11/7: Teeth Flashcards
(111 cards)
1
Q
What are teeth grossly divided into?
A
Root and crown
2
Q
What is the portion of the tooth embedded in bone?
A
Tooth root
3
Q
What is the pat of jaw that a tooth is embedded in?
A
Alveolar ridge
4
Q
What is the tooth socket called?
A
Alveolus
5
Q
What is the portion of tooth that projects into oral cavity?
A
Crown
6
Q
What are teeth protected by?
A
A layer of highly mineralized enamel, covers crown
7
Q
What is enamel?
A
a hard, translucent substance, containing < 1% organic material & 96-98% hydroxyapatite
8
Q
What is enamel secreted by?
A
Tall, columnar ameloblasts of enamel organ
9
Q
When do ameloblasts degenerate?
A
When the tooth erupts, after which enamel cannot be replaced by new synthesis
10
Q
What do secretory ends of ameloblasts form?
A
Single, large process, Tome’s process (microtubules and secretory vesicles)
11
Q
Explain enamel mineralization
A
Non-uniform, resulting in highly calcified enamel rods or prisms - roughly hexagonal
12
Q
What is enamel separated by?
A
Interprismatic material
13
Q
Where do enamel rods extend from?
A
Ameloblasts at enamel surface to dentino-enamel junction
14
Q
What is the bulk of tooth composed of?
A
Less mineralized dentine
15
Q
What is dentine secreted by?
A
Odontoblasts of dental papilla as non-mineralized pre-dentine
16
Q
Explain the components of dentine?
A
Chemically similar to bone, but more mineralized; ~70-80% hydroxyapatite crystals
17
Q
What plays a key role in mineralization of dentine matrix (like odontoblasts)?
A
Matrix vacuoles (Ca2+ and PO4-)
18
Q
What else does dentine contain?
A
Type I collagen and GAG’s
19
Q
How is dentine arranged?
A
In dentine tubules
20
Q
What are dentine tubules?
A
Hollow, parallel tubes radiating from pulp cavity
21
Q
What do dentine tubules contain?
A
Long, rod-like cytoplasmic process of odontoblasts (aka Tome’s fibers)
22
Q
What does the central pulp cavity contain?
A
Support structures - sensory nerves and blood vessels
23
Q
What is dentine innervated by?
A
Myelinated nerves
24
Q
Describe dental pulps origin
A
Mesodermal in origin
25
What does dental pulp resemble?
Primitive mesenchyme
26
What does dental pulp contain?
Sellate fibroblasts, reticular fibers, collagen, and ground substance
27
What is dental pulp supplied by?
Capillaries from arterioles running with periodontal ligament
28
What is the tooth root covered by?
Cementum
29
What is cementum manufactured by?
cementoblasts
30
What do cementoblasts mature into?
Cementocytes
31
What do cementocytes that lie against the surface of the periodontal ligament produce?
New cementum by appositional growth
32
What is similar to osteoblasts/cytes structurally and functionally?
Cementocytes
33
What is the region of the tooth between root and crown?
Neck of tooth
34
What is the neck of tooth protected by?
Masticatory oral mucosa called gingiva
35
What does the gingiva cover?
Upper portion of alveolar ridge
36
What is gingiva sometimes divided into/
Attached gingiba
37
What does attached gingiva cover?
Upper alveolar bone and free gingiva (forms cuff ~ neck of tooth)
38
What is the spave between free gingiva and crown called?
Gingival sulcus or crevice
39
What is the gingiva lined by?
Cervicular epithelium
40
What is crevicular epithelium easily breached by?
Bacteria -> periodontal disease, gingivitis
41
What is tissue that surround and support tooth referred to as?
Periodontium
42
What is included in periodontium?
Epithelium, cementum, peridontal ligament, and alveolar bone
43
How is cementum layer anchored to bone of alveolus?
With gibers of periodontal ligament or membrane
44
What is periodontal ligament composed of?
Dense, collagenous fibers, called Sharpey's fibers
45
How do Sharpey's fibers run?
At oblique angle, support tooth in socket
46
What do Sharpey's fibers allow?
Slight movement of tooth during mastication
47
What are clusters of epithelial cells within periodontal ligament?
Vestigial epithelial rests (of Malassez)
48
Where is tooth formed in relation to epithelial cells?
Between opposing layers of epithelial cells
ameloblasts of enamel organ &
odontoblasts of dental papilla
49
What is the ectodermal origin?
Enamel
50
What are mesodermal origin?
Dentine, cementum, pulp, and periodontal ligament
51
When does odontogenesis occur?
6th week of fetal development
52
What does the epitheloium look like during the early bell stage of odontogenesis?
Horseshoe-shaped epithelial ridge arises from oral epithelium
53
What does the horeshoe epithelial form?
Dental lamina in position of future jaws
54
In each quadrant, what does lamina develop
Several globular, ectodermal swellings (one for each diciduous tooth)
55
What does the superficial half of the cap stage form?
Enamel organs
56
What does the deep half of the cap stage form?
Dental papilla
57
What are cells involved in the early bell stage?
loosely arranged stellate cells and peripheral alyer of cuboidal/low columnar eoithelium
58
Where do the cells of the early bell shape meet?
Cervical loop
59
What does the internal enamel epithelium differentiate into?
Layer of amelobalsts and 2-3 cells (think stratum intermedium)
60
What does mesenchyme condense to form?
Dental papillae
61
What develops at the junction with ameloblasts?
Row of odontoblasts
62
What does permanent teeth arise from?
Side-growth of dental lamina
63
What is the initial shape of enamel?
Cup shaped (Cap stage)
64
What becomes stellate reticulum?
Cells of enamel organ differentiate with extracellular matrix of GAG's
65
What does the outer part of the bell-shaped structure become?
External enamel epithelium
66
What do cells lining the concave surface of enamel organ form?
Internal enamel epithelium
67
What does internal enamel epithelium differentiate into?
Tall, columnar ameloblasts
68
What is enamel formation?
Amelogenesis
69
What are deep developing enamel organs?
Primitive mesenchyme
70
What does primitive mesenchyme develop into?
Dental papilla
71
Cells lining convex surface of dental papilla develop into?
Odontoblasts
72
What is dentine formation?
Dentinogenesis
73
What occurs to two cell layers in apposition?
Tooth forms between
74
What do the two cell layers form together?
Future incisors, canine and molars of primary dentition
75
What does development of ameloblasts induce?
Differentiation of odontoblasts
76
What does calcification of dentine induce?
Deposition of enamel
77
What is tooth formation initiated by?
Deposition of organic pre-dentine by odontoblasts on surface of dental papilla
78
What is pre-dentine layer calcified into?
Dentine
79
What does calcification of dentine matrix secondarily induce?
Enamel production by ameloblasats
80
What do odontoblasts have embedded into dentine matrix and what do they form?
Odontoblast processes; dentine tubules
81
What is enamel formed by?
Mineralized columns of enamel rods
82
What are enamel rods separated by?
Less mineralized inter prismatic material
83
What occurs to dental lamina?
Fragments and atrophies
84
What happens at the time of tooth eruption?
Enamel organ and ameloblasts degenerate
85
What happens to overlying mucosa as tooth erupts?
Separates as tooth erupts, exposing crown
86
What happens to the dental papilla as tooth erupts?
Shrinks, becomes dental pulp, surrounded by dentine
87
What is papillae enclosed by and become?
Dentine; pulp cavity
88
What is a proliferation of epithelial cells located at the cervical loop of the enamel organ?
Hertwig's root sheath
89
What does hertwig's root sheath initiate?
Formation of dentine in the root by causing the differentiation of odontoblasts from the dental papilla
90
When does the root sheath disintegrate?
With the periodontal ligament
91
What do residual pieces that do not completely disappear seen as?
Epithelial cell rests
92
What occurs after tooth formation if compelte?
Small amounts of secondary dentine continue to be produced
93
What is the outer rim of enamel organ known as?
Epithelial sheath of hertwig
94
What does the surrounding mesenchyme form?
Dental follicle -> periodontal ligament
95
What do enamel organs of permanent teeth develop as?
Buds from dental lamina and deciduous enamel organ
96
What does the dental lamina proliferate in the case of molars?
Caudally to form enamel organs of secondary dentition
97
When does tooth eruption occur?
6-30 months after birth
98
How many deciduous teeth?
20 - 2I, 1C, 2M/quadrant
99
How many roots in I and C?
1
100
How many roots in P?
2
101
How many roots in M?
2-4
102
What occurs between ages of 6-12?
Deciduous teeth replaced by permanent
103
What causes yellow discoloration of teeth?
Tetracycline administered during development of permanent dentition
104
What is orthodontia accomplished by?
osteoblast & osteoclast activity in alveolus
105
When do dental caries result?
When weak acids in food and drink erode calcified enamel, augmented by bacterial action
106
What does fluoride do to enamel?
Harden and kill bacteria
107
Where can caries extend into?
Dentine or pulp cavity, produce abscesses or death of tooth
108
What is caused by
accumulation of calcified food & bacterial debris (plaque) in gingival sulcus?
Periodontal disease
109
What does periodontal disease cause?
widening of gingival sulcus, possible inflammation & destruction of periodontal ligament
110
What is inflammation of gums?
Gingivitis
111
What is inflammation of periodontal ligament?
Periodontitis
