Odontogenesis Flashcards
What are the four epithelial stages of Odontogenesis?
dental lamina
bud
cap
bell
In the tooth germ stage, odontogenic ___ and ___ tissues combine to form cell of dentin, enamel, cementum, and pulp.
epithelial; mesenchymal
During the 6th embryonic week, what two epithelial invaginations appear in the lower anterior region of the lower jaw an the upper jaw?
vestibular lamina
primary dental lamina
The vestibular lamina and the primary dental lamina descend into the underlying mesenchymal tissue (___) and continue posteriorly within the mesenchyme as continuous epithelial bands.
ectomesenchyme
The facial band is called ___ ___ and the lingual band is called ___ ___.
vestibular lamina; primary dental lamina
In the vestibular lamina, cell ___ will occur in the center leaving a space known as the ___.
death; vestibule
Cells arising from the dental laminae (primary and secondary) become the odontogenic ___ part of the tooth ___.
epithelial; germ
Cells at the ___ (shallow/deep) end of the dental lamina, where a ___ is destined to form, will develop into epithelial knobs known as ___ ___.
deep; tooth; epithelial buds
T/F. Each epithelial bud is surrounded by mesenchymal tissue.
True.
The primary buds from within weeks ___ to ___ in utero. The central incisors form at week ___ and the second ___ form at week 8.
6; 8; 6; molars
The permanent buds form from ___ months in utero to ___ years postnatally. The first ___ start to develop at 4 months and the central incisors at ___ month in utero. The second and third molars develop ___ months and ___ years postnatally.
4; 5; molar; 5; 10; 5
A total of ___ epithelial buds arise from the primary dental lamina of each arch; ___ primary teeth and ___ permanent molars.
16; 10; 6
Each ___ tooth has its own secondary dental lamina that arises from the ___ side of the primary dental lamina.
succedaneous; lingual
A condensation of ___ is associated with the epithelial cap.
ectomesenchyme
The site of the ___ ___ is a concentration of epithelial cells of the cap that acts as as ___ center and determines if the tooth will develop into an anterior or posterior tooth.
enamel knot; signaling
T/F. The epithelial bell undergoes growth and develops into a cap shaped epithelial structure called an enamel organ.
False, The epithelial CAP undergoes growth and develops into a BELL shaped epithelial structure called an enamel organ.
At the bell stage, what is arranged into 4 distinct cell layers?
the epithelium
The secondary dental lamina is ___ to the primary tooth germ.
lingual
How many secondary lamina arise in each arch?
Ten, one for each secondary tooth
The secondary dental lamina arises from the ___ ___ ___ not the ___ epithelium.
primary dental lamina; oral
What are the three distinct parts of the tooth germ?
- enamel organ
- dental papilla
- dental follicle
T/F. The enamel organ and dental papilla consist of epithelium and the dental follicle contains mesenchyme (ectomesenchyme).
False, the enamel organ ONLY consist of epithelium and the dental follicle AND dental papilla contains mesenchyme (ectomesenchyme).
What part of the tooth germ is avascular? vascular?
avascular - enamel organ
vascualr - dental papilla and follicle
What do inner epithelial cell differentiate into?
ameloblasts - specialized epithelial cells
After the formation of enamel is complete, the ameloblasts, along with other layers of the enamel organ come together over the surface of the enamel as a ___ structure called the ___ ___ epithelium.
protective; reduced enamel
The dental ___ has undifferentiated cells (stem cells) that become odontoblast, ___ and reserve cells.
papilla; fibroblast
What part of the tooth germ ultimately becomes the pulp tissue of the tooth?
dental papilla
Which part of the tooth germ has stem cells that become cementoblast, fibroblast, osteoblast, and reserve cells?
dental follicle
The dental follicle ultimately becomes the ___ ___ of the periodontium.
periodontal ligament
What structure attaches the enamel organ to both mesenchymal parts of the tooth germ?
basal lamina
T/F. Ameloblast appear as columnar epithelial cells.
True.
The light, ___ layer between odontoblasts and ameloblasts is the site of the future ___ junction.
acellular; dentinoenamel
The ameloblast start near the dentin and move outward toward the ___ ___ epithelial layer.
stratum intermedium
What are the four distinct epithelial cell layers of the enamel organ?
- inner epithelial layer
- stratum intermedium epithelial layer
- stellate reticulum epithelial layer
- outer epithelial layer
What is the role of the reduced enamel epithelium?
it protects the enamel from surrounding connective tissue until the tooth enters the oral cavity.
What is the rim of the epithelial bell (enamel organ) where the inner and outer cell layers merge called?
cervical loop
When the inner and outer cell layers come together at the cervical loop it forms a ___ epithelial layer called the ___ ___ ___ ___.
double; Hertwig’s epithelial root sheath
What are the two main funcitons of the Hertwig’s epitheal root sheath?
- determines root dentin outline
2. determines number of root canals of tooth
