Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ODONTOBLASTS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 973 records · Page 54Linked to original sources
PubMed2003

Cadherin-related neuronal receptors in incisor development.

Cadherins are cell adhesion molecules that are critical for tissue development. In this report, we identified members of the cadherin family cadherin-related neuronal receptors (CNRs) 1 and 5 expressed in rat incisors by the differential display method. Quantitative RT-PCR revealed that CNR1 mRNA is expressed in the secretory stage but reduced in the early-maturation stage, while CNR5 mRNA is expressed in both these stages. In situ hybridization showed that strong expression of CNR1 is strong in the secretory stage, but reduced in the early phase and diminished in the late phase of the early-maturation stage. CNR5 mRNA is expressed almost at the same levels in the secretory and in the early phase of the early-maturation stages but is absent in the late phase of the early-maturation stage. Both CNR1 and 5 mRNA are continuously expressed in odontoblasts. Immunohistology showed that CNR proteins are expressed in the secretory and early-maturation stages of ameloblasts, but no protein expression at the late-maturation stage was observed. CNR proteins were continuously expressed in odontoblasts. We found that recombinant CNR1 binds dental epithelial and mesenchymal cells through N-terminal domain EC1 in vitro. These results suggest that CNR1 and CNR5 may play an important role in enamel and dentin formation, probably through cell-cell and/or cell-matrix interactions.

Ameloblasts↗
PubMed2005

Mouse amelogenin exons 8 and 9: sequence analysis and protein distribution.

Amelogenin is the major protein of the developing enamel. Two additional exons, termed 8 and 9, have been characterized in the rat. Our aim was: to identify the mouse amelogenin exons 8/9 sequences; to investigate the potential presence of the alternative spliced isoforms of amelogenin exons 8/9; and to immunolocalize proteins containing sequences encoded by exons 8/9 during odontogenesis. RT-PCR analysis with exon 9 anti-sense primer generated 2 major amplicons with the use of a mouse tooth cDNA library and dental cell lines. DNA sequence analysis showed 93% identify with the rat exons 8/9 sequence. Alternative splicing of exon 3 was also found, but only in cDNAs lacking exons 8 and 9. Immunohistochemistry localized exons 8/9-encoded proteins in ameloblasts, young odontoblasts, and stratum intermedium cells. Analysis of our data supports the hypothesis that: (1) AMELX contains 2 additional exons; (2) ameloblasts and odontoblasts synthesize amelogenin 8/9; and (3) amelogenin splice variants may have unique functions during tooth formation.

Alternative Splicing↗
PubMed2003

Comparative genomics and structure prediction of dental matrix proteins.

Non-collagenous matrix proteins secreted by the ameloblasts (amelogenin) and odontoblasts (osteocalcin) play important roles in the mineralization of enamel and dentin. In this study, comparative genomics approaches were used to identify the functional domains and model the three-dimensional structure of amelogenin and osteocalcin, respectively. Multiple sequence analysis of amelogenin in different species showed a high degree of sequence conservation at the nucleotide and protein levels. At the protein level, motifs (a sequence pattern that occurs repeatedly in a group of related proteins or genes), conserved domains, secondary structural characteristics, and functional sites of amelogenin from lower phyla were similar to those of the higher-level mammals, reflecting the high degree of sequence conservation during vertebrate evolution. Osteocalcin, produced by both odontoblasts and osetoblasts, also showed sequence similarity between species. Three-dimensional structure predictions developed by modeling of conserved domains of osteocalcin supported a role for glutamic acid residues in the calcium mineralization process.

Ameloblasts↗
PubMed2002

Phospholipids in amelogenesis and dentinogenesis.

Phospholipids have been identified in enamel and dentin. Before demineralization, a group of phospholipids extracted by lipid solvents was associated with cell membranes and is therefore closely related to cell growth and intracellular regulations. After demineralization, a second group of phospholipids, associated with the extracellular matrix, was extracted; this group is probably linked to the mineralized phase. Using imidazole-osmium tetroxide fixation of rat incisors, we stained cellular unsaturated fatty acids, so that we could visualize the membrane domains, coated pits, and endocytic inclusions. Filipin, a probe for cholesterol, varied in density along the plasma membrane of secretory ameloblasts, and allowed us to visualize membrane remnants inside the forming enamel. With respect to phospholipids located in the extracellular matrix, the malachite-green-glutaraldehyde (MGA) method or iodoplatinate (IP) reaction retains and visualizes enamel and dentin phospholipids. In predentin, aggregates appearing as granules and filaments, or liposome-like structures, were located in the spaces between collagen fibrils. In dentin, organic envelopes coating the crystals, also named "crystal-ghost" structures, outlined groups of collagen fibrils. Histochemical data provided evidence that phospholipids are co-distributed or interact with proteoglycans. Radioautography after IP reaction established that [3H] choline was detected in dentin as early as 30 min after the intravenous injection of the labeled precursor, before any labeling was seen in odontoblasts and predentin. This suggests that blood-serum-labeled phospholipids pass between odontoblasts, cross the distal permeable junctional complex, and diffuse in dentin prior to any cellular uptake and phospholipid synthesis. Pharmacologically and genetically induced pathology also supports the suggestion that phospholipids play an important role in the formation and mineralization of dental tissues.

Ameloblasts↗
PubMed1979

Immunohistochemical localization of procollagens. I. Light microscopic distribution of procollagen I, III and IV antigenicity in the rat incisor tooth by the indirect peroxidase-anti-peroxidase method.

Frozen sections of the growing end of the rat incisor tooth were exposed to antisera or affinity prepared antibodies against partially purified type I, II, or IV procollagen in the hope of detecting the location of the corresponding antigens by the peroxidase-anti-peroxidase technique. The distribution of immunostaining was similar with antisera as with purified antibodies of a given type, but differed for each type; that is, predentin, odontoblasts, pulp and periodontal tissue were the sites of type I; blood vessel walls, pulp and periodontal tissue, of type III; and basement membranes, of type IV antigenicity. It was demonstrated, at least in cases of type I and III, that immunostaining detected the corresponding procollagens and related substances, but not the corresponding collagens. The interpretation of these observations is that: 1) odontoblasts elaborate procollagen I for release to predentin and subsequent transformation to dentinal collagen I; 2) pulp and periodontal cells produce procollagens I and III which presumably become collagens I and III respectively, while the adventitial cells of blood vessels give rise to collagen III; and 3) procollagen IV is associated with basement membranes and, occasionally, adjacent cells.

Animals↗
PubMed2000

BMP4 rescues a non-cell-autonomous function of Msx1 in tooth development.

The development of many organs depends on sequential epithelial-mesenchymal interactions, and the developing tooth germ provides a powerful model for elucidating the nature of these inductive tissue interactions. In Msx1-deficient mice, tooth development arrests at the bud stage when Msx1 is required for the expression of Bmp4 and Fgf3 in the dental mesenchyme (Bei, M. and Maas, R. (1998) Development 125, 4325-4333). To define the tissue requirements for Msx1 function, we performed tissue recombinations between wild-type and Msx1 mutant dental epithelium and mesenchyme. We show that through the E14.5 cap stage of tooth development, Msx1 is required in the dental mesenchyme for tooth formation. After the cap stage, however, tooth development becomes Msx1 independent, although our experiments identify a further late function of Msx1 in odontoblast and dental pulp survival. These results suggest that prior to the cap stage, the dental epithelium receives an Msx1-dependent signal from the dental mesenchyme that is necessary for tooth formation. To further test this hypothesis, Msx1 mutant tooth germs were first cultured with either BMP4 or with various FGFs for two days in vitro and then grown under the kidney capsule of syngeneic mice to permit completion of organogenesis and terminal differentiation. Previously, using an in vitro culture system, we showed that BMP4 stimulated the growth of Msx1 mutant dental epithelium (Chen, Y., Bei, M. Woo, I., Satokata, I. and Maas, R. (1996). Development 122, 3035-3044). Using the more powerful kidney capsule grafting procedure, we now show that when added to explanted Msx1-deficient tooth germs prior to grafting, BMP4 rescues Msx1 mutant tooth germs all the way to definitive stages of enamel and dentin formation. Collectively, these results establish a transient functional requirement for Msx1 in the dental mesenchyme that is almost fully supplied by BMP4 alone, and not by FGFs. In addition, they formally prove the postulated downstream relationship of BMP4 with respect to Msx1, establish the non-cell-autonomous nature of Msx1 during odontogenesis, and disclose an additional late survival function for Msx1 in odontoblasts and dental pulp.

Animals↗
PubMed1978

Human pulpal response to citric acid cavity cleanser.

Treatment of cavities with citric acid cavity cleanser, also used as an etchant, before restoration with zinc oxide-eugenol cement, was toxic to the human dental pulp in comparison to sham-treated controls. The cleanser caused a significantly (P less than .01) greater intensity and incidence (P less than .01) of inflammation. The added insult from cleanser pretreatment caused destruction of the odontoblast processes withnin the cut dentinal tubules, and an increase in diameter of the tubules. These effects on dentin and odontoblasts probably contributed to the observed increase in adverse pulp responses.

Adolescent↗
PubMed1992

Immunoelectron microscopic observation of calcitonin gene-related peptide (CGRP)-positive nerves in the dental pulp of rat molars.

The ultrastructure of nerves containing immunoreactivity for calcitonin gene-related peptide (CGRP) was investigated in the dental pulp of rat molars. The immunoreactivity was recognized predominantly in unmyelinated nerve fibers, and sparsely in a few myelinated fibers. It was localized throughout the axoplasm, as well as in the large cored vesicles. Small clear vesicles and mitochondria were free of the immunoreaction. The CGRP-immunoreactive nerves were frequently observed to terminate, being devoid of Schwann cell investment, in the vicinity of blood vessels in the coronal pulp, suggesting that CGRP may be involved in the regulation of pulpal blood flow. Moreover, CGRP-immunoreactive axon terminals containing numerous small clear vesicles, a few large cored vesicles and mitochondria were recognized in contact with the cell bodies of odontoblasts and their processes in the dentinal tubules. Although specialized synaptic ultrastructures were not recognizable, a functional association of CGRP nerves and odontoblasts was suggested. Thus, CGRP in the dental pulp appears to have multiple functions, including vascular regulation and sensory transduction.

Animals↗
PubMed2005

Immunocytochemical localization of the neurokinin 1 receptor in rat dental pulp.

The dentin-pulp complex is a peripheral end-organ supplied by dense sensory nerve fibers. Substance P, a representative neuropeptide widely distributed in the dental pulp, has been reported to play roles in pain transmission and the amplification of inflammation. We analyzed here the expression of the neurokinin 1 (NK1) receptor, preferentially activated by substance P, using immunocytochemistry in rat dental pulp at both the light and electron microscopic levels. Conspicuous NK1 receptor immunoreactivity was found in the odontoblasts; immunolabelings were present at their plasma membrane and endosomal structures, especially in their cytoplasmic processes. Immunoreactions for NK1 receptor were also detectable in a part of the nerve terminals associated with the cytoplasmic processes of the odontoblasts. Furthermore, the endothelial cells of capillaries and post-capillary venules and the fibroblasts were labeled with the NK1 receptor in the subodontoblast layer. These findings suggest that pulpal cells and nerve fibers are targets for substance P that mediate multiple functions, including a vasoactive function and the regulation of vascular permeability as well as the modulation of pain transmission.

Amino Acid Sequence↗
PubMed1978

Ultrastructural and cytochemical studies on the matrix vesicle calcification in the teeth of the killifish, Oryzias latipes.

Tooth germs of killifish were examined by both ultrastructural and cytochemical methods. The ultrastructure of the dentin in the early calcification stage of its development resembled that of mammals. Numerous extracellular membrane-bounded vesicles, matrix vesicles, were seen in the predentinal space, especially abundantly in the basal portion of the tooth germ. They were more numerous and more uniform in appearance than in any other higher vertebrates. Where calcification was going to start, slightly identifiable needles of apatite crystals were found in the vesicular structures. Crystals increase in number filling up the vesicles and then ther surroundings, finally to form many calcified spherules. Where calcification was more extensive, the matrix vesicles were no longer visible having been buried calcified among spherules. Contrary, to popular belief, there was no relationship seen between collagen fibrils and the initial deposits of minerals, that is, collagen fibrils did not seem to work as the initial site of calcification. Instead, matrix vesicles and plasma membranes of odontoblasts likely were involved in calcification as they both showed alkaline phosphatase activity. The ultrastructural and cytochemical findings from this study thus indicated that calcification of the killifish tooth germs was initiated not in the enamel, but in their dentin by the matrix vesicles which were liberated into the dentin matrix from odontoblasts mainly by way of fragmentation of cell processes.

Animals↗
PubMed2002

Pulpal response to different pulp capping methods after pulp exposure by air abrasion.

Air abrasion is regaining popularity especially in the area of pediatric dentistry due to its ease of use and its advantages. Due to the lost of tactile information, while using this technique, there is an increased risk for pulpal exposure. On the other hand, Ca(OH)2 medicament has been proven to induce dentin bridge formation, but an adequate sealing seems to be even more important that the capping material used. The purpose of this study was two fold: to assess the pulpal response after pulpal exposure by air abrasion and to evaluate the healing potential after using Ca(OH)2 medicament or Liner Bond II as a capping agent. Two hundred sixteen teeth from mixed-bred dogs were used in this study. The teeth were divided into three groups, A) pulpal exposure by air-abrasion followed by sealing of the cavity with Liner Bond II, B) pulpal exposure by air-abrasion and Ca(OH)2 pulp capping and C) pulpal exposure by high-speed followed by air-abrasion and Ca(OH)2 pulp capping as a control group. The animals were sacrificed after 7, 14, 30 and 60 days and a histopathological evaluation was undertaken. After applying Analysis of Variance to compare the groups, it was observed that at earlier observation periods, the inflammatory criteria near the exposure site were different among the groups. As time elapsed, the inflammation was resolved in the pulp tissue, however, the odontoblastic layer and the dentin bridge formation had a highly statistically significant difference (p<0.001) among the various groups at all observation periods. In addition, a positive correlation was observed between the organization of the odontoblastic layer and the dentin bridge formation mainly after 30 days. It could be concluded that dentin bridge formation could be achieved with the use of Ca(OH) or Liner Bond II as capping agent with an adequate sealing. However, the formation is delayed especially when Liner Bond II is used as capping agent.

Acrylic Resins↗
PubMed1989

[Lectin-binding sites in the growing end of rat incisors].

Tooth germs of rat incisors were examined by lectin-histochemistry in the portion from the apical end to enamel forming stage. Tissue sections were prepared from paraformaldehyde-fixed and paraffin-embedded tissues with or without EDTA-decalcification. They were stained with fluorescein-isothiocyanate-labeled (F- for short) lectins and observed by a fluorescent microscope. The boundary between inner enamel epithelia and dental papilla cells was stained with F-Con A, F-MPA and F-PNA. The boundary between the epithelia and dentin was stained with F-Con A and F-MPA. Stratum intermedium cells were stained with F-Con A, F-MPA and F-PNA, and were different in the time when they began to be stained with each lectin during their development. Distal cytoplasm of secretory ameloblasts and odontoblasts were stained with F-MPA and F-Con A, respectively. The staining with these lecting became stronger gradually from the apical to the incisal side. These results suggest that F-MPA and F-Con A are useful as a marker indicating the time when enamel and dentin begins to form, respectively. Distal cytoplasm of secretory ameloblasts was also stained with F-Con A and F-PNA. The odontoblastic layer was stained only with F-Con A, but the dental papilla was stained with F-Con A, F-MPA, and F-PNA. Stellate reticulum and outer enamel epithelia were stained with F-Con A and F-MPA. The comparison of the results from decalcified and non-decalcified tissues showed that the EDTA-decalcification scarcely affected these lectin bindings.

Amelogenesis↗
PubMed1989

An electron-microscopic observation on the collagen fibril arrangement in the outermost layer of dog dentine as revealed by tangential sections.

In the forming initial dentine, each odontoblast extended a thick process perpendicularly to the basal lamina, and the collagen fibrils formed were divided into two groups based on their orientation. One was a group of fibrils running parallel to an odontoblastic process to organize the peri-process fibril bundles to organize the inter-process fibril bundles. This pattern of fibril orientation was similar in both crown and root. The diameter of each collagen fibril ranged from 30-100 nm in the crown and from 30-180 nm in the root.

Animals↗
PubMed1979

Innervation of different parts of the predentin and dentin in young human premolars.

The innervation of the predentin and inner part of the mineralized dentin was studied at the ultrastructural level in ten premolars. Each tooth was divided into fifteen different parts, each containing odontoblasts, predentin and dentin. It was found that the innervation in the coronal dentin was more compact than in the root dentin. Within the coronal dentin itself, the most densely innervated area was the dentin covering the pulp horns. No nerves were identified more than 100 microns from the pulp-dentinal border. No nervous structures were found in the mineralized dentin of the root. Nervous structures which seemed to have no connection with the odontoblastic processes were frequently observed in the predentin of the root. Signs of degeneration of the nervous structures of the predentin of the root was also a common finding. The observation that the intradentinal nerves were confined to the predentin and the most pulpal part of the dentin supports the theory that surface stimulation on dentin has an indirect effect on the nerves activated by movements in the liquid of the dentinal tubules.

Adolescent↗
PubMed1984

Cell sizes and apposition of dental hard tissues in rats.

The daily apposition of the enamel and dentin and the sizes of ameloblasts and odontoblasts in the first upper molar of 2- to 9-day-old and of 12-day-old rats were examined by light microscopy of freeze-dried sections. The formation of enamel in the first molar started at the age of 2 days and was completed in most of the analyzed areas at the age of 9 days. On each day the enamel on the mesial sides of the cusps was about twice as thick as on the distal sides. The differences in thickness of dentin between the mesial and distal sides of the cusps were not as marked as was seen for the enamel. However, the rapid formation of dentin seemed to continue longer on the mesial sides than on the distal sides. The height of the ameloblasts and odontoblasts showed similar differences between the mesial and distal sides as was seen in the formation of enamel and dentin. In addition, these cells showed a gradual increase and decrease in height during the observation period, with a maximal height in the analyzed area at the age of 4-6 days.

Aging↗
PubMed1994

A method for light microscopy examination of cellular and structural interrelations in undemineralized tooth specimens.

This study examines ameloblasts and odontoblasts in relation to mineralizing enamel and dentin in thin undemineralized tooth sections from unerupted and partly erupted human third molars. The material comprised 12 freshly removed third molars. After fixation for 24 h the specimens were dehydrated and embedded in hydroxyethylmethacrylate. Undemineralized sections 10-15 microns thick were prepared with a cutting-grinding system, and radiomicrographs were taken. Postsecretory ameloblasts were seen in different morphologic stages ranging from ruffle- and smooth-ended ameloblasts to cuboidal and squamous cells adhering to incomplete and fully mineralized enamel. The former occurred in the most coronal tooth part, whereas the latter were seen cervically. It was not possible to identify systematic modulation cycles as seen in postsecretory rat incisor ameloblasts. The well-defined subodontoblastic region with cell-free and cell-rich layers was established before tooth eruption. The function of the subodontoblastic region is not fully understood, but our findings suggest that the establishment of the region plays a role in maintaining the specific odontoblast phenotype in the coronal region possibly linked to progressive dentin mineralization.

Ameloblasts↗
PubMed1992

Effects of ascorbate-deficiency on collagen secretion and resorption in cultured mouse incisor germs.

The effects of ascorbic acid deficiency on mouse incisors, grown in vitro, has been investigated at the histological and cytological levels. In this model, continuously growing mouse incisors are characterized by the existence of different type of predentin-dentin matrix on its lingual (root-analogue) and labial (crown-analogue) surface and the absence of enamel on the lingual surface. Our observations indicated that ascorbate-deficiency affected the behavior of mouse tooth germs in vitro: odontoblast differentiation was disturbed and morphological evidence for odontoblast-mediated collagen resorption were observed. An abnormal amorphous predentin-dentin matrix existed and the basement membrane was prematurely disrupted. The dentin mineralization, as well as functional differentiation of ameloblasts were strongly hampered. Chronic deficiency led to disorganization of the dental tissues.

Absorption↗
PubMed1995

Molecular analysis of rat dentin sialoprotein.

Dentin sialoprotein (DSP) is a noncollagenous protein originally isolated from rat dentin. Because it is made by odontoblasts that are actively synthesizing dentin. DSP may play an important role in dentinogenesis. We have isolated a full length DSP cDNA from a rat odontoblast/dental pulp cDNA library (Ritchie et al. [1994] J. Biol. Chem. 269:3698-3702) which codes for a 17 residue signal peptide and a 366 residue, 53 kDa mature protein. In situ hybridization revealed DSP mRNA expression by odontoblasts, but no other cells, in jaws from newborn rat. Northern analysis of various rat tissues demonstrated the presence of DSP transcripts in newborn tooth germs and 21 day old rat incisors. Moreover, multiple transcripts of 4.6 kb and 1.5 kb were found in these two tissues. To better understand the origin of these DSP mRNA multiple transcripts, we have isolated two rat genomic clones. Digestion of each clone with EcoRI followed by Southern analysis revealed that DSP cDNA hybridized to a 4 kb fragment in a lambda dash clone and to a 6 kb fragment in a cosmid clone. Since DSP cDNA hybridized to a 6 kb EcoRI fragment and a 4 kb EcoRI fragment obtained from a rat liver genomic cDNA digested with EcoRI, the multiple DSP mRNA transcripts are most likely derived from two related DSP genes which coexist in the rat genome.

Animals↗