2. Stages in the life cycle of a
tooth
1. Growth
Physiologic process
a. Initiation
b. Prolifiration
c. Histodifferentiation
d. Morphodifferentiation
e. Apposition
2. Calcification
3. Eruption
4. apposition
3. 3 developmental process before
function
Grow
Calcify
Erupt
Unlike kidney and heart.. Afte growth ..
Function
Unlike bone… growth and calcify… function
4. Initiation stage
6th weeks intra
uterine life: first sign
of tooth
development
Dental lamina:
represent the first
sign of tooth
development. This
is the GERMINAL
BAND OF
EPITHELIUM
5. Function of dental lamina
Initiate the development of the whole
deciduous dentition
Initiate the development of the succedenuous
teeth, by proliferation of bud from enamel
organ
Initiates the development of the accesional
teeth from the distal extention of the dental
lamina
6. Vestibular lamina
After the dental
lamina, the
vestibular lamina will
arise as another
ectodermal
thickening, but
anterior to the dental
lamina.
Then this will split to
form the vestibular
groove the future
vestibule.
7. Bud stage
At certain point on DL
representing the location of
10 manibular and 10
maxillary deciduous teeth
cells multiply still more rapidly
and form a knob like
projections oward the
mesoderm
Down ward growth creating
dental sac, dental papila and
dental organ
For the mandibular anterior
6th to 7 weeks
Max anterior 7th to 7 ½ week
Deciduous molars 8th week
8. Cap stage
The epithelial bud
will continue to
proliferate and
expand latrally
Defferent part of the
bud will show
unequal growth
leading to the
formation of a cap
stage dental organ(
with invagination)
9. 3 layers of cap stage
Outer dental epithelium
Inner dental epithelium
Stellate reticullum
(enamel pulp,
Filled with mucoid fluid
rich in albumin)
Star shape cell
During late cap stage
Stratum intermedium :
flat cell between inner
dental epithelium and
stalate reticulum.
10. Enamel knot: bud like enlargement , germinal
center for the demand of cell growth of tooth
Enamel cord: vertical extension of the enamel
knot that maintain the cap shape dental organ
Enamel naval: attachment of enamel cord to
outer dental epithelium
14. Dental papilla
The invaginated part of
the dental organ is
occupied by
condensation of
mesenchymal tissues.
Peripheral cells (
cuboidal – columnar)
differentiates into
odontoblast through the
stimulation of the cell of
the IEE
ODONTOBLAST –
formtive cell of dentin
Central part will be the
pulp
15. Membrana preformativa
Former basement
membrane
(separating the
dental papilla from
the IDE
FUTURE dentino
enamel junction
16. Tooth germ and dental sac
During bell stage, the mesodermal tissue
arround the enamel orgarn and the dental
papilla differentiates into connective tissue
capsule, dental sac.
As a resulth 3 tooth germs are developed.
a. Dental organ – will give rise to enamel tissue
b. Dental papilla – give rise to dentin and pulp
c. Dental sac – give rise to cementum, pdl and
alveolar bone.
17. Dental organ
Give rise to enamel
Play an active role in the formation of dentin
Play a role in formation of root via HERS or
hertwig’s epithelial root sheath. (from the
junction of the IDE and ODE)
Produces enamel cuticle: last product of
ameloblast
Remain as epithelial attachment of the neck of
the toth after the tooth has erupted
18. histodifferentiation
Peripheral cells of the inner dental epithelium
differentiates into ameloblast (formative cells
of enamel)
With the influence of the ameloblast, the
formative layer of dentin known as the
ODONTOBLAST are formed from the cells of
the periphery of the dental papill
19. Morphodifferentiation
The shape and form of the crown is determine
by the membrana preformativa
20. Fate of dental lamina
The remnant should be calcified and be
resorbed by osteoclast because it has no
function
But, some group of epithelial cells may persist
to stay (called gland of serres) and
differentiates into ENAMEL
MASS, SUPERNUMERARY
TEETH, TUMORS OR CYST (
ameloblastoma)
