Man-Kyo Chung, DMD, PhD ([email protected])...

Man-Kyo Chung, DMD, PhD

([email protected])

Assistant Professor

Department of Neural and Pain Sciences

University of Maryland Dental School

Proliferation (increase in number)

Migration (change in location)

Differentiation (specialization)

Ameloblasts forming enamel Odontoblasts forming dentin Cementoblasts forming cementum

epithelial cells

ectomesenchymal cells

Enamel

Dentin

Cementum

Pulp

zygote

(a cell from fertilization)

Mesoderm (connective tissues / heart, muscle, blood cells, bone, dermis etc)

Ectoderm (tissues covering outside the body /epidermis, hair , nails etc)

Endoderm (tissues lining inside the body / lung, stomach, intestine, liver etc)

<trilaminar germ disc>

Oral Histology and Embryology by Leslie

P. Gartner, 1988 bilaminar germ disc

<1 wk ~2 wks

~3 wks

3. connective tissues of head and neck (bone, cartilage, muscles, tooth etc)

epithelium

(Ectomesenchymal origin)

embryonic

connective tissue

ectodermal origin

ectoderm

neural tube

neural crest

1. brain (neuroectodermal origin)

2. sensory ganglia

6 weeks old embryo

Maxillary process

Mandibular process

Oral Histology and Embryology by

Leslie P. Gartner, 1988

auricle

eye

Coronal section

Oral epithelium of maxillary

and mandibular processes

tongue

nasal septum

1. Bud stage

2. Cap stage

3. Bell stage

4. Appositional stage (mineralization)

5. Root formation

6. Eruption

(bud-like outgrowth from dental lamina)

(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

* Initiation (band-like outgrouwth of oral epithelium)

Mx

Mn

dental lamina

Dental lamina

• At ~6 weeks of embryo

• outgrowth of epithelial band

from oral epithelium

• horse-shoe shape

• one dental lamina per arch

Mx

Mn

dental lamina

tooth bud

developing maxillalry bone

tongue

palate

http://www.iob.uio.no/studier/undervisning/histologi/index.php

• Tooth bud

- Localized outgrowth of epithelial cells

from dental lamina

- 10 tooth buds per lamina

developing mandibular bone

Mx

Mn

vestibular lamina


vestibule

ectomesenchymal cells


condensation of ectomesenchymal cells around tooth bud


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


1. Enamel organ

2. Dental papilla

3. Dental sac 1

2

3

enamel

dentin pulp

cementum periodontal ligament alveolar bone connective tissues of gingiva


1

2

3


Transformation of a cell mass into morphologically and functionally distinct components

Secreting proteoglycans (absorbing water increase extracellular space)

1) Outer enamel epithelium

2) Stellate reticulum

3) Inner enamel epithelium

desmosome

Flattened (squamous or cuboidal)

Star shaped

Elongated and polarized (columnar)

Enamel organ

2

1

3

1) Inner enamel ep

2) Outer enamel ep

3) Cervical loop


5) Enamel knot

6) Enamel cord

7) Enamel navel

4

5

6

7

transient structure during cap stage


(inner+outer enamel ep.)

2

1

3

1) Inner enamel ep

2) Outer enamel ep

3) Cervical loop


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?


(protect inner enamel ep.)


(tooth bud of

permanent tooth)

1. Tooth shape is identifiable.

2. Further differentiation of enamel organ

1) outer enamel ep.

2) inner enamel ep.

3) stellate reticulum

4) stratum intermedium

3

2

1 4


stratum intermedium

inner enamel ep

basement membrane

dental papilla


Cusp

tip

root

differentiated

to ameloblast

without proliferation

Keep proliferating

and migrate

downward

older taller polarized

younger shorter unpolarized


1. oral ep.

2. outer enamel ep.

3. stellate reticulum

4. inner enamel ep.

5. dental papilla

6. cervical loop

3

2

1

5

4

6

blood

vessels


Stage of mineralization

oral epithelium

dental lamina

mesenchymal

cells bud

Cap

m

inera

liza

tion

bell

1

signal

proliferation

1

epithelium

mesenchyme

oral epithelium

dental lamina

inner enamel epithelium

preameloblast

mesenchymal

cells

preodontoblast

1

2

2

epithelium mesenchyme

1

2

3

4

5

6

7

8

9

1

2

3

4

5

6

7

8

9

10

11

12

13

a

b

c

d

e

f

g

h

i

a

b

c

d

e

f

g

h

i

j

k

l

m

Preameloblasts Preodontoblasts

bud

Cap

m

inera

liza

tion

bell

oral epithelium

dental lamina

inner enamel epithelium

preameloblast

ameloblast

mesenchymal

cells

preodontoblast

odontoblast

Predentin

enamel matrix

enamel

dentin

bud

Cap

m

inera

liza

tion

bell

1

2

3

odontoblasts preameloblasts

ameloblasts

Predentin (dentin matrix)

dentin enamel matrix

3

3

2

8

5

4

6 7

9

1 http://www.iob.uio.no/studier/undervisning/histologi/index.php

stratum intermedium

ameloblasts

enamel

dentin

predentin

odontoblasts


Man-Kyo Chung, DMD, PhD ([email protected])...

Documents

Transcript of Man-Kyo Chung, DMD, PhD ([email protected])...