Dental pulp Dentin Jan Krivanek 5. 4. 2023 (Krivanek et al., 2017) The fundamental importance of the pulp: a) Tooth vitality - nutrition and protection of odontoblasts against foreign and infectious agents b) Reparative processes - pool of undifferentiated cells for pulp fibroblasts and odontoblast-like cells Dental pulp shape depends on: - Tooth Type - Age of the individual - Pathological and repair changes Dentin-pulp complex Summary term used for dental pulp and dentin Tight developmental, histological and functional connections Common development history (ectomesenchymal origin) Dental pulp Fibroblasts Odontoblasts Stromal pulp tissue Support for odontoblasts Support for blood vessels and nerves Immune reactions Stem cell niche Dentin production Living component of dentin Reactions on tooth damage (pain, immune response, reparative processes) Interactions Dentin-pulp complex Odontoblasts Interface of dentin and the pulp Elongated shape, polarization (nucleus with organelles in basal third) Single cell layer Secretory vesicles on apical side Odontoblasts function - In healthy teeth, lifetime-active cells - Odontoblasts‘ processes/fibres (Tomes Fibres) maintain dentin matrix formation, responsible for dentin viability - Odontoblats‘ processes involved in the pain perception - Periodontoblastic space between the tubule wall and Tomes fibre, contains dentinal fluid and mucopolysaccharide material Odontoblasts Odontoblasts Odontoblasts / Pulp cells Development of odontoblasts Development of odontoblasts Enamel Dentin Microscopic structure of dental pulp, function and changes during aging Ectomesenchymal origin Located in cavitas dentis Reticular structure In primary dentition structure similar to jelly-like connective tissue Extracelular matrix (ECM) • Fibres: • Collagen • Reticular fibres • Amorphous matter: • Glycosaminoglycans and glycoproteins Cellular part • Particularly fibroblasts, • Immune system: macrophages, plasma cells, dendritic cells and tissue-residential blood cells (neutrophiles or eosinophiles, granulocytes, lymphocytes) • Glial cells • Endothelial cells, pericytes • Dental mesenchymal cells Stem Cells in (human) teeth Schematic of potential sources of adult stem cells in the oral environment TGPCs tooth germ progenitor cells DFSCs dental follicle stem cells SGSCs salivary gland stem cells SCAP stem cells of the apical papilla DPSCs dental pulp stem cells iPAPCs inflamed periapical progenitor cells SHED stem cells from human exfoliated deciduous teeth PDLSCs periodontal ligament stem cells BMSCs bone marrow stem cells OESCs oral epithelial stem cells GMSCs gingival-derived mesenchymal stem cells PSCs periosteal stem cells (Yang et al., 2017) Two layers (crown part) Outer - surface Inner - central centrální zevní Dental pulp stratification Unclear zonation in root canal Inner layer / central zone Outer layer Blood and lymph vessels Very rich blood supply (especially at a young age) Arteries (2-10) - Oriented longitudinally through the center of the pulp - Numerous side branches - They divide into terminal networks – odontoblasts supply Subodontoblastic capillary network - Arteries with narrow lumen, thick wall reinforced by several layers of smooth muscle cells - Veins and venules wall very thin, which strikingly contrasts with their wide luminosity Lymph circulation begins with the lymph capillaries that connect to small lymph vessels leaving the dental pulp together with the blood and nerve vessels through the foramen of the apicis radicis dentis Pulp inervation Both myelinated and non-myelinated Myelinated nerve fibres in the dental pulp are rich in branches and reach up to the odontoblast bases under which they form a dense network: Plexus subodontoblasticus Raschkowi the nerve fibres ends on the bodies of the odontoblasts, some enters the predentin and dentin channels Non-myelinated nerve fibres innervate blood vessels in the dental pulp Temperature changes, mechanical or chemical stimuli, osmolarity changes Theories of dental pulp perception a) Nerve endings in pulp and dentin b) Odontoblasts acting as sensory cells c) Hydrodynamic theory Nweeia et al., 2014 Pulp changes during aging • Fastest development immediately after pruning • Age-related changes: chemical composition, structure and volume Chemické složení – amorphous matter loses its mucilaginous character Structure – cell loss, increase of fibres - transformation into dense collagenous connective tissue Volume – loss due to deposition of secondary and tertiary dentin and denticles formation DENTIN dentin Podélný výbrus Dekalcifikovaný řez Microstructure of dentin, dentin types, clinical significance The most abundant dental tissue Living tissue - contains parts of living cells No blood vessels nor bone-lamelar structure Derives from ectomesenchyme Functional and developmental connection with the pulp (dentin-pulp complex) Physical properties Ivory color Harder than bone or cementum, but softer than enamel Refractive index 1.62 (same as enamel) Specific weight 2.14 g/cm3 (lower than enamel) Flexible and permeable (permeability decreases with age) Thickness 2-4 mm (primary dentition half) Comparison of the hard tooth tissues (and lamellar bone) Enamel Dentin Cementum Lamellar bone Colour White (to light blue) Ivory Brown-yellow Brown-yellow Inorganic (%) Organic (%) H20 (%) 96 (86) 1 (2) 3 (11) 70 (45) 20 (30) 10 (25) 61 (33) 27 (31) 12 (36) 45 (23) 30 (37) 25 (40) Collagen fibres NO YES (perpendicular to the dentinal tubules) YES (in all directions) YES (same direction in lamellas) Cells Ameloblasts (missing in adults) Odontoblasts (on the pulpal side of dentin) Cementoblasts (cementocytes) Osteoblasts osteocytes Blood vessels NO NO NO YES (in Haversian canals) Nerves NO YES (on entry of dentinal tubules) NO YES (in Haversian canals) Dentin matrix Consists of collagen fibrils (collagen type I) forming bundles The fibres run parallel to the tooth surface from the root tip to the crown (perpendicular to the the dentin tubules) Amorphous matrix - glycosaminoglycans, proteoglycans and lipids, impregnated with hydroxylapatite crystals In the tubular dentinal matrix, the collagen fibers are missing, contain more hydroxylapatite crystals, compact appearance, about 15% harder than the matrix between the channels Dentin types Primary Secondary Tertiary Secondary dentin Laid down after the root growth is finished, when the crowns have reached the occlusal plane and the teeth are functionally loaded Only for permanent dentition teeth Stored slowly throughout the whole existence of a permanent tooth. Can be separated from the primary dentin by a more pronounced incremental line Secondary dentine deposition results in a reduction in the pulpal cavity Mantle Interglobular Circumpulpal Interdentin Predentin Distance from enamel Enamel Pulp Interdentin Circumpulpal dentin Dentin types Primary Secondary Tertiary Circumpulpal dentin 90 % of all dentin Contains dentinal tubules Interdentin Thin layer between circumpulpal dentin and predentin where dentin mineralization starts Predentin Non-calcified layer near odontoblasts Forms a collagen skeleton for mineralization In both temporary and permanent teeth Interdentin circumpulpal Mantle Interglobular Circumpulpal Interdentin Predentin Distance from enamel Enamel Pulp Dentin types Primary Secondary Tertiary Mantle dentin Firstly-formed dentin, thickness around 30 um Variable mineralization Collagen fibres oriented perpendicular to the DEJ surface (Korff bundles) Branched terminal parts of dentin tubules terminates here Interglobular dentin Imperfectly calcified dentin at the interface of mantle and circumpulpal dentin Fusion of dentin globules is impaired Peritubular Intertubular Relation of odontoblast processes Mantle Interglobular Circumpulpal Interdentin Predentin Distance from enamel Enamel Pulp Dentin types Primary Secondary Tertiary Circumpulpal dentin (von Ebner) • Collagen fibres run obliquely to perpendicular to the course of tubules • Mineralization is globular. • Only minor branching of the dentinal tubules here. ReactiveReparative Damage extent Primary Secondary Tertiary Dentin types Tertiary dentinogenesis Tertiary dentinogenesis Reparative dentin Reactionary dentin? ? Reaction to larger dentin damage Amorphous structure NO Newly differentiated from pulp May be present (osteodentin) Protection from infection Minor stimuli Arranged YES Odontoblasts NO Increase of tooth wall Cause of formation: Structure: Dentinal tubules: Dentin-forming cells: Cell bodies: Main function: Tertiary dentinogenesis Osteodentin Adela Hupková et. Miroslav Králík, 2015 Chemical composition Inorganic 70 % • Hydroxylapatite crystals • Crystals smaller than than in enamel • Crystals attached to fibres Water 10 % Organic 20 % • Collagens - collagen I (III a V) (90 %) • Non-Collagenous Proteins (8%) a) Phosphorins – Ca2+ and phosphate donors, crystal growth control b) Gla-proteins (gamma-carboxyglutamate proteins, acidic character) + glycoproteins (osteonectin, osteopontin, sialoprotein I and II) - calcium carriers, crystal growth c) Proteoglycans - control of crystal growth • Phospholipids (2%) Junctional complex Numerous connecting complexes among the odontoblast apexes: tight junctions, gap junctions, desmosomes synchronization of odontoblasts Above the connecting complexes, the apex slowly changes into a thin and long, short-sided branch Tomes fiber A basal process may be present Each fiber is has its own canal - Dentinal Canal (tubulus) Tomes fibres root crown Channels with Tomes fibres penetrate the entire dentin and cause the dentinal stripes visible on stained sections as well as ground sections Dentinal tubules with Tomes fibres (transversal section) 1 mm2 surface can contain around 50 000 tubules Dentinal tubules (transversal section) Dentinal tubules shape S-shaped (2 bends - primary bending) towards DEJ (or cemento-dentinal junction) Schreger shapes (Crown part of dentin) Primary dential bending In addition to S-shape primary bending, up to another 200 secondary bends Primary and secondary tubular bending caused by migration movements of odontoblasts during dentinogenesis Diameter of the dentin tubules is around 1–4 um Decreasind towards DEJ (or cemento-dentinal junction) Neighboring tubules can be interconnected by anastomoses (tubicles) Enamel spindles (fusus enameli) Dentine tubules extension into enamel Dentin incremental lines Caused by gradual deposition and mineralization of dentin • von Ebner lines - 4-8 um distance - daily increments • Owen's lines - 15-30 µm distance - joint calcification of 4-5 day increments • Neonatal line - Owen line in temporary teeth - separates fetal and postnatal dentine Circular pattern on cross section Sclerotic dentin "Dead Dentin", more resistant to dental caries, color of amber Origin of dentin tubule closure by the thicknessing of peritubular dentin until complete tubules termination Formed in the crown part and increases with age - a sign of aging According to its amount, the age of the individual is determined (forensic)