Tooth Development Flashcards
What are the primary embryonic layers
Ectoderm
Mesoderm
Endoderm
What is tooth enamel derived from
Ectoderm
What are all tooth structures besides the enamel derived from
Ectomesenchyme
What is the ectomesenchyme
Part of the neural crest that develops beside the primitive nervous system (ectoderm)
What do teeth develop from
Tooth germs
What is another name for the neural crest
Ectomesenchyme
What is developed in the initiation stage
Dental lamina
What are the different stages of tooth development
Initiation Morphogenetic Cytodifferentiation Matrix secretion Root formation
Name in order of first to last, the parts of tooth that are developed
Dental lamina Bud Cap Bell Erupting tooth Bone
When does the primary epithelial band develop
Approximately 6 weeks
What does the primary epithelial band appear as
Thickening of epithelium of embryonic mouth (stomodaeum)
When does the dental lamina develop
Approximately 7 weeks
What does the primary epithelial band divide into
Vestibular lamina and dental lamina
What does the vestibular lamina form
Buccal sulcus
What does the dental lamina form
Enamel organ
What develops at the morphogenesis stage
Bud and cap
When does the enamel bud develop
8-10 weeks
What happens during the bud stage
Dental lamina thickens into an enamel bud and the dental papilla appears
When does the enamel cap develop
11 weeks
What happens during the cap stage
Enamel organ forms a cap over the papilla and the external enamel epithelium and internal enamel epithelium meet at the cervical loop
What develops during cytodifferentiation
The bell
When does the bell develop
14 weeks
What happens during the bell stage
There are more cell layers differentiated and tooth shape is being defined
What are the layers of the enamel organ at the bell stage
Internal enamel epithelium
Stratum intermedium
External enamel epithelium
Stellate reticulum
What happens at 12 weeks
An extension appears on the lingual side of the dental lamina - this is the dental lamina of the permanent tooth
What develops during matrix secretion
The eruption of the tooth
When does the late bell stage take place
18 weeks
What does the late bell stage look like
Crown shape is well defined, apposition of enamel and dentine begins
What develops into odontoblasts
Dental papilla cells adjacent to the internal enamel epithelium
What do odontoblasts do
Lay down a dentine matrix
What forms enamel
Ameloblasts
What happens during dentinogenesis
Odontoblast differentiation from internal enamel epithelium
Deposition of dentine matrix
Mineralisation of dentine
What is unmineralised dentine called
Predentine
How is enamel formed
The protein matrix is deposited and then the organic part is removed and mineralisation is completed - maturation
What happens during ameloblast differentiation
Dentine induces IEE cells to differentiate into ameloblasts which elongate becoming columnar and the nucleus migrates to the basal end of the cell
What happens during the secretory phase of amelogenesis
Ameloblasts become secretory cells which synthesise and secrete the enamel matrix proteins
The matrix is then partially mineralised
What happens during the maturation phase of amelogenesis
Most of the matrix proteins are removed, mineral content of enamel is increased
Mature enamel is 95% mineral
What happens during the protection phase of amelogenesis
Ameloblasts regress to form a protective layer - the reduced enamel epithelium
Eruption takes place and epithelial attachment forms
What is root shape defined by
The apical growth of the cervical loop
When in root formation, what is the cervical loop called
Hertwig’s epithelial root sheath
What is Hertwig’s epithelial root sheath
2-cell-layered structure
What does HERS induce
Formation of root dentine
What happens once the initial layer of root dentine is formed
HERS breaks up
What do the remnants of HERS appear as once they are broken up
Debris of malassez we high may develop into a cyst
What differentiates into cementoblasts
Mesenchymal cells from the follicle
What do cementoblasts form
Cementum
What are Sharpey’s fibres
Fibres from the developing PDL
Name the type of tissue, origin and products of the enamel organ
Epithelium
Ectoderm
Enamel
Name the type of tissue, origin and products of the dental papilla
Ectomesenchyme
Neural crest
Dentine and pulp
Name the type of tissue, origin and products of the dental follicle
Ectomesenchyme
Neural crest
Cementum, PDL and part of the alveolar bone
What is hypodontia
Having less teeth than you are supposed to have
What is supernumerary
An extra tooth
