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PubMed1992

Effects of dentin proteins, transforming growth factor beta 1 (TGF beta 1) and bone morphogenetic protein 2 (BMP2) on the differentiation of odontoblast in vitro.

We have studied the effects of dentin proteins, of Transforming Growth Factor beta 1 (TGF beta 1) and Bone Morphogenetic Protein (BMP2) on the differentiation of odontoblasts in vitro. The total EDTA-soluble fraction of dentin proteins, prepared from rabbit incisors was further separated by chromatography on DEAE-Cellulose and heparin-agarose columns. While the total EDTA-soluble fraction of dentin had no effect on cultured dental papillae, fractions retained on both columns were able to initiate functional differentiation of preodontoblasts of isolated day-17 first lower mouse molar dental papillae cultured in vitro. TGF beta 1 and BMP2, both stimulated the matrix secretion by dental papillae cells. TGF beta 1 and BMP2, combined with the inactive total EDTA-soluble fraction, stimulated odontoblast differentiation. An active fraction retained on DEAE-Cellulose completely lost the inductive activity after incubation with a neutralizing anti-TGF beta antibody. These results demonstrate that a TGF beta-like molecule present in dentin could interact with some component which acts as a modulator of its activity on the initiation of the cytological and functional differentiation of odontoblasts.

Animals↗
PubMed1992

The isolation and primary culture of putative human root odontoblasts.

The use of procedures adapted from a routinely successful method of culturing bovine bone has led to the first system for the study of dentinogenesis in vitro. Two types of cells have been grown from pulp obtained from the growing root tips of impacted third molars extracted from 14- to 19-years olds: (1) epithelial-like cells that are probably derived from fragments of the epithelial root sheath and (2) odontoblast-like cells. The cultured epithelial-like cells grow out in distinctive rounded plaques while the odontoblast-like cells are tethered to and/or grow on top of the epithelial-like cells. The odontoblast-like cells produce mineralized matrix by 10 days when cultured on a defined mineralization formula containing conditioned medium obtained from fetal bovine bone cell cultures. Growth factors in this conditioned medium are important to cell proliferation and growth and to the synthesis of mineralized matrix. Sequential enzyme digestion in dispase and dispase/collagenase in serum-free Dulbecco's Modified Eagle's Medium is essential to obtaining adequate cell yields from the apical 3-5 mm of the developing root. Reduction of the number of fibroblasts by treating cultures with dispase in Tyrode's solution midway through the initial growth period enhances the purity of these cell cultures.

Adolescent↗
PubMed2004

[The basic characters and research advancements of odontoblasts].

As the main components of dental pulp cells,the odontoblasts were responsible for the formation and maintenance of dentin during the development and mature age of teeth. Presently the studies were mostly based on the two-dimensional vitro cultured technique,but with the developing research of pulp tissue, three-dimensional vitro cultured technique will be the study hotspot in future. The author retrospected the investigation about the odontoblasts these years and mostly expatiated the morphology,ultrastructure,function and characters of protein expression about the odontoblasts,including the research advancements and research aspects in future.

Dentin↗
PubMed1989

[Scanning electron microscopic studies of the para-odontoblast region of juvenile permanent teeth].

40 erupted premolar teeth from 9-14 year old patients requiring orthodontic treatment, were prepared for a study of the dentin-predentin-pulpal area with the scanning electron microscope. The odontoblast process has been found in all specimen extending through the predentin, inner dentin and middle layer of dentin. In the coronal pulp the odontoblast cell bodies were arranged closely together with granulated surfaces, surrounded by fibrillar structures and membrane junctions. As a rule a lot of spherical aggregates of crystals were present between the odontoblasts and the predentin surface.

Adolescent↗
PubMed1995

From serum to the mineral phase. The role of the odontoblast in calcium transport and mineral formation.

Dentin may be considered as a calcified connective tissue and is in its composition as well as in its mode of formation closely related to bone. Dentin is formed by two simultaneous processes in which the odontoblasts are instrumental: the formation of the proteinaceous dentin matrix, and mineral crystal formation in this matrix. As part of this, the odontoblasts actively transport Ca2+ ions towards the site of mineral formation. The cells maintain a delicate intracellular Ca2+ ion balance by the concerted action of transmembraneous transport mechanisms, including Ca-ATPase, Na+/Ca2+ exchangers and calcium channels of the L-type, and possibly intracellular Ca(2+)-binding proteins. The net effect of this is a maintenance of a cytoplasmic sub-micromolar Ca2+ activity and an extracellular accumulation of Ca2+ ions at the mineralization front. In addition to the major matrix constituent, collagen, non-collagenous macromolecules, such as dentin phosphoprotein (phosphophoryn), dentin sialoprotein, and proteoglycan, are synthesized by the odontoblasts and deposited in the matrix. Such polyanionic macromolecules are presumably responsible for the extracellular induction of hydroxyapatite crystals, but may also function to inhibit mineral growth and to regulate crystal size. Accordingly, it can be concluded that dentinogenesis comprises an interplay between several factors in the tissue, cellular as well as extracellular.

Animals↗
PubMed1995

Odontoblast differentiation.

Odontoblasts are post-mitotic, neural crest-derived, cells which overtly differentiate according to tooth specific temporo-spatial patterns and secrete predentin-dentin components. Neither the timing nor the molecular mechanisms of their specification are known and the problem of their patterning in the developing jaws is far from being solved. On the other hand, some significative strides were made concerning the control of their terminal differentiation. Fibronectin interacting with a 165 kDa, non integrin, membrane protein intervenes in the cytoskeletal reorganization involved in odontoblast polarization and their terminal differentiation can be triggered in vitro by immobilized members of the TGF beta family. Histological aspects and the transcriptional phenotypes (transcripts of TGF beta s, BMPs, msxs, IGF1, fibronectin, osteonectin, bone sialoprotein genes) are very similar in vivo and in vitro. In vivo members of the TGF beta super family secreted by preameloblasts, trapped and activated by basement membrane associated components, might initiate odontoblast terminal differentiation.

Animals↗
PubMed1976

The extent of the odontoblast process in the cat.

Earlier work has shown that in the dentine of cats perfused with aldehyde fixatives for short periods the odontoblast process seems to be limited to inner dentine. This could possibly have been an artefact due either to inadequate penetration of the fixative or shrinkage of the cells. Experiments prolonging the duration of the fixation and raising the concentration of the fixatives, examining dentine from regions and species where it is narrow and more accessible to fixatives, and looking at dentine fixed by immersion both in situ and after excision, all showed the process to be limited to inner dentine. Measruing glutaraldehyde penetration through model dentine and also through dentine in the perfused animal showed that this fixative penetrates the dentine well. Variations in fixative osmotic pressure, while having a profound effect on cells and processes in vitro and causing changes in cell shape in the intact animal, do not neasurably alter the extent of the odontoblast process. The conclusion is that the odontoblast process in the cat is limited to the pulpal half of the dentine. As a consequence, no cellular mechanism can be involved in the transmission of stimuli across the outer dentine.

Acrolein↗
PubMed1998

[Immunocytochemistry of proteoglycan in dentin and odontoblasts].

To clarify the distribution of proteoglycan (PG) and matrix metalloproteinase-3 (MMP-3) in the molar tooth germ dentin of rats, immunohistochemical investigation was performed using a antibody 2-B-6 specific for chondroitin 4 sulfate (Ch4-S) and dermatan sulfate (DS) of PG, antibody 3-B-3 specific for chondroitin 6 sulfate (Ch6-S) and chondroitin (Ch) of PG and anti-human-MMP3 antibody. 2-B-6 reacted with the predentin and dentinal tubules. However, there were no reactions around the calcification front or in the calcified dentin matrix other than the dentinal tubules. 3-B-3 and anti-MMP3 antibodies reacted with only the predentin. These results showed that PG containing Ch4-S and DS was present in the dentinal tubules, while PG containing Ch4-S, DS, Ch6-S and Ch as well as MMP-3 was present in the predentin. It is suggested that PG of the predentin is degraded by MMP-3 at the calcification front. In undecalcified sections, the reaction of the dentinal tubules with 2-B-6 was localized in electron-dense sites corresponding to the peritubular dentin, suggesting that PG at this site binds to hydroxyapatite. Furthermore, in odontoblasts, the localization of 2-B-6 was noted in secretory granules distributed in the Golgi region and the odontoblastic process. This suggests that PG is transported from the Golgi region to the odontoblastic process in the form of secretory granules. Immunoreactive secretory granules were also noted in the cellular process of the calcified dentin. PG of the peritubular dentin may be secreted by these secretory granules in the process.

Animals↗
PubMed1996

Endocytotic functions of ameloblasts and odontoblasts: immunocytochemical and tracer studies on the uptake of plasma proteins.

BACKGROUND: Biochemical, (immuno)cytochemical, and radioautographic data accumulated over several years have lead to the view that ameloblasts carry out both secretory and degradative functions throughout amelogenesis. Whereas it has been assumed that maturation stage ameloblasts endocytose aged enamel proteins from the enamel layer, the origin of the newly formed ones detected in the endosomal/lysosomal compartment of ameloblasts from all stages remains to be elucidated. One possible source is from secretory products released ectopically along basolateral surfaces. METHODS: To test this hypothesis, we have investigated, using colloidal gold immunocytochemistry, whether plasma proteins (albumin and alpha 2HS-glycoprotein) found in the interstitial fluid are endocytosed by rat incisor ameloblasts and other cells from hard and soft tissues. Rat albumin, tagged with dinitrophenol, was injected intravenously to trace the movement of this protein. RESULTS: Plasma proteins were immunodetected along the baso-lateral surfaces and in multivesicular bodies of ameloblasts where enamel proteins were also found. By 2 hours following intravenous administration of dinitrophenylated albumin, the tracer had left the blood and diffused into the enamel organ and between odontoblasts and osteoblasts. The tracer was also found in multivesicular bodies of all cells examined. CONCLUSIONS: The uptake of albumin by many different cell types suggests that this process is not restricted to ameloblasts and likely occurs in a nonselective manner. Hence, baso-lateral uptake in ameloblasts may play a role not only in the continuous removal of plasma proteins leaking from the blood, but also of enamel proteins 'dumped' laterally between these cells. Likewise, odontoblasts may use the same mechanism to internalize some of the plasma proteins and any enamel protein that diffuse toward them.

Albumins↗
PubMed1976

The binding of calcium within the Golgi saccules of the rat odontoblast.

Odontoblasts of developing rat molar teeth were treated with OsO4-pyroantimonate to ascertain the localization of calcium. In addition, some tooth germs were incubated in solutions which were intended to allow for the escape of diffusible ions prior to fixation in OsO4-pyroantimonate. In tissues treated directly with OsO4-pyroantimonate, antimonate reaction product was found chiefly in abacus bodies and secretory granules of the Golgi region and in secretory granules in the distal pole of the cell. Lesser amounts of reaction product were found in the extracellular space, mitochondria, nucleus and generally throughout the cell. Tissues pre treated to allow for the escape of diffusible ions showed reaction product, identified as containing calcium, only in the abacus bodies and secretory granules. These results are considered to reflect the binding of calcium within the Golgi apparatus of the odontoblast. Moreover, since it has been shown by others that the abacus bodies and secretory granules contain collagen precursor, it is suggested that the collagen precursor is being seeded with calcium within the Golgi apparatus and that this intracellular calcium binding will play a role in facilitating the major wave of extracellular mineralization of the dentin which is to follow.

Animals↗
PubMed1976

Ultrastructural localisation of proteoglycans in the odontoblast-predentin region of rat incisor.

The localization of proteoglycans in the predentin of the rat incisor was investigated by ultrastructural histochemistry. Ruthenium red stained the cell coat of the odontoblasts as well as intracellular vesicles. There was also a staining of the extracellular matrix, but not of collagen fibers in the predentin. Treatment with the enzyme hyaluronidase prior to staining with ruthenium red abolished the staining of the vesicles and the extracellular matrix but not that of the cell coat. Bismuth nitrate and phosphotungstic acid gave similar staining of odontoblast vesicles and extracellular matrix. It is likely that the stained structures contain proteoglycans. The importance of these proteoglycans and their ultrastructural localization are discussed in relation to intracellular transport and the calcification process.

Animals↗
PubMed1995

Cultured incisors display major modifications in basal lamina deposition without further effect on odontoblast differentiation.

Matrix-mediated epithelio-mesenchymal interactions play a crucial role in the control of dental cytodifferentiations. Ultrastructural observation of the epithelio-mesenchymal junction in cultured embryonic mouse molars showed discrete zones with duplicated or multilayered basal laminae. The use of synthetic peptides demonstrated that the process was RGD*-independent, did not involve the YIGSR* sequence present on laminin and could occur spontaneously. Cultured incisors showed a similar but much more dramatic multiplication of the basal laminae. Furthermore, the deposition of multilayered basal laminae was specific for the labial aspect of the tooth and could be detected after 6 h of culture. Despite these alterations, preodontoblasts differentiated and gradients of differentiation were maintained, suggesting that among basement membrane constituents, the basal lamina itself does not play a critical role. More important is the inner dental epithelium which may still control odontoblast differentiation by means of diffusible molecules able to reach surface receptors expressed by preodontoblasts or matrix receptors underlying the basal lamina. Gradients of odontoblast differentiation could result from a progressive acquisition of competence by preodontoblasts.

Amino Acid Sequence↗
PubMed1991

Co-distribution of annexin VI and actin in secretory ameloblasts and odontoblasts of rat incisor.

Annexin VI and actin were detected by immunoblot analysis in the enamel- and dentin-related portions of dental tissues. Annexin VI was found mainly in the particulate fraction whereas actin was detected in both the soluble and particulate fractions. By immunoelectron microscopy, annexin VI antibodies conjugated with colloidal gold were seen to label the mitochondria, the cytosol and the nucleus of secretory ameloblasts and odontoblasts of rat incisor. In the processes of these cells, the plasmalemmal undercoat was labeled. Anti-actin antibodies labeled the desmosome-like junctions, the cytosol, and the mitochondria of the cell bodies. Extensive labeling was seen at the periphery of the Tomes' processes and odontoblast processes. These results suggest that annexin VI may play a role in Ca2(+)-regulation in the cell bodies, especially as a calcium receptor protein in the mitochondria. Moreover, annexin VI and actin seem to be co-distributed in secretory processes. Thus, these proteins might be both involved in exocytotic and endocytotic events.

Actins↗
PubMed1998

Histotomography of the odontoblast processes at the dentine-enamel junction of permanent healthy human teeth in the confocal laser scanning microscope.

The translucency of teeth allows the non-destructive subsurface visualisation of their microstructure by confocal laser scanning microscopy (CLSM) at a level of about 150 microns below the surface. The dentine-enamel junction (DEJ) is accessible only directly adjacent to the cervix of the tooth. Therefore teeth have to be sectioned for studying marginal areas of the dental hard tissue. The potential of the technique for (pseudo) three-dimensional visualisation allows the study of an array of individual confocal images, the interpretation of which is similar to that of macroscopic tomographs (CT-scan, MRI). Additionally, the extended focus mode yields the overlay of individual confocal images in the form of a two-dimensional projection. This mode of operation proved to be particularly suited for the visualisation of odontoblast processes in their whole extension. The three-dimensional junction between enamel and dentine, the branches of the odontoblast processes and their interactions with the DEJ is demonstrable by CLSM without staining or other procedures of sample preparation. The direct microscopic comparison between samples, either fresh or kept in a humid chamber, and Technovit-embedded sample blocks gives evidence that the risk of artefacts by sample storage or by the embedding procedure is minimal. The tomographs limited to subsurface areas of the tissue also exclude mechanical surface artefacts due to grinding or cutting.

Dental Enamel↗
PubMed2006

Effects of hydrogen peroxide (H2O2) on alkaline phosphatase activity and matrix mineralization of odontoblast and osteoblast cell lines.

Hydrogen peroxide (H(2)O(2)), an oxidizing agent, has been widely used as a disinfectant. Recently, because of its reactive properties, H(2)O(2) has also been used as a tooth bleaching agent in dental care. This is a cause for concern because of adverse biological effects on the soft and hard tissues of the oral environment. To investigate the influence of H(2)O(2) on odontoblasts, the cells producing dentin in the pulp, we assessed cellular viability, generation of reactive oxygen species (ROS), alkaline phosphatase (ALP) activity, and nodule formation of an odontoblastic cell line (MDPC-23) after treatment with H(2)O(2), and compared those with the effects on preosteoblastic MC3T3-E1 cells. Cytotoxic effects of H(2)O(2) began to appear at 0.3 mmol/L in both MDPC-23 and MC3T3-E1 cells. At that concentration, the accumulation of intracellular ROS was confirmed by a fluorescent probe, DCFH-DA. Although more ROS were detected in MDPC-23, the increasing pattern and rate are similar between the two cells. When the cells were treated with H(2)O(2) at concentrations below 0.3 mmol/L, MDPC-23 displayed a significant increase in ALP activity and mineralized bone matrix, while MC3T3-E1 cells showed adverse effects of H(2)O(2). It is known that ROS are generally harmful by-products of aerobic life and represent the primary cause of aging and numerous diseases. These data, however, suggest that ROS can induce in vitro cell differentiation, and that they play a more complex role in cell physiology than simply causing oxidative damage.

Alkaline Phosphatase↗
PubMed1984

Improved preservation of intramitochondrial granules in rat-incisor odontoblasts by rapid-freezing and freeze-substitution fixation.

Odontoblasts fixed by rapid-freezing and freeze-substitution, compared to cells fixed with aldehyde, exhibited a larger number of microfilaments, a granular material inside the rough endoplasmic reticulum, many electron-dense aggregates in cytoplasmic vesicles and numerous intramitochondrial granules. Although these granules were located in odontoblasts facing a well-mineralized layer of dentine, this did not support the possible existence of a transfer pathway for intracellular calcium which plays some part in mineralization processes.

Animals↗
PubMed1984

The odontoblast process and its branches in human teeth observed by scanning electron microscopy.

Healthy teeth were fixed, resin-impregnated and freeze-fractured. Specimens were critical point-dried and examined by scanning electron microscopy. Odontoblast processes were observed in the inner-, middle- and peripheral dentine. The processes in the inner-third dentine closely approximated tubule wall and could be found in most of the tubules. Some tubules contained a thin fibre besides the odontoblast process. In the middle third of dentine, the processes became thinner, their appearance was cable-like with lateral branches and a wide periodontoblast space could be seen. Processes were seen only in a few tubules of outer-third dentine in both young and aged subjects. They divided into longitudinal and lateral branches and seemed to be connected with one another.

Adolescent↗