Chapter 6-1 Tooth development and Eruption Flashcards
Define odontogenesis
Process of tooth development
What are the stages of tooth development (time frame)
- Initiation: 6 - 7th week
- Bud: 8th week
- Cap: 9thweek
- Bell: 12th week
- Apposition: varies
- Maturation: varies
What are the main processes in each stage
- Initiation: Induction
- Bud: Proliferation
- Cap: Proliferation, differentiation, morphogenesis
- Bell: Proliferation, differentiation, morphogenesis
- Apposition: Induction, proliferation
- Maturation: maturation
When does odontogenesis of primary dentition occur
6th and 7th week
What occurs in the apposition stage?
Formation of partially mineralized dental tissue types, such as enamel, dentin, cementum (the hard tooth tissue)
What occurs during maturation
Structures go through continued mineralization
Induction
Active interaction between embryologic tissue types
At the beginning of 6th week what occurs?
The embryo’s stomodeum is lined by ectoderm
What does the outerpart of the ectoderm give rise to
oral epithelium
How is the dental lamina formed
When oral epithelium grows deeper into the ectomesenchyme
In what direction does the dental lamina grow
Starts in midline and progresses posteriorly
What happens in the bud stage
- extensive proliferation of dental lamina into buds which penetrate the ectomesenchyme
- Proliferation of ectomesenchyme
What does the cap stage involve
Proliferation and differentiation to form tooth germ and primordium of primary tooth
What does the tooth germ consist of?
Enamel organ, dental papilla, dental sac
What is the predominant process in cap stage
morphogenesis
How is the dental papilla formed
ectomesenchyme in the concavity of the cap condenses into a mass
What does the dental papilla give rise to
Dentin and pulp
What is the dental sac/dental follicle?
remaining ectomesenchyme that surrounds the outside of the cap of enamel organ
What does the dental sac produce
Periodontium
Supporting tissue types of the tooth
Cementum
Periodontal ligament
Alveolar process
Tooth germ consist of:
Enamel organ
Dental papilla
Dental sac
What does the enamel organ…
Arise from?
Origin?
Give rise to?
Description
Arises from oral ectoderm and dental lamina
Epithelial origin
Gives rise to enamel
Develops different layers during cap and bell stages of development
What does Dental Papilla…
Arise from?
Origin
Give rise to?
Description
Arises from ectomesenchyme
Connective tissue origin
Forms dentin and pulp
A condensed zone of cells beneath enamel organ and separated from by a basement membrane
What does the Dental sac (Follicle)…
Arise from?
Origin
Give rise to?
Description
Arises from ectomesenchyme
Connective tissue origin
Form cementum, periodontal ligament, alveolar bone
Fibrous tissue
What are the 4 cell types that occur during bell stage
Outer enamel epithelium
Stellate reticulum
Stratum intermedium
Inner enamel epithelium
What cells make up the outer enamel epithelium?
Cuboidal cells of enamel organ
What cells makes up the inner enamel epithelium?
Tall Columnar cells
What type of cells is the stellate reticulum
start shaped cells
What type of cells is the stratum intermedium
compressed flat to cuboidal cells
What are the 2 layers of dental papilla histodifferentiation
- outer cells of dental papilla
- Central cells of dental papilla
Outer cells of dental papilla become…
dentin secreting odontoblasts
Central cells of the dental papilla become…
Promordium of dental pulp
Dental sac undergoes histodifferentation _____(later than /before) enamel organ and dental papilla?
Later than
Three types of tissues of dental sac in bell stage:
Cementum
Periodontal ligament
Alveolar process
Apposition stage is also know as …
secretory stage
What occurs during the apposition stage
Enamel, dentin, and cementum are secreted in successive layers
What happens in the maturation stage
stage is reached when matrices of hard dental tissue fully mineralize to their correct levels
How does tooth development occur
Begins in crown and proceeds to the root
What are preameloblasts
IEE cells that grow columnar and elongate and differentiate
What is repolarization
moving of nucleus away from basement membrane
What cells undergo cellular repolarization in preameloblast formation
IEE
What does IEE induce what cells to become what?
Induces dental papilla cells to differentiate into dentin-forming cells (odontoblasts)
What does IEE themselves differentiate into?
Ameloblasts (cells that secrete enamel)
Preameloblasts induce outer dental papilla cells to become what?
Odontoblasts
Dentinogenesis
Lays down dentin matrix (predentin)
When preameloblasts come into contact with the new predentin what occurs
preameloblasts differentiate into ameloblasts
What triggers enamel formation
Dentin formation
What is amelogenesis
Growth of enamel matrix
What is the enamel matrix secreted from
Tomes Process
What is the tomes process
angled distal part of ameloblast
What is an odontoblastic process
Cellular extension in length of predentin
What are odontoblastic processes contained in
Dentinal tubule
What ultimately happens to cell bodies of odontoblasts
Remain in adjoining pulp attached by odontoblastic processes
What ultimately happens to ameloblasts
lost after tooth eruption
