NBDE ANATOMICAL SCIENCES: Tooth Components Flashcards
(293 cards)
1
Q
A 17 year old man falls down and chips the incisal edge of his maxillary central incisor, reducing the length of the crown. The dentist informs him that the tooth may erupt a little to compensate for the loss. Which structure will be deposited in the apex of the tooth when the tooth continues to erupt?
A
cementum
2
Q
the bone-like mineralized tissue in our oral cavity is
A
cementum
3
Q
the primary function of cementum is to
A
attach Sharpey’s fibers
4
Q
compared to dentin, cementum is:
- softer or harder than dentin
- is it softer or harder than bone?
- color is lighter or darker than dentin
A
- it is softer than dentin (because it is less calcified than dentin)
- it is harder than bone
- it is lighter yellow than dentin
5
Q
cementum is formed by ___ of the ___
A
cementoblasts from the PDL
6
Q
Dentin is formed by ___ of the ___
A
odontoblasts of the pulp
7
Q
cementum develops from the dental ___
A
follicle aka dental sac
8
Q
does cementum more closely resemble bone or dentin?
A
Bone
9
Q
unlike bone, cementum does not have _ or _.
A
no haversian system or blood vessels. it is avascular
10
Q
- is bone vascular
2. is cementum vascular
A
- bone is vascular
2. cementum is avascular
11
Q
mature cementum is by composition:
- __% mineralized inorganic material (hydroxyapatite)
- __% organic material
A
- 45-50% mineralized inorganic material
2. 50% organic material = mostly collagen and noncollagenous matrix protein
12
Q
the organic portion of cementum is primarily composed of
A
collagen and proteins
13
Q
does cementum have any nerve innervation or vascularity?
A
neither
14
Q
cementum is thickest where in the root
A
at the apex, thinnest at the CEJ at cervix of the tooth
15
Q
cementum/dentin/enamel is important in orthodontics
A
cementum
16
Q
cementum is more resistant to __ than alveolar bone, permitting orthodontic movement of teeth without root resoption.
A
resorption
17
Q
there are two types of cementum that are functionally different. T/F
A
False! there are two types of cementum that functionally are NO DIFFERENT
18
Q
Acellular cementum is aka
A
primary cementum
19
Q
cellular cementum is aka
A
secondary cementum
20
Q
the first layers of cementum deposited at the DCJ and contains no embedded cementocytes is which kind of cementum
A
acellular (think no cells)
21
Q
the last layers of cementum deposited over the acellular cementum
A
cellular
22
Q
- cellular cementum is located in the _ third of the root
2. acellular is located _
A
- cellular is in apical third
- acellular is in the coronal 2/3 of the root.
makes sense bc tooth forms from cusp towards root. and remember near the root you will have more cells.
23
Q
which forms at a faster rate - acellular or cellular
A
cellular
to remember think of the size of root it is smaller in the bottom so less area to cover
24
Q
why is cellular cementum the thickest
A
to compensate for occlusal/insical wear and passive eruption of the tooth
25
composition of bone is _% inorganic, _% organic, _% water
50% inorganic, 25% collagen, 25% water
26
intertubular dentin is formed in peripheral parts of the mineralized dentin inside the walls of dentin tubules. T/F
False
| peritubular is inside the tubules. intertubular is outside
27
T/F Peritubular dentin is highly mineralized and it also contains little collagen.
True
28
___ dentin is formed by odontoblasts thru predentin meineralization bw the tubules
intertubular
29
which dentin has a dense collagen matrix
intertubular dentin
30
1. intertubular dentin (bw tubules) has a dense collagen matrix. How about peritubular dentin?
it contains very little collagen
31
_ dentin is formed in peripheral parts of the mineralized dentin inside the walls of dentin tubules
peritubular dentin
32
the first dentin formed is
mantle dentin
33
mantle dentin is the outermost/inner most layer of primary dentin
outermost
34
is mantle dentin more/less mineralized than other layers of primary dentin (circumpulpal)
slightly less
35
name the 2 types of primary dentin
circumpulpal and mantle dentin
36
the layer of dentin around outer pulpal wall is called
circumpulpal dentin
37
is primary or secondary dentin more mineralized
primary > secondary
38
which type of dentin is formed after completion of the apical foramen?
secondary
39
which forms faster primary or secondary dentin
primary
40
primary dentin and cellular cementum form __ than secondary dentin and acellular cementum
faster
41
__ dentin outlines the pulp chamber and constitutes the main part of the dentin mass
primary
42
which dentin is formed as a result of injury
tertiary/reparative/reactionary dentin
43
tertiary/reparative/reactionary dentin has an ___pattern of tubules
irregular
44
each dentinal tubule contains the cytoplasmic cell process of an odontoblast called
Tome's fiber
45
___secrete the organic components of the dentin matrix
odontoblasts
46
odontoblasts secrete the organic components of the dentin matrix which is made of which type of collagen
type 1
47
___ are a group of empty tubules due to the death of odontoblasts whose processes formerly filled the tubules
dead tracts
48
these tracts have been attributed to the aging process of dentinal tissue
dead tracts
49
dead tracts may also be caused by
caries, erosion, cavity preparation or odontoblastic crowding
50
the cell free zone of the pulp is aka
zone of Weil
51
the innermost tissue of the tooth is: Pulp/dentin/enamel/cementum
pulp
52
1. the pulp is formed from central cells of the dental
| 2. cementum and PDL is formed from the dental
1. papilla
| 2. follicle aka dental sac
53
__ pulp is located in the pulp chamber and forms pulp horns
coronal
54
_ pulp is located in the pulp canals (root portion of tooth)
radicular
55
the apical foramen allows the pulp to communicate with the
PDL
56
accessory canals form when __ encounters a __ during root formation.
Hertwig's epithelial root sheath
| blood vessel
57
when Hertwig's epithelial root sheath encounters a blood vessel, the root structure forms around the vessel, forming the __
accessory canal
58
the peripheral aspect of dental pulp is referred to as the ___ zone. It differentiates into a layer of dentin-forming odontoblasts
odontogenic
59
immediately subjacent to the odontoblast layer is the __zone
cell-free zone (of Weil)
60
the cell free zone of Weil contains numerous bundles of
reticular fibers aka (Korff's fibers)
61
reticular fibers aka (Korff's fibers) pass from the central pulp region, across the cell-free zone and between the odontoblasts, with their distal ends incorporatied into the
dentin matrix
62
are there capillaries/nerves in the cell free zone?
yes
63
right under the cell free zone is the __ zone, containing numerous fibroblasts (the predominant cell type of pulp)
cell-rich zone
64
are odontoblasts capable of cell division
no
65
since odontoblasts are incapable of cell division, any dental procedure that relies on the ___ after destruction of odontoblasts
formation of new dentin - differentiation of new odontoblasts from these multipotential cells of the pulp
66
what cells can you find in pulp
odontoblasts, plasma cells, lymphocytes, eosinophils (POLE)
67
name the layers of the pulp
odontogenic zone (odontoblasts) = periphery, cell free zone of weil (reticular fibers, capillaries and nerves), cell-rich zone (fibroblasts)
68
medial to the cell-rich zone is the deep pulp cavity that contains
subodontoblastic plexus of Raschkow
69
All of the following are stages of amelogenesis except one:
```
presecretory
secretory
transitional
morphogenic
maturation
post-maturation
```
morphogenic
70
amelogenesis occurs during which stage in tooth development
appositional
71
enamel matrix is produced by _ cells
ameloblast
72
Ameloblasts are columnar cells that differentiate during the _ stage in the crown area
bell stage
73
the enamel matrix is secreted from each ameloblast from its ___
Tomes' process
74
Tomes' process is the secretory surface of the ameloblast that faces the
DEJ
75
Enamel matrix is firs formed in the __ portion of the future crown near the _
incisal/occlusal
| DEJ
76
___ is produced in a rhythmic fashion
enamel
77
the odontoblasts begin dentin formation (dentinogenesis) __ enamel formation by ameloblasts
immediately before
78
dentinogenesis begins with the odontoblasts layind down a dentin matrix aka ___, moving from the __ towards the__
predentin
| from DEJ toward the pulp.
79
the most recently formed dentin layer is always adjacent to the
pulpal surface
80
predentin/dentin matrix is a mesenchymal product consisting of __
non mineralized collagen fibers
81
these odontoblasts are induced by the newly formed ameloblasts to produce predentin in layers moving ___ DEJ
away from the
82
where does calcification of a tooth begin
DEJ
83
the morphology of the DEJ is determined at _ stage
bell
84
the oldest enamel in a fully erupted molar is located
at the DEJ underlying a cusp
85
in order for ameloblasts to form enamel, cells from the __ must be present
stratum intermedium
86
pulpal involvement of a carious lesion in a young child is much more likely bc
pulp chamber is larger in primary teeth compared to permanent teeth
87
dental pulp is CT so it has everything other CT does such as
tissue fluid, intercellular substance, cells, lymphatics, vascular system nerves, fibers
88
cells found in the pulp
fibroblast (most numerous), odontoblasts (only the cell bodies in the pulp), undifferentiated mesenchymal cells, lymphocytes, plasma cells and eosinophils
89
how many nerves enter anterior teeth
one
90
how many nerves enter posterior teeth (premolars and molars)
several large nerves
91
t/f a young premolar may have as many as 700 myelinated and 2000 unmyelinated axons entering the apex
true
92
the only 2 types of nerve fibers in the pulp are
afferent sensory fibers and autonomic sympathetic nerve fibers
93
are parasympathetic nerve fibers in the pulp
no
94
the sympthatetic nerve fibers that extend from neurons have their cell bodies in the _ ganglion in the skull
superior cervical ganglion
95
sympathetic nerve fibers are myelinated/unmyelinated and travel with __
unmyelinated
| BV's
96
the sympathetic nerve fibers innervate the smooth muscle cels of the arterioles and therefore regulate the
blood flow in the capillary network
97
afferent (sensory) fibers arise from the maxillary and mandibular branches of _ CN
CNV
98
Afferent Sensory fibers are predominantly myelinated/unmyelinated
myelinated
99
1. myelinated nerve fibers of the pulp are__
| 2. unmyelinated nerve fibers are
1. afferent sensory nerve fibers
| 2. sympathetic (ANS) nerve fibers
100
The afferent sensory fibers terminate in the central pulp where some will send out individual fibers that form the ___ just under the odontoblast layer
subodontoblastic plexus of Raschkow
101
in addition to being the formative organ of dentin, the pulp has what 3 other functions
nutritive - keeps the organic components of surrounding mineralized tissue supplied w/moisture and nutrients
sensory-extremes in temp, pressure, or trauma to dentin or pulp perceived as pain
protective- formation of reparative or tertiary dentin (by odontoblasts)
102
pulp capping is more successful in young teeth because:
1. apical foramen in young pulp is__
2. young pulp contains __ cells (odontoblasts)
3. young pulp is very __
4. young pulp has fewer
5. young pulp has more tissue__
6. young pulp lacks __
1. large
2. more
3. vascular
4. fibrous elements
5. fluid
6. collateral circulation
103
main function of cementum
attach sharpey's fibers
104
cementum is composed of mineralized fibrous matrix and what cells
cementocytes
105
sharpey's fibers are the terminal portions of the principal fibers of the PDL and are each inserted into the bone and outer surface of cementum at _ degrees
90
106
other functions of cementum
compensates for the loss of tooth surface due to occlusal wear by deposition of cementum throughout life
protects the root surface from resorption during vertical eruption and tooth movement
107
enamel vs cementum
1. __ has collagen fibers
2. __ has cellular components in the mature tissue
1. cementum
| 2. cementum
108
uncalcified (immature) cementum in the peripheral layer of developing cementum laid down by cementoblasts during cementogenesis
cementoid
109
when the cementoid reaches __ the cementoid surrounding the cementocytes become calcified or matured and is then considered cementum
its full thickness
110
what are cementocytes
they are cementoblasts trapped by the cemntum they produce
111
an irritating or painful response to cold, hot, or pressure stimuli is usually caused by sensitivity to which tissue:
dentin/pulp/enamel/cementum
dentin
112
name the dental hard tissues
enamel, dentin, cementum, bone
113
what is the embryological origin of enamel
enamel organ
114
what is the embryological origin of dentin
dental papilla
115
what is the embryological origin of cementum
dental sac (follicle)
116
what is the embryological origin of alveolar bone
mesoderm
117
what type of tissue is enamel
epithelial
118
what type of tissue is dentin
CT
119
what type of tissue is cementum
CT
120
what type of tissue is alveolar bone
CT
121
the only dental hard tissue that is epithelial is __. all other are __
enamel
| CT
122
what are the incremental lines in enamel called
lines of Retzius
123
what are the incremental lines in dentin called
imbrication lines of von Ebner
124
what are the incremental lines in cementum called
arrest and reversal lines
125
what are the incremental lines in alveolar bone called
arrest and reversal lines
126
Enamel:
1. the formative cells of are the
2. the resorptive cells are
1. ameloblast
| 2. odontoclast
127
Dentin
1. the formative cells of are the
2. the resorptive cells are
1 odontoblast
| 2. odontoclast
128
dentin, enamel, and alveolar bone all have the same resorptive cells called
odontoclast
| note only cementum is different
129
Cementum
1. the formative cells of are the
2. the resorptive cells are
1. cementoblast
| 2. cementoclast
130
Alveolar bone
1. the formative cells of are the
2. the resorptive cells are
1. osteoblast
| 2. osteoclast
131
tissue formation after eruption occurs in all the dental hard tissues except
enamel
132
what is the only vascular dental HARD tissue
alveolar bone
133
is enamel, dentin, or cementum vascular
no
134
what dental hard tissues are innervated
alveolar bone and dentin
135
dentin has vascularity/innervation?
only innervated, not vascular
136
give the percent inorganic content of all the hard tissues
E: 96
D: 70
C: 65
AB: 60
137
give the percent organic content of all the hard tissues
E: 1
D: 20
C: 23
D: 25
138
As dental pulp ages the number of cells __ and the number of collagen fibers__
decrease
| increase
139
as pulp ages: what 3 things decreases
intracellular substance, water, and cells: major decrease in the # of undifferentiated mesenchymal cells. =size of pulp cavity due to the addition of secondary or tertiary dentin
140
as pulp ages: what 2 things increases
number of collagen fibers and calcifications w/in the pulp called denticles or pulp stones
141
as pulp ages it becomes more fibrotic leading to less _ capacity of pulp
regenerative
142
the ONLY type of NERVE ENDING found in the pulp is
FREE NERVE ENDING = specific receptor for pain
143
the pain receptors (free nerve endings) are located in the
plexus of Raschkow
144
regardless of the source of stimulation of free nerve endings in the plexus of Raschkow the only response is
pain
145
the pulp contains both myelinated and unmyelinated nerve fibers. which is more abundant
myelinated
146
myelinated nerve fibers are
sensory or afferent neurons axons that are located in the dentinal tubules in dentin
147
the unmyelinated fibers are __
sympathetic and associated with BVs
148
are proprioceptors found in the pulp (respond to stimuli regarding movement)
no
149
nodular calcified bodies having an organic matrix and occur frequently in relation to the coronal pulp
pulp stones
150
there are 2 types of pulp stones that can be free within the pulp or attached to the dentinal wall. name them
true and false
151
___ pulp stones are composed predominantly of dentin and have dentinal tubules. they may have an outer layer of predentin ad are often located adjacent to odontoblast cells
true
152
false pulp stones are composed of concentric layers of calcified material with no ___
tubular structures
153
__ pulp stones are surrounded on all sides by pulpal tissue and are not attached to the dentinal wall
free
154
_pulp stones are surrounded by reactionary or secondary dentin
embedded
155
which of the following has the least amount of collagen:
| bone, dentin, enamel, cementum
enamel
156
the hardest calcified tissue in the human body
enamel
157
the tissue richest in calcium
enamel
158
does enamel have cells
none
159
enamel = (germ layer)?
ectodermal
160
enamel's organic matrix is mainly protein, which is rich in which amino acid
proline
161
the morphologic unit of enamel
enamel rod/prism
162
most enamel rods extend the width of enamel from DEJ to the outer surface. T/F
true
163
the specific shape of the enamel rod is dictated by the __ of the ameloblast
Tomes' process
164
in most cases, enamel is _ shaped in the longitudinal section
cylindrical (4micrometers)
165
the oldest enamel in fully erupted tooth is located at the
DEJ underlying a cusp or cingulum
166
when do ameloblasts lose their functional ability
when the crown of the tooth has completed = therefore no power or regeneration
167
does enamel have power of metabolism
no
168
can enamel combat bacterial invasion
no
169
does enamel have a nerve supply?
no
170
enamel is a _ thermal insulator
good
171
topical application of fluorides in dental caries prevention reduces the
acid solubility of enamel
172
__ is the loss of teeth structure by mechanical forces from opposing teeth
Attrition
173
all of the following are changes in enamel except one:
a. attrition
b. discoloration
c. flattening of groove and fissures
d. modifications in the surface layer
e. increased permeability
increased permeability
aging enamel will be less permeable
174
enamel is a nonvital tissue t/f
true
175
enamel is capable of regeneration t/f
false
176
with increasing age, enamel will become ___ which is linked to the apparent ___(reduction/increase) in incidence of caries
discolored, reduce in permeability, modification in the surface layer
DECREASE
177
teeth darken with age. T/f
true
178
dentin becomes __ with age (thicker or thinner)
thicker
179
enamel becomes _ permeable with age (more/less)
less
180
young enamel behaves as a semipermeable membrane permitting water and small substances thru pores bw the crystals. with age the pores will __ as the crystals acquire more ions and as the surface increases in size
diminish
181
as you get older, there is a ___ (increase/decrease) in fluoride content in the surface of enamel
increase
182
T/F enamel tufts and lamellae may be likened to geologic faults and have no clinical significance.
true
183
the striae of Retzius often extend from the DEJ to the outer surface of enamel where they end in shallow furrows known as
perikymata
184
fan shaped HYPOcalcified structures of enamel rods that project from the DEJ into the enamel. they are found in the INNER 1/3 of enamel and represent areas of less mineralization.
enamel tufts
185
___are an anomaly of crystallization and seem to have no clinical importance
enamel tufts and enamel lamellae
186
___ represent short dentinal tubules near the DEJ that result from odontoblasts that crossed the BM before it mineralized into the DEJ. the dentinal tubules became trapped during apposition of the enamel matrix and enamel became mineralized around them.
enamel spindles
187
enamel spindles may serve as
pain receptors
188
__ are partially calcified vertical defects in the enamel resembling cracks or fractures that travers the entire length of the crown from the surface to the DEJ. they are narrower and longer than enamel tufts
enamel lamellae
189
over the cusps of teeth the enamel rods appear twisted around each other in complex arrangement
gnarled enamel
190
as tooth erupts it is covered by a _ consisting of debris from the enamel organ that is lost rapidly
pellicle
191
_ optical phenomenon produced by changes in direction bw adjacent groups of enamel rods.
Hunter-Schreger bands
192
Hunter-Schreger bands are seen most clearly in _ ground sections viewed by reflected light and are found in the __ of the enamel
longitudinal
inner 2/3 of the enamel
193
the incremental (or imbrication) lines of vonEbner in dentin are similar to the growth rings/incremental ___ in enamel
lines of Retzius
194
__ are dark bands seen in dentin.
contour lines of Owen
195
contour lines of Owen represent a
disturbance in body metabolism that affects the odontoblasts by altering their formation efforts
196
Tomes' granular layer is most often found
in peripheral portion of the dentin beneath the root's cementum adjacent to the DCJ.
197
enamel formation begins at the future cusp and spreads down the cusp slope. As the ameloblasts retreat in incremental steps, the ameloblasts create an artifact in the enamel called the
lines of Retzius
198
one line of Retzius is accentuated and is more obvious than the others. it is called the
neonatal line (marks division bw enamel formed before birth and the enamel formed after birth)
199
neonatal line is found in which deciduous teeth
all of them
200
neonatal line is found in which permanent teeth
in the larger cusps of the permanent 1st molars
201
the organic phase of dentin is about 90% collagen, mainly type __ with small amounts of type _ and _
type I majority
| type III and IV minority
202
_ makes up the bulk of the tooth
dentin
203
dentin extends
almost the entire length of the tooth
204
Calcium hydroxyapatite formula
Ca10(PO4)6(OH)2
205
are fluoride and carbonate minerals present in dentin
yes
206
unlike enamel which is acellular dentin has a
cellular component that is retained after its formation by odontoblasts
207
dentin and pulp are both formed by
dental papilla
208
pulp tissue is very loose/dense
loose and vascular
209
is pulp tissue calcified
no
210
is dentin vascular
no
211
the main cell type in dentin is the
odontoblast
212
the odontoblast is derived from
ectomesenchyme
213
dentin is more flexible than enamel = (__ modulus of elasticity)
lower
214
dentin's compressive strength is much ___ than its tensile strength
higher
215
dentin is _ mineralized than cementum or bone
more
216
morphologically and chemically dentin has many characteristics in common with _
bone
217
orthodontic movement of teeth ALWAYS causes remodeling of the alveolar bone to accommodate movement of the teeth. T/f
true
218
the new alveolar bone deposited during ortho treatment is
intramembranous
219
the bone-forming cells that secrete the collagen and minerals needed to lay down new bone
osteoblasts (from mesenchyme)
220
osteoblasts that have been trapped in the osteoid produced by other surrounding osteoblasts are called
osteocytes
221
osteocytes/osteoblasts maintain bones, play a role in controlling extracellular concentration of calcium and phosphate and are directly stimulated by calcitonin and inhibited by PTH
osteocytes
222
osteoclasts are derived from
stem cells in bone marrow- the same ones that produce monocytes and macrophages
223
osteoclasts are bone_ cells
resorbing
224
the alternate loosening and tightening of a deciduous tooth before it is lost is caused by alternate _ and _ of cementum and bone
resorption and apposition
225
the alternate loosening and tightening of a deciduous tooth before it is lost is caused by alternate resorption by __ and ___ and appostion by __ and __
resorption: osteoclasts and cementoclast
appostion: cementoblast and osteoblast
226
during active tooth eruption, there is __ of bone on all surfaces of the alveolar crest and on all walls of the bony socket
apposition
227
permanent teeth move _ and _ when erupting
occlusally and facially
228
apical abscesses of which teeth have a marked tendency to produce cervical spread of infection most rapidly
mandibular 2nd and 3rd molars
229
certain anatomical features determine to a large extent the actual direction that infection may take. the attachment of muscles may determine the route that the infection will take, channeling the infection into certain tissues. t/f
true
230
a lesion in submandibular skin region most commonly affects which teeth
mandibular 2nd and 3rd molars if roots are inferior to the mylohyoid
231
a lesion in the sublingual region most commonly affects which teeth
mandibular 1st and 2nd molar if lingual root is SHORT and SUPERIOR to the mylohyoid
232
a lesion in submental skin region most commonly affects which teeth
mandibular incisors if the root is long and inferior to mentalis
233
a lesion in buccal skin surface region most commonly affects which teeth
maxillary molars if buccal roots are superior to buccinator
234
a perforation into max sinus region most commonly affects which teeth
maxillary molars if buccal roots are long
235
a lesion in the palate region most commonly affects which teeth
maxillary lateral inscisors, premolars (lingual root), maxillary molars (palatal root)
236
a lesion of nasolabial skin region most commonly affects which teeth
maxillary canine if root is long and superior to levator anguili oris
237
penetration of nasal floor region most commonly affects which teeth
max central incisor
238
lesion of maxillary vestibule region most commonly affects which teeth
max CI and LI
max canine (if root is short and inferior to levator anguili oris)
max premolars
max molars (if buccal roots are short and inferior to buccinators)
239
a lesion in mandibular vestibule region most commonly affects which teeth
```
md incisors (if roots are short and superior to mentalis)
md canines and premolars (if roots are short and superior to depressors), mandibular 1st and 2nd molars (if roots are short and superior to buccinators)
```
240
the bone directly lining the socket (inner aspect of the alveolar bone) is referred to as
bundle bone
241
the alveolar __ Is the bone of the jaws that contain the alveoli (sockets) for the teeth
process
242
the alveolar process contains an outer (buccal and lingual) ___
cortical plate
243
the alveolar process contains a central __
spongiosa
244
the alveolar process contains a bone lining called
alveolar bone
245
the cortical plate and alveolar bone meet at the
alveolar crest (usually 2mm below the CEJ)
246
alveolar bone is aka
cribiform plate
247
in x rays the alveolar bone is referred to as
lamina dura bc increase radiopacity
248
the bone directly lining the socket (inner aspect of alveolar bone) is referred to as
bundle bone
249
PDL fibers attach to _bone
bundle
250
the cortical plate consists of layers of _ bone
lamellar
251
cortical plate is thinner/thicker in maxilla, and thickest on the __
thinner in maxilla
| thickest in the buccal aspect of MD PM's and molars
252
trabecular bone is absent in which region
anterior teeth. here the cortical plate and alveolar bone are fused together.
253
a newly erupted tooth has a membranous covering derived from what structure
oral epithelium
254
Nasmyth's membrane = the seconadary enamel cuticle, is the thin membrane covering __
newly erupted teeth
255
Nasmyth's membrane = the seconadary enamel cuticle is a remnant of the _ and is ectodermally derived
reduced enamel epithelium
256
Nasmyth's membrane = the seconadary enamel cuticle is produced what cells
ameloblasts after it produces the enamel rods
257
Nasmyth's membrane = the seconadary enamel cuticle has an inner clear and structureless and outer cellular layers that are abraded by
mastication
258
the seconadary enamel cuticle is seen microscopically as an amorphous material bw the
attachment epithelium and the tooth
259
the Nasmyth's membrane = the seconadary enamel cuticle is replaced by an ORGANIC deposit called
pellicle (from salivary PROTEINS)
260
it is the __ that is invaded by bacteria to form bacterial plaque that if not removed will cause dental caries and perio disease
pellicle
261
the __ enamel cuticle is the organic matrix responsible for binding the epithelium to the tooth during development
primary
262
Gaburnaculal canal
small canal located bw the PERMANENT tooth germ and the APEX of the deciduous tooth containing remnants of dental lamina and CT
263
after ameloblasts are finished w both enamel apposition and maturation they become part of the __
reduced enamel epithelium (along w other portions of the compressed enamel organ)
264
the __ fuses with the oral mucosa creating a canal to allow the enamel cusp tip to erupt thru the oral mucosa into the oral cavity.
reduced enamel epithelium
265
ameloblasts are lost forever t/f
true
266
dentin is considered a living tissue t/f
true
267
dentin is considered a living tissue because of odontoblastic cell processes known as
Tome's fiber
268
the Tome's fibers are
odontoblast processes that occupy the dentinal tubules. one per odontoblast
269
one theory of dentin sensitivity is that Tome's fibers are
receptors and transmit an impulse to pulpal nerves
270
the preferred theory of dentin sensitivity is that
fluid movement w/in the tubules, in response to stimulus, triggers the pulp nerves
271
the odontoblasts begin dentin formation (dentinogenesis) ___ before __
immediately before enamel formation by ameloblasts
272
dentinogenesis begins w/ odontoblasts laying down___ moving which way
dentin matrix aka predentin
| move away from DEJ toward the pulp
273
the most recently formed layer of dentin is always adjacent to the
pulp surface
274
predentin or dentin matrix is _ origin w/non mineralized collagen fibers
mesenchyme
275
Tomes' fiber vs Tomes' process?
Tomes' process = ameloblast
| Tomes' fiber = odontoblast
276
the cell body of the odontoblast lies in the
pulp cavity
277
the dentin tubules are _ shaped in the crown due to
S shaped (curvature) due to overcrowding of odontoblasts.
278
the curvature of the dentin tubules (S-shape) decreases in _ dentin
root
279
T/F tertiary dentin is produced only by those cells DIRECTLY affected by the stimulus
true
280
__ dentin is produced in reaction to various stimuli, such as attrition, caries, or restorative dentin procedure
teritary
281
unlike primary or secondary dentin that forms along the entire pulp-dentin border, tertiary dentin is produced only by those cells
directly affected by the stimulus
282
reactionary dentin is deposited by __ odontoblast
pre-existing
283
reparative dentin is deposited by__ odontoblst-like cells
newly differentiated
284
__ dentin is the dentin formed in a tooth BEFORE THE COMPLETION of the apical foramen
primary
285
primary dentin is characterized by a _ pattern of tubules
regular
286
__ dentin is the dentin formed in a tooth AFTER THE COMPLETION of the apical foramen
secondary
287
secondary dentin is formed at a __ rate than primary dentin and is _ mineralized
slower, less
288
the junction of primary and secondary dentin is characterized by a
sharp change in direction of dentinal tubules
289
when dentin is damaged, by injury/caries/ odontoblastic processes will
die or retract = leaving empty dentinal tubule called dead tracts - dark areas in ground sections of tooth
290
with time the dead tracts become completely filled w calcified material called
sclerotic dentin
291
when sclerotic dentin fills the dead tracts (dark), it is called ___ and appears _ in ground sections of the tooth
blind tracts
| white
292
the adaptive advantage of blind tracts over dead tracts is
the dentinal tubules have been sealed off to prevent bacteria from entering the pulp.
293
clinically sclerotic dentin appears
dark, smooth, shiny
