Development of Human Periodontium (1)

8/13/2019 Development of Human Periodontium (1)

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DEVELOPMENT OF HUMAN

PERIODONTIUM

DR. SHEEJA .S. VARGHESE

Saveetha dental college


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Mammalian periodontium could be regarded

as the most complex type of tooth

attachment with regard to structure and

function


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Evolution of tooth attachment

ACRODONT

PLEURODONT

THECODONT


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Variations in thecodontal

attachments in mammals

Form and function of

teeth(homodont,hetrodont)

Tooth replacement pattern (polyphidonty,monophydonty, diphidonty .semidiphidonty)

Eruption pattern (continuously growing,slow but continuous, no continuous

eruption)

VARIATIONS IN THECODONTAL ATTACHMENTS

IN MAMMALS DEPENDS ON


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SIX GROUPS OF THECODONTAL

PERIODONTIUM

Group-1 : incisors and canines of omnivores, herbivores,carnivores

Group-2:premolars and molars of omnivores and carnivores

Group-3: premolars and molars of herbivores

Group-4: incisors of rodents , some molars of guinea pigs ,

rabbits

Group-5: Dolphins and whales

Group-6: some molars of rodents


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FOR THE DEVELOPMENT OF HUMAN

PERIODONTIUM

PRECURSER

CELLS

SIGNALLING

MOLECULES

INDUCTION , COMPETENCE,

DIFFERENTIATION


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PRECURSER CELLS

DENTAL

ECTOMES-

ENCHYME

ORAL

EPITHELIAL

CELLS

NEURAL CREST ORIGINECTODERM OF 1ST

PHARYNGEAL ARCH


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NEURULATION & NEURAL CREST CELLS


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EPITHELIAL MESENCHYMAL

TRANSFORMATION OF NEURAL CREST

CELLS-by changing cytoskeletal organization and cell

adhesive property.

Molecular level changes in neural crest cells

1. Expression of snail zinc finger transcription factor

family that suppress E cadherin

2. Expression of BMP protein and fibroblast growthfactor signaling pathways


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DERIVATIVES OF NEURAL CREST

CELLS


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PRIMITIVE ORAL CAVITY


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BRANCHIAL(PHARYNGEAL) ARCHES


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ORAL EPITHELIUM (1STARCH EPITHELIUM)


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SIGNALLING MOLECULESMORPHOGENSDifferentiation & migration of cells thereby dictate

morphology and function of developing tissues

GROWTH FACTORS- Cellular proliferation ,migration and survival

TRANSCRIPTION FACTORS Homeodomain proteins , PAX

proteins etc

--Regulates gene transcription

NUCLEAR RECEPTORS -Steroid/ Thyroid/ retinoic acid super

family

--Hormone activated transcription factors


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MORPHOGENS

TGFsuper familyBMP, Activin, TGF

Retinoic acid

Hedgehog protein

Wnt protein


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HOMEODOMAIN PROTEINS

Transcription factor family with Helix turn-Helix motif.

They contain highly conserved 60 amino acid

sequence(homeo domain) which can bind to target

genes

Genes encoding these proteins are called as Homeobox

genes.

These genes which has a small (180bp) conserved

region of DNA first identified in homeotic genes of

drosophilla

Hox genes are mammalian homeobox genes which

resemble homeotic genes.In mammals there are 39 hox

genes and many non hox homeobox genes identified


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Genes expressed during tooth developmentBarx BarH1 homologue in vertebrates (TF)

Bmp Bone morphogenetic proteins (SP)

Dlx Distaless homologue in vertebrates (TF)

Fgf Fibroblast growth factor (SP)

Gli Glioma-associated oncogene homologue (zinc finger protein)(TF)

Hgf Hepatic growth factor (SP)

Lef Lymphoid enhancer-binding factor 1 (TF)

Lhx Lim-homeobox domain gene (TF)

Msx Msh-like genes in vertebrates (TF)

Otlx Otx-related homeobox gene (TF)

Pax Paired box homeotic gene (TF)

Pitx Transcription factor named for its expression in the pituitary gland

Ptc Patched cell-surface receptor for sonic hedgehog (SHH)

Shh Sonic hedgehog (SP)

Slit Homologous to Drosophila slit protein (SP)

Smo Smoothed PTC coreceptor for SHH

Wnt Wingless homologue in vertebrate (SP)

RunX2/ Runt-related transcription factor-2

Cbfa1 Core binding factor alpha 1


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BRANCHIAL HOX CODE


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ODONTOGENIC HOMEOBOX CODE


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EPITHELIAL MESENCHYMAL

INTERACTION AT VARIOUS STAGES


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MOLECULAR FACTORS INVOLVED IN

PERIODONTAL DEVELOPMENT

TRANSCRIPTION FACTORS(Genes involved)

Homeobox genes Msx1, Msx2, Dlx1, Dlx2, Dlx3,

Otlx2,Barx1

Pax genes Pax9, Pax6Lef1, Gli2/Gli3,Shh,Nfi-c

GROWTH FACTORS & MORPHOGENS

TGF 1 & 2, BMP2, 3, 4, &7, Activin, FGF 4,8 & 9,Hepatocyte growth factor, IGF1,PDGF


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ROOT & PERIODONTIUM BEGINS TO

DEVELOP AFTER HERS FORMATION


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DEVELOPMENT OF CEMENTUM

Cells involved

Signaling molecules

Matrix synthesis

Mineralization


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CELLS INVOLVED

Dental follicle properEctomesenchyme-Neural crest derivative

HertwigsEpithelial Root Sheath

OEE and IEE-Oral epithelium-Ectoderm of

first arch derivative


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Dental follicle has two differentiation compartments

1.Alveolar clade (produces osteoblastand fibroblast)

2.Cement clade (produces

cementoblast and fibroblast)


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AEFC C bl CIFC C bl


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AEFC Cementoblasts CIFC Cementoblasts

Morophology Similar to periodontal ligament fibroblast

(gene expression is different)

CuboidalSimilar to osteoblast

Rate of Matrix production Slow and constant rate More rapid than AEFC , not constant

Mode of Matrix

production

Unipolar Multipolar

Cementoid Not present Present

Response to regulatory

factors

Mild Respond well PTH signaling pathway, growth

harmone

Regulatory factor for

differentiation

Run X2 / Cbfa1 Run X2 / Cbfa1

Precursor cells Dental follicle / HERS

Periodontal ligament stem cell/ERM

- Odontogenic origin

Same

May also have non odontogenic origin with

alveolar bone or other extra ligamentary tissues


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AEFC Cementoblasts CIFC Cementoblasts

Matrix production

Collagen

Non collagenous proteins

Growth factors

Type I, Type III, V, VI,XII Same

Major proteins BSP and OPN Major proteins BSP and OPNmore

than AEFC

DSP and Osteocalcin are not produced Produced

Cementum Attachment protein is produced Produced

Proteoglycans - lumican, fibromodulin,

versican, decorinnot present

Present

EMPpresent Not present

Cementum derived growth factor present Present


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SIGNALING MOLECULES INVOLVED IN CEMENTOGENESIS

BMP

BMP-2, BMP-4 & BMP-7 known to promote differentiation of

putative cementoblast precursor cells.

PDGF, IGF

- Promote cementum formation by altering cell cycle activities

FGF

- Promoting cell proliferation, migration and vasculogenesis.

Epithelial factors

- Enamel proteins, parathyroid hormone related protein &

basement membrane constituents may play a role in

cementogenesis.


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(Cntd)

Major matrix proteins with cell adhesion motifs

- Bone sialoprotein and osteopontin

- Contain the cell adhesion motif arginineglycine asparticacid (RGD sequence) - promoting adhesion of selected cells

to the newly formed root surface.

- Bone sialoprotein promotes mineral formation

- Osteopontin regulates mineral growth

Gla protein

- Contain carboxy glutamic acid, calcium binding amino acid

that may facilitate interaction with hydroxy apatite.

Bone Gla protein (osteocalcin) regulate extent of mineralisation

C ll


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Collagens

- Type I collagen is the predominent collagen and it accommodates

mineral deposition

Type III & Type XII collagen is also found in small amountTranscription factors

Runx-2 (runt related transcription factor 2) also known as cbfa 1

(core binding factor alpha 1) is likely to be involved in the

differentiation of cementoblast.BMPs promote expression of Runx2

Other factors

Alkaline phosphatase - in mineralization

Proteoglycanaccumulate at the dentin cementum junction

with other protein such as bone sialoprotein and osteopontin initiate

mineralization and fiber attachment .


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Cementum Attachment Protein (CAP)

It is a 56 or 65 kDa collagenous protein which is different from

other collagen types and adhesion molecules.

It regulates differentiation of cementoblast lineage by inducing and

enhancing the differentiation of putative cementoblastic progenitors

and has the capacity to recruit fibroblastic progenitors to

cementoblastic lineage.

Cementum derived growth factor

It is a IGF like molecule

It is the growth factor specific to cementum present in the extra

cellular matrix.

It is mitogenic to gingival fibroblast and alveolar bone cells.


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MATRIX SYNTHESIS-MAJOR EVENTS

Migration

Attachment

Proliferation

Differentiation

Matrix synthesis


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MIGRATION

Migration of dental follicular cells to newly formedpre dentin

Migration of HERS cells

Important proteins are

fibronectin-a mesenchymal chemo-

attractant

laminin- epithelial chemo attractant


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ATTACHMENT

Important factors

fibronectin

integrins

syndecan-proteoglycan

tenascin

BSP

OPN

CAP


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DIFFERENTIATION

Factors involved BMP-2,4,7

Epithelial proteins-amelogenins

Transcription factors-Runx-2(runt relatedtranscription factor also known as cbfa1)


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Matrix synthesis

After the initial root predentine formation anddetachment and disintegration of HERS

Formation of fringe fibers by follicular

fibroblast


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Predentineformation

Fragmentation ofHERS

Inductive signalfrom predentine

and enamelproteins to DF

Fringe fiberformation-DF

fibroblast

Inter digitations offringe fiber and

dentinal collagenfiber

matrix synthesisby AEFC forming

cementoblast

Fringe fiber getconnected to

developing Pdl

fiber

AEFC formationcontinues at the

rate of 5-

7micron/day

After mineralizationof mantle dentine

cementummineralization

procedes

AEFC FORMATION


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Root formation

reaches 2/3rdtooth enter

functional stage

CIFC forming

cementoblast extend cellprocess and depositcollagen matrix-multi

polar way and faster rate

Cementoblst getentrapped ascementocytes

Collagen fiberget connected

to dentinalcollagen

Haphazardlyarranged collagenfiber in CIFC get

arranged parallel toroot surface

Sometime matrixformation

become slow andunipolar resultingin AIFC formation

During the formationof CIFC and AIFC

some cementum getformed arounddeveloping Pdl

This results inthe formation of

CMFC

After mineralizationof mantle dentine

cementummineralization

procedes

CMFC,CIFC,AIFC FORMATION


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ACELLULAR AFIBRILLAR CEMENTUM FORMATION

- Believed to be development anomaly

- Focal disruption of reduced enamel epithelium- Contact of follicular cells to enamel

- Differentiation of cementoblast

- Consist of glycosaminoglycans and non fibrillar collagenouscomponent (does not have 64 nm periodicity).

INTERMEDIATE CEMENTUM- This (10n) noncellular amorphous layer near the cemento dential

junction

- Secreted by inner layer of HERS before it disintegrates.

- Main function is to seal the dential tubules

- Composed of enamelin protein

- More calcified than the adjacent cementum or dentin.

- It is usually not seen in human teeth.


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MINERALIZATION OF CEMENTUM

Hydroxyapatite Ca10(PO4)6(OH)2Structure - Crystal interior

- Crystal surface

- Hydration shell

This allows exchange of ions Role of formative cell in mineralization

- Create a micro environment that facilitate mineral ionhandling

- Secrete protein that stabilize Ca, Phosphate ions in bodyfluids and/or control their deposition

Secretary calcium binding phosphoprotein gene cluster.
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MECHANISMS OF MINERALIZATIONa. Homogenous nucleation - Booster theory

b. Hetrogenous nucleation - Matrix vesicle theory

Small membrane bound structure that buds off from the formative cells. Contain alkaline phosphatase, calcium adenotriphosphatase MMPs,

Proteoglycans, anionic phospholipids which can bind Ca and inorganic

phosphates .

These are unique to mineralizing situation.

Heterogeneous nucleation by other seeding agents Deposition of apatite crystal is catalysed by specific atomic groups associated

with surface holes, and pores of collagen fibrils. Non collagenous proteins

regulate this process.

Crystal growth influenced by non collagenous proteins which can bind

selectively to different surfaces of the crystal preventingfurther growth.

Pyrophosphate blocks the crystal growth

Alkaline phosphatase hydrolizes organic phosphate ions at an alkaline pH

- Provide phosphate ions at mineralization site.


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DEVELOPMENT OF PDL


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FIBROBLAST

Alveolar clade andcement clade of dentalfollicle Ectomesen

chymal origin Peri vascular

connective tissue

Dental papillawhichmigrate to dental follicleduring early

development HERS may also be a

source for pdl fibroblast

CELLS FOR NEUROVASCULARDEVELOPMENT

Vascular -Mesodermalorigin

Neural - Ectodermal(neuroectodermal)origin

STEM CELLS

PROGENITAR CELLS

Dental follicle HERS

Perivascular cells

CELLS INVOLVED


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EVIDENCES FOR HYPOTHESIZING

HERS CAN ALSO BE A SOURCE FOR

PDL FIBROBLAST

Pdl fibroblasts express cytokeratin 19

Presence of simplified desmosomes and

desmosomal proteins between Pdl fibroblast


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SIGNALING MOLECULES

Transcription factors

Homeobox genes Msx1, Msx2, Dlx1, Dlx2, Dlx3, Otlx2,Barx1Pax genes Pax9, Pax6

Lef1, Gli2/Gli3,Shh,Nfi-c

Growth factors

TGF1 & 2, BMP2, 3, 4, &7, Activin, FGF 4,8 & 9, Hepatocytegrowth factor, IGF1


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MATRIX SYNTHESIS

Pre-emergence

phase

Emergenceinto the oral

cavity

Firstocclusalcontact

Full occlusal

function


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PRINCIPLE FIBERS--STAGES OF DEVELOPMENT

A -Pre-emergence B-Emergennce

C-First occlusal contact D-Full occlusal function


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DIFFERENCE BETWEEN PRIMARY AND

SUCCEDANEOUS TEETH


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SUMMARY OF PRINCIPLE PDL FIBER DEVELOPMENT

fringe fibers,

unorganised

connective

tissue matrix

Growth of

collagen

fibers

Establishing

continuity

Intermediateplexus

PDL DEVELOPMENT OF OTHER


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PDL-DEVELOPMENT OF OTHER

COMPONENTS

Development of oxytalan fiberOnly form of elastic fiber in Pdl .Usually

form a three dimensional network around neuro

vascular elements

Develoment of ground substance

Non collagenous glycoproteins and

glycosaminoglycans Development of neurovascular elements

PERIODONTAL LIGAMENT AS A


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PERIODONTAL LIGAMENT AS A

MESENCHYME

FETAL TISSUE PDL

High rate of turnover Pdl collagen has high turnover rate

Collagen fibrils show unimodal size

distribution (25-50nm)

Pdl collagen fibrils show unimodal

distribution with diameter 40-50nm

Type collagen is significantly present Pdl contain around 20% type

collagen

Volume of ground substance is large Pdl also has more amount of ground

substance

Presence of immature elastin

fiber(oxytalan fiber)

Oxytalan fibers are present in Pdl

High cellularity Pdl shows high cellularity (fibroblast

occupy 45% of the tissue)


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What regulates the maintenance of Pdl as a non

mineralized tissue between two mineralized tissues ?

Clearly defined domains in the Pdl spaceCementum related domain

Pdl related domain

Alveolar bone related domain

Cell diversity and sub population in the Pdl Secretion of molecules which can regulate the extent of

mineralisation

Balance between BSP and osteopontinOsteopontin is morein Pdl

matrix Gla protein inhibit mineralisation

Type XII collagen

MSX2 - Suppress RunX2transcriptional activity-Preventsostogenic differentiation

ROLE OF PERIODONTAL LIGAMENT


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ROLE OF PERIODONTAL LIGAMENT

STEM CELLS


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DEVELOPMENT OF ALVEOLAR

BONE


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DEVELOPMENT OF JAWS

Maxilla and mandible develops from FirstBranchial arch(mandibular arch).

Arch has ectoderm endoderm and mesoderm

As neural crest cell migrate into the arch most ofthe mesenchymal tissue is replaced byectomesenchyme and first arch develops into

maxillary and mandibular prominence

This later develops into maxilla and mandible

DEVELOPMENT OF MANDIBLE


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DEVELOPMENT OF MANDIBLE

Meckles cartilage has only positional relationship

with developing mandible but makes no contributionto it

Neural part of mandible develops by the intramembranous ossification of the condensed

mesenchyme formed at the angle of division ofinferior alveolar nerve into mental and incisivebranches

Alveolar part develops as bony septa and bridgesseperaitng the individual tooth germs

Mascularpart develops with the development ofmuscular attachment

Three secondary cartilages (condylar, coronoid,symphyseal) also assist in further growth


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DEVELOPMENT OF MAXILLA

Develops by intramembranous ossification of themesenchyme of maxillary process of the 1starch

Center of ossification is closely associated with

the cartilage of nasal capsule

Primary ossification center is in the angle ofdivision of infra orbital nerve into anterior superior

alveolar nerve

Alveolar part forms around developing tooth

germs


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DEVELOPMENT OF ALVEOLAR BONE

Cells involved

Signaling molecules

Matrix synthesis

Mineralization


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CELLS INVOLVED

Osteoblast Dental follicle Ectomesen -

chyme

(Neural crest origin)

Osteoblast Mesodermal origin

Osteoclast Hematopoietic origin

D t i d OP


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OSTEOPROGENITAR

CELLS

Determined OPcells-Present in

bone marrow,endosteum,periosteum

Inducible OP cells mesenchymal cells of

other organs ,pericytes


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TYPES OF OSTEOGENIC CELLS Pre osteoblast-Appears like an inactive fibroblast

Osteoblast- Cuboidal to low columnar in shape

Abundent RER and golgibodies

Osteocytes- Stellate shape, Within the lacunae,Lesssynthetic and secretary activity,participate in blood Cahomeostasis,sense mechanical loading

Bone lining cells- Elongated cells,No synthetic activity,

Act as gatekeepers, protecting the bone surface fromosteoclasts, regulating the ionic composition of bonefluid, and regulating the initiation of new boneformation


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SIGNALING MOLECULES


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OTHER SIGNALING MOLECULES


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OTHER SIGNALING MOLECULES BMPs-

BMP2,3,4,6 and 7 have bone inductive activity. BMP 2 is chemoattractent to osteoblast. BMP 7 for

proliferation and differentiation

bFGF- increases the proliferation and differentiationof osteogenic cells

Colony stimulating factors- Granulocyte-MacrphageCSF stimulate osteoblst, Monocyte CSF stimulate

preosteoclast differentiation


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SIGNALING MOLECULES(CONTD)

PDGF- Chemotactic and mitogenic factor for

osteoblastic cells

IGF and TGF-- Stimulate osteoblast

Vit D

Glucocorticids

Retinoic acid

SIGNALLING MOLECULES&SIGNALLING PATHWAYS


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SIGNALLING MOLECULES&SIGNALLING PATHWAYS

DEVELOPMENTAL SEQUENCE OF


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Q

OSTEOBLAST (after differentiation)

1- Proliferative phase- Synthesis of matrix

2- Maturative phase- Making the matrix

competent for mineralization

3- Mineralisation phase


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MATRIX SYNTHESIS

The developing tooth germs are encased in rudimentary alveolar

processes in the maxilla and mandible (woven bone) which are formed

by neural crest-derived ectomesenchyme

Alveolar bone proper is formed during root development and is derived

from cells originating in the dental follicle

After the differentiation of follicle(alveolar clade) cells to osteoblast

they secrete the bone specific extracellular matrix (osteoid)

COMPOSITION OF


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EXTRACELLULAR MATRIX

COLLAGEN

Type- 1

Type- 3

NON-COLLAGENOUSPROTEINS

Osteocalsin,Bonesialoprotein

Osteopontin,Osteonectin,

Fibronectin

GAGS &PROTEOGLYCAN

GAG-Decorin andBiglycan

Proteoglycan-Condroitin sulphate,Heparin sulphate,

Hyluronan, Dermatinsulphate


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MINERALISATION

Homogenous nucleationBooster mechanism

Hetrogenous nucleation

Seeding mechanism-

Matrix vesicles

Collagen fibrils,Phosphoproteins

ROLE OF OSTEOBLAST IN


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MINERALIZATION

Production of primary vesicles- For the initiationof mineralization

Secretion of enzymes- control the mineralization

Regulate the number ions available for

mineralization


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ALVEOLAR BONE REMODELLING

By osteoblst & osteoclast

Woven bone -

Coarser ,lessmature, osteocytesare irregularlydispersed

Lamellar bone -

More regularfibrillar matrix andosteocytes withhaversiansystem(osteons)

which giveslamellar pattern


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DIFFERENCE BETWEEN PRIMARY


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AND SUCCEDANEOUS TEETH

PRIMARY TEETH & PERMENENT MOLAR


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Alveolar bone formation starts along with the root

formation and subsequent eruption of teeth

SUCCEDANEOUS TEETH

Initially they occupy the same osseous cavity with their

predecessor . As the predecessor erupts they occupy a

separate cavity lingual and apical to the primary teeth.

During eruption the roof of the bony cavity ,the root andalveolar housing of the primary teeth get resorbed and

succedaneous teeth occupy the vacant area .Only after

this alveolar bone deposition starts


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DEVELOPMENT OF GINGIVA

COMPONENTS OF GINGIVA


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GINGIVA

Epithelium

Oral epithelium

Sulcular epithelium

Junctional epithelium

Connectivetissue

Fibroblast

Gingival fibers

Non collagenous proteins

Neurovascular elements


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DEVELOPMENT OF GINGIVAL


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EPITHELIUM- CELLS INVOLVED

Outer Oralepithelium

Developed from oral mucosal epithelium

Ectodermal origin

Sulcularepithelium

Oral mucosal epithelium

Ectodermal origin

Junctionalepithelium

Reduced enamel epithelium-Enamel organ

Ectodermal origin

DEVELOPMENT OF JUNCTIONAL


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DEVELOPMENT OF JUNCTIONAL

EPITHELIUM

1. Formation of reduced enamel epithelium

2. Union of REE and Oral epithelium

3. As the tooth erupts REE is converted into JE

Changes during conversion

Cuboidal cells derived from ameloblast begin to flatten and align

parallel to tooth surface and take appearance of JE. Since these

cells which have lost capacity to divide get exfoliated at base of

sulcus and cells from stratum intermedium which has

proliferative capacity get transformed into JE


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PRIMARY EPITHELIAL ATTACHMENT


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PRIMARY EPITHELIAL ATTACHMENT

Attachment of reduced enamel epithelium to enamel of

unerupted crown

SECONDARY EPITHELIAL ATTACHMENT

After the conversion of REE to JE the attachment is

referred as secondary epithelial attachment

EPITHELIAL ATTACHMENT APPARATUS

Mediated by hemidesmosomes of DAT (Directly

Attached to Tooth) cells and internal basal lamina


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Characteristics Outer Oralepithelium

Sulcular epithelium Junctionalepithelium

Origin Oral epithelium Oral epithelium Reduced enamel


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Origin Oral epithelium Oral epithelium Reduced enamel

epithelium

Keratinization Parakeratinized

Sometimesorthokeratinized

Nonkeratinized Nonkeratinized

Stratification Well stratified Stratified but

granulosam and

corneum are absent

Poorly stratified

Proliferation Lesser proliferationamong three

Higher than OEE butlesser than JE

Higher proliferation

Permeability Not permeable to

water soluble

substances

Moderately

permeable

Highly permeable

Intercellular Space

Desmosomes&

tonofilaments

Narrowest

More than SE& JE

Narrower than JE

More than JE

Widest among three

Least among three

Retepegs Present Normally absent,

appears in

inflammation

Normally absent,

appears in

inflammation

DIFFERENT VIEWS ABOUT JE


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DIFFERENT VIEWS ABOUT JE

JE is an incompletely developed stratifiedsquamous epithelium

JE can be viewed as a structure that evolves

along a different pathway and produces thecomponents of epithelial attachment instead of

progressing into keratinized epithelium

This could be due to the functionally

different connective tissue which support JE

DEVELOPMENT OF CONNECTIVE


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TISSUE

Gingivalfibers

Dento gingival& transseptal- Dental follicle-Ecto mesenchyme- Neural crest

derived Other fibers- Oral mucosal connective tissue- Mesodermal or Neuralcrestal

Fibroblast

Peri follicular mesenchyme- Stomedial mesodermal or Neuralcrestal

Noncollagenou

s proteins

From fibroblast

Neurovasculat

ure

Neuro ectoderm and mesoderm respectively

TYPES & FUNCTIONS OF GINGIVAL FIBERS


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GINGIVAL FIBROBLASTS-

FEATURES


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FEATURES Functional subpopulations

Fibroblsts from marginal gingiva secretemore collagen and grondsubstance than attachedgingiva when exposed to diphenylhydantoin.

High active and low actie fibroblast whichrespond differently to drugs which causesenlargement

Fibroblast from tip of connective tissuepapilla retain fetal migratory phenotype and producemigration stimulatory factor whereas fibroblasts fromdeeper layers not.

Gingival fibroblasts do not come into contact with theroot during development like Pdl fibroblasts

VARIABILITY IN THE CONNECTIVE


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TISSUE COMPARTMENT

Connective tissue which support JE is

developmentally ,structurally and functionally

different from connective tissue which support

oral and sulcular epitheliumDevelopmental difference dental follicular origin

Structural difference Extensive vascular plexus

and inflammatory cells

Functional difference non permissive for epithelial

growth and differentiation

COMPOSITION OF EXTRACELLULAR

MATRIX OF GINGIVA


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Collagen

Type 1&3-laminapropria

Type 4- basementmembrane

Type 5-Aroud bloodvessels

Type 6- Micro fibrils

Noncollagenousproteins

Fibronectn,Osteonectin,

Tenascin, Elastin

Proteoglycans

Decorin

Biglycan

Versican Syndecan

GAGs

Hyaluronan

Heparan sulphate

Chondrotin sulphate Dermatan sulphate

MATRIX OF GINGIVA

DEVELOPMENT OF PERIODONTAL

VASCULATURE


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VASCULATURE

1staortic arch (mesodermal origin) is the artery of the 1stbranchial arch. This later undergoes partial regression andremnants become part of maxillary artery

Vasculogenesis

Clusters of blood vessls are formed around the tooh germ inthe dentl follicle which eventualy form the vasculature ofperiodontium

VEGF is the major growth factor involved

Mesoderm AngioblastAngioblastic

cordsAngiblastic

plexus


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DEVELOPMENT OF PERIODONTAL

INNERVATION


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INNERVATION Trigeminal nerve is the nerve of 1starch

Nerve fibers ramify and form arich plexus around thetooth germ in the dental follicle. This later developsinto the sensory supply of periodontium

Nerve growth factors -- neurotrophins, semaphorin,and glial cell line derived growth factor

Receptors Mechano receptors,nosiceptive receptors&sensory nerve endings

EctodermNeuro

ectodermNeurons

TO CONCLUDE


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Human periodontium is a specialised type of thecodontaltooth attachment

1starch derived epithelium & Neural crest derivedectomesenchyme are the essential components neededfor its development

Epithelial mesenchymal interaction is the key event in the

development Dental follicle proper is the major contributor for

periodontal development along with HERS

Periodontal development is entirely depends on tooth rootdeveloment

Homeobox genes, Cbfa 1, BMPs, and various othertranscription factors and growth factors play important rolein periodontal development

Genetically and phenotypically different


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subpopulations of fibroblasts and cementoblasts exist

in the periodontium

Periodontal ligament contains the precursor for all

these cells. Whether different precursors exist or

same precursor gives all types of cells is not clear

The exact signaling molecules and the pathwaysdirecting these cells to a particular cell type is still not

clear.

Better understanding in these aspects will help in

regenerative therapy

REFERENCES


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REFERENCES Ten catesoral histology 7thedition - Antonio Nanci

Orabansoral histology and embryology Edited byS.N.Bhaskar

Development function and evolution of teeth Mark F. Teaford

Essentials of oral histology and embryology James K. Avery

Biology of Periodontal tissues P.Mark Bartold, A. SampathNarayanan

Oral cells and tissues P.R.Garant

Fundamentals of periodontics 2ndedition-T.J. Wilson,

K.S.Kornman

Clinical peridontology and Implant dentistry -5th edition- Jan

Lindhe

REFERENCES


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REFERENCES

Periodontol 2000;2006(40):11-28

Periodontol 2000;2006(41):196-217

Periodontol2000;2000 (24)

Periodontol 2000;1999(19):8-20 Periodontol2000;1997(13)

J Dent Res 2005, 84(5):390-406

J Dent Res 2007, 86(7):594-599

J Periodont Res 2009;44:199-210

J Periodont Res 2009;44:81-87


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Documents

Development of Human Periodontium (1)