Enamel, cementum Jan Křivánek 7. 4. 2021 Image result for enamel human tooth A Review of Dental Tissue Microstructure, Biomodification, and Adhesion | Special Issues Related image Image result for mole rat •Enamel •(enamelum, enamel, email, substantia adamantina, s. vitrea) ENAMEL (enamelum, email, substantia adamantina, s. vitrea, sklovina) -Tissue covering tooth crowns -Ectodermal origin -Hardest tissue (fragile) in the vertebrates bodies -Acelular Thickness: Permanent dentition +- 2,5 mm Primary dentition +- 1,3 mm Tooth neck +- 0,1 mm Physical properties -Refractive index: 1,62; density: 2,9 g.cm-3, -Mohs scale hardness 5 -Translucent, color – white shades – depends on thickness and mineralization degree Grey-white – occlusion sides White – middle part of crown Yellowish – near the neck (dentin bellow) High resistence to abrasion -Denser, harder and less porous in the surface (aprismatic) -Hardness is decreasing towards DEJ (dentino-enamel junction) and from top of crown towards the neck Image result for mohs hardness NON-collagenous proteins a)Amelogenins -90 % -Main product of ameloblasts secretory stage -Spherical polymers, regulation of enamel prisms growth b)Non-amelogenins: -Enamelin – Nucleation and direction of growth regulation of crystals -Ameloblastin – Adhesive molecule -Kalikrein 4 – Protease secreted by ameloblasts in the final sectretory stage -Tuftelin – Stabilizes connection to dentin c)Proteins with enzymatic activity -Metaloproteases (MMP20) – amelogenin degradation -Alkalic phosphatase, phosphomonoesterase and serinprotease 1 Frontiers | Amelogenesis Imperfecta; Genes, Proteins, and Pathways | Physiology Chemical composition Inorganic 96 - 97 % Water 2 - 3 % Organic 1 % https://pocketdentistry.com/wp-content/uploads/285/c04f002.gif Microscopis structure Complicated and species-specific inner structure Enamel prisms (prisms and interprismatic substance), +-1 µm wide Direction: from DEJ up to the surface, approx. 8,5 milions (incisivi) https://www.researchgate.net/profile/Stefan_Habelitz/publication/274086153/figure/fig2/AS:416101423 960065@1476217718134/Relationship-among-the-Tomes-process-the-pits-and-rod-interrod-development-in. png https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcS8XMrnOu6qQXS3ge3OxANHhild8sZOk-cl1YKONbwphOX MZbV0nA Figure_07-01 Prisms ultrastructure Consists of longitudinal arranged crystals of hydroxyapatite, inserted into proteinous matrix (amelogenins, non-amelogenins) Interprizmatic substance structure is the same, but crystals are laid down under different angle Figure_07-02 5 Enamel decussation pattern (rodents) •Very precise and homogeneous organization of enamel microstructure •Little differences within different species •Fundamental mechanisms controlling decussation pattern formation are evolutionary conserved Daniela C. Kalthoff, 2007 Longitudinal section of the Wood Mouse, Apodemus sylvaticus, showing typical uniserial enamel. Enamel-dentine-junction to the left, outer enamel surface to the right. Image: Daniela C. Kalthoff Wood Mouse (Apodemus sylvaticus) Daniela C. Kalthoff Goldberg et al, 2014 Mus musculus Heterosminthus gansus (late Miocene) Fig. 3. (a) “Secretory ameloblasts of rat incisor during development of inner enamel showing alternate inclinations of proximal ends of cells in alternating transverse rows, which are sliding past one another at this stage of development. Papillary cells are seen at the top of field of view, enamel at the bottom” (quoted caption and image from (Boyde, 1989)). (b) Schematic of cells in (a), with the cell tips marked by tip points, e.g., x4. The trajectory of Tomes’ process, on average, shadows the trajectory of the cell tip, as illustrated for cell 4. https://www.researchgate.net/profile/Lyle_Gordon/publication/274728288/figure/fig1/AS:2715636059341 03@1441757217968/Overview-of-mouse-incisor-enamel-structure-A-B-SEM-images-of-a-lactic-acid-etched. png Overview of mouse incisor enamel structure. (A,B) SEM images of a lactic acid-etched cross-section reveal decussating rods composed of thousands of high-aspect ratio hydroxylapatite nanowires. Scale bars in (A,B) correspond to 4 μm and 250 nm, respectively. (C) In this bright-field TEM image of a FIB-prepared thin section of the edge of one mouse enamel rod, parallel alignment of nanowires is apparent. Scale bar corresponds to 200 nm. Bridging the gap: 3D real-space characterization of colloidal assemblies via FIB-SEM tomography - Nanoscale (RSC Publishing) DOI:10.1039/C8NR09753D A schematic drawing showing the FIB-SEM geometry, and a low... | Download Scientific Diagram Welcome To Tiny Town | Tacky Raccoons External characteristics of enamel RetziusovyLinie https://www.researchgate.net/profile/Fernando_Ramirez_Rozzi/publication/13510703/figure/fig2/AS:661 606069444608@1534750587171/Schematic-section-of-a-tooth-showing-incremental-lines-in-enamel-The-num ber-of.png Striae of Retzius Perikymata Hunter - Schreger bands Neonatal line Enamel tuffs External characteristics of enamel Hunter - Schreger bands Gabriel-Philippe de la Hire and the discovery of Hunter-Schreger bands | British Dental Journal Lynch et al., British dental journal, 2010 Course of Hunter-Schreger bands (HSB) on: the buccal side of M 2 from... | Download Scientific Diagram Course of Hunter-Schreger bands (HSB) on: the buccal side of M 2 from Ursus spelaeus (A), the buccal side of P 4 from Felis catus (B), the U. wenzensis M 2 viewed from the lingual and occlusal side (C) and the buccal side of M 1 from U. wenzensis. Nowakowski et al., 2010 •Consequence of changes in the direction of prisms •The course of enamel prisms changes in all directions, especially in premolars and molars. •Optically, they appear as alternating lighter and darker bands Incremental enamel bands The enamel grows periodically: the influence of circadian rhythms Manifestation of periodic activity of ameloblasts or joint mineralization of a larger number of daily incremental lines Based on the incremental lines, we distinguish the characteristic types of incremental bands a) Daily incremental lines -Cause prisms cross-striation, very thin (2,5 - 6 μm) -Circardial rhytms influenced -Alternation of the phase of intense secretion with the resting phase - b) Stripes of Retzius (Retzium lines; enamel striae) -Can be observed under optical microscope on ground sections (25-35 μm) -From DEJ to enamel surface -Forms perikymata - c) Neonatal line -A distinctive stripe of less mineralized enamel -In primary dentition and M1 -It belongs to the Retzius line -Due to abrupt change in nutrition at birth https://www.researchgate.net/profile/Fernando_Ramirez_Rozzi/publication/13510703/figure/fig2/AS:661 606069444608@1534750587171/Schematic-section-of-a-tooth-showing-incremental-lines-in-enamel-The-num ber-of.png Enamel incremental periodicity. Top: Daily (circadian) growth lines, or cross-striations (short arrows) are observed between adjacent long-period (multidien) striae of Retzius (long arrows) (distance between the adjacent striae of Retzius shown = 30 μm). Bottom: Striae of Retzius may be seen to course across the horizontal field of view (FW = 450 μm). The number of cross-striations between adjacent striae of Retzius is termed the "repeat period" (RP). In this instance the molar enamel from one of the authors (TGB), the RP = 8 (see Fig 2). (Timothy G. Bromage et al., 2015, American Journal of Physical Anthropology; Hard Tissue Biology, Metabolomics, and Life History) Daily incremental lines Daily (circadian) growth lines, or cross-striations (short arrows) are observed between adjacent long-period (multidien) striae of Retzius (long arrows) Striae of Retzius may be seen to course across the horizontal field of view. The number of cross-striations between adjacent striae of Retzius is termed the "repeat period" (RP). Swine enamel circadian and multidien rhythms. Dark banding across the horizontal field are striae of Retzius (long arrows), while 5 daily events may be seen between adjacent striae (short arrows) (FW = 1 mm). doi:10.1371/journal.pone.0145919.g003 (Timothy G. Bromage et al., 2015, American Journal of Physical Anthropology; Hard Tissue Biology, Metabolomics, and Life History) Swine enamel circadian and multidien rhythms. Dark banding across the horizontal field are striae of Retzius (long arrows), while 5 daily events may be seen between adjacent striae (short arrows) Daily incremental lines https://slideplayer.com/slide/1663140/7/images/31/Enamel+Dentin+Lines+of+Retzius+Lines+of+Owen+Dent ino-enamel+Junction.jpg It belongs to a series of a growth lines in tooth enamel known as the Striae of Retzius. Průběh hranolů v horizontálních řadách od dentinu k povrchu skloviny, osa prizmat postavena kolmo k dentinu (resp. DSH) nebo povrch korunky ve středních partiích skloviny se hranoly spirálovitě obtáčejí na podélných výbrusech zubem radiální pruhování, zvané -Hunterovy - Schregerovy proužky Striae of Retzius It belongs to a series of a growth lines in tooth enamel known as the Striae of Retzius. Figure_07-59 Figure_053 Striae of Retzius Perikymata Figure_054 Neonatal line Figure_054 Incremental enamel bands The enamel grows periodically: the influence of circadian rhythms Manifestation of periodic activity of ameloblasts or joint mineralization of a larger number of daily incremental lines Based on the incremental lines, we distinguish the characteristic types of incremental bands a) Daily incremental lines -Cause prisms cross-striation, very thin (2,5 - 6 μm) -Circardial rhytms influenced -Alternation of the phase of intense secretion with the resting phase - b) Stripes of Retzius (Retzium lines; enamel striae) -Can be observed under optical microscope on ground sections (25-35 μm) -From DEJ to enamel surface -Forms perikymata - c) Neonatal line -A distinctive stripe of less mineralized enamel -In primary dentition and M1 -It belongs to the Retzius line -Due to abrupt change in nutrition at birth Aprismatic enamel •20-70 um wide layer on the surface of crown enamel •Harder and more mineralized. Contains more fluoride •Is formed just before the end of ameloblasts aktivity •Hydroxyapatite crystals are hightly packed and perpendicular to enamel surface obr29 Enamel types and variation in crystallite volume of prismatic enamel... | Download Scientific Diagram Giant panda׳s tooth enamel: Structure, mechanical behavior and toughening mechanisms under indentation - ScienceDirect Figure_07-37 Figure_062 DEJ (Dentino-Enamel Junction) • •The boundary between the enamel and the dentin, forms the functional connection of these two hard tissues •Developmentally, it is located at the site of the (disintegrated) basal membrane of ameloblasts •It has wavy structure •Multiple small holes where enamel prisms bundles are connected Diagram of molar anatomy depicting age-related landmarks [dentin enamel... | Download Scientific Diagram the primary enamel cuticle, consisting of two extremely thin layers (the inner one clear and struct ureless, the outer cellular), covering the entire crown of newly erupted teeth and subsequently abr aded by mastication; it is evident microscopically as an amorphous material between the attachment epithelium and the tooth. Cuticula dentis (Nasmyth's membrane) • •Covers a newly erupted tooth, after eruption its remnants can only be seen near the tooth neck •A thin cuticular structure - remains of the enamel organ •Formed by proteins and polysaccharides •1 um wide, remains on the surface of primary dentition nearby the neck • PPT - TOOTH & RELATED TISSUES: Developmental goal PowerPoint Presentation - ID:4098109 Figure_063 Enamel spindles (fuzus enameli) Up to 100 um prolongation of dentin tubules into enamel cement_sklhranice Cementum-enamel border 3 types: Cementum overlap over enamel sharp line with gap 15 % (60 %) 52 % (30 %) 33 % (10 %) Enamel regeneration Enamel do NOT regenerate! Ameloblasts became apoptotic during eruption Enamel hypoplasia Enamel is soft and fragile Etiology: •Ameloblasts damage and/or premature end of their function •Genetical disorders (amelogenesis imperfecta) •Longterm increase of fluorides income (5x higher increase of fluorides in drinking water) •Tetracykline antibiotics – incorporation into enamel during calcification •High fevers • Image result for amelogenesis imperfecta http://www.jcda.ca/sites/default/files/d38/fig3.png https://upload.wikimedia.org/wikipedia/commons/thumb/1/1c/A_amelogenesis_imperfecta.jpg/220px-A_ame logenesis_imperfecta.jpg Enamel reparation Remineralization of damaged enamel by the action of saliva • • • Age related changes in enamel -Abrasion - in more advanced stages, dentin exposure may occur -Change of chemical composition - increasing the content of fluorides, reducing of the water and organic compounds -Change in enamel pigmentation - incorporation of organic material into the enamel, dentin thickening and darkening -Permeability changes - decreases with age, crystals grow during life and the pores between them shrink Attrition: loss of enamel, dentin, or restoration by tooth-to-tooth... | Download Scientific Diagram How Can I Get Rid of Yellow Teeth? | Old Town Smiles Abrasion - in more advanced stages, dentin exposure may occur Change of chemical composition - increasing the content of fluorides, reducing the content of water and organic compounds Change in enamel pigmentation - incorporation of organic material into the enamel, dentin thickening and darkening Permeability changes - decreases with age, crystals grow during life and the pores between them shrink Cementum (cementum, substantia petrosa) Image result for cement •Hard, bone-like tissue covering the root of the tooth •Yellowish color •Avascular tissue •Does NOT rebuild (in contrast to bone) •Can be resorbed by cementoclasts - during the tooth replacement •It is continuously deposited by new layers formation. Growth related to circardial rhytms – incremental lines. •Development from ectomesenchyme • Composed of: •Cellular part •ECM Cementum Image result for cementum What Is Cementum? - Vibrant Smiles Mableton GA Dentist Dr Chea Rainford •Collagen fibers (especially collagen 1) of periodontal ligaments, which are immersed on the one side in cementum and on the other side in the periosteum of alveolar bone •It forms a functional attachment of the tooth in the alveolus •They run all the way to acellular cementum, where they are fully mineralized • Sharpey fibers Periodontium Equine dental and periodontal anatomy: A tutorial review - Staszyk - 2015 - Equine Veterinary Education - Wiley Online Library Collagen fibers (especially collagen 1) of periodontal ligaments, which are immersed on the one side in cementum and on the other side in the periosteum of alveolar bone It forms a functional attachment of the tooth in the alveolus They run all the way to acellular cementum, where they are fully mineralized https://pocketdentistry.com/wp-content/uploads/285/F000196f10-02-9780323082563.jpg Figure_080 Microscopic anatomy Cementocytes, Cementoblasts, (Cementoclasts) Extracellular matris (ECM) = Cementum Cementoblasts Actively involved in ECM formation Cementocytes Cells surrounded by cementous tissue, bodies placed in cavities (lacunae), processes in small tubules (similar to Osteocytes in Bone) - canaliculi cementi Cementoclasts Involved in cementum resorbation in temporary teeth Acelular (primary) Celular (secondary) Cells cement_rozlozeni Cementum matrix Collagen fibres and calcified amorphous mass Collagen fibres run in bundles (orientation is determined by the forces on teeth) Cementum is divided by origin into: Primary (acellular) Does not contain cementocytes In the range of the entire tooth root Directly connected to the dentine Thickness: 10 to 200 µm Secondary (cellular) Contains cementocytes Especially on dental apexes Grows up to 500 µm thick Prim_sekCement.jpg Prim_sekCement.jpg • • •Cementum hyperplasia •(hypercementosis) • •Abnormal cement thickening •Occurs either in single tooth/teeth or in a whole dentition (Paget's disease) •The most frequent cause of hypercementosis is long-term and excessive tooth load •Cementicles – in PDL exostozy Cementum, apical morphology and hypercementosis: a probable adaptive response of the periodontal support tissues and potential orthodontic implications hypercement Hypercement.jpg hypercement Thank you for your attention!