Tooth Development- Dr. Bumann (FINAL) Flashcards
First sign of tooth development is at:
6-7 weeks IU
Deciduous teeth begin to calcify at:
13-20 weeks IU
By ___ week in utero, all deciduous teeth have begun to calcify
18-20 weeks
Deciduous teeth erupt at:
6-30 months
The first part of the tooth to calcify:
crown
What aspect of tooth development occurs in the dental lamina?
initiation
What aspect of tooth development occurs in the bud stage?
morphogenesis
What aspect of tooth development continues from bud stage to cap stage?
morphogenesis
The process of morphogenesis occurs during what stages of tooth development?
bud & cap stage
What aspect of tooth development occurs during the bell stage?
cell differentiation
What aspect of tooth development occurs during the eruption stage?
matrix secretion
What is the most important part of tooth formation?
cross-talk between epithelium and mesenchyme
Signals of tooth development originate from the:
oral ectoderm
signals that originate from the oral ectoderm cause:
the dental mesenchyme to start signaling
List the stages of tooth development that contribute to crown formation:
- initiation
- bud stage
- cap stage
- bell stage
- enamel and dentin formation
The three main categories of tooth formation include:
- crown formation
- root formation
- supporting structures
Initiation of tooth formation involves the:
dental placode
What plays an important role in getting the mesenchyme that is going to form the teeth into the proper location?
neural crest mesenchyme
Where do the majority of our teeth originate?
through the first pharyngeal arch where two parts of the maxillary and mandibular processes are
What epithelium epithelium is located between the maxillary and mandibular processes?
odontogenic epithelium
List the processes involved in the developing human head:
- frontonasal process
- medial nasal process
- lateral nasal process
- maxillary process
- mandibular process
Where do the four maxillary incisors originate from?
the medial nasal process
What is the shape of the primary epithelial band?
horse shoe
The primary epithelial band corresponds to:
future dental arches
The primary epithelial band gives rise to:
- dental lamina
- vestibular lamina
In tooth development, its the ___ of gene expression that helps to define regions
patterning
What two genes are important in presumptive incisor region?
BMP4 and Islet-1
What are two genes target the presumptive molar region?
FGF8 and FGF9
____ is expressed in the epithelium and ____ is expressed in the mesenchyme where the tooth bud would form
Shh; Pax9
Mice have ___ lower incisors and ___ upper incisors, and ____ molars, none of which are ___.
2;2;3; succedaneous
What really is the initiation of tooth development?
the dental lamina formation
In the process of dental lamina formation, ___ formation results from epithelial thickening
placode
In the process of dental lamina formation, what do we see happen to the epithelium?
epithelial outgrowth into the mesenchyme
In the process of dental lamina formation, initial odontogenic potential lies in the epithelium but subsequently shifts to:
mesenchyme
In the process of dental lamina formation, what induces the oral ectoderm to become the dental lamina?
neural crest mesenchyme
In the process of dental lamina formation, the neural crest mesenchyme induces the ___ to become the ____.
oral ectoderm –> dental lamina
What develops after dental lamina formation?
dental and vestibular lamina formation
The vestibular lamina will form the:
vestibule
The vestibular lamina is separated from the surrounding mesenchyme by a:
basement membrane
After initiation of tooth development comes the ___ stage
bud stage
During the bud stage of tooth development, epithelial cells show:
no major changes
During the bud stage of tooth development, what are the different signaling molecules involved in placode formation?
Shh, Lef-1, & Eda-Edar
What does placode formation mean and what stage does it take place in?
ectoderm thickening; bud stage of tooth development
During the bud stage of tooth development, what happens to the mesenchyme and why does this happen?
mesenchyme beneath starts to condense; by factors secreted by epithelium
During the bud stage of tooth development, we have cross-talk between:
epithelium and mesenchyme
During the bud stage of tooth development, ____ potential in the epithelium
odontogenic
tooth number is determined during:
initiation
tooth size and shape are determined during:
morphogenesis
tooth tissues and mineralization occurs during:
differentiation
Bud stage is extremely important determining:
tooth size & shape
The primary enamel knot is formed during:
the cap stage
The stage of tooth development in which the epithelium penetrates the mesenchyme and continues to condense:
cap stage
What happens to the epithelium during the cap stage?
proliferation
In the cap stage, when the epithelium continues to proliferate, the mesenchyme continues to:
condense
During the cap stage, the tooth germ is composed of:
enamel organ & dental papilla
The enamel organ is the:
enamel of the tooth
Enamel is formed by ___ which is coming from the ___ and NOT the ____.
ameloblast; epithelium; not neural crest derived
During the cap stage, the dental papilla on the outside forms the ___, while the dental papilla on the inner side forms the ____.
dentin; pulp
During the cap stage, what aggregates to form the dental papilla?
ectomesenchymal cells
The bud to cap stage transition is regulated by:
signaling molecules and transcription factors
During the cap stage, following the early cap stage, next the is the:
enamel knot formation
During the cap stage, forms some of the supporting structures such as cementum, periodontium, and alveolar bone proper
dental follicle or dental sac
During the cap stage, the dental follicle or dental sac forms some of the supporting structures such as:
- cementum
- periodontium
- alveolar bone proper
During the cap stage, the key signaling center that consists of cluster of non-dividing cells and determines cusp formation
enamel knot
What stage is the enamel knot formed?
during the cap stage
The enamel knot is a ___ that consists of ___ cells that determine ___.
key signaling center; cluster of non-dividing cells; cusp formation
There is both ___ & ___ enamel knots
primary & secondary
What is the third part of the cap stage of tooth development (following enamel knot formation)
Cap Stage Histodifferentiation
When cells in the enamel organ synthesize glycosaminoglycans in the ECM
Cap Stage Histodifferentiation
During Cap stage histodifferentiation, cells in the enamel organ synthesize:
glycosaminoglycans
During Cap stage histodifferentiation, cells in the enamel organ synthesize glycosaminoglycans into the ECM and this make these cells:
hydrophilic and pull water into the enamel organ
During Cap stage histodifferentiation, the increase in fluid volume force the cells apart leading to the formation of:
star-shaped stellate reticulum cells
During Cap stage histodifferentiation, what is the purpose of the star-shaped stellate reticulum cells?
helps to form the shape of the tooth
During Cap stage histodifferentiation, enamel organ epithelial cells start to separate out into:
- Inner enamel epithelium (IEE)
- Outer enamel epithelium (OEE)
An important regulator of tooth number (during cap stage):
SPRY-2
In a study in which the SPRY-2 regulator was knocked out in mice, what occurred and why?
additional tooth in diastema region; because SPRY-2 normally blocks the signaling of Shh
So when you knock it out, that regulation is no longer there
Name 3 characteristic components of the bell stage of tooth development:
- secondary enamel knot
- amelobasts
- odontoblasts
In the early bell stage:
- Under surface of the epithelium ___ and resembles a ___
- _____ formation
- ___ attains full size and shape
- deepens; bell
- stratum intermedium
- crown
Where are the succedaneous teeth formed from?
permanent tooth bud/ successional lamina
Permanent forms ___ to the deciduous dentition
lingual
Looking at gene expression, we have a higher level of gene expression of _____ as you move towards the:
BMP4 & Msx1; buccal /cheek
On the ____ side of the mice you have inhibition of signaling of BMP4 & Msx1 by ____.
lingual; Osr2
Osr2 is an important regulator of:
succedaneous tooth formation
What are the two processes that occur during the early bell stage of tooth development?
- morphodifferentiation
- cervical loop formation
In the early bell stage, low cuboidal shaped cells are forming in the:
OEE
In the early bell stage, short columnar shaped cells are forming in the ___ & will differentiate into:
IEE; ameloblasts
In the early bell stage, the junction of the IEE and OEE is called ___ and is the future site of ___.
cervical loop (CL); CEJ
In the late bell stage, what happens to the dental lamina?
dental lamina breaks and separates tooth from oral epithelium
In the late bell stage, the IEE completes folding and forms the:
future crown pattern
In the late bell stage, the folding of IEE is due to:
differential rates of mitotic division in IEE
In the late bell stage, under the influence IEE, mesenchymal cells differentiate into ___ that makes ___
odontoblasts; dentin
In the late bell stage, after the mesenchymal cells differentiate into odontoblasts (under influence of IEE) and make dentin the IEE:
Differentiates into ameloblasts and makes enamel
What differentiates into ameloblasts to make enamel?
IEE
In the late bell stage, the site at which IEE differentiates determines:
future cusp formation
Following the bell stage, what processes occur?
enamel, dentin, and pulp formation
Enamel formation may also be called:
amelogenesis
What are the stages of amelogenesis?
- morphogenetic stage
- histodifferentiation stage
- initial secretory stage (NO TOMES PROCESS)
- secretory stage (TOMES PROCESS)
- ruffle ended ameloblast of the maturation stage
- smooth ended ameloblast of the maturation stage
- protective stage
What stage of amelogenesis is the most active laying down of enamel?
secretory stage with tomes process
Are tomes processes involved ion the initial secretory stage of amelogenesis?
NO
We see intense synthetic and secretory activity in the ___ stage of amelogenesis
secretory stage
During the secretory stage of amelogenesis, we have formation of:
enamel rod and inter-rod
During amelogenesis, the ameloblasts secrete granules on the newly formed:
mantle dentin
The most outer layer of laid down dentin:
mantle dentin
Secretory proteins involved in amelogenesis include:
amelogenin; ameloblastin; enamelin
The proteases involved in amelogenesis include:
Enamelysin (MMP20) & Kallikrein
During enamel formation this structure is involved in the orientation of enamel:
striae of retzius
What type of cells makes dentin?
odontoblasts
What type of cells differentiate into odontoblasts to make dentin?
mesenchymal cells
First layer of dentin formed by newly differentiated odontoblasts, hypo mineralized, and only in the crown of the tooth (30-50 micrometers thick)
mantle dentin
Dentin formed during tooth development (4 micrometers per day)
primary dentin
Dentin formed after tooth eruption (0.4 micrometers per day)
secondary dentin
Dentin produced in response to injury to protect the pulp: (cariogenic or trauma)
tertiary dentin
holds the odontoblast together and shoots out their odontogenic processes into the dentin:
junctional apparatus/ complex
TAKE HOME:
We have pre-odontoblasts that differentiate into ____ & these start to lay down ___.
odontoblasts; dentin
TAKE HOME: Over the initial layer of dentin, laid down by odontoblasts we have breakdown of the _____.
basement membrane
TAKE HOME: The breakdown of the basement membrane (over the initial layer of dentin), is where we see ___ go to ___.
pre-ameloblast; pre-secretory ameloblast
TAKE HOME: The pre-secretory ameloblast in combination with the dentin turn into ___ and the ___ can be laid down.
secretory ameloblast; enamel
What happens first? Root development or crown calcification?
crown calcification
In root formation, the IEE and OEE form the cervical loop and proliferate downward to form a double layered structure called ___, also the site of ___
Hertwig’s epithelial root sheath; CEJ
In root formation, ____ differentiate, and ___ forms
odontoblasts; dentin
The completion of root formation occurs as it grows apically down towards the:
alveolar bone
Unlike bone, cementum lacks:
blood & nerve supply
During cementum formation, fragmentation of ___ causing it to be mostly removed before the cementum is laid down.
Hertwig’s Epithelial Root Sheath (HERS)
During cementum formation, differentiation of what occurs?
cementoblasts
During cementum formation, remnants of HERS are called:
epithelial rests of malassez
Cementum may be ___ or ___
acellular or cellular
The type of cementum that seems to very lightly line the outside of the root:
acellular
The type of cementum that is found at the apex & towards the bottom of the root:
cellular
In individuals that have a larger gap between their cementum and enamel (some peoples do not have gap at all, some even overlap), ____ are exposed and these patients will often complain of ___.
odontoblast processes; sensitivity
