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Tooth development,amelogenesis and dentinogenesis,

Preparation: tooth development X5

Institute of Histology and Embryology

RNDr. Lucie Lantov, Ph.D. (lucie.lantova@lf1.cuni.cz)

Oral Histology and Embryology B81134

25.3. 2014

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TOOTH FORMATION two teeth sets

- primary dentition (deciduous teeth)- secondary dentition (permanent teeth)

ectodermal origin enamel mesenchymal origin dentin, pulp, cementum, periodontal ligament

neural crest cells from neuroepithelium; form e.g. spinal ganglia, facialbones and CT, heart septa, melanocytes

ectodermal-mesenchymal interactions

STAGES dental laminae 6 weeks; upper and lower jaw

- U-shaped thickened oral ectoderm (action of neural crest cells)

+ vestibular laminae vestibule bud stage (8 weeks) dental lamina grows into neural crest-derived

mesenchyme; 10 buds in each jaw cap stage (10 weeks)

bell stage (3 months) enamel, dentin development root development

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STAGES

Sadler 2012

bud stage (8 w.) cap stage (10 w.)

bell stage (3 months)

tongue vesible

6 months

7 weeks 9 weeks

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upper lip

enamel organ

mandible(intramembranousossification)

Dp. Hist. Embr.

160mm fetus

lower lip

vestibule

vestibule

tongue

hard palate

(intramembranousossification)

nasal cavity

X5 tooth development

tooth primordium

HE

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BUD STAGE, 8 weeks dental papillacondensed dental mesenchymal cells

condensation ofmesenchymal cells

Nanci 2008 early bud stage

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BUD STAGE, 8 weeks

*

HElate bud stage/early cap stage

dental lamina

condensed mesenchyme(dental papilla)

enamel knot

oral epithelium

Dp. Hist. Embr.

invagination of tooth bud cap

shape

enamel knot- induced by dental papilla

- within overlying ectodermalepithelium

- signalling centre moleculesfor differentiation of dental capepithelium into enamel organ

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CAP STAGE, 10 weeks enamel organ

- from dental cap epithelium- outer enamel epithelium

(ameloblasts)- inner enamel epithelium

(ameloblasts)- stellate reticulum loosely

arranged epithelial core(reticular epithelium)

dental papilla mesenchyme(neural crest-derived) proliferatesinto enamel organ

dental sac mesenchymecondensation around toothprimordium

permanent tooth bud outgrowthof dental lamina

early cap stage

Ross, Pawlina 2011

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CAP STAGE, 10 weeks

outer ameloblasts

HE

stellate reticulum

dental sac

dental papilla

oral epithelium

Dp. Hist. Embr.

ossifyingmandible

dental lamina

permanent

tooth bud

inner ameloblasts

late cap stage

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invagination of dental papilla bell shape

final crown shape determined by enamel organ dental papilla dental pulp (when first calcified matrix at the cusp) histo-differentiation of ameloblasts and odontoblasts

hard tooth components formation

stratum intermedium cells above inner ameloblasts

ameloblasts columnar (inner and outer)- induce differentiation of odontoblasts- inner formation of enamel

odontoblasts- from dental papilla surface mesenchymal cells- formation of dentin- dentin stimulates production of enamel

differentiation of ameloblasts differentiation of odontoblasts dentinformation enamel formation

BELL STAGE, 3 months

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BELL STAGE, 3 months

outer ameloblasts

HE

stellate reticulum

dental sac

dental papilla

oral epithelium

Dp. Hist. Embr.

ossifyingmandible

dental lamina

inner ameloblasts

stratum intermedium

odontoblasts

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change of polarity reverse polarity

- basal cell part (facing dental papilla) apicalregion (nucleus moves to the opposite side)

terminal differentiation of ameloblasts

- after predentin formation secretory-stage ameloblast

SECRETORY-STAGE AMELOBLAST

narrow, base attached to stratum intermedium cells nucleus, mitochondria basal cytoplasm GA, GER apical cytoplasm junctional complexes, actin filaments

Tomes' process- upper pole microtubules, secretory vesicles- proximal and distal portion (surface)- crystals formed at both process surfaces

INNER AMELOBLAST DIFFERENTIATION

Nanci 2008

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cell organelles development GER (apical), GA (above nucl.), mitochondria

nuclei move basally odontoblast process enlargement ECM secretion predentin matrix vesicles (calcium and phosphate ions) release high ion

concentration hydroxyapatite crystals formation

odontoblast retreat into dental papilla Tomes' fibre

ODONTOBLAST DIFFERENTIATION

Berkowitz, Holland 2002

inner ameloblastdifferentiation

odontoblastdifferentiation

mesenchymalcell

fibroblast

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DENTIN AND ENAMEL FORMATION

Carlson 1999

M-dental papillamesenchymal cells

OD-odontoblast

differentiationA-inner ameloblastsSI-stratum intermediumSR-stellate reticulumOA-outer enamel epith.

V-vesselP-dental pulpO-odontoblastsPD-predentinD-dentinE-enamelA-inner ameloblastsSI-stratum intermedium

M

OD

A SI

SR OA

A

SI

P

O

V V

PD

D E

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during 4th month

first mineralized tooth component

1 - organic matrix production predentin- type I collagen (extracellular polymerization into fibrils)

- proteoglycans (containing chondroitin- and keratan-sulphate)- osteocalcin, dentin phosphoprotein and sialoprotein (mineralization)

2 - matrix vesicles production and release into predentin

- high calcium and phosphate ion concentration initiation of HA crystalsformation growth matrix vesicle rupture crystal fusion

DENTINOGENESIS

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1-PRESECRETORY STAGE

ameloblast differentiation2-SECRETORY STAGE (matrix production) secretory-stage ameloblasts organic matrix formation first proteins (amelogenins, ameloblastins,

enamelins, tuftelins) important for space organization and mineralization enamel matrix deposited on dentin, immediately partially mineralized thickness of future enamel is achieved

3-MATURATION STAGE maturation-stage ameloblasts transport function; cyclical morphological

alterations (cyclical entry of calcium ions) ruffled/smooth border amelogenin, ameloblastin removal

calcium and phosphate ions influx into matrix, mineralization

vascularization transport from blood to ameloblasts stratum intermedium enamel formation enamel reticulum reduction, outer enamel epithelium

degeneration inner ameloblast degeneration after enamel is fully formed (time of tooth

eruption); cervical epithelium forms junctional epithelium

AMELOGENESIS

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AMELOGENESIS, secretory stage 1 - interrod enamel formation at surface of proximal portion of

Tomes' process pit (participation of several ameloblasts) 2 - rod enamel formation at surface of distal portion of Tomes'process fills the pit (one ameloblast)

Berkowitz, Holland 2002

Nanci 2008

TEM

DEJ-dentino-enameljunction

sg-secretory granulesdpTP-distal portion

of Tomes'processppTP-proximal portion

of Tomes' processIR-nterrod enamel

IRIR IR

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AMELOGENESIS, DENTINOGENESIS

A

SI

PO

PD

DE

SR

SI

E

A

SR

D

PD

O

P

P-dental pulp O-odontoblasts PD-predentin D-dentin E-enamel A-inner ameloblastsSI-stratum intermedium SR-stellate reticulum

HE

Dp. Hist. Embr.

ROOT FORMATION

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when dentin and enamel formation well advanced

epithelial root sheathHertwig's sheath- outer and inner ameloblasts come together in neck region- grows along dental papilla surface

- ameloblasts induce differentiation of odontoblast

cementum formation- inner dental sac cells cementoblasts cementum production,

deposition on dentin

periodontal ligament- outer dental sac cells

jaw bone

- partly outer dental sac cells

ROOT FORMATION

ROOT FORMATION6 months

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ROOT FORMATIONouterameloblasts

innerameloblasts

stellatereticulum

enamel

dentin

predentinodontoblasts

dental pulp

epithelial root sheath

epithelial root sheath

Nanci 2008HEDp. Hist. Embr.

6 months