BDS2 > Dental development > Flashcards

Dental development Flashcards

(149 cards)

Study These Flashcards
1
Q

Who was the first person to research about the idea of growing teeth in a lab?

A

Shirley Glasstone (1938)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 3 primary embryonic layers all body tissues develop from?

A

ectoderm, mesoderm, endoderm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What tissue type is tooth enamel derived from?

A

ectoderm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What tissue type are all parts of the teeth and supporting structures - except enamel - derived from?

A

ectomesenchyme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where does the ectomesenchyme originate from?

A

‘neural crest’ which develops beside the primitive nervous system (ectoderm)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What structures do teeth develop from?

A

tooth germs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the neural crest?

A

a fourth cell type that forms between the ectoderm and the neural tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the neural crest tissue also known as?

A

ectomesenchyme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Where does neural crest tissue migrate towards?

A

towards the developing face and jaws

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What embryonic structures give rise to various anatomical features of the head and neck?

A

branchial arches migrate from dorsal to ventral region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the branchial arches responsible for?

A

formation of number of head and neck tissues including part of the teeth (ectomesenchyme)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What condition results from the failure of ectomesenchyme cells to migrate?

A

mandibulofacial dysostosis (aka Treacher Collins syndrome)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the phenotype features of mandibulofacial dysostosis?

A

greater interpupillary distance, lower ear position, ear malformation, smaller mandible and maxilla compared to facial vault - results in crowding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Outline the stages of tooth development

A

Initiation (dental lamina), morphogenesis (bud), cytodifferentiation (bell), matrix secretion, root formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Name the processes present in a 5-6 week embryo that will form the face

A

maxillary process, stomodaeum, mandibular processes (2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How is the maxilla formed?

A

maxillary process joins with the frontonasal process to form the maxilla

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the stomodaeum?

A

the embryonic precursor to the mouth cavity / lining of oral cavity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How is the mandible produced?

A

joining together of the 2 mandibular processes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the first structure to form in tooth development?

A

primary epithelial band

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the primary epithelial band?

A

thickening in epithelium of embryonic mouth (stomodaeum)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does the oral epithelium thicken to form?

A

primary epithelial band

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

When does the dental lamina form?

A

approx. 7 weeks IUL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How does the dental lamina form?

A

primary epithelial band grows into the jaw and divides into the vestibular lamina and the dental lamina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What two structures does the primary epithelial band divide into (approx week 7)?

A

vestibular lamina and dental lamina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What is the fate of the vestibular lamina?
breaks down via apoptosis to form the buccal sulcus
26
What is the fate of the dental lamina?
enamel organ develops from the dental lamina
27
What shape is the dental lamina?
horse-shoe shaped
28
What are the thickenings that appear along the dental lamina at approx 8 weeks IUL?
tooth germs
29
What stage of tooth development follows initiation?
morphogenesis (shape and form created)
30
What is the first stage of morphogenesis?
'bud' stage of the enamel organ
31
How does the 'bud' stage of the enamel organ form?
the dental lamina thickens into the 'bud' stage enamel organ
32
What structure surrounds the enamel organ?
ectomesenchyme condensation which is the dental papilla
33
What is the dental papilla formed of?
ectomesenchyme cells (condensation)
34
What cells make up the enamel organ?
ectoderm cells
35
What shape rearrangement does the 'bud' stage of the enamel organ undergo?
bud -> cap
36
When does the 'cap' stage form?
at approx 11 weeks IUL the enamel organ forms a 'cap' over the papilla
37
What does the 'cap' stage enamel organ consist of?
external enamel epithelium (EEE) and internal enamel epithelium (IEE)
38
What structure do the external enamel epithelium and the internal enamel epithelium meet at?
cervical loop
39
What is a placode?
thickening of the embryonic ectoderm (epithelium) which forms a bud and eventually an anatomical structure
40
Which tissues involve the formation of a placode and bud stage during their development?
tooth, hair, nail, mammary gland
41
Example of a disease that will affect the teeth and other tissues too
ectodermal dysplasia - affects development of structures derived from the ectoderm (hair, nails, teeth, glands)
42
What is a syndrome?
a disease which has a number of associated phenotypes
43
Why is ectodermal dysplasia considered a syndrome?
affects multiple tissues which are derived from the ectoderm
44
What is hypohidrotic ectodermal dysplasia?
genetic condition (mutation in EDA gene) resulting in missing teeth, reduced sweating and sparse hair in severe forms of the disease
45
What is dysplasia?
abnormal growth / development of cells
46
What term is used to describe the developmental absence of teeth?
hypodontia
47
Why can severe hypohidrotic ectodermal dysplasia result in the absence of hair as well as hypodontia?
hair follicles and teeth are both formed by placodes in the same process
48
What promotor / gene is ectodermal dysplasia associated with?
EDA1
49
How can ectodermal dysplasia be reversed to a normal phenotype?
gene therapy for EDA1 gene (results in teeth forming normally)
50
In a study into gene therapy for ectodermal dysplasia in dogs, what are the 2 controls that an affected treated dog is compared to?
an affected untreated dog (hypodontia) and a normal / unaffected untreated dog
51
What stage of tooth development follows morphogenesis?
cytodifferentiation (cell differentiation into ameloblasts and odontoblasts)
52
What stage is the enamel organ at in cytodifferentiation?
bell stage
53
At what week is the enamel organ at the bell stage?
approx 14 weeks IUL
54
What happens at the 'bell' stage of the enamel organ?
more cell layers are differentiated (cytodifferentiation) and tooth shape is defined
55
Which stage of the enamel organ has 4 cell layers?
'bell' stage
56
What are the 4 cell layers of the 'bell' stage enamel organ?
internal enamel epithelium (IEE), external enamel epithelium (EEE), stratum intermedium, stellate reticulum
57
What cell layer of the 'bell' stage enamel organ can hold energy/materials/sugars necessary for cells to produce the enamel matrix?
stellate reticulum (filled with glycogen - energy for ameloblasts to produce matrix)
58
Why does the stellate reticulum require an energy source?
blood vessels are far away and the enamel organ cannot access energy from the dental papilla as the matrix acts as a barrier that cannot facilitate diffusion
59
Where do odontoblasts get their energy from?
odontoblasts get their energy from the dental papilla in order to form dentine
60
Where do ameloblasts get their energy from?
ameloblasts use glycogen in stellate reticulum as energy for enamel production
61
Where does the process of differentiation begin and move towards?
process of differentiation starts at apical region and moves down towards the cervical loop
62
What processes follow cell differentiation?
matrix formation (dentine then enamel) - follows cell differentiation therefore also starts at apical region and moves towards cervical loop
63
How does the permanent tooth germ develop?
as an extension on the lingual side of the dental lamina which becomes the dental lamina for the permanent successor
64
At approx what week of IUL does the lingual extension of the dental lamina for the permanent successor start to develop?
approx week 12
65
How does the 1st permanent molar germ develop (no deciduous predecessor)?
1st permanent molar germ develops as a backwards extension of the dental lamina
66
At what week does the 1st permanent molar germ develop?
16th week
67
What stage of tooth development follows cytodifferentiation?
matrix secretion
68
What stage is the enamel organ at when matrix secretion begins?
late bell stage enamel organ
69
What week of IUL does matrix secretion begin?
approx week 18
70
What happens during the late bell stage enamel organ?
- crown shape is well defined - apposition of dentine and enamel matrix begins
71
Does the enamel or dentine matrix begin forming first?
dentine matrix first, then enamel matrix (odontoblasts differentiate before ameloblasts)
72
Why is tooth development complex and therefore difficult to reciprocate in the lab?
involves a number of genes / promotors at each stage (e.g. placode formation, transition from bud to late bell stage) and lots of interactions between the dental papilla and enamel organ
73
What cells differentiate into odontoblasts?
dental papilla cells (ectomesenchyme) adjacent to the IEE differentiate into odontoblasts
74
What is the function of odontoblasts?
odontoblasts lay down dentine matrix which is later mineralised
75
Which cells differentiate into ameloblasts?
IEE cells (ectoderm)
76
When do IEE cells differentiate into ameloblasts?
once dentine formation has begun
77
What is the function of ameloblasts?
produce enamel matrix
78
What is the dentine matrix deposited from odontoblasts mainly made up of?
mainly collagen
79
What is the name of the unmineralized dentine secreted from odontoblasts?
predentine
80
What substance mineralises dentine?
hydroxyapatite
81
Which 2 cell groups do dental papilla cells subdivide into?
subdivide to produce odontoblasts (differentiated) and stem cells (remain undifferentiated)
82
What is the role of the stem cells produced from the dental papilla adjacent to the IEE?
stem cells have the ability to differentiate into odontoblasts to produce reparative dentine (tertiary) in the event that odontoblasts are damaged
83
Describe the cell and matrix layers from the inner portion of the tooth to the outer surface
dental papilla, odontoblasts, predentine, dentine, enamel, ameloblasts, enamel organ
84
How mineralised is mature enamel?
very highly mineralised - 96%
85
What two stages is enamel formation made in?
1. protein matrix deposition 2. maturation
86
What is the mineralisation of enamel following the protein matrix deposition?
partially mineralised (30%)
87
What happens during the maturation / second stage of enamel formation?
organic part of the protein matrix is removed and mineralisation is completed (30 -> 96%)
88
Examples of proteins in the enamel matrix that are broken down and absorbed by ameloblasts in the maturation stage
amelogenins and enamelins
89
Outline the 4 main stages of ameloblast differentiation
differentiation, secretion, maturation, regression
90
What ameloblast structure is responsible for the organisation of the enamel crystallites?
Tomes process - crystallites are perpendicular to surface
91
What are all 7 stages of ameloblast differentiation?
1. morphogenic 2. histodifferentiation 3. secretory (initial) 4. secretory (tomes process) 5. maturative (ruffle-ended) 6. maturative (smooth) 7. protective
92
How do the stages of ameloblast differentiation differ as you move cervically?
later stage of differentiation at cusp, earlier stage close to cervical region. Therefore, the stages of enamel formation progress as you move cervically.
93
What happens during ameloblast differentiation (first stage of amelogenesis)?
- dentine induces differentiation of IEE cells into ameloblasts - they elongate, becoming columnar - nucleus migrates to basal end of cell (away from ADJ)
94
What happens during the secretory phase of amelogenesis (stage 2)?
- ameloblasts synthesis and secrete enamel matrix proteins (amelogenins) - matrix is partially mineralised (30% as seeded crystallites)
95
What happens during the maturation phase of amelogenesis (stage 3)?
- most of the matrix proteins are removed - mineral content of enamel increased - 96% mineralised
96
What happens during the protection phase of amelogenesis (4)?
ameloblasts regress to form a protective layer - the reduced enamel epithelium
97
What is the name of the protective layer that ameloblasts form once they regress?
reduced enamel epithelium
98
What the role of the reduced enamel epithelium?
- protect tooth prior to eruption and the REE is involved in eruption - forms the junctional epithelium (important for attachment
99
What type of inheritance pattern is hypoplastic hypomaturation amelogenesis imperfecta?
autosomal recessive
100
What gene is impaired in hypoplastic hypomaturation amelogenesis imperfecta?
matrix metallopeptidase 20 gene, (MMP20)
101
Where is the matrix metallopeptidase 20 gene (MMP20) located?
long arm (q) of chromosome 11 at position 22.3
102
What is the role of the MMP20 gene?
encodes for / provides instructions for making enamelysin
103
What is the role of enamelysin?
cleaves other proteins such as amelogenin, ameloblastin and enamelin into smaller pieces which are easier to remove
104
Example phenotype of amelogenesis imperfecta
dull and rough enamel appearance (due to low mineralisation), increased caries risk, frail, easily fractured
105
What is the radiographic appearance of amelogenesis imperfecta?
difficult to differentiate between enamel and dentine (low mineral content of enamel is similar to dentine's mineral content)
106
Why may it be difficult to identify amelogenesis imperfecta in a family history?
there are a range of phenotypes from mild to severe (range of mineral content loss)
107
How can you differentiate between fluorosis and amelogenesis imperfecta?
radiograph - mineral content is increased in fluorosis and lost in AI
108
What is dentinogenesis imperfecta?
dentine is not mineralised to the level it should be
109
Why is tooth wear severe in dentinogenesis imperfecta?
dentine is not mineralised enough to provide cushioning to enamel
110
What is the best way to differentiate dentinogenesis imperfecta and amelogenesis imperfecta?
radiograph
111
What is the radiographic presentation of dentinogenesis imperfecta?
enamel can be seen but pulp chambers cannot be identified (except RCT)
112
Why can pulp chambers not be identified on a radiograph of a patient with dentinogenesis imperfecta?
dentine has a much lower mineral content than normal so it cannot be differentiated from pulpal tissue
113
What is the final stage of tooth development that follows matrix secretion?
root formation
114
When does root formation begin?
once crown formation is completed
115
What defines the root shape?
the apical growth of the cervical loop (now called Hertwig's epithelial root sheath)
116
What is the cervical loop called in root formation?
Hertwig's epithelial root sheath
117
What layers make up Hertwig's epithelial root sheath?
IEE and EEE - 2 layers as opposed to the 4-layered enamel organ
118
What induces odontoblasts to form root dentine?
Hertwig's epithelial root sheath (HERS)
119
What happens once the initial layer of root dentine is formed?
Hertwig's root sheath breaks up (no enamel in root) into remains (cell rests / debris of Malassez)
120
What do the remains of Hertwig's epithelial root sheath cells persist as?
cell rests / debris of Malassez - which may develop into a cyst
121
What cell remains are capable of developing into odontogenic cysts?
cell rests / debris of Malassez (associated with odontogenesis)
122
How do cementoblasts arise?
as HERS breaks down, the mesenchymal cells from the follicle contact the dentine and differentiate into cementoblasts
123
What is the role of cementoblasts?
form cementum
124
What structures are embedded into the cementum?
fibres from the developing PDL are embedded into the cementum
125
What is the name of the PDL fibres embedded into cementum?
Sharpey's fibres
126
Outline a summary of root formation
1. Cervical loop / HERS migrates downwards providing the root shape 2. Induces odontoblasts to form dentine 3. HERS breaks down as soon as dentine is formed 4. remains of HERS cells = cell rests / debris of Malassez 5. HERS breakdown allows mesenchyme follicle cells to contact dentine 6. follicle cells differentiate into cementoblasts 7. produce cementum
127
What is the dental follicle?
mesenchymal cells and fibres that encase the enamel organ and dental papilla
128
What are the 3 components of a tooth germ?
dental follicle, enamel organ, dental papilla
129
What type of tissue is the enamel organ made from?
epithelium
130
What type of tissue forms the dental papilla?
ectomesenchyme
131
What type of tissue forms the dental follicle?
ectomesenchyme (?)
132
Where does the enamel organ originate from?
ectoderm
133
Where does the dental papilla originate from?
neural crest
134
Where does the dental follicle originate from?
neural crest
135
What does the enamel organ form?
enamel
136
What does the dental papilla form?
dentine and pulp
137
What does the dental follicle form?
cementum, PDL, part of alveolar bone
138
How can teeth developmental abnormalities be categorised?
prenatal, postnatal, inherited (genetic), acquired
139
Example of an acquired tooth developmental abnormality
tetracycline (antibiotic) can stain teeth during tooth formation resulting in a line across the teeth
140
What features of teeth can be affected by teeth developmental abnormalities?
number, shape, size, structure, eruption
141
Example of teeth developmental abnormalities that affects the number of teeth
hypodontia, ectodermal dysplasia
142
Example of a teeth developmental abnormality that can affect tooth eruption
ectodermal dysplasia can delay eruption
143
Possible cause of an acquired enamel defect
infection e.g. measles - results in a line of tooth defect at stage of tooth development when infection occurred (e.g. incisal area formed but not cervical area yet)
144
What is gemination?
a tooth that has divided into 2 resulting in 2 teeth joined together (e.g. gemination of lateral - 2 laterals from one tooth, central and canine still present)
145
What is fusion?
two teeth joining together (e.g. lateral joins with central incisor) resulting in hypodontia (of lateral, in this case)
146
What is a paramolar?
a supernumerary molar (4th molar)
147
What may be an alternative explanation for gemination of a third molar?
fusion of 3rd molar with a paramolar / 4th molar
148
What may a radiopaque apex on a radiograph suggest?
unusual root orientation / more roots than expected - take another radiograph at a different angle to see more clearly
149
What is concrescence?
teeth fused by cementum (other tooth could be embedded in bone and not visible without a radiograph)
BDS2
flashcards
Decks in class (80)
# Cards
Brainscape helps you reach your goals faster, through stronger study habits.
© 2026 Bold Learning Solutions. Terms and Conditions