Exam 2 - Dentin & Dentinogenesis Flashcards
1
Q
Dentin is ____ mineralized than enamel.
A
LESS
2
Q
Dentin is __% mineral/inorganic and __% organic, with __% water.
A
70; 20; 10
3
Q
What type of collagen does dentin contain?
A
Type I, with trace Type III & V
4
Q
50% of non-collagenous proteins in dentin are ____.
A
phosphoproteins
5
Q
What non-collagenous proteins are present in dentin?
A
sialoprotein sialophosphoprotein proteoglycans glycosaminoglycans osteonectin osteopontin
6
Q
Is Type I collagen in dentin the same as Type I in bone?
A
NO
7
Q
T/F: Type I collagen in dentin has lower ratios of proline and hydroxyproline than Type I collagen in bone.
A
FALSE; dentin has higher ratios of proline and hydroxyproline than bone
8
Q
T/F: Type I collagen in dentin has a higher prevalence of cross-linking than Type I collagen in bone.
A
TRUE
9
Q
Does Type I collagen in dentin have a higher level of bound water than Type I collagen in bone?
A
YES
10
Q
T/F: Hydroxyapatite crystals in dentin are highly organized, much like enamel.
A
FALSE; hydroxyapatite crystals in dentin are NOT organized like HA crystals in enamel - they are randomly oriented
11
Q
Biglycan and Decorin are ____ non-collagenous proteins in dentin.
A
proteoglycans
12
Q
Chondroitin-4-sulfate and chondroitin-6-sulfate are ____ non-collagenous proteins in dentin.
A
glycosaminoglycans
13
Q
Gla-proteins, osteonectin, and osteopontin are all ___ matrix non-collagenous proteins.
A
dentin
14
Q
____ contains the receptor-binding sequence “arginine-glycine-asparagine,” or the RGD binding complex.
A
Osteopontin
15
Q
____ are gelatinous, undergo mineralization, and are necessary for initiation, mineralization and controlling the size of crystalline structures.
A
Matrix proteins
16
Q
What are the 4 life cycle stages of odontoblasts?
A
1) Pre-odontoblast
2) Secretory odontoblast
3) Transitional odontoblast
4) Resting odontoblast
17
Q
Where is the stimulus for ectomesenchymal cell differentiation into pre-odontoblasts derived from?
A
fibronectin (and some GF from the IEE)
18
Q
Where is fibronectin found?
A
the basal lamina of the IEE
19
Q
What substance must be present for ectomesenchymal cells to differentiate into pre-odontoblasts?
A
fibronectin
20
Q
Pre-odontoblastic ____ receptors allow the cells to align themselves along the basal lamina, assume polarity, and differentiate into secretory cells.
A
fibronectin
21
Q
Which life cycle stage of odontoblasts are the “functional odontoblasts?”
A
secretory odontoblasts
22
Q
Secretory odontoblasts are ___ cells with extensive junctional complexes and gap junctions.
A
tall columnar
23
Q
____ exhibit significant alkaline phosphatase activity which helps with mineralization of hydroxyapatite.
A
Secretory odontoblasts
24
Q
What is the role of alkaline phosphatase?
A
mineralizes hydroxyapatite crystals
25
Secretory odontoblasts secrete type ___ collagen, and trace amounts of types __ and __.
I; III; V
26
What do secretory odontoblasts use for their mechanism of secretion?
secrete matrix vesicles
27
T/F: Odontoblasts make their own alkaline phosphatase and ameloblasts do not.
TRUE
28
What matrix vesicles do secretory odontoblasts secrete?
```
phospholipids
alkaline phosphatase
phosphoproteins
pyrophosphatase
Ca2+ and PO4-
Annexin
HA crystal crystallites
```
29
____ mediates the flow of calcium into the matrix vesicle and also serves as a collagen receptor that binds matrix vesicles to collagen.
Annexin
30
What is the role of annexin in dentin?
- mediates calcium flow into matrix vesicle
| - serves as a collagen receptor that binds matrix vesicles to collagen
31
Which odontoblasts in the life cycle start to slow down and develop autophagic vacuoles?
transitional odontoblasts
32
____ are flat and have no ER or Golgi bodies present.
resting odontoblasts
33
What growth factors are secreted by the IEE?
transforming growth factor (TGF)
bone morphogenic proteins (BMP)
insulin-like growth factor (IGF)
fibroblast growth factor (FGF)
34
T/F: Complete differentiation requires a set number of cell divisions which allows cells to express appropriate receptors able to bind to growth factors.
TRUE
35
What does the last mitotic division of an odontoblast result in?
a mature odontoblast and a daughter cell that is forced into the sub-odontoblastic layer
36
The _____ layer has fully differentiated cells and lie right against the basement membrane.
dentin-forming
37
The ____ layer has cells that are blocked from the inductive influences of growth factors and are not fully differeniated.
subodontoblastic
38
Can cells of the subodontoblastic layer form dentin?
NO
39
What are the cells of the subodontoblastic layer limited to forming?
reparative odontoblasts
40
What is the 1st formed dentin?
mantle dentin
41
Mantle dentin is formed by ____ odontoblasts.
secretory
42
Mantle dentin matrix is composed of Type __ and __ collagen.
I; III
43
Collagen fibers are arranged ____ to the basal lamina of the IEE.
perpendicular
44
What does mantle dentin stimulate?
stimulates ameloblasts to secrete enamel
45
Organic dentinal matrix is deposited incrementally at a rate of __ to __ um per 24 hours.
4; 8
46
What are the incremental lines of dentin called?
lines of von Ebner
47
____ are incremental lines in dentin that represent the hesitations in matrix formation.
lines of von Ebner
48
Are lines of von Ebner hyper- or hypomineralized?
HYPOmineralized
49
When do these areas of hypomineralization (lines of von Ebner) occur?
every 4-20 days of matrix deposition
50
Deficiencies and irregularities in dentinogenesis, resulting in areas of hypomineralization appear as what structures?
neonatal line
lines of Owen
areas of interglobular dentin
51
Exaggerated lines of von Ebner that occur during periods of altered cell metabolism may manifest as:
neonatal line - trauma from childbirth
| lines of Owen - exaggerated lines from longer hesitation
52
____ arise from trauma from childbirth.
Neonatal lines
53
____ are exaggerated lines of von Ebner due to longer hesitation.
Lines of Owen
54
Which teeth are neonatal lines found in?
all primary teeth
| 1st permanent molars
55
The Type I collagen matrix has fibers that run ___ to the basal lamina.
parallel
56
Where are the diameter and density of dentin tubules greatest near?
the pulpal surface
57
Where are the diameter and density of dentin tubules the smallest?
near the DEJ
58
Because of the decreasing ____ of the pulp chamber, the number of dentinal tubules per unit area at the pulpal surface is greater than at the DEJ (which is 1/2 of those at pulp).
volume
59
Can odontoblastic processes branch?
YES - they branch as they exit DEJ
60
Why do odontoblastic processes branch?
to allow the processes to have anchor points so it can grow and stretch without pulling away/separating
61
____ dentin is more mineralized; ____ dentin is demineralized.
Peritubular; intertubular
62
_____ dentin is around the tubule, is more mineralized, and is more resistant to etch ("white rings").
Peritubular
63
____ dentin is located between tubules and is more "hairy."
Intertubular
64
____ dentin is mineralized in an organized fashion.
Linear
65
_____ dentin is characterized by interglobular spaces that are unmineralized or hypomineralized dentin between islands of normal calcified dentinal layers.
Globular (interglobular)
66
Where is globular/interglobular dentin formed?
in the crowns of teeth between normal calcified dentinal layers
67
Where specifically is globular dentin mostly found?
in the crowns of teeth and in Tome's granular layer
68
____ is a granular-appearing layer in the dentin of the root adjacent to the cementum, possibly comprised of hypomineralized interglobular dentin.
Tome's Granular Layer
69
Is mantle dentin primary dentin?
NO
70
____ is all dentin (except mantle dentin) that is formed up until the time the tooth achieves functional occlusion.
Primary dentin
71
____ is all dentin that is formed after the tooth achieves functional occlusion.
Secondary dentin
72
What are dentin tubules called that are void of odontoblastic processes?
dead tracts
73
What are dead tracts filled with and what do they look like?
filled with air or organic debris
| looks black in transmitted light microscopy
74
What is dentin called that is occluded with mineral?
sclerotic dentin
75
What is sclerotic dentin and what does it look like?
occluded with mineral
non-tubular and nearly transparent
looks black in transmitted light microscopy
76
Does the presence of sclerotic dentin increase or decrease with age?
INCREASE
77
What is dentin called that's deposited by newly differentiated odontoblasts at the site of pulpal trauma?
reparative dentin (tertiary dentin)
78
What stimulates and forms the matrix of reparative dentin?
cells in the subodonoblastic layer, once exposed to growth factors
79
Is all tertiary dentin formation the result of caries?
NO - pulp capping initiates reparative dentin formation too
80
What is pulp capping?
stimulating a bridge of reparative dentin by using calcium hydroxide to seal off exposed pulp
81
Cells in the subodontoblastic layer, once exposed to growth factors released by stimulated ____, differentiate and form the matrix of reparative dentin.
pulpal cells
82
What part of the tooth does tetracycline affect?
the part of the tooth that was developing at the time the drug was introduced
83
T/F: Staining from tetracycline only affects the top layer of the tooth.
FALSE - tetracycline staining gets deeper as you cut into the tooth
84
How is tetracycline staining treated?
bleaching (6-7 months) or veneers
85
T/F: Both dentin and enamel are affected in dentinogenesis imperfecta.
FALSE - dentin is affected and enamel is NORMAL
86
What hereditary defect results in normal enamel that chips off easily due to lack of support by abnormal underlying dentin?
dentinogenesis imperfecta
87
In dentinogenesis, there is a lack of ____ at the DEJ.
tuftelin
88
What hereditary defect results in bluish-gray teeth with an opalescent sheen and obliterated pulp chambers?
dentinogenesis imperfecta
89
____ is a loss of tooth structure due to mechanical wear due to bruxism (tooth to tooth contact during mastication or parafunction).
Attrition
90
____ results in matching wear facets on occluding surfaces and shiny facets on amalgam contacts.
Attrition
91
T/F: Enamel and dentin wear at the same rate.
TRUE
92
How can the pulp chamber be exposed in attrition, but not cause debilitating pain?
reparative dentin is laid down on top to protect the pulp
93
____ is the loss of hard dental tissue by chemical processes.
Erosion
94
____ results in broad concavities, with cupping of occlusal surfaces and dentin exposure.
Erosion
95
Do you see wear on non-occluding surfaces with erosion?
YES - and incisal translucency
96
Are patients with erosion hypersensitive?
YES
97
How would you treat caries that is only present in the enamel?
with fluoride
98
How would you treat caries that goes deeper into the enamel?
with a sealant
99
How would you treat caries that has entered the dentin?
restore
100
How would you treat caries that has entered the pulp?
extraction or root canal
101
Caries is a balance between ____ and ____ factors.
pathological; protective
102
Acid-producing bacteria, frequent snacking on fermentable carbohydrates, and subnormal saliva flow are all ____ factors.
pathological
103
Proper saliva flow and its components, fluoride/calcium/phosphate, and chlorhexidine/iodine/xylitol are all ____ factors.
protective
104
Hydroxyapatite crystals exhibit a core of more soluble _____.
carbonate apatite
105
Where does carbonate substitution in the lattice structure of enamel primarily occur?
phosphate sites
106
What portion of hydroxyapatite crystals are eroded preferentially?
core of carbonated apatite
107
Which element substitutes hydroxyl ions in hydroxyapatite crystals, conferring greater stability and resistance to acidic dissolution?
fluoride
108
What are the bacteria responsible for dental caries on dentin and enamel surfaces?
Streptococcus mutans
Streptococcus sorbrinus
Streptococcus gordonii
Lactobacillus acidophilus
109
What bacteria are responsible for dental caries on roots?
Actinomyces viscosus
| Candida albicans
110
Caries spread ____ as it reaches the DEJ and progresses into the dentin.
laterally
111
Why does the caries process spread laterally at the DEJ?
the spread is due to the branching of dentinal tubules (odontoblastic processes) at the DEJ
112
What do caries look like in the enamel? In the dentin? What is the shape?
initial caries lesion exhibits small opening in enamel
| then, a pyramidal shaped lesion within the dentin with the apex of the pyramid pointing towards the pulp
113
What actually causes the substantial cavitation of advanced caries?
the bulk of the decay is beneath the enamel surface, so when caries invades the dentin, there is not enough dentin underneath to support the enamel (so then it chips)
114
What is the cause of a periapical abscess?
caries that has progressed into the pulp cavity, where pus forms and causes necrosis in the PDL and alveolar bone
115
How can grooves in teeth be protected from caries?
sealants
116
How many adults suffer from dentinal sensitivity?
1 in 5 adults
117
What teeth are most commonly affected by sensitivity issues?
canines and premolars
118
What are some stimuli for sensitivity?
```
cold or hot beverages
sweet, sour, or acidic foods
overly aggressive brushing
acidogenic plaque bacteria
cosmetic tooth bleaching
clenching and bruxism
```
119
What theory of dentinal sensitivity theorizes that sensitivity is caused by direct stimulation of nerve endings in tubules?
Direct Innervation Theory (not actually supported though because free nerve endings don't extend into DEJ)
120
What theory of dentinal sensitivity theorizes that sensitivity is caused by stimulation of odontoblasts that are coupled to nerves in pulp?
Transduction Theory
121
What theory of dentinal sensitivity theorizes that sensitivity is caused by movement of tissue fluids within dentinal tubules that stimulate free nerve endings in close association with dentin?
Hydrodynamic Theory (most accepted theory)
122
_____ Law states that the volume of a gas or fluid is directly proportional to the amount of heat applied at a constant pressure.
Charles'
123
Heat to a sensitive tooth = fluid movement volume ____; Cold to a sensitive tooth = fluid movement volume ____.
increased; decreased
