Anatomy of the Periodontium The tissues that surround and support the teeth are known as the periodontium. It includes: 1. Gingiva 2. Periodontal ligament 3. Alveolar bone 4. Cementum Periodontium: peri = around . odontous = tooth Periodontics: the art and science of studying the periodontium. Periodontist: specialist in periodontics

1) Gingiva

 Gingiva: The fibrous investing tissue covered by keratinized epithelium. The gingiva is one of the soft tissues that line the oral cavity. All the soft tissue in the mouth are Known as the the oral mucosa, it is divided into three different types:

Masticatory mucosa: Is a tissue that is firmly attached to the underlying bone and covered with parakeratinized or keratinized epithelium. The gingiva and the tissue covering the hard palate are examples. Lining mucosa: Loosely attached to their underlying structures and covered with non-keratinized epithelium. Lips, cheeks, floor of the mouth. Specialized mucosa: Covers the dorsal surface of the tongue.

Types of gingiva: Marginal gingiva (free or unattached) Attached gingiva (firmly attached to underlying tooth and bone) Inter-dental gingiva( located between adjacent teeth. Gingival sulcus

Clinical features Microscopic features

Clinical 1)Mucogingival junction. 2)Interdental gingiva. 3)Free gingival groove 4)Attached gingiva. 5)Alveolar mucosa 6) Marginal gingiva.

1:Enamel. 2:gingival margin. 3:gingival sulcus. 4:free gingival groove. 5:lveolar bone. 6:CEJ 7Cementum 8:PDL Between 2 and 4 is free gingiva

1) Is the most coronally positioned portion of the gingiva.  Marginal gingiva: 1) Is the most coronally positioned portion of the gingiva. 2) It is not attached to the tooth, and it creates the soft tissue wall of the gingival sulcus. 3) In health, is knife-edged in contour, firm in consistency, and smooth in texture. 4) It extends apically to the free gingival groove, approximately 1 mm wide.

1) It is firmly bound to the underlying tooth and alveolar bone. Attached Gingiva: 1) It is firmly bound to the underlying tooth and alveolar bone. 2) Gingiva is tapered in contour, stippled in texture, and firm in consistency. 3) Varies in width from one area of the mouth to another and from one patient to another. 4) Bound coronally by the free gingival groove and apically by the mucogingival junction.

Greatest in incisor region (3.5-4.5 in maxilla, 3.3-3.9 in mandible).  Attached Gingiva is: Greatest in incisor region (3.5-4.5 in maxilla, 3.3-3.9 in mandible). Least in premolar area (1.9 mm in maxilla, 1.8 in mandible). The width increases with age. Depends on teeth involved, the buccolingual position in the arch , location of the frenum or muscle attachment. It provides gingival tissue that can withstand the mechanical forces of brushing and tension applied on mucosa.

 Gingival sulcus: * It is a shallow fissure between marginal gingival and the enamel or cementum. * Clinical normal gingival sulcus depth = 2-3 mm measured with periodontal probe.

 Interdental gingiva: Its that part of the gingiva that occupy the inter-proximal space, created by adjacent teeth in contact. Therefore, shape determined by contact relationship with teeth, and width of proximal surfaces. If the contours are flat, interproximal contacts, the gingiva will be narrow and short. If the proximal contours are more convex with a small coronally positioned contact area, the interdental gingiva will be broad and high.

The interdental gingiva can be pyramidal and have col shape.  Buccolingual dimension the inter-dental gingival terminates coronally with separate buccal and lingual peaks of tissue as the gingival col.

Gingival Groove (4): It is a shallow, v-shaped or indentation that is closely associated with apical extent of free gingiva.

 The understanding of clinical features of periodontium is enhanced by a knowledge of histological component of tissue.

Microscopic (Histological) Features The gingiva consist of central core of connective tissue covered by stratified squamous epithelium.

1) Oral (outer) Epithelium. 2) Sulcular Epithelium  Gingival Epithelium: 1) Oral (outer) Epithelium. 2) Sulcular Epithelium 3) Junctional Epithelium

 Oral Epithelium: Keratinized or parakeratinized consist of four layers: 1) Stratum basale,Basal cell layer (The deepest cells) 2) Spinosum cell layer 3) Stratum granulosum cell layer 4) Stratum corneum(Keratinized, para, or nonkeratinized) cell layer

Layers of Squamous epithelium

Sulcular Epithelium: It lines the gingival sulcus facing the tooth similar to oral epithelium except the 2nd layer (it lacks granular cell layer) It acts as semipermeable membrane from the bacteria and tissue fluid from the gingiva seeps into the sulcus.

Junctional Epithelium: Forms the core of epithelium. It is thickest in coronal part. Is single or multiple layer of non-keratinized cells adhering to tooth surface and face the gingiva by means of basal lamina. Basal Lamina consist of: Lamina lucida Lamina densal

Details of the sulcular junctional epithelium areas

 Connective Tissue: Is known as the lamina propria. Divided into two layers: (1) the papillary layer adjacent to epithelium, (2) reticular layer, contiguous with the periosteum. Lamina propria consist of: Collagen fibers Intercellular ground substance Cells Blood vessels Nerves

Gingival collagen fiber. 1.circular fibers 2.dentogingival fibers. 3.alveologingival fibers. 4.periostogingival fibers.

Histological charecterstics of the gingiva(Faciolingual section of the periodontium)

The fibers are grouped: 1. Gingivodental 2. Circular 3. Transeptal  The collagen fibers help to hold the marginal gingiva tightly against the tooth and provide a firm junction of the attached gingiva to the underlying tooth root and alveolar bone. The fibers are grouped: 1. Gingivodental 2. Circular 3. Transeptal 4. Alveolo gingival 5. Inter-radicular fibers 6. Intra-papillary fibers

The most prominent cells found in the gingival connective tissue: 1. Plasma cells 2. Fibroblasts 3. Mast cells 4. Lymphocytes

Vascular Supply: It’s derived from the branches of the superior and inferior alveolar arteries: 1. Greater palatine artery 2. Buccal artery 3. Sublingual artery 4. Mental artery

 The lymphatic drainage usually follows the blood supply, the major portion of the lymph drainage from the gingiva going to the submandibular lymph nodes.

 Gingival Fluid: The gingival (crevicular) fluid is continually secreted from the gingival connective tissues into the sulcus through the sulcular epithelial wall. This fluid helps to mechanically clean the sulcus and in addition, possess anti-microbial properties and antibodies that enhance the resistance of the gingiva to gingivitis.

Clincal Relationship

Clinical Descriptive Criteria  Gingival color: Its pink depends on: - amount of melanin - thickness of epithelium - degree of keratinization - vascularity

 Gingival contour: The inter-dental gingiva is generally pointed. However, the contours of the gingiva vary depending upon the shape of the teeth, the buccolingual position of the teeth in the arch, and the size of the inter- proximal embrasure space.

 Gingival Consistency: Usually resilient and firm because of the dense collagenous nature of the gingival connective tissue.  Gingival Surface Texture: Being stippled like an orange peel or smooth and shiny. Degree of stippling varies considerably among patients and in different parts of the same mouth.

Nerve Supply:  Derived from maxillary and mandibular branches of the trigeminal nerve.

Periodontal Ligament

Periodontal ligament Connective tissue around and attach teeth to the alveolar bone. Consist of bundles of fibers, according to their directions: 1)Alveolar crest group 2)Horizontal group 3)Oblique group. 4)Apical fibers.

The ends of the princible fibers are embeded in cementum on the tooth side and in the alveolar bone proper on the opposite side. The embeded portions of the princible fibers are the Sharpey’s fibers

Functions Physical (mechanical) Formative Nutritional Sensory

The physical functions of pdl Transmission of occlusal forces to the bone. Attachment of the teeth to the bone. Maintainance of the gingival tissues in their relationship to the teeth. Resistence to the impact of occlusal forces(shock obsorption). Provision of a soft tissue casing(to protect vessels and nerves from injury by mechanical forces).

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Cementum

Cementum:  Calcified tissue covers the root of the teeth and provide attachment to the periodontal ligament.  Consist of collagen fibers in a ground substance consist of 45-50% inorganic materials. 50-55% organic materials

. Width vary from 60-68 microns in coronal  Width vary from 60-68 microns in coronal third 150-200 microns in apical third.  Width increase with age. 95 microns at age 20. 215 microns at age 60  Two types of cementum a cellular (coronal portion of the root) Cellular apical portion of root and in furcation areas of multi-rooted teeth.

Cemento Enamel Junction: The area where cementum and enamel meet (cervical area). Three different relationship: 60-50%  cementum overlaps enamel 30%  edge to edge 5%-10%  cementum fail to meet enamel resulting in exposed dentine

1:dentine.2:acellular cementum.3:pdl with fibroblast.4:cementoblast Cellular cementum. Cementocytes within the lacuna of cementum