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GINGIVA
CONTENTS:
1) INTRODUCTION
2) DEFINITIONS
3) DEVELOPMENT OF GINGIVA
4) NORMAL CLINICAL FEATURES
MARGINAL GINGIVA.
A...
1) INTRODUCTION
The Periodontium (peri-around, dontium-tooth, Greek) consists of
investing and supporting tissues. The inv...
GENCO:- Gingiva is that part of oral mucous membrane that covers the alveolar
processes of the cervical portions of the te...
(A) MARGINAL GINGIVA / FREE GINGIVA / MARGO GINGIVALIS /
UNATTACHED GINGIVA.
DEFINITION: 1) It is the terminal edge or bor...
FUNCTIONS OF GCF:
1) Cleanses material from the sulcus.
2) It contains plasma proteins that may improve adhesion of the ep...
Lingual maxillary is not seen as there is no alveolar mucosa on the palate and
palatal tissue is firmly attached to the bo...
another sex differentiation in females the majority of the nuclei contain a large
chromatin particle adjacent to the nucle...
The principal cell type of Gingival epithelium as well as have other stratified
squamous epithelia is the keratinocyte. Ot...
structure of desmosome:
Desmosomes considered as 2 hemidesmosomes facing one another. Desmosome
consists of 2 adjoining he...
Lamina Lucida: Clear zone about 45µm wide, adjacent to the epithelial cell
membrane called the lamina Lucida, to which hem...
B. A large population of Amplifying cells whose function is to increase
the number of cells available for subsequent matur...
The main morphologic changes seen are.
1) Progressive flattening of the cell.
2) Increasing prevalence of tonofilaments an...
is made up of a clear zone. The lamina Lucida just below epithelial cells and a
dark zone. The lamina dense beyond the lam...
Three types of keratinization are seen.
Ortho keratinization Para- keratinization Non keratinization
A) Complete A) partia...
bundles; membrane membrane coating
coating granules appear granules appear in upper
In upper part of this layer part of la...
granular layer, both the number of tonofilaments in the cytoplasm and the number
of desmosomes increase. In contrast, the ...
2. The organelles disappear as they reach the surface. This disappearance is
brought about by Keratinosomes  Odland bodies...
migrate to the basal aspect of epithelium of the 2nd
week of gestation. There they
divide and maintain themselves as self ...
the presence of small rod (or) flask shaped granules sometimes called the
“Birbeck” granule (or) also called tennis racket...
Lymphocytes:
Lymphocytes found in gingival epithelium are associated with an inflammatory
process. They may be found anywh...
The epithelial cells covering the transplanted alveolar mucosa, which is
non keratinized, had migrated to the newly formed...
These findings suggest that the local irritation of the sulcus (because of its contact
with tooth) prevents sulcular kerat...
. Differences between
Junctional epithelium Oral epithelium
The size of the cells relative to the
tissue volume is larger
...
hemidesmosomes (Schroereder and Listgarten). The junctional epithelium attaches
to afibrillar cementum when it is present ...
1) Cells – 5% (mainly fibroblast)
2) Fibers- 60% (mainly collagen)
3) Vessels, nerves and matrix – 35%
Cells:- 1)Fibroblas...
and each chain consisting of about 1000 amino acids (1/3rd
glycine, 20% proline
and Hydroxy proline). After the synthesis ...
1) Dento gingival, 1) Transgingival,
2) Dento periosteal, 2) Inter gingival,
3) Alveolo gingival, 3) Inter papillary,
4) C...
alveolar crest propria alveolar bone.
2. Dento gingival Cementum Lamina
propria
Support to the gingiva by
attaching it to ...
B.Interpapillary fibers. Extending facio- lingual
direction in the inter-
dental gingiva.
Vestibular and
oral gingival
pap...
parallel to the root surface in a vertical direction and bend to attach to cervical 3rd
of cementum. They are thought to r...
Blood supply
Maxilllary gingiva sub terminal branches
Anterior. Anterior superior alveolar artery
Lingual Major palatine a...
Buccal and lingual:branch of mandibular nerve sub-lingual branch of lingual
nerve.
Receptors are seen as free endings with...
Defense mechanism:-
1) The humoral arm which represents the production of gingival fluid.
2) The cellular arm which repres...
2) Stage 2: The junctional epithelium proliferates so that part is on the
cementum and part is on the enamel. The base of ...
such as 1) Reduced enamel epithelium
2) The coronal cementum and
3) The dental cuticle.
1) Reduced enamel epithelium: Afte...
II As part of the periodontium:-
A) The gingiva exhibits functional properties. It ensures dental arch linkage
and control...
anterior mandibular. Stippling is a form of adaptive reinforcement on
specialization for function loss of stippling is a c...
Appearance in healthy gingiva Microscopic features Changes in
disease/
clinical
appearance
Cause for change
A) color
Unifo...
D). consistency
Firm and resilient
E).Surface texture
The gingiva presents a
textured surface with stippling
like that of ...
Gingiva / rotary endodontic courses by indian dental academy
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Gingiva / rotary endodontic courses by indian dental academy

  1. 1. GINGIVA CONTENTS: 1) INTRODUCTION 2) DEFINITIONS 3) DEVELOPMENT OF GINGIVA 4) NORMAL CLINICAL FEATURES MARGINAL GINGIVA. ATTACHED GINGIVA INTERDENTAL GINGIVA. 5) NORMAL MICROSCOPIC FEATURES A. GINGIVA EPITHELIUM ORAL EPITHELIUM SULCULAR EPITHELIUM JUNCTIONAL EPITHELIUM. B. GINGIVAL CONNECTIVE TISSUE GINGIVAL COLLAGEN FIBERS CONNECTIVE TISSUE CELLUR COMPARTMENT BLOOD SUPPLY, LYMPHATICS AND NERVES. 6) FUNCTIONS OF GINGIVA 7) AGE CHANGES IN GINGIVA 8) CORRELATION OF NORMAL AND CLINICAL MICROSCOPIC FEATURES 9) CLINICAL CONSIDERATIONS 10) SUMMARY AND CONCLUSION 11) REFERENCES.
  2. 2. 1) INTRODUCTION 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. Therefore some times it is referred to as the marginal periodontium. 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 periodontal ligament, and the cementum and alveolar process. They are biologically interdependent. According to the ‘Dorland medical Dictionary’ the word Gingiva means the ‘gums of the mouth’. It is that part of the oral mucosa overlying the crowns of unerrupted teeth and encircling the necks of those that have erupted, serving as the supporting structure for sub adjacent tissues. The oral mucosa is classified into three different types. 1) Masticatory mucosa: Gingival and the covering of hard palate. 2) Specialized mucosa: Dorsum surface of tongue. 3) Lining mucosa: The remainder of the oral mucous membrane. 2) DEFINITIONS:- CARRANZA:- Gingiva is the part of oral mucosa that covers the alveolar processes of jaws and surrounds the neck of teeth SCHROEDER:- It is a combination of epithelium and connective tissue and is defined as that portion of oral mucous membrane, which in complete post eruptive dentition of a healthy young individual surrounds and is attached to the teeth and the alveolar processes. GRANT:- Gingiva is the part of oral mucous membrane attached to the teeth and the alveolar processes.
  3. 3. GENCO:- Gingiva is that part of oral mucous membrane that covers the alveolar processes of the cervical portions of the teeth. LINDHE:- Gingiva is that part of masticatory mucosa covering the alveolar processes of the cervical portions of teeth. 3) DEVELOPMENT OF GINGIVA The gingival develops as a coalescence of oral and enamel organ epithelia, as the tooth emerges into the oral cavity, the reduced enamel organ epithelium covering the surface of the tooth fuses with the oral epithelium, with further tooth eruption. The reduced enamel epithelium separates from the primary cuticle on the surface of the enamel. The resulting cuff of epithelium and connective tissue surrounding the neck of the tooth becomes the gingiva. The reduced enamel organ epithelium continues its apical separation along the enamel surface until the tooth reaches occlusion. At that point, the gingiva covers only the cervical portion of the crown. Thereafter, the epithelium attachment is limited to a zone at the Cemento Enamel junction. Unlike three other tissues of the periodontium i.e. cementum, alveolar bone and periodontal ligament, the gingiva does not derive from the mesenchymal dental follicle proper. It is a derivative of the stomodeal ectoderm and mesoderm. 4) NORMAL CLINICAL FEATURES. Anatomically, Gingiva has been divides into. (A) MARGINAL GINGIVA. (B) ATTACHED GINGIVA (C) INTERDENTAL GINGIVA.
  4. 4. (A) MARGINAL GINGIVA / FREE GINGIVA / MARGO GINGIVALIS / UNATTACHED GINGIVA. DEFINITION: 1) It is the terminal edge or border of the gingiva surrounding the teeth like a collar. 2) In about 50% of cases, it is demarcated from the adjacent attached gingiva by a shallow linear depression- The free gingiva 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. Defined by four Boundaries: 1. Coronally: by gingival margin 2. Apically: by free gingival groove 3. Inner margin: by gingival sulcus 4. Outer surface by vestibular or oral cavity. In absence of this free gingival groove, the apical boundary would correspond to a line opposite the bottom of the gingival sulcus, which is usually about 1.0 to 1.5mm apical to the free gingival margin. The free gingival groove Histological appearance as v-shaped notch at a heavy epithelial ridge. The free gingival groove develops at the level of or somewhat apical to, the bottom of the gingival sulcus. GINGIVAL SULCUS: DEFINITION: Is the shallow crevice or space around the tooth bounded by the surface of the tooth on one side and the epithelial lining the free margin of the gingiva on the other. It is V-shaped and barely permits the entrance of a periodontal probe. Under absolutely normal / ideal conditions, the depth of gingival sulcus is 0 are about 0. In clinically health gingiva in humans, Histologic depth 1.8mm with variations from 0-6mm. Probing depth 2-3mm. GINGIVAL FLUID: The gingival sulcus contains a fluid that seeps into it from the gingival connective tissue through the thin sulcular epithelium.
  5. 5. FUNCTIONS OF GCF: 1) Cleanses material from the sulcus. 2) It contains plasma proteins that may improve adhesion of the epithelium to the tooth. 3) It possesses antimicrobial properties. 4) It exerts antibody activity in defense of the gingiva. ATTACHED GINGIVA: The attached gingiva is continuous with the marginal gingiva. It is firm, resilient. and tightly bound to the underlying periosteum of the alveolar bone. The attached gingiva lies between the free gingival mucosa and alveolar mucosa. It is separated from the former by the free gingival groove and from the latter by the mucogingival junction. WIDTH OF ATTACHED GINGIVA: It is defined as the distance between the mucogingival Junction and the projection on the external surface of the bottom of the gingival sulcus or the periodontal pocket. It should not be confused with the width of keratinized gingiva, because the keratinized gingiva includes marginal gingiva. The width of the attached gingiva is determined by subtracting the depth of the sulcus / pocket from the distance of the crest of margin to the mucogingival Junction. It is also determined by. 1) Schillers potassium Iodide solution. 2) Pushing the alveolar mucosa coronally with a blunt instrument. The width of attached gingiva on the facial aspect differs in different areas of the mouth. It greatest in the Incisor region, 3.5 to 4.5mm in the maxilla, 3.3 to 3.9mm in the mandible Less in the posterior segments. Least width in the 1st premolar area 1.9mm in maxilla and 1.8 mm in the mandible. There are 3 micro gingival lines. 1) Facial Maxillary 2) Facial Mandibular 3) Lingual mandibular
  6. 6. Lingual maxillary is not seen as there is no alveolar mucosa on the palate and palatal tissue is firmly attached to the bone. Lingual mandible, the attached gingiva terminates at the junctional with lingual alveolar mucosa which is continuous with the mucosa membrane lining the floor of the mouth. Width of attached gingiva increased with 1) Age 2) Supraerupted teeth. Width of attached gingiva decreased with 1) Base of the pocket is apical / close to muco gingival line. 2) High Frenum attachment. 3) Gingival recession. In Type II, III, IV. Importance of attached gingiva. 1) Act as a mechanical barrier. 2) Resistance to functional stress. 3) Act as buffer between movable marginal gingiva and immovable alveolar mucosa. Adequacy of attached gingiva can be determined by Tension test. Consists of retracting the checks and lips laterally with fingers and checking if such tension pulls the marginal gingiva from the teeth. This reduced width of attached gingiva can be corrected by mucogingival surgery. The attached gingiva is characterized by a surface that appears stippled portion at the epithelium appears to be elevated, and between the elevations there are shallow depressions, the net result of which is stippling. The depression corresponds to the center of heavier epithelial ridges. These are due to functional adaptations to mechanical impacts. The disadvantage of stippling is an indication of edema i.e. progressing gingivitis. In younger females stippling is more prominent than males, due to finely textured connective tissue However with increasing age the collagenous fiber bundles become coarser in both sexes. Males tend to have more heavily stippled gingival than females. Oral epithelium shows
  7. 7. another sex differentiation in females the majority of the nuclei contain a large chromatin particle adjacent to the nuclear membrane. INTERDENTAL PAPILLA:- Is that part of the gingiva that fills the space between two adjacent teeth. When viewed from the oral or vestibular aspect, the surface of the Inter dental papilla is triangular, in a three dimensional view the Inter dental papilla of the posterior teeth is tent shaped, where as it is pyramidal between the anterior teeth. When the Inter dental papilla is tent shaped the oral and vestibular corners are high, where as central part is like a valley. The central concave area fits below the contact point, and this depressed part of the Inter dental papilla is called col. Col refers to a pass between adjacent peaks of a mountain. Col is the shelter reservoir for entrapped food. When gingiva is inflamed and hyperemic, the Col is exaggerated. The Col usually exhibits signs of inflammation, because it is difficult to keep the Inter proximal area clean because of plaque and calculus form there, with the age Col flattens. Col is covered by thin non keratinized epithelium which is more vulnerable to periodontal disease. If diastema is present the gingiva is firmly bound over the Inter dental bone and forms a smooth rounded surface with out inter dental papilla. Gingival epithelium Functions: The main function is to protect the deep structures while allowing a selective interchange with the oral environment (achieved by proliferation and differentiation of keratinocytes). Cells of the epithelium:
  8. 8. The principal cell type of Gingival epithelium as well as have other stratified squamous epithelia is the keratinocyte. Other cells are the clear cells on Non keratinocytes Keratinocytes: content of epithelial cell is keratin, hence keratinocytes synthesize keratin and constitute about 90% of the gingival epithelium. Fine structure of the epithelial cell: Tonofilaments : They are fibrous proteins synthesized by the ribosome’s and are seen as long filament with a diameter of approximately 8µm. They belong to class of intermediate filaments and form cytoskeleton of keratin proteins when they become aggregated to form bundles of filaments, they are called as Tonofibrills. Junctions between the cells of the epithelium The epithelium functions as a barrier due to the close contact (or) cohesiveness of the epithelial cells. This cohesion between cells is provided by viscous intercellular material consisting of protein carbohydrate complexes provided by the epithelial cells. In addition to these, there are specialized in addition to thee, there are specialized structures which provide the connection between the cells / keratinocyte these are. I) Desmosmes: Consists of 2 dense attachment plaques one from each cell separated by interval of 30µm wide that contains three dense lamellae. Bundles of tonofilaments insert into the attachment plaques and these loop in and out of the attachment plaque without crossing into the adjacent cells. In a desmosome, the membranes come so close together, their glycoprotein rich surface coats (or) the plaque touch forming an intermediate electron dense line in the extra cellular compartment. If epithelial cells shrink during histologic processing, desmosomes usually remain intact and so appear as inter cellular bridges.
  9. 9. structure of desmosome: Desmosomes considered as 2 hemidesmosomes facing one another. Desmosome consists of 2 adjoining hemidesmosomes, separated by a zone containing electron dense granulated material. In addition, desmosome consists of. 1) Outer leaf let(OL) of cell membranes of two adjoining cells 2) Thick, inner leaf let (IL) of the cell membranes. 3) The attachment plaque (AP) which represent granular and fibrillar material in cytoplasm. Desmoplakin : is a protein, forms the attachment plaque of desmosome but not of hemidesmosome. Hemidesmosome: consists of a single attachment plaque present between a cell and a non cellular surface (only one cell membrane is present). Its glyco protein rich coat is compressed to form a dense line midway in the space between the cell and non cellular surface. Eg. Adhesion between the epithelium and connective tissue is provided by Hemidemosomes present on the basal membranes of the cells of the basal layer. Tonofilaments are also inserted into attachment plaque of hemidesmosomes. Functions of the Desmosomes, Hemidesmosomes and Tonofilments. These structures together represent a mechanical linkage that distribute and dissipates localized forces that are applied on the epithelial surface over a wide area II Tight junctions: (Zona occludens) Rarely seen. Adjacent membranes are so tightly apposed that there is no intercellular space and appear to be fused. III Gap junctions: is a region, where adjacent cell membranes run closely together, separated by only a small gap. These Junctions may allow electrical / chemical communication between the cells. Basal lamina:- 300 to 400 A0 Thick (1) Lamina Lucida. (2) Lamina Densa.
  10. 10. Lamina Lucida: Clear zone about 45µm wide, adjacent to the epithelial cell membrane called the lamina Lucida, to which hemidesmosomes are attached. Contents:1) Glycoproteins i.e. laminin. 2) Bullous pemphigoid antigen. Lamina Densa: Fine granular (or) filamentous material 50µm, thick called the lamina Densa. Separated from the epithelial cell membrane by the lamina Lucida. -Anchoring fibrils: (Zona Reticularis) from lamina Densa small loops of finely banded fibrils are inserted called as anchoring fibrils are composed of VII collagen. -Collagen fibrils: Run through these loops of anchoring fibrils and are thus interlocked with the lamina Densa to form a flexible attachment. Type I and II. -Type IV Collagen is present in L. Densa. Bio chemically lamina Densa arranged in a “chicken wire” configuration. It is now believed that all the basal lamina except the anchoring fibrils is synthesized by the epithelium. Keratinization The oral epithelium maintains its structural integrity by a system of continuous cell renewal and involves the two processes of proliferation and differentiation. Thus, the cells of the epithelium can be considered to be of two functional populations. 1) A Progenitor population:- Whose function is to provide new cells. 2) A Maturating population:-Whose cells are undergoing a continuous process of differentiation and maturation to form a protective surface layer. Epithelial proliferation: The progenitor cells are situated mainly in the basal layer. Recent studies have shown that the progenitor compartment is not homogeneous, but consists of two functionally distinct subpopulation of cells. A. A small population of stem cells whose function is to produce basal cells and thus retain the proliferative potential of the tissue.
  11. 11. B. A large population of Amplifying cells whose function is to increase the number of cells available for subsequent maturation. Regardless of the cell type, either stem (or) amplifying cells, cell division is a cyclic activity and is divided into 4 phases. 1) (S) Synthetic phase: During this phase, cells which are preparing to divide initially, double their DNA content. 2) G3 Phase :– Represents a short rest period. 3) (M) Mitotic phase:- (Only histologically distinguishable phase) which is subdivided into stages of - Prophase - Metaphase - Anaphase - Telophase Cells enter these phases of mitosis to produce two daughter cells. After the cell division, each daughter cell makes the decision either to recycle in the progenitor population (or) to enter the maturating compartment. This decision making period is known as 4 Dichophase(D) on an average, one daughter cell enters the maturation compartment and other enter post mitotic pre synthetic period G1. The time necessary to replace all the cells in the epithelium is known as the turnover time of epithelium, Turn over time for gingiva has been estimated to be 41-57 days (rate of cell proliferation). Epithelial Proliferation / differentiation. Daughter cells that have arisen from the cell division in the basal layers, either recycle (or) undergo a process of maturation as they move to the surface maturation / differentiation involves the processes of keratinization, which is defined as a process that consists of a sequence of biochemical and morphologic events that occur in the cell, as it migrates from the basal layer to the surface.
  12. 12. The main morphologic changes seen are. 1) Progressive flattening of the cell. 2) Increasing prevalence of tonofilaments and inter cellular junctions. 3) Production of keratohyalin granules. 4) Disappearance of the nucleus. Functions of keratinization:- Formation of a protective surface layer, the formation of a surface layer of keratin makes the epithelial surface of the masticatory mucosa and regions of specialized mucosa inflexible, tough and resistant to abrasion. Histologically the keratinized epithelium shows a number of distinct layers of strata. THE KERATINIZING ORAL EPITHELIUM HAS FOUR CELL LAYERS. 1) STRATUM BASALE 2) STRATUM SPINOSUM 3) STRATUM GRANULOSUM 4) STRATUM CORNEUM. 1) STRATUM BASALE or proliferate layer. The cells of stratum basale are cuboidal (or) low columnar, in shape with protoplasmic processes located immediately suprajecent to the basement membrane. These cells made up of cells that synthesize DNA and undergo mitosis, thus providing new cells. Sometimes mitotic figures are seen in stratum spinosum there fore basal cells and Para basal spinous cells and called Stratum Germinativum. Basel cells are of two types. 1) Serrated and heavily packed with tonofillaments. (Adaptation for attachment). 2) Non- serrated slow cycling stem cells. Specialized cells called hemidesmosomes, which adapt the basal lamina, are found on basal surface. They attach the epithelium to connective tissue. The basal lamina
  13. 13. is made up of a clear zone. The lamina Lucida just below epithelial cells and a dark zone. The lamina dense beyond the lamina Lucida and adjacent to connective tissue. Below basal lamina is a fibrillar zone that is not of epithelial origin. The lateral borders of adjacent basal cells are closely apposed and connected by desmosomes. 2) STRATUM SPINOSUM or prickle cell layer:- Located above basal cell layer. These cells appear to possess spinous or spiky process, hence the name “spinosum”. The process is due to cell shrinkage during histologic processing. The spinous cells are irregular polyhedral and larger than basal cells. The cells are joined by intercellular bridges which are desmosomes and tonofibrils are bundles of tonofilaments of the four layers spinous layer is the most active in protein synthesis. The two layers stratum basale and stratum spinosum account for one third to two third of total epithelial thickness. 3) STRATUM GRANULOSUM:- Contains flatter and wider cells. These cells are larger than the spinous cells. This layer is so named because of basophilic keratohyalin granules that it contains, these granules are dense and relatively large 0.5to1um, these are present in cytoplasm. The keratohyalin Granules are believed to function in the process of keratinization. The cell of this layer is of 3-5 cells thick. Odoland body or keratinosome membrane forms in the upper spinous and granular cell layers. 4) STRATUM CORNEUM Also called the cornified layer it consists of flattened eosinophilic cells. The cells of the stratum corneum are flat, devoid of nuclei and full of keratin filament surrounded by a matrix. The junction between the nucleated cells in the stratum granulosum and stratum corneum is quite abrupt. This layer is characterized by almost exclusive presence of tonofibrils in the cytoplasm. The outermost cells of this zone are shed during the process of exfoliation.
  14. 14. Three types of keratinization are seen. Ortho keratinization Para- keratinization Non keratinization A) Complete A) partial / incomplete A) No Keratinization Keratinization Keratinization B) No nuclei in B) Pyknotic nuclei B) Viable nuclei Stratum corneum in stratum corneum. present in all Superficial cells C) Well defined stratum C) No stratum granulosum C) No S. corneum/ granulosum keratohyaline granules granulosum. D) Example:-outer D) Ex: - most areas of D) Ex:-Sulcular & gingival epithelium. gingival epithelium junctional epithelium . The gingiva is 75% parakeratinized. 15% keratinized. 10% Non Keratinized. KERATINIZED EPITHELIUM NONKERATINIZED EPITHELIUM Cell layer major features cell layers major features Basal Basal Cuboidal / columnar cells Cuboidal / columnar of cells containing bundles of containing separate tonofibrils and other tonofilament and other cell cell organelles; organelles. Site of majority of cell site of majority of cell divisions. divisions. Spinous Layer Prickle Cell Larger ovoid cell containing larger ovoid cell containing conspicuous tonofibril dispersed tonofilament
  15. 15. bundles; membrane membrane coating coating granules appear granules appear in upper In upper part of this layer part of layer and filament become numerous. Granular Intermediate Flattened cell containing slightly flattened conspicuous keratohyaline cell containing granules associated with tonofibrils. numerous dispersed membrane coating granules tonofilaments and fuse with cell membrane in glycogen upper part; there is also internal membrane thickening Keratinized Superficial Extremely flattened and slightly flattened cells with dispersed dehydrated cells in which fragmented glycogen; fewer organelles all organelles have been lost; present but nuclei persist to the surface. cells . Keratinization:- The basal cells posses the ability to undergo cell division. Therefore, it is in the basal layer that the epithelium is renewed and so, this layer called Stratum Germinativum. When two daughter cells have been formed by cell division, an adjacent older basal cell (OB) is pushed into the spinous layer and starts as a keratinocyte to transverse the epithelium, it takes approximately one month for a keratinocyte to reach the stratum corneum, from where it is desquamated under normal circumstances, there is complete equilibrium between the cell renewal and desquamation. As the basal cell migrates through the epithelium, it becomes flattened and has its long axis parallel to the tissue surface. The keratinocyte undergo continuous differentiation and specialization. From the basal layer to the
  16. 16. granular layer, both the number of tonofilaments in the cytoplasm and the number of desmosomes increase. In contrast, the number of organelles such as mitochondria, lamellae of rough endoplasmic reticulum and Golgi complexes decrease in the keratinocyte as they reach the surface. In the Stratum Granulosam, electron dense keratohyalin granules and clusters of glycogen containing granules start to occur such granula are believed to be related to the synthesis of keratin. Thus, once the keratinocyte has left the basement membrane, it can no longer divide but maintain a capacity for production of proteins (Tonofilments and keratohyalin granules). In the granular layer, the keratinocyte is deprived of its energy and protein producing apparatus (probably by enzymatic break down) and is abruptly converted into a keratin filled cell, which from the stratum corneum is shed from the tissue surface. Main events occurring in the maturation ( keratinized epithelium). As keratinization progresses, basal cells initially synthesize low molecular weight keratin proteins (such as K19, 40kd) and later express other higher molecular weight proteins, as they migrate to the surface, main component of stratum corneum is keratin 68kd (k1). 1. Other proteins are also synthesized during the maturation process keratolinin and involucrin which form a chemically resistant structure called the envelope located below the cell membrane. Now as the cells of the granular layer reach the Junction of Stratum Corneum (or) keratinized layer, all the organelles including the nuclei and the keratohyaline granules disappear. Keratohyaline granules are irregular in shape, about 9 µm in diameter, and probably synthesized by the ribosome’s. On reaching the corneum layer, these granules disappear and give rise to a protein called fillagrin, which forms the matrix of the corneocytes. Thus, in a fully differentiated state corneocytes are mainly formed by bundles of keratin tonofilaments embedded in an amorphous matrix of fillagrin surrounded by a envelope under the cell membrane (formed by keratolinin and involucrin).
  17. 17. 2. The organelles disappear as they reach the surface. This disappearance is brought about by Keratinosomes Odland bodies. Which are modified lysosomes, located in the uppermost cells of the stratum spinosum. They secrete acid phosphatase, an enzyme involved in the destruction of organelle membrane. 3. Enzymes of the pentose shunt (alternative pathway of glycolysis) increase their activity towards the surface. As a result, there is more RNA formed (due to breakdown) and thus more synthesis of keratinization proteins). As a result of these factors, cells of the keratinized layer are dehydrated, flattened and resistant to mechanical damage and chemical solvents. In 3-D, they have the form of hexagonal discs, called squame. These are lost by desquamation and replaced back by the underlying cells. The degree of gingival keratinization diminishes with age and onset of menopause. Most keratinized areas in decreasing order – palate, gingiva, tongue and cheek Control of epithelial proliferation and maturation 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 maturating epithelial cells called chalones. Chalones act by negative feed back mechanism. The slower the rate of maturation, the lower the local chalone concentration and greater the mitotic activity. Non keratinocytes: 1.Melanocytes. The color of the mucosa is the net result of number of factors. One of which is pigmentation which is endogenous and exogenous. The endogenous pigmentation is most commonly contributed by melanin. Melanin is produced by melanocytes. These are situated in the basal layer of the oral epithelium. Melanocytes are derived embryo logically from the neural crest ectoderm and
  18. 18. migrate to the basal aspect of epithelium of the 2nd week of gestation. There they divide and maintain themselves as self reproducing population of cells. Melanocytes are astral shaped cells and are characterized by presence of long cellular process known as dendritic processes these cytoplasmic extension pass between the adjacent keratinocytes, often passing through several layer of cells. These cells do not contain desmosomes and tonofilaments. However, they do contain an extensive Golgi zone and a well developed rough endoplasmic reticulum. Melanin is synthesized with in melanocytes and stored in oval shaped small structure known as melanosomes.(Melanin synthesis begin in the endoplasmic reticulum]. Tyrosinase Synthesized in ribosome’s passed via Endoplasmic reticulum to Golgi system. In Golgi system it accumulates in vesicles, Vesicle develops to form Helical protein fibrils Called Pre melanosome (Tyrosinase).Oxidizes to form DOPA (3-4-Dihydroxy phenol – L – alanine. Polymerizes into Pigment melanin. Melanosomes are melanin containing granules approx 0.1 to 0.4µm in size. The function of melanocytes is not known. All individual possess same number of melanocytes regardless of color of skin (or) oral mucosa. Difference in pigmentation is primarily the result of the activity of the melanocytes and the enzymatic processes there in and the rate at which the melanosomes are breakdown in keratinocytes. In persons with heavy melanin pigment cells containing melanin may be seen in the connective tissue (probably macrophages have taken up these melanosomes- these cells are referred to as melanophages ). Regardless of the activity of the melanocytes, there are approximately 7-9 melanocytes for every 100 basal cells (or) about 1660 melanocytes / mm2 of outer epithelium surface. Langerhan’s Cell: Like the melanocytes, the langerhan’s cell is a dendritic cell, usually seen in the supra basal layer, often in the Stratum Spinosum. The dendritic processes extend throughout Stratum Spinosum. This cells lack desmosomal attachments to surrounding cells and no tonofilaments. The langerhan’s cell is characterized by
  19. 19. the presence of small rod (or) flask shaped granules sometimes called the “Birbeck” granule (or) also called tennis racket organelles in cytoplasm. These arise from pynocytotic vesicle i.e. from sac like invagination of the plasma membrane. The langerhan’s cell contains well developed golgi bodies, rough endoplasmic reticulum and numerous vacuoles. The nucleus is multiply notched, thus has irregular contour. The langerhan’s cell derived from bone marrow and is equivalent to modified monocytes and migrates to the epithelium. They move in and out of the epithelium. This is an evidence suggesting that they have an immunologic function. These recognize and posses antigenic material that enter the epithelium from the external environment and presents it to helper T- Lymphocytes. It is also likely that langerhans cells can migrate from epithelium to regional lymph nodes. Thus they play a role in immune mediated reaction of oral mucosa. In the oral gingival epithelium there are on an average of 160 langerhan’s cells every Sq.mm of epithelium surface. Function: Langerhan’s cells are antigen presenting cells. They engulf antigens from the external environment, and the intracellular lysosomes split the antigens into peptide components. These fragment’s are then transferred to T-lymphocytes which are important cells in the immune system. Merkel’s Cells: Merkel cells are located in the basal cell layer of the gingival epithelium and appear individually (or) in clusters. These cells appear similar to keratinocytes possessing tonofilaments and desmosomes. These are not dendritic cells. The characteristic feature of Merkel cell is presence of small spherical membrane bound vesicle in the cytoplasm. This spherical mass filled with dark osmiophilic substance / granular. These vesicles are situated adjacent to nerve fiber and these granules may liberate a neuro - transmitter substance across the synapse like Junction between the Merkel cell and nerve fiber and their trigger an impulse. This arrangement resemble with neuro physiologic evidence suggest that Merkel’s cells are sensory and respond to touch and pressure.
  20. 20. Lymphocytes: Lymphocytes found in gingival epithelium are associated with an inflammatory process. They may be found anywhere in the gingival epithelium but most often are in the area of junctional epithelium. Leucocytes: Leucocytes are found in the gingival epithelium. Usually in the sulcular and attached epithelium. These cells move between the epithelial cells and through its surface and become salivary corpuscles. They contribute protein and immunochemical substances to the sulcular fluid. Keratinisation A genetic phenomenon:- It has been suggested that the presence of keratinized epithelium on the masticatory mucosa is a functional adaptation to the mechanical irritation caused by mastication. To prove this assumption wrong, a very interesting research experiment was carried out. In a monkey, the gingival (G) and the alveolar mucosa (AM) were transposed surgically. The gingival which is keratinized was positioned in the area of the alveolar mucosa which is non keratinized and the alveolar mucosa was placed in close contact with the teeth. After 4 months, it was seen that the transplanted gingival had retained its characteristics, morphological features of a masticatory mucosa, that is, it exhibited a distinct surface layer of keratin along with the epithelium connective tissue interface (i.e. rete pigs and connective tissue papillae). This observation showed that the characteristic of the gingiva was genetically determined rather than an adaptation to environmental stimuli. However, a narrow Zone of a new keratinized gingiva (NG) has regenerated between the transplanted alveolar mucosa and the teeth, there by pushing the alveolar mucosa to become interposed between the transplanted and the newly formed gingiva. The connective tissue of the new gingival has regenerated from the connective tissue of the supra alveolar and PDL compartments.
  21. 21. The epithelial cells covering the transplanted alveolar mucosa, which is non keratinized, had migrated to the newly formed gingival connective tissue. However, the epithelium covering the new gingiva was found to be keratinized. This implicated that the newly formed gingival connective tissue possessed the ability to induce differentiation of the epithelium, which was derived from the non keratinized, transplanted alveolar mucosa. Thus, we can see that the specificity of the gingival epithelium is determined by genetical factors inherent in the connective tissue. I. The oral / outer epithelium: Covers the crest and outer surface of the marginal gingiva and the surface of the attached gingiva. It is keratinized / parakeratinized (or) present as various combination of these surfaces. The prevalent surface however is parakeratinized. In orthokeratinized areas Keratins K1, K2, K10, and K12.Which are specific for epidermal differentiation, are expressed with high intensity K6, K16 characteristics of highly proliferate epithelium. In parakeratinized areas Keratins K1, K2, K110, and K12. Which are expressed with low intensity. These areas also express K19, which is usually absent from ortho keratinized area. II. The sulcular epithelium: Lines the gingival sulcus. It is thin, non keratinized, stratified squamous epithelium without rete pegs, which extends from the coronal limit of the junctional epithelium to the crest of the gingival margin. It usually shows numerous cells with hydropic degeneration. It contains keratin K4 , K13 and K19. It lacks stratum granulosum and corneum. cytokeratins K1 K2 K10, and K12. Lacks merkel cells. The sulcular epithelium has the potential to keratinize, if: 1) It is reflected and exposed to the oral cavity, 2) The bacteria flora of the sulcus is totally eliminated.
  22. 22. These findings suggest that the local irritation of the sulcus (because of its contact with tooth) prevents sulcular keratinization. Functions of sulcular epithelium. It may act as a semi permeable membrane through which injurious bacterial products pass into the gingiva and through which tissue fluid from the gingival seeps into the sulcus. III. The junctional epithelium: (j.e) The junctional epithelium consists of a collar- like band of stratified squamous non-keratinizing epithelium that joins gingival connective tissue to the tooth surface. 1. It is 3-4 layers thick in early life, but the number of layers increases with age 10 to 20. 2. The length of the junctional epithelium ranges from 0.25 to 1.35mm 3. It is widest in its coronal portion about 15-20 cell layers but becomes thinner towards the CEJ 4. Cell layers not juxtaposed to the tooth, exhibit numerous free ribosomes’, golgi complexes lysosome like bodies, cytoplasmic vacuoles and PMN’s and leukocytes. 5. The J.E expresses K19 (with is absent for keratinized epithelium) and stratification with specific cytokeratins K5 and K14. Histologic features: Like the oral epithelium, the junctional epithelium is continuous self-renewal structure and is continuously renewed through cell division occurring in the basal layer. The cells migrate to the base of gingival sulcus from where they are shed. Cells are arranged in 2 Strata: Basal and suprabasal. The basal and suprabasal cells are flattened with their long axis parallel to the tooth surface. Three zones have been identified in the junctional epithelium (Sagle et al, 1979). (A) Apical shows cells with germinative characteristics, (B) Middle zone of major adhesiveness, (C) Coronal zone of greater permeability.
  23. 23. . Differences between Junctional epithelium Oral epithelium The size of the cells relative to the tissue volume is larger Is smaller The intercellular space relative to the tissue volume is layer Smaller The number of desmosomes is more Less Epithelium retepegs and connective tissue papilla are lacking at the junctional epithelium contiss interface Present Non-keratinised Keratinised / parakeratinised Attachment of junctional epithelium to the tooth surface and connective tissue:- The junctional epithelium is attached to the tooth surface epithelial attachment by means of an internal basal lamina which consists of Lamina Lucida and Lamina Densa (which is adjacent to the enamel). To the L. Densa, hemidesmosomes are attached and organic strands from the enamel appear to extend into the lamina densa. The junctional epithelium attaches to the gingival connective by means of an external basal lamina which has the same structure as described before. Functions: 1. It must be noted that unlike the epithelium, connective tissue interface the lamina densa of the internal basal lamina (facing the enamel) has no anchoring fibrils attached to it, which means that the junctional epithelium attaches to it, which means that the junctional epithelium is physically attached to the tooth via
  24. 24. hemidesmosomes (Schroereder and Listgarten). The junctional epithelium attaches to afibrillar cementum when it is present on the crown usually restricted to 1mm of CEJ and the root cementum in a similar manner. 2. The attachment of the junctional epithelium to the tooth is further reinforced by the gingival fibers, which brace the marginal gingival against the tooth surface. For this reason, the junctional epithelium and of the gingival fibers are considered to be a functional unit, refer to as Dentogingival unit. 3. Data has shown that the basal lamina of the junction of epithelial cells resembles that of endothelial and epithelial cells in its laminin content, but junctional epithelium differs in its internal basal lamina, which has no type IV Collagen. These findings indicate that the cells of the junctional epithelium are involved in the production of laminin and play a key role in the adhesion mechanism. 4) They contribute to the defense of the gingiva by the continuous migration of PMN’s through the junctional epithelium. Gingival Connective tissue: The connective tissue of the gingiva is known as the lamina propria (L.P).Lamina propria lies immediately below the epithelium. Consists of 2 layers A: Papillary Layer: which lies to the subjacent epithelium and consists of papillary projections between the epithelial retepegs. B: Reticular Layer: which is contiguous with the periosteum of the alveolar bone. The papillary body comprises a variable dense area of connective tissue papillae ranging from 50-200/mm 2 , the epithelium is thrown to form ridges into which the papilla are interlocked. This interlocking (1) increases the area of contact between the epithelium and L.P (2) facilitates exchange of materials to the epithelium and blood vessels. Composition:
  25. 25. 1) Cells – 5% (mainly fibroblast) 2) Fibers- 60% (mainly collagen) 3) Vessels, nerves and matrix – 35% Cells:- 1)Fibroblasts, 2)Mast cells, 3)Small number of PMN’s for host defense, 4)Macrophages, 5)Monocytes,6)Lymphocyte,7)Plasma cells,8)Endothelial cells, 9)Histocytes 1) Fibroblast – 65% of total cell population, - Morphologic characteristics. Stellate (or) elongated with abundant rough endoplasmic reticulum. - Distribution: Through out L.P - Functions: secretion of fibers and around substance: a) Fibroblast: Synthesize collagen and elastic fibers. b) They synthesized Glycoproteins and Glycosamino glycons c) They regulate collagen degradation. Fibres: The connective tissue fibres are produced by the fibroblast and can be divided into. 1) Collagen fibres 2) Reticulin fibres 3) Oxytalan fibres 4) Elastic fibres. Collagen fibres: (60% of connective tissue volume). The smallest unit of the collagen molecule is known as the Tropocollagen and is synthesized with in the fibroblast. It consists of 3 helical polypeptide chains interwined to form a helix
  26. 26. and each chain consisting of about 1000 amino acids (1/3rd glycine, 20% proline and Hydroxy proline). After the synthesis of tropocollagen molecule it is secreted out from the fibroblast into the extra cellular space. First the tropocollagen molecules are aggregated longitudinally to form protofibrils. These are then laterally aggregated in parallel to form collagen fibrils with an overlapping of tropocollagen molecule by about 25% of their length. The collagen fibres are bundles of collagen fibrils, aligned in such a way that fibres exhibit a cross banding with a periodicity of approximately of 700A0. As the collagen fibres mature, covalent cross-links are formed between the tropocollagen molecules resulting in reduction in collagen solubility. Cementoblast and osteoblasts also possess the ability to produce collagen. Collagen Type I - Forms the bulk lamina propria (91%) Type III - For Tensile strength (8%) Type V - Less than (1%). Functions of gingival collagen fibres; 1) To brace the marginal gingival firmly against the tooth. 2) To provide the rigidity necessary to with stand the forces of mastication without being deflected from the tooth surface. 3) To unite the free marginal gingival with the cementum of root and the adjacent attached gingiva. Gingival fibres are divided into following groups (Grants) Principal group fibres Secondary group
  27. 27. 1) Dento gingival, 1) Transgingival, 2) Dento periosteal, 2) Inter gingival, 3) Alveolo gingival, 3) Inter papillary, 4) Circular, 4) Semi circular, 5) Transseptal group. 5) Periosteal – gingival, 6) Inter circular. Carranza (1996) has classified gingival fibres into 1) Gingivo dental 2) Circular 3) Transeptal 4) Semicircular 5) Transgingival fibres. PRINCIPLE GROUP FIBERS ARE: Origin Insertion Function 1. alveolar gingival Periosteum of Lamina Attaching the gingiva to the
  28. 28. alveolar crest propria alveolar bone. 2. Dento gingival Cementum Lamina propria Support to the gingiva by attaching it to the tooth 3. Dento periosteal Cementum (CEJ) Periosteum of alveolar crest These fibres help to anchor tooth to bone and protect the periodontal ligament. 4. Circular Encircle each tooth in the zone of marginal gingiva and attached gingiva Help to maintain the contour and position of the free gingiva holding it firm against the tooth. 5. Transeptal fibers Cementum of one tooth to the cementum of neighboring tooth, in the inter- proximal areas coronal to the alveolar crest. They protect inter proximal bone and maintain the tooth to tooth contact. Secondary Group fibres are Origin Insertion Function A. Periosteal- gingival Fibers. Periosteum of the alveolar process Attached gingiva Attached the gingiva to the alveolar bone.
  29. 29. B.Interpapillary fibers. Extending facio- lingual direction in the inter- dental gingiva. Vestibular and oral gingival papilla. Provide support to gingival papilla. C.Transgingival fibers. Are arranged between and around the teeth with in the attached gingiva. Attached gingiva. The alignment of teeth in the arch. D. Intercircular fibers. Arisefrom the cementum on distal surface of a tooth extending buccally and lingually around adjacent tooth. Inserted mesial surface of the root of next tooth. Help to stabilize teeth in the arch. E. Inter gingival fibers Are arranged with in attached gingiva in mesio distal direction just beneath the basement membrane. Attached gingiva. Provide support and contour to the attached gingiva. F. Semicircular Extend from mesial surface of the tooth distally and get inserted to the distal surface of the same tooth forming a half circle around each tooth. Inserted on the opposite side of the same tooth. These fibers are almost at the same level as circular fibers & help to support the free margins of gingiva. Other fibres seen as gingival connective tissue; 2) Reticulin fibres:- Are present at the epithelium connective tissue and the endothelium connective tissue interfaces. 3) Oxytalan fibres:- Are present in all connective tissue structures of the periodontium and are composed of long thin fibrils with a diameter of approximate 150A0 function is yet unknown. In the Periodontal ligament, these fibres run
  30. 30. parallel to the root surface in a vertical direction and bend to attach to cervical 3rd of cementum. They are thought to regulate vascular flow. 4) Elastic fibres:- Are present in the connective tissue of the gingiva and PDL only in association with blood vessels. The elastic fibre system is composed of oxytalan, elanulin and elastic fibres distributed among the collagen fibres (carranza, 1996). Matrix: The matrix constitutes the ‘environmental’ for the cell. It is produced by the fibroblast with some components being formed by mast cells and other components are derived from the blood. It composed of protein polysaccharide macromolecules Proteoglycans and glycoproteins. 1. The Proteoglycans:- contain glycosamino glycans (Chondrotin sulfate, Hyaluronic acid) polysaccharide component – always predominant in proteoglycans, polysaccharide components are attached to protein. 2. The glycoproteins:- Protein component is predominant here, mainly fibronectin binds fibroblasts to the fibres and to many other component of the intercellular component. Glycosaminoglycans:- Are large flexible chains of negatively charged molecules, each of which occupies a rather large space. In such a space, smallest molecules (eg, water and electrolytes) can be incorporated, while larger molecules are prevented from entering. Therefore, the proteoglycans act as a molecular filter and in addition, play an important role in regulation of cell movement in the tissue. Due to their structure and hydration, the macromolecular exert resistance towards deformation and are of importance for the resilience of the gingiva. If gingiva is suppressed, the macromolecules become deformed when pressure is eliminated they region their original form.
  31. 31. Blood supply Maxilllary gingiva sub terminal branches Anterior. Anterior superior alveolar artery Lingual Major palatine artery Buccal Buccal artery Posterior Posterior superior alveolar artery Lower gingiva: Anterior buccal. Mental artery Anterior Lingual Inclusive and sublingual artery Posterior Lingual Interior alveolar and sublingual artery Posterior Buccal Interior alveolar and buccal artery 3 Sources of blood supply to gingiva 1) Supra periosteal arterioles: Along the facial and lingual surfaces of alveolar bone from which capillaries extend along the sulcular epithelium and between the rete pegs of the external gingival surface. Occasional branches of the arteriolar pas through the alveolar bone to the periodontal ligament or run over the crest of the alveolar bone. 2) Vessels of the PDL: which extend into the gingiva anastamose with capillaries in the sulcus area. 3) Arteriolar that emerge from crest of the inter dental septa. Nerve supply: Upper gingiva:- Anterior, posterior and middle Superior alveolar branches of Buccal and lingual maxillary nerve, palatal nerves Lower gingiva:- Inferior alveolar branch of mandibular nerve, buccal branch of
  32. 32. Buccal and lingual:branch of mandibular nerve sub-lingual branch of lingual nerve. Receptors are seen as free endings within the papillary layer of the lamina propria. - Touch endings (meissner’s corpuscles) and - Temperature receptors are seen as coiled terminals - Pain receptors are seen as fine fibres in the papilla. All are found in and attached gingiva . The following nerve structures are present in connective tissue. 1) Meshwork of terminal argyrophilic fibres. 2) Meissner’s type tactile corpucles. 3) Krause type end bulbs – temperature. 4) Encapsulated spindle receptors. Lymphatic drainage of the gingiva :- Begins in the lymphatics of the connective tissue papillae and drain into the regional lymph nodes [particularly the sub maxillary group]. In addition, lymphatics just beneath the junctional epithelium extend into periodontal ligament accompany the blood vessels. Functions of gingiva:- 1) The gingiva is located around the necks of each tooth and is structured to resist the forces of mastication. 2) The gingiva coupled with tongue and palate in mastication as a support for bolus of food, food is deflected from the gingiva to the tongue and is in turn, forced between the teeth. 3) The gingiva has sensory function, as it is well innervated with pain, touch and temperature receptors. This capability for sensitivity offers protection. 4) The gingiva acts as a compartment and functions to protect the periodontium from the oral cavity.
  33. 33. Defense mechanism:- 1) The humoral arm which represents the production of gingival fluid. 2) The cellular arm which represents the emigration of neutrophilic granulocytes via junctional epithelium. Both these arms keep a 24 hours, watch on the periodontal health. The gingival fluid is an inflammatory exudate, the amount of fluid is increased when there is inflammation present. It is increased by mastication of coarse food, tooth brushing, ovulation, hormonal contraceptives, smoking etc. Drugs like tetracycline and metronidazole are excreted by gingival fluid. Leucocytes have been found to have phagocytic and killing capacity. Therefore they constitute a major protective mechanism against extension of plaque into the gingival sulcus. Salivary secretions are protective in nature it exerts a major influence on plaque by 1) mechanically cleansing the exposed oral surfaces 2) buffering the acids produced by bacteria 3) controlling bacterial activity. Position of gingiva:- The position of gingival refers to the level at which the gingival margin is attached to the tooth surface. Exposure of the tooth by apical migration of gingival is called gingival recession on 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 apical migration of gingival. Passive eruption is divided into 4 stages. 1) Stage 1: The teeth reach the line of occlusion. The junctional epithelium and base of the gingival sulcus are on the epithelium.
  34. 34. 2) Stage 2: The junctional epithelium proliferates so that part is on the cementum and part is on the enamel. The base of the sulcus is still on the enamel. 3) Stage 3: The entire junctional epithelium in on the cementum and the base of the sulcus is on the CEJ 4) Stage 4: The junctional epithelium proliferates on the cementum. The base of the junctional epithelium is on the cementum, a portion of which is exposed. It is accompanied by degeneration of gingival and PDL fibres and their detachment from the tooth. Age changes in the gingiva:- 1) Diminished keratinization. 2) Reduced or unchanged amount of stippling 3) Increased width of attached gingival. 4) Reduced connective tissue cellularity. 5) Greater amount of intercellular substance 6) Reduced O2 consumption O2 consumption of normal gingiva ---- Q02 1.6 - + 0.37. O2 consumption of skin -------- QO2 1.48 +_ 0.48. 7) An increase or no change in the mitotic index of gingival epithelium. Cuticular structures on the tooth: The term cuticle is defined as thin, acellular structure with a homogenous matrix, sometimes enclosed within clearly demarcated linear borders. Classification: (List garten) 1) Acquired coatings of exogenous origin: Such as saliva, bacteria, calculus, surface stains. 2) Coatings of developmental origin: Are those normally formed as part of tooth development.
  35. 35. such as 1) Reduced enamel epithelium 2) The coronal cementum and 3) The dental cuticle. 1) Reduced enamel epithelium: After enamel formation is completed, the ameloblastic epithelium becomes reduced to 1or 2 layers that remain attached to the enamel surface by hemidesmosomes and a basal lamina. This reduced enamel epithelium consists of post secretary ameloblasts and cells from stratum intermedium of the enamel organ. 2) coronal cementum: In some animals the reduced enamel epithelium disappears very rapidly, there by placing the enamel in contact with the connective tissue. Connective tissue cells then deposit a thin layer of cementum known as coronal cementum on the enamel. In humans, thin patches of afibrillar cementum may be seen in the cervical ½ of crown. 3) The dental cuticle: consists of a layer of homogeneous organic material of variable thickness, overlying the enamel surface, it is non mineralized and is not always present. Studies have shown the dental cuticle to be proteinaceous and it may be an accumulation of tissue fluid components. Properties, functions and defense mechanisms. As the gingival 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: A) It protects the supporting tissue from the oral environment. It is subjected to friction and pressure in the masticatory process. It’s densely collagenous lamina propria, peripheral sensory innervations and keratinization help in the adaptation to these physical requirements. B)Gingiva is a mucostable tissue because, of its firmness, scalloped contour, close adaptation and attachment to the understanding structures. C) Gingival tissue fulfill the functions of sensitivity and resistance
  36. 36. II As part of the periodontium:- A) The gingiva exhibits functional properties. 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 generature forces resulting in mesial drift. B). It maintains gingival and periodontal health by means of various defense mechanisms operating within the gingival tissue. 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 epithelium - Leukocytes. 3) The gingival sulcular fluid contains proteins, specific antibodies and antigens, enzymes and cellular elements. leucocytes have through the gingival fluid leucocytes have been found to have phagocytic and killing capacity. 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 24hr periodicity with highest and lowest rates. Occurring in the morning and evening respectively, The mitotic rate is higher in non-keratinized area and increased in gingivitis. Clinically the surface of attached gingiva resembles that of an orange peel. It is characterized 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 3.5 mm in depth. More on facial aspect of maxillary anterior and less on
  37. 37. anterior mandibular. Stippling is a form of adaptive reinforcement on specialization for function loss of stippling is a common sign of gingival disease. Clinical considerations :- When we performing dental treatment like cavity preparation and crown cavity proper protection of gingival is necessary. If there is any damage of the gingival tissue it sometimes will lead to periodontal disease. While preparing crown just below free gingival care must be taken not to damage attached gingival tissue. Proper contact should be maintained to prevent food lodgment 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. CORRELATION OF NORMAL AND CLINICAL MICROSCOPE FEATURES
  38. 38. Appearance in healthy gingiva Microscopic features Changes in disease/ clinical appearance Cause for change A) color Uniformly pale pink/ coronal pink. melanin pigmentation occurs as a diffuse, deep purplish discoloration (or) As irregularity shaped brown and light brown patches a) vascular supply b)Thickness and keratinisation of epithelium presence of pigment containing cells Chronic bluish pink / bluish red. - Vessels - Engorged - Blood flow sluggish - Venous return impact B). Size Corresponds to the sum total of bulk of acellular and inter cellular elements & their vascular supply. Enlarged -Edematous inflammation fluid cellular exudates hemorrhage. C). Shape Marginal gingival knife edge, follows a curved line around the tooth Governed by the proximal tooth surface and the location and shape of gingiva embrasure Rolled/ Rounded Inflammation changes edema or fibrous
  39. 39. D). consistency Firm and resilient E).Surface texture The gingiva presents a textured surface with stippling like that of an orange peel(attached gingiva). Marginal gingiva is not stippled The collagenous nature of lamina propria and its contiguity with the periosteum of the alveolar bone. Alteration of rounded protrusion & depression in gingival surface. Soft,spongy red color. smooth and shiny surface when pressed with a probe. Absent in infancy and old age Edematous fluid between cells in the connection. Summary and conclusion Hence during clinical practice, focus should be placed not only on the hard tissues, but also on the prime structures of the periodontium especially the gingiva. REFERENCES:  Textbook of Oral Histology and Embryology - Orbans.  Clinical Periodontology – Glickman.

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