QUIZ 3 Dentin Pulp Complex I Flashcards
1
Q
dentin is the main ___ material of the tooth
A
structural
2
Q
the structure of the dentin is directly linked to what?
A
its primary function of supporting tooth loading
3
Q
briefly describe enamel, dentin, and pulp
A
- enamel
- mineralized protective component
- dentin
- mineralized structural component
- pulp
- main cellular component
4
Q
dentin is highly analogous to ___, but slightly different composition and highly different anatomy
A
bone
5
Q
the crown is covered by ___, and the root is covered by ___
A
- enamel
- cementum
6
Q
dentin is ___% inorganic material, ___% organic material, and ___% water
A
70%, 20%, 10%
7
Q
hydroxyapatite makes up the ___ component of dentin
A
inorganic material
8
Q
what is the formula for hydroxyapatite, and how many molecules of HA are in each crystal unit cell?
A
Ca5(PO4)3(OH)
2 per crystal unit cell
9
Q
HA is effectively a ___ ___ crystal
A
calcium phosphate
10
Q
fluoride can replace the ___ in hydroxyapatite, creating ___
A
- OH
- fluoroapatite
11
Q
besides fluoride, what else can replace the OH in hydroxyapatite in dentin?
A
zinc, magnesium, and others
12
Q
in dentin, HA crystals are what shape?
A
flattened rectangular plates
13
Q
what are the dimensions of HA in dentin?
A
- 60-70 nm long
- 20-30 nm wide
- 3-4 nm thick
14
Q
dentin is somewhat harder than ___. what are the knoop numbers for dentin, enamel, and bone?
A
- bone
- knoop numbers:
- dentin - 68
- enamel - 343
- cortical bone - 50
15
Q
what is the composition of the organic material component of dentin?
A
- 90% collagen
- mostly I, some III and V
- 10% non-collagenous proteins
16
Q
describe the collagen component of the organic component of dentin
A
- 90%
- mostly collagen I, some III and V
- fibrillar collagen scaffold upon which HA crystals are laid down
17
Q
what are the 5 non-collagenous proteins that dentin has in common with bone?
A
- bone sialoprotein (BSP)
- osteopontin (OP)
- osteocalcin (OC)
- osteonectin (ON)
- matrix extracellular phosphoglycoprotein
18
Q
what are the 2 main dentin specific non-collagenous proteins?
A
- dentin matrix protein-1 (DMP-1)
- dentin sialophosphoprotein (DSPP)
- *still found in bone, but only trace amounts
19
Q
DSPP can be further cleaved into what 3 functional proteins?
A
- dentin sialoprotein (DSP)
- dentin phosphoprotein (DPP)
- dentin glycoprotein (DG)
20
Q
DSPP is cleaved rapidly by what enzyme?
A
BMP-1
21
Q
describe DSP
A
- proteoglycan
- expressed in dentinal tubules
- may act to prevent mineralization
- similar to DMP-1
22
Q
describe DGP
A
- glycoprotein
- role in biomineralization?
- unknown function
23
Q
describe DPP
A
- binds lots of calcium, initiates HA formation
- attached to collagen
- not thought to be glycosylated
24
Q
DSP comes from which end of DSPP?
A
N terminus
25
DPP comes from which end of DSPP?
C terminus
26
defects in DSPP can cause what?
dentinogenesis imperfecta types II and III
27
which dentinogenesis imperfecta type is described by the following:
results from OI (defect in collagen I), pulp chambers filled with abnormal dentin
type I (not a result of defects in DSPP)
28
which dentinogenesis imperfecta type is describe by the following?
not associated with osteogenesis imperfecta (DSPP defect), pulp chambers filled with abnormal dentin
type II
29
which dentinogenesis imperfecta type is describe by the following?
enlarged pulp chambers, hypo-mineralization, possibly failure of DSPP expression
type III
30
dentin is synthesized by \_\_\_, which line the pulp chamber
odontoblasts
31
odontoblasts have a ___ origin
mesenchymal
32
odontoblasts are ___ cells which extend cellular projections into the dentin through \_\_\_
* polarized
* tubules
33
label this photo
34
the dentin-pulp complex arises from \_\_\_
dental papilla
35
in the development of dentin, odontoblasts differentiate and fill what?
the acellular zone between the IEE and dental papilla
36
is there vascular support for odontoblasts?
yes
37
in the development of dentin, initial differentiation involves the critical interaction with the \_\_\_
IEE
38
the ___ is the interface betwen the enamel and dentin, where they are in direct apposition
DEJ
39
the DEJ has a ___ edge
scalloped
40
why is the shape (scalloped) of the DEJ critical?
* defines the shape of the crown
* keeps dentin directly attached to enamel during loading (no shearing)
41
the DEJ is bound by a merging together of ___ and ___ in ridges, which are most pronounced under the \_\_\_
* enamel HA crystals
* dentin HA crystals
* crown
42
why is dentin/enamel shearing bad?
the structure of the tooth can break down and compromise the structural stability of the tooth
43
which is the first layer of dentin formed?
mantle dentin, closts to the DEJ
44
are there tubules in mantle dentin?
no
45
what are von korff's fibers?
* 0.1-0.2 mm collage III fibers
* associated with fibronectin
* laid down by odontoblasts during dentin formation
46
von korff's fibers extend towards the ___ and branch into the ground substance of the developing matrix, forming the \_\_\_
* IEE
* DEJ (with scalloped edge)
47
after von korff's fibers form the DEJ, developing odontoblasts begin extending processes (\_\_\_) into the developing matrix (\_\_\_), and secreting dentin matrix components in \_\_\_
* tomes' fibers
* tubule system
* matrix vesicles
48
odontoblasts produce matrix, and move away from the \_\_\_
DEJ
49
when odontoblasts move away from the DEJ, they leave behind \_\_\_, which is the future odontoblast process
tomes' fiber (not tomes' process)
50
dentin starts as ___ organic matrix
non-mineralized (aka predentin)
51
mineralization of predentin starts within \_\_\_, deposited along the future DEJ
OD secreted matrix vesicles
52
how is non-tubular mantle dentin formed?
secreted matrix vesicles rupture and release mineralized matrix crystals
53
how is tubular primary dentin formed?
formed after non-tubular mantle dentin
non-collagenous matrix proteins regulate subsequent dentin formation
54
after DEJ formation, ___ dentin formation begins
circumpulpal
55
in the formation of root dentin, ___ initiates odontoblast differentiation
hertwig's epithelial root sheath (HERS)
56
after initiating odontoblast differentiation, HERS will eventually break into \_\_\_
cell rests of malassez
57
root dentin formation is very similar to \_\_\_
coronal dentin formation
58
what are the possible differences between coronal dentin formation and root dentin formation?
* anatomical
* some mingling of dentin collagen with cementum collagen
59
\_\_\_ is the first dentin formed during development.
primary dentin
all the dentin made before the roots are formed
60
primary dentin is comprised of ___ and \_\_\_
the mantle dentin and the initial deposition of circumpulpal dentin
61
\_\_\_ is tubular dentin laid down subsequent to root formation
secondary dentin
62
\_\_\_ dentin is produced throughout life
secondary
63
secondary dentin is continuous with primary dentin, but is ___ distinct
histologically
64
coronal dentin tubules have a ___ curve, and root dentin tubules are \_\_\_
* sigmoidal (due to odontoblast crowding)
* much straighter
65
there is greater secondary dentin deposition around where?
roof and floor (top and bottom of pulp chamber) - pulpal recession
66
why is pre-dentin so easy to distinguish from other types of dentin histologically?
because it is the only type of dentin that is not mineralized
67
\_\_\_ is dentin produced in response to insult
tertiary dentin
68
\_\_\_ can have tubules, but often does not. if tubules are present, they are often \_\_\_
* tertiary dentin
* disordered
69
tertiary dentin acts to seal off \_\_\_, or to form bridges between ___ and ___ or in response to \_\_\_
* dentinal tubules
* dentin
* restorations
* trauma
70
what is the difference between reactionary and reparative tertiary dentin?
* reactionary - trauma does not damage odontoblasts (mild stimulus)
* reparative - trauma damages odontoblasts, involves recruitment and differentiation of mesenchymal cells, forming new odontoblasts (strong stimulus)
71
tertiary dentin has less ___ and \_\_\_, and more ___ and \_\_\_
* DSP and DMP-1
* BSP and OP
72
what is the primary feature of dentin macrostructure?
tubules
73
what are the 3 main structures in dentin?
* dentin tubules (with OD processes)
* peritubular dentin (surrounds dentin tubules)
* intertubular dentin (in between peritubular dentin)
74
dentinal tubules run from the ___ to the \_\_\_
DEJ to the OD layer of the pulp
75
do dentinal tubules have fluid?
yes, they are fluid-filled
76
describe tubule density in apposition to the pulp vs DEJ
* density is high in apposition to the pulp
* 59K - 76K/mm2
* around half at the DEJ
77
dentinal tubules are surrounded by collars of \_\_\_
highly calcified peritubular dentin
78
the dentinal tubules/ peritubular complexes are separated by \_\_\_
intertubular dentin, which is 50-200nm collagen I fibrils arranged perpendicular to tubules
79
dentinal tubules can form \_\_\_, especially in the root
secondary branches
80
dentinal tubules provide ___ to the enamel during loading
mechanical support
81
after breaking through the \_\_\_, bacteria can move rapidly through the dentinal tubules
DEJ
82
what happens to the matrix and protein scaffold when bacteria is introduced to dentin?
mineralized matrix is liquefied and protein scaffold is eroded
83
what is the response to bacterial infiltration in the dentin?
formation of tertiary dentin to occlude tubules
84
what are dead tracts?
seen in ground sections, they are trapped air in empty tubules - seald off after odontoblast death (insult or apoptosis)
histologically, they look black
85
\_\_\_ is a collective term for tubules that have become occluded
sclerotic dentin
86
sclerotic dentin has a \_\_\_, ___ appearance in ground sections
glassy, translucent
87
what is sclerotic dentin a result of?
* occurs naturally, with age as peritubular dentin is deposited
1. can occur by mineral deposition only
2. diffuse mineralization around a living OD process
3. or mineralization of the cellular process and the collagen fibers along the inside of the tubule
88
sclerotic dentin starts \_\_\_, then continues towards the ___ with age
* apically
* crown
89
\_\_\_ are ares of hypomineralized dentin
interglobular dentin
90
interglobular dentin is formed by the failure of the fusion of \_\_\_
mineral containing vesicles
91
interglobular dentin can be associated with ___ deficiency or ___ exposure during initial dentin formation
* vitamin D deficiency
* fluoride exposure
92
interglobular dentin is more common near ___ dentin
mantle dentin
93
T or F:
tubules never run through areas of interglobular dentin
false
tubules often run through areas of interglobular dentin, where matrix is present
94
dentin matrix is deposited continually at what rate?
4 micrometers/day
95
every 5 days or so, there is a layer of primary dentin deposited which as a noticeably different orientation of \_\_\_
collagen fibers
96
the different orientation of collagen fibers from the layer of primary dentin deposited every 5 days forms the \_\_\_, which can be seen around 20 micrometer intervals
lines of von ebner
97
mineralization of primary dentin occurs at around what rate?
2 micrometers every 12 hours
98
secondary dentin is ___ deposited, which is slower or faster than primary dentin deposition?
* asymmetrically
* slower
99
what are contour lines of owen?
* enhanced lines in dentin that indicate disruption of tooth formation (ie. neonatal line)
* equivalent to the striae of retzius in the enamel (where there is also a neonatal line)
100
what is the granular layer of tomes?
dots around the root dentin of ground sections
101
the granular layer of tomes gets more granular toward the ___ end
apical
102
describe possibilities of what granular layer of tomes is caused by
* hypomineralized areas of the dentin, similar to interglobular dentin
* part of looped dentinal tubules found in the root sections, an artifact of sectioning
* specialized dentin structures which form part of the dentin-cementum junction
