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 19 recordsLinked to original sources
PubMed1999

A light microscopic study of odontoblastic and non-odontoblastic cells involved in tertiary dentinogenesis in well-defined cavitated carious lesions.

This study examines cellular and microradiographic findings in thin, undemineralized sections of 46 cavitated lesions, that were clinically well-defined with respect to lesion activity and estimated lesion age at extraction time. The progressive stages of surface breakdown ranged from enamel cavitation to larger dentine exposures classified as closed and open lesion environments. Measurements of the following parameters were performed using computerized image processing software: (a) the cytoplasm:nucleus ratio of primary odontoblast cells; (b) the cell:dentinal tubule ratio; (c) the adjacent predentine area (mum2), and (d) the cytoplasm: nucleus ratio of non-odontoblastic cells, and secondary odontoblast-like cells, where estimation of these cell types were based on structural criteria. In active enamel cavitated lesions, reduced odontoblast-predentine regions and indistinct subodontoblastic regions were noted. During initial dentine exposures, non-odontoblastic cells along the pulp-dentinal interface were observed as well. The first indication of tertiary dentine was seen in old lesions with exposed dentine. The tertiary dentine appeared more atubular in the closed/active lesions than in the open/slow-progressing lesions. The involved odontoblastic cells in tubular tertiary dentine in small open/slow-progressing lesions were comparable to the primary odontoblast cells, however, new dentinal tubules were also noted presenting a mixture between reactionary and reparative dentinogenesis. In close/active lesions non-primary odontoblastic cells were aligning the atubular tertiary dentine, whereas well-defined signs of secondary odontoblast-like cells were first seen in larger open lesions, producing tubular tertiary dentine. In conclusion, a strong relationship between external lesion environments and corresponding different formations of tertiary dentine was noted in advanced cavitated lesions. It is additionally suggested that the stimulation of tubular tertiary dentine could be a closely related reaction when an active lesion complex changes into a slower progressing lesion environment.

Adult↗
PubMed1998

A novel organ culture method to study the function of human odontoblasts in vitro: gelatinase expression by odontoblasts is differentially regulated by TGF-beta1.

Odontoblasts cannot be cultured by traditional cell culture methods, thus restricting in vitro studies. Here we present an organ culture method for human odonto-blasts that utilizes the pulp chamber as a culture crucible. Crowns of human third molars were dissected, pulp was gently removed, and the odontoblasts attached to and in the walls of the pulp chambers were cultured in serum-free OPTI-MEM medium, or DMEM/Ham's F12 medium containing 10% serum. Pulp tissues were cultured separately. Cell content and morphology were analyzed by SEM, and the removed pulps were examined by light microscopy. Proteins secreted into the medium with or without TGF-beta1 supplementation were metabolically labeled with [35S]methionine, and the total protein content was assessed by TCA precipitation and SDS-PAGE/fluorography. To assess the role of gelatinolytic enzymes on dentin matrix remodeling, we used enzymography to analyze the effect of TGF-beta1 on gelatinase A and B expression. SEM revealed odontoblasts in pulp chambers after 5 days of culture, with only few or no fibroblasts, and no alterations in the odontoblast cell morphology or differences between the cells cultured in serum-free and serum-containing media. Rarely were any odontoblasts present in pulp tissue. Radiolabeling revealed protein synthesis and secretion until day 6 in both the odontoblast and pulp cultures, with no marked differences between TGF-beta1-treated and control cultures. The level of gelatinase A remained constant up to 7 days, while gelatinase B expression was always low and decreased with time in culture. However, gelatinase B levels were markedly increased upon TGF-beta1 treatment of cells and remained high to day 7. The results suggest that this method provides a novel technique for the study of human odontoblasts in vitro and that odontoblasts can be cultured even in serum-free conditions.

Cells, Cultured↗
PubMed1984

Membrane junctions between odontoblasts and associated cells. A freeze-fracture study of the human odontoblastic cell layer with special reference to its nerve supply.

The relationship between odontoblasts and adjacent cell structures within the odontoblastic cell layer was analyzed by means of the freeze-fracturing technique. Two principal forms of interodontoblastic cell structures were found. The first was tubular or thread-like in appearance, having a general diameter around 0.1-1.0 micron. From morphological criteria these were believed to represent small, unmyelinated nerve fibers. The second type of cell structure found between odontoblasts was more irregular and heterogeneous in outline, and often lamellar or branched. These slender formations sometimes proved to constitute cellular projections from adjacent odontoblasts or neighboring, subodontoblastic fibroblasts. Both the nerve-like fibers and the irregular branched cells between the odontoblasts showed morphological contact areas with odontoblastic cell bodies. At these sites the intracellular distances were reduced, and characteristic gap junctional complexes occurred. Nerve ending specialization or membrane structures indicating the presence of chemical synapses on the odontoblastic cell surface were not observed.

Adolescent↗
PubMed1980

[Comparative studies of the microcirculation in the region of the odontoblastic layer of the teeth of rats. Part 1: Odontoblastic layer (author's transl)].

The article deals with the capillary system of odontoblasts in the rat incisor. Differences in capillary structure between molars and incisors are traced back to functional causes. The odontoblasts of developing molars and incisors possess a specially constructed capillary structure, in as much as the capillaries form a connected double arcade system above and below the odontoblasts. The author hypothesises that odontoblast activity in the rat is tied to this the odontoblasts. The author hypothesises that odontoblast activity in the rat is tied to this double capillary arcade. From the standpoint of germination and mineralisation, it seems important that the supplying capillaries are between the predentine and the odontoblasts.

Animals↗
PubMed1995

Temperature sensitive simian virus 40 large T antigen immortalization of murine odontoblast cell cultures: establishment of clonal odontoblast cell line.

During tooth formation instructive epithelial-mesenchymal interactions result in the cytodifferentiation of ectomesenchymal cells into odontoblasts which produce the dentin extracellular matrix (DECM). The purpose of our study was to establish a stable murine odontoblast cell line by immortalization of odontoblasts using retrovirus transfection. In order to accomplish this goal, we utilized a previously characterized odontoblast monolayer cell culture system supportive of odontoblast cytodifferentiation from dental papilla mesenchyme (DPM), expression and secretion of a DECM and dentin biomineralization. First mandibular molars from E-18 Swiss Webster mice were dissected, the DPM isolated, and pulp cells dissociated. Pulp cells (5 x 10(5)/well) were plated as monolayers and grown in alpha-MEM supplemented with 10% FCS, 100 units/ml penicillin and streptomycin, 50 micrograms/ml ascorbic acid. Cultures were maintained for 6 days at 37 degrees C in a humidified atmosphere of 95% air and 5% CO2, with media changes every two days. Immortalization was performed using a recombinant defective retrovirus containing the temperature sensitive SV-40 large T antigen cDNA and the neomycin (G418) resistance gene recovered from CRE packaging cells. Cultures were infected for 24 h with CRE conditioned medium containing 8 micrograms/ml of polybrene, the media was replaced with selective media containing 300 micrograms/ml of G418, and the cultures incubated at 33 degrees C for one month with media changes every 3-5 days. Neomycin resistant cells were cloned by serial dilution to single cells in 96-well culture plates and grown in selection medium at 33 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1998

Comparative analysis of mouse DSP and DPP expression in odontoblasts, preameloblasts, and experimentally induced odontoblast-like cells.

Dentin sialoprotein (DSP) and dentin phosphoproteins (DPP) are uniquely expressed by differentiating and fully differentiated mature odontoblasts. It is likely that DSP and DPP actively participate in the conversion of predentin to dentin. To compare the expression patterns of DPP and DSP, we constructed mouse cDNA probes. Northern analyses confirmed their specific expressions in tooth germ-derived RNA and showed that the probes reacted with similar or identical multiple transcripts. In situ hybridization indicated that DSP and DPP transcripts were uniquely detected and codistributed in developing mouse odontoblasts and preameloblasts. These data, as well as the adjacent positioning of the DSP and DPP coding sequences, suggest that common regulatory mechanisms control DSP and DPP expressions. Dental papillae cultures, in which odontoblast differentiation was experimentally induced with TGFbeta1 combined with heparin, were used to show that the two molecules are also coexpressed under in vitro conditions.

Ameloblasts↗
PubMed1985

Odontoblast differentiation and the formation of the odontoblast layer.

Origin, cell kinetics, and phenotypic aspects of odontoblast cell lineage are described. Epithelial-mesenchymal interactions regulate odontoblast differentiation. These interactions appear to be mediated by the extracellular matrix. Possible molecular mechanisms of cell-matrix interactions are discussed. Questions still unanswered are recommended for investigation.

Animals↗
PubMed1997

Expressions of c-jun and jun-B proto-oncogenes in odontoblasts during development of bovine tooth germs.

c-jun and jun-B genes are among the nuclear proto-oncogenes induced by growth factors such as the TGF-beta superfamily and play important roles in cell differentiation. These gene products enhance expressions of proteins including osteocalcin, alkaline phosphatase, and collagens. On the other hand, it is well-known that the TGF-beta superfamily affects odontoblast differentiation, and that differentiated odontoblasts express extracellular and membrane proteins as described above. However, there are few reports of factors that participate in the transcriptional regulation of odontoblasts. Especially, little is known about the expression of c-jun and jun-B genes. In this study, we focused on the examination of expressions of c-jun and jun-B genes in dental papillae of bovine tooth germs. Using in situ hybridization, we found that these genes were expressed only in the odontoblastic lineage, but not in other dental papilla cells. Levels of c-jun and jun-B mRNAs increased along the gradient of differentiation of odontoblasts. These levels of c-jun mRNAs were maintained in both young and mature odontoblasts. However, unlike the c-jun gene, expression of the jun-B gene became sparse in mature odontoblasts compared with young odontoblasts. For further analysis, Northern hybridization of total RNA extracted from differentiated odontoblasts was performed for the examination of levels of jun-B mRNAs, indicating that levels of jun-B mRNAs of mature odontoblasts were clearly less than those of young odontoblasts. These results suggest that c-jun and jun-B genes may participate in the transcriptional regulation of odontoblasts of bovine tooth germs, and may control the odontoblast phenotype. Furthermore, our results suggest that these genes can be markers of odontoblasts during dentinogenesis; especially, high expression of jun-B gene can be a marker of young odontoblasts that start to form the new dentin matrix.

Animals↗
PubMed1996

Structure and organization of odontoblasts.

Differentiation of odontoblasts involves cell-to-cell recognition, contact stabilization involving the formation of attachment specializations, cytoplasmic polarization, development of the protein synthetic and secretory apparatus, and the active transport of mineral ions. The secretory odontoblast is characterized by an extensive rough-surfaced endoplasmic reticulum, a highly developed Golgi complex, and the presence of specific secretion granules. Type I collagen, a major constituent of dentin matrix, appears to be secreted by the odontoblast into predentin at the proximal portion of the odontoblast process, the major cytoplasmic process extending from the odontoblast cell body into the dentin. The odontoblast process contains a rich network of microtubules and microfilaments. The proximal portion of the process is also a site of fluid-phase endocytosis. Adjacent odontoblasts are held together by numerous macula adherens junctions and a well-developed distal junctional complex adjacent to be predentin. Junctional strands of the occludens type have been observed to be a component of this junctional complex. Tracer studies employing horseradish peroxidase indicate that this junctional complex does not form a tight barrier to the diffusion of tissue fluid from the interodontoblast spaces into the predentin. Many well-developed gap junctions are formed between adjacent odontoblasts and between odontoblasts and the fibroblasts that make up the subodontoblastic layer. Ca-ATPase activity is demonstrated in the Golgi complex and mitochondrial cristae and along the distal plasma membranes of odontoblasts. ALPase activity is also intense along the entire odontoblast cell surface. The osmium tetroxide-pyroantimonate technique for calcium localization demonstrates prominent reaction precipitates in mitochondria of odontoblasts. Energy-dispersive x-ray microanalysis of anhydrously fixed and processed odontoblasts detected Ca and P peaks throughout the cytoplasm. A sulfur peak is noted in the distal cytoplasm of odontoblasts and in matrix vesicles. Together, these results demonstrate the complexity and variety of cell functions involved in dentinogenesis.

Animals↗
PubMed1996

Distribution and organization of peripheral capillaries in dental pulp and their relationship to odontoblasts.

BACKGROUND: Developmental and chronological changes in the peripheral capillaries of the dental pulp and their relationship to odontoblasts during dentin formation has not been sufficiently detailed. This study aims to elucidate the morphological changes of the peripheral capillaries in relation to the life cycle of odontoblasts. METHODS: Peripheral capillaries of the dental pulp were examined in the labial region of rat incisors and in the crown region of rat molars by using light, transmission, and scanning electron microscopy. RESULTS: Before the start of dentin formation, continuous capillaries formed a coarse vascular network under the odontoblast layer. With the start of dentin deposition, capillaries began to invade into the odontoblast layer and finally located close to the predentin, where they formed a dense vascular network consisting of fenestrated capillaries. In the incisors, dentin was formed actively even near the incisal tip, and fenestrated capillaries continued to locate in the odontoblast layer. In the molars, however, the activity of dentin deposition gradually decreased with the advance of dentin formation, and the fenestrated capillaries altered to continuous capillaries and withdrew from the predentin border to the odontoblastic-pulpal border shortly before the cessation of active dentin deposition. CONCLUSIONS: It is concluded that the changes in the peripheral capillaries are closely related to the secretory activity of the odontoblasts. To facilitate a rapid and sufficient supply of raw materials from the bloodstream to the calcifying front, peripheral capillaries first approach the odontoblasts, invade into the odontoblast layer close to the predentin with increases in density, and finally alter the endothelium from the continuous to the fenestrated type in compliance with the nutritional requirements of the odontoblasts, which lay down the dentin. When the activity of odontoblasts decreases, capillaries first alter the endothelium from the fenestrated to the continuous type, then retreat from the odontoblast layer, and finally locate below the odontoblast layer.

Animals↗
PubMed2003

Pulpal regeneration after cavity preparation, with special reference to close spatio-relationships between odontoblasts and immunocompetent cells.

The regeneration process of the odontoblast cell layer incident to tooth injury, especially its relationship with immunocompetent cells in pulp healing, has not been fully understood. The purpose of the present study was to clarify this relationship between odontoblasts and immunocompetent cells in the process of pulp regeneration following cavity preparation in rat molars by immunocytochemistry for heat shock protein (Hsp) 25 as well as class II major histocompatibility complex (MHC) molecules. In untreated control teeth, intense Hsp 25-immunoreactivity was found in the cell bodies of odontoblasts and their processes within the predentin, whereas class II MHC-positive cells were predominantly located beneath the odontoblast cell layer. Cavity preparation caused the destruction of the odontoblast layer to form an edematous lesion and the shift of class II MHC-positive cells with the injured odontoblasts toward the pulp core at the affected site. Some damaged odontoblasts without apparent cytoplasmic processes, round in profile, retained the immunoreactivity for Hsp25, suggesting the survival of a part of the odontoblasts against artificial external stimuli. Twelve hours after cavity preparation, numerous class II MHC-positive cells appeared along the pulp-dentin border and extended their processes deep into the exposed dentinal tubules. By postoperative 72 hours, newly differentiated odontoblasts with Hsp 25-immunoreactivity were arranged at the pulp-dentin border, but the class II MHC-positive cells moved from the pulp-dentin border to the subodontoblastic layer. These findings indicate that the time course of changes in the expression of Hsp 25-immunoreactivity reflects the regeneration process of odontoblasts. The functional roles of Hsp 25-positive odontoblasts and immunocompetent cells such as class II MHC-positive cells in the process of pulp regeneration after cavity preparation are discussed in conjunction with our previous experimental data.

Animals↗
PubMed1992

The relationship between odontoblasts and pulp capillaries in the process of enamel- and cementum-related dentin formation in rat incisors.

The relationship between odontoblasts and pulp capillaries in the process of dentinogenesis was studied in rat lower incisors, both on the labial and lingual sides, using light and transmission electron microscopy. The odontoblasts showed remarkable differences from the apical to the incisal end. Near the apical end of the tooth, "immature odontoblasts", which were thought to be involved in the formation of the mantle dentin, were arranged in a single layer, and continuous capillaries were located just beneath the odontoblasts. In the middle of the tooth, "mature odontoblasts" with highly developed cell organelles and notable processes formed a pseudostratified layer; fenestrated capillaries were found between these cells close to the predentin. The height of the odontoblast layer and the rate of dentin deposition on the labial (enamel-related) side was significantly greater than that on the lingual (cementum-related) side. Near the incisal end, cementum-related odontoblasts gradually decreased in height and number to become "post-odontoblasts" that produced atubular dentin; continuous capillaries were located subjacent to the post-odontoblasts. On the labial (enamel-related) side, however, odontoblasts retained their pseudostratification; fenestrated capillaries were still observed in the odontoblast layer. No atubular dentin was formed on the labial side.

Animals↗
PubMed1990

Ultrastructural changes in odontoblasts and pulp capillaries following cavity preparation in rat molars.

Responses of odontoblasts and pulp capillaries to cavity preparation were investigated in the upper first molar teeth of rats, using light and transmission electron microscopy. At 100 days of age, the blood vessels of the pulp formed a subodontoblastic network consisting of continuous capillaries at a short distance from the odontoblast layer. Cavity preparation caused the displacement of some odontoblasts into the dentinal tubules, while others were separated from the predentin by rapid inflammatory exudation after drilling. The subodontoblastic capillary network under the injured dentin was shifted inwards together with the separated odontoblasts. The endothelium of the shifted capillaries showed a remarkable increase of pinocytotic vesicles, an event thought to be closely related to the formation of the exudative lesion. By one day after cavity preparation, most of the damaged odontoblasts had degenerated. Many cells with high nucleus/cytoplasm (N/C) ratios and prominent nucleoli accumulated around the subodontoblastic capillaries, some of which had many endothelial fenestrae facing these cells. These cells were suggestive of newly differentiating odontoblasts receiving nutritional supply from the capillaries. Three days after cavity preparation, newly differentiating odontoblasts took the place of the degenerated odontoblasts. They began to produce reparative dentin by five days after cavity preparation. Capillaries were located beneath the newly differentiating odontoblasts, but endothelial fenestrae gradually decreased in number. During the active reparative dentin formation, capillaries remained closely beneath the new odontoblast layer. Although the rate of reparative dentin deposition was not significantly lower than that in the primary dentin formation, one could not recognize an invasion of capillaries into the odontoblast layer nor a remarkable increase of endothelial fenestrae, both of which are common in active primary dentin formation. The results suggest that the function of capillaries differs between primary and reparative dentin formation.

Animals↗
PubMed1985

Morphometric analysis of the nucleolus during the life cycle of human odontoblasts.

Developing first premolars were used as a model system to obtain information on the nucleolar structure of human odontoblasts at several stages of their life cycle. Four stages were defined by their location within the tooth: a) preodontoblasts were located at the growing tip of the root; b) secretory odontoblasts in the apical region; c) transitional odontoblasts in the middle region; and d) aged odontoblasts in the coronal region. Preodontoblasts have a small nucleolus (0.55 micron 2) with few strands of dense fibrillar material radiating from the fibrillar center. Secretory odontoblasts are characterized by a large (1.24 micron 2), irregular, and reticulated nucleolus. The fibrillogranular material, the largest component in all nucleoli, reaches maximal size at this stage (0.88 micron 2). Fibrillar centers occupy about the same area (0.1 micron 2) throughout the odontoblast's life cycle. As the formation of primary dentin is completed, the nucleolus of transitional odontoblasts is reduced in size (0.54 micron 2). Finally, the aged odontoblasts have a small, compact nucleolus (0.39 micron 2), with segregated components. Morphologic analysis and quantification of size and component areas of nucleoli obtained with an image analyzer indicated that secretory odontoblasts had the most active, and aged odontoblasts the least active, nucleolus.

Bicuspid↗
PubMed1994

Collagen fibrils in the odontoblast layer of the rat incisor by scanning electron microscopy using the maceration method.

BACKGROUND: There is not universal agreement on the existence of the extracellular pathway from the pulp along the odontoblast layer to the predentin. METHOD: To confirm this pathway, the architecture of collagen fibrils in the rat incisor dentin and pulp, especially in the odontoblast layer of the lateral (periodontal ligament) sides of the tooth, was demonstrated in the present investigation using scanning electron microscopy of the maceration method for collagen networks. RESULTS: Numerous collagen bundles were observed in the odontoblast layer in the mature odontoblast region which, except for the young odontoblast region, comprises the major portion of the incisor. The collagen bundles went from the pulp, through the odontoblast layer, and were woven into the collagen network of the predentin. The meshwork structure was composed of fine secondary fibrils among these collagen bundles. The surface of the predentin contained many oval-shaped holes which were surrounded by collagen fibrils. Fracturing the dentin longitudinally relative to the dentinal tubules revealed that the arrangement of the collagen fibrils at the surface of the tubules was either circular or oblique. In the young odontoblast region, i.e., the thin portion from the apical end of the incisor where the mineralization of the dentin does not occur and where the height of the odontoblasts was less than 30 microns, many thick bundles composed of thick collagen fibrils ran straight from the pulp to the predentin through the odontoblast layer and fanned out in the collagen network of the predentin. These thick bundles might correspond to the so-called "von Korff fibers." The distribution of collagen fibrils in the pulp was random except on the surface of the blood vessels where the fibrils comprised two sheets of collagen: the inner sheet which coursed longitudinally to the long axis of the vessel, and the outer sheet which ran transversely. CONCLUSION: It was considered that the fluid in the pulp could flow to the predentin along the collagen fibrils through the tight junction between the odontoblasts.

Animals↗
PubMed2001

Expression and localization of connexin 43 in rat incisor odontoblasts.

We have examined the expression and localization of connexin 43 (CX43) in rat incisor odontoblasts using reverse transcriptase polymerase chain reaction, in situ hybridization and immunohistochemistry. The CX43 gene was expressed in odontoblasts, and levels of gene expression increased throughout the course of development. In contrast, CX43 was down-regulated at an incisal segment. In situ hybridization analysis showed no positive signal for CX43 RNA in the cytoplasm of differentiating dental papilla cells, but faint positive signals for CX43 RNA were observed in early pre-odontoblasts. Those signals were more intense in young and in old odontoblasts, but were less in short odontoblasts. CX43 could not be detected in differentiating dental papilla cells or in early pre-odontoblasts by immunohistochemical localization, but a positive reaction was found in the late pre-odontoblast stage where predentin had been produced. The positivity gradually increased during odontoblast maturation, and was highest in the layer of old odontoblasts. These results indicate that odontoblasts that secrete actively dentin matrix components are tightly in contact with each other by gap junctions as suggested by the intense CX43.

Animals↗
PubMed2000

A substractive PCR-based cDNA library from human odontoblast cells: identification of novel genes expressed in tooth forming cells.

Odontoblasts are highly specialized cells aligned at the edge of the dental pulp. As a step towards understanding the complex mechanisms underlying their terminal differentiation, the gene expression pattern was examined in human cultured odontoblast cells. Suppression substractive hybridization (SSH) was used to establish a substracted cDNA library specific for human odontoblasts. For this purpose, cDNAs from human cultured fibroblastic pulp cells were substracted to cDNA from human cultured odontoblasts. The nucleotide sequence of 154 substracted cDNA clones was determined. We identified 130 preferentially expressed gene fragments in odontoblasts as compared with the fibroblastic pulp cells. Ten of them were already identified in odontoblasts such as DSPP, BSP, enamelysin and Col1A1. We confirmed their overexpression by RT-PCR on the cultured cells and in vivo by in situ hybridization on human molars. Another 64 clones corresponded to known genes. Among them, two clones were of particular interest: reelin, which was first detected in the brain and osteoadherin, which was first located in bone. Fifty-six clones were unknown genes even though 82% matched expressed sequence tags or genomic clones. A reverse Northern dot blot showed that 96% of them were overexpressed at different rates in cultured odontoblasts. These latest results indicate that there are still unknown genes that are associated with the control of the odontoblast phenotype. Thus, cloning of odontoblast differentiation-associated genes not only opens up new methods of elucidating the normal development but also the recruitment of odontoblasts when required to initiate repair of dentin.

Base Sequence↗