41 terms

Tooth Development

Tooth germ tissues
1. Ectodermal (epithelial) 2. Mesodermal (mesenchymal - CT)
What part of tooth forms first, the crown or root?
Which occurs first in development, shape or layers?
shape occurs first and then tissues are laid down to form layers
What must be completed before Cytodifferentiation can occur?
process of tooth development resulting in tooth's shape
process of differentiation of special cells to form enamel, dentin, cementum and pulp
Tooth development moves from
the incisal/occlusal/cup tip and moves apically toward root
Tooth development begins during
the sixth and seventh week of fetal development
Which teeth development first, anterior or posterior?
tooth forming/developing
Three stages of morphodifferentiation
1. Bud stage (8th wk) 2. Cap stage (9th - 10th wk) 3. Bell stage (11th - 12th wk) (none can happen until have jaw and arch appearance)
Three parts of tooth germ
1. Enamel organ 2. Dental papilla 3. Dental sac/follicle
Enamel organ develops from
ectodermal (epithelial)
Dental papilla develops from
mesodermal (CT)
Dental sac/follicle develops from
mesodermal (CT)
Enamel organ makes
Dental papilla makes
dentin and pulp
Dental sac/follicle makes
alveolar bone proper, periodontal ligament and cementum
Cells that make enamel
Cells that make dentin
Cells that make pulp
Cells that make alveolar bone proper
Cells that make PDL
Cells that make cementum
Dental papilla is located
under the enamel organ
Dental sac/follicle surrounds
the enamel organ and dental papilla
Alveolar bone proper lays
next to or connects to tooth
When tooth starts to erupt
the apical 1/3 of root is not formed yet
Completion of morphodifferentiation occurs
when the Bell stage is complete (have complete crown shape of tooth)
Four layers of enamel organ
1. Inner enamel epithelium 2. Stratum intermedium 3. Stellate reticulum 4. Outer enamel epithelium
Inner enamel epithelium
differentiates into ameloblasts the form enamel matrix. epithelial cells communicate with dental papilla
Stratum intermedium
supports the production of enamel matrix
Stellate reticulum
supports the production of enamel matrix
Outer enamel epithelium
serves as protective barrier for enamel organ
Enamel organ
formation of tooth bud in a cap shape with deep central depression
Dental papilla
condensed mass of mesenchyme within the concavity of the enamel organ
Dental sac/follicle
condensed mass of mesenchyme surrounding the enamel organ
Each individual tooth germ
must attach to epithelial tissue
First communication is
morphodifferentiation (instructs oral epithelium to thicken and grow down into CT to shape the tooth)
Inner enamel epithelial cells
cytodifferentiate into ameloblasts to lay down enamel
Steps of Morphodifferentiation
1. must have epithelial tissue and CT with cells communicating 2. oral epithelium thickens and grows down into CT forming a bud 3. tooth germ now connected to oral epithelium by dental lamina 4. continues growing apically and outward forming a cap 5. continues growing until crown shape is complete (bell stage) 6. cytodifferentiation can now begin in the crown