Tooth Development Flashcards
What is the structure of a tooth?
Enamel layer Amelodentinal junction Dentine Pulp Cementum
What is the make up of enamel?
96% mineral
1-2% matrix
2% water
What is the make up of dentine?
70% mineral
20% matrix
10% water
What is the make up of cementum?
65% mineral
23% matrix
12% water
What is the make up of bone?
60% mineral
25% matrix
15% water
Properties of enamel
Covers anatomical crown Epithelial product 96% inorganic 2mm thick max Translucent Non-vital Hard Brittle
Properties of dentine
Specialised connective tissue Hard Strong and resilient 70% mineral 20% organic Collagen Dentinal tubules
Properties of cementum
Mineralised tissue Mineralised connective tissue Covers tooth roots Tooth support Resistant to resorption
What do epithelial interactions give rise to?
Enamel
Hyaline layer of root
What do mesenchyme interactions give rise to?
Dentine
Pulp
Cementum
Periodontium
When is the first signs of tooth development?
6 weeks
Stages of the tooth germ
Bud Stage
Cap Stage
Bell Stage
Crown Stage
What happens at the bud stage?
Spherical/ovoid epithelial condensation
Cell proliferation
No histodifferentiation or morphogenesis
What happens at the cap stage?
Cap shaped enamel organ
Poorly histodifferentiated
Little morphogenesis
What happens late cap stage?
Some histodifferentiation (inner and outer enamel epithelia) Some morphogenesis
What happens at the early bell stage?
Enamel organ:
- Inner enamel epithelium forms amaloblasts
- stratum intermedium
- stellate reticulum
- outer enamel epithelium
Ectomesenchyme
- dental papilla forms odontoblasts and pulp
- dental follicle forms cementum, PDL and bone
Dentinogenesis
Cytodifferentiation - dental papilla cells form odontoblasts Matrix formation - odontoblasts produce collagen rich predentine - odontoblasts retreat inwards - odontoblasts have a long cell process forming dentinal tubule Mineralisation - predentine mineralises forming dentine
Amelogenesis
Inner enamel epithelium form ameloblasts Ameloblast secrete enamel protein matrix Virtually immediate mineralisation - 15% mineral, 65% water, 20% proteins - rapid increase to 30% mineral = immature enamel Gradual maturation - further mineralisation to 96% - requires removal of most of the enamel proteins
What happens at the crown stage?
Dentinogenesis and amelogenesis
Root formation
Root = dentine and cementum
Dentine and cementum derived from ectomesenchyme so requires epithelial signal for initiation
