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PubMed2003

[In situ hybridization analysis of USF1 mRNA expression in odontoblasts].

OBJECTIVE: To detect and verify USF1 mRNA expression in odontoblasts. METHODS: T-USF1 clone prepared previously was used as template and the desired USF1 cDNA segment was amplified by PCR with specific primers. The segment was labeled with digoxin as a probe and in situ hybridization was performed on the mounting of odontoblasts. RESULTS: Evidently positive staining was shown in the cytoplasm of odontoblasts. CONCLUSION: We verified the expression of USF1 mRNA in odontoblasts for the first time and provided evidence for further research.

DNA-Binding Proteins↗
PubMed1992

Immediate physiological response of odontoblasts.

The normal structure and function of the odontoblast cell layer is often perturbed by a variety of pathological processes as well as by the restorative procedures and materials required to treat them. It is well accepted and documented that a number of acute histological changes may take place under these circumstances resulting in the loss of integrity of the odontoblast cell layer. To date, our understanding of the immediate physiological response of the odontoblast to pathological processes or iatrogenic trauma remains limited. This paper reviews: first, the evidence for and against the existence of physiological barrier between the distal segments of odontoblast cell bodies; second, the alteration of this physiological barrier following routine restorative procedures; third, the role junctional complexes may play in this barrier function, and finally, the role that dental innervation, both afferent and efferent, may play in influencing and regulating the response of the dental pulp to external stimuli.

Animals↗
PubMed1992

[Scanning electron microscopic studies of the odontoblasts and the pulpodentinal border in domestic sheep (O. ammon aries Linnaeus, 1758)].

In order to investigate odontoblasts and predentin surfaces using SEM techniques, teeth of sheep with one or several roots were subjected to critical point drying. The odontoblasts of the root pulp are distinguished in their shape and arrangement pattern from those in the crown pulp. They regularly are detaching only one process of Tomes, which is extending up to the border between dentin and enamel and which shows a dendritic ramification in the dentin next to the enamel. The distal cell portions of the odontoblasts are joined together by a system of terminal bars. The collagen structures observed between the odontoblasts and predentin are considered to be von Korff's fibres as found in man.

Animals↗
PubMed2006

[Primary culture and identification of mouse odontoblast-like cells].

PURPOSE: To culture primary mouse odontoblast and to provide a base for study on inducing ES cells to odontoblast. METHODS: Lower incisor germs were removed from 1-week-old mouse. The dental papillae were isolated in microscope, and the dental papillae cells were dispersed using 0.25% collagenase and 0.25% trypsin. The cell clones, which had similar morphology to odontoblasts, were selected for further culturing. The primary cultured cells were identified by light and electron microscopes and mRNA expression of mouse dentin sialophoprotein. RESULTS: The cultured cells had the same morphology and ultrastructure. They were rich in Golgi's complex, ribosome and rough endoplasmic reticulum. These cells expressed DSPP at mRNA levels. CONCLUSION: The cultured cells were mouse odontoblast-like cells. The method could be used for the study of odontal cells in vitro.

Animals↗
PubMed1985

The extent of the human odontoblast process as determined by transmission electron microscopy: the hypothesis of a retractable suspensor system.

After fixation of fully formed human permanent teeth in liquid nitrogen the extent of the odontoblast process has been studied in transmission electron microscopy. The odontoblast process, limited by a trilaminar plasma membrane, was found just under the dentine-enamel junction. In cross section, the cytoplasm contained a granular mass with light and/or dense core granules. Bare unmyelinated nerve-like fibrils were seen in close connection with the odontoblast process. In the periodontoblastic space non calcified collagen fibrils were occasionally present. Cytoplasmic globules and granules limited by a trilaminar membrane, with occasional myelinic figures were also noted in the peripheral tubular lumens. The hypothesis of a retractable suspensor system is advanced to explain why in normal fixation conditions the odontoblast processes associated with nerve fibrils have not been observed in the outer layers of dentine.

Adolescent↗
PubMed1985

Intercellular junctions between human odontoblasts. A freeze-fracture study after demineralization.

Intercellular junctions in the odontoblastic layer have been studied with a freeze-fracture technique. Children's tooth germs were fixed, sliced and demineralized. Samples of the pulpodentinal border were routinely prepared for freeze-fracture. Three kinds of intercellular junctions were detected between human odontoblast cell bodies: gap junctions, desmosomes and tight junctions. Numerous gap junctions are responsible for intercellular communication at different levels of the cell bodies. Focal tight junctions, parallel to the axis of the cell, and desmosomes are sites of cell-to-cell adhesion between lateral plasma membranes. At the distal end of the cell bodies, junctional complexes consist of zonular tight junctions and gap junctions. These zonular tight junctions, never before described between odontoblasts, contribute to the pseudo-epithelial organization of the odontoblastic layer. They constitute a predentin-pulp barrier, the permeability of which must be studied to establish their role in relation to dentin formation.

Adolescent↗
PubMed1980

[Ultrastructure of individual odontoblast cilia].

Odontoblasts of teeth anlagen in inbred white rat fetuses were studied electron microscopically. On the lateral surface of some odontoblasts isolated cilia were discovered, directed, as a rule, towards intercellular spaces. Cilial trunk is covered with the odontoblastic cytomembrane and in the area of the basal body the membrane is forming a sack-like enlargement. Either 9 or 8 pairs of peripheral fibres are seen in the transversal sections of cilia, while the central pair of fibrils is absent. The basal body is a cylinder formed by 9 fibrillar triplets. A basal root runs from the basal body. It is suggested that the isolated cilia of odontoblasts are not rudimentary formations, but performed certain sensory function.

Animals↗
PubMed1980

Tunicamycin inhibits mouse tooth morphogenesis and odontoblast differentiation in vitro.

Tunicamycin (TM), an antibiotic that selectively inhibits dolichol-mediated protein glycosylation, inhibited morphogenesis and differentiation of odontoblasts in the molar tooth germ in vitro. These effects of TM are reversible and dose-dependent, and in advanced teeth the effect of TM was not complete unless the basement membrane was removed prior to culture. TM did not prevent secretion of predentin or enamel when added to the cultures after initiation of predentin secretion. TM dramatically inhibited protein glycosylation and the accumulation of labeled proteoglycans and glycoproteins in the basement membrane. Our previous studies indicated that odontoblast differentiation is triggered by an interaction between the basement membrane and mesenchymal cells. We suggest that TM inhibits odontoblast differentiation by causing alterations in the basement membrane which prevent the necessary cell-matrix interaction required for odontoblast differentiation.

Animals↗
PubMed1994

In vitro study of differentiating odontoblasts in isolated rat incisor dental papillae.

The dental papillae isolated from rat incisor were examined morphologically and autoradiographically in order to investigate progressive odontoblast differentiation in vitro. Four to eight days after incubation, the preodontoblasts which were labelled with 3H-thymidine became elongated, polarized, odontoblast-like cells with long cytoplasmic processes. They produced an 3H-proline labelled extracellular matrix on the substrate with which the dental papillae were coated. In addition, the odontoblasts located on the initially formed predentin maintained their ordinary shape as elongated cell bodies with long cytoplasmic processes and polarity fo the organelles during the term of culture. The results indicate that the surface of the agar gel substrate may be a critical requirement for odontoblast differentiation, development, and maturation in the absence of both the basement membrane and the enamel epithelium in the culture system used in this study.

Agar↗
PubMed1975

Cellular renewal in the enamel organ and the odontoblast layer of the rat incisor as followed by radioautography using 3H-thymidine.

Renewal of the cell populations of the incisor was studied in 100 gm male rats injected with a single dose of 3H-thymidine and sacrificed at various times from one hour to 32 days after injection. Radioautographs showed that a cohort of labeled cells within the enamel organ, odontoblast layer, and pulp was carried passively with the erupting incisor from the apical end towards the gingival margin where the life cycle of these cells was terminated. Labeled cells in the upper and lower incisor, although traversing different absolute lengths, were found in approximately the same functional stage of their life cycle at similar times after the injection. Thus, by one and on-half days labeled ameloblasts began inner enamel secretion and, by eight days (upper) or nine days (lower), complement outer enamel secretion. By 32 days labeled ameloblasts had traversed the entire enamel maturation zone and were located at the gingival margin. Labeled odontoblasts followed closely the movement of labeled ameloblasts. The mean rate of ameloblast migration was 567 mum/day on the upper incisor and 651 mim/day on the lower. For the odontoblasts this rate was 55 mum/day (upper) and 631 mum/day (lower). Finally, it was found that as the rat age, the duration of the life cycle for epithelial and pulp cell populations of the incisor increased because of growth within the lonitudinal axis of the tooth. It was concluded that the apical end of the incisor literally "grows backward" in the bony socket, and hence, the duration of the life cycle becomes greater simply because it takes cells longer to physically reach the gingival margin.

Ameloblasts↗
PubMed1992

Human odontoblasts contain S-100 protein-like immunoreactivity.

S-100 protein is a group of three closely related isoforms (S-100ao, S-100a, and S-100b). This protein was first described as unique to the nervous system but it has also been identified subsequently in a variety of cell types of neuroectodermal (i.e., melanocytes, glial cells) and non-neuroectodermal origin (i.e., Langerhans cells, adipocytes, chondrocytes). In the present investigation the presence of S-100 protein was studied in human odontoblasts using a specific polyclonal antibody directed against S-100 protein in immunoperoxidase labelling experiments. The S-100 protein was detected in the cytoplasm of odontoblasts. This result suggests that S-100 protein can play a role in odontoblast functions.

Antibodies↗
PubMed2004

In vitro response of osteoblast-like and odontoblast-like cells to unsubstituted and substituted apatites.

Different types of calcium phosphate compounds [calcium-deficient apatite (CDA); beta-tricalcium phosphate (beta-TCP); biphasic calcium phosphate (BCP)] are commercially available for medical and dental applications as bone substitute materials. Most of the reported in vitro studies on cell-material interactions have used osteoblast-like cells. The purpose of this study was to investigate the in vitro response of osteoblast-like (MC3T3-E1) and odontoblast-like (MDPC23) cells on unsubstituted (HA) and substituted (F-substituted) apatites. MC3T3-E1 and MDPC23 were cultured in alpha-modified medium containing 10% fetal bovine serum, ascorbic acid (50 microg/mL) and beta-glycerophosphate (2 mM). The cells were seeded on pellets made from HA, and FAp (with low, medium, and high F concentrations). Cell morphology was observed after 7 and 14 days using scanning electron microscopy (SEM). Cell attachment and differentiation were determined from the DNA content, alkaline phosphatase (ALP) activity, and total collagen content. Pellet surface composition was characterized by using Fourier Transform infrared spectroscopy. MC3T3-E1 and MDPC23 cells on HA were normal in shape and in fusion but not on FAp. Results of this study showed that the pattern of cell proliferation of osteoblast-like cells was different from that of the odontoblast-like cells. This study suggests that cell morphology, fusion, and proliferation on biomaterial surfaces depend on cell type (osteoblast-like vs odontoblast-like cell) and biomaterial composition (unsubstituted vs substituted F-apatites).

Alkaline Phosphatase↗
PubMed2004

Altered localization of Cav1.2 (L-type) calcium channels in nerve fibers, Schwann cells, odontoblasts, and fibroblasts of tooth pulp after tooth injury.

We have determined the localization of Cav1.2 (L-Type) Ca2+ channels in the cells and nerve fibers in molars of normal or injured rats. We observed high levels of immunostaining of L-type Ca2+ channels in odontoblast cell bodies and their processes, in fibroblast cell bodies and in Schwann cells. Many Cav1.2-containing unmyelinated and myelinated axons were also present in root nerves and proximal branches in coronal pulp, but were usually missing from nerve fibers in dentin. Labeling in the larger fibers was present along the axonal membrane, localized in axonal vesicles, and in nodal regions. After focal tooth injury, there is a marked loss of Cav1.2 channels in injured teeth. Immunostaining of Cav1.2 channels was lost selectively in nerve fibers and local cells of the tooth pulp within 10 min of the lesion, without loss of other Cav channel or pulpal labels. By 60 min, Cav1.2 channels in odontoblasts were detected again but at levels below controls, whereas fibroblasts were labeled well above control levels, similar to upregulation of Cav1.2 channels in astrocytes after injury. By 3 days after the injury, Cav1.2 channels were again detected in nerve fibers and immunostaining of fibroblasts and odontoblasts had returned to control levels. These findings provide new insight into the localization of Cav1.2 channels in dental pulp and sensory fibers, and demonstrate unexpected plasticity of channel distribution in response to nerve injury.

Animals↗
PubMed1988

The effect of colchicine on protein secretion by differentiating odontoblasts and ameloblasts in the hamster tooth in vitro as shown by radioautography with 3H-proline.

We have examined radioautographically the protein synthetic and secretory activity of differentiating odontoblasts and ameloblasts, exposed for 9 h in vitro to various concentrations of colchicine in the presence of 3H-proline. Colchicine impairs the cytodifferentiation of the dental epithelium into ameloblasts and of the dental mesenchyme into odontoblasts; the effects depend on the dose. However, dental epithelial cells are more sensitive to the drug than dental mesenchymal cells. In stages prior to odontoblast differentiation, colchicine enhances the number of radioautographic grains over the dental epithelium without changing the grain counts over the dental basement membrane area. This suggests that in vitro the dental epithelium synthesizes and secretes proline-containing components that are not constituents of the dental basement membrane. Also, during the subsequent stages of ameloblast differentiation colchicine increases the number of radioautographic grains over the preameloblasts. The present data suggest that the primary in vitro target of colchicine is not the dental mesenchyme, but the dental epithelium. The data also indicate that differentiating ameloblasts synthesize and secrete significant amounts of proteins in vitro prior to the first deposition of enamel.

Ameloblasts↗
PubMed1988

Localization of 28 kDa calbindin in human odontoblasts.

The presence of 28 kDa calbindin in human odontoblasts was studied by use of specific antibodies raised against chick duodenal 28 kDa calbindin, in immunofluorescence, immuno-peroxidase, and electron-microscopic labelling experiments. The calbindin-like protein was detected mainly in the cytoplasm of odontoblast cell bodies, in their processes and occasionally in their nuclei. Correspondingly, at the ultrastructural level, immunoreactive material was associated with the cytosol, microfilaments and cilia. These findings suggest that human odontoblasts express a 28 kDa vitamin D-dependent calcium-binding protein, unlike those of rats and mice in which ameloblasts are the only cells immunoreactive for the protein.

Animals↗
PubMed1992

Calcium ion activity and pH in the odontoblast-predentin region: ion-selective microelectrode measurements.

Ca2+ ion activities and pH were measured in the odontoblast/predentin region of rat incisors by means of the microelectrode technique. In Ringer solution, the apparent resting membrane potential of odontoblasts was determined to be -24 +/- 4 mV (mean +/- SE), whereas the odontoblast intracellular pH was found to be 6.66 +/- 0.02. The values obtained are within the range of other cell types, as measured in similar incubating solutions. The pH in the extracellular predentin was higher than the intracellular pH, 7.00 +/- 0.02. The Ca2+ ion activity in predentin (pCa = 2.94 +/- 0.15) was found to be significantly (P less than 0.001) higher than that in the dental pulp extracellular fluid (pCa = 3.37 +/- 0.14). The 2-3 times higher calcium activity extracellularly in predentin, compared with the dental pulp, implies the existence of some ion-concentrating mechanism across the odontoblast layer in the direction of the mineralization front.

Animals↗
PubMed2002

Odontoblast processes in human dentin revealed by fluorescence labeling and transmission electron microscopy.

In the present undertaking, the distribution of odontoblast processes in human dentin was determined through the DiI carbocyanine dye fluorescent staining of the cell membrane, while F-actin was identified by rhodamine-phalloidin. Confocal laser scanning microscopy revealed intense labeling for both agents in inner dentin, while transmission electron microscopy (TEM) identified dentinal tubules including odontoblast processes in this area, each process being surrounded by a cell membrane and containing an abundance of filamentous structures. Electron-dense "lamina limitans" lined the dentinal tubules. Individual cell processes became narrower toward the middle area, and their overall numbers decreased as well under TEM. Labeling for F-actin was absent in both middle and outer dentin, while faint labeling for DiI was visible along the dentinal tubules as far as the dentino-enamel junction (DEJ), where it was also recognized within the tubules themselves. Under TEM, the dentinal tubules lined with electron-dense structures were, in fact, empty in the middle and outer dentin. Immediately below the DEJ, however, the tubules manifested dense concentrations of fine granular material. Our study, therefore, appears to suggest that odontoblast processes do not extend beyond the inner dentin of fully erupted human premolars.

Actins↗
PubMed1999

Terminal end of the human odontoblast process: a study using SEM and confocal microscopy.

Towards the middle of the eighteenth century, Tomes described the presence of membranous structures of cellular origin inside the dentinal tubules. Subsequent studies have been controversial regarding the terminal end of the odontoblasts. According to Fusayama, this cellular process reaches even the dentinal-enamel junction; others, such as Brännström, believed that this cellular process is present only in the inner third of the dentin. The aim of the present study was to determine the exact area up to which the terminal ends of the odontoblasts extend. With the aid of advanced confocal laser scanning microscopy (CLSM) cylindrical structures were demonstrated inside the tubules even in the absence of odontoblasts. This would confirm that the structures previously described as cellular processes can be identified with the lamina limitans of the peritubular dentin. High resolution field-emission scanning electron microscopy (FE-SEM) provided further evidence that tubular structures are only seen in the inner third of the dentin, towards the pulp.

Adult↗