Practice 3 Tonsils – Waldeyer's ring (Cut of decalcified tooth) Periodontium Gingiva Tonsils – Waldeyer's ring Group of peripheral lymphoid organs positioned at the entrance into naso- and oropharynx Total 6 (tonsillae palatinae, tonsillae tubariae, tonsilla lingualis, tonsilla pharyngea) Mucosal organs – accumulation of lymphoid tissue in lamina propria B - dependent areas - secondary lymph follicles T-dependent regions - interfollicular zones Palatine tonsils Positioned on the right and left side between glosopalatal and pharyngopalatal arches, ovoid shape, deep and branched tonsillar crypts, there are usually up to 35 (contain detritus), tonsil separated by fibrous capsula – can have septs. The surface of the tonsil is covered by a stratified squamous epithelium In lamina propria are large lymphatic follicles with light germinal centers Brighter center - contains centroblasts Epithelium above nodules (differences): The structure of the epithelium and the contacts between the cells are very loose, caused by infiltration by lymphocytes, macrophages, dendritic cells, discontinuous basement membrane FAE – (follicle associated epithelium) Palatine tonsils A B A B Tonsilla palatina (H.E.) 1 – stratified squamous epithelium 2 – lymphocytes infiltrated epithelium (FAE) 3 – secondary lymph nodules or follicles 4 – detritus in tonsilar crypt Tonsilar crypt in detail (H.E.) 1 – stratified squamous epithelium 2 – with lymphocytes infiltrated epithelium 3 – germinal centre of a secondary nodule 4 – detritus Lymphocytes which penetrate into the oral cavity are referred to as salivary bodiesPalatine tonsils Group of lymph nodules (folliculi linguales) in the mucosa of lamina propria on the dorsal side of radix linguae behind the circumvallate papillae Surface covered by stratified squamous epithelium At the bottom of shallow crypts are openings of purely mucinous Webers glands (gll. Linguales posteriores) Crypts are perpetually washed outs – no detritus. No obvious capsula. Lingual tonsil Lingual tonsil Located on the top of pharynx (fornix pharyngis) From the other it differs by the surface covered by pseudostratified columnar epithelium which might contain goblet cells Shallow crypts In childhood tonsilla pharyngea can often be hypertrophic which cause problems with nose breathing Paired tonsil Group of small lymphoid tissue in lamina propria of mucosa in the pharyngeal opening of the eustachian tube (ostium pharyngeum tubae auditivae) Pharyngeal tonsil (Adenoid) Tubal tonsils (Gerlach tonsils) Microscopic structure of periodontium, function and clinical relevance Consists of: • Alveolus • Periodontal ligament – dense collagenous tissue which ensure tooth stability and its attachment inside the alveolus • Cementum – covering roots • Gingiva Periodontium (in general meaning) gingiva cementum Periodontal ligament alveolus Hold teeth inside the alveolus – Balance and compensate the forces acting during mastication (thecodontn dentition) Transforms compressive forces during chewing into tensile, which the dental bed better resists and is also better adapted to Fills the space between the cribriform plate of dental socket and root (cementum) Dense collagenous tissue with higher amount of ECM (extracellular matrix) Periodontium thickness - 0.18 - 1.0 mm, the thinnest in the middle part of the root Collagenous fibers - fiber bundles - periodontal ligaments (ligaments) Ends anchored in dental cementum and lamellar bone of cribriform plate (as Sharpey fibers) They are of different thicknesses and have a wavy course Periodontal ligaments Development Cellular: Fibroblasts a Fibrocytes ECM: Collagen fibres (I, III a XII) Fast turnover Organized into bundles Elastic fibres Oxytalan fibres (immature elastic fibres) Microscopic structure Arrangement of periodontal ligaments 3 main groups: Gingival fibres Transseptal (interdental) fibres Alveolar fibres (fibrae principales) 4 directions (groups): Dentogingival – from cementum at the tooth neck to gingiva afixa and libera. Most abundant Alveologingival - from the edge of the alveolus gingiva afixa and libera Circular - placed in free gingiva and they surround the neck of the tooth Dentoperiostal - from the neck through the edge of the alveolus on the vestibular surface or lingual plate Gingival fibres – attach the gingiva to the neck of the tooth they are not actually part of the periodontium (they lie in the lamina propria of the gingiva) Dentogingival Dentoperiostal Mesiodistally above the interalveolar septa They strengthen the linear alignment of the teeth in the arch and form the basis for interdental papillae They form the shape of the ridges of theinteralveolar septum X-ray configuration (with inclination of septal tilt and depression) Transseptal fibres – connect necks of neighboring teeth Between root and cribriform plate of alveolus (os alveolare) Most abundant Alveolar fibres Alveolar crest group – from the neck to periosteum of interalveolar septum or periosteum of coronal edge of alveolus. Function: They prevent the tooth from moving out of the alveolus (sometimes missing) Horizontal group – in coronal third of tooth root and alveolus Perpendicular to the longitudinal axis of the tooth Function - Prevents lateral (horizontal) movements of the teeth Alveolar fibres Oblique group – in the middle and apical third of root/alveolus Diagonal course - the attachments on the cement positioned more apically than the insertion in the cribriform plate Function - Prevents the root from being pushed into the bed Apical – from the tooth apex to the bottom part of alveolus Radial course Function – Prevent the tooth from moving out of the alveolus (sometimes missing) Interradicular – only in teeth with more roots At the place of root branching Attached to the alveolar septum between roots Function – prevent the tooth from moving out of the alveolus and the rotation interradicular septum Interradicular septum Summarization Intermediate plexus Some fibres has only one attachment – either in cementum or in cribriform plate of alveolar bone and the other is free From this fibres is constituted Intermediate plexus Function: - Morphological and functional supply for potential reorganization of periodontal ligament - Support for interstitial areas Interstitial areas Regions of loose collagenous tissue Separate bundles of ligaments Space for blood vessels and nerves which are responsible for periodontal space vitality On samples they are paler tissue with obvious blood vessels and surrounded by amorphous tissue Highly innervated and numerous blood vessels in this region Arterioles derived from gingival, „pulpal“ and interalveolar branches In interstitial areas they form a dense capillary network which branches can be found also between the ligaments Lymphatic vessels Blood and nervous supply of periodontal space Innervation Three types of nerve endings • Free nerve endings (pain) – from unmyelinated or from myelinated nerve fibers) • Ruffini-like endings – In apical part of PDL • Lamellated corpuscles ERM (Epithelial rests of Malassez) • Epithelial remnants from disintegrated HERS (Hertwig Epithelial Root Sheat) • Pool of stem cells, interactive support for adjacent cells • Can undergo EMT (Epithelial to Mesenchymal Transition) Granulomas and cysts Cementicles Other structures in periodontal space ERM = Epithelial rests of Malassez Changes while losing an antagonist – nonfunction • Periodontal space narrowing • Weakening and loosening of fibers • Cementum thickening • Weakening of the cribriform disc Changes due to overload Acute (trauma) – blood effusions, fiber rupture, necrosis and resorption, ankylosis Chronical – hypercementosis Periodontal changes during ageing Periodontal fibres (ligaments) - terminology Gingival fibres - fibrae gingivales (fibrae gingivodentales, fibrae gingivales circulares) Transseptal fibres - fibrae interdentales Alveolar fibres - fibrae alveolodentales (fibrae principales) Alveolar cres - lig. dentale superius Horizontal - fibrae alveolodentales transversae Oblique - lig. dentale inferius Apical - fibrae apicales Interradicular - fibrae interradiculares Gingiva • Masticatory oral mucosa • Around tooth necks and covering alveolar bone. Firmly attached to adjacent hard tissues • Very stiff, pale pink color, resistant to pressure and friction • It is not movable – forming mucoperiosteum Mucogingival junction (line) • The border between gingiva and lining mucosa which covers the rest of alveolar process • Apparent on the vestibular aspect of both mandible and maxilla and on lingual aspect of mandible Gingiva Topography: 2 compartments Gingiva libera (Free gingiva) (gingiva supraalveolaris) Gingiva affixa (Attached gingiva) (gingiva alveolaris) Gingiva Sulcus gingivalis (Gingival sulcus) • Circular groove, physiological depth: 1-2 mm • Liquor gingivalis: plasma-like fluid which leaks from adjacent capillaries. The fluid has antimicrobial and anti-inflammatory properties, contains proteins and carbohydrates Interdental papillae, interdental gingiva Between neighbouring teeth, free gingiva forms a protrusion: trigonum interdentale Vestibular and lingual aspect Každá má vestibulární a linguální část, connected by intedental saddle Trigonum interdentale Stratified squamous epithelium Keratinized at vestibular and palatinal side No keratinization on the side facing teeth: Sulcular epithelium On the side facing teeth it keeps nondifferentiated epithelium characteristics. Junctional epithelium (epithelial attachment of Gottlieb) is firmly attached to teeth and seal the periodontal space from the environment of oral cavity. Microscopic structure of gingiva Gingiva affixa Dense collagenous connective tissue with papillas which are numerous and thin. Their presence causes a rough surface Gingiva libera Under the epithelium of free gingiva is lower amount of papillas and always missing under epithelium which is facing teeth Collagenous fibres are ordered into 4 groups: dentogingival, circular, dentoperiostal and alveologingival (chapter periodontium) Lamina propria Epithelial attachment, epithelial attachment of Gottlieb, Protects the periodontal space from aggresive outer environment of oral cavity resp. sulcus gingivalis (against bacteria, toxins, pieces of food) It is characteristic by the fusion of sulcular epithelium with hard tissues of teeth in the are of the neck Zone of fusion is under the sulcus gingivalis Width: 0,25 - 1 mm This epithelium is permanently actively regenerated – stem cell activity Cells are in several layers, flattened Junctional epithelium Between the innermost layer of cells and hard tissue are hemidesmosomes, between cells are desmosomes The line between epithelium and connective tissue is smooth (no papillae), connective tissue contains numerous leukocytes and B-lymphocytes, acts as an immunological barrier Narrowing ath the apical end Fast turnover: 4-6 days. Regenerates well after mechanical damage Junctional epithelium Consequence: tooth loosening and ultimately tooth loss Gingival recession in periodontitis Normal state: in primary dentition and healthy permanent dentition up to 20‘-30‘ – the apical end of the junctional epithelium at CEJ Later junctional epithelium moves more apically, until it finally moves to the cementum of the tooth neck In old age, cementum, can be exposed and a condition in which the clinical crown becomes larger than the anatomical crown Gingival recession Arterioles from aa. alveolares, a. mentalis, aa. palatinae, a. buccinatoria Branch into capillary networks with anastomosis with the periodontal network Lymphatic vessels and along the blood vessels Nerve fibres as a free nerve endings and form corpuscles Blood supply and innervation of gingiva