The Gingiva - PDF

THE NORMAL PERIODONTIUM THE GINGIVE DR. NAWAL KHALIFA BABIKIR THE GINGIVA It is part of the oral mucosa, it covers the alveolar processes of the jaws and surrounds the teeth. ( but is not adherent to it). It extends to mucogingival junction. The width varies from 1-9 mm( in total). The spac...

THE NORMAL PERIODONTIUM THE GINGIVE DR. NAWAL KHALIFA BABIKIR THE GINGIVA It is part of the oral mucosa, it covers the alveolar processes of the jaws and surrounds the teeth. ( but is not adherent to it). It extends to mucogingival junction. The width varies from 1-9 mm( in total). The space between the marginal gingiva and the external tooth surface is termed as the gingival sulcus.  The gingiva is divided anatomically into: Marginal. Attached Interdental areas. MARGINAL GINGIVA The free gingiva is a knife edge part of gingiva. located coronal or above the CEJ, surrounding the tooth in a turtleneck or collar like manner. MARGINAL GINGIVA It’s the coronal extension of the gingiva on the buccal & lingual aspects of the teeth. It is demarcated from the attached gingiva by ( free gingival groove). About 1 mm in width. It forms the soft tissue wall of the gingival sulcus.  Gingival sulcus: is the shallow crevice or space around the tooth neck. Boundaries: tooth surface &epithelium lining the free margin. The depth of the gingival sulcus is an important clinical parameter. Ideally it should be zero mm, but the depth of a clinically normal sulcus is 2-3mm. Development of Gingival Sulcus ATTACHED GINGIVA: It is firm, resilient, extend from the FGG( free gingival groove) to mucogingival junction. The width of gingival margin is an important clinical parameter. It differs in different areas of the mouth. Greatest in incisor area (3.5-4.5to 3.3-3.9)mm , narrower in post. area (1.8-1.9)mm. Increased by age, and in supraerupted teeth. INTERDENTAL GINGIVA It is the part of the gingiva fill in the embrasure beneath the contact point. It is either pyramidal or can have a col shape; this determined by: i. Tooth contact. ii. The width of neighbouring teeth. It is completely missed in case of diastema MICROSCOPIC FEATURES Histologically, the gingiva composed of: Overlying Stratified Squamous Epithelium(SSE). Core of connective tissue( lamina propria).  A dividing line between the two is a structureless layer called the basement membrane. Usually irregular, this results in projections of lamina propria called connective tissue papillae which interdigite with downward projections of epithelium into the lamina propria called rete pegs or epithelial ridges  The epithelium is joined to underlying connective tissue by basal lamina which consist of lamina Lucida and lamina densa. Lamina lucida composed mainly of glycoprotein laminin. lamina densa is composed of type IV collagen. Basal lamina acts as barrier to particulate matter. Width of 300-400 A° ( A metric unit of length equal to one ten billionth( 12 zeros) of a meter). GINGIVAL EPITHELIUM: It consist of a continuous lining of SSE ( Stratified Squamous Epithelium), it have three different areas: 1. The oral epithelium: extends from the gingival margin to the mucogingival junction. 2. The sulcular epithelium facing the tooth. 3. The junctional epithelium, apical to the sulcular epi, the gingiva is joined to the tooth.  The principal cell type of the gingival epithelium, is the keratinocyte. Other cells found in the epithelium are the clear cells or non keratinocytes, which include the: Langerhans cells, Merkel cells melanocytes ORAL EPITHELIUM: It is 0.2-0.3 mm in thickness. Ortheratinized or parakeratinized. degree of keratinization varies in different areas. Contains rete pegs. The degree of gingival keratinization diminishes with age and the onset of menopause. SULCULAR EPITHELIUM: Lining the gingival sulcus. Thin , without rete pegs. Non- keratinized. lacks granulosum and corneum strata. Normally have no Merkel cells. Have the potential to keratinize. JUNCTIONAL EPITHELIUM: It is 3-4 layers thick and increase by age ,but the number of layers increases with age to 10 or even 20 layers. Composed of 2 strata. The length ranges from 0.25-1.35mm. Formed by the confluence( flowing together) of the oral epi. and the reduced enamel epi. Junctional epithelium expresses K 19.  The principle cell type is the KERATINOCYTE, the other cells in the epi. are the clear cells which include the: Langerhans cells, Merkel cells & melanocytes. Keratinocytes provide the main function of the oral epi.( which is the protective in nature), by the means of proliferation and differentiation.  Proliferation of keratinocytes takes place by mitosis in the basal layer and less frequently in the suprabasal layers. Differentiation involves the process of keratinization. The main morphologic changes are : (1 ) progressive flattening of the cell with an increasing prevalence of tonofilaments. (2) intercellular junctions coupled to the production of keratohyaline granules. (3) disappearance of the nucleus.  Types of keratinization: 1. Orthokeratinization. 2. Parakeratinization. 3. non-keratinization.  Keratinocytes are interconnected by means of desmosomes. They are a structure on the cell periphery. Less frequently they may connect by tight junctions. Cytoplasmic organelle concentration varies among different epithelial strata. OTHER EPITHELIAL CELL: Melanocytes: dendritic cells , located at basal and spinous layers, they synthesize melanin. Langerhans Cells: dendritic cells , located at suprabasal layers, absent from junctional epithelium. Merkel cells: found at basal layer, harbour the nerve endings, function as tactile preceptors. RENEWAL OF GINGIVAL EPITHELIUM The oral epithelium undergoes continuous renewal. The mitotic rate is higher in nonkeratinized areas and is increased in gingivitis, without significant gender differences. The following have been reported as turnover times for different areas of the oral epithelium in experimental animals: Palate, Tongue, and Cheek, 5 to 6 days; Gingiva, 10 to 12 days. Junctional epithelium, 1 to 6. FUNCTION OF GINGIVAL EPITHELIUM Provide a physical barrier to infection and the underlying gingival attachment. Epithelial cells play an active role in innate host defense by responding to bacteria in an interactive signaling. For example, epithelial cells may respond to bacteria by: Increased proliferation. Alteration of cell-signaling events. Changes in differentiation and cell death. Alteration of tissue homeostasis. CONNECTIVE TISSUE Mainly formed by collagen fibers 60%, fibroblast, vessels ,nerves, and matrix 35%. Consist of two layers: 1. Papillary layer. 2. Reticular layer. Have a cellular and extracellular compartment. The cellular : I. Fibroblast are the main cells of the connective tissue, it forms collagen and elastic fibers. II. Mast cells. III. Plasma cells, lymphocytes and neutrophils.  The ground substance: It is composed of : Proteoglycans (hyaluronic acid and chonroitin sulfat). Glycoprotein mainly fibronectin, & laminin. The Fibers: 1. The main is collagen fiber type I and IV. The former form the bulk of the lamina propria and provide the tensile strength( capable of being shaped or bent or drawn out ). 2. Elastic fibers ( oxytalan, & elastin).) GINGIVAL FIBERS: The gingival fibers are arranged in groups. 1. The dentogingival group: they originate from the cementum extend in fanlike conformation toward the crest and outer marginal gingiva. Extend to the periosteum of the facial and lingual bone. Interdentally fibers extend toward the crest of gingiva. 2. Circular group: course through the connective tissue of marginal and interdental in ring like fashion. 3.Transseptal group: located interproximally, form horizontal bundles extend between the cementum of approximating teeth. GINGIVAL FIBERS FUNCTIONS: 1. To brace the marginal gingiva firmly against the tooth. 2. To provide the rigidity necessary to withstand the forces of mastication without being deflected away from the tooth surface. 3. To unite the free marginal gingiva with the cementum of the root and the adjacent attached gingiva. BLOOD& NERVE SUPPLY: Blood supply is provided through three sources: 1. Supraperiosteal arterioles. 2. Vessels of the periodontal ligament. 3. Arterioles that emerge from the crest of the interdental septa. Nerve supply , by the fifth cranial nerve. CLINICAL FEATURES OF NORMAL GINGIVA Color: Coral pink or salmon red, depends on the: 1. Degree of vascularity. 2. Thickness of keratinization. 3. Presence of pigmented cells. SHAPE: HAVE A KNIFE EDGE WITH THE TOOTH. CONTOUR: NORMALLY FOLLOW THE CONTOUR OF THE TOOTH, BUT USUALLY SCALLOPED.  Consistency: Firm, resilient. Surface texture: Orange-peel( stippled) appearance. Position: The position of the gingiva refers to the level at which the gingival margin is attached to the tooth. Look for the position of marginal gingiva. Features Children Adults Gingival color More reddish Coral pink contour Free gingival marginrounded Gingival margin- knife edge Consistency Flabby due to less CT Firm and resilient density and lack of organized collagen fiber bundles Surface texture Stippling absent in infancy. `Mostly seen by age of 6 yrs Stippling present Interdental area Saddle shaped gingiva Papillary gingiva Gingival sulcus Newly erupted teeth sulcus depth is greater than deciduous predecessor 2-3mm References. Periodontics Revisited , Shalu Bhatla. Clinical Periodontics ,Carranza, 13 th edition.