Oral Cavity and Tooth Development Part 2 Flashcards
(116 cards)
1
Q
teeth are grossly divided into (2)
A
root & crown
2
Q
Portion of tooth embedded in bone
A
tooth root
3
Q
where is the tooth root located
A
part of the jaw called the alveolar ridge, in tooth socket called alveolus
4
Q
portion of the tooth that projects into the oral cavity
A
crown
5
Q
Protected by layer of highly
mineralized —, covers crown
A
enamel
6
Q
Enamel
A
hard, translucent
substance, containing < 1% organic
material & 96-98% hydroxyapatite
7
Q
enamel is — in origin
A
ectodermal
8
Q
what is enamel secreted by
A
tall,
columnar ameloblastsof enamel organ
9
Q
Apical, secretory end of ameloblast
forms single, large process,
A
Tome’s
process
10
Q
Enamel mineralization is non-uniform,
resulting in highly calcified
A
enamel rods
or prisms
11
Q
enamel rods
or prisms
A
roughly hexagonal, ~4-8m
in diameter
12
Q
Separated by less mineralized
A
interprismatic material
13
Q
Enamel rods extend from
A
ameloblasts
at enamel surface to dentino-enamel
junction
14
Q
Bulk of tooth composed of less mineralized
A
dentine
15
Q
dentine is — in origin
A
mesodermal
16
Q
how is dentin secreted
A
odontoblasts of dental papilla as pre-dentine
17
Q
dentine compared to bone
A
Chemically similar to bone, but more mineralized; ~ 70% hydroxyapatite crystals
18
Q
what does dentine also contain (2)
A
Type I collagen & GAG’s
19
Q
Dentine arranged in
A
dentine tubules
20
Q
dentine tubules
A
hollow, parallel tubes radiating from pulp cavity
21
Q
contain long, rod-like cytoplasmic processes of odontoblasts called
A
Tome’s fibers
22
Q
Central pulp cavity contains
support structures such as (2)
A
sensory Nn & blood vessels
23
Q
Dentine innervated by
A
myelinated
Nn
24
Q
Dental pulp is — in
origin
A
mesodermal
25
dental pulp resembles primitive...
mesenchyme
26
dental pulp contains (4)
stellate fibroblasts
reticular fibers
collagen
ground substance
27
dental pulp is richly supplied by capillaries from
| arterioles running with
periodontal
| ligament
28
Tooth root is covered by a thin layer of
cementum
29
cementum is --- in origin
mesodermal
30
cementum
amorphous, collagen-based, calcified tissue
31
makeup of cementum
~45-50% hydroxyapatite, similar to bone
32
cementum is manufactured by ---, which mature into
cementoblasts
| cementocytes
33
cementoblasts/cytes are similar to --- both structurally and functionally
osteoblasts/cytes
34
Cementum layer anchored to bone
| of alveolus with fibers of
periodontal ligament or
| membrane
35
periodontal ligament is composed of
dense, collageous fibers, called Sharpey’s
| fibers
36
how do sharpeys fibers run?
at oblique angles
37
PD/sharpeys fibers support the
tooth in socket
38
PD allows for
slight movement of tooth
| during mastication
39
May see occasional clusters of
epithelial cells within periodontal
ligament called
vestigial epithelial rests
| of Malassez
40
Region of tooth between root & crown is --- of tooth
neck
41
neck is protected by masticatory oral mucosa called
gingiva
42
gingiva covers
upper portion of alveolar ridge
43
Sometimes divided into (2)
attached gingiva (covers upper alveolar bone) & free gingiva (forms cuff ~ neck of tooth)
44
Space between free gingiva & crown called
gingival sulcus or crevice
45
Lined by
crevicular epithelium
46
crevicular epithelium
very thin, only 2-3 cells thick, easily breached by bacteria
47
easily breached by bacteria
periodontal disease, gingivitis
48
Tissues that surround & support tooth collectively referred to as
periodontium
49
periodontium includes (4)
epithelium, cementum, periodontal ligament & alveolar bone
50
Tooth formed between opposing layers of
epithelial cells
51
ameloblasts of --- origin
enamel
52
odontoblasts of
dental papilla
53
Enamel—origin
ectodermal
54
Dentine, cementum, pulp, & periodontal ligament are ---
mesodermal
55
~6th week of fetal development, a horseshoe-shaped epithelial --- arises from oral epithelium
ridge
56
Forms ---- in position of future jaws
dental lamina
57
In each quadrant, lamina develops several globular, --- --- (one for each deciduous tooth)
ectodermal swellings
58
Superficial half forms --- ---; deep half forms --- ---
enamel organs
| dental papilla
59
Enamel organ initially --- shaped (cap stage)
cup
60
Cells of enamel organ progressively differentiate, become --- ---, with extracellular matrix of GAG’s
stellate reticulum
61
Later forms --- shaped structure (bellstage)
bell
62
Cells lining outer, convex surface of enamel organ become
external enamel epithelium
63
Cells lining concave surface of enamel organ form
internal enamel epithelium
64
Cells lining concave surface of enamel organ form internal enamel epithelium, differentiate into tall, columnar
ameloblasts
65
enamel formation
Amelogenesis
66
Deep to developing enamel organs is primitive mesenchyme; develops into --- ---
dental papilla
67
Cells lining convex surface of dental papilla develop into
odontoblasts
68
dentine formation
Dentinogenesis
69
These two cell layers in apposition—tooth forms --- them
between
70
Together they form future (3) of 1’ dentition
incisors, canine & molars
71
Development of ameloblasts induces
differentiation of ---, but
calcification of dentine induces
deposition of ---
odontoblasts
| enamel
72
Tooth formation initiated by deposition
of organic pre-dentineby odontoblasts
on surface of dental papilla—later
calcified into
dentine
73
Calcificaiton of dentine matrix
| secondarily induces
enamel production
| by ameloblasts
74
Odontoblasts have odontoblast
processes, embedded in dentine
matrix—form
dentine tubules
75
Enamel forms in mineralized columns of enamel rods, separated by less mineralized
interprismatic material
76
Subsequent to deposit of dentine & enamel, dental lamina (2)
fragments & atrophies
77
At time of tooth eruption, enamel organ & ameloblasts ---
degenerate
78
Overlying mucosa separates as tooth erupts, exposing ---
crown
79
Dental papilla shrinks, becomes --- ---, surrounded by dentine
dental pulp
80
After tooth formation is complete, small amounts of --- --- continue to be produced, may eventually obliterate pulp cavity
2’ dentine
81
Overall shape of enamel organ determines
3-D shape of tooth crown
82
Outer rim of enamel organ known as
epithelial sheath of Hertwig(= Hertwig’s root sheath)
83
epithelial sheath of Hertwig(= Hertwig’s root sheath) determines
cross-sectional outline of tooth
84
Surrounding mesenchyme forms
dental follicle
85
Surrounding mesenchyme forms dental follicle results in
periodontal ligament
86
Enamel organs of permanent teeth develop as buds from
dental lamina & “deciduous” enamel organ
87
In case of molars, dental lamina proliferates caudally to form
enamel organs of 2’ dentition
88
In humans, tooth development begins --- of fetal development
~6th week
89
tooth eruption does not occur until --- after birth
6-30 months
90
P usually -- roots
2
91
M usually -- roots
2-4
92
I & C -- roots each
1
93
Between--- of age, deciduous teeth replaced by permanent dentition
6-12 years
94
----, administered during development of permanent dentition incorporated into enamel
Tetracycline
95
Tetracycline, administered during development of permanent dentition incorporated into enamel results in
yellow discoloration of teeth
96
Distally, get further development of
| 3 M, sans precursors; erupt at
~6, 12, & 18-21 yrs of age, respectively
| => 32 teeth
97
Human dental formula
I 2/2, C 1/1,
| P 2/2, M 3/3
98
In --- dentition, all teeth similar
homodont
99
Incisors modified for (2)
cutting & biting
100
Canines for (2)
puncturing & holding
101
Premolars & molars generally used for (1)
grinding
102
TMJ allows lateral & --- motion—important for (2)
anterior-posterior
| chewing, grinding
103
Raised points on occlusal surfaces of molars & premolars known as ---
cusps
104
Raised points on occlusal surfaces of molars & premolars known as cusps (include (3))
protocone, metacone, paracone
105
Flattened posterior surface of lower molars known as
talonid
106
Premolars and molars can be low crowned, or ---, in omnivores, or may be very tall, high crowned, ---, as in herbivores
bunodont
| hypsodont
107
Premolars variously
modified (shearing carnassialsin carnivores)
108
Premolars variously modified (shearing --- in carnivores)
carnassials
109
Dental disorders (2)
Abnormal tooth eruption &/or misalignment
| Orthodontia
110
Orthodontia accomplished by
osteoblast & osteoclast activity in alveolus
111
Dental caries results when
weak acids in food & drink erode calcified enamel, augmented by bacterial action
112
--- helps harden enamel & kills bacteria
Fluoride
113
Caries may extend into dentine or pulp cavity, produce abscesses or death of tooth resulting in a
root canal
114
caused by accumulation of calcified food & bacterial debris (plaque) in gingival sulcus => widening of gingival sulcus, possible inflammation & destruction of periodontal ligament
Periodontal disease
115
Inflammation of gums
gingivitis
116
Inflammation of periodontal ligament
periodontitis
