Gingiva PDF

Gingiva Dr /Abdel-latif Galal Lecturer of oral Medicine& Periodontology  : Masticatory mucosa: Masticatory mucosa covers the gingiva and hard palate. Gingiva or Gum : Thick (250µm) keratinized epithelium (either orthokeratinized or parakeratinzed) with no submucosa....

Gingiva Dr /Abdel-latif Galal Lecturer of oral Medicine& Periodontology  : Masticatory mucosa: Masticatory mucosa covers the gingiva and hard palate. Gingiva or Gum : Thick (250µm) keratinized epithelium (either orthokeratinized or parakeratinzed) with no submucosa. It extends from dentinogingival junction to the alveolar mucosa.  It develops from the union of oral epithelium and reduced enamel epithelium of the developing tooth  Gingiva clinically can be classified into 3 parts Free gingiva, attached gingiva and interdental papilla.  A -Free gingiva (unattached or marginal gingiva)  It is that part of the oral mucosa that surrounds the necks of the teeth. It is differentiated apically from the attached gingival by the free gingival groove.  The inner side of it forms the gingival sulcus  The free gingival mucosa is composed of stratified squamous epithelium that may be keratinized, or parakeratinzed B -Attached gingiva  It’s firm , resilient and tightly bound to underlying periosteum of alveolar bone. The attached gingiva lies between the free gingival groove and the alveolar mucosa.  The junction of the attached gingiva and the alveolar mucosa is called mucogingival junction. The color of the marginal and attached gingiva is generally described as "coral pink“. In healthy mouth attached gingiva shows stippling (orange-peel appearance) (depression & elevation which correspond to epi. ridges & connective tissue papilla) C -Interdental papilla  It’s occupies the gingival embrasure (which is the interproximal space between two adjacent teeth).  It’s surface is triangular in 3 dimension  The color of the gingiva is generally coral pink but it becomes red in inflammation, sometimes it’s brown because of increase melanin pigmentation. Interdental Papilla (arrow) Gingival Epithelium Stratified squamous epithelium: oral or outer epithelium sulcular epithelium junctional epithelium /epithelial attachment.  Oral or Outer Epithelium The oral or outer epithelium covers the crest and outer surface of the marginal gingiva and the surface of the attached gingiva. It is keratinized or parakeratinized Gingival Connective Tissue : There are three types of connective tissue fibers are collagen reticular elastic. Gingival sulcus Is a groove developed between the tooth surface and the free gingiva. It is lined with epithelium of non keratinized type derived from oral ep. Called sulcular epithelium.  Extends from free gingival margin to the junctional epithelium.  Gingival sulcus has a depth 0.5 – 3 mm; any depth greater than 3 mm can be considered a pathologic state ( periodontal pocket ). Sulcular epithelium The sulcular epithelium lines the gingival sulcus. It is a thin, nonkeratinized, stratified squamous epithelium without rete pegs and extends from the coronal limit of the junctional epithelium to the crest of the gingival margin. The sulcular epithelium good resistance to mechanical forces and impermeability to fluid and cells. Junctional epithelium:  Stratified squamous non-keratinizing epithelium ; 3-4 layers thick in early life, but with age to 10-20.  More permeable than sulcular epithelium  Junctional epithelium provides the attachment of the gingival epithelium to the tooth in the cervical area, by the gingival fibers; For this reason, both are considered a functional unit, dentogingival unit. Junctional epithelium is firmly attached to the tooth surface, forming an epithelial barrier against plaque bacteria. Disturbances of epithelial attachment results in deepening of the sulcus which is a sign of gingival/periodontal disease  Root Development Cervical loop Hertwig’s epith. root sheath Odontoblast differentiation Dentin formation Disintegration of root sheath Cementoblast differentiation Root sheath development  The development of the roots begins after enamel and dentin formation has reached the future cementoenamel junction.  Once crown formation has completed, epithelial cells of the inner and outer enamel epithelium proliferate from the cervical loop of the enamel organ to form a double layer of cells known as Hertwig's epithelial root sheath (HERS).  This sheath initiates formation of dental root and determines the number, shape, length and dimensions of the roots.  The first formed part of the root sheath bends upward at a 45 angle to form a disc like structure ,the rim of this disc is called the epithelial diaphragm.  The epithelial diaphragm will maintain constant size of the primary apical opening which finally becomes the apical foramen.  Bell stage Dental follicle Epithelial diaphragm  Reduced enamel epithelium \ Enamel space Dental Dental follicle Epithelial root sheath cells Epithelial diaphragm  Single root formation Growth of HERS like a cuff or tube around the cells of dental papilla Cells of dental papilla to differentiate into odontoblasts Formation of root dentin HERS cells separate from the surface of root dentin HERS cells then beings to migrate away from the root surface Cells differentiate into cementoblasts and secrete cementum Root elongation continues progressively.As the root lengthen, the compensatory movement of eruption provides space for further root development.  nnrcn A. Root elongation. B. Tooth eruption  Formation of multi- rooted teeth Two Root Root trunk Zone of initial contact of epithelial extensions * The root trunk of molars is formed like single rooted tooth. * At the bifurcation area, the epithelial diaphragm produces 2 or 3 tongue- like processes in case of 2 rooted & 3 rooted teeth. * The processes grow towards each other & fuse dividing the wide root trunk into 2 or 3 roots. Each root proceeds in development as in single rooted tooth.  Fate of epithelial root sheath The epithelial sheath(HERS) disintegrates as root formation progresses. As the root sheath fragments, it leaves behind a number of discrete clusters of epithelial cells, separated from the surrounding connective tissue by a basal lamina, known as the epithelial cell rests of Malassez. The epithelial rests of Malassez are found in the periodontal ligament(PDL) through out the life. Sometimes when there is chronic inflammation the epithelial cell rest of Malassez proliferate into cysts and tumors.  Root formation Anomalies 1. Lateral canals: If continuity of HERS were broken before dentin formation, result in accessory root canal connecting PDL with main root canal which may occur in the apical third of teeth. 2. Exposed dentin: If HERS does not degenerate at proper time remains adherent to dentin, no cementum formation will occur, result in expose dentin, particularly in cervical region and may cause cervical sensitivity later in life. 3. Enamel pearls: HERS may also remain adherent to the dentin in the cervical area near the furcation zone, the inner cells of HERS may differentiate into functional ameloblasts and produce enamel droplets known as E. pearls found between the roots of permanent molar E 4. Dilacerations: If the HERS dislocated after partial root mineralization, the remaining of the root may eventually be bent or twisted resulting in a condition called "dilacerations" or root distortion. This seen in permanent teeth usually.