Exam 3 - Dentin Pulp Complex I Colombo Flashcards
(110 cards)
1
Q
Mineralized protective component of the tooth is called:
A
Enamel
2
Q
Mineralized structural component of the tooth is called:
A
Dentin
3
Q
Main cellular component of the tooth is:
A
Pulp
4
Q
Dentin composition is highly analogous to ____, but:
A
Bone; but slightly different composition and highly different anatomy
5
Q
The crown is covered by:
A
Enamel
6
Q
The root is covered by:
A
Cementum
7
Q
Dentin composition by weight
A
- inorganic material: 70%
- organic material: 20%
- water: 10%
8
Q
Dentin composition by volume
A
- inorganic material: 45%
- organic material: 33%
- water: 22%
9
Q
Inorganic material in dentin (and enamel, bone, cementum) is called:
A
Hydroxyapatite
10
Q
The water in dentin is also termed:
A
Physiological fluid
11
Q
What is the chemical formula for hydroxyapatite?
A
Ca5(PO4)3(OH)
x2 per crystal unit cell
12
Q
Hydroxyapatite is effectively a:
A
Calcium phosphate crystal
13
Q
___ can replace the OH in hydroxyapatite
A
Fluoride (creates fluorapatite)
14
Q
Besides fluoride, what other ions can replace the OH of hydroxyapatite?
A
- zinc
- magnesium
15
Q
Hydroxyapatite crystals are arranged in _____
A
Rectangular plates
16
Q
True or false: dentin is somewhat harder than bone
A
True (Knoop number 68, bone is 50)
17
Q
True or false: enamel is much harder than dentin or bone
A
True - Knoop number 343
18
Q
Why is enamel much harder than dentin?
A
Due to how the HA is arranged
19
Q
Organic material of dentin is made of:
A
- 90% collagen
- 10% Non-collagenous proteins
20
Q
Main type of collagen found in dentin
A
Collagen type 1 (also some type 3 and type 5)
21
Q
The organic material secreted by dentin creates the _____ upon which HA is laid down
A
fibrillar collagen scaffold
22
Q
Dentin specific proteins (in the organic component)
A
- Dentin matrix protein 1 (DMP-1)
- Dentin Sialophosphoprotein (DSPP)
23
Q
DSPP is further cleaved by ____ into:
A
BMP-1; DSP, DPP, DGP
24
Q
DSP is a ____ expressed in ____
A
proteoglycan; dentinal tubules
25
____ may act to prevent mineralization in tubules
DSP
26
DGP is a _____ and may have a role in ____ (unknown)
Glycoprotein; biomineralization
27
DPP binds ____ to initiate HA formation and is attached to ____
Lots of Ca2+; collagen
28
DPP is attached to ____
Collagen
29
____ is not thought to be glycosylated
DPP
30
____ is located on the N terminus of the DSPP protein
DSP
31
____ is located on the C terminus of the DSPP protein
DPP
32
Defects in DSPP can cause:
Dentinogenesis imperfecta Types II and III
33
Type 1 Dentinogenesis results from:
Osteogenesis imperfecta (defect in type 1 collagen)
34
Both type 1 and type 2 dentinogenesis imperfecta cause:
Pulp chambers to be filled with abnormal dentin
35
True or false: Type II Dentinogenesis imperfecta is associated with osteogenesis imperfecta
False (Type 1 can result from OI)
36
Type III Dentinogenesis imperfecta is associated with:
- Enlarged pulp chambers
- hypo-mineralization
37
Type III dentinogenesis imperfecta is caused possibly due to:
Failure of DSPP expression
38
Dentin is synthesized by _____
Odontoblasts
39
What lines the pulp chamber?
Odontoblasts
40
Odontoblasts are ____ cells which extend _____ into the dentin through tubules
Polarized; cellular projections
41
The dentin-pulp complex arises from:
Dental papilla
42
Initial differentiation of dentin formation occurs after:
Critical interaction with the inner enamel epithelium
43
When odontoblasts first differentiate, they fill the ___ zone between the ____ and ____
Acellular; IEE and dental papilla
44
Vascular support arises from:
Dental papilla
45
Signal for ameloblasts to form enamel
Predentin formation
(dentin always formed before enamel!)
46
DEJ
Dentin-enamel junction; interface between the enamel and dentin where they are in **direct apposition**
47
The edge of the DEJ is:
Scalloped
48
The shape of the DEJ is important for:
- defining the **shape of the crown**
- keeping dentin directly attached to enamel during loading, **preventing shearing**
49
The DEJ is bound together by a merging of _____
enamel HA and dentin HA crystals in ridges
50
First layer of dentin formed is called ____ closest to the DEJ
Mantle dentin
51
What are von Korff's fibers
Collagen III fibers associated with fibronectin during dentin formation
52
Von Korff's fibers extend toward the _____ and branch into the ___ of the developing matrix to form the DEJ with a ____
IEE; ground substance; scalloped edge
53
Developing odontoblasts extend processes called ____ into the developing matrix which is a ____ system and secreting dentin matrix components in ____
Tome's fibers; tubule; matrix vesicles
54
Penetration of the IEE by odontoblast projections form:
Enamel spindles
55
Odontoblasts produce matrix moving away or toward the DEJ?
Away from the DEJ
56
Tomes' fiber will eventually become:
Odontoblast process
57
Dentin starts as:
Non-mineralized organic matrix (predentin)
58
Odontoblasts: Mineralization starts within ____ and deposited along the ____
secreted matrix vesicles; future DEJ
59
What happens to matrix vesicles secreted by odontoblasts?
They rupture and released mineralized matrix crystals to form non-tubular mantle dentin
60
Tubular primary dentin is formed after the formation of ____ and is regulated by ______
Mantle dentin; non-collagenous matrix proteins
61
After the DEJ is formed, ____ dentin formation begins
Circumpulpal (dentin surrounding the pulp chamber)
62
What initiates root odontoblast formation?
HERS
63
HERS eventually breaks into:
Cell Rests of Malassez
64
True or false: root dentin formation is very similar to coronal dentin formation
True
65
True or false: there is no mingling of dentin collagen with cementum collagen
False - there is some
66
Primary dentin
- First dentin formed during development
- comprises the mantle dentin and initial deposition of circumpulpal dentin
67
____ dentin is produced throughout life
Secondary
68
Secondary dentin is continuous with:
Primary dentin
| but histologically distinct
69
Coronal dentin tubules have a ___ curve; root dentin tubules are ____
Sigmoidal; straighter
70
There is greater secondary dentin deposition in around ____ which causes pulpal ____
Roof and floor; recession
71
Predentin is _____ distinct
Histologically (not yet mineralized)
72
Tertiary dentin is produced in response to:
Insult
73
Tertiary dentin can have ____ but often does not. If they are present, they are often ____ and can include ____
Tubules; disordered; cells
74
Tertiary dentin function
- acts to seal off dentinal tubules
- form bridges between dentin and resorations or in response to trauma
75
Tertiary dentin can be either ____ or ____
- reactionary
- reparative
76
In reactionary tertiary dentin formation, does trama damage odontoblasts?
No
77
Reparative dentin is ____ to odontoblasts; however, it involves recruitment and differentiation of ____ to form new ____
Damaging; mesenchymal cells; odontoblasts
78
During reparative dentin formation, there is more ___ and less ____
More BSP and OP
Less DSP and DMP-1
79
Mantle dentin
First dentin formed at the DEJ
80
Predentin
Unmineralized dentin matrix (proteins)
81
Circumpulpal dentin
dentin formed around the pulp after the mantle dentin before roots fully formed
82
Secondary dentin
dentin formed subsequent to root formation; forms throughout the life of a tooth
83
Primary feature of dentin macrostructure
Tubules
84
3 main structures in dentin
- dentin tubules with OD process
- Peritubular dentin
- intertubular dentin
85
Dentinal tubules run from ____ to ___
DEJ; OD layer of the pulp
86
Dentinal tubules are filled with
Fluid
87
Tubule density is high or low?
Very high; 59K-76K/mm2 in apposition to the pulp (half of that at the DEJ)
88
Dentinal tubules are surround by collars of:
Highly calcified peritubular dentin
89
Dentinal tubules are separated by:
Intertubular dentin (collagen I fibrils arranged perpendicular to tubules)
90
____ provide mechanical support to the enamel during loading
dentinal tubules
91
Dead tracts
have an end sealed off but otherwise empty, appear black in ground sections
92
Sclerotic dentin occurs when:
Tubules are totally filled, has a glassy translucent appearance in ground sections
93
As peritubular dentin is deposited, ____ naturally occur
Dead tracts/sclerotic dentin
starts apically, continues toward the crown with age
94
Interglobular dentin
- areas of hypomineralized dentin
- formed when fusion of mineral contain vesicles fails
95
____ can be associated with vitamin D deficiency or fluoride exposure during initial dentin formation
Interglobular dentin
96
Interglobular dentin is more common near
Mantle dentin
97
Is matrix present in interglobular dentin?
Yes
98
True or false: enamel spindles are the same as enamel
False - may have trace amounts of dentin (collagen)
99
Where do enamel spindles usually appear?
cusp tips/incisal edges
100
Cyclical deposition of primary dentin forms ____ which can be seen at 20 micron increments
Lines of von ebner
101
___ is asymmetrically deposited and more slowly
Secondary dentin
102
Contour lines of owen is equivalent to
Striae of Retzius
103
____ dentin contains the granular layer of tomes
Root
104
Granular layer of tomes becomes more granular towards:
Apical end
105
Granular layer of tomes possible forms due to:
- hypomineralized areas of dentin (similar to interglobular dentin)
- part of looped dentinal tubules found in the root sections, artifact of sectioning
- specialized dentin structures which form part of dentin/cementum junction
106
Hyaline layer of hope-well smith
dentin next to cementodentinal junction
107
Last part of root dentin which mineralizes
Hyaline layer of hopewell smith
108
Hyaline layer of hopewell smith provides attachment point for
Periodontal ligament fibers
109
What is external to the granular layer of tomes?
Hyaline layer of hopewell smith
110
Hyaline layer of hopewell smith contains:
mingled enamel matrix proteins with dentin matrix proteins
