2. Odontogenesis
•It is a process by which tooth
moves within the jaw bones,
comes out into the oral cavity
•Primitive mouth of five week
old embryo
•Odontogenic epithelium -
primary epithelium band
divides into
• dental lamina
• vestibular lamina
3.
4.
5.
6. Development of tooth
• Similar as in placoid scales; Enamel – epidermis ;Rest part of tooth - dermis or
mesenchyme
7. • Enamel organ – Dental lamina
• Dental follicle- ectomesenchymal cells enclosing rest of enamel
organ
• Dental papillae –ectomesenchymal cells filling up the concavity of
cap
8. • Thickening of ectoderm along the margin of the jaw bone
• Basal layer of ectoderm, the malphigian layer forms
continuous solid ridge like vertical invagination into
underlying dermis
Development of tooth
9. • This forms dental lamina which retains its connection with
the outer epidermis
• Mesodermal cells multiply rapidly beneath the ectodermal in
growth or dental lamina forming a series of solid bud-like
outgrowths at intervals called tooth germs
Development of tooth
10. • Their number is as many as no of milk teeth
• Each tooth germ, the inverted cup like epithelial cap will
secrete the enamel, hence termed enamel organ
• Mesodermal aggregation beneath enamel organ is termed
dermal or dental papilla
Development of tooth
11. • Its outer columnar cells become differentiated into
odontoblasts which secrete a layer of dentine on their outer
surface
• Cells of inner epithelial layer of enamel organ similarly
becomes ameloblasts which form a cap of hard enamel
around the top and sides of dentine
Development of tooth
12. • No enamel is deposited on the root
• Dental papilla is retained as pulp
• Its central cavity goes on increasing
to become the pulp cavity
• Nerves and blood vessels enter the
pulp cavity through the basal
opening
Development of tooth
13. • Upto this stage tooth remains inside the gum
(tissue)
• Later, its eruption through overlying
epidermis is known as cutting of tooth
• Around the root of teeth appears cement or
cementum which is modified bone
• Odontoblasts become inactive when tooth is
fully formed
• However in rodents, lagomorphs,
odontoblasts remain active throughout life
and teeth continue to grow
Development of tooth
