Tooth Development Flashcards
1
Q
define histogenesis
A
differentiation of undifferentiated cells to make new tissues
2
Q
define mineralised dental tissues
A
enamel, dentine, and cementum
3
Q
define unmineralised dental tissues
A
dental pulp
periodontium
4
Q
define dental lamina
A
contributes to development of teeth
5
Q
define vastibular lamina
A
contributes to the vestibule of the mouth, delineating the lips and cheek from the teeth formation of the sulcus
6
Q
define initiation stage
A
first stage of tooth development
7
Q
define bud stage
A
second stage of tooth development
8
Q
define cap stage
A
third stage of tooth development, in which the tooth germ grows into a cap stage
9
Q
define bell stage
A
fourth stage, in which differentiation occurs to furthest extent and starts to resemble a bell
10
Q
define crown stage
A
fully developed tooth
11
Q
define external enamel epithelium
A
outer layer of cuboidal cells that limits the enamel organ
12
Q
define stellate reticulum
A
of epithelial origin, behave like mesenchymal cells, synthesis of collagen I, II and III
13
Q
define stratum intermedium
A
two or three layers of cells sitting above IEE
14
Q
define inner enamel epithelium
A
columnar shaped cells rich in RNA, connected to each other by desmosomes
15
Q
define ectomesenchyme
A
interesting group of cells whose origin is very controversial. Some think neural crest others mesodermal somites
16
Q
at what week does mesenchyme migrate in to initiate events of tooth development
A
week 6
17
Q
to allow condensation of ectomesenchyme to occur what protein switches on what growth factor?
A
protein - lef-one switches on fgf8
18
Q
what does the primary epithelial band give rise to?
A
dental lamina
vestibular lamina
19
Q
what does the vestibular lamina form?
A
vestibule between teeth and lips/cheek
20
Q
what does the lingual side of the primary epithelial band give rise to?
A
dental lamina
21
Q
what does the labial/buccal side of the primary epithelial band give rise to?
A
vestibular lamina
22
Q
does the formation of the tooth bud take place at the dental lamina or vestibular lamina?
A
dental lamina
23
Q
how does the vestibule form?
A
signals tell cells to die off
24
Q
by what week should the vestibule be formed?
A
12
25
tooth development is 3 overlapping phases, what are they?
initiation
morphogenesis
histogenesis
26
what does the epithelium in tooth development give rise to?
enamel
hyaline layer of root
27
what does the mesenchyme in tooth development give rise to?
dentine
pulp
cementum
periodontium - PDL and bone
28
at what week does initatiation of tooth development take place?
6
29
which tissue initiates tooth development?
epithelium
30
what are the stages of tooth development?
bud stage
cap stage
bell stage
crown stage
late bell stage
31
what are the contents of the tooth germ?
enamel organ
dental papilla
dental follicle
32
what are the 4 layers of the enamel organ?
inner enamel epithelium
stratum intermedium
stellate reticulum
outer enamel epithelium
33
what does the dental papilla form
odontoblasts (dentine) and pulp
34
what does the dental follicle form?
cementum, PDL and bone
35
what is the role of inner enamel epithelium?
forms ameloblasts which form enamel
36
what is the role of stratum intermedium?
synthesis and transport to from IEE
37
what is the role of the stellate reticulum?
maintenance of shape and protection
38
what is the role of the outer enamel epithelium?
maintenance of shape and exchange
39
what are enamel knots?
area of developing enamel which sends out signals
40
what is enamel niche?
as dental lamina breaks down, it surrounds the outside
41
what is the enamel septum?
forms between outer and inner epithelium cells, changes shape from cap to bell
42
what growth factors diffuse into mesenchyme. bind to cells and switch on gene msx1 and stop pax9 from developing to allow the tooth to start to initiate?
small cytokines
43
what genes are activated in repsonse to factors being produced in the mesenchyme in the bud stage once msx1 and pax9 are switched on?
msx2, p21, bmp2
44
what genes are involved in enamel knot signalling?
the switch on by msx2 and p21 of a certain amount of cell death
45
what genes are activated in the cap stage?
gfg4 and 9
46
the interaction of what 2 things will determine how the tooth develops in terms of shape, root and ability to erupt?
ameloblasts
odontoblasts
47
does dental epithelium or oral epithelium initiate tooth development?
dental epithelium
48
what is the purpose of the extracellular matrix in tooth development?
allows cells factors to be switched on, allowing the cells to interact
enables cells adhesion and migration, providing an area for cells to proliferate in
49
what is the expression of the bud stage?
dental mesenchyme
50
what is the expression of the cap stage?
enamel knot, dental papilla, dental sac
51
what is the expression of the bell stage?
dental papilla
52
what is the expression of the late bell stage?
dental papilla, preodontoblasts
53
by what week does crown formation begin (bell stage)?
14
54
what type of cells divide and start to form the root?
cervical loop cells
55
what type of cells mature in odontoblasts?
Dental papilla cells
56
what type of cells mature into ameloblasts?
Inner Enamel Epithelium cells
57
what do odontoblasts form?
predentine and dentine
58
what do ameloblasts form?
enamel
59
what is the cervical loop?
where the outer enamel epithelium cells meet the inner enamel epithelium cells
most cervical part of the enamel organ
60
what is cervical loop proliferation induced by?
mesenchymal cells of the dental papilla
61
what are the stages of life as an ameloblast?
pre-secretory
secretory
transition
maturation
postmaturation
62
what is pre dentine?
the organic matrix that makes up dentine before its calcified
63
what is dentine?
mineralised pre-dentine
64
what is enamel?
2 groups
amelogenins make up 90-95%
enamelins make up 5-10%
65
what stage does tooth morphogenesis take place?
late cap stage/early bell stage
66
where does the signal for tooth shape take place?
dental papilla
67
does an incisor or molar require more areas of maturation to take place?
molar
68
the only area within the oral cavity where pit x2 is expressed is where?
dental epithelium
69
for tooth development to occur what must be switched on?
pit x2
70
expression of what drives incisor development?
MSX1 and 2
71
expression of what drives molar development?
BarX1 and DLX1 and 2
72
What gene determines where teeth form?
PITX2
73
What will the reduced enamel epithelium eventually form?
junctional epithelium
74
when the succession of the secondary dentition happens what side does the tooth erupt from, labial or lingual?
lingual
75
what is it known as a tooth erupts from the secondary dentition on the labial side?
tooth gland lamina
76
for anodontia to occur what has happened?
something has gone wrong during initiation stage with expression of the genes
77
for supernumerary to occur what has happened?
over expression of one of the genes in the initiation stage
78
for microdontia/macrodontia to occur what stage has their been a disruption in?
bud stage
79
what dental developmental disturbances can occur in the cap stage?
dens in dente
fusion and germination
80
for crown development:
Epithelium -> ameloblasts = ?
enamel
81
for crown development:
dental papilla -> odontoblasts = ?
dentine
82
for root development:
dental papilla -> odontoblasts = ?
dentine
83
for root development:
dental follicle -> cementoblasts = ?
cementum
84
what is root development driven by?
hertwig's epitheial root sheath
85
other than hertwig's epitheial root sheath, what else aids in root formation?
dental follicle
86
what are the 3 layers of the dental follicle?
inner investing layer
loose connective tissue
outer layer
87
what 3 things make up root structure?
root dentine
cementum
periodontal ligament
88
there is a layer of enamel proteins on the dentine layer, what is the purpose of this?
allow cementoblasts to attach to start forming the cementum
89
the enamel matrix proteins on the dentine layer form a layer called what?
hyaline layer of hopewell smith
90
dental follicle cells receive signals from what to allow them to differentiate into cementoblasts, fibroblasts, osteoblasts etc
HERS
91
Dental papilla in response to what signals will start forming root odontoblasts to form root dentine?
HERS
92
What does the hyaline layer of hopewell smith start off as?
enamel matrix proteins
93
where does the hyaline layer pf hopewell smith lie?
between dentine and cementum
94
what is cementogenesis?
formation of cementum
95
what are the 2 types of cementum?
acellular (primary)
cellular (secondary)
96
what type of cells cause osteogenic differentiation?
HERS cells
97
what are the main cell type found in the PDL?
Spindle-shaped fibroblasts
98
what is the intermediate plexus?
Intermediate between the bone and the cementum in actively erupting teeth (or orthodontic movements) the fibers of the periodontal ligament form a plexus of intermingling fibers
99
what are the 3 stages of dentine formation?
cytodifferntiation
matrix formation
mineralisation
100
what are the 2 types of dentine?
mantle dentine
circumpulpal dentine
101
what is hydroxyapatite?
a form of calcium apatite, also known as calcium phosphate, and is a naturally occurring mineral that makes up our bones and teeth
102
what do hydroxyapatite crystals form?
calcospherites
103
what is mantle dentine?
very first formed dentine
supports the overlying enamel layer
104
what is circumpulpal dentine?
the rest of dentine
formed before root formation is completed
105
what is active tooth eruption?
bodily movement of the tooth
106
what is passive eruption?
uncovering of the tooth by apical gingival migration
107
what position do successional teeth move from?
lingual/palatal position
108
what is intraosseous tooth eruption?
involves the formation of root of a tooth which allows the tooth to erupt from the bone
109
what is supraosseous tooth eruption?
consists of infragingival eruption and supragingival eruption.
110
what eruption comes first, intraosseous or supraosseous?
intraosseous
