Tooth Development Flashcards

1
Q

define histogenesis

A

differentiation of undifferentiated cells to make new tissues

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2
Q

define mineralised dental tissues

A

enamel, dentine, and cementum

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3
Q

define unmineralised dental tissues

A

dental pulp
periodontium

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4
Q

define dental lamina

A

contributes to development of teeth

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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

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6
Q

define initiation stage

A

first stage of tooth development

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7
Q

define bud stage

A

second stage of tooth development

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8
Q

define cap stage

A

third stage of tooth development, in which the tooth germ grows into a cap stage

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9
Q

define bell stage

A

fourth stage, in which differentiation occurs to furthest extent and starts to resemble a bell

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10
Q

define crown stage

A

fully developed tooth

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11
Q

define external enamel epithelium

A

outer layer of cuboidal cells that limits the enamel organ

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12
Q

define stellate reticulum

A

of epithelial origin, behave like mesenchymal cells, synthesis of collagen I, II and III

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13
Q

define stratum intermedium

A

two or three layers of cells sitting above IEE

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14
Q

define inner enamel epithelium

A

columnar shaped cells rich in RNA, connected to each other by desmosomes

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15
Q

define ectomesenchyme

A

interesting group of cells whose origin is very controversial. Some think neural crest others mesodermal somites

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16
Q

at what week does mesenchyme migrate in to initiate events of tooth development

A

week 6

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17
Q

to allow condensation of ectomesenchyme to occur what protein switches on what growth factor?

A

protein - lef-one switches on fgf8

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18
Q

what does the primary epithelial band give rise to?

A

dental lamina
vestibular lamina

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19
Q

what does the vestibular lamina form?

A

vestibule between teeth and lips/cheek

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20
Q

what does the lingual side of the primary epithelial band give rise to?

A

dental lamina

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21
Q

what does the labial/buccal side of the primary epithelial band give rise to?

A

vestibular lamina

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22
Q

does the formation of the tooth bud take place at the dental lamina or vestibular lamina?

A

dental lamina

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23
Q

how does the vestibule form?

A

signals tell cells to die off

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24
Q

by what week should the vestibule be formed?

A

12

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25
Q

tooth development is 3 overlapping phases, what are they?

A

initiation
morphogenesis
histogenesis

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26
Q

what does the epithelium in tooth development give rise to?

A

enamel
hyaline layer of root

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27
Q

what does the mesenchyme in tooth development give rise to?

A

dentine
pulp
cementum
periodontium - PDL and bone

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28
Q

at what week does initatiation of tooth development take place?

A

6

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29
Q

which tissue initiates tooth development?

A

epithelium

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30
Q

what are the stages of tooth development?

A

bud stage
cap stage
bell stage
crown stage
late bell stage

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31
Q

what are the contents of the tooth germ?

A

enamel organ
dental papilla
dental follicle

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32
Q

what are the 4 layers of the enamel organ?

A

inner enamel epithelium
stratum intermedium
stellate reticulum
outer enamel epithelium

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33
Q

what does the dental papilla form

A

odontoblasts (dentine) and pulp

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34
Q

what does the dental follicle form?

A

cementum, PDL and bone

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35
Q

what is the role of inner enamel epithelium?

A

forms ameloblasts which form enamel

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36
Q

what is the role of stratum intermedium?

A

synthesis and transport to from IEE

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37
Q

what is the role of the stellate reticulum?

A

maintenance of shape and protection

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38
Q

what is the role of the outer enamel epithelium?

A

maintenance of shape and exchange

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39
Q

what are enamel knots?

A

area of developing enamel which sends out signals

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40
Q

what is enamel niche?

A

as dental lamina breaks down, it surrounds the outside

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41
Q

what is the enamel septum?

A

forms between outer and inner epithelium cells, changes shape from cap to bell

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42
Q

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?

A

small cytokines

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43
Q

what genes are activated in repsonse to factors being produced in the mesenchyme in the bud stage once msx1 and pax9 are switched on?

A

msx2, p21, bmp2

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44
Q

what genes are involved in enamel knot signalling?

A

the switch on by msx2 and p21 of a certain amount of cell death

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45
Q

what genes are activated in the cap stage?

A

gfg4 and 9

46
Q

the interaction of what 2 things will determine how the tooth develops in terms of shape, root and ability to erupt?

A

ameloblasts
odontoblasts

47
Q

does dental epithelium or oral epithelium initiate tooth development?

A

dental epithelium

48
Q

what is the purpose of the extracellular matrix in tooth development?

A

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
Q

what is the expression of the bud stage?

A

dental mesenchyme

50
Q

what is the expression of the cap stage?

A

enamel knot, dental papilla, dental sac

51
Q

what is the expression of the bell stage?

A

dental papilla

52
Q

what is the expression of the late bell stage?

A

dental papilla, preodontoblasts

53
Q

by what week does crown formation begin (bell stage)?

A

14

54
Q

what type of cells divide and start to form the root?

A

cervical loop cells

55
Q

what type of cells mature in odontoblasts?

A

Dental papilla cells

56
Q

what type of cells mature into ameloblasts?

A

Inner Enamel Epithelium cells

57
Q

what do odontoblasts form?

A

predentine and dentine

58
Q

what do ameloblasts form?

A

enamel

59
Q

what is the cervical loop?

A

where the outer enamel epithelium cells meet the inner enamel epithelium cells
most cervical part of the enamel organ

60
Q

what is cervical loop proliferation induced by?

A

mesenchymal cells of the dental papilla

61
Q

what are the stages of life as an ameloblast?

A

pre-secretory
secretory
transition
maturation
postmaturation

62
Q

what is pre dentine?

A

the organic matrix that makes up dentine before its calcified

63
Q

what is dentine?

A

mineralised pre-dentine

64
Q

what is enamel?

A

2 groups
amelogenins make up 90-95%
enamelins make up 5-10%

65
Q

what stage does tooth morphogenesis take place?

A

late cap stage/early bell stage

66
Q

where does the signal for tooth shape take place?

A

dental papilla

67
Q

does an incisor or molar require more areas of maturation to take place?

A

molar

68
Q

the only area within the oral cavity where pit x2 is expressed is where?

A

dental epithelium

69
Q

for tooth development to occur what must be switched on?

A

pit x2

70
Q

expression of what drives incisor development?

A

MSX1 and 2

71
Q

expression of what drives molar development?

A

BarX1 and DLX1 and 2

72
Q

What gene determines where teeth form?

A

PITX2

73
Q

What will the reduced enamel epithelium eventually form?

A

junctional epithelium

74
Q

when the succession of the secondary dentition happens what side does the tooth erupt from, labial or lingual?

A

lingual

75
Q

what is it known as a tooth erupts from the secondary dentition on the labial side?

A

tooth gland lamina

76
Q

for anodontia to occur what has happened?

A

something has gone wrong during initiation stage with expression of the genes

77
Q

for supernumerary to occur what has happened?

A

over expression of one of the genes in the initiation stage

78
Q

for microdontia/macrodontia to occur what stage has their been a disruption in?

A

bud stage

79
Q

what dental developmental disturbances can occur in the cap stage?

A

dens in dente
fusion and germination

80
Q

for crown development:
Epithelium -> ameloblasts = ?

A

enamel

81
Q

for crown development:
dental papilla -> odontoblasts = ?

A

dentine

82
Q

for root development:
dental papilla -> odontoblasts = ?

A

dentine

83
Q

for root development:
dental follicle -> cementoblasts = ?

A

cementum

84
Q

what is root development driven by?

A

hertwig’s epitheial root sheath

85
Q

other than hertwig’s epitheial root sheath, what else aids in root formation?

A

dental follicle

86
Q

what are the 3 layers of the dental follicle?

A

inner investing layer
loose connective tissue
outer layer

87
Q

what 3 things make up root structure?

A

root dentine
cementum
periodontal ligament

88
Q

there is a layer of enamel proteins on the dentine layer, what is the purpose of this?

A

allow cementoblasts to attach to start forming the cementum

89
Q

the enamel matrix proteins on the dentine layer form a layer called what?

A

hyaline layer of hopewell smith

90
Q

dental follicle cells receive signals from what to allow them to differentiate into cementoblasts, fibroblasts, osteoblasts etc

A

HERS

91
Q

Dental papilla in response to what signals will start forming root odontoblasts to form root dentine?

A

HERS

92
Q

What does the hyaline layer of hopewell smith start off as?

A

enamel matrix proteins

93
Q

where does the hyaline layer pf hopewell smith lie?

A

between dentine and cementum

94
Q

what is cementogenesis?

A

formation of cementum

95
Q

what are the 2 types of cementum?

A

acellular (primary)
cellular (secondary)

96
Q

what type of cells cause osteogenic differentiation?

A

HERS cells

97
Q

what are the main cell type found in the PDL?

A

Spindle-shaped fibroblasts

98
Q

what is the intermediate plexus?

A

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
Q

what are the 3 stages of dentine formation?

A

cytodifferntiation
matrix formation
mineralisation

100
Q

what are the 2 types of dentine?

A

mantle dentine
circumpulpal dentine

101
Q

what is hydroxyapatite?

A

a form of calcium apatite, also known as calcium phosphate, and is a naturally occurring mineral that makes up our bones and teeth

102
Q

what do hydroxyapatite crystals form?

A

calcospherites

103
Q

what is mantle dentine?

A

very first formed dentine
supports the overlying enamel layer

104
Q

what is circumpulpal dentine?

A

the rest of dentine
formed before root formation is completed

105
Q

what is active tooth eruption?

A

bodily movement of the tooth

106
Q

what is passive eruption?

A

uncovering of the tooth by apical gingival migration

107
Q

what position do successional teeth move from?

A

lingual/palatal position

108
Q

what is intraosseous tooth eruption?

A

involves the formation of root of a tooth which allows the tooth to erupt from the bone

109
Q

what is supraosseous tooth eruption?

A

consists of infragingival eruption and supragingival eruption.

110
Q

what eruption comes first, intraosseous or supraosseous?

A

intraosseous