Oral Cavity and Tooth development -Part 2 Flashcards
1
Q
what are teeth grossly divided into
A
root and crown
2
Q
what is the tooth root
A
portion of tooth embedded in bone
3
Q
where is the tooth root located
A
in part of the jaw called alveolar ridge, in the tooth socket called the alveolus
4
Q
what is the crown
A
the portion of the tooth that projects into oral cavity
5
Q
what is the enamel
A
a highly mineralized layer that protects the crown
6
Q
describe enamel
A
hard, translucent substance, containing less than 1% organic material and 96-98% hydroxyapatite
7
Q
what does enamel derive from embryologically
A
ectoderm
8
Q
what is enamel secreted by
A
tall, columnar ameloblasts of enamel organ
9
Q
what are tome’s processes
A
apical, secretory end of ameloblast
10
Q
what is the formation of enamel rods due to
A
enamel mineralization not being uniform
11
Q
what are enamel rods separated by
A
interprismatic material
12
Q
where do enamel rods extend from
A
ameloblasts at enamel surface to dentino-enamel junction
13
Q
what is dentin embryologically derived from
A
mesoderm
14
Q
what is the bulk of the tooth composed of
A
dentin
15
Q
what secretes dentin
A
odontoblasts of dental papilla as non-mineralized pre-dentin
16
Q
what is dentin chemically similar to
A
bone but more mineralized ~70% hydroxyapatite crystals
17
Q
what does dentin contain
A
type 1 collagen and GAGs
18
Q
what is dentin arranged in
A
dentin tubules
19
Q
what do dentin tubules radiate from
A
pulp cavity
20
Q
what do dentine tubules contain
A
long rod-like cytoplasmic processes of odontoblasts (Tome’s processes)
21
Q
what does the pulp cavity contain
A
support structures such as sensory nerves and blood vessels
22
Q
what is dentin innervated by
A
myelinated nerves
23
Q
what is dental pulp embryologically derived from
A
mesoderm
24
Q
what does dental pulp resemble
A
primitive mesenchyme
25
what does dental pulp contain
stellate fibroblasts, reticular fibers, collagen and ground substance
26
what is dental pulp supplied by
capillaries from arterioles running with periodontal ligament
27
what is the tooth root covered by
a thin layer of cementum
28
what is cementum embryologically derived from
mesoderm
29
what is cementum
amorphous, collagen-based, calcified tissue ~45-50% hydroxyapatite, similar to bone
30
what makes cementum
cementoblasts that mature into cementocytes
31
what are cementoblasts/cementocytes similar to
osteoblasts/osteocytes
32
what anchors the cementum layer to bone of alveolus
fibers of periodontal ligament or membrane
33
what is the periodontal ligament composed of
dense, collagenous fibers called sharpeys fibers
34
what do sharpeys fibers do
run at an oblique angle to support tooth in socket and allow slight movement of tooth during mastication
35
what are epithelial rests of Malassez
occasional clusters of epithelial cells within periodontal ligament
36
what is the neck of the tooth
the region of tooth between root and crown
37
what protects the gingiva
masticatory oral mucosa
38
what does the gingiva cover
upper portion of alveolar ridge
39
what does attached gingiva cover
upper alveolar bone
40
what does free gingiva form
cuff or neck of tooth
41
what is the space between the free gingiva and crown called
gingival sulcus or crevice
42
what the gingival sulcus lined by
crevicular epithelium
43
what is the periodontium
tissues that surround and support tooth
44
what does the periodontium include
epithelium, cementum, periodontal ligament and alveolar bone
45
what 2 opposing layers form the tooth and what is their origin
ameloblasts of enamel organ and odontoblasts of dental papilla
46
what tooth structures are derived from ectoderm
enamel
47
what tooth structures are derived from mesoderm
dentin, cementum, pulp, and periodontal ligament
48
what happens in the 6th week of fetal development
a horseshoe shaped epithelial ridge arises from oral epithelium which forms the dental lamina in position of future jaws
49
what forms in each quadrant
lamina develops globular, ectodermal swellings ( one for each deciduous tooth) -> superficial half forms enamel organs and deep half forms dental papilla
50
what happens in the cap stage
enamel organ initially cup shaped
51
what do the cells of enamel organ progressively differentiate into
stellate reticulum with ECM of GAGs
52
what comes after the cap stage
bell stage
53
what do the cells lining the outer convex surface of the enamel organ become in the bell stage
external enamel epithelium
54
what do the cells lining concave surfaces of the enamel organ form in the bell stage
internal enamel epithelium that differentiate into tall columnar ameloblasts
55
what is amelogenesis
enamel formation
56
where is the dental papilla located
deep to developing enamel organs
57
what do cells lining convex surface of dental papilla develop into
odontoblasts
58
what is dentinogenesis
dentin formation
59
what does the development of ameloblasts induce
differentiaition of odontoblasts
60
what does calcification of dentin induce
deposition of enamel
61
what is tooth formation initiated by
deposition of organic pre-dentin by odontoblasts on surface of dental papilla that is later calcified into dentin
62
what does the calcification of dentin matrix secondarily induce
enamel production by ameloblasts
63
where are odontoblasts processes located
embedded in dentin matrix to form dentin tubules
64
what does enamel form in and what is it separated by
forms in mineralized columns of enamel rods separated by less mineralized interprismatic material
65
what happens after the deposit of dentin and enamel
dental lamina fragments and atrophies
66
what happens at tooth eruption to enamel organ and ameloblasts
they degenerate
67
what separates as the tooth erupts
overlying mucosa
68
what does the dental papilla become as it shrinks
dental pulp surrounded by dentin
69
what continues to be produced after tooth formation is complete
small amounts of secondary dentin
70
what determines the 3D shape of the tooth crown
overall shape of enamel organ
71
what is the epithelial sheath of Hertwig
outer rim of enamel organ
72
what does the epithelial sheath of Hertwig determine
cross sectional outline of tooth
73
what does the surrounding mesenchyme form
dental follicle -> periodontal ligament
74
what do enamel organs of permanent teeth develop as buds from
dental lamina and deciduous enamel organ
75
what does the dental lamina proliferate as in molars
caudally to form enamel organs of secondary dentition
76
when does tooth development begin
at 6th week of fetal development
77
how many roots do incisors and canines have
1 root
78
how many roots do premolars usually have
2 roots
79
how many roots do molars usually have
2-4 roots
80
when should you not prescribe tetracycline and why
during development of permanent dentition because it causes yellow discoloration of teeth
81
do molars have precursors
no
82
what is the human dental formula
I 2/2, C 1/1, P 2/2, M 3/3
83
what are incisors function
cutting and biting
84
what is canine function
puncturing and holding
85
what are premolars and molars used for
grinding
86
what does TMJ allow for
lateral and anterior-posterior motion important for chewing and grinding
87
what are cusps
raised points on occlusal surfaces of molars and premolars
88
what are the types of cusps
protocone, metacone and paracone
89
what is talonid
flattened posterior surface of lower molars
90
what is bunodont
low crowned premolars and molars in omnivores
91
what is hypsodont
tall and high crowned premolars and molars in herbivores
92
what is orthodontia accomplished by
osteoblast and osteoclast activity in alveolus
93
what are dental caries
results when weak acids in food and drink erode calcified enamel augmented by bacterial infection
94
what does fluoride do
hardens enamel and kills bacteria
95
what is a root canal
when caries extend into dentin or pulp cavity to produce abscesses or death of tooth
96
what is periodontal disease caused by
accumulation of calcified food and bacterial debris (plaque) in gingival sulcus that results in widening of gingival sulcus, possible inflammation and destruction of periodontal ligament
97
what is gingivitis
inflammation of gums
98
what is periodontitis
inflammation of periodontal ligament
