ultrastructure of gingiva
ULTRASTRUCTURE OF GINGIVA
Part of the oral mucosa that covers alveolar
process of the jaws and surrounds the neck of
It is anatomically divided into three parts;
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
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
Width of attached gingiva is clinical parameter
Width of attached gingiva is greatest in incisor
region and least in first premolar area.
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.
SHAPE OF INTERDENTAL
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
Gingiva can be divided into two main parts
Stratified squamous epithelium
Connective tissue core
Gingival epithelium is functionally and
morphologically classified into three parts.
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.
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
Production of keratohyaline granules
Dissapearance of the nucleus
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
These areas can progress to maturity or
dedifferentiate under physiologic or pathologic
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
Reveals that keratocytes are interconnected by
structures on the cell periphery called
Desmosomes have a typical structure consisting
of two dense attachement plaques into which
Tonofilaments radiate in brush like fashion from
attachement plaques into cytoplasm of cells.
Less frequently observed forms of epithelial cell
Membranes of adjoining cells are believed to be
These structures allow ions and small molecules
to pass from one cell to another.
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
Enzymes of pentose shunt such as G6Pase
increase their activity towards the surface. This
pathway produces RNA used in synthesis of
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.
melanocytes: for production of melanin
Langerhans cells: have phagocytic activity
Merkels cells: tactile perceptors
Connects epithelium to underlying connective
Consists of lamina lucida and lamina densa.
Hemidesmosomes of the basal lamina tourch the
lamina lucida, which is mainly composed of
Lamina densa is composed of type IV collagen.
STRUCTURAL AND METABOLIC X-
TICS OF DIFFERENT AREAS OF
ORAL/ OUTER EPITHELIUM
Covers the crest and outer surface of the
marginal gingiva, and the surface of attached
It is keratinised, pparakeratinized, or in
Prevalent surface is however parakeratinized
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
Parakeratinized areas express k19, which is
usually absent from orthokerakinized areas.
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
Contains k4 and k13, the so called esophageal
Also expresses k19 and does not normally contail
Lower degree of enzyme activity than in than in
the outer epithelium especially enzymes related
Sulcular epithelium has the potential to keratinize
It is reflected and exposed to oral cavity
Bacterial flora of the sulcus is totally eliminated.
Consists of collar like band of stratified squamous
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
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.
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
GINGIVAL CONNECTIVE TISSUE
Consists of 2 layers;
Papillary layer beneath the epithelium. Consists
of papillary projections between epithelial rete
Reticular layer, which is in contact with
periosteum of alveolar bone.
1. Cellular component
2. Extracellular componet composed of fibers and
GROUND SUBSTANCE Fills the space between fibers and cells
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
CONNECTIVE TISSUE FIBERS Include ;
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.
Connective tissue of marginal gingiva is densely
collageneous, containing a prominent system of
collagen fiber bundles called gingival fibers
They contain type I collagen
1. Gingival dental
FUNCTIONS OF GINGIVAL
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.
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.
BLOOD SUPPLY TO THE
Vessels of periodontal ligament
NERVE STRUCTURES IN CONNECTIVE TISSUE
Meissner- type tactile corpuscles
Krause type end bulbs which are temperature
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.
SIZE OF GINGIVA
Corresponds with the sum of the bulk of cellular
and intercellular elements and their vascular
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
2. the location and size ofv the area of proximal
3. The dimensions of the facial and lingual gingival
SHAPE OF GINGIVA
Marginal gingiva envelopes teeth and follows
scalloped outline on the facial and lingual
On teeth with pronounced M-D convexity (e.g.
maxillary canines) , or teeth in labioversion, the
contour is accentuated and the gingiva is located
On teeth in lingoversion, the gingiva is horizontal
Gingiva is firm and resilient except the the free
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
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.