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GINGIVA Contents 01. Introduction

02. Development.

03. Normal clinical features.

04. Normal microscopic features.

05. Gingival collagen fibres.

06. Cuticular structure on tooth.

07. Blood supply, lymphatics and nerves.

08. Correlation of normal and clinical microscopic features.

09. Properties, function and defense mechanism.

10. Age changes in gingiva.

11. Clinical considerations.

1


INTRODUCTION: Periodontium is the functional unit of tissue supporting the tooth. The tooth and periodontium together are called the dentoperiodontal unit. The tissues of the periodontium include the gingiva, the junctional epithelium, the periodontal ligament, the cementum

and

alveolar

process.

They

are

biologically

interdependent. Definition: According

to

Schroeder:

The

gingival or

the

marginal

periodontium is a combination of epithelial and connective tissue, and can be defined as that portion of the oral mucous membrane which in the complete post eruptive dentition of a healthy young individual, surrounds and is attached to the teeth and alveolar process. It covers the alveolar crest, the interdental bony septa, and the coronal portion of the alveolar processes coronally and externally, and extends to the mucogingival junction. According to Carranza: The gingival is the part of the oral mucosa that covers the alveolar process of the jaws and surrounds the necks of the teeth. Development: The gingival tissues develop as a site-specific portion of the oral mucous membrane prior to the eruption of deciduous teeth. Unlike the 3 other tissues of the periodontium (i.e.) root cementum, alveolar bone proper and the periodontal ligament, the gingiva does not derive from the messenchymal dental follicle proper. It is a derivative of the stomodeal ectoderm and mesoderm. 2


The gingival or alveolar ridge 1st appears about 8-9 weeks after ovulation as a result of the formation of the labial and gingival furrow. About 12-14 weeks after ovulation a shallow gingival furrow is formed via an epithelial invagination. The development of the gingival furrow, particularly in the maxillary jaw is associated with the formation of gum pads later in fetal life. About 15 weeks after ovulation epithelial differentiation commences when there is the 1 st appearance of keratohyaline granules in the superficial cell layers. The connective tissue component of the gingiva derives from the perifollicular mesencyme and develops between the tooth germ and epithelium lining the stomodeum at the gingival ridge. Normal clinical features: The oral mucosa consists of 3 zones; the gingiva and the covering of the hard palate ďƒ  termed masticatory mucosa (tends to be bound to bone and does not stretch) (bears forces generated when food is chewed) The gingiva is divided anatomically into Marginal

Attached

Interdental

Marginal Gingiva 1) The marginal or unattached gingiva is the terminal edge or border of the gingiva surrounding the teeth like a collar.

3


2) In about 50% of cases, it is demarcated from the adjacent attached gingiva by a shallow linear depression – The free gingival groove. 3) The marginal gingiva is usually 1mm wide and it forms the soft tissue wall of the gingival sulcus. 4) It can be separated from the surface with a periodontal probe. Gingival sulcus: The gingival sulcus is the shallow crevice or space around the tooth bounded by the surface of tooth one side and the epithelium linking the free margin of the gingival on the other. The shape may vary from an extremely narrow and ill-defined slit to a well-defined shallow groove or rather deep fissure or rather a furrow. It is V shaped and barely permits the entrance of a periodontal probe. The clinical determination of the depth of the gingival sulcus is an important diagnostic parameter under absolute normal conditions the depth is 0 or about 0. In clinically healthy gingiva, a sulcus of some depth can be found histologically. The depth is 1.8 mm with variations from 0 – 6 mm. The probing depth of a clinically normal gingival sulcus in humans is 2 to 3 mm. Development of gingival sulcus: After the enamel formation is complete and before the tooth begins its eruptive movement, the crown of the tooth is covered by a double layer of cells (ameloblasts and reminants of dental organ) – reduced enamel epithelium. 4


Between the REE and the overlying oral epithelial is the connective tissue that supports the REE and the oral epithelial (REE  OL and IL – outer layer flattened cells – remnants of dental organ and inner layer - Ameloblasts). When the tooth eruption begins, this connective tissue breaks down. In response to these degenerative changes, the cells of OL of REE and basal cells of oral epithelium proliferate and migrate into the degenerating connective tissue and eventually fuse to form a mass of epithelial cells (epithelial cuff) over the erupting tooth (epithelial plug). From this epithelial cuff together with the remaining REE the epithelial component of the dentogingival function is established in relation to a degraded connective tissue. The cells of the cuff epithelium proliferates and migrates and becomes separated by widened intercellular spaces. It is through these spaces that antigens from the oral cavity pass as soon as the tip of cusp emerges, initiating an acute inflammatory response in the already altered connective tissue supporting the epithelium. The clinical manifestation of this inflammation response is called ‘Teething’. Gingival fluid (Sulcular fluid): The gingival sulcus contains a fluid that seeps into it from the gingival connective tissue through the thin sulcular epithelial Functions of GCF 1) Cleanses materials from the sulcus. 2) Contains plasma proteins that may improve adhesion of the epithelium to the tooth. 3) It also possesses antimicrobial properties. 4) It exerts antibody activity in defense of the gingiva. 5


Attached gingival: The attached gingiva is continuous with the marginal gingiva. It is firm resilient and tightly bound to the underlying periosteum of alveolar bone. The facial aspect of the attached gingiva extends to a relatively loose and movable alveolar mucosa from with it is demarcated by the mucogingival junction. The width of the attached gingiva is the distance between the mucogingival junction and the projections on the external surface of the bottom of the gingival sulcus on the periodontal pocket. The width of the attached gingiva on the facial aspect is greatest in the incisors – 3.5 to 4.5 in the maxilla and 3.3 to 3.9mm in the mandible and least in the posterior segments with the least width in the first premolar area 1.9.mm in the maxilla and 1.8mm in the mandible. The mucogingival junction remains stationary throughout adult life, therefore changes in the width of the attached gingiva are due to modification in the position of its coronal end. The width of the attached gingiva increases with age, in supraerupted teeth during orthodontic treatment. There are 3 mucogingival lines – Facial maxillary; Facial mandibular; Lingual mandibular. Lingual maxillary is not seen as there is no lingual mandibular alveolar mucosa on the palate and palatal tissue is firmly attached to bone. On the lingual aspect of the mandible, the attached gingiva terminates at the junction with the lingual alveolar mucosa with is continuous with the mucous membrane lining the floor of the mouth.

6


The palatal surface of the attached gingiva in the maxilla blends imperceptibly with the equally firm, resilient palatal mucosa. Reduced or absent attached gingiva may be due to – Base of the pocket is close to the mucogingival line. -

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

-

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

tension test and consists of retracting the cheeks and lips laterally with fingers and checking if such tension pulls the marginal gingiva from the teeth. Reduced width of attached gingiva can be corrected by mucogingival surgery. Interdental gingival: The interdental gingiva occupies the gingival embrasure, which is the interproximal space beneath the area of tooth contact. The interdental papilla is of two types; 1. Pyramidal 2. Col Pyramidal

Col

There is one papilla with its lip Presents

a

depression

that

immediately beneath the contact connects a facial and lingual point.

papilla

and

shape

of

confirms the

to

the

interproximal

contact.

7


The shape of the gingiva in a given interdental space depends on the contact point between 2 adjoining teeth and the presence or absence of some degree of recession. Like the vestibular gingival tissue the interdental gingiva may be divided into

Free

Attached portion

In young individuals the free interdental gingiva is located coronal to the level of the cemento-enamel junction (i.e.) within the boundaries of the junctional epithelia and attached – apical to this level. Its base is at the crest of the interdental septum. The facial and lingual surfaces are tapered towards the interproximal contact area, and the mesial and distal surfaces are slightly concave. If a diastema is present the gingiva is firmly bound over the interdental bone and forms a smooth rounded surface without interdental papilla. Normal microscopic features: The gingiva consists of a central core of connective tissue and is covered by stratified squamous epithelium. Gingival epithelium: Although the gingival epithelium constitutes a continuous lining of stratified squamous epithelium, 3 different areas can be defined from the morphologic and functional point of view 8


1) Oral or outer epithelium 2) Sulcular epithelium 3) Junctional epithelium The principle cell type of the gingival epithelium is the Keratinocyte. Other cells found in the epithelium are the clear cells or nonkeratinocytes, which include the Langerhans cells, the merkel’s cells and the melanocytes. The main function of the gingival epithelium is to ďƒ  protect the deep structures while allowing a selective interchange which the oral

environment.

This

is

achieved

by

proliferation

and

differentiation of keratinocyte. Proliferation of keratinocyte takes place by mitosis in the basal layer and less frequently of cells remain as proliferative compartment while a large number begin to migrate to the surface. Differentiation involves the process of keratinisation, which consists of a sequlae of biochemical and morphologic events that occurs in the cell as it migrates from the basal layer. The main morphologic change is a progressive flattening of the cell, which an increase prevalence of tonofilaments and intercellular junction coupled to the production of keratohyaline granules and the disappearance of the nucleus. A complete keratinisation process leads to the production of an orthokeratinised superficial horny layer (similar to that of skin) with no nuclei in the stratum corneum and a well defined strature granulosum. Only some layers of the outer epithelium are orthokeratinised; the other areas are covered by para or nonkeratinised epithelium. 9


In para-keratinised epithelium the stratum corneum retains the pyknotic nuclei and the keratohyaline granules are dispersed, not giving rise to the stratum granulosum. The

non

keratinised

epithelium

has

neither

stratum

granulosum nor stratum corneum and superficial cells have viable nuclei. Ortho-keratinised

Para-keratinsed

a.Complete

Partial /

keratinisation

incomplete

b. No nuclei in stratum

Pyknotic nuclei in

corneum

stratum corneum

Non keratinised No Keratinisation. Viable nuclei present in all superficial cells.

No stratum c. Well defined stratum

granulosum

No corneum /

granulosum

keratohyaline

granulosum.

granules d. Eg, outer gingival

Eg most areas of

epithelium

gingival epithelium

Eg. Sulcular and junctional epithelium

The keratinising oral epithelium has 4 cell layers 1) Stratum basale 2) Stratum spinosum 3) Stratum granulosum 4) Stratum corneum The basal layer in made up of cells that synthesis DNA and undergo mitosis, thus providing new cells. Some mitotic figures are seen in stratum spinosum therefore the basal cells and parabasal spinous cells are referred to a stratum germinativum.

10


Basal cell are of 2 types: 1. Serrated and heavily packed with tonofilaments (adaptation for attachment) 2. Non- serrated slow cycling stem cells. The serrated basal cells are a single layer of cuboid or high cuboid cells that have protoplasmic processes. Specialized cells called hemidesmosomes with abut on the basal lamina are found on the basal surface. They attach the epithelium to connective tissue. The basal lamina is made up of a clear zone, the lamina lucida just below epithelium cells and a dark zone, The lamina dense beyond the lamina lucida and adjacent to connective tissue. Below lamina densa is a fibrillar zone that is not of epithelial origin. The lateral borders of adjacent basal cells are closely apposed and connected by desmosomes. In the spinousum strata the spinous cells are irregular polyhedral and larger than basal cells. The cells are joined by inter cellular bridges which are desmosomes and tonofibrils are bundles of tonofilaments. Of the 4 layers the spinous layer is the most active in protein synthesis. Stratum granulosum contains flatter and wider cells. These cells are larger than the spinous cells. The layer is so named because of hasophilic keratohyalin granules that it contains. The nuclei shows signs of degeneration and pyknosis. Odland body or membrane forms in the upper spinous and granular cell layers. 11


Stratum corneum: a)

Is made up of keratinised squamae, which are larger and flatten than the granular cells.

b)

All nuclei and ribosomes and mitochondria have disappeared.

c)

Keratohyaline granules have disappeared.

Others cells or non-keratinocytes present are: Level in epithelium

Cell Type

Melanocytes

Basal and Spinous

Function Synthesis of melanin pigment (Melanosome) Regulatory cell.

Langerhans

Supra Basal

Macrophage. (Birbeck’s granules)

Merkel’s Cell

Basal

Tactile perception.

Both epithelial proliferation and maturation are needed for continuous cells renewal to maintain structural integrity. The control over these 2 processes is mediated by substances produced by maturing epithelial cells – Chalones which act by negative feedback mechanism. Structural and

Metabolic

characteristic

of

the

gingival

epithelium. The oral or outer epithelium covers the crest and outer surface of the marginal gingival and the surface of the attached gingival. It is keratinised or parakeratinised or a combination of these surfaces. The prevalent surface however is parakeratinised 12


At the gingival margin the epithelium forms ridges only running parallel to this margin. The basal complex underlying the proximal epithelial surface consists of a distinct lamina lucida and lamina densa bearing, Anchoring fibrils – They are short curving filament fascicles about 20-40nm thick which traverse the basal lamina and fan out into the underlying connective tissue forming loops around adjacent collagen fibrils and thereby anchoring the basal lamina to the connective tissue. The basal complex formerly called the basement membrane includes the basal lamina, the anchoring fibrils and a band like zone of reticulin fibres which is highly reactive which PAS, Sudan black and silver stains with a total thickness of about 1mm. The basement membrane of oral gingival epithelium contains type II and V collagen and non-collagenous glycoproteins, laminin and heparan sulphate, proteoglycan and fibronectin. Keratins – K1, K2 and K10, K11 which are specific to epidermal differentiation

are

expressed

which

high

intensity

in

orthokeratinised areas and with less intensity in parakeratinised areas. Parakeratinised areas express K-19 which is usually absent from orthokeratinised normal epithelial. Sulcular epithelium: The epithelia lining the gingival sulcus are the junctional epithelium forming the sulcus bottom and the oral sulcal epithelum forming the lateral sulcus wall, which extends coronally into the oral gingival epithelium at the gingival margin. 13


The sulcular epithelium is thin, non-keratinised stratified squamous epithelium without rete-pegs. Although it does not keratinise it has a strong structural resemblance to the stratified keratinising oral epithelium and may exhibit a tendency towards keratinization without producing an ortho or para keratinised surface. The sulcular epithelium has the potential to keratinise if 1) It is reflected and exposed to the oral cavity. 2) Or the bacterial flora of the sulcus is totally eliminated. The superficial cells may be rather thin flat, dark basophilic and electron dense. The oral sulcal epithelium cells reveal a concentration of cytoplasmic

filaments,

an

accumulation

of

glycogen

storage

granules,keratohyalinegranules and lipid droplets. It contains K 4 and K13 the oesophageal type cytokeratins. The sulcular epithelium is extremely important because 1) It may act as a semipermeable membrane through which injurious bacterial products pass into the gingiva and 2) Through which tissue fluid from the gingiva seeps into the sulcus. Junctional epithelium: Development: The junctional epithelium is derived from the reduced enamel epithelium (prior to tooth eruption the enamel surface in man is covered by a layer of reduced ameloblasts and epithelial cells external to them). During the stages of amelogenesis following completion of the secretory phase, both reduced ameloblasts and the external cells 14


assume the typical features of resorptive cells. Concomitant with the change from secretory to resorptive function, an attachment apparatus

(i.e.)

an

basal

lamina

and

typically

structured

hemidesmosomes appear between the enamel surface and the reduced ameloblasts. The sum total of internal basal lamina with the

hemidesmosomes

has

been

termed

primary

epithelial

attachment. The junctional epithelium is derived from the reduced enamel epithelium through a transformation process which progresses concomitant

with

the

eruption

of

the

tooth.

During

this

transformation the primary epithelial attachment which has been maintained by ameloblasts, becomes the secondary epithelial attachments which is maintained by new cells now termed the junctional epithelium. The junctional epithelium is attached to the tooth surface epithelium by means of the internal basal lamina and to the gingival connective tissue by an external basal lamina. The junctional epithelium attaches to the afibrillar cementum when it is present on the crown and to the root cementum in a similar manner. The junctional epithelium consists of a collar like band of stratified squamous non keratinising epithelium. It is 3-4 layer thick in early life, but the number of layers increase with age to 10 or even 20. These cells can be grouped into 2 strata.

Basal

Suprabasal.

15


The length of the junctional epithelium ranges from 0.25 to 1.35mm. Cell layers not juxtaposed to the tooth exhibit numerous free ribosomes and prominent membrane bound structures such as golgi complexes, lysosome like bodies and cytoplasmic vacuoles. Junctional epithelia exhibit K-19 keratin polypeptides and stratification specific cytokeratins K-5 to K-14. Neutral polysaccharides are present in the zone of epithelial attachment. The cells of the junctional epithelium are involved in the production of laminin and play a key role in the adhesion mechanism. The attachment of the junctional epithelium to the tooth is reinforced by the gingival fibres which brace the marginal gingiva against the tooth surface. For this reason the junction epithelium and gingival fibres are considered to be a functional unit – referred to as dentogingival unit. Differences between Junctional epithlium The size of the cells relative to the tissue volume is larger The intercellular space relative to the tissue volume is layer The number of desmosomes is more

Oral epithelium Is smaller

Smaller

Less

Epithelium retepegs and connective tissue papilla are lacking at the junctional

Present

epithelium contiss interface Non-keratinised

Keratinised / parakeratinised

16


Dentogingival junction: The interface between the gingival tissue and the supraalveolar, cervical region of fully erupted teeth, deciduous or permanent teeth is termed the dentogingival junction. At both the vestibular and the interdental aspects this junction consists of an 1) epithelial and a 2) connective tissue boundary and both types of interface provide biological attachment of the soft to the hard tissues. The coronal part of the dentogingival juction is mediated through

the

junctional

epithelium

generating

the

epithelial

attachment. The apical part consists of connective tissue fibres inserting into the acellular extrensic fibre cementum. These two types of attachment meet at the cementoenamel junction ideally. The junctional epithelial covers the first 2mm of the cervical enamel, while the connective tissue attachment is to the root surface. Gingival connective tissue: The connective tissue of gingiva is called lamina propria. It consists of a 2 layers 1) Papillary layer – Subjacent to the epithelial that consists of papillary projections between the epithelial retepegs. 2) Reticular layer – which is contiguous with the periosteum of alveolar bone. The papillary body comprises a variable dense array of connective tissue papillae ranging from 50-200/mm 2. the epithelum is thrown to form ridges into which the papilla are interlocked. This interlocking 1) increases the area of contact between the epithelium and lamina propria 2) facilitates exchange of materials to the epithelium and blood vessels.

17


Papillae: The papillae vary in distribution and shape from Tall conical; to short and plump. Branching papillae occur infrequently Height of papilla – 100 to 400µm. Width of papilla – 40 to 90 µm. Ridges were also found to be of the same dimensions. Lamina propria consists of 1) cells, 2) Fibrous proteins and 3) ground substance to the 4) inter cellular matrix as well as 5) vascular elements and nerves. The total lamina propria volume comprise about 8% cells, 57% fibrous proteins and 35% residual tissue with consists of blood, lymphatic vessels and nerves. Cells of lamina propria include 1) Fibroblasts 2) Mast cells 3) Small number of mono and poly morphonuclear leucocytes acting on host defense. Most numerous is fibroblast Fibroblasts: They are spindle shaped cells and range in size between 100800mm3 and are scattered and oriented between bundles of collagen fibrils and around blood vessels. Fibroblasts produce connective tissue substance including proteoglycans, collagen and elastic and maintain the integrity of lamina propria (the gingival fibroblasts synthesis collagen type I, III and V and collagenase and collagenase inhibitors in latent proenzyme form). 18


The elastic fibre system is composed of oxytalin, elaunin and elastin fibres distributed among collagen fibrils. They occur in both papillary body and the bulk of connective tissue. Predominantly in the blood vessel walls but also intermingled with dense collagen fibre bundles. The inter or exracellular matrix of the gingival lamina propria comprises various fibrous proteins such as collagen, reticular and very little elastin and ground substance collagen is predominant structural constituent, which accounts for about 30% of the tissue dry weight. Add for about 60% of the total tissue protein. Type I accounts for 91% forms bulk and provides. Type III for 8% tensile strength. Type V less than 1%. Type I – found preferentially in regions with dense bundles of collagen fibrils. Type III collagen is related to predominantly loose pattern of connective tissue organization found along basement membranes underneath the oral gingival epithelium and around blood vessels. The gingival lamina propria contain argyrophilic reticulin fibers (Type IV). The reticulin forms a network which includes 3 groups of fibrils. 1) Interfibriller reticulin esheating collagen fibre bundles. 2) Subepithelial reticulin – ramifying between which is part of papilla. 3) Reticulin in the walls of blood vessels. The ground substance of the gingival lamina propria contains non-collagenous glycoproteins proteoglycans and water. They also contain acid mucopolysaccharides ďƒ  chondroitin sulphates, hyaluronic and sialic acids.

19


Gingival collagen fibres: The gingival fibers consists of type I collagen. The gingival fibres have 3 functions. 1) To brace the marginal gingiva firmly against the tooth. 2) To provide rigidity necessary to withstand the forces of mastication without being deflected away from the tooth surface. 3) To units the free marginal gingiva with the cementum of the root and the adjacent attached gingiva. Most of the collagen fibrils are arranged into bundles of fibres with preferential orientation. The sum total constitute the supraalveolar fibres apparatus. They are described as 11 types. 1) Dentogingival 2) Dentopereosteal. 3) Alveologingival 4) Semicircular 5) Circular 6) Transgingival 7) Intergingival 8) Interpapillary 9) Periosteal – gingival 10) Intecircular 11) Transplit fiber groups. I. Dentogingival fibres: Take 3 major routes 1.

Radiate coronally to the gingival margin ďƒ  in part passing directly beneath the junctional. Epithelium and terminating in the papillary body at the oral sulcus and oral gingival epithelial of the gingival margin.

2.

Follows a rather horizontal course. 20


Extending across gingiva at right angles to the tooth and terminating in the papillary body underneath the oral gingival epithelium. 3.

Runs parallel to the dentoperiosteal fibres.

II. Dentoperiosteal fibres: Arise from the supra alveolar root cementum at the same level as the transeptal fibres but occur only in the vestibular gingiva. (They pass over the alveolar bone crest and terminate apically in the periosteum of the alveolar process). III.

Alveologingival fibres inserting in the alveolar bone crest and the interdental septum, radiate coronally into the gingival lamina propria.

IV.

The semicirucular and circular fibres encircle the tooth entirely or partially within the marginal and interdental gingiva coronal to the transeptal fibres.

V.

The

transgingival and intergingival fibres reinforce the

circular and semicircular fibres. VI.

The interpapillary fibers form a discrete group which passes in the buccolingual direction through the coronal portion of interdental gingiva connecting the vestibular with oral gingival papilla.

VII.

The periosteogingival fibers arise from the periosteum of the alveolar process, vestibularly and fan out into the attached portions of the gingiva overlapping the alveolar bone crest.

VIII. The intercircular fibers connect the circular and possibly the semicircular fibres. IX. Transeptal fibers: Line in the mesiodistal plane apical to the circular and semicircular fibres but coronal to the crest of interdental bony septum. Collectively they are termed as interdental ligament. (The elongated and polarized fibroblasts of the transeptal fibres

have

been

shown

to

contain

variable

amounts

of 21


microfilament bundles, possible actin, oriented parallel to the cell’s long axis. These bundles are termed- stress fibres. In addition oxytalin fibres are contained in this apparatus. Cuticular structure on the tooth: The term cuticle is used to describe a thin acellular structure with a homogenous matrix, sometimes enclosed within clearly demarcated linear borders. Classification (Listgarten) 1)

Acquired coatings of exogenous origin – saliva, calculus, surface stains.

2)

coatings of developmental origin – are those normally formed as part of tooth development. a.

Reduced enamel epithelium

b.

Coronal cementum

c.

Dental cuticle

Blood supply, lymphatics and nerves: 3 sources of blood supply to gingiva a)

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

b)

Vessels of periodontal ligament. which extend into the gingiva and anastomose with capillaries in the sulcus area.

c)

Arterioles that emerge from the crest of the interdental septa. The lymphatic drainage brings in the lymphatics of the

connective tissue papilla and drain into the regional lymphnodes mostly the submaxillary group. Lymphatics just beneath the junctional epithelium extend into the periodontal ligament and accompany the blood vessels. 22


Nerve supply region

Innervations Anterior posterior and middle

Upper gingiva

superior alveolar branches of maxillary nerve, palatal nerves. Inferior alveolar branch of

Lower gingiva buccal and lingual

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

The following nerve structures are present in connective tissue. 1)

Meshwork of terminal argyrophilic fibres.

2)

Meissner’s type tactile copuscles.

3)

Krause type end bulbs – temperature

4)

Encapsulated spindles receptors.

Correlation of normal and clinical microscope features: Appearance in healthy gingiva

Microscopic features

Changes in disease / clinical appearance

Causes for change

a. Color Uniformly pale pink / coral pink melanin pigmentation occurs as a diffuse, deep purplish discolouration or as irregularly shaped brown and light brown patches

a) Vascular supply. b) Thickness and degree of keratinisation of epithelium presence of pigment containing alls.

Chronic – bluish pink/bluish red

-

Vessels engorged

-

Blood flow sluggish

-

Venous return impact

b. Size- Not include 23


Corresponds to the sum total of bulk of acellular and inter cellular elements and their vascular supply.

Enlarged

Edematous inflammation fluid cellular exudates haemorrhage

Governed by the proximal tooth surface and the location and shape of gingiva embrasure

Rolled / rounded

Inflammation changes edema or fibrous.

The collagenous nature of lamina propria and its contiguity with the periosteum of the alveolar bone.

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

Odematous fluid between cells in the connection

c. Shape Marginal gigniva knife edge, follows a curved line around the tooth d. Consistency

Firm and resilient

Clinically the surface of attached gingiva resembles that of an orange

peel.

It

is

characterised

by

numerous,

irregularly

distributed, finely grained or coarse round to oval or even split like depressions – stipples. They are about 0.6 to 1.4mm in diameter or length and 1-5 mm or 3-5mm in depth. More on facial aspect of maxillary anterior and less on anterior mandibular.

24


Surface texture: The gingiva presents Alteration of rounded Absent a

textured

with that

surface protubeculance

stippling of

an

peel.

in

infancy

and and in old age.

like depression in gingiva

orange surface. The papillary

(attached layer

gingiva). Marginal gingiva is not stippled

tissue the

of

connective

projects elevation

elevation

and

into both dep

layers are covered by stratified

sq.

epithelium. Stippling is a form of adaptive reinforcement or specialization for function. Loss of stippling is a common sign of gingival disease. Position: The position of gingiva refers to the level at which the gingival margin is attached to the tooth surface. Exposure of the tooth by apical migration of gingiva is called gingiva recession or atrophy. According to concept of continuous eruption. It consists of Active eruption – movement of teeth in the direction of occlusal plane. Passive eruption – exposure of teeth by apial migration of gingiva. Passive eruption is divided into 4 stages.

25


1)

Stage 1 – The teeth reach the line of occlusion. The junctional epithelium and base of the gingival sulcus are on the epithelium.

2)

Stage 2 – The junction epithelium proliferates so that part is on the cementum and part is on the enamel. The base of the sulcus in still on the enamel.

3)

Stage 3 – The entire junctional epithelial in on the cementum and the base of the sulcus is on the CEJ.

4)

Stage 4 – The junctional epithelium proliferates farther on the cementum. The base of the junction epithelial is on the cementum, a portion of which is exposed. It is accompanied by degeneration of gingival and PL fibres and their detachment from the tooth.

Properties, functions and defense mechanisms: As the gingiva represents both the most peripheral part of the periodontium and a portion of oral mucous membrane its properties and functions are 2 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 keratinisation help in the adaptation to these physical requirement. b)

It is a mucostable tissue 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

26


a)

It ensures dental arch linkage and controls the positioning of teeth in the horizontal plane by means of its supraalveolar fibre apparatus. These fibres along which those of PDL secure teeth against rotational forces and generate forces resulting in mesial drift.

b)

It maintains gingival and periodontal health by means of various defense mechanical operating within the gingival tissue. This peripheral defense action of gingiva has 2 arms.

1)

The humoral arm which represents the generation of gingival fluid.

2)

The cellular arm which represents the continuous emigration of neutrophilic granulocytes via the junctional epithelium.

Defense mechanism: The gingival tissue is constantly subjected to mechanical and bacterial aggression. Resistance to these actions is provided by the -

Sulcular fluid.

-

Saliva

-

Epithelial surface

-

Permeability of junctional and sulcular epithelial.

-

Leukocytes The

gingival

sulcular

fluid

contains

proteins,

specific

antibodies and antigens, enzymes and cellular elements. The gingival fluid is an inflammatory exudate. The amount of fluid is greater when there is inflammation resent. It is increased by mastication of coarse food, tooth brushing gingival massage, ovulation, hormonal contraceptives, smoking, etc. Drugs like tetracycline and metronidazole are excreted through the gingival fluid. 27


Leukocytes have been found to have phagocytic and killing capacity. Therefore they constitute a major protective mechanism against extension of plaque into the gingival sulcus.

28


Saliva secretions are protective in nature. It exerts a major influence on plaque by; 1)

Mechanically cleansing the exposed oral surface.

2)

Buffering the acids produced by bacteria.

3)

Controlling bacterial activity.

Renewal of gingival epithelium: The oral epithelium undergoes continuous renewal. Its thickness is maintained by a balance between new cell formation in the basal and spinous layers and the shedding of old cells at the surfaces. The mitotic activity exhibits a 24 hour periodicity with highest and lowest rates occurring in the morning and evening respectively. The mitotic rate is higher in non-keratinized area and is increased in gingivitis Age changes in the gingival: Following changes in gingiva have been identified with aging 1)

Diminished keratinization.

2)

Reduced or unchanged amount of stippling.

3)

Increased width of attached gingiva.

4)

Decreased connective tissue cellularity.

5)

Greater amount of intercellular substance.

6)

Reduced oxygen consumption.

7)

An increase or no change in the mitotic index of gingival epithelium.

Clinical considerations: When we a preparing dental treatment like cavity and crown cutting proper protection of gingiva is necessary. If there is any damage of the gingival tissue it sometimes will lead to periodontal disease. While preparing crown just below free gingiva care must be taken not to damage attached gingival tissue.

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Proper

contact

should

be

maintained

to prevent

food

lodgement so as to avoid gingival damage. When using matrix bands, wedges and separators care must be taken to prevent damage. If there is any hypertrophy it should be removed before restorative treatment. REFERENCES:  Textbook of Oral Histology and Embryology - Orbans.  Clinical Periodontology – Glickman.

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Gingiva / dental implant courses by Indian dental academy