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Gingiva

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Gingiva

  1. 1. The periodontium (peri-around, dontium-tooth, greek) consists of investing and supporting tissues. The investing tissue of the periodontium is known as the GINGIVA. It is the most peripheral portion of periodontium at large. According to the Dorland Medical Dictionary, the word gingiva means the ‘gum of the mouth’. It is that part of the oral mucosa overlying the crown of unerupted teeth and encircling the necks of these that have erupted, serving as the supporting structure for the subadjacent tissues. DEFINITIONS 1. CARANZA Is the part of oral mucosa that covers the alveolar processes of jaw and surrounds the neck of teeth. 2. SCHROEDER It is a combination of epithelium and connective tissue and is defined as that portion of oral mucous membrane, which in complete post- eruptive dentition of a healthy young individual, surrounds and is attached to the teeth and the alveolar processes. 3. GRANT Is the part of oral mucous membrane attached to the teeth and the alveolar processes. 1
  2. 2. 4. LINDHE Is that part of masticatory mucosa covering the alveolar processes and the cervical portions of teeth. FUNCTIONS As the gingiva represents both the masticatory mucosa as well as the most peripheral part of the periodontium, its functions are two fold. I] As part of the oral mucosa It protects the supporting tissues from the oral environment. a) As part of oral mucosa, it is subjected to friction and pressure in the masticatory process. Its densely collagenous lamina propria, peripheral sensory innervation and keratinization help in the adaptation to these physical requirements. b) It is a mucostable tissues because of its firmness, scalloped contour, close adaptation and attachment to the underlying structures. c) Gingival tissues fulfill the functions of sensitivity and resistance. II] As part of the periodontium The gingiva exhibits functional properties: a) It ensures dental arch linkage and controls the positioning of teeth in the horizontal plane by means of its supra-alveolar fibre apparatus. These fibres along with those of PDL secure teeth against rotational forces and generate forces resulting in mesial drift. 2
  3. 3. b) It maintains gingival and periodontal health by means of various defense mechanism operating within the gingival tissues. This peripheral defense action of gingiva has two arms: 1. The humoral arm which represents the generation of gingival fluid. 2. The cellular arm which represents the continuous irrigation of neutriphilic granulocytes via the junctional epithelium. Both these arms keep a 24 hour watch on the periodontal health. Development Unlike, the other tissues of the periodontium which are derived from the ectomesenchymal dental follicle, the gingiva is a derivative of mesoderm. According to Schroeder, the shape, topographical distribution and width of the gingiva are functions of the presence and position of erupted teeth. He also says that, there are reasons to assume that the gingival tissues exist and develop as a site specific portion of the oral mucous membrane prior to the eruption of deciduous teeth. Thereafter, the gingiva although increasing size serves both deciduous and permanent teeth. 3
  4. 4. Normal Clinical Features Gingiva is divided into: Oral part Vestibular part Anatomically, it has been divided into: - MARGINAL gingiva - ATTACHED ginigiva Pyramidal - INTERDENTAL gingiva Col A] Marginal gingiva / Free gingiva / Margio Gingivalis Definition It is the terminal edge or border of the gingiva surrounding the teeth like a collar. Figure It is demarcated from the adjacent attached gingiva by a shallow linear depression – the free gingival groove. This is about 1mm wide and forms the soft tissue wall of the gingival sulcus. According to Schroeder, the term ‘free gingiva’ is a clinical designation and relates to the clinical property of the gingival rim. 4
  5. 5. B] Attached Gingiva It is continuous with the marginal gingiva. It is firm, resilient, and tightly bound to the underlying tissues of the alveolar bone. On the facial aspect, the attached gingiva extends to the relatively loose and movable alveolar mucosa from which it is demarcated by the mucogingival junction (3 M G Lines) Facial maxillary Facial mandibular Lingual mandibular # Lingual maxillary is not seen as there is not alveolar mucosa on the palate and the palatal tissue is firmly attached to the bone. Width of the attached gingiva Is defined as the distance between the mucogingival junction and the projection on the external surface of the bottom of the gingival sulcus / periodontal pocket. It is generally greatest in the incisor region (3.5 – 4.5mm in maxilla and 3.3 – 3.9mm in mandible) and less in the posterior region with least in the 1st premolar area (1.9mm in maxilla and 1.8mm in mandible). The width of the attached gingiva increases with age and supraerupted teeth. Reduced / Absent Attached gingiva may be due to: - base of the pocket is close to the mucogingival line. 5
  6. 6. - frenal / muscle attachments that encroach on pockets and pull them away from the tooth surface. - denudation of root surfaces. Adequacy of the attached gingiva can be determined by the TENSION TEST which consists of retracting the cheeks and lips laterally with fingers and checking if such tension polls the marginal gingiva from the teeth. Reduced width of attached gingiva can be corrected with mucogingival surgeries. C] Interdental Gingiva It occupies the gingival embrasure, which is the interproximal space beneath the area of tooth contact Types: Pyramidal Col  Where there is one papilla with its tip immediately beneath the contact point.  Which represents as a depression that connects a fascial and a lingual papilla and conforms to the shape of interproximal contact. 6
  7. 7. Various anatomic variations of the interdental col in the normal gingiva and after gingival recession 1) Mandibular anterior 2) Mandibular posterior GINGIVAL SULCUS - Is the shallow space / crevice around the tooth bounded by the surface of the tooth on one side and epithelium lining the free margin of the gingiva on the other. - It is V-shaped and rarely permits the entrance of a periodontal probe. Under normal circumstances, the depth is 0 In histologic sections – 1.8mm. The probing depth is 2-3mm 7
  8. 8. GINGIVAL FLUID / SULCULAR FLUID (GCF)  The gingiva sulcus contains a fluid that seeps into it from the gingival connective tissue through the thin sulcular epithelium. Function of GCF: - cleanses material from the sulcus. - Contains plasma proteins that may improve adhesion of the epithelium to the tooth. - It also possesses antimicrobial properties. - It exerts antibody activity in defense of the gingiva. 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 remnants of dental organ)  Reduced enamel epithelium (R.E.E.). Between the R.E.E. and the overlying oral epithelium, is the connective tissue that supports R.E.E. and the oral epithelium. R.E.E.  OL and IL OL – flattened cells – remnants of dental organ (outer layer). IL Ameloblasts (inner layer) 8
  9. 9. When tooth eruption begins, this connective tissue breaks down. In response to these degradative changes, the cells of OL of R.E.E. and basal cell of oral epithelium proliferative 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 reduced enamel epithelium, the epithelial component of the dentogingival junction 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 tip of the cusp emerges, initiating an acute inflammatory response in the already altered c.t. supporting the epithelium. The clinical manifestations of this inflammatory response is called teething. Once the tip of the cusp emerges, oral epithelium cells begin to migrate partially over the reduced enamel epithelium, in an apical direction 9
  10. 10. and at this time, the attachment of the gingival epithelium to tooth is maintained. This is primary epithelial attachment (by ameloblasts). Because of the continuing cell division, the ameloblasts are eventually displaced by the newly formed daughter cells. As the overgrowing epithelial cells from the cuff stratify, they further separate the cells of the transformed dental epithelium from the nutritive supply, with consequence that these latter cells degenerate and create a Gingival Sulcus. NORMAL MICROSCOPIC FEATURES The gingiva consists of a central core of c.t. (lamina propria) covered by stratified squamous epithelium. Gingival Epithelium From the morphologic and function points of view 3 different types are seen. Oral / Outer Sulcular Junctional Functions To protect the deep structures while allowing a selective interchange with the oral environment (achieved by proliferation and differentiation of keratinocytes). 10
  11. 11. Later The principle cell is the keratinocyte. - Proliferation takes place by mitosis. - Differentiation involves the process of keratinization. The main morphologic change is the progressive flattening of the cell. 3 types of keratinization can be seen: Histologically, a keratinized epithelium shows a number of distinct layer. I] St Corneum It is the surface of very flat eosinophilic cells. II] St Granulosum Larger flattened cells that contain kerato-hyaline granules. The upper most layer of stratified spi contains numerous granules called keratinosomes / odland bodies. 11
  12. 12. III] St Spinosum / Prickle cell Layer Larger elliptical / spheroidal cells. When prepared for histologic sections, these cells shrink away from one another remaining in contact only at patients known as intercellular bridges / desmosomes. IV] St Basale Proliferative layer. 3 types Ortho Keratinocyte Para Keratinocyte Non-keratinocyte - Complete keratinocyte - No nuclei in st corneum - Well defined St. granulosum e.g. layers of outer gingival epithelium - Partial / incomplete keratinocyte - Pyknotic nuclei in st corneum - Keratinohyaline granules - No st granulosum e.g. most areas of gingival epithelium - No keratinocyte - No corneum / granulosum Keratinization The prot syn during maturation process – keratolinin and involved in form an envelope below the cell membrane (chemically resistant structure). As the cells reach the corneum keratin or disappear and give rise to a protein – fillagirin which forms the matrix of the most differentiated epithelial cells – CORNEOLYTE. 12
  13. 13. Cell type Level in epithelium Functions 1. Melanocyte 2. Langerhans cells 3. Merkels cells Basal Predominantly suprabasal Basal Synthesis of melanin pigment Regulatory cell Macrophage (contain Birbeck’s granules) Tactile perception Both epithelial proliferation and maturation are needed for continuous cell renewal to maintain structural integrity. The control over these two processes is mediated by substance produced by maturing epithelial cells – CHALONES which acts by –ve feedback mechanism. STRUCTURE AND METABOLIC CHARACTERISTICS OF GINGIVAL EPITHELIUM I] Oral / outer epithelium It covers the crest / outer surface of the marginal gingiva and the surface of the attached gingiva. It is keratinized / parakeratinized or present various combinations of these conditions. The prevalent surface is however parakeratinized. - In orthokeratinized areas  Keratins K1, K2 and K-10, K-12 which are specific for epidermal differentiation are expressed with high intensity. 13
  14. 14. - K6 and K16  characteristic of highly proliferative epithelium K1, K2, K-10, K-12 – expressed with low intensity in parakeratinized area. These also express K-19 which are absent from Ortho keratinized area. II] Sulcular epithelium - Lines the gingival sulcus. - It is a thin, non-keratinized squamous epithelium without retepegs, which extends from the coronal limit of junctional epithelium to the crest of the gingival margin. - It shows cells and with hydropic degeneration. - It contains keratins K4 and K13, also expresses K-19. It lacks stratum granulosum and corneum, cytokeratins K1 and K2 and K10- K12 and also lacks Merkels cells. It has the potential to keratinize, if: a) It is reflected and exposed to the oral cavity. b) The bacterial flora of the sulcus is totally eliminated. These findings suggest that the local irritation of the sulcus (due to its contact with tooth) prevents sulcular keratinization. 14
  15. 15. Functions of sulcular epithelium It acts as a semi-permeable membrane three which injurious bacterial pass into the gingiva and three which tissue fluid from the gingiva seeps into the sulcus. III] Junctional epithelium - Consists of a collar-like band of stratified squamous non- keratinizing epithelium. a) It is 3-4 layers thick in early life, but it increases with age to 10-20. b) The length ranges from 0-25 – 1.35 mm. c) It is widest in its coronal portion (15-20 cell layers) but becomes thinner towards the CEJ. d) It expresses K-19 and the stratification specific cytokeratins K5 and K14. Histology of junctional epithelium Is a continuous self-renewal structure and is continuously renewed through cell division occurring in the basal layer. The cells migrate to the base of the gingival sulcus, from where they are shed. Cells are arranged in 2 strata Basal Suprabasal Both are flattened with their long axis 11 to the tooth surfaces 15
  16. 16. 3 zones have been identified in the junctional epithelium Apical Middle Coronal Shows cells with germinative characteristics Zone of major adhesiveness Zone of greater permeability Attachment of junctional epithelium is attached to the tooth surface (epithelial attachment) by means of an internal basal lamina (300-400 A° thick and lies 400 A° beneath the epithelial basal layer) laminin, basement membrane glycoprotein. Lamina lucida lamina densa (adjacent to the enamel) It attached to the connective tissue by means of an external basal lamina. Functions - Unlike the epithelial connective tissue interface, the lamina densa of the internal basal layer (facing the enamel) has no anchoring fibrils 16
  17. 17. attached to it, which means that the junctional epithelium is physically attached to the tooth via the hemidesmosomes (Schroerder). - The attachment of the junctional epithelium to the tooth is further reinforced by the gingival fibres which brace the marginal gingiva against the tooth surface for this reason. Junctional epithelium and gingival fibres are a function unit DENTOGINGIVAL UNIT Difference between Junctional epithelium Oral epithelium - The size of the cells relative to the tissue volume is larger. - The intercellular space relative to the tissue volume is larger. - The number of desmosomes is smaller. - Epithelial retepegs and connective tissue papillae are lacking at the junctional epithelial c.t. interface. - Non keratinized. - Is smaller. - Is smaller. - Is larger. - They are present. - Keratinized / parakeratinized. 17
  18. 18. GINGIVAL CONNECTIVE TISSUE Known as lamina propria (2 layers) Papillary layer Reticular layer Lies to the subjacent epithelial and consists of papillary projections between the epithelial retepegs. Which is contiguous with the periosteum of the alveolar bone. The c.t. consists of : - Cells – 5% (mainly fibroblasts). - Fibres – 60% (mainly collagen). - Vessels, nerves and matrix – 35%. Cells - Fibroblasts are stellate / elongated with abundant rough E.R. - They are distributed throughout the lamina propria. The other cells present are: Histocytes Macrophages. Monocytes 18
  19. 19. Mast cells Polymorphonuclear leukocytes Neutrophil Lymphocyte Plasma cells FIBRES - The connective tissue fibres are: Collagen Reticulum Oxytalan Elastic Collagen – 65% of C.T. volume Tropocollagen (smallest unit of a collagen are aggregated longitudinally to form molecule) after synthesis, it is secreted out from the fibroblasts into extracellular space. Protofibril laterally aggregates to in II form collagen fibrils with an overlapping of tropocollagen mole by about 25% of their lengths. - These are bundles of collagen fibrils, aligned in such a way that fibres exibit a cross-binding. 19
  20. 20. Collagen Type I - Forms the bulk of lamina propria and provides tensile strength. - Gingival collagen fibres – consists of Type I collagen. Functions: - To brace the marginal gingiva firmly against the tooth. - To provide rigidity necessary to without and the forces of mastication without being deflected from the tooth surfaces. - To unlike the free marginal gingiva with the cementum of the root and the adjacent attached gingiva. Reticulum - Are present at the epithelial connective tissue and the endothelium c.t. interface. Oxytalan - are present in all c.t. structure of the periodontium and are composed of long thin fibrils. They regulate vascular flow. In the PDL, these fibres run 11 to the root surfaces in a vertical direction and bend to attach to cervical 3rd of cementum. - Are present in all C.T. of gingiva and periodontal only in association with the blood vessels. 20
  21. 21. GINGIVAL FIBRES I] According to Grants a) Dentogingival group : These fibres extend from the cementum apical to the junctional epithelium and coarse laterally and coronally into the lamina propria of the gingiva. b) Alveogingival : Arise from the alveolar crest and insert coronally into the lamina propria. c) Circular These encircle the teeth. d) Transeptal Is a group of prominent horizontal fibres that extend interproximally between adjacent teeth. e) Dentoperiosteal Extends from the tooth passing over the alveolar crest to blend with fibres of the periosteum of the alveolar bone. 21
  22. 22. f) Semicircular group Run from the distal / mesial root surface of a tooth and extend around the oral / vestibular surface to insert on the opposite side of the same tooth. g) Transgingival From the proximal root surface they radiate three the embrasures to blend with the fibres of the oral / vestibular surfaces. h) Intergingival They run 11 to the dentition on oral / vestibular surfaces. II] Carranza (1996) - Gingiovodental. - Circular. - Transeptal. - Semicircular - Transgingival 22
  23. 23. MATRIX - Constitutes the environment for the cell. It is produced by fibroblasts and is composed of protein polysaccharides and macromolecules. Proteoglycans Glycoproteins BLOOD SUPPLY 3 sources of blood supply to gingiva (Carranza 1996). a) Supra-periosteal arterioles Along the fascial and lingual surface of the alveolar bone, from which capillaries extend along the sulcular epithelial and between the retepegs of the external gingival surface. b) 2 vessels of the PDL – which extend into the gingiva anastomose with capillaries in the sulcus area. c) Arterioles which emerge from crest of the interdental septa. Nerve supply region Innervation - Upper gingiva Anterior, post and middle supraalveolar branches of maxillary nerve, palatal nerves. Lower gingiva buccal and lingual Infection alveolar branch of mandibular nerve, buccal branch of mandibular nerve, sublingual branch of lingual nerve. 23
  24. 24. Lymphatic drainage - Brings in the lymphatics of the C.T. papillae. It progresses to the regional lymph nodes. 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 - Like saliva, calculus and surface stains. 2) Coatings of developmental origin - Are those normally formed as part of tooth development after enamel form is completed, the ameloblastic epithelial becomes reduced to 1-2 layers that remnants attached to the enamel surfaces like: a) R.E.E. b) Coronal cementum. c) Dental cuticle In animal, the R.E.E. disappear very rapidly thereby placing the enamel in contact with c.t. whose cells then deposit a thin layer of 24
  25. 25. cementum. In humans, a thin layer of afibrillar cementum may be seen on the cervical % of crown. Consists of a layer of homogenous organic material of variable thickness (0.25µm), overlying the enamel surface. It is non-mineralized and not always present. Studies have shown the dental cuticle to be protein across and it may be an accumulation of tissue fluid components. 25
  26. 26. CO-RELATION OF NORMAL CLINICAL FEATURES AND MICROSCOPIC FEATURES Appearance in health Changes in disease / clinical appearance Causes for changes 1. Colour Uniformly pale pink / coral pink Variations in pigmentation related to race a) Chronic – bluish pink / bluish red - Vessels engorged - Blood flow sluggish and - Venous return impaired 2. Size Not enlarged fits snugly around the tooth Enlarged - Edematous inflammatory fluid, cellular exudates hemorrhage 3. Shape a) Marginal gingiva : Knife edge, follows a curved line around the tooth Rolled / rounded Inflammation changes, edema or fibrosis 4. Consistency Firm Soft, spongy, red colour, dents readily when pressed with a probe, smooth and shiny surface Edematous fluid between cells in the connective tissue 5. Surface texture Represents that of an orange pell and is known as stippling. The attached gingiva is stippled – not the marginal. It varies with age, is absent in infancy increase till adulthood and disappears in old age. It is produced by alternate protruberances & depressions in the gingival surfaces. 26
  27. 27. - Exposure of the tooth by the apical migration of gingiva is called gingival recession / atrophy. Physiologic Pathologic - occurs with age - When excessive exposure occurs. 27

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