Perio 2 - Gingiva and PDL Part 2

7/28/2019 Perio 2 - Gingiva and PDL Part 2

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cont....

Other cell types within gingival epithelium:

Langerhans cells: modified monocytes playing a

role in immunity

Merkel cells: contain nerve endings

Melanocytes: responsible for production of

melanin

Anatomic Parts of Epithelium

these parts of epithelium play different functions,

notice the pic beside it was divided into 3 parts: oral

pithelium OE, sulcular epithelium SE and Junctional

epithelium.

the epithelium covering the gingiva from the buccal

aspect up to the crest of the gingiva facing the oral

cavity.

The epithelial ridges of the OE extend down into the

underlying connective tissue in a wavy manner, to be

stronger to give support, while others are almost

straight. A dense network of collagen fibers tightly

anchors the epithelium.

Gingival Crevicular Fluid (GCF)

it is fluid in the gingival sulcus we call it sulcular fluid, it helps in immunity

protection, In healthy or normal states the sulcus is very thin because the free

gingiva is almost touching the tooth so the GCF's volume is small. while in the

cases of gingivitis and peritonitis you know that permeability of the vesselsincreases and more migration of fluids happen so with inflammation, its flow

increases and composition changes.

Source: diffusion of fluids of plasma through JE & SE.

Functions:

Cleansing; although it is very small amount but the production is continuous it's


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Connective Tissueas you know it lies beneath epithelium, the attachment

between the epithelium and the connective tissue is the

basement membrane.

Gingival CT is largely fibrous, the major component is

Collagen (different types 1-12) , it has Cellular component

and ground substance and Contains the vascular,

lymphatic and nerve supply/drainage to/ from the gingival

tissues.

Arrangement of Gingival Fibers

they are arranged in groups:DGdentogingival fibers ; fibers attaches the

tooth to the gingival tissue.

Circular fibers , like rods go around the teeth in a

cross section.

AGalveologingival fibers ; from the alveolar

bone to the gingiva.

PGperiostogingival fibers; do not go deep intothe bone.

Transseptal fibers between teeth.

Functions of Gingival Fibers

y marginal gingiva to the tooth

Rigidity and resistant against mastication without

deflection

with cementum and attached gingiva

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End of the first part

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The periodontium

we talked about the gingiva the gingival

ligaments in general are not mineralized, we willtalk about the PDL:

The Periodontal Ligament

it is The connective tissue that

surrounds the root and attaches it to the

alveolar bone basically and some parts of

the gingival tissue as well, it is Continuous

with connective tissues of gingiva and

communicates with marrow spaces in

bone.

although it as a structure physically is

very small and thin ,but functionally

important most of the functions is related

to the PDL. periodontitis is pathological

inflammation of the PDL.

we know that teeth are vital tissue suspended into the alveolar bone, they are incontinuous movement , so the PDL Subjected to continuous mechanical loading.

PDL has a High turnover rate or regeneration, if it's lowered we know that there

is a problem, this reduction will lead to lower PDL height and lower the self

healing of the tissues.

The Periodontal Ligament Composed of:

Fibers

Cells : floating in the air without relation to each otherExtra Cellular Matrix ECM : contain cells floating in the air without relation to

each other, imbedded into a matrix containing proteins.

Nerves : PDL's function is shock absorption and feeling , for example itchy

feeling when attacked by micro organisms, so it's very important bcz it tells you

that there is something wrong.


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blood & lymphatic vessels

The Periodontal Ligament Fibers:

the most important are the principal fibers , which we will focus on,

Other fibres are immature elastic fibres: Oxytalan and Eluanin

Indifferent fiber plexus

Principal fibres

composed from type I and III collagen fibrils which will

form fibers, type I collagen: fibers are arranged inbundles, they Follow a wavy course to be able to

withstand tensile strength to be stretchable.

Terminal portions inserted into cementum and bone:

Sharpeys fibres (part of the periodontal ligament that

is imbedded into the alveolar bone and cementum in

both sides , they get mineralized with bone and

cementum) notice the pic beside :P

Fibers

what makes PDL strong to function? Mechanical strength

of PDL is derived from 1- the molecular structure oftype I

collagen AND 2- its arrangement into fibers.

the Tensile strength of PDL larger than the steel, it

withstand 100 kg forced by the masticatory muscles. e.g.

we will learn how to deal with epileptic patients one of

the most important things never let ur finger to be

between his teeth, he could cut ur finger off! or they

could cut their tongue, so it's very strong force needs high

tensile strength structure.


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, parallel lines of

fibers crossing each other

Groups of fibres

remember that it is one functional unite but under

the histological study we see the direction of them

slightly different, every one responsible to prevent

different movement of the tooth.

Transseptal group

Connect adjacent teeth

Alveolar crest group

Resist extrusion, lateral movements

Horizontal group

Resist lateral movements

Oblique group

Receive the bulk of vertical forces

Apical groupResist intrusion & extrusion

Inter-radicular group

Furcation areas of multi-rooted teeth

So if there is force presses on the tooth very group will work and switch off or

absorb it then goes back to its position.

How do these Groups of fibres be formed? "go to the book to read about it"

basically The PDL is derived from ectomesenchymal cells of the dental follicle

e are

mineralised.


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that are packed together to form fibrils. Fibrils aggregate together to form fibres,

and fibres aggregate to form bundles. Collagen fibrils are cross-striated.

Principal Fibres, parts of the gollagenfibers in the pic beside. --> microfibril

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Perio 2 - Gingiva and PDL Part 2