periodontium 1

Click to edit Master title style

Click to edit Master subtitle style

GOOD MORNING

Slide Title

• Make Effective Presentations• Using Awesome Backgrounds• Engage your Audience• Capture Audience Attention

OBJECTIVE

“What the mind doesn’t knowThe eyes doesn’t see”

LEARNER’S OBJECTIVES At the end of seminar Listener should be able revised with:

• Basics

• Normal features of Gingiva

• Correlation of clinical and microscopic features

• Differntiation of normal from diseased

Contents• Introduction to Periodontium• Some Basics

THE GINGIVA• Clinical features • Microscopic features • Correlation of clinical and microscopic

features • Gingival diseases in childhood

Introduction

It is defined as “those tissues supporting

and investing the tooth and consists of cementum, periodontal

ligament (PDL), bone lining the alveolus (socket),and that part of the gingiva facing the tooth”.

peri- "around"

-odon

s "toot

h”

periodontium

-"around the

tooth"

What is it ?• Foundation

• Complex system of tissues

• Cementum is part of it because with bone , it serves as a support for the fibres of PDL

Periodontium – A family

Gingiva AttachmentApparatus

• Proper functioningof the periodontium is achieved only through structuralintegrity and interaction between these various tissues.

• Together, these tissues form a specialized fibrous joint, agomphosis, the components of which are of ectomesenchymalorigin.

Periodontium

Oral mucosa•The term mucous membrane is used to describe the moist lining of the gastrointestinal tract, nasal passages, and other body cavities that communicate with the exterior. • In the oral cavity this lining is referred to as the oral mucous membrane, or oral mucosa.E

pithelium

Lamina

propria

Mucous Membr

ane

Epithelium

Laminapropria

Submucosa

Periosteum

Bone

Structure of oral mucosa

Papillary part

Tonofilaments

Hemidesmosomes

Collagen Fibrils

Anchoring Fibrils

Lamina DensaLamina Lucida

Basal Cell

Basement Membrane Complex•The interface between the connective

tissue and the epithelium

• Basement membranes promote differentiation. They also promote peripheral nerve regeneration and growth, and they tend to prevent metastases.

•The basal lamina is made up of a lamina lucida just below the epithelial cells and a lamina densa beyond the lamina lucida and adjacent to the connective tissue

ClassificationMasticatoryMucosa

• Gingiva

• Hard Palate

Lining or Reflecting Mucosa

• Lip,cheek• Soft palate• Alveolar mucosa• Floor of the mouth

Specialized mucosa

• Dorsum of tongue• Taste Buds

Hard palate

Lower lipGingiva

Palatinetonsil Pharyngeal

opening

Uvula

Anteriorfaucial pillar

Underside of tongue

Sublingual duct

Sublingual gland(under the skin)

Soft palate

Upper lip

Tongue

Anatomic locations occupied by the three main types of mucosa in the oral cavity.

Structure of Oral Epithelium• The epithelium of the oral mucous membrane is of the stratified squamous

variety.

• It may be keratinized (orthokeratinized or parakeratinized) or nonkeratinized.

•Both the keratinized and the non keratinized epithelium consists of two groups of cells namely the keratinocytes and the non keratinocytes.Epithelium

Keratinized

Keratinocytes

Non Keratinocytes

Non Keratinized

Keratinocytes

Non Keratinocytes

Cytokeratin

Melanocytes

Langerhan Cell

Merkel Cell

KERATINOCYTESThese are epidermal/epithelial cell that synthesizes keratin and its characteristic intermediate filament protein is cytokeratin.

PECULARITIES :• They show cell division.

• They undergo maturation and finally desquamate.

• They increase in volume in each successive layer from basal to superficial.

• The cells of each successive layer cover a larger area than do the cells of the layers immediately below.

Keratin•Keratin derives from Greek κερατίνη meaning "horn like"

• It is a family of fibrous structural protein

• It is the key structural material making up the outer layer of human skin. •It is the key structural component of hair and nails, and it provides the necessary strength and toughness for masticatory organs, such as the tongue and the hard palate.

Cytokeratin• Cytokeratins (CK) form the cytoskeleton of all epithelial cells.

• They are seen not only within the cell but also in cell contact areas like desmosomes.

• They are termed intermediate filaments as their diameter (7–11 nm) is intermediatebetween the larger microtubules (25 nm) and smaller microfilaments(4–6 nm).

Provide mechanical linkages

Distribute the forces over a wide area

Stress bearing structures within the epithelial cell

Maintains cell shape

Functions

Classification

Type I

Basic

(1-8)

•About 20 types of cytokeratin are recognized

• They always occur in pairs, of combination of type I with type II.

• In the absence of its pair, they are unstable and are susceptible to degradation by proteases.

Keratinization

Determination

Differentiation

Desquamation

Maturation

• Orthokeratinized epithelium, represents a complete stage of keratinization. (no nuclei in the stratum corneum and a well-defined stratum granulosum)

• Parakeratinized epithelium, represents an intermediate stage of keratinization. (the stratum corneum retains pyknotic nuclei, stratum granulosum)

• Nonkeratinized epithelium, no keratinization. (has neither granulosum nor corneum strata)

Degree of Keratinization

Keratinized layer

Prickle cell layer

Granular Layer

Basalcelllayer

Keratinized layer

Prickle cell layer

Basalcelllayer

Granular layer

Basal celllayer

Prickle cell layer

Intermediate layer

Superficial layer

There are smaller population (10%) of cells that do not possess cytokeratin filaments, hence they do not have the ability to keratinize.

These group of cells are termed nonkeratinocytes.

Unlike keratinocytes, nonkeratinocytes

Non Keratinocytes

Mitotic Activity

Maturative changes or Desquamate

Arranged in layers

Desmosomal attachments with adjacent keratinocytes

Non Keratinocytes

Melanocytes

Langerhan cells

Merkel Cells

Inflammatory Cells

• This cells differ in appearance from other epithelial cells in having a clear halo around their nuclei.

• Such cells have been termed clear cells, and what is obvious from ultrastructuraland immunochemical studies is that they represent a variety of cell types such as,

MelanocytesColour of

oral mucosaPigmentati

on

Melanin& Hb

Melanocytes

Long dendritic cell

Melanin as melanosomes

Melanin granules

Heavy pigmentation

Melanophages

Melanin pigmentation of the attached gingiva in a dark-skinned individual

• It is a dendritic cell sometimes seen above the basal layers of epidermis and oral epithelium.

• It is characterized by a small rod shaped granule, called the Birbeck granule.

• They appear in the epithelium at the same time as, or just before, the melanocytes, and they may be capable of limited division within the epithelium.

Langerhans Cells

• Unlike melanocytes, they move in and out of the epithelium, and their source is the bone marrow.

• They have an immunologic function, recognizing and processing antigenic material that enters the epithelium from the external environment and presenting it to T lymphocytes.

• Langerhans cells probably can migrate from epithelium to regional lymph nodes.

Langerhans Cells

Merkel Cells• The Merkel cell is situated in the basal layer of the oral epithelium and epidermis.

• It is not dendritic but possess keratin tonofilaments and occasional desmosomes linking it to adjacent cells so it does not always resemble the other clear cells in histologic sections.

• The characteristic feature of Merkel cells is the small membrane bound vesicles in the cytoplasm, sometimes situated adjacent to a nerve fiber associated with the cell.

Merkel Cells•These granules may liberate a transmitter substance across the synapse-like junction between the Merkel cell and the nerve fiber and thus trigger an impulse.

•This arrangement is in accord with neurophysiologic evidence suggesting that they are sensory and respond to touch.

Keratinized & Non Kertanized Epithelium

KeratinizedSurface layer

Granular Intermediate layer

Prickle Cell layer

Basal layer

KeratinizedSurface layer

GranularintermediateLayer

Prickle cellLayer

Basallayer

Surface layer

Prickle cell Layer

Basallayer

Intermediate layer

MembranecoatingGranules

Tonobrils

Tonofilaments

Glycogen

Kerato hyalinegranules

Some BasicsFEATURES CELL LAYER FEATURES CELL

LAYER

Cuboidal or columnar cells containing bundlesof tonofibrils and other cell organelles; site ofmost cell divisions.

Basal Cuboidal or columnar cells containing separate tonofilaments and other cell organelles; site of most cell divisions

Basal

Larger ovoid cells containing conspicuousTonofibril bundle membrane-coating granules appear in upper part of this layer.

Prickle/Spinosum Larger ovoid cells containingdispersed tonofilaments;membrane-coating granules appear in upper part of layer; filaments become numerous

Prickle/Spinosum

Keratinized Epithelium Non Keratinized Epithelium

Major Features of MaturationIn

Some BasicsFEATURES CELL

LAYERFEATURES CELL

LAYER

Flattened cells containing conspicuous keratohyaline granules associated with tonofibrils; membrane coating granules fuse with cell membrane in upper part; internal membrane thickening also occurs.

Granular Slightly flattened cells containing many dispersed tonofilaments and glycogen

Intermediate

Extremely flattened and dehydrated cells in which all organelles have been lost; cells filled only with packed fibrillar material; when pyknotic nuclei are retained, parakeratinization occurs

Keratinized Slightly flattened cells with dispersedfilaments and glycogen; fewer organelles are present, but nuclei persist

Superficial

Keratinized Epithelium Non Keratinized Epithelium

Major Features of MaturationIn

.

The Gingiva

.

“Gingiva is the part of the oral mucosa that covers the alveolar processes of the jaws and surrounds the necks of the teeth”. AAP 2001 : “The fibrous investing tissue, covered by keratinized epithelium, that immediately surrounds a tooth and is contiguous with its periodontal ligament and with the mucosal tissues of the mouth.”

DefinitionGlickman :

.

Clinical features In an adult, normal gingiva covers the alveolar bone and tooth root to a level

just coronal to CEJ.

Anatomical Divisions

Marginal Gingiva

Gingival Sulcus

Attached Gingiva

Interdental Gingiva

.

Marginal Gingiva•The marginal, or unattached, gingiva is the terminal edge or

border of the gingiva surrounding the teeth in collar like fashion.

•After completed tooth eruption, the free gingival margin is located on the enamel surface approximately 1.5-2 mm coronal to the CEJ.

.

It’s a shallow linear depression

It demarcates the free gingiva from adjacent attached gingiva.

It is positioned at a level corresponding to the level of cemento-enamel junction.

It usually it about 1 mm in wide and presents in only 50% of cases

Free gingival groove (FGG)

.

Gingival SulcusShallow crevice or space around the

tooth bounded by surface of tooth on one side and the epithelium lining the free margin of the gingiva on the other

It is roughly V –shaped.

Depth of Gingival Sulcus :Ideal conditions - zero.Clinically normal -2 – 3 mm. Histologic -1.8 mm with variations from 0 to 6 mm.

.

Attached Gingiva

•The portion of the gingiva that is firm, dense, stippled, and tightly bound to the underlying periosteum, tooth, and bone.

• Extends from the free gingival groove (coronally) to the mucogingival junction (apically) where it becomes continuous with the alveolar (lining) mucosa, except on the palate where there is no mucogingival junction.

• The width of AG is an important clinical parameter .

•It should not be confused with the width of the keratinized gingiva because the latter also includes the marginal gingiva.

.

Muco Gingival Junction

• It is the junction between the soft, fleshy mucus membrane of the oral cavity and the tough, collagen rich gingiva .

• The MGJ remains stationary throughout life

• Changes in the width of the attached gingiva are caused by modifications in the position of its coronal portion either by gingival overgrowth or by gingival recession) not in the position of MGJ.

Interdental Gingiva It occupies the gingival embrasure, which is

the space beneath the area of tooth contact. It can be pyramidal or have a "col" shape.

The shape depends on the :

• Contact point between the two adjoining teeth.

• The presence or absence of some degree of recession.

•The width of the approximal tooth surfaces

.

COL The posterior teeth,have approximal contact surfaces rather than contact point.

The interdental papilla has a shape in conformity with the outline of the interdental contact surfaces, a concavity hence a COL- is established in the posterior tooth. The COL region is covered by thin non-keratinized epithelium.

Col

Col

.

In Health & Disease

Microscopic Features Of Gingiva

Microscopic Features

Epithelium

Oral Sulcular Junctional

Connective Tissue

Collagen,fibers (60%) , fibroblasts

(5%), .

Vessels, nerves,matrix

(35%).

Gingival Epithelium• Historical Perspective - Only a physical barrier to infection and the underlying gingival attachment.

• Current Belief and Example -An active role in innate host defense.

Eg. Responds to bacteria by increased proliferation alteration of cell-signaling events changes in differentiation and cell death alteration of tissue homeostasis

•Types

Mechanical, chemical, water, and microbial barrierSignaling functions

Cell-cell attachmentsBasal laminaKeratin cytoskeleton

Keratinocyte

Langerhans cellsMelanocytes, Merkel cellsConstant RenewalReplacement of damaged cells

Cell-Cell AttachmentsDesmosomes, adherens junctionsTight junctions, gap junctions

Cell–Basal LaminaSynthesis of basal lamina componentsHemidesmosome

Functions and Features of Gingival Epithelium

Functions

Architectural Integrity

Major Cell Type

OtherCell Type

Constant Renewal

Cell - Cell attachments

Cell – Basal Lamina

Oral {Outer} Epithelium• The oral, or outer, epithelium covers the crest and outer surface of the marginal gingiva and the surface of the attached gingiva.

• On average, the oral epithelium is 0.2-0.3 mm in thickness.

Features:

•Represents the keratinized gingiva

•Extends from mucogingival junction to gingival margin

•It may be ortho- or parakeratinized, however the prevalent surface is parakeratinized.

Sulcular Epithelium• It lines the gingival sulcus and is thin,

nonkeratinized stratified squamous epithelium without rete pegs.

• Extent - from the coronal limit of the junctional epithelium to the crest of the gingival margin.

Potential to keratinize if........• If it is reflected and exposed to oral cavity.• The bacterial flora of sulcus is totally eliminated.

Sulcular Epithelium• The outer epithelium loses its keratinization

when placed in contact with tooth.

• The sulcular epithelium is extremely important because it may act as a semi permeable membrane.

• Through which injurious bacterial products pass into the gingival and tissue fluid from the gingiva seeps into the sulcus.

Junctional Epithelium• It is an epithelial collar that surrounds the tooth.

• Extent – CEJ---Bottom of gingival crevice• Length- 0.25 to 1.35• Coronally – 15-30 cells thick• Apically – Narrows to 1-3 cell thick

• These cells can be grouped in two strata: Basal layer- facing the connective tissue Suprabasal layer- extending to the tooth

surface.

• The JE attaches to afibrillar cementum present on the crown (usually restricted to an area within 1 mm of the CEJ) and root cementum in a similar manner.

• The attachment of the JE to the tooth is reinforced by the gingival fibers, which brace the marginal gingiva against the tooth surface. For this reason, the JE and the gingival fibers are considered a functional unit, referred to as the dentogingival unit

• The junctional epithelium is formed by the confluence of the oral epithelium and the reduced enamel epithelium during tooth eruption.

• After enamel formation is complete, the enamel is covered with reduced enamel epithelium (REE), which is attached to the tooth by a basal lamina and hemidesmosomes.

• When the tooth penetrates the oral mucosa, the REE unites with the oral epithelium and transforms into the JE.

Development

Development

• As the tooth erupts, this united epithelium condenses along the crown, and the ameloblasts, which form the inner layer of the REE, gradually become squamous epithelial cells.

• The transformation of the REE into a junctional epithelium proceeds in an apical direction without interrupting the attachment to the tooth.

• According to Schroeder and Listgarten,this process takes between 1 and 2 years

Development

Principal Features• The cells of JE immediately adjacent to the

tooth, attach themselves to the tooth by hemidesmosomes and basal lamina.

• JE is Unique in having to basal lamina 1. Internal 2. External

Hemidesmoso

mes

Basal lamina

Attachment

appratu

s

Junctional Epithelium

Enamel

Hemidesmosomes

Desmosomes

Gap Junction

Basal lamina (internal)

Basal lamina (external)

Lamina Propria

Principal Features• The JE has a high turnover rate (in the order

of 1-6 days) and its cells are exfoliated coronally into the gingival crevice.

• It is highest of any oral mucosa.

• Rapid shedding of cells effectively removes bacteria adhering to the epithelial cells and therefore is an important part of the antimicrobial defense mechanisms at the dentogingival junction.

Principal Features

Principal Features• Cells of JE together with fibroblast and

endothelial cells express ICAM – 1

• ICAM -1 helps in transmigration of neutrophils from adjacent capillaries and through junctional epithelium.

• Expresses – K 19 (absent from keratinized epithelium) K5 & K14 (stratification specific)

Conclusion• In conclusion, it is usually accepted that the JE exhibits several

unique structural and functional features that contribute to preventing pathogenic bacterial flora from colonizing the subgingival tooth surface.

1. JE is firmly attached to the tooth surface, forming an epithelial barrier against plaque bacteria.

2. It allows access of gingival fluid, inflammatory cells, and components of the immunologic host defense to the gingival margin.

3. Junctional epithelial cells exhibit rapid turnover, which contributes to the host-parasite equilibrium and rapid repair of damaged tissue.

4. The cells of the junctional epithelium have an endocytic capacity equal to that of macrophages and neutrophils and that this activity might be protective in nature.

Gingival fibers• The connective tissue of the marginal gingiva is densely

collagenous, containing a prominent system of collagen fiber bundles called the gingival fibers. They consist of type I collagen.

Functions: 1. To brace the marginal gingiva firmly against the tooth.

2. To provide the rigidity necessary to withstand the forces of mastication without being deflected away from the tooth surface.

3. To unite the free marginal gingiva with the cementum of the root and the adjacent attached gingiva.

Gingival fibers• They are arranged in three different

groups

Gingivodental

Circular

GingivalFibers

Transseptal

Gingivodental Group• The gingivodental fibers are those on the

facial, lingual, and interproximal surfaces. They are embedded in the cementum just beneath the epithelium at the base of the gingival sulcus.

• On the facial and lingual surfaces, they project from the cementum in fanlike conformation toward the crest and outer surface of the marginal gingiva, terminating short of the epithelium

Gingival fibers

GingivodentalGroup

Gingivodental Fibers• They also extend externally to the

periosteum of the facial and lingual alveolar bones, terminating in the attached gingiva or blending with the periosteum of the bone.

• Interproximally, the gingivodental fibers extend toward the crest of the interdental gingiva.

Circular Fibers• The circular fibers course through the

connective tissue of the marginal and interdental gingiva and encircle the tooth in ringlike fashion.

Circular Group

Transseptal Group• Located interproximally, the transseptal

fibers form horizontal bundles that extend between the cementum of approximating teeth into which they are embedded.

• They lie in the area between the epithelium at the base of the gingival sulcus and the crest of the interdental bone

• They are sometimes classified with the principal fibers of the periodontal ligament.

Transseptal Group

Transseptal Group

Gingival fibers• Page et al also have described

A group of semicircular fibers that attach at the proximal surface of a tooth, immediately below the cementoenamel junction, go around the facial or lingual marginal gingiva of the tooth, and attach on the other proximal surface of the same tooth

Gingival fibers

H – Transgingival G - Semicircular

Gingival fibers• Page et al also have described

A group of transgingival fibers that attach in the proximal surface of one tooth, traverse the interdental space diagonally, go around the facial or lingual surface of the adjacent tooth, again traverse diagonally the interdental space, and attach in the proximal surface of the next tooth.

• Supraperiosteal arterioles along the facial and lingual surfaces of the alveolar bone, from which capillaries extend along the sulcular epithelium and between the rete pegs of the external gingival surface.

• Occasional branches of the arterioles pass through the alveolar bone to the periodontal ligament or run over the crest of the alveolar bone

Blood Supply

Blood Supply• Vessels of the periodontal ligament, which

extend into the gingiva and anastomose with capillaries in the sulcus area.

• Arterioles, which emerge from the crest of the interdental septa and extend parallel to the crest of the bone to anastomose with vessels of the periodontal ligament, with capillaries in the gingival crevicular areas and vessels that run over the alveolar crest.

Lymphatics• Role of the lymphatic system in removing

excess fluids, cellularand protein debris, microorganisms, and other elements is important in controlling diffusion and the resolution of inflammatory processes.

• The lymphatic drainage of the gingiva brings in the lymphatics of the connective tissue papillae.

Lymphatics

• It progresses into the collecting network external to the periosteum of the alveolar process, then to the regional lymph nodes, particularly the submaxillary group.

• lymphatics just beneath the junctional epithelium extend into the periodontal ligament and accompany the blood vessels.

Nerve Supply• Neural elements are extensively distributed

throughout the gingival tissues.

• Within the gingival connective tissues, most nerve fibers are myelinated and are closely associated with the blood vessels.

• Gingival innervation is derived from fibers arising from nerves in the periodontal ligament and from the labial, buccal, and palatal nerves.

Nerve SupplyThe following nerve structures are present in

the connective tissue:• A meshwork of terminal argyrophilic fibers,

some of which extend into the epithelium

• Meissner-type tactile corpuscles

• Krause-type end bulbs, which are temperature receptors

• encapsulated spindles.

CORRELATION OF CLINICAL

AND MICROSCOPIC FEATURES

Color• The color of the attached and marginal

gingiva is generally described as “coral pink”

Produced by• vascular supply• the thickness and degree of keratinization of

the epithelium• presence of pigment-containing cells.

Size• The size of the gingiva corresponds with

the sum total of the bulk of cellular and intercellular elements and their vascular supply.

• Alteration in size is a common feature of gingival disease.

Contour The contour or shape of the gingiva varies

considerably and depends upon• shape of the teeth and their alignment in the

arch• location and size of the area of proximal

contact• the dimensions of the facial and lingual

gingival embrasures.

Contour• The marginal gingiva envelops the teeth in

collarlike fashion and follows a scalloped outline on the facial and lingual surfaces.

• It forms a straight line along teeth with relatively flat surfaces.

• Labio version - the normal arcuate contour is accentuated, and the gingiva is located farther apically.

• Lingual version - the gingiva is horizontal and thickened

Shape The shape of the interdental gingiva is

governed by the • contour of the proximal tooth surfaces • the location and shape of gingival

embrasures.

Consistency• It is firm and resilient and with the exception

of the movable free margin, tightly bound to the underlying bone.

• The collagenous nature of the lamina propria and its contiguity with the mucoperiosteum of the alveolar bone determine the firmness of the attached gingiva.

• The gingival fibers contribute to the firmness of the gingival margin.

Surface texture• The gingiva presents a textured surface

similar to an orange peel and is referred to as being stippled.

• Stippling is best viewed by drying gingiva.

• The attached gingiva is stippled; the marginal gingiva is not.

Surface texture• The attached gingiva is stippled; the

marginal gingiva is not.• Stippling is less prominent on lingual than

facial surfaces.

Stippling varies with age-• In infancy - Absent• Appears in some children at about 5 years of

age, increases until adulthood• Frequently begins to disappear in old age.

Surface texture• Microscopically, stippling is produced by

alternate rounded protuberances and depressions in the gingival surface.

• The papillary layer of the connective tissue projects into the elevations.

• The elevated and depressed areas are covered by stratified squamous epithelium.

Surface texture• Stippling is a form of adaptive specialization

or reinforcement for function.

• It is a feature of healthy gingiva, and reduction or loss of stippling is a common sign of gingival disease.

• When the gingiva is restored to health after treatment, the stippled appearance returns.

Position• The position of the gingiva refers to the level

at which the gingival margin is attached to the tooth.

• When the tooth erupts into the oral cavity, the margin and sulcus are at the tip of the crown,as eruption progresses, they are seen closer to the root.

• Continuous Tooth Eruption• Active Eruption• Passive Eruption

Passive Eruption



GOOD MORNING

• The tissues are pale pink but to a lesser degree than the attached gingiva of adults because the thinness of the keratinized layer causes the underlying vessels in children to be more visible.

• Stippling

• Gingival sulcular depth is shallower in the primary dentition than in the permanent dentition.

• Mean sulcus depth is 2.1 mm(±0.2mm), with an increase in depth from anterior to posterior.

PERIODONTIUM OF THEPRIMARY DENTITION

• The interdental gingiva is broad buccolingually and narrow mesiodistally, consistent with the morphology of the primary dentition.

• The attached gingiva varies in width anteroposteriorly, widest in the incisor area, narrowing over cuspid, and widening over molars

• The lingual attached gingiva shows an inverse relationship

• Interestingly, the JE is thicker in the primary dentition than in the permanent dentition, which is a phenomenon thought to reduce the permeability of the epithelium to bacterial toxins.

• The interdental gingiva is broad buccolingually & narrow mesiodistally, consistent with the morphology of the primary dentition.

• The attached gingiva varies in width anteroposteriorly, widest in the incisor area, narrowing over cuspid, and widening over molars.

• The lingual attached gingiva shows an inverse relationship.

• Radiographically, the lamina dura is prominent in the primary dentition, with a wider periodontal space than in the permanent dentition.

• The marrow spaces of the bone are larger, and the crests of the interdental bony septa are flat, with bony crests within 1 to2 mm of the CEJ.





Periodontium

ContentsPeriodontal Ligament• Introduction • Periodontal Fibers• Cellular Elements• Ground Substance• FunctionsCementum• Introduction • Classification• Thickness• Resorption & Repair

“Sometimes when I consider what tremendousconsequences come from little things…I am tempted to think….there are no little things”.

Periodontal LigamentIntroduction• It is dense fibrous connective tissue that

occupies the periodontal space between root of the teeth and the alveolus.

• It has continuity with gingiva, pulp.

• Average width - 0.25mm

• The space represents hour glass in shape

Periodontal fibers• The most important

elements of the periodontal ligament are the principal fibers, which are collagenous.

• They arranged in bundles, and follow a wavy course.

• Terminal portions of the principal fibers that insert into cementum and bone are termed Sharpey's fibers.

Collagen microfibrils, fibrils, fibers, and bundles

Principal FibersTransseptal

Alveolar crest

Horizontal Oblique

Apical Inter radicular

Trans septal

Alveolar Crest

Horizontal

Inter radicular

Oblique

Apical

Transseptal Group• They extend interproximally over the alveolar

bone crest and are embedded in the cementum of adjacent teeth.

• They are a remarkably constant finding and are reconstructed even after destruction of the alveolar bone has occurred in periodontal disease.

• These fibers may be considered as belonging to the gingiva because they do not have osseous attachment.

Alveolar crest Group• Alveolar crest fibers extend obliquely from

the cementum just beneath the JE to the alveolar crest.

• Fibers also run from the cementum over the alveolar crest and to the fibrous layer of the periosteum covering the alveolar bone.

Alveolar crest Group• They prevent the extrusion of the tooth and

resist lateral tooth movements.

• Their incision does not significantly increase tooth mobility unless significant attachment loss has occurred.

Horizontal Group• Horizontal fibers extend at right angles to

the long axis of the tooth from the cementum to the alveolar bone.

• They are the largest group in the PDL, extend from the cementum in a coronal direction obliquely to the bone.

• They bear the brunt of vertical masticatory stresses and transform them into tension on the alveolar bone.

Oblique Group

Apical Group• The apical fibers radiate in a rather irregular

fashion from the cementum to the bone at the apical region of the socket.

• They do not occur on incompletely formed

roots

• They are the largest group in the PDL, extend from the cementum in a coronal direction obliquely to the bone.

• They bear the brunt of vertical masticatory stresses and transform them into tension on the alveolar bone.

Interradicular Group

Connective tissue Cells

Epithelial rest cells

Immune system cells

Cells associated with neuro vascular elements

Cellular Elements

Connectivetissue cells

Fibroblast Cementoblast Osteoblast

Connective tissue cells

Fibroblast• Fibroblasts are the most common cells in the

PDL

• It appear as ovoid or elongated cells oriented along the principal fibers and exhibiting pseudopodia like processes.

• These cells synthesize collagen and also possess the capacity to phagocytose "old" collagen fibers and degrade them by enzyme hydrolysis.

Fibroblast• Thus collagen turnover appears to be

regulated by fibroblasts in a process of intracellular degradation of collagen not involving the action of collagenase.

• Phenotypically distinct and functionally different subpopulations of fibroblasts exist in the adult periodontal ligament.

EPITHELIAL CELLS• The epithelial cells in the PDL are remnants of

HERS, known as the epithelial cell rests of Malassez.

• The epithelial cells occur close to the cementum as clusters or strands of cells easily recognized in histologic sections because their nuclei generally stain deeply.

• Some believe they form a network around roots that possibly interconnects with the junctional epithelium

EPITHELIAL CELLS

UNDIFFERENTIATED MESENCHYMAL CELL

• It is an important cellular constituent of the PDL

• These cells have a perivascular location.

• They have been demonstrated to be a source of new cells for the PDL.

• Whether a single progenitor cell gives rise to daughter cells that differentiate into fibroblasts, osteoblasts, and cementoblasts or whether separate progenitors exist for each cell line is not known.

• The fact that new cells are being produced for the PDL while cells of the ligament are in a steady state means that this production of new cells must be balanced by migration of cells out of the ligament or cell death.

Ground substanceGround substance

Glycosaminoglycans

Proteoglycans

Hyaluronic acid

Glycoprotein

Fibronectin laminin

Ground substance

Functions

Physical Formative &Remodelling

Nutritional&

Sensory

Regulation of PDL width

Physical Functionsl. Provision of a soft tissue "casing" to protect the

vessels and nerves from injury by mechanical forces

2. Transmission of occlusal forces to the bone

3. Attachment of the teeth to the bone

4. Maintenance of the gingival tissues in their proper relationship to the teeth

5. Resistance to the impact of occlusal forces (shock absorption)

Physical Functions

CementumIntroduction• Cementum is the calcified avascular

mesenchymal tissue that forms the outer covering of the anatomic root.

• The two main types of cementum are acellular (primary) and cellular (secondary) cementum .

• Both consist of a calcified interfibrillar matrix and collagen fibrils.

• The two main sources of collagen fibers in cementum are Sharpey's (extrinsic) fibers, which are the embedded portion of the principal fibers of the periodontal ligament.

• They are formed by the fibroblasts

• Fibers that belong to the cementum matrix per se (intrinsic) and are produced by the cementoblasts.

• Organic matrix – Type – I (90%) Collagen Type – III (5%) Collagen

• The inorganic content of cementum (hydroxyapatite) is 45% to 50%

• It is less than that of bone (65%), enamel (97%), or dentin (70%).'

Acellular Cementum

• It is the first to be formed and covers approximately the cervical third or half of the root

• It does not contain cells.

Acellular Cementum

• This cementum is formed before the tooth reaches the occlusal plane, and its thickness ranges from 30 to 230µm

• Sharpey‘s fibers comprise most of the structure of acellular cementum,which has a principal role in supporting the tooth

Cellular Cementum

• It is formed after the tooth reaches the occlusal plane

• It is more irregular and contains cells (cementocytes)

• They are present in individual spaces (lacunae) that communicate with each other through a system of anastomosing canaliculi

Cellular Cementum

• Cellular cementum is less calcified than the acellular type

• Sharpey's fibers occupy a smaller portion of cellular cementum

Classification• Acellular afibrillar cementum (AAC)

• It contains neither cells nor extrinsic or intrinsic collagen fibers, apart from a mineralized ground substance.

• It is a product of cementoblasts and is found as coronal cementum in humans.

• It has a thickness of 1 to 15 µm.

Classification• Acellular extrinsic fiber cementum (AEFC)

• It is composed almost entirely of densely packed bundles of Sharpey's fibers and lacks cells.

• It is a product of fibroblasts and cementoblasts and is found in the cervical third of roots in humans but may extend further apically.

• Its thickness is between 30 and 230 µm.

Classification• Cellular mixed stratified cementum (CMSC) • It is composed of extrinsic (Sharpey's) and

intrinsic fibers and may contain cells. • It is a co-product of fibroblasts and

cementoblasts.

• It appears primarily in the apical third of the roots and apices and in furcation areas.

• Its thickness ranges from 100 to 1000 µm.

Classification• Cellular intrinsic fiber cementum (CIFC)• It contains cells but no extrinsic collagen

fibers. • It is formed by cementoblasts,

• Intermediate cementum is an ill-defined zone near the cementodentinal

• junction of certain teeth that appears• to contain cellular remnants of Hertwig's

sheath embedded• in calcified ground substance

Classification• Intermediate cementum

• It is an ill-defined zone near the cementodentinal junction of certain teeth that appears to contain cellular remnants of Hertwig's sheath embedded in calcified ground substance

Classification• Intermediate cementum

• It is an ill-defined zone near the cementodentinal junction of certain teeth that appears to contain cellular remnants of Hertwig's sheath embedded in calcified ground substance.

Thickness of cementum

• Cementum deposition is a continuous process that proceeds at varying rates throughout life.

• The thickness of cementum on the coronal half of the root varies from 16 to 60 µm, or about the thickness of a hair.

• It attains its greatest thickness (up to 150 to 200 µm) in the apical third and in the furcation areas.

Thickness of cementum• It is thicker in distal surfaces than in mesial

surfaces, probably because of functional stimulation from mesial drift over time.

• Between the ages of 11 and 70, the average thickness of the cementum increases threefold, with the greatest increase in the apical region.

• Average thicknesses of 95 µm at age 20 and 215µm at age 60 have been reported.

Abnormality in the Thickness

• Absence or paucity – Aplasia/ hypoplasia

• Excess – Hyperplasia / hypercementosis.

Hypercementosis• Because of considerable physiologic

variation in the thickness of cementum among different teeth in the same person and also among different persons, distinguishing between hypercementosis and physiologic thickening of cementum is sometimes difficult.

Hypercementosis• The term

hypercementosis refers to a prominent thickening of the cementum.

• It may be localized to one tooth or affect the entire dentition.

Hypercementosis• Hypercementosis occurs as a generalized

thickening of the cementum, with nodular enlargement of the apical third of the root.

• It also appears in the form of spike like (cemental spikes) created by either the coalescence of cementicles that adhere to the root or the calcification of periodontal fibers at the sites of insertion into the cementum

Hypercementosis• The etiology of hypercementosis varies and

is not completely understood.

• The spikelike type of hypercementosis generally results from excessive tension from orthodontic appliances or occlusal forces.

• The generalized type occurs in a variety of circumstances.

Hypercementosis• In teeth subject to low-grade periapical

irritation arisingfrom pulp disease, it is considered compensation for the destroyed fibrous attachment to the tooth.

• The cementum is deposited adjacent to the inflamed periapical tissue.

• Hypercementosis of the entire dentition may occur in patients with Paget's disease.

Resorption and Repair• Permanent teeth do not undergo physiologic

resorption as do primary teeth.

• However, the cementum of erupted as well as unerupted teeth is subject to resorptive changes that may be of microscopic proportion

• It may be sufficiently extensive to present a radiographically detectable alteration in the root contour.

Causes• Resorption may be caused by local or systemic

causes or may occur without apparent etiology. Local conditions • trauma from occlusion orthodontic movement• pressure from malaligned erupting teeth• cysts and tumors• teeth without functional antagonists• embedded teeth• replanted and transplanted teeth• periapical disease and periodontal disease.

CausesSystemic conditions • calcium deficiency,• hypothyroidism,• hereditary fibrous osteodystrophy,• Paget's disease.

Conclusion



GOOD MORNING

Periodontium - III





Periodontium

ContentsAlveolar process• Introduction• Composition• Structure• Vascular supply• Clinical Considerations• Conclusion• References

Introduction• The alveolar process is the portion of the maxilla

and mandible that forms and supports the tooth sockets (alveoli).

• It forms when the tooth erupts to provide the osseous attachment to the forming PDL.

• It disappears gradually after the tooth is lost.

• Tooth dependent bony structure.

Composition

Inorganic Matter

• Calcium & phosphate• Hydroxyl, carbonate, citrate• Trace amount of sodium, magnesium,

flourine

Organic Matrix (osteoid)

• Collagen type I• Non collagenous protein

Inorganic matter• The inorganic part of bone is made of bone minerals.

• The mineral component is composed of hydroxyapatite crystals, with carbonate content and low Ca/P ratio than the pure hydroxyapatite.

• Small amounts of calcium phosphate are also present.

• Bone crystals are in the form of thin plates or leaflike structures.

• They are packed closely with long axis nearly parallel to collagen fibrils axis.

Inorganic matter• The narrow gaps between the crystals contain

associated water and organic macromolecules.

• The ions present are calcium phosphate, hydroxyl and carbonate

• Citrate, magnesium, sodium, potassium, fluoride, iron, zinc, copper, aluminum, lead, strontium, silicon and boron are present in small quantities.

Organic matrix• Collagen is the major organic component in

mineralized bone tissues.

• Type I collagen (> 95%) is the principal collagen in mineralized bone and, together with type V collagen (< 5%), forms heterotypic fiber bundles

• This provide the basic structural integrity of connective tissues.

• The elasticity of collagen imparts resiliency to the tissue and helps to resist fractures.

Collagens

AlveolarBone

•Type I•Type III•Type V•Type XII

Sharpey’s

fibers

•Type I•Type III

Non Collagenous Proteins

Matrix Gla protein

Osteocalcin

Osteocalcin• It is the first noncollagenous protein to be

recognized and represents less than 15% of the noncollagenous bone protein.

• Also known as bone Gla protein as it contains the amino acid γ-carboxy glutamic acid.

• It is a glycoprotein secreted by osteoblasts and is regulated by vitamin D3 and parathyroid hormone.

Osteopontin & bone sialoprotein

SimilaritiesHeavily glycosylated and phosphorylated

Expression of both is stimulated by TGF-ᴃ & glucocorticoids

Sialoprotein Osteopontin

Glutamic acid is predominant Aspartate is predominant

Restricted to mineralizing tissue Generalized distribution

Function in initiation of mineral crystal formation

Potent inhibitor of hydroxypatite crystal growth

Transcription is supressed by vitamin D3

Transcription is upgraded by by vitamin D3

Differences

Osteonectin• It comprises about 25% of noncollagenous proteins.

• It is bound to collagen and hydroxyapatite crystals.

• It is a secreted calcium binding glycoprotein

• It interacts with extracellular matrix molecules. Plays a role in:• the regulation of cell adhesion, proliferation• modulation of cytokine activity, • in initiating hydroxyapatite crystal formation.

Proteoglycans• There are three types present

1. A large chondroitin sulfate proteoglycan2. Biglycan and decorin (chondroitin sulfate proteoglycan I and II respectively)3. A small chondroitin sulfate proteoglycan

• Decorin and biglycan comprise < 10% of the noncollagenous proteins in bone, but this decreases with maturation of bone.

Proteoglycans Biglycan • It is more prominent in developing bone and has

been mineralized to pericellular areas. • It’s precise function is unknown, but similar to

decorin, it can bind TGF-β and extracellular matrix macromolecules, including collagen, and thereby regulate fibrillogenesis.

ProteoglycansDecorin• It binds mainly within the gap region of collagen

fibrils and decorates the fibril surface.

• The primary calcification in bones is reported to follow removal of decorin and fusion of collagen fibrils

Cells

Osteoblasts

Osteoclasts

Osteocytes

Osteoblast• Mononucleated

• Synthesis and secrete macro molecular organic constituents of bone matrix

• Derived from osteo progenitor cells of mesenchymal origin

Osteoblast

Osteocyte

Osteoclast

Functions• Formation of new bone

• Regulation of bone remodeling

• Mineral metabolism

• Role in mineralization of osteoid

• Secretes type I collagen

Functions• Also secrete non collagenous protein in small

amount

• Receptor of various hormone including PTH, vitamin D3,estrogen and glucocorticoids

• Recognizes the resorptive signal and transmit it to the osteoclast

Osteocytes• Osteoblasts produce the

extracellular matrix, osteoid.

• As they form the matrix they get entrapped within the matrix they secrete, and are called osteocytes.

• The number of osteoblasts

that become osteocytes, depends on the rapidity of bone formation.

Osteocyte

Osteoblast

Osteoid

Osteocytes• Within the bone matrix, the osteocyte

reduces in size, creating a space around it, called the osteocytic lacuna.

• The lacunae can appear ovoid or flattened.

• Narrow extensions of these lacunae form channels called canaliculi.

Osteocytes• The canaliculi penetrate the bone matrix

and permit diffusion of nutrients, gases and waste products between osteocytes and blood vessels.

• Osteocytes also sense the changes in environment and send signals that affect response of other cells involved in bone remodeling.

Osteocytes• This interconnecting system maintains the

bone integrity and bone vitality.

• Failure of the interconnecting system between osteocytes and osteoblasts leads to sclerosis and death of bone.

Osteoclast• The word “osteoclast” is derived from the

Greek words for “bone and broken”. • It lies in resorption bays called Howship’s

lacunae.

• Variable in shape

• 40-100µm in diameter

• 15-20 packed nuclei

Osteoclast

Structure1. An external plate of

cortical bone

2. The inner socket wall of thin, compact bone called the alveolar bone proper, which is seen as the lamina dura in radiographs and is formed by the cancellous bone.

Structure3. Cancellous trabeculae, between these two

compact layers, which act as supporting alveolar bone.

• The interdental septum consists of cancellous supporting bone enclosed within a compact border

Relative proportions of cancellous bone and compact bone in a longitudinal faciolingual section

Socket Wall• The socket wall consists of dense,

lamellated bone and bundle bone.

• Bundle bone is the term given to bone adjacent to the PDL that contains a great number of Sharpey's fibers.

Socket WallCharacteristics:• thin lamellae arranged in layers parallel to

the root

• intervening appositional lines.

• Bundle bone is localized within the alveolar bone proper.

Bone Marrow• In the embryo and newborn, the cavities of all

bones are occupied by red hematopoietic marrow.

• The red marrow gradually undergoes a physiologic change to the fatty or yellow inactive type of marrow.

• In the adult, the marrow of the jaw is normally of the fatty type.

• Red marrow is found in the ribs, sternum,vertebrae, skull, and humerus.

Bone Marrow• However, foci of red bone marrow are occasionally

seen in the jaws, often accompanied by resorption of bony trabeculae.

Common locations are• the maxillary tuberosity,• the maxillary and mandibular molar and premolar areas.• mandibular symphysis and ramus angle

• It may be visible radiographically as zones of radiolucency.

Periosteum & Endosteum

Periosteum:• Tissue covering the outer surface of bone.• Inner layer - osteoblasts surrounded by

osteoprogenitor cells.• Outer layer – blood vessels and nerves, collagen

fibers and fibroblasts.

Endosteum:• Tissue lining the internal bone cavities.• Composed of single layer of osteoblasts and small

layer of connective tissue.• Inner layer – osteogenic• Outer layer- fibrous layer

Vascular Supply• The blood supply to the supporting structures of

the tooth is derived from the inferior and superior alveolar arteries to the mandible and maxilla respectively.

It reaches the periodontal ligament from three sources:

• apical vessels, • penetrating vessels from the alveolar bone,• and anastomosing vessels from the gingva

Vascular Supply• The vascular supply to the bone enters the

interdental septa through nutrient canals together with veins, nerves, and lymphatics.

• Dental arterioles, which also branch off the alveolar arteries, send tributaries through the PDL, and some small branches enter the marrow spaces of the bone through the perforations in the cribriform plate.

• Small vessels emanating from the facial and lingual compact bone also enter the marrow and spongy bone.

Lymphatic drainage

• Lymphatics supplement venous drainage system.

• Those draining the region just beneath the junctional epithelium pass into the periodontal ligament and accompany the blood vessels into the periapical region

• From PDL, lymphatic channels pass through alveolar bone to inferior dental canal in mandible or infraorbital canal in the maxilla then to submaxillary lymph nodes.

Clinical Considerations

Orthodontic tooth Movement• Bone, although one of the hardest tissues of the

human body, is biologically a highly plastic tissue. • Where bone is covered by a vascularized

connective tissue. • It is exceedingly sensitive to pressure, whereas

tension acts generally as a stimulus to the production of new bone.

Clinical Considerations

Orthodontic tooth Movement• It is this biologic plasticity that enables the

orthodontist to move teeth without disrupting their relations to the alveolar bone.

• Bone is resorbed on the side of pressure and apposed on the side of tension,thus the entire alveolus is allowed to shift with the tooth.

Increase in the level of c Amp on pressure side

At the site of compression, osteoclast proliferate and there is initial resoprtion of bone

At sites of tension, osteoblasts are activated to produce osteoid that subsequently mineralizes to form new bone.

• Fusion of the cementum and alveolar bone with obliteration of the periodontal ligament is termed ankylosis.

• Ankylosis occurs in teeth with cemental resorption, which suggests that it may represent a form of abnormal repair.

• Ankylosis results in resorption of the root and its gradual replacement by bone tissue.

• For this reason, reimplanted teeth that ankylose will lose their roots after 4 to 5 years and exfoliate.

Ankylosis

• In healthy patients, abundant PDL fibroblasts block osteogenesis within the periodontium by releasing locally acting regulators, such as cytokines and growth factors, thereby maintaining separation of tooth root from alveolar bone.

• Necrosis of the periodontal ligament’s cellular elements by desiccation, crushing or mechanical damage, as in severe luxation injury, disrupts this normal homeostatic mechanism.

Ankylosis in replantation

• Ankylosis is established not only via inflammatory-mediated and mechanical alterations in the periodontal ligament, but also because insufficient functional cellular elements survive to suppress osteogenic activity.

• This disruption allows growth of bone across the periodontal ligament and ankylosis

• Ankylosis is most common following delayed replantation or severe intrusion .


• With the loss of periodontal ligament homeostasis and subsequent ankylosis, replacement resorption ensues.

• The root is gradually replaced by bone as part of normal turnover of the body’s skeletal mass.

• In the young child, the combined effect of a higher metabolic rate that promotes replacement resorption and the lack of root mass in the immature tooth produces tooth loss within a few years.


Ankylosis• When titanium implants are placed in the

jaw, healing results in bone formed in direct apposition to the implant without any intervening connective tissue.

• This may be interpreted as a form of ankylosis.

• Because resorption of the metallic implant cannot occur, the implant remains indefinitely "ankylosed" to the bone.

Resorption• The bone resorption is almost universal, occurs more

frequently in posterior teeth, is usually symmetrical

• It occurs in episodic spurts, is both of the horizontal and vertical type (i.e., occurs from the gingival and tooth side, respectively)

• It is intimately related to bacterial plaque and pocket formation.

• Endotoxins produced by the gram negative bacteria of the plaque lead to an increase in cAMP, which increases the osteoclastic activity.

• Isolated areas in which the root is denuded of bone and the root surface is covered only by periosteum and overlying gingiva are termed fenestrations.

• In these instances the marginal bone is intact.• When the denuded areas extend through the

marginal bone, the defect is called a dehiscence

Fenestrations and Dehiscences

Fate of PDL of primary tooth

• In case of the periodontal ligament it has been demonstrated that apoptotic cell death is involved.

• This form of cell death involves

shrinkage of the cells so that they can be phagocytosed by neighboring cells.

• Apoptotic cell death is a normal feature of embryogenesis and is programed so that cells die at specific times to permit orderly development.

Biologic width• The natural seal that develops around both,

protecting the alveolar bone from infection and disease, is known as the biologic width.

• The biological width is defined as the dimension of the soft tissue, which is attached to the portion of the tooth coronal to the crest of the alveolar bone.

• “Biologic Width” term is coined by D.Walter Cohen .

Biologic width(a) Histological sulcus

(0.69 mm)(b) Epithelial

attachment (0.97mm)

(c) Connective tissue attachment

(1.07 mm) (d) Biologic width (b+c)

Conclusion• The normal periodontium is a unique and complex

dynamic structure providing support necessary to maintain teeth in function

• Proper functioning of the periodontium is achieved only through structural integrity and interaction between the various tissues which are its components.

• Certain features of gingiva and periodontium exclusively seen in children may be normal findings and unrelated to pathology.

Previously Asked questionsSAQs

• Enumerate various gingival and periodontal diseases in children and discuss clinical features and management of ANUG. (2003)

• Prevalence of periodontal diseases in India.(2004)

• Scorbutic gingivitis (2006)

• Gingival diseases in children and its management. (2008)

References1. Orban’s Oral histology And Embryology, 13th

edition2. Carranza’s Clinical Periodontology, 10th edition3. Ten Cate’s Oral Histology, 8th edition4. Oral Anatomy, Histology and Embryology, 4th

edition : Berkovitz B., Holland G., Moxham B.5. Oral Development And Histology, 3rd edition;

James Avery6. Shafer’ Textbook of Oral Pathology, 5th edition

periodontium 1

Health & Medicine