ultrastructure of gingiva

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BY ARINEITWE DEUS BDSV ULTRASTRUCTURE OF GINGIVA

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Page 1: Ultrastructure of gingiva

BY

ARINEITWE DEUS

BDSV

ULTRASTRUCTURE OF GINGIVA

Page 2: Ultrastructure of gingiva

GINGIVA

Part of the oral mucosa that covers alveolar

process of the jaws and surrounds the neck of

teeth.

It is anatomically divided into three parts;

marginal gingiva

Attached gingiva

Interdental gingiva

Page 3: Ultrastructure of gingiva

GINGIVA

Page 4: Ultrastructure of gingiva

MARGINAL GINGIVA

Is the terminal edge or border of the gingiva

surrounding the teeth in collar-like fashion.

Its demarcated from attached gingiva by free

gingival groove in 50% cases.

Its usually about 1mm wide

It forms soft tissue wall of gingival sulcus

It can be separated from tooth surface with

periodontal probe.

Page 5: Ultrastructure of gingiva

ATTACHED GINGIVA

Is continous with marginal gingiva

Its firm, resilient, and tightly bound to underlying

periosteum of alveolar bone

Facial aspect of attached gingiva extends to

alveolar mucosa as demarcated by mucogingival

junction.

Width of attached gingiva is clinical parameter

Width of attached gingiva is greatest in incisor

region and least in first premolar area.

Page 6: Ultrastructure of gingiva

INTERDENTAL GINGIVA

Occupies the gingival embrasure

Shape of interdental gingiva depends on the

contact point between adjacent teeth and

presence or absence of recesion.

It can be pyramidal or ‘col’ shaped

In pyramidal shape, the tip of papilla is located

immediately beneath the contact point.

In col shape, a valley like depression connects a

facial and lingual papilla.

Page 7: Ultrastructure of gingiva

INTEDENTAL GINGIVA

Page 8: Ultrastructure of gingiva

SHAPE OF INTERDENTAL

GINGIVA

Facial and lingual surfaces are tapered toward

the interproximal contact area

Mesial and distal surfaces are slightly concave

Lateral borders are formed by continuation of

marginal gingiva from adjacent teeth

If a diastema is present, gingiva is firmly bound

over the interdental bone and forms a smooth,

rounded surface without interdental papilla

Page 9: Ultrastructure of gingiva

INTERDENTAL GINGIVA

Page 10: Ultrastructure of gingiva

MICROSCOPIC FEATURES

Gingiva can be divided into two main parts

Stratified squamous epithelium

Connective tissue core

Gingival epithelium is functionally and

morphologically classified into three parts.

Oral/outer epithelium

Sulcular epithelium

Junctional epithelium

Page 11: Ultrastructure of gingiva

GINGIVAL EPITHELIUM

Principal cells are keratinocytes

Others are clear cells or nonkeratinocytes eg

langerhan cells, merkels cells, and melanocytes

Main function of gingival epithelium is to protect

the deep structures. This is achieved by

proliferation and differentiation.

Proliferation of keratinocytes takes place by

mitosis in the basal layer and less frequently

suprabasal layer, where a small portion of cells

remain proliferative while a larger portion migrate

to the surface.

Page 12: Ultrastructure of gingiva

GINGIVAL EPITHELIUM

Differentiation involves the process of

keratinisation, which consists of a sequence of

biochemical and morphologic events that occur in

the cells as it migrates from basal layer.

Morphologic events include;

Proliferative flattening of cells

Increasing prevalence of tonofilaments and

intercellular junction

Production of keratohyaline granules

Dissapearance of the nucleus

Page 13: Ultrastructure of gingiva

GINGIVAL EPITHELIUM

Page 14: Ultrastructure of gingiva

KERATINIZATION

Complete keratinization leads to production of

orthokeratinized epithelium similar to that of the

skin, with no nuclei in stratum corneum, and a

well defined stratum granulosum.

Only some areas of the outer gingival epithelium

are orthokeratinized, others are parakeratized or

non keratinized.

These areas can progress to maturity or

dedifferentiate under physiologic or pathologic

conditions.

Page 15: Ultrastructure of gingiva

PARAKERATINIZED EPITHELIA

Stratum corneum retains pyknotic nuclei

Keratohyalin granules are dispersed, not giving

rise to a stratum granulosum.

Non keratinized epithelium

Cytokeratins are major component

No granulosum or corneum strata

Superficial cells have visible nuclei

Page 16: Ultrastructure of gingiva

ELECTRON MICROSCOPE

Reveals that keratocytes are interconnected by

structures on the cell periphery called

desmosomes

Desmosomes have a typical structure consisting

of two dense attachement plaques into which

tonofibrils insert

Tonofilaments radiate in brush like fashion from

attachement plaques into cytoplasm of cells.

Page 17: Ultrastructure of gingiva

TIGHT JUNCTIONS/ZONAE

OCCLUDENS

Less frequently observed forms of epithelial cell

connections

Membranes of adjoining cells are believed to be

fused

These structures allow ions and small molecules

to pass from one cell to another.

Page 18: Ultrastructure of gingiva

CYTOPLASMIC ORGANELLE

CONCENTRATION

Varies among different epithelial strata

Mitochondria more numerousin deeper strata

Succinic dehydrogenase, NAD, cytochrome

oxidase, and other mitochondrial enzymes

revealed a more active tricarboxylic cyclein basal

and parabasal cells; where proximity of blood

vessels facilitate energy production through

aerobic glycolysis.

Enzymes of pentose shunt such as G6Pase

increase their activity towards the surface. This

pathway produces RNA used in synthesis of

keratin proteins.

Page 19: Ultrastructure of gingiva

KERATINOSOMES/ODLAND

BODIES

Are modified lysosomes

Found in uppermost cells of strataspinosum

Are numerous dense granules

Contain large amounts of acid phosphatase, an

enzyme involved in the destruction of organelle

menbranes, which usually occur between

granulosum and corneum strata and during

intercellular cementation of cornified cells.

Page 20: Ultrastructure of gingiva

NONKERATOCYTE CELLS

melanocytes: for production of melanin

Langerhans cells: have phagocytic activity

Merkels cells: tactile perceptors

Page 21: Ultrastructure of gingiva

BASAL LAMINA

Connects epithelium to underlying connective

tissue

Consists of lamina lucida and lamina densa.

Hemidesmosomes of the basal lamina tourch the

lamina lucida, which is mainly composed of

glycoprotein laminin.

Lamina densa is composed of type IV collagen.

Page 22: Ultrastructure of gingiva

STRUCTURAL AND METABOLIC X-

TICS OF DIFFERENT AREAS OF

GINGIVAL EPITHELIUM

ORAL/ OUTER EPITHELIUM

Covers the crest and outer surface of the

marginal gingiva, and the surface of attached

gingiva.

It is keratinised, pparakeratinized, or in

combination

Prevalent surface is however parakeratinized

Page 23: Ultrastructure of gingiva

OUTER EPITHELIUM

Degree of gingival keratinization diminishes with

age and onset of menopause, but not related to

phases of menstrual cycle.

Keratins k1, k2, and k10-k12, which are specific

of epidermal type differentiation are expressed

with high intensity in orthokeratinized areas

K5 and k14, stratification specific cytokeratins are

also present

Parakeratinized areas express k19, which is

usually absent from orthokerakinized areas.

Page 24: Ultrastructure of gingiva

SULCULAR EPITHELIUM

Lines the gingival sulcus

Thin nonkeratinized stratified squamous

epithelium without rete pegs

Extends from coronal limit of junctional epithelium

to the crest of gingival margin

Lacks granulosum and corneum strata, and

k1,k2,and k10-k12.

Contains k4 and k13, the so called esophageal

type cytokeratins

Page 25: Ultrastructure of gingiva

SULICULAR EPITHELIUM

Also expresses k19 and does not normally contail

merkels cells

Lower degree of enzyme activity than in than in

the outer epithelium especially enzymes related

to keratinization.

Sulcular epithelium has the potential to keratinize

if;

It is reflected and exposed to oral cavity

Bacterial flora of the sulcus is totally eliminated.

Page 26: Ultrastructure of gingiva

JUNCTIONAL EPITHELIUM

Consists of collar like band of stratified squamous

nonkeratinizing epithelium

It is 3-4 layers thick in early life, but the number

increases with age to 10-20 layers

Cells can be grouped into two strata; basal and

suprabasal

Length of JE ranges from 0.25-1.35mm

Formed by confluence of oral epithelium and the

reduced enamel epithelium during tooth eruption

completely restored after pocket instrumentation

or surgery and forms around implants.

Page 27: Ultrastructure of gingiva

JUNCTIONAL EPITHELIUM

Lysosomes-like bodies are present, but the

absence of keratinosomes and acid phosphatase

corelate with low degree of differentiation.

PMN luekocytes routinely found in JE

Expresses k19 which is absent from keratinized

epithelia.

Page 28: Ultrastructure of gingiva

GINGIVAL CONNECTIVE TISSUE

(LAMINA PROPRIA)

Consists of 2 layers;

Papillary layer beneath the epithelium. Consists

of papillary projections between epithelial rete

pegs

Reticular layer, which is in contact with

periosteum of alveolar bone.

COMPONENTS

1. Cellular component

2. Extracellular componet composed of fibers and

ground substance

Page 29: Ultrastructure of gingiva

GROUND SUBSTANCE Fills the space between fibers and cells

Is amorphous

Has a high content of water

Composed of proteaoglycans mainly hyaluronicacid and chondroitin sulfate; and glycoproteinsmainly fibronectin.

Glycoproteins account for the faint PAS positive rxn of ground substance.

Fibronrctin binds fibroblasts to the fibers and other components

Laminin in basal laminae serves to attach epithelial cells to basal laminae

Page 30: Ultrastructure of gingiva

CONNECTIVE TISSUE FIBERS Include ;

Collagen fibers

Reticular fibers

elastic fibers

Collagen type I forms the bulk of lamina propriaand provides tensile strength to gingival tissue

Collagen type IV branches between type I bundles and is continuous with fibers of basement membranes and blood vessels

Elastic fiber system is composed of oxytalan, elaunin, and elastin fibers distributed among collagen fibers.

Page 31: Ultrastructure of gingiva

GINGIVAL FIBERS

Connective tissue of marginal gingiva is densely

collageneous, containing a prominent system of

collagen fiber bundles called gingival fibers

They contain type I collagen

They inclode;

1. Gingival dental

2. Circular

3. Transseptal

Page 32: Ultrastructure of gingiva

FUNCTIONS OF GINGIVAL

FIBERS

To brace marginal gingiva firmly against the tooth

To provide rigidity necessary to withstand forces

of mastication without being deflected away from

the tooth surface

To unite free marginal gingiva with cementum of

the root and the adjacent attached gingiva.

Page 33: Ultrastructure of gingiva

CELLULAR ELEMENTS OF

CONNECTIVE TISSUE OF GINGIVA Fibroblast cells

Most common cells

Synthesize collagen, elastic fibers, glycoproteins, and glycoamineglycans.

Also regulate collagen degradation

Mast cells are numerous in connective tissue of oral mucosa and gingiva.

Fixed macrophages and histiocytes which are derived from blood monocytes

Adipose cells and eosinophils present in lamina propria

Lymphocytes and neutrophils present in small amounts in clinically normal gingiva.

Page 34: Ultrastructure of gingiva

BLOOD SUPPLY TO THE

GINGIVA

Supraperiosteal arterioles

Vessels of periodontal ligament

Arterioles

NERVE STRUCTURES IN CONNECTIVE TISSUE

Meissner- type tactile corpuscles

Krause type end bulbs which are temperature

receptors

Encapsulated spindles

Page 35: Ultrastructure of gingiva

Correlation of clinical and

microscopic featuresCOLOUR OF GINGIVA

Coral pink produced by vascular supply, thickness and degree of keratinization of epithelium, and presence of pigment-containing cells

Colour varies among persons and appears to be correlated with cutaneous pigmentations.

PHYSIOLOGIC PIGMENTATION (MELANIN)

A non haemoglobin-derived brown pigment responsible for normal pigmentation of the skin and oral cavity.

Absent or severely diminished in albinos.

Prominent in black indviduals

Appears in the gingiva as early as 3hrs after birth.

Page 36: Ultrastructure of gingiva

SIZE OF GINGIVA

Corresponds with the sum of the bulk of cellular

and intercellular elements and their vascular

supply

Alteration in size is a feature of gingival disease

CONTOUR / SHAPE OF GINGIVA

Varies and depends on;

1. the shape of the teeth and their alignment in

the arch

2. the location and size ofv the area of proximal

contact

3. The dimensions of the facial and lingual gingival

embrassures

Page 37: Ultrastructure of gingiva

SHAPE OF GINGIVA

Marginal gingiva envelopes teeth and follows

scalloped outline on the facial and lingual

surfaces

On teeth with pronounced M-D convexity (e.g.

maxillary canines) , or teeth in labioversion, the

contour is accentuated and the gingiva is located

farther apically

On teeth in lingoversion, the gingiva is horizontal

and thickened

Page 38: Ultrastructure of gingiva

CONSISTENCY

Gingiva is firm and resilient except the the free

margin

Tightly bound to the underlying bone

Collageneous nature of lamina propria and its

continuity with the mucoperiosteum of alvealor

bone determines the firmnes of attached gingiva

Gingival fibers contribute to the firmness of

gingival margin

Page 39: Ultrastructure of gingiva

SURFACE TEXTURE Similar to orange peel (stippled)

Stippling is best viewed by drying the gingiva

Attached gingiva is stippled, marginal gingiva is not

Pattern and extent of stippling varies among individuals, and different areas in the same mouth

Less prominent on lingual surfaces than facial surfaces and may be absent in some people.

Varies with age. It is absent in infancy, appears in some children at about 5yrs, increases until adulthood and begin to disappear in old age.

Stippling is produced by alternate rounded protuberances and depressions in the gingival surface.

Page 40: Ultrastructure of gingiva

THE END

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