular dentin to prevent occlusion of dentinal tubules

New cards
35

Mutation of what protein causes dentinogenesis imperfecta

Sialophosphoproteins

New cards
36

function of growth factors in dentin

induce production of tertiary dentin

New cards
37

function of enzymes in organic content of dentin

Catalyze reactions

New cards
38

function of phospholipids in organic content on dentin

role in Mineralization

New cards
39

where are phospholipids found in dentin

pre-dentin & dentin

New cards
40

function of proteoglycans in dentin

prevent premature mineralization until collagen fibrils attain final destination

New cards
41

proteoglycans are found more in

Predentin

New cards
42

Types of dentin according to Time of formation

-Primary dentin (predentin, mantle dentin, circumpulpal dentin) -Secondary dentin

New cards
43

Types of dentin according to Dentinal tubules

-Peritubular dentin (around dentinal tubule) -Intertubular dentin (between dentinal tubules)

New cards
44

Types of dentin according to Injury

-Tertiary dentin (reparative & reactionary) -Sclerotic dentin (dentinal tubules full of mineral) -Dead tracts (dentinal tubule full of air)

New cards
45

Types of dentin according to defect in mineralization

-Interglobular or globular dentin (Hypocalcified)

New cards
46

Sclerotic dentin & dead tracts are the

opposite of each other

New cards
47

When is primary dentin formed?

During tooth development (before closure of apical foramen)

New cards
48

when does primary dentin formation end

when root formation is complete

New cards
49

Outermost layer of primary dentin

mantle dentin

New cards
50

main bulk of primary dentin

Circumpulpal dentin

New cards
51

when does secondary dentin formation start

after root formation is complete

New cards
52

secondary dentin occurs due to

continuous slow deposition of dentin

New cards
53

where is secondary dentin seen

Roof & floor of pulp chamber

New cards
54

Pulp recession

Sign of aging in pulp; decrease in size due to the formation of secondary or tertiary dentin = pulp horns recede down

In cavity preparation in elderly, less chance of pulp exposure

New cards
55

Inorganic:organic content of secondary dentin

Similar to primary dentin # of dentinal tubules is less

New cards
56

junction between primary and secondary dentin

Slight diff staining and Less regular organization of dentinal tubules

New cards
57

what is the first formed dentin

Mantle dentin Formed even before enamel

New cards
58

where does mantle dentin lie

below dentinoenamel junction

Adjacent to DEJ and DCJ

New cards
59

mantle dentin is

Outermost layer of dentin Closest to enamel

New cards
60

thickness of mantle dentin

20um

New cards
61

Korff's fibers

First formed large, distinct collagen fibers of dentin (collagen type 3)

New cards
62

type of collagen in korff's fibers

type 3 collagen

New cards
63

what is predentin

Initial, non-mineralized layer of dentin close to pulp

New cards
64

thickness of predentin

2-6 microns thick

New cards
65

Predentin becomes

dentin, and a new layer of predentin forms below it

New cards
66

content of predentin

Only collagen No mineral (phospholipids help mineralization)

New cards
67

Type of predentin depends on

time of formation / time of sectioning

New cards
68

predentin before root completion belongs to

primary dentin

New cards
69

predentin after root completion belongs to

secondary dentin

New cards
70

predentin after injury belongs to

Tertiary dentin

New cards
71

tertiary dentin is deposited at specific sites in response to

injury (caries, attrition, abrasion, cavity preparation)

New cards
72

rate of deposition of tertiary dentin is proportional to

injury

New cards
73

tertiary dentin is seen anywhere along

pulp-dentin complex

New cards
74

dentinal tubules in tertiary dentin

Irregular Cell inclusions

New cards
75

Osteodentin

Dentin that resembles bone (having cell inclusions) Formed in tertiary dentin in response to injury

New cards
76

Types of tertiary dentin

Reparative Reactionary

New cards
77

Reparative tertiary dentin

Formed by newly differentiated odontoblasts

New cards
78

Reactionary tertiary dentin

Formed by pre-existing odontoblasts

New cards
79

What is peritubular dentin?

dentin that forms walls around dentinal tubules

New cards
80

mineralization of peritubular dentin

40% more mineralized than intertubular dentin

New cards
81

collagen in peritubular dentin

less than intertubular dentin

New cards
82

location of intertubular dentin

between dentinal tubules Form main body of dentin

New cards
83

intertubular dentin forms

main body of dentin

New cards
84

intertubular dentin represents

primary secretory product of odontoblasts

New cards
85

intertubular dentin consists of

Type 1 collagen network in which apatite crystals are deposited

New cards
86

histology of dentin

¢Dentinal tubules & Odontoblastic process ¢Peritubular dentin ¢Intertubular dentin ¢Interglobular dentin ¢Incremental lines of von Ebner ¢Tomes granular layer ¢Sclerotic dentin ¢Dead tracts ¢Enamel spindles

New cards
87

# of dentinal tubules

30,000 - 70,000 /mm2

New cards
88

diameter of dentinal tubules

Near pulp: 3 um Near enamel: 1 um

Taper from pulp to be narrowest at DEJ

New cards
89

dentinal tubules extend from

pulp to DEJ and DCJ

New cards
90

shape of dentinal tubules

Curved S shape

New cards
91

why are dentinal tubules branched

form a network for nutrients diffusion

New cards
92

lateral branches of dentinal tubules are called

Canaliculi

New cards
93

diameter of canaliculi

1 um

New cards
94

canaliculi are at right angle to

main dentinal tubule

New cards
95

function of dentinal tubules

Responsible for permeability of dentin Pathway for microbial invasion of dentin

New cards
96

content of dentinal tubules

-Odontoblastic processes (microtubules & intermediate filaments) -Dentinal fluid -Thin nerve fibrils -Peritubular dentin -Inner organic lining (Lamina limitans)

New cards
97

what is lamina limitans

Plasma membrane of odontoblastic processes that is rich in GAG

New cards
98

what is the major component of dentinal tubules

odontoblastic processes

New cards
99

enamel spindles

-Extensions of odontoblastic processes into enamel crossing DEJ -Odontoblastic processes dont withdraw quick enough after stimulating pre-ameloblasts & remain stuck in enamel

New cards
100

curvatures of dentinal tubules

Primary curvature Secondary curvature

New cards

Explore top notes

note Note
studied byStudied by 9 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 9498 people
Updated ... ago
4.7 Stars(63)
note Note
studied byStudied by 8 people
Updated ... ago
5.0 Stars(2)
note Note
studied byStudied by 108 people
Updated ... ago
4.4 Stars(5)
note Note
studied byStudied by 3 people
Updated ... ago
4.0 Stars(1)
note Note
studied byStudied by 6 people
Updated ... ago
5.0 Stars(1)
note Note
studied byStudied by 12 people
Updated ... ago
4.0 Stars(2)
note Note
studied byStudied by 90 people
Updated ... ago
4.8 Stars(4)

Explore top flashcards

flashcards Flashcard35 terms
studied byStudied by 4 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard100 terms
studied byStudied by 6 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard30 terms
studied byStudied by 18 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard57 terms
studied byStudied by 427 people
Updated ... ago
5.0 Stars(2)
flashcards Flashcard163 terms
studied byStudied by 8 people
Updated ... ago
4.0 Stars(1)
flashcards Flashcard133 terms
studied byStudied by 11 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard49 terms
studied byStudied by 11 people
Updated ... ago
5.0 Stars(1)
flashcards Flashcard28 terms
studied byStudied by 2 people
Updated ... ago
5.0 Stars(1)