Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Integration finals > tooth development > Flashcards

tooth development Flashcards

1
Q

Ectoderm lining stomodeum gives rise to oral epithelium

on the

A

1st branchial arch.

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

when is primary epithelial band formed

A

6th week of prenatal development

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

Primary epithelial band origin

A

oral epithelium

thickens and invaginate into the ectomesenchyme

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

Primary epithelial band

A

These bands are roughly
horseshoe shaped and
correspond to the future dental
arches of the upper & lower jaws

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

what happen by the 7th week

A

primary epithelial band
will divide to form:
(1) vestibular lamina
(2) dental lamina

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

Vestibular lamina

A

form vestibule

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

Vestibular lamina process

A

Cells of the vestibular lamina will proliferate,
and then the central epithelial cells
degenerate to form the sulcus of the vestibule
between the cheek and the tooth bearing
area.

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

Dental lamina

A

-Dental lamina contributes to the development of teeth.
• Dental lamina is not a strand but a sheet.
• Is divided into General lamina & Lateral lamina

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

dentall lamina process

A

Within the dental lamina continued & localized proliferative
activity leads to the formation of a series of epithelial
outgrowths into the ectomesenchyme,
the outgrowth occurs at sites corresponding to future deciduous teeth

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

What controls the initiation of tooth

development?

A

earliest msenchymal markers = Lhx 6 & 7 (expressed at ncc)
lhx induced by fgf8
fgf expressed at 1st branchial arch

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

What controls the position & number of tooth

germs?

A

pax 9 - define location of tooth germs

fgf8 induce pax 9

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

TOOTH TYPE DETERMINATION

A

PATTERNING , homodont and heterodont

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

Hypothetical Models Explaining How Different

Tooth Shapes Are Determined

A

field model and clone model

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

field model

A 
Genes responsible for tooth
shape reside within the
ectomesenchyme in distinct
BUT graded fields for each
tooth family.
Each of the fields express differing patterning homeobox
genes.
However, genes in the oral epithelium provides the
signalling.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

clone model

A

Each tooth class is derived from a clone of
ectomesenchymal cells programmes by
epithelium to produce tooth of a given pattern.
A: The molar clone has induced the dental lamina to begin tooth development. At its
posterior border the clone and dental lamina grow posteriorly by means of the
progress zone.
B: When a clone reaches the critical size, a tooth bud is initiated at its center.
C: The next tooth bud is initiated until the progress zone of the clone has escaped
its influence

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

when is bud stage

A

8th week of prenatal development

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

what happen during bud stage

A 
A series of epithelial
outgrowth develops on the
surface of the dental lamina..
Forming tooth bud
maxillary arch : 10 buds
mandibular arch : 10 buds
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

when is early cap stage

A

Forming tooth bud
maxillary arch : 10 buds
mandibular arch : 10 buds

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

what happen during early cap stage (1)

A

Each of the tooth buds
Will invaginate into the
ectomesenchyme to form a capshaped structure.
tooth germ

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

what happen during early cap stage (2)

A

Nerve fibres & blood vessels are NOT present
in the enamel organ at any time.
• Blood vessels enters the dental papilla during
cap stage.
• Blood vessels are also found around the tooth
germ in the dental follicle

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

tooth germ

A

enamel organ, dental papilla, dental follicle

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

late cap stage

A 
histodifferentiation
Epithelial cells in the enamel organ will
differentiate to form Stellate reticulum
(SR) during late cap stage.
However, the development of SR will
continues until early bell stage
formation of transitory structures.
formation of permanent dentition
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

stellate reticulum

A

Cells in the center of the enamel organ synthesize &
secrete glycosaminoglycans into the extracellular
components between the epithelial cells
Glycosaminoglycans are hydrophilic, and so pull
water into the enamel organ
Volume of the extracellular compartment of the enamel
organ increases, forcing the central cells to separate.
The cells retained connections through desmosomal
contacts, and thus become star shape & is termed
Stellate Reticulum (SR)

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

TRANSITORY STRUCTURES

A
  • Enamel knot
  • Enamel cord
  • Enamel niche
  • Enamel navel
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

enamel knot

A 
- Is a localised mass of
cells in the centre of
the enamel organ
- visible in sections of
molar cap stage tooth
germs.
26
Q

Enamel cord

A

Enamel knot which
extends between
the IEE & EEE

27
Q

Enamel navel

A

A small invagination
situated at the EEE
where the enamel cord
terminates.

28
Q

Enamel niche

A

It is seen where the tooth germ appears to have a double
attachment on the dental lamina.
The enamel niche area contains connective tissue.

29
Q

when is formation of permanent dentition

A

At the 10th wk of prenatal development

during the late cap stage for each primary dentition

30
Q

formation of permanent dentition

A

Tooth bud for permanent dentition forms on the

lingual of the deciduous tooth germ

31
Q

Succedaneous

A

Permanent teeth formed with primary predecessors.
- include anterior teeth & premolars
- replace primary anterior teeth & molars, respectively.
- permanent succedaneous tooth crown will erupt
lingual to its primary predecessors root

32
Q

Nonsuccedaneous

A
  • Permanent molars.
  • Have no primary predecessors.
  • Develop from a posterior extension of the dental lamina.
    (distal to the primary second molar’s dental lamina)
33
Q

when is early bell stage

A

11th – 12th wk of prenatal development

34
Q

early bell stage

A 
Enamel organ resembles a
bell as the undersurface of
the epithelial cap deepens.
During this stage, the
tooth crown assumes its
final SHAPE
(morphodifferentiation).
breakup of dental lamina
crown pattern determination
35
Q

morphodifferentation in early bell stage

A

cells in enamel organ into :

eee,iee, sr, si

36
Q

iee

A 
is having
columnar cell
shape.
- is adjacent to SI
(IEE is connected
to SI by desmosomes
& gap junction)
- will differentiate
into ameloblasts
37
Q

eee

A 
- are the outer
cuboidal cells
of the enamel
organ.
- will serve as
a protective
barrier for
the rest of
the enamel
organ during
enamel
production.
38
Q

si

A 
- consists of 2
or 3 layers of
flattened cells
lying over the
IEE
- SI helps to
support the
production of
enamel.
39
Q

sr

A 
- are star-shaped
cells, forming a
network.
- cells are
connected to
one another by
desmosomes.
- SR helps to
support the
production of
enamel
40
Q

Break Up of the Dental Lamina

A 
Epithelial cells of the dental lamina
undergo lysis
Dental lamina disappears
The developing tooth & the oral
epithelium is separated
41
Q

Crown Pattern Determination

A

The intrinsic growth by differential rates of
mitotic division within IEE.
Resulted in the folding of the IEE
The point at which IEE cell differentiation 1st occurs
represents the site of future cusp development
The occurrence of a 2nd zone of cell differentiation within
the IEE leads to the formation of a 2nd cusp.

42
Q

when BELL STAGE (late)

A

13th -18th wk of prenatal development

43
Q

BELL STAGE (late)

A 
Is associated
with the
formation of
the hard
tissues :
• Dentin
• Enamel
ree
root formattion
44
Q

BELL STAGE (late) process

A 
(1)Ectomesenchymal cells of the
dental papilla facing IEE will
differentiate into odontoblasts
to form dentin (dentinogenesis).
(2) The increase in size of the
papillary cells eliminates the
acellular zone (basement
membrane) between
odontoblasts and IEE.
(3) The columnar cells of IEE facing the
odontoblasts will then differentiate into
ameloblasts to form enamel (amelogenesis)
45
Q

Odontoblasts :

A
  • will deposit organic matrix of dentin.

- will then move towards the center of dental papilla.

46
Q

Ameloblasts

A
  • will secrete organic matrix against the newly formed
    dentinal surface (mantel dentin).
  • will then move away from the dentin, giving the
    thickness to the enamel
47
Q

nutrient suppy of late bell stage

A
  • will secrete organic matrix against the newly formed
    dentinal surface (mantel dentin).
  • will then move away from the dentin, giving the
    thickness to the enamel
    When dentin is formed:
    -It cuts off the nutrient sources from the blood vessels of the
    dental papilla.
    -Causing a drastic reduction of nutrients reaching the
    enamel organ (occurs when the cells of the IEE are about
    to secrete enamel, and thus, the demand for nutrients
    increases)
48
Q

demand of nutrient supply satisfied by (late bell)

A

(i) the collapse of SR
(ii) Invagination of EEE by blood vessels
lying outside the enamel organ

49
Q

ree what

A

Also known as reduced dental epithelium.

Overlies a developing tooth.

50
Q

ree formed by

A

(1) a layer of ameloblasts
(differentiated IEE)
(2) the adjacent layer to IEE
(SI, SR, EEE)

51
Q

As REE degenerate

A

the tooth is revealed by

erupting into the oral cavity.

52
Q

root formation

A

when crown is completed, process of root formation will start. and when 1/3 root formed, tooth erupt

53
Q

component for root formation

A

cervical loop, hers

54
Q

cervical loop

A 
Cervical loop (CL) is
responsible for root
development.
CL is the most cervical
portion of the enamel organ.
CL consist of only IEE and
EEE.
Cervical Loop
Epithelial cells of the cervical loops will proliferate &
forms a double layer of cells known as Hertwig’s
Epithelial Root Sheath (HERS)
55
Q

fx of hers

A
  • to determine the shape of the root.
  • to determine the number of roots.
  • to induce the formation of root dentine.
56
Q

hers

A 
HERS induce the outer cells of dental
papilla (cells facing the HERS) to
undergo differentiation & form
odontoblasts.
The odontoblasts will then undergo
dentinogenesis and begin to secrete
predentin.
HERS will extend downwards & the
tip of HERS will bend slightly to form
epithelial diaphragm enclosing
dental papilla, except for an opening
at base (primary apical foramen).
When root dentin formation is
completed, HERS will disintegrate &
the cells may become the epithelial
cell rests of Malassez (located in the
periodontal ligament area).
Some epithelial cell rests of
Malassez may become calcified in
the periodontal ligament, and known
as cementicles
57
Q

multirooted tooth

A

horizontal ‘tonguelike’ epithelial extensions occurs within the
root trunk
The single cervical opening (primary apical foramen) will be
divided into 2 or 3 openings at the bifurcation or trifurcation of
the root by these horizontal extensions

58
Q

disturbances during root development

A

accessory root canal, enamel pearl, dilaceration, supernumerarry roots

59
Q

Accessory Root Canal

A 
• occurs due to a break in the
continuation of the HERS, eg.:
(i) HERS encircles a blood vessel
(ii) lack of fusion of the epithelial
diaphragms.
 causes no deposition of dentine
 is usually at the apical 1/3 of the root.
60
Q

Enamel Pearl

A

Is a small spherical enamel formed on the root surface.
Caused by HERS which accidentally contained
SI & SR
Induce the formation of ameloblasts at the root area

61
Q

Dilaceration

A 
• is due to distortion of HERS caused
by injury or pressure during root
development
• causes root (or roots) to be distorted
• can occur in any tooth or group of
teeth
Assoc Prof Dr Wan Himratul Aznita Wan Harun
Dilaceration
• can cause problems during extraction and
endodontic treatment.
62
Q

Supernumerary Roots (accessory root)

A

occurrence could be due to trauma, pressure or
metabolic disease that affects HERS
could occur in any teeth, but mainly in the
permanent 3rd molars (occurrence are rare in the
incisors).
can cause problems during tooth extraction and
endodontic treatment.

Integration finals (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions