Dentin - an overview | ScienceDirect Topics It may be concluded that OPN phosphorylation is an important factor in the regulation of OPN-induced mineralization process [103]. Because similar molecules are present in bone and dentin, they may have the same function. Matrix vesicles present at the onset of the outer dentin layers display a hierarchical distribution of membrane phospholipids, coated by proteoglycans, and associated to calcium-binding proteins and enzymes. The root is covered by cementum. The dephosphorylated forms of the fragments all have a less significant effect. Without post-translational modifications the molecular mass of SPARC in ??? The OPN null mice did not have a detectable dental phenotype, and no other data are yet forthcoming to define a role of the molecule in dentinogenesis. Hard inner layer of tooth crown overlying pulp. The tooth enamel protein, porcine amelogenin, is an intrinsically disordered protein with an extended molecular configuration in the monomeric form. The first data obtained with the Transmission Electron Microscope after heart perfusion of the fixative solution established that in the cat, processes are located in the inner third, and never extended more than half distance between the pulp and the DEJ. This finding was corroborated by dot-blot analyses [126], and chemical analysis [127], showing that some acidic phospholipids are actually present during the formation of dentin. The N-terminal region of DPP is distinct from other ECM proteins, however both. Indeed this was a striking feature in newborn and young mice, whereas in the adult such differences were diminished or abolished by what may be compensatory mechanisms. A review of protein structure and gene organisation for proteins associated with mineralised tissue and calcium phosphate stabilisation encoded on human chromosome 4. Different forms of DMP1 play distinct roles in mineralization. After eruption, as a reaction to carious decay or to abrasion, beneath a calciotraumatic line, interpreted as an interruption of normal dentinogenesis, reactionary or tertiary dentin is formed. Matrix gla protein (MGP) is clearly a mineralization inhibitor in many biological models. Immunostaining with CS/DS antibody (2B6) also reveals intensive staining in predentin [40, 41]. Etude par cryofracture. BSP constitutes ~ 1% of the total NCP in dentin [99]. Lipophilia of enamel matrix—a chemical investigation of the neutral lipids and lipophilic proteins of enamel. [130]. Dentin sialoprotein (DSP) has limited effects on in vitro apatite formation and growth. Radioautographic visualization of the deposition of phosphoprotein at the mineralization front in the dentin of the rat incisor. We have observed a reverse situation in predentin, where the collagen fibrils in the Fmod- deficient mice have an increased diameter, as it was the case for BGN-KO mice [24]. Ye L, MacDougall M, Zhang S, Xie Y, Zhang J, Li Z, Lu Y, Mishina Y, Feng JQ. Procollagen binding to sphingomyelin. Jadlowiec JA, Zhang X, Li J, Campbell PG, Sfeir C. Extracellular matrix-mediarted signaling by dentin phosphophoryn involves activation of the Smad pathway independent of bone morphogenetic protein. The same staining pattern is seen with “Stains All” (9). Lussi A, Crenshaw MA, Linde A. Anderson HC. Septier D, Hall RC, Embery G, Goldberg M. Immunoelectron microscopic visualization of pro- and secreted forms of decorin and biglycan in the predentin and during dentin formation in the rat incisor. In the young mice, dentinogenesis was altered, and a type II dentin dysplasia was observed [129]. The possible occurrence of such cell-independent diffusion adds a third possibility to the two previously reported cell-controlled pathways. It is obvious that the effects are modulated by the concentration of the molecule. Phosphorylation of Ser136 is critical for potent bone sialoprotein-mediated nucleation of hydroxyapatite crystals. Often, terminology is not always used in a proper way. Targeted disruption of two small leucine-rich proteoglycans, biglycan and decorin, excerpts divergent effects on enamel and dentin formation. Odontoblasts in their terminal cell division are at first roughly parallel to the BM, but after a short period their great axis is at right angles with the BM. Recent studies [Ferron M, Hinoi E, Karsenty G, Ducy P. Osteocalcin differentially regulates beta cell and adipocyte gene expression and affects the development of metabolic diseases in wild-type mice. Four hours are necessary before silver grains accumulation is seen at the mineralization front [48], whereas in another publication, 1h after the injection labeling starts to develop at the predentin-dentin junction, which is densely labeled at 4h [49]. In addition to physiological primary and secondary dentin formation, reactionary dentin is produced in response to pathological events. Proc Natl Acad Sci U S A. Dentin provides support to enamel, preventing enamel fractures during occlusal loading. However, this last type of so-called “dentin” does not result from the activity of odontoblasts or their associated cells, but specifically from pulp progenitors, implicated in the formation of a bone-like or in structure-less mineralization (pulp diffuse mineralization or pulp stones). Abstract. In vivo expression of mRNA for the Ca++-binding protein SPARC(osteonectin) revealed by In Situ Hybridization. Davis GE, Bayless KJ, Davis MJ, Meininger GA. Regulation of Tissue Injury Responses by the Exposure of Matricryptic Sites within Extracellular Matrix Molecules. Biochemistry. In addition to physiological primary and secondary dentin formation, reactionary dentin is produced in response to pathological events. However, there is not much difference between primary and secondary dentin. Mantle dentin is the outermost thin layer of dentin [] characterized by a low content of highly phosphorylated non-collagenous matrix proteins relative to that in circumpulpal dentin that comprises the rest of the bulk of mineralized dentin layers []. It has long been used by humans as a material in the form of ivory. The Proteoglycan Decorin Links Low Density Lipoproteins with Collagen Type I. GAGs in predentin (PD-PGs) have a rapid turn-over. The molecular weight of this glycoprotein is 60–80 kDa, with high carbohydrate content reported to represent ~ 50% of the molecular weight. Circumpulpal Dentin. Staining is seen in intertubular dentin. Cytoplasmic fatty acid-binding proteins: their structure and genes. Irving JT. More reently it has been recognized that they may also represent a second group of PGs. Taken as a whole, the general composition of dentin is summarized in Table 1. David L, Christiansen, Huang Eric K, Frederick H. Silver Assembly of type I collagen: fusion of fibril subunits and the influence of fibril diameter on mechanical properties. Dental mineralization. von Marschall Z, Fisher LW. The non-phosphorylated recombinant protein acts as a HA nucleator. Therefore DMP-1 is candidate to play role in dentinogenesis, in addition to its signaling properties. The Secreted Protein, Acidic and Rich in Cysteine (SPARC), is as a basement membrane protein (BM-40) alsoknown as osteonectin. In atherosclerotic lesions the proteoglycan decorin links low-density lipoproteins (LDL), sphingomyelin being a constituent of plasma lipoproteins, to collagen Type I [133]. Immunostaining using an anti-MEPE antibody stains the predentin, but not the dentin. In intertubular dentin, s form the plate-like crystallites, 2–5 nm in thickness and 60nm in length. DPP binds to calcium and HA, binds to collagen and induces intrafibrillar mineralization [.Cocking-Johnson D, Sauk JJ. a. Chen S, Gluhak-Heinrich J, Martinez M, Li T, Wu Y, Chuang H-H, Chen L, Dong J, Gay I, MacDougall M. Bone Morphogenetic Protein 2 Mediates Dentin Sialophosphoprotein Expression and Odontoblast Differentiation via NF-Y Signaling. Tiny fibrils accumulate in these vesicles. It can have both positive and negative outcomes and among many examples includes ectopic calcification, vascular calcification and kidney stone formation. Physiologically and anatomically, dentin is a complex structure. One group located in predentin, is probably related to collagen migration and fibrillation. The molecule has been detected in bone at only 1/400th the level as dentin. A chondroitin sulfate chain attached to the bone dentin matrix protein 1 NH2-terminal fragment. Sudanophil inclusions in ameloblasts, odontoblasts and cells of the oral epithelium. This region has been named DMP2 (dentin matrix protein 2), and this part is not phosphorylated. Structural and chemical organization of teeth. It is a highly acidic phosphoserine-rich protein with a high content of aspartic acid. Evidences for a potential role of PGs in dentin mineralization are supported by in vitro studies demonstrating the capacity of biglycan to initiate crystal nuclei [117] and by observations carried out in vivo on biglycan, decorin and fibromodulin KO mice [23,24]. A variety of dentin is substitute dentin, or vasodentin; it is usually in the teeth and scales of fish. The role of BSP in biomineralization may be to mediate the initial stages of connective tissue mineralization, as reviewed in the following references [100, 101]. warfarin) causes secretion of a non-gamma-carboxylated BGP that does not bind to HA,, accumulates in bone and blocks ossification. Type I collagen is the major protein of intertubular dentin (90%), whereas no collagen fibrils are observed in the peritubular dentin. As iss the case for the mantle dentin, this is due either to a defective post-translational modification (ie phosphorylation), or to the absence of these proteins. Adsorption and interactions of dentine phosphoprotein with hydroxyapatite and collagen. However, some hypothesis may be drawn from their physical and chemical -chemical properties. These chains are assembled in a triple helix with a coiled coil conformation [, Fibrillar growth is primarily due to the lateral self-assembly of fibril subunits, followed by a linear fusion implicated in collagen lengthening [, Collagen is synthesized and subsequently controlled by the odontoblasts. Eur J Oral Sci. In dentin extracts DMP-1 appears as fragments with molecular weights between 30 and 45 kDa [92]. Kerebel B, Le Cabellec M-T, Daculsi G, Kerebel L-M. Osteodentine and vascular osteodentine of Anarhichas lupus (L.). In addition to the dose dependency, the time period allowing interaction between the effectors and potential receptors is an important factor modulating the biological outcome. In the proximal predentin (near the cell bodies) the mean diameter of collagen fibrils is about 20nm, whereas in the central part the mean diameter reaches 40nm, and in the distal part, near the mineralization front, fibril diameter vary between 55–75nm [25]. Dentin sialophosphoprotein (DSPP) is cleaved into its two natural dentin matrix products by three isoforms of bone morphogenetic protein-1 (BMP1). The crystal ghosts contain a mixture of proteins, GAGs and phospholipids. Glimcher MJ. J Dent Res. This may apply either to matrix vesicle mineralization. Fibronectin, and then collagen are deposited. Jones SJ, Boyde A. Ultrastructure of dentin and dentinogenesis. In contrast, in horses, the ratio is roughly 50%, and decreases in humans (about 10–20%), with huge variations depending on the area where the calculations are made. Processes are also implicated in the re-internalization of some fragments after the degradation of some ECM molecules. The polyaspartate-containing OPN extracted from one is a mineralization inhibitor that depends on its status phosphorylation Recombinant non-phosphorylated OPN and chemically dephosphorylated OPN have no effect on HA formation. Dentin: Structure, Composition and Mineralization - PMC Dentin sialoprotein and dentin phosphoprotein have distinct roles in dentin mineralization. MEPE’s Diverse Effects on Mineralization. It constitutes the body of teeth and is covered by a hard enamel layer. Dentin is capped by a crown made of highly mineralized and protective enamel, and in the root, it is covered by cementum, a structure implicated in the attachment of the teeth to the bony socket. This supports the existence of two distinct groups of PGs. In dentin, needle-like structures or what has been named crystal ghosts forming a thin organic envelopes wrapping crystallites were stained, but no staining was seen at the mineralization front. Indeed radioautographic data evidence two distinct groups of GAGs in predentin and dentin. It also contains DMP-1, BSP, osteopontin and MEPE. Wang RZ, Weiner S. Strain-structure relations in human teeth using Moiré fringes. Buchaille R, Couble ML, Magloire H, Bleicher F. A substractive PCR-based cDNA library from human odontoblast cells: identification of novel genes expressed in tooth forming cells. Ling Y, Rios HF, Myers ER, Lu Y, Feng JQ, Boskey AL. However, this global distribution provides an oversimplified view, because dentin is a puzzle of different types of dentin, reflecting different functions and bearing their own specificities. They have been reported in the literature as “crystal ghosts”. SPARC mRNA is visualized by in situ hybridization in many soft and hard tissues, including odontoblasts in dentin [110]. Haruyama N, Sreenath TL, Suzuki S, Yao X, Wang Z, Wang Y, Honeycutt C, Iozzo RV, Young MF, Kulkarni AB. Some data obtained in the laboratories of the authors of this article stimulate our interest for the potential role of the two groups of molecules, proteoglycans and lipids, in dentinogensis. Applications of transgenics in studies of bone sialoprotein. Some non-collagenous proteins (NCP) are implicated in the nucleation and growth of the mineral phase, or in its inhibition. Goldberg M, Lécolle S, Vermelin L, Benghezal A, Septier D, Godeau G. [3H]choline uptake and turnover into membrane and extracellular matrix phospholipids, visualized by radioautography in rat incisor dentin and enamel. Are matrix vesicles apoptotic bodies? For the most part, the cells produce the extracellular matrix that is involved in the mineralization process. Butler WT. Indeed the diameter of collagen fibrils is regulated by these proteoglycans as shown by measurements carried out using biglycan- and fibromodulin-deficient mice [23, 24]. Waddington RJ, Hall RC, Embery G, Lloyd DM. During the last mitosis, the daughter cells located near or in contact with the basement membrane (BM) become presecretory prepolarized odontoblasts. Indeed, it was demonstrated that the sudanophilic property is due to the presence of lipophilic proteins and not lipids [124]. Although originally suggested to be derived from apoptotic bodies, recent studies indicate that matrix vesicles are not apoptotic in origin [Kirsch T, Wang W, Pfander D. Functional differences between growth plate apoptotic bodies and matrix vesicles. The molecule is present in odontoblasts, dentinal tubules and ameloblasts. The ivory forming the mass of the tooth. Once released in the proximal predentin, diffusion of the precursor may occur independently and rapidly throughout predentin without direct implication of odontoblasts processes [44, 47]. During dentinogenesis, at least three different sites of mineralization are identified: 1) the cell derived-matrix vesicles driven mineralization occurring mainly in the mantle dentin, 2) the ECM molecules-derived mineralization, accounting for the majority of dentin formation, and 3) The blood-serum derived precipitation occurring in the peritubular dentin. In vitro, in a gelatin gel diffusion system at low concentrations (>25 microg/ml) DSP slightly increase the yield of HA at 3.5 and 5 days. ECM denaturation provides new signals to regulate the tissue response including the mineralization process. However, it has been noted that their number is increased when secretion is impaired by pharmacological drugs such as vinblastine or others vinca alkaloids, or colchicines, a family of drugs that act on the polymerization of cytoskeletal proteins namely tubulin [, Procollagen non-helical extensions are cleaved by procollagen peptidases and the fibrils transformed into native collagen. On a weight basis, dentin is less mineralized than enamel (96% in weight), but more than bone or cementum (about 65% in weight). The molecule consists of 300 amino acids, plus a 17amino acids signal peptide. These PGs are stable, incorporated into the forming dentin and become dentin components associated with mineralization [44]. There have been a variety of attempts to identify the proteins and other matrix components implicated in dentinogensis. Odontoblasts are aligned at the surface of the dental pulp. They display some elastic properties and therefore provide some resilience, important from a mechanical point of view and allowing dissipation of stress forces [7]. Later, the band is covered by the dentin newly formed during the next 48h and more, which is not labeled. The Hyp mice model is a model for X-link hypophosphatemic rickets. Phylogenetic studies have revealed that during evolution, originally dentin analogues were very similar to bone, with osteoblast/odontoblast-like cells located within alveoli, as it is the case for osteocytes surrounded by bone within lacunae [1,2]. They are more numerous in the inner third layer than the outer third layer of the dentin. In the maxilla in the median region, odontoblasts precursors migrate from the fronto-nasal bud. The circumpulpal dentin forms the largest part of the dentin layer. However, the thickness of the outer layer is about 200mm, therefore larger than the presumed width of the mantle dentin. Somogyi E, Petersson U, Sugars RV, Hultenby K, Wendel M. Nucleobindin—a Ca -Binding Protein Present in the Cells and Mineralized Tissues of the Tooth. The growth of these crystals is also directed by the ECM proteins. To summarize this section, DPP or phosphophoryn appears as candidate to be implicated in intertubular dentin mineralization. No staining is observed over predentin. Dentine meaning states that it is composed of 45 percent mineral hydroxyapatite, 33 percent . The interaction between phosphoproteins, lipoproteins, proteoglycans may coat the oriented crystals. Kagayama M, Sasano Y, Tssuchia M, Watanabe M, Mizoguchi I, Kamakura S, Motegi K. Confocal microscopy of Tomes’s granular layer in dog premolar teeth. Gafni G, Septier D, Goldberg M. Effect of chondroitin sulphate and biglycan on the crystallisation of hydroxyapatite under physiological conditions. DSPP KO mice display tooth alterations that are very similar to the human dentinogenesis imperfecta type III [82]. Prockop DJ, Sieron AL, Li SW. Procollagen N-proteinase and procollagen C-proteinase. As a library, NLM provides access to scientific literature. Circumpulpal dentin may be 6 to 8 mm thick in the crown and a little thinner in the roots. Orimo H. The mechanism of mineralization and the role of alkaline phosphatase in health and disease. 2006 Mar 24;281(12):8034-40]. This is found in cell cultures, in very young animals, or when defective collagen synthesis occurs. In contrast procollagen I bind strongly to sphingomyelin in a reversible and storable manner. This is why, under a generic name of dentinogenesis, different types of mineralization are producing specifically very different tissues. Changes in phospholipid composition accompany mineralization of chicken growth plate cartilage matrix vesicles. TGF-. Circumpulpal dentin forming the bulk of the tooth, comprises intertubular and peritubular dentin. After mild demineralization no collagen fibrils are detectable, but a thin network of non-collagenous proteins and phospholipids are visible [15, 18, 19]. Deletion of Dentin Matrix Protein-1 leads to a partial failure of maturation of predentin into dentin, hypomineralization, and expanded cavities of pulp and root canal during postnatal tooth development. Among the genes expressed in rat incisors, the most abundant code for osteonectin, alpha1 (I) and alpha2 (I) collagen, and decorin [63]. Enzymes such as alkaline phosphatase, a Zn- and Mg- containing enzyme, and cation biinding proteins derived from the blood serum and other molecules listed in Table 3 have been identified in dentin extracts.