This document discusses tooth development from the early embryonic stages through formation of the tooth bud and germ. It describes how the three germ layers give rise to the tissues of the body, including the ectoderm forming the oral epithelium where teeth develop. Tooth formation begins with thickening of the oral epithelium into dental lamina, from which 10 tooth buds arise. The buds develop through bud, cap and bell stages as the enamel organ, dental papilla and follicle form. Different layers of the enamel organ and transient structures like the enamel knot are involved in shaping the developing tooth and determining cusp locations.

1. Topic : Tooth Development I
DR VINOD KUMAR R.B
PROF & HEAD
DEPT OF ORAL PATHOLOGY & MICROBIOLOGY
MALABAR DENTAL COLLEGE & RESEARCH CENTRE

2. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Week 2 – The Two-Layered Embryo
 Bilaminar embryonic disc – inner cell mass divided into two sheets
 Epiblast and the hypoblast
Together they make up the bilaminar embryonic disc

3. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings
Week 3 – The Three-Layered Embryo
 Three Germ Layers*
 Ectoderm – (tissues covering outside the body
eg.epidermis ,hair etc
 Mesoderm – connective tissues heart,muscle
,blood cells,bone ,dermis etc
 Endoderm – tissues lining inside the body/lung
stomach,intestine etc

5. Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

6. Crest of neural fold
During the development of the neural tube small groups of
ectodermal cells break away from the margins of the neural plate
and come to lie on either side of the neural tube.They constitute
the neural crest cells
Neural crest cells
Neural tube

8. In the cranial region the neural crest cells contribute the
meninges and much of the cartilage and bone of the facial
skeleton ,tissues which at one time were thought to arise from
the mesoderm
In order to distinguish betweeen the origins of the mesodermal
cells they can be referred to as endomesenchyme(mesodermal
origin) and ectomesenchyme(neural crest origin)

9. Location of tooth formation- tooth formation occurs at the oral
epithelium (ectoderm) of maxillary and mandibular process of the embryo
6 weeks old embryo
Maxillary process
Mandibular process
auricle
eye
Coronal section
Oral epithelium of maxillary
and mandibular processes
tongue
nasal septum

10. 6 weeks old embryo
The crown –rump length (CRL) of the embryo is only
11 mms when the first sign of tooth formation
occurs(6th week of IU life)

11. Stages of tooth
development
1. Bud stage
2. Cap stage
3. Bell stage
4. Appositional stage (mineralization)
5. Root formation
6. Eruption
(epithelial ingrowth into ectomesenchyme)
(further epithelial growth)
(histo- and morpho-differentiation)
(formation of enamel and dentin of crown)
(formation of dentin and cementum of root)
Oral Histology and Embryology by Leslie P. Gartner, 1988

12. Bud stage
Mx
Mn
dental lamina
tooth bud
developing
maxillalry bone
tongue
palate
http://www.iob.uio.no/studier/undervisning/histologi/index.php
• Dental lamina
- is the horse shoe-shaped
epithelial band from oral epithelium
- one dental lamina per arch
- 10 tooth buds arise from dental lamina
corresponding to the position of future
primary teeth
developing
mandibular bone

13. Mx
Mn
vestibular lamina
http://www.iob.uio.no/studier/undervisning/histologi/index.php
vestibule
Bud stage
Another thickening arises lateral to the dental lamina and is called
vestibular lamina .It subsequently hollows out to form the vestbule

14. Labial frenum
Vestibule

15. ectomesenchymal cells
http://www.iob.uio.no/studier/undervisning/histologi/index.php
Bud stage
The enamel organ is shaped like a bud. It consists of epithelial cells
and is surrounded by a condensation of ectomesenchymal cells

16. condensation of
ectomesenchymal cells
around tooth bud
http://www.iob.uio.no/studier/undervisning/histologi/index.php
Bud stage

17. Cap stage
1. Enamel organ (=dental organ)
(proliferation of epithelial cells)
2. Dental papilla
(condensation of ectomesenchymal cells)
3. Dental sac (=dental follicle)
(capsule like condensation of
ectomesenchymal cells)
1
2
3
http://www.iob.uio.no/studier/undervisning/histologi/index.php
The enamel organ undergoes differential growth and becomes cap shaped
At this stage the developing tooth
bud consists of 3 parts

18. Cap stage
1. Enamel organ (=dental organ)
(proliferation of epithelial cells)
2. Dental papilla
(condensation of ectomesenchymal cells)
3. Dental sac (=dental follicle)
(capsule like condensation of
ectomesenchymal cells)
1
2
3
http://www.iob.uio.no/studier/undervisning/histologi/index.php
The enamel organ undergoes differential growth and becomes cap shaped
At this stage the developing tooth
bud consists of 3 parts

19. Future tooth products-derivatives
1. Enamel organ
2. Dental papilla
3. Dental sac1
2
3
enamel
dentin
pulp
cementum
periodontal ligament
alveolar bone
connective tissues of gingiva
http://www.iob.uio.no/studier/undervisning/histologi/index.php

20. Tooth germ means
1. Enamel organ
2. Dental papilla
3. Dental follicle1
2
3
http://www.iob.uio.no/studier/undervisning/histologi/index.php
+
+

21. Enamel organ of cap stage consists of 3 layers –inner enamel
epithelium,outer enamel epithelium and stellate reticulum. Temporary
structures found during cap stage includes enamel knot,enamel cord and
enamel navel
2
1
3
1) Inner enamel ep
2) Outer enamel ep
3) Cervical loop
4) Stellate reticulum
5) Enamel knot
6) Enamel cord
7) Enamel navel
4
5
6
7
transient structure
during cap stage
http://www.iob.uio.no/studier/undervisning/histologi/index.php
(inner+outer enamel ep.)

22. 2
1
3
1) Inner enamel ep
2) Outer enamel ep
3) Cervical loop
4) Stellate reticulum
5) Enamel knot
6) Enamel cord
7) Enamel navel
4
5
6
7
transient structure
during cap stage
root formation
generate enamel
location of cusp?
http://www.iob.uio.no/studier/undervisning/histologi/index.php
The inner enamel epithelium gives rise to ameloblasts the cells that form enamel,stellate
reticulum consists of cells with cushion like consistency and protects the delicate enamel
forming cells
.Enamel knot determines the site where the first cusp forms.Enamel cord probably acts as
a resevoir of cells for the enamel organ
(protect inner enamel ep.)