Clinical Correlations of Periodontal Anatomy 2025 PDF

CLINICAL CORRELATIONS OF PERIODONTAL ANATOMY Dr. Mohamed Roshdy CONTENTS 1. ORAL MUCOSA and GINGIVA 2. PERIODONTAL LIGAMENT Review 3. CEMENTUM 4. ALVEOLAR PROCESS  CORELATIONS OF NORMAL CLINICAL AND MICROSCOPIC FEATURES ...

CLINICAL CORRELATIONS OF PERIODONTAL ANATOMY Dr. Mohamed Roshdy CONTENTS 1. ORAL MUCOSA and GINGIVA 2. PERIODONTAL LIGAMENT Review 3. CEMENTUM 4. ALVEOLAR PROCESS  CORELATIONS OF NORMAL CLINICAL AND MICROSCOPIC FEATURES ORAL MUCOSA 1. Masticatory mucosa: Gingiva and hard palate 2. Specialized mucosa: the dorsum of the tongue 3. Lining mucosa Gingiva Definition: It is that part of the oral mucosa that covers the alveolar processes of the jaws and surrounds the neck of the teeth in a collar like fashion. Anatomically: Marginal gingiva Attached gingiva Interdental gingiva Anatomical areas of gingiva AM DSCF0054 MGJ MG AG IDG GINGIVA  Marginal gingiva Marginal, free, or unattached gingiva Free gingival thickness:1.56 mm +/- 0.39 mm Collar Free gingival groove Soft tissue wall. Gingival Sulcus The gingival sulcus is the shallow crevice or space around the tooth bounded by the surface of the tooth on one side and the epithelium lining the free margin of the gingiva on the other side. V-shaped & barely permits the entry of periodontal probe. Depth: Ideal conditions: 0 mm or close to 0 mm Normal clinically healthy gingiva: 1.8 mm (histologic); Average: 1 to 3 mm. Attached gingiva Firm, resilient, tightly bound. Mucogingival junction Width of attached gingiva: Greatest: 3.5 - 4.5 mm in max. incisor 3.3 - 3.9 mm in man. incisor Least: 1.9 mm - maxilla 1.8 mm - mandible premolar region Thickness:1.25 mm +/- 0.42 mm  Interdental gingiva Occupies gingival embrasure. Pyramidal or Col shape, shape dependent on contact with adjacent tooth.  Microscopic features Gingiva is a combination of epithelial and connective tissue components. Epithelial component consists of: Oral epithelium Sulcular epithelium Junctional epithelium. Turn over rate: Palate, tongue & cheek: 5 to 6 days Gingiva: 10 to 12 days Junctional epithelium: 1 to 6 days Time taken by: Keratinized epithelium > Non keratinized epithelium Oral epithelium Primary barrier. Stratified squamous epithelium. Keratinized or parakeratinized.  Sulcular epithelium Thin, non-keratinized, stratified squamous epithelium. Without rete pegs Semipermeable Junctional epithelium Collar-like band. Stratified squamous non-keratinizing epithelium. Length: 0.25 to 1.25mm Widest in its coronal portion (about 15-20 cell layers), thinner (3-4 cells) towards the cemento-enamel junction.  Junctional epithelium is unique as it possess 2 basement membranes – the internal and external basal lamina Enamel Lamina propria Hemidesmosomes Internal Basal Lamina External Basal Lamina  Keratinization Keratinization consists of a series of biochemical and morphological events that occur in the cell as it migrates from the basal layer. Principle cell type : keratinocyte (90%) Other cell types (non-keratinocytes): Melanocytes, = (The ratio of melanocytes to the keratin producing epithelial cell is constant and is 1:36 cells, always in basal and spinous layers) Langerhans cells, = (APCs) Merkel cells, = (Tactile receptors of neural crest and epithelial origin and associated with nerve axons ) Inflammatory cells. Non-keratinization Lining mucosa is non-keratinized. Thicker than keratinized mucosa Cell size, intercellular bridges Thus, non-keratinized epithelium has 3 main layers: Stratum basale Stratum intermedium Stratum superficiale/distendum. Lamina propria Gingival connective tissue… 2 layers: Superficial: papillary Deep: reticular Components: Cells Blood vessels Neural elements Fibers Ground substance Gingival connective tissue Major portion consists of dense collagen fibers. Most common is type I, followed by type III. Classified according to their location and insertion Function of gingival fibers 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 The gingival fibers are arranged in three groups: gingivodental, circular, and transseptal. Gingival collagen fibers 1. Dentogingival fibers 2. Alveologingival fibers 3. Interpapillary fibers 4. Transgingival fibers 5. Circular and semicircular fibers 6. Dentoperiosteal fibers 7. Transseptal fibers 8. Periostogingival fibers 9. Intercircular fibers 10. Intergingival fibers Cell types (8% by volume) Fibroblasts-65% Neutrophils Lymphocytes Plasma cells Macrophages Mast cells Ground substance composed of glycosaminoglycans (most common dermatan sulfate- 60% followed by chondroitin -4-sulfate- 28%).  Vascular supply 3 main sources Supraperiosteal arterioles Vessels of the PDL Arterioles emerging from the crest of alveolar septa Juxta-epithelial plexus: The capillary plexus present adjacent to the papillary projections of the gingival epithelium. CORELATIONS OF NORMAL CLINICAL AND MICROSCOPIC FEATURES  Color Produced by the vascular supply, thickness & degree of keratinization of the epithelium, and presence of pigment containing cells. Varies among different persons…. Appears to be correlated with cutaneous pigmentation. Lighter in blond individuals with fair complexion than swarthy, dark-haired individuals.  Size Corresponds with the sum total of bulk of cellular & intercellular elements & their vascular supply. Alteration in size….common feature of gingival disease GINGIVAL BIOTYPES Ochsenbein and Miller have discussed the importance of “thick vs. thin” gingiva in restorative treatment planning. The distribution of the biotypes among population: Thick & flat periodontal biotypes: 85 % Thin & scalloped periodontal biotypes: 15 % -Olsson M, Lindhe J, 1991. THICK GINGIVAL BIOTYPE THIN GINGIVAL BIOTYPE Gingival Zenith The gingival zenith (GZ) is defined as the most apical point of the marginal gingival scallop. Examples: Central incisor: distal third Lateral incisor: central Cuspid: distal third Bicuspid: central  Surface Texture Gingiva presents a a textured surface similar to an orange peel & is referred to as being stippled. The attached gingiva is stippled; the marginal gingiva is not. Less prominent on lingual than facial surfaces & may be absent in some persons.  Stippling of attached gingiva Orange peel appearance. Best viewed by drying the gingiva May vary with age and sex (fine or coarse) Restricted to attached gingiva and central portion of the interdental papilla.  Passive eruption: Gottlieb & Orban in 1933 Stage 1: junctional epi & base of the sulcus..both on enamel. Stage 2: part of JE on cementum, base of sulcus still on enamel. Stage 3: entire JE is on cementum, base of sulcus at CEJ. Stage 4: both the JE & base of sulcus on cementum.  Connective tissue grafts Gingiva is considered to have a more stable relationship with the gingival margin of a restoration than alveolar mucosa. If gingival tissue is deficient, gingival grafts may be used to create new gingiva. Connective tissue-epithelial interactions?  Periodontal probing Periodontal probing does not accurately estimate the actual anatomic sulcus or pocket depth. Probing depth generally overestimates anatomic sulcus or pocket depth because the probe actually penetrates inflamed tissues.  Gingival crevicular fluid The gingival sulcus contains fluid (inflammatory exudate) derived from serum, structural cells of periodontium, plasma proteins, electrolytes, inflammatory and immune cells. It seeps into it from the gingival connective tissue through a thin sulcular wall of the crevicular and junctional epithelium. It is increased in presence of inflammation. The gingival fluid plays a protective role through: Cleansing action, Antibacterial action and Adhesive property. Transudate or Exuadate  Interdental COL The interdental "col” is not a powerful barrier against bacteria because it is covered by non-keratinized epithelium. = site of initiation of disease Key Points Gingiva is part of the Masticatory mucosa Gingiva = MG + AG + IDP (anatomically) MG + IDP = Free Gingiva FG + AG = KG (Keratinized Gingiva) Mucogingival Line (Junction) = MGJ Gingival Sulcus = 1-3 mm Gingiva = OE + SE + JE (microscopically) Key Points JUNCTIONAL EPITHELIUM (a unique structure) JE turnover rate = 1 to 6 days Principle cell type = keratinocyte (Epithelium) Principle cell type = Fibroblasts (CT) Most common collagen fibers is type I Transseptal fibers CLINICAL CORRELATIONS Periodontal Ligament PERIODONTAL LIGAMENT The periodontal ligament is composed of a complex vascular and highly cellular connective tissue that surrounds the tooth root and connects it to the inner wall of the alveolar bone. Average width of PDL space: 0.2mm Diminished around non-functional teeth, widened around teeth in hyperfunction Periodontal ligament fibers Principle fibers Collagenous, arranged in bundles and form a wavy pattern. Sharpey’s fibers Terminal portion of principle fibers that are inserted into cementum and bone. They undergo calcification Associated with abundant non- collagenous protein (osteopontin and bone sialoprotein) Oxytalan & eluanin fibers Principle fibers Transseptal Alveolar crest Horizontal Oblique Apical Interradicular  Cellular elements of PDL Connective tissue cells (Fibroblasts – Cementoblasts – Osteoblasts) Undifferentiated mesenchymal cells (UMC) Epithelial rests of Malassez Immune system cells Cells associated with neurovascular elements Ground substance of PDL Glycosaminoglycans (GAGs): hyaluronic acid, proteoglycans Glycoproteins: fibronectin and laminin. High water content (70%) Calicified structures : cementicles which may be free or attached to the root surface Functions of PDL Physical PDL Formative Nutritional and and sensory remodeling  Periodontal ligament clinical considerations 1. The periodontal ligament varies appears radiolucent in PA radiographs. 2. The ligament is thicker in functioning than non-functioning teeth. 3. The ligament cells are capable of remodeling the ligament & bone. 4. Accidentally exfoliated teeth can be replanted. 5. The periodontal ligament is unique among the periodontal tissues, in that it contains precursor cells (undifferentiated mesenchymal cells) for the production of the entire attachment apparatus of the tooth, i.e. cementum, periodontal ligament & bone. Cementum  Cementum is a specialized, calcified tissue of mesodermal origin covering anatomic root of human tooth. CC It Begins at cervical portion of the tooth at the CEJ and continuous AC to the apex. D It furnishes a medium for attachment of the fibers that bind the P tooth to the surrounding structure. STRUCTUE OF CEMENTUM E AELLULAR CEMENTUM = Primary cementum CELLULAR CEMENTUM = Secondary cementum  CEMENTUM CHARACTERISTICS Physical Characters: Cementum is less harder than dentin. Cementum is light yellowish in color and lighter than dentin. It can be distinguished from enamel by its lack of luster and darker hue. Under some experimental conditions cementum has been shown to be permeable to a variety of materials. Chemical composition The inorganic portion (45-50%) consists mainly of calcium and phosphate in the form if hydroxapatite. Cementum has highest fluoride content of all the mineralized tissues. The organic portion (50-55%) of cementum consists primarily of type 1 collagen, protein polysaccharides(proteoglycans) and water. SCHROEDERS CLASSIFICATION Acellular afibrillar cementum Acellular extrinsic fiber cementum Cellular mixed stratified cementum Cellular intrinsic fiber cementum Intermediate cementum is a poorly defined zone near the cementodentinal junction of certain teeth that appears to contain cellular remnants of the Hertwig sheath embedded in calcified ground substance  ACELLULAR CEMENTUM CC The term acelllular cementum is unfortunate. As a living tissue, cells are an integral part of cementum at all times. AC However, some layers of cementum do not incorporate cells, the spiderlilke cementocytes. Acellular cementum covers the root dentin from CEJ to the apex but often missing on apical third of root. Cementum is thinnest at the CEJ (20-50μm) Cementum is thickest towards root apex.(150-200μm)  CELLULAR CEMENTUM Fibers of Mostly presents at the apical third of root. Cells PDL included in cellular cementum are cementocytes, similar to osteocytes. Cellular They lie in spaces designated as lacunae. cementum Cell body has shape of plum stone, with numerous Canaliculi of long processes known as canaliculli. Most of the cementocytes processes are directed towards the periodontal surface of the cementum. Lacuna of cementocytes Both cellular and acellular cementum are separated by incremental lines into layers, which indicate periodic formation.  CEMENTOENAMEL JUNCTION 60-65% - cementum overlaps the cervical end of enamel for a short distance. 30% - meet at sharp line (Butt Joint) 5-10% - no CEJ but a zone of root devoid of cementum & covered by enamel epi.  Cementum clinical considerations 1. Cementum is essential for normal anchorage of the tooth. 2. It is more resistant to resorption than bone and it is for this reason that orthodontic tooth movement is possible, this protects the tooth itself. 3. Scaling and root planing, aimed at removing calculus and bacterial deposits, also readily removes the relatively thin cementum layer. Loss of cementum in such cases will expose dentin which in turn leads to sensitivity. 4. Cemental deposition in the apical portion compensates for occlusal attrition. 5. Cementicles 6. No CEJ in 10 % of teeth which in turn leads to sensitivity. Alveolar Process  ALVEOLAR PROCESS The alveolar process is the portion of the maxilla and mandible that forms and supports the tooth sockets (alveoli). It forms when the tooth erupts to provide the osseous attachment to the forming periodontal ligament; it disappears gradually after the tooth is lost. The alveolar process consists of the following: An external plate of cortical bone is formed by Haversian bone and compacted bone lamellae. The inner socket wall of thin, compact bone called the alveolar bone proper is seen as the lamina dura in radiographs.  Histologically, it contains a series of openings (i.e., the cribriform plate) through which neurovascular bundles link the periodontal ligament with the central component of the alveolar bone: the cancellous bone. Note: Remodeling is the major pathway of bony changes in shape, resistance to forces, repair of wounds, and calcium and phosphate homeostasis in the body. Indeed, the coupling of bone resorption with bone formation constitutes one of the fundamental principles by which bone is necessarily remodeled throughout its life. Bundle bone is the term given to bone adjacent to the periodontal ligament that contains a great number of Sharpey’s fibers. Note: Layers of differentiated osteogenic connective tissue cover all of the bone surfaces. The tissue that covers the outer surface of bone is termed periosteum, whereas the tissue that lines the internal bone cavities is called endosteum. Distance between the crest of the alveolar bone and the cemento-enamel junction in young adults varies between 0.75 and 1.49 mm (average, 1.08 mm). This distance increases with age to an average of 2.81 mm. Radiographically Osseous topography Normal architecture Variations Labioversion/ lingiversion  Isolated areas in which the root is denuded of bone and the root surface is covered only by periosteum and overlying gingiva are termed fenestrations. In these areas, the marginal bone is intact. When the denuded areas extend through the marginal bone, the defect is called a dehiscence.  Alveolar bone clinical considerations 1. Through remodeling, the alveolar bone may become displaced. 2. Interruptions in the continuity of the lamina dura in the apical region are of diagnostic significance. 3. Following tooth extraction, the alveolar process tends to resorb. 4. Placement of dental implants in the alveolar process, prior to it becoming resorbed, following tooth extractions, will markedly decrease the rate of ridge resorption. 5. Fenestrations may convert to dehiscences which, in turn, may lead to gingival recession. Key Points Average width of PDL space: 0.2mm Undifferentiated mesenchymal cells (UMC) Functions of PDL Cemento-Enamel Junction (CEJ) Alveolar Bone terminology CLINICAL CORRELATIONS Homework Draw the periodontium  Reference Textbook Chapter 3 Pages 19 - 49 Thank You