Periodontology: Normal Anatomic Considerations PDF

 periodontology Periodontology is the study of periodontium a specialized system of hard and soft tissue that supports the teeth and maintains its position. provides the support necessary to maintain teeth in function  The normal periodontium supporting appar...

 periodontology Periodontology is the study of periodontium a specialized system of hard and soft tissue that supports the teeth and maintains its position. provides the support necessary to maintain teeth in function  The normal periodontium supporting apparatus of the teeth, which attaches the tooth to the bone provides the support necessary to maintain teeth in function gingiva  The gingiva covers the alveolar bone and tooth root to a level just coronal to the CEJ protects the underlying tissues of the periodontium (bone & periodontal ligament) from the oral environment. Oral mucosa  Oral mucosa masticatory mucosathe covering of the hard palate andgingiva(The gingiva is the part of the oral mucosathat covers the alveolar processes of the jaws and surrounds the necks of the teeth.) specialized mucosa covered The dorsum of the tongue, lining mucoas:Loosely attached to their underlying structures and covered with non-keratinized epithelium. Lips, cheeks, floor of the mouth.  The gingival defense (protection)mechanisms include: Cell turnover and surface shedding (desquamation). Anatomical epithelial seal. The gingival fluid, it contains several defensive components  gingiva Macroscopic anatomy  Free gingiva Interdental gingiva Attached gingiva Free (marginal) gingiva  The marginal or unattached gingiva is the terminal edge or border of the gingiva that surrounds the teeth neck in collar like fashion. It is 1-3 mm wide It is demarcated from the adjacent attached gingiva by a shallow linear depression called the free gingival groove free gingival groove  The most apical point of the marginal gingival scallop is called the gingival zenith Gingival Sulcus  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. It is V-shaped, and it barely permits the entrance of a periodontal probe. The so-called probing depth of a clinically normal gingival sulcus in humans is 0-3mm Interdental gingiva  Interdental gingiva occupies the gingival embrasure, which is the interproximal space beneath the area of tooth contact. can be pyramidal, or it can have a “tent” shape. In the former, the tip of one papilla is located immediately beneath the contact point; anterior pyramidal posterior tent The shape of the interdental papilla is determined by: 1- The contact relationships between the teeth 2- The width of the proximal tooth surfaces 3- Course of the cemento-enamel junction. in anterior teeth, the interdental papilla is pyramidal form while in the molar region; the papillae are flattened in buccolingual direction (tent shape). Col region. Interdental col presents a Valleylike depression In teeth with contact surface the interdental papilla has a Col region. Interdental col presents a Valleylike depression that connects a facial and lingual papilla and that conforms to the shape of the interproximal contact.. If there is diastema, the interdental gingiva is flat or rounded without Col region.  If there is diastema, the interdental gingiva is flat or rounded without Col region  The Col region is covered by a thin nonkeratinized epithelium. The interdental region is of special importance (give reason)?  It is the site of the most persistent bacterial stagnation.  It is the site of initial lesion in gingivitis.  Moreover, the Col is covered by non-keratinized epithelium which is not a powerful barrier against bacterial insult. Attached gingiva  Attached gingiva continuous with the marginal gingiva. It is firm, resilient, and tightly bound to the underlying periosteum of alveolar bone. extends to the relatively loose and movable alveolar mucosa; it is demarcated by the mucogingival junction  The surface of the attached gingiva is stippled like orange peel It is generally greatest (width) in the incisor region (i.e., 3.5 to 4.5 mm in the maxilla, 3.3 to 3.9 mm in the mandible) and narrower in the posterior segments (i.e., 1.9 mm in the maxilla and 1.8 mm in the mandible). anterior maxilla > anterior mandible > posterior maxilla > posterior mandible The alveolar mucosa The alveolar mucosa separated from the periosteum by a loose, highly vascular connective tissue. Thus the alveolar mucosa is relatively loose and mobile tissue, deep red, in marked contrast to the pale pink attached gingiva. deep red alveolar mucosa Clinical criteria of normal gingiva:  Clinical criteria of normal gingiva: Color: pale pink Form: knife-edged fashion. Contour: festooned appearance.(following CEJ) Consistency: firm, resilient and tightly bound to the underlying hard tissues. Gingival sulcus: the probing depth of the healthy gingival sulcus may vary from 0 to 3 mm. Probing with a blunt probe should not cause bleeding. Pink, knife edged, festooned, firm, resilient and not bleeding with probing. Clinical criteria of inflamed gingiva: Color: reddish Form: blunt-edged fashion. Contour: loss of festooned appearance. Consistency: edematous, soft spongy and friable Microscopic Features STRATIFIED SQUAMOUS EPITHELIUM GINGIVA CENTRAL CORE OF CONNECTIV E TISSUE GINGIVAL EPITHELIUM ORAL (OUTER EPITHELIUM) SULCULAR EPITHELIUM JUNCTIONAL EPTHELIUM  ORAL (OUTER EPITHELIUM) Extent:is keratinized and extends from the mucogingival junction to the gingival margin Have rete pegs Turn over: 10-12 days THICKNESS outer epithelium 0.2-0.3mm KERATINIZATION keratinized or parakeratinized  Main function  PROLIFERATION DIFFERENTATION: involves the process of keratinization, which consists of progressions of biochemical and morphologic events that occur in the cell as they migrate from the basal layer to keratinous layer. LAYERS OF ORAL EPITHELIUM Cornifie or keratinous layer Irrigular polyhyral or polygonal cells  The epithelium is joined to the underlying connective tissue by a basal lamina. That consists of lamina lucida (mainly composed of the glycoprotein lamina densa.(composed of type IV collagen.)  Hemidesmosomes of the basal epithelial cells abut the lamina Lucida. Connecting filaments Non keratinocyte  Dendritic cells  Basal & spinous layers  Premelanosomes/melan osomes TYROSINAS E DIHYDROXYPHENYLALANINE TYROSINE (DOPA) MELANOPHORES MELANIN /MELANOPHAGES Racial pigmintation  Dendritic cells  Modified monocytes  Suprabasal layer  Antigen presenting cell for lymphocyte  Found: Oral epithelium & sulcular epithelium  Absent: Junctional epithelium  Deeper layer  Harbor nerve endings  Tactile perceptors  Lines gingival sulcus  STRUCTURE- Thin non-keratinized stratified squamous epithelium without rete pegs  EXTENT- Coronal limit of junctional epithelium to crest of gingival margin  SEMIPERMEABLE MEMBRANE 1/21/2025 INJURIOUS BACTERIAL PRODUCTS TISSUE FLUID FROM GINGIVA (GCF) COLLARLIKE BAND OF STRATIFIED SQUAMOUS NON KERATINIZING EPITHELIUM Which is located at the CEJ in healthy tissue 1/21/2025  CORONALLY- 10 -30 cells thick APICALLY- 1-2 cells LENGTH- 0.25-1.35mm TURNOVER 1-6 days Numerous migrating PMN’s Larger intercellular spaces 1/21/2025 Gingival crevicular fluid  Gingival crevicular fluid Gingival crevicular fluid (GCF) is a physiological fluid ( transudate in normal conditions) as well as an inflammatory exudate (in inflamation) originating from the gingival plexus of blood vessels in the gingival corium, subjacent to the epithelium lining of the dentogingival space. Lysosomes contain Desq. Epith. Cells carbohydrates K, Na, Ca, Ph and proteins hydrolytic enzymes Leukocyte M.O (Ab,complement)  Wash out irritant & prevent bacterial pentration Contain plasma protein to Lubrication of improve FUNCTIONS OF foreign material epithelial adhesion to the GCF facilitate its tooth expulsion Antibacterial enzymes +antibodies against bacteria 1/21/2025  B.V , nerve & lymphatic Ground substance The major components of the gingival connective tissue are collagen fibers (about 60% by volume), fibroblasts (5%), vessels, nerves, and matrix (about 35%) 1/21/2025  EPITHELIAL ATTACHMENT APPARATUS The attachment of the junctional epithelium to the tooth is reinforced by the gingival fibers, which brace the marginal gingiva against the tooth surface. For this reason, the junctional epithelium and the gingival fibers are considered together as a functional unit referred to as the dentogingival unit. 1/21/2025 gingival fibers connective tissue of marginal gingiva is densely collagenous containing a prominent system of collagen fibre bundle CONSIST MAINLY OF TYPE 1 COLLAGEN Reticulin Elastic fibers Oxytalen fibers 1/21/2025 FUNCTIONS OF GINGIVAL FIBRES  Dentogingival fibers EXTENT Facial, lingual & interproximal surfaces Originate at cementum Fanlike conformation Interproximally : Extend towards crest of the interdental gingiva FUNCTION: Provide gingival support EXTENT Arise in cementum INSERTION Crest of alveolar process Lateral aspect of cortical plate FUNCTION Anchor tooth to bone Protect PDL EXTENT: Running within Marginal & Interdental gingival CT Encircle each tooth Cuff /Ring like fashion FUNCTION Maintain contour & position of free marginal gingiva Biologic width 1/21/2025  The ground substance fills the space between fibers and cells; It is composed of glycoproteins (mainly fibronectin). is a protein-polysaccharide molecule in which protein component is predominating. Function help attachment and migration of fibroblasts. proteoglycans : it is a protein polysaccharide molecule in which polysaccharide component is predominating. Example for polysaccharide component is glucosaminoglycans (GAG). Function: 1- GAG can bind large amounts of water providing the characteristic resiliency of the gingiva (i.e. resist compressive force). 2- GAGs also facilitate transport of: nutrients, metablic products, cells and cytokines which are chemical massengers that modulate cellular function. Cells FIBROBLAST  Predominant connective tissue cells(65%)  Spindle or stellate shaped with oval nucleus containing one or more nucleoli  Function- maintains structural integrity of connective tissue by secreting extracellular matrix. And collagen fibers play a role in collagen turn over  MAST CELLS is responsible for the production of vasoactive substances, which can affect the function of the micro-vascular system and control the blood flow through the tissue. The cytoplasm is characterized by the presence of a large number of vesicles that contain the vasoactive substances such as histamin, heparin and proteolytic enzymes.  MACROPHAGES  phagocytic and synthetic functions.  Numerous vesicles (lysosome) are present in the cytoplasm which contains lysosomal enzymes.  Remnant of phagocytosed material that is present in phagosomes.  Derived from circulating blood monocytes which migrate into the tissue.  Macrophages are numerous in inflammed tissues. 1/21/2025  contain eccentrically Neutrophils also located spherical called polymorphonuclear are nucleus. They are characterized leukocytes. The nucleus is lobulated and there are responsible for the by an oval numerous lysosomes in production of different nucleus. They the cytoplasm that contain types of mediate lysosomal enzyme. immunoglobulins. humoral and cellular immune response. Gingival blood, lymph and nerve supply: 1-Supraperiosteal vessels 2- Periodontal ligament vessels 3- Alveolar vessels that emerge from alveolar crest. Lymphatic drainage Lymphatic drainage starts in connective tissue papillae and drains into regional lymph nodes. from mandibular gingiva into the submandibular and sub mental lymph nodes. from the maxillary gingiva into the deep cervical lymph nodes The nerve supply is derived from branches of: The trigeminal nerve. A number of nerve endings have been identified in the gingival connective tissue as tactile corpuscles and (temperature , pain) receptors. Periodontal ligament The periodontal ligament is the connective tissue (complex vascular highly cellular)that surrounds the root and connects it with the bone. It is continuous with the connective tissue of the gingiva and communicates with the marrow spaces through vascular channels in the bone. the average width is about 0.2 mm The fibers of the periodontal ligament are type I & III mainly collagen. principle fibers are type I They are divided into: A) The principal fibers. (The most important components of PL are the principle fibers which are collagenous and arranged in bundles) B) The accessory fibers. C) The oxytalan ( elastic ) fibers.  Principle fibers 1-Alveolar crest group: It prevent the extrusion of the tooth and resist lateral tooth movements. 2-Horizontal group: The fiber bundles run from the cementum to the bone at right angle to the long axis of the tooth. 3- Oblique group: The fiber bundles run obliquely. From bone going inserted apically to cementum It is the greatest number of fiber bundles found in this group. They perform the main support of the tooth against masticatory force. They bear the brunt of vertical masticatory stresses and transform them into tension on the alveolar bone. 4- Apical group: The bundles radiate from the apical region of the root to the surrounding bone. 5- Interradicular group: The bundles radiate from the interradicular septum to the furcation of the multirooted tooth.  Sharpey fibers The terminal portions of the principle fibers that are inserted into cementum and bone are termed sharpey fibers embeded in alveolar bone or tooth and calcify to a considerable degree  Accessory fibers: It is collagenous in nature run from bone to cementum in different planes, to prevent rotation of the tooth found in the region of the horizontal group.  Oxytalan fibers  Oxytalan fibers run parallel to the roots and bend to attach to cementum in cervical 1/3 it regulate vascular flow  Immature form of elastic fibers.  Run in axial or oblique direction.  One end being embedded in cementum or bone and the other end in the wall of b.v.  they play a part in supporting the blood vessels of the periodontal ligament during mastication i.e., it prevents the sudden closure of the blood vessels under masticatory forces. Function of periodontal ligament Soft tissue casing protecting B.V and nerve from injury of mech. Force Phsical transmission of occl. force to bone, Attachment of tooth to bone Resistance to the impact of occlusal force (shock absorption)  The periodontal ligament having the Sensory mechanoreceptor contributes to the sensation of touch and pressure on the teeth. proprioceptive receptors localization of pain The blood vessels in the periodontal ligament provide nutrient supply required by the cells Nutritive of the ligament and to the cementocytes and the most superficial osteocytes.  The fibroblasts for the formation of new periodontal ligament fibers and dissolution of the Formative: old fibers Cementoblasts and osteoblasts are essential in building up cementum and bone. a- The principal fibers: The arrangement of the fiber bundles in the different groups is well adapted to fulfill the functions of Protective the periodontal ligament. transforms the masticatory pressure exerted on the tooth into tension or traction on the cementum. and bone. Thickness of Periodontal Ligament Age, location of the tooth, and degree of stress to which the tooth was subjected It is widest at the coronal part of the socket and at the apex and narrowest at the level of the axis of rotation of the tooth which is about the middle of the root. The mesial side is thinner than distal side  A tooth that is not in function has a thin periodontal ligament  A tooth in functional occlusion has a periodontal ligament space of approximately 0.1 mm to 0.3 mm  A tooth subjected to abnormal stress has a considerably thicker periodontal space.  Histological structure The periodontal ligament is formed of : cells Extracellular substances Synthetic Fibers Resorptive ground substances Progenitor blood vessels,nerves Defensive & lymphatics. The cells Fibroblasts, osteoblasts & cementoblasts. are the most abundant cell type in the periodontal ligament because of the high turnover of collagen and proteoglycan with periodontal ligament. These cells are actually engaged in protein synthesis, they are also responsible for collagen degradation within the ligament.  cementoclasts , osteoclasts fibroclasts. N.B resorptive and synthetic cells responsible for Resorptive remodelling of the principle fibers to adapt to cells physiologic needs. which are derived from blood monocytes appear on bone surface during bone resorption. Progenitor Cells undifferentiated mesenchymal cells which Pluripotent cells are undifferentiated mesencymal cells (stem cell) that differentiate to osteoblast, fibroblast and cementoblast.  Defensive macrophage, lymphocytes and mast cells cells epithelial cells remnants of the Epith. Rest of epithelial root sheath of Hertwig appear isolated malassez cluster of cells or interlacing strand close to cementum May contain KGF (keratinocyte growth factor) Extracellular substances Proteoglycan and glycoprotein (fibronectine & laminin) ground substances Important for cell adhesion cell-cell adhesion , cell- matrix interaction. Cementum Definition: Cementum is a calcified avascular tissue that forms the outer covering of the anatomic tooth root.  Types of cementum -Primary (accelular) cementum -Secondary (cellular) cementum  Physical Characteristics 1-Color Light yellow Lighter in color than dentin 2- Thickness Acellular cementum (16-60µ) Cellular cementum (150-200 µ) 3- Permeability Permeable from dentin and PDL sides. Cellular C is more permeable than acellular C.  Acellular Cementum CELLULAR CEMENTUM First cementum formed and Formed after tooth reach the formed before tooth reach the occlusal plane. occlusal plane. Contain cells (cementocytes) Not contain cells in individual space (lacuna) Sharpey fibers make up most of that communicate with each its structure (from fibroblast) other through anastomosing Contain intrinsic collagen fibrils canaliculi (from cementoblasts) that are calcified that are irrigularily Less calcified than acellular arranged or parallel to the surface cementum Sharpey fiber occupy smaller portion Both type arranged in lamellae separated by incremental lines There are two sources of collagen fibers in cementum: - The extrinsic fibers (Sharpey’s fibers) which are the embedded portion of the principal fibers of the periodontal ligament and are synthesized by fibroblasts of the periodontal ligament. The intrinsic fibers which belong to the matrix of cementum forming irregular mesh work and they are synthesized by cementoblasts. Cementum resorption may occur as a consequence of faulty orthodontic movement or pressure from tumor. The greatest thickness of cementum is formed at the apex and in the furcation area. With attrition, a compensatory deposition of apical cementum takes place.  30% cementum 10% cementum and enamel 60% cementum meets the enamel overlaps E (afibrillar don’t meet because of in a sharp line cementum) (edge to edge) delayed separation of epith root sheath of Hertwig (area of dentin not covered by C). Alveolar process is the portion of maxilla and mandible that forms and supports the tooth sockets. It consists of, -External buccal and lingual cortical plate. -Inner socket wall of compact bone called Alveolar bone proper ,seen as lamina dura in radiographs. -Cancellous trabeculae between these two layers, which act as a supporting alveolar bone.  alveolar bone is formed of : ALVEOLAR BONE SUPPORTING ALVEOLAR PROPER BONE CORTICAL PLATE LAMELLATED BONE BUNDLE BONE Lamina dura SPONGY BONE IMP: lamina dura named as cribriform plate  Cribriform plate Vs Lamina dura ( socket wall) alveolar bone proper formed of (compact bone) dense lamellated bone lining of the tooth socket or alveoli (The space in the alveolar bone that accommodate the roots of the teeth (tooth socket). , is also called the cribriform plate because of the many holes through which Volkmann’s canals pass (from the alveolar bone into the PDL). Cribriform plate radiogrphically called lamina dura. Due to its dense radiopaque appearance Interproximal bone (interdental septum): bone located between the roots of adjacent teeth. - Interradicular bone: bone located between the roots of multirooted teeth. - Radicular bone: alveolar process located on the facial or lingual surfaces of the roots of teeth. b. supporting alveolar bone: Cancellous trabeculea between those component of compact layer of alveolar bone (interdental septum) Basal bone that part of jaw unrelated to teeth When teeth are displaced out of the arch (lateral inclination), the overlying alveolar plate may be very thin or even perforated so that fenestrations (circumscribed defects) Fenestration is window-like defect in the bone. 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  Periosteum and endosteum Periosteum“: cover all of the bone surfaces. The periosteum consists of an inner layer (osteogenic layer) composed of osteoblasts surrounded by osteoprogenitor cells, which have the potential to differentiate into osteoblasts, outer layer (fibrous layer) rich in blood vessels and nerves and composed of collagen fibers and fibroblasts.  endosteum whereas the tissue that lines the internal bone cavities composed of a single layer of osteoblasts and sometimes a small amount of connective tissue.. Alveolar bone is formed during fetal growth by intramembranous ossification, and it consists of a calcified matrix with osteocytes enclosed within spaces called lacunae. The osteocytes extend processes into canaliculi that radiate from the lacunae. The canaliculi form an anastomosing system through the intercellular matrix of the bone, which brings oxygen and nutrients to the osteocytes through the blood and removes metabolic waste products. Blood vessels branch extensively and travel through the periosteum. Haversian systems (i.e., osteons) are the internal mechanisms that bring a vascular supply to bones that are too thick to be supplied only by surface vessels. These are found primarily in the outer cortical plates and the alveolar bone proper.