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GINGIVA The periodontium (peri-around, dontium-tooth, greek) consists of investing and supporting tissues. The investing tissue of the periodontium is known as the GINGIVA. It is the most peripheral portion of periodontium at large. According to the Dorland Medical Dictionary, the word gingiva means the ‘gum of the mouth’. It is that part of the oral mucosa overlying the crown of unerupted teeth and encircling the necks of these that have erupted, serving as the supporting structure for the subadjacent tissues. DEFINITIONS 1.

CARANZA Is the part of oral mucosa that covers the alveolar processes of jaw

and surrounds the neck of teeth. 2.

SCHROEDER It is a combination of epithelium and connective tissue and is

defined as that portion of oral mucous membrane, which in complete posteruptive dentition of a healthy young individual, surrounds and is attached to the teeth and the alveolar processes. 3.

GRANT Is the part of oral mucous membrane attached to the teeth and the

alveolar processes. 1


4.

LINDHE Is that part of masticatory mucosa covering the alveolar processes

and the cervical portions of teeth. FUNCTIONS As the gingiva represents both the masticatory mucosa as well as the most peripheral part of the periodontium, its functions are two fold. I] As part of the oral mucosa It protects the supporting tissues from the oral environment. a) As part of oral mucosa, it is subjected to friction and pressure in the masticatory process. Its densely collagenous lamina propria, peripheral sensory innervation and keratinization help in the adaptation to these physical requirements. b) It is a mucostable tissues because of its firmness, scalloped contour, close adaptation and attachment to the underlying structures. c) Gingival tissues fulfill the functions of sensitivity and resistance. II] As part of the periodontium The gingiva exhibits functional properties: a) It ensures dental arch linkage and controls the positioning of teeth in the horizontal plane by means of its supra-alveolar fibre apparatus. These fibres along with those of PDL secure teeth against rotational forces and generate forces resulting in mesial drift. 2


b) It maintains gingival and periodontal health by means of various defense mechanism operating within the gingival tissues. This peripheral defense action of gingiva has two arms: 1. The humoral arm which represents the generation of gingival fluid. 2. The cellular arm which represents the continuous irrigation of neutriphilic granulocytes via the junctional epithelium. Both these arms keep a 24 hour watch on the periodontal health. Development Unlike, the other tissues of the periodontium which are derived from the ectomesenchymal dental follicle, the gingiva is a derivative of mesoderm. According to Schroeder, the shape, topographical distribution and width of the gingiva are functions of the presence and position of erupted teeth. He also says that, there are reasons to assume that the gingival tissues exist and develop as a site specific portion of the oral mucous membrane prior to the eruption of deciduous teeth. Thereafter, the gingiva although increasing size serves both deciduous and permanent teeth.

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Normal Clinical Features Gingiva is divided into: Oral part

Vestibular part

Anatomically, it has been divided into: -

MARGINAL gingiva

-

ATTACHED ginigiva Pyramidal

-

INTERDENTAL gingiva Col

A] Marginal gingiva / Free gingiva / Margio Gingivalis Definition It is the terminal edge or border of the gingiva surrounding the teeth like a collar.

Figure 4


It is demarcated from the adjacent attached gingiva by a shallow linear depression – the free gingival groove. This is about 1mm wide and forms the soft tissue wall of the gingival sulcus. According to Schroeder, the term ‘free gingiva’ is a clinical designation and relates to the clinical property of the gingival rim. B] Attached Gingiva It is continuous with the marginal gingiva. It is firm, resilient, and tightly bound to the underlying tissues of the alveolar bone. On the facial aspect, the attached gingiva extends to the relatively loose and movable alveolar mucosa from which it is demarcated by the mucogingival junction (3 M G Lines) Facial maxillary

Facial mandibular

Lingual mandibular

# Lingual maxillary is not seen as there is not alveolar mucosa on the palate and the palatal tissue is firmly attached to the bone. Width of the attached gingiva Is defined as the distance between the mucogingival junction and the projection on the external surface of the bottom of the gingival sulcus / periodontal pocket. It is generally greatest in the incisor region (3.5 – 4.5mm in maxilla and 3.3 – 3.9mm in mandible) and less in the posterior region with least in the 1st premolar area (1.9mm in maxilla and 1.8mm in mandible).

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The width of the attached gingiva increases with age and supraerupted teeth. Reduced / Absent Attached gingiva may be due to: -

base of the pocket is close to the mucogingival line.

-

frenal / muscle attachments that encroach on pockets and pull them away from the tooth surface.

-

denudation of root surfaces. Adequacy of the attached gingiva can be determined by the

TENSION TEST which consists of retracting the cheeks and lips laterally with fingers and checking if such tension polls the marginal gingiva from the teeth. Reduced width of attached gingiva can be corrected with mucogingival surgeries. C] Interdental Gingiva

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It occupies the gingival embrasure, which is the interproximal space beneath the area of tooth contact Types: Pyramidal

Col

 Where there is one papilla with  Which represents as a depression its tip immediately beneath the that connects a fascial and a lingual contact point.

papilla and conforms to the shape of interproximal contact.

1) Various anatomic variations of the interdental col in the normal gingiva and after gingival recession GINGIVAL SULCUS -

Is the shallow space / crevice around the tooth bounded by the surface of the tooth on one side and epithelium lining the free margin of the gingiva on the other.

-

It is V-shaped and rarely permits the entrance of a periodontal probe. Under normal circumstances, the depth is 0 In histologic sections – 1.8mm. The probing depth is 2-3mm

GINGIVAL FLUID / SULCULAR FLUID (GCF)  The gingiva sulcus contains a fluid that seeps into it from the gingival connective tissue through the thin sulcular epithelium.

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Function of GCF: -

cleanses material from the sulcus.

-

Contains plasma proteins that may improve adhesion of the epithelium to the tooth.

-

It also possesses antimicrobial properties.

-

It exerts antibody activity in defense of the gingiva.

NORMAL MICROSCOPIC FEATURES The gingiva consists of a central core of c.t. (lamina propria) covered by stratified squamous epithelium. Gingival Epithelium From the morphologic and function points of view 3 different types are seen. Oral / Outer Sulcular Junctional Functions To protect the deep structures while allowing a selective interchange with the oral environment (achieved by proliferation and differentiation of keratinocytes). Later The principle cell is the keratinocyte. -

Proliferation takes place by mitosis.

-

Differentiation involves the process of keratinization. 8


The main morphologic change is the progressive flattening of the cell. 3 types of keratinization can be seen: Histologically, a keratinized epithelium shows a number of distinct layer. I] St Corneum It is the surface of very flat eosinophilic cells. II] St Granulosum Larger flattened cells that contain kerato-hyaline granules. The upper most layer of stratified spi contains numerous granules called keratinosomes / odland bodies. III] St Spinosum / Prickle cell Layer

Larger elliptical / spheroidal cells. When prepared for histologic sections, these cells shrink away from one another remaining in contact only at patients known as intercellular bridges / desmosomes. IV] St Basale Proliferative layer. 3 types Ortho Keratinocyte -

Complete keratinocyte

-

No nuclei in st corneum

Para Keratinocyte -

-

Partial incomplete keratinocyte Pyknotic 9

Non-keratinocyte / -

No keratinocyte

-

No corneum / granulosum

nuclei


-

Well defined St. granulosum e.g. layers of outer gingival epithelium

in st corneum -

Keratinohyaline granules

-

No st granulosum e.g. most areas of gingival epithelium

Keratinization The prot syn during maturation process – keratolinin and involved in form an envelope below the cell membrane (chemically resistant structure). As the cells reach the corneum keratin or disappear and give rise to a protein – fillagirin which forms the matrix of the most differentiated epithelial cells – CORNEOLYTE. Cell type

Level in epithelium

Functions

1. Melanocyte

Basal

2. Langerhans cells

Predominantly suprabasal

Synthesis pigment

3. Merkels cells

Basal

of

melanin

Regulatory cell Macrophage (contain granules)

Birbeck’s

Tactile perception Both epithelial proliferation and maturation are needed for continuous cell renewal to maintain structural integrity. The control over these two processes is mediated by substance produced by maturing epithelial cells – CHALONES which acts by –ve feedback mechanism.

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STRUCTURE EPITHELIUM

AND

CHARACTERISTICS

OF

GINGIVAL

I] Oral / outer epithelium It covers the crest / outer surface of the marginal gingiva and the surface of the attached gingiva. It is keratinized / parakeratinized or present various combinations of these conditions. The prevalent surface is however parakeratinized. -

In orthokeratinized areas  Keratins K1, K2 and K-10, K-12 which are specific for epidermal differentiation are expressed with high intensity.

-

K6 and K16  characteristic of highly proliferative epithelium K1, K2, K-10, K-12 – expressed with low intensity in parakeratinized area. These also express K-19 which are absent from Ortho keratinized

area. II] Sulcular epithelium -

Lines the gingival sulcus.

-

It is a thin, non-keratinized squamous epithelium without retepegs, which extends from the coronal limit of junctional epithelium to the crest of the gingival margin.

-

It shows cells and with hydropic degeneration.

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-

It contains keratins K4 and K13, also expresses K-19. It lacks stratum granulosum and corneum, cytokeratins K1 and K2 and K10K12 and also lacks Merkels cells.

It has the potential to keratinize, if: a) It is reflected and exposed to the oral cavity. b) The bacterial flora of the sulcus is totally eliminated. These findings suggest that the local irritation of the sulcus (due to its contact with tooth) prevents sulcular keratinization.

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Functions of sulcular epithelium It acts as a semi-permeable membrane three which injurious bacterial pass into the gingiva and three which tissue fluid from the gingiva seeps into the sulcus. III] Junctional epithelium -

Consists of a collar-like band of stratified squamous nonkeratinizing epithelium.

a) It is 3-4 layers thick in early life, but it increases with age to 10-20. b) The length ranges from 0-25 – 1.35 mm. c) It is widest in its coronal portion (15-20 cell layers) but becomes thinner towards the CEJ. d) It expresses K-19 and the stratification specific cytokeratins K5 and K14. Histology of junctional epithelium Is a continuous self-renewal structure and is continuously renewed through cell division occurring in the basal layer. The cells migrate to the base of the gingival sulcus, from where they are shed. Cells are arranged in 2 strata Basal

Suprabasal

Both are flattened with their long axis 11 to the tooth surfaces

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Functions -

Unlike the epithelial connective tissue interface, the lamina densa of the internal basal layer (facing the enamel) has no anchoring fibrils attached to it, which means that the junctional epithelium is physically attached to the tooth via the hemidesmosomes (Schroerder).

-

The attachment of the junctional epithelium to the tooth is further reinforced by the gingival fibres which brace the marginal gingiva against the tooth surface for this reason. Junctional epithelium and gingival fibres are a function unit

FIBRES The connective tissue fibres are: Collagen Reticulum Oxytalan Elastic Collagen – 65% of C.T. volume Tropocollagen (smallest unit of a collagen are aggregated longitudinally to form molecule) after synthesis, it is secreted out from the fibroblasts into extracellular space. Protofibril laterally aggregates to in II form collagen fibrils with an overlapping of tropocollagen mole by about 25% of their lengths. -

These are bundles of collagen fibrils, aligned in such a way that fibres exibit a cross-binding.

Collagen Type I 14


-

Forms the bulk of lamina propria and provides tensile strength.

-

Gingival collagen fibres – consists of Type I collagen.

Functions: -

To brace the marginal gingiva firmly against the tooth.

-

To provide rigidity necessary to without and the forces of mastication without being deflected from the tooth surfaces.

-

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

Reticulum -

Are present at the epithelial connective tissue and the endothelium c.t. interface.

Oxytalan -

are present in all c.t. structure of the periodontium and are composed of long thin fibrils. They regulate vascular flow. In the PDL, these fibres run 11 to the root surfaces in a vertical direction and bend to attach to cervical 3rd of cementum.

-

Are present in all C.T. of gingiva and periodontal only in association with the blood vessels.

GINGIVAL FIBRES Carranza (1996) -

Gingiovodental.

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-

Circular.

-

Transeptal.

-

Semicircular

-

Transgingival

MATRIX -

Constitutes the environment for the cell. It is produced by fibroblasts and is composed of protein polysaccharides and macromolecules. Proteoglycans

Glycoproteins

BLOOD SUPPLY 3 sources of blood supply to gingiva (Carranza 1996). a)

Supra-periosteal arterioles Along the fascial and lingual surface of the alveolar bone, from

which capillaries extend along the sulcular epithelial and between the retepegs of the external gingival surface. b)

2 vessels of the PDL – which extend into the gingiva anastomose with capillaries in the sulcus area.

c)

Arterioles which emerge from crest of the interdental septa. Nerve supply region

- Upper gingiva

Innervation Anterior, post and middle supraalveolar branches of maxillary 16


nerve, palatal nerves. Lower gingiva buccal and lingual

Infection alveolar branch of mandibular nerve, buccal branch of mandibular nerve, sublingual branch of lingual nerve.

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Lymphatic drainage -

Brings in the lymphatics of the C.T. papillae. It progresses to the regional lymph nodes.

CO-RELATION OF NORMAL CLINICAL FEATURES AND MICROSCOPIC FEATURES Appearance in health 1. Colour

Changes in disease / clinical appearance

Uniformly pale a) Chronic pink / coral pink bluish pink Variations in bluish red

Causes for changes

– /

pigmentation related to race

Vessels engorged

-

Blood flow sluggish and

-

Venous return impaired

-

Edematous inflammatory fluid, cellular exudates hemorrhage

2. Size

Not enlarged fits Enlarged snugly around the tooth

3. Shape

a) Marginal Rolled / rounded gingiva : Knife edge, follows a curved line around the tooth

Inflammation changes, edema or fibrosis

4. Consistency

Firm

Edematous fluid between cells in the connective tissue

Soft, spongy, red colour, dents readily when pressed with a probe, smooth and shiny surface

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5. Surface texture

Represents that of an orange pell and is known as stippling. The attached gingiva is stippled – not the marginal. It varies with age, is absent in infancy increase till adulthood and disappears in old age. It is produced by alternate protruberances & depressions in the gingival surfaces.

-

Exposure of the tooth by the apical migration of gingiva is called gingival recession / atrophy Physiologic /Pathologic occurs.

References: 1. Clinical Periodontology by Carranza, Newman and Takei. 2. Periodontics by Grant, Stern and Listgarten.

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Gingiva

SEMINAR BY Dr. N.Upendra Natha Reddy Postgraduate Student

2004-2007 20


Contents 1. Definition 2. Function 3. Development 4. Normal Clinical Features 5. Gingival Fluid / Sulcular Fluid (Gcf) 6. Normal Microscopic Features 7. Structure

and

Characteristics

Of

Gingival

Epithelium 8. Gingival Fibers 9.

Blood supply* Nerve supply * Lymphatic drainage

10.

Normal clinical features and microscopic

features 11.

References

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Gingiva (2)/ dental implant courses by Indian dental academy