Tooth Development Flashcards
Tooth Layers
Enamel
What does it do?
Covers anatomical crown
Enamel
What is it?
Epithelial product
Enamel
Makeup
96% inorganic
Enamel
Thickness
2mm thick maximum
Enamel
Appearance
Translucent
Enamel
Importance
Non-vital
Enamel
Characteristics
Hard (KHN 360-390) and brittle
Dentine
What is it?
Specialised connective tissue
Dentine
Characteristics
Hard (KHN 75), strong and resilient
Dentine
Makeup
~70% mineral and 20% organic (collagen)
Dentine
Contains
Dentinal tubules
Cementum
What is it?
What does it do?
Resistant to…
Mineralised (connective) tissue
Covers the roots of the tooth and provides support
Resorption
Interactions between:
Epithelium (ectoderm) gives rise to
Mesenchyme (ectomesenchyme) gives rise to
First signs of development
Enamel and the hyaline layer of the root
Dentine, pulp, cementum, periodontium (periodontal ligament and bone)
6 weeks
Stages of the tooth germ
Bud Stage
What happens?
Spherical/ovoid epithelial condensation
Cell proliferation
No histodifferentiation or morphogenesis
Cap Stage
What happens?
Cap-shaped enamel organ
Poorly histodifferentiated
Little morphogenesis
Late Cap Stage
What happens?
Some histodifferentiation. The inner and outer enamel epithelia
Some morphogenesis
Bell Stage
Early Bell Stage
Enamel Organ
Ectomesenchyme
Inner enamel epithelium (forms amelobasts (enamel)). Stratum intermedium, stellate reticulum and outer enamel epithelium
Dental papilla (forms odontoblasts (dentine) and pulp). Dental follicle (forms cementum, PDL and bone)
Bell Stage
Dentinogenesis
Cytodiffererntiation
Dental papilla cells form odontoblasts
Dentinogenesis
Matrix formation
Odontoblasts -Produce predentine (collagen rich)
Retreat inwards
Have a long cell process which forms the dentinal tubule
Dentinogenesis
Mineralisation
Predentine mineralizes forming dentine
Crown Stage
Amelogenesis
Ameloblasts
Formed from the inner enamel epithelium
Amelogenesis
Ameloblast secretes
Enamel protein matrix
Amelogenesis
Mineralisation
Virtually immediate. ~15% mineral, 65% water, 20% proteins. Rapid increase to 30% mineral (“immature” enamel)
Amelogenesis
Gradual Maturation
Further mineralisation to ~96% - this requires the removal of most of the enamel proteins
Crown Stage
Crown Complete
Root Formation
What is the root?
What are they derived from?
Signals for initiation
Dentine and cementum
Ectomesenchyme
An epithelial (root sheath) signal is required for initiation
