Tooth Development: Putting it all together Flashcards
Timing of deciduous
dentition (2)
• Eruption and
exfoliation
• Sequence of eruption
Timing of permanent
dentition (5)
• When the crown begins to calcify • When the crown is completely calcified • Completion of root development • Eruption • Sequence of eruption
First sign of tooth development is at
6-7 weeks
in utero
• Deciduous teeth begin to calcify at
13-20
weeks in utero
By —- all deciduous teeth
have begun to calcify
18-20 weeks in utero
• Deciduous teeth erupt at
6-30 months
• First part of tooth to calcify is the
crown
Stages of Tooth Development (3)
I. Crown Formation:
II. Root Formation
III. Supporting Structures
I. Crown Formation: (5)
- Initiation
- Bud Stage
- Cap Stage
- Bell Stage
- Enamel and dentin
formation
Primary Epithelial Band (2)
Horseshoe shaped
Correspond to future
dental arches
Primary Epithelial Band
Gives rise to (2)
Dental lamina
Vestibular lamina
Shh Is Expressed In The — And
Pax9 In The — Where The Tooth
Bud Would Form
Epithelium
Mesenchyme
Initiation of Tooth
Development (3)
Placode formation Epithelial outgrowth into the mesenchyme Initial odontogenic potential lies in the epithelium subsequently shifts to mesenchyme
Placode formation –
Epithelial thickening.
Initial odontogenic
potential lies in the
epithelium subsequently
shifts to mesenchyme –
the neural crest mesenchyme induces the oral ectoderm to become the dental lamina
Bud Stage (5)
Epithelial cells show no major changes Shh, Lef-1 and Eda-Edar involved in placode formation (ectoderm thickening) Mesenchyme beneath starts to condense by the factors secreted by the epithelium Cross-talk between the epithelium and the mesenchyme Odontogenic potential in the epithelium
Cap Stage
Epithelium proliferates.
Mesenchyme continue to condense.
Looks like “Cap” sitting on a ball of
mesenchyme
Tooth germ: (2)
Enamel organ – Enamel of the
tooth
Dental papilla – Dentin (outer)
and pulp (inner)
Bud to cap stage transition is
regulated by
signaling molecules
and transcription factors
Dental follicle or Dental Sac –
Supporting structures (Cementum / Periodontium / alveolar bone proper)