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Tour of the Periodontium Jafar Naghshbandi D.D.S;M.S Diplomate of the American Board of Periodontology  INTRODUCTION The term periodontium arises from greek words “peri” meaning around and “odont” meaning tooth. PERIODONTIUM: Tissues that invest and support the teet...

Tour of the Periodontium Jafar Naghshbandi D.D.S;M.S Diplomate of the American Board of Periodontology  INTRODUCTION The term periodontium arises from greek words “peri” meaning around and “odont” meaning tooth. PERIODONTIUM: Tissues that invest and support the teeth.  Periodontium Gingiva NORMAL PER Periodontal ligament İODONT İU (PERIODONTAL. LIGAMENT M ) Internal cortical plate: Boundle bone Root cementum External cortical plate Periodontium supporting structures The periodontium is composed of the supporting structures of teeth, namely: 1. Gingiva 2. Periodontal ligament 3. Cementum 4. Alveolar bone  Gingiva Gingival margin – the visible edge of the gingiva Gingival sulcus – (or crevice) which in health is between 0.5 and 3mm in depth Free gingiva – a mobile cuff of gingiva lying above the alveolar crest Attached gingiva – a band of 1–9mm in length, which is bound down to the underlying alveolus and cementum, by collagen fibres of the dentogingival complex. Gingival groove - The line at which the free gingiva becomes attached gingiva  GINGIVA Part of oral mucosa that covers the alveolar processes of the jaws and surrounds the necks of the teeth. Marginal gingiva A. Gingival Sulcus B. Interdental Gingiva  Marginal Gingiva Terminal edge of the Gingiva surrounding the teeth in collar like fashion. 1.5-2mm wide Channel Way Gingival Sulcus V-Shaped shallow Crevice 1.8mm Presence of crevicular fluid  Interdental gingiva Occupy gingival embrasure Site of initial lesion on gingivitis Anterior region-Pyramidal form and flattened over Molar region Scalloped Form Presence of Interdental COL  Attached Gingiva Functional Mucosa Firm, resilient and tightly bound to alveolar Bone Pale, pink and Stippled appearance Stippling Appearance  Periodontal ligament “The is the connective tissue that surrounds the root & connects it to the bone. It is continuous with the connective tissue of the gingiva & communicates with the marrow spaces through vascular channels in the bone.” Carranza & Bernard  Periodontal ligament Periodontal Ligament Surrounds the root of the tooth Composed of fibers, or ligaments, that support and suspend the tooth in the socket Fibers are arranged in bundles Forms a ‘shock-absorber’ for the tooth in the socket  Periodontal fiber groups Alveolar crest fibers-extend from cervical area of tooth to alveolar crest: Horizontal group – run at right angles Oblique group – slants into alveolar bone Apical group – extend from apex Interradicular –only in multi-rooted TeethTransseptal – from one tooth to another  Periodontal fiber groups Most important fibers: Oblique – largest group – resist vertical (up and down) force Work like shock absorbers Transseptal or interdental – support interdental gingiva  Gingival fiber group Found above the alveolar bone crest and below the epithelium Dentogingival fibers Circular ligament fibers Alveologingival fibers Dentoperiosteal fibers  Periodontal ligament Clinical considerations The PDL is an absolute requirement for rapid remodeling of alveolar bone when forces are applied to teeth. Cell of the periodontal ligament are Pluri-potent and helps in the regeneration of all the components of Periodontium lost in the periodontal disease process. Chronic periodontal disease causes the fiber groups to become disorganized and lose attachment due to resorption Occlusal trauma does not cause periodontal disease but can accelerate an existing condition  Periodontal ligament EXTENT In the coronal direction it is continuous with lamina propria of gingiva & is demarcated by the alveolar crest fibers. At the root apex it merges with the dental pulp. It ranges in width from 0.15- 0.38mm  Periodontal ligament SHAPE It is thinnest around the middle third of the root, with an hour glass appearance. The ligament appears as a radiolucent area of 0.4- 1.5mm between the radiopaque lamina dura of the alveolar bone and cementum Orbans  Periodontal ligament AVERAGE WIDTH: Depending on age: 11-16 yrs - 0.21mm 32-52 yrs - 0.18mm 51-67 yrs - 0.15mm According to functional state of the tissues Time of eruption - 0.1- 0.5mm At function - 0.2-0.35mm Hypo function - 0.1-0.15mm  Cementum Definition: It is a mineralized dental tissue covering the anatomic roots of human teeth It was first demonstrated microscopically in 1835by pupils of Purkinje The word cementum comes from the latin word “cement” which means quarried stone  Cementum PHYSICAL CHARACTERISTICS Calcified structure whose calcification and hardness is less than dentin More permeable than dentin Light yellow in color Softer and lighter than dentin Lacks luster and is dark, and is therefore differentiated from enamel  Cementum Less readily resorbed than bone EXTENSION: Begins at the cervical portion of the tooth at the CEJ and continues to the apex T HICKNESS: At CEJ : 10 microns ( thinnest ) At Apical Region : 200-300 microns ( thickest )  Cementum EXTENSION: Begins at the cervical portion of the tooth at the CEJ and continues to the apex THICKNESS: At CEJ : 10 microns ( thinnest ) At Apical Region : 200-300 microns ( thickest )  Cementum Classification of cementum Based upon: A. Location B. Presence or absence of cells C. Origin of collagenous fibers of the matrix According to Schoreder Classification of cementum Based upon Location: A) Radicular cementum Cementum that is found on the root surface. B) Coronal cementum Cementum that forms on the enamel covering the crown  Cementum B) Presence or absence of cells I. Cellular II. Acellular Cementum  Cemento-Enamel Junction Cementum overlaps enamel – 60% Cementum just meets enamel – 30% Small gap between cementum and enamel – 10% FUNCTIONS OF CEMENTUM 1. Medium for the attachment of periodontal ligament fibers to the tooth 2. Tooth wear compensation 3. Repair :fracture or resorption of root surface 4. Does not show resorption under masticatory or orthodontic forces as it is harder than bone. During heavy orthodontic forces, tooth integrity is maintained and alveolar bone being elastic in nature changes its shape, fulfilling the orthodontic requirement  Injuries to Cementum VERTICAL FRACTURE Poor prognosis and usually it cannot be repaired by cementum easily Treatment :extraction or stabilization by intracoronal splinting HORIZONTAL FRACTURE prognosis depends on the age and location of fracture. Apical or middle third: it can be repaired by the cementum and prognosis for the vitality of the pulp of the tooth for survival is fair The coronal third: prognosis for vitality of tooth is poor  Cementum Repair ANATOMIC REPAIR Generally occurs when the degree of destruction is low The root outline is re- established as it was before cemental resorption FUNCTIONAL REPAIR Occurs in cases of large cemental resorption or destruction To maintain the width of periodontal ligament, the adjacent alveolar bone grows and takes the shape of defect following the root surface. This is done to improve the function of tooth  Alveolar Bone Also called as alveolar process Definition: alveolar process is that part of maxilla and mandible that forms and supports the sockets of teeth It is composed mainly of two parts: Alveolar bone proper Supporting bone When the teeth are lost the alveolar process disappears Alveolar Bone  Structure of alveolar bone A) Alveolar bone proper lamellated bone bundle bone B) Supporting alveolar bone Cortical plate Spongy bone  ALVEOLAR BONE PROPER It surrounds the root of the tooth and gives attachment to the periodontal ligament fibers. It consists of: Lamellated bone Bundle bone  BUNDLE BONE Part of the alveolar bone where periodontal ligament fibres are inserted (attached) Bundle bone present at inner wall of alveolar socket Bundle – bundles of fibers Sharpeys fibers – principal fibres of the periodontal ligament that are embedded in the bone or cementum. Sharpeys fibers are seen perpendicular to the bundle bone. Other fibrils are less and are arranged parallel to the bundle bone surface  Lamina dura The alveolar process contains a region of compact bone adjacent to the periodontal ligament called Lamina dura. It is the bone lining the alveolus which is attached to the cementum of the roots by the periodontal ligament In clinical radiographs, it normally appears as a dense white line  Alveolar Socket Also called Dental alveolus Sockets in the jaws in which the roots of teeth are held in the alveolar process with the periodontal ligament Alveolar socket of the second premolar tooth in a bovine maxillary bone.  Septa “Septa” – in Latin, it means “fence” or “wall” Interdental Septa Are plates of bone that separate each individual sockets from one another Interradicular Septa Are thin plates of bone that separate the roots of multi-rooted teeth  Summary The normal periodontium is a unique and complex dynamic structure providing support necessary to maintain teeth in function Proper functioning of the periodontium is achieved through structural integrity and interaction between the various components tissues periodontium.