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Results for “DENTAL PULP”

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PubMed1980

Altered vascular permeability in the dental pulp of traumatised rat teeth.

A study was made of the vascular permeability changes occurring in the dental pulp of rat teeth subjected to trauma of the occlusal surface with a special steel burr. The vascular response was measured by leakage of 131I-labelled human serum albumin and of colloidal carbon. The effect of a variety of inhibitors of increased vascular permeability was observed. The results obtained support the hypothesis that in the model studied the vascular response of the dental pulp is mediated by the sequential release of histamine and 5-HT, kinins and prostaglandins.

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↗
PubMed2005

Expression and characterization of vanilloid receptor subtype 1 in human dental pulp cell cultures.

The expression of the vanilloid receptor subtype 1 (VR1, TRPV1) was detected in human dental pulp fibroblasts (PF-10) using RT-PCR, Western blotting, and immunocytochemical analysis. As revealed by ELISA, capsaicin induced IL-6 expression in PF-10 cells, and the VR1 antagonist capsazepine dose-dependently inhibited capsaicin-induced IL-6 production, indicating that capsaicin-induced IL-6 expression is related to VR1 activation. The interaction between capsaicin and mitogen-activated protein kinases (MAPKs) was investigated. The phosphorylation of p38 MAPK and c-Jun NH2-terminal kinase (JNK) were detected after capsaicin stimulation. p38 MAPK is involved in capsaicin-induced IL-6 production, as shown by the use of specific inhibitors of this kinase. The result of EMSA showed that capsaicin inhibited tumor necrosis factor-alpha (TNF-alpha)-induced nuclear factor-kappa B (NF-kappaB) activation in PF-10 cell cultures. These results suggest that the activation of VR1 plays an important role in dental pulp inflammation.

Adult↗
PubMed1996

Interleukin-1 alpha stimulates interstitial collagenase gene expression in human dental pulp fibroblast.

Interstitial collagenase (matrix metalloprotease-1) is a member of a family of matrix metalloproteases and is thought to play a role in degradation of the extracellular components, such as collagens in normal extracellular matrix remodeling and in many disease processes. We examined interstitial collagenase mRNA expression in human dental pulp fibroblast cultures by Northern blot analysis. These cells did not express interstitial collagenase mRNA in an unstimulated condition. Inflammatory cytokines, such as interleukin-1 alpha, induced interstitial collagenase mRNA expression in these cells. The interstitial collagenase mRNA levels began to increase after 2-h exposure, reaching a maximum after 8 h, then dropping to the unstimulated level at 48 h. These effects were observed in a dose-dependent manner in a dose range of 0.1 to 10 ng/ml. Transforming growth factor-beta reduced the levels of interstitial collagenase mRNA expression that were induced by interleukin-1 alpha. These observations suggest that interstitial collagenase mRNA expression in human dental pulp fibroblasts is regulated by the inflammatory cytokines and that interstitial collagenase may play a role in tissue degradation in inflamed dental pulp.

Adolescent↗
PubMed1992

Osteogenic activity of cells from dental pulp, periodontal ligament, bone marrow and muscle in vitro: an ultrastructural study and alkaline-phosphatase activity.

Dental pulp, periodontal ligament, bone marrow and muscle tissue from the same rat were cultured in vitro in order to investigate their osteogenic activity by transmission electron microscope. Immunohistochemical methods with various antibodies were utilized and alkaline-phosphatase (ALPase) activities of these cells were also measured biochemically. Dental pulp cells were stellate in shape, showed an intense ALPase reaction, and had lipid-like droplets. Periodontal ligament cells were composed of spindle fibroblasts and epithelial cells. The former revealed a positive reaction for ALPase and possessed microfilaments. Bone marrow cells were spindle shaped, resembling fibroblasts, but some of them were similar to osteoblasts. Muscle cells were long, slender in shape, and showed no positive reaction for ALPase. The cells from pulp tissue showed the highest activity of ALPase, followed by periodontal ligament and bone marrow; there was no activity in muscle tissue. All the cells except the epithelial-like cells of the periodontal ligament and muscle cells were positive in reaction with ALPase which is a marker for osteogenic cells, and vimentin which is a marker of fibroblastic characteristics. Osteogenic activity and cellular differentiation of these cells were discussed.

Alkaline Phosphatase↗
PubMed1981

Polyacrylamide gel electrophoresis of the alkaline phosphatase of rat dental pulp.

Judging from the mobility after the sodium dodecyl sulphate-gel electrophoresis, the mol. wt of the dental pulp enzyme was estimated to be 125,000-130,000. The electrophoretic behaviour of this enzyme was identical with that of calvarial phosphatase but not with those of kidney and intestinal enzymes. These results suggest that the dental pulp enzyme has a similar molecular structure to bone alkaline phosphatase.

Alkaline Phosphatase↗
PubMed1993

Patterns of nerve regeneration in dental pulps of monkeys following surgical transection at 1 year.

Previous studies have reported revascularization and reorganization of dental pulp chambers with periodontal tissues of monkeys following complete surgical transection through a portion of the apical roots. This study observed 128 teeth in four adult monkeys. Following surgical transection, the tissues were acquired by perfusion fixation, serially sectioned, and stained for cellular detail with hematoxylin and eosin. Collagen tissues were stained with Preece's trichrome and neural tissues with Rowles' silver cyanate for controlled impregnation. At 1 and 2 weeks the coronal tissues showed tissue disruption, necrosis, and degenerating nerves. The 3- and 4-week tissues that had been completely transected showed replacement healing of the pulp tissue with periodontal ligament connective tissue, but no nerves were present. At 6 weeks, no nerves were present in the coronal chambers of those teeth with complete vital transection. The 24-, 36-, and 52-week pulp chambers with complete transection failed to show nerve fibers in their reorganized connective tissues.

Animals↗
PubMed1999

The distribution and ultrastructure of class II MHC-positive cells in human dental pulp.

The distribution and ultrastructure of class II major histocompatibility complex (MHC)-positive cells were investigated in human dental pulp, employing immunohistochemistry using an anti-human leukocyte antigen (HLA)-DR-monoclonal antibody. HLA-DR-immunopositive cells, appearing spindle-like or dendritic in profile, were densely distributed throughout the dental pulp. Under the electron microscope, these cells exhibited various sizes of vesicles containing clear or opaque contents, multivesicular bodies and characteristic fine tubulovesicular structures in their cytoplasm. Some reactive cells possessed coated pits and vesicles including electron-dense materials, indicating an active endocytosis. At the periphery of the pulp tissue, the HLA-DR-immunopositive cells were predominantly situated in the subodontoblastic layer, with some located in the odontoblast layer and/or predentin and extending their cytoplasmic processes into the dentinal tubules. Cell processes of these cells occasionally made contact with several odontoblast processes in the same way as the nerve fibers in the predentin. These cells never contained the typical phagosomes frequently observed in the HLA-DR-immunoreactive macrophages in the subodontoblastic layer and the pulp core. The results suggest that the HLA-DR-immunopositive cells in the odontoblast layer and/or predentin have some regulatory function on the odontoblasts under physiological conditions, in addition to their involvement in the initial defense reaction after tooth injury.

Cytoplasmic Granules↗
PubMed1999

Activation of excitatory amino acid receptors in bovine dental pulp evokes the release of iCGRP.

The activation of excitatory amino acid (EAA) receptors within the central nervous system is associated with numerous centrally mediated phenomena, including hyperalgesia. However, relatively little is known about the peripheral mechanisms which these receptors may regulate when activated. This research evaluated the hypothesis that EAA receptors in bovine dental pulp activate a population of peptidergic sensory neurons as measured by the release of immunoreactive calcitonin gene-related peptide (iCGRP), a neuropeptide associated with neurogenic inflammation. In vitro superfusion of bovine dental pulp was used to evaluate the regulation of iCGRP secretion by the EAA receptor agonists AMPA, kainate, NMDA, and L-glutamate. Both AMPA and kainate stimulated the release of iCGRP in a concentration-dependent manner (AMPA EC50 = 0.27 +/- 3.3 nM; kainate EC50 = 3.2 +/- 1.1 microM). Pre-treatment and co-administration of the AMPA/kainate receptor antagonist CNQX significantly reduced the iCGRP release evoked by either of these agonists. In contrast, neither NMDA nor L-glutamate induced any consistent changes in iCGRP release. These results suggest that the activation of AMPA and kainate receptors in dental pulp may contribute to peripheral release of vasoactive neuropeptides which mediate a neurogenic component of inflammation.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed2006

Substance P stimulates release of RANKL via COX-2 expression in human dental pulp cells.

OBJECTIVE: Our previous study found that substance P (SP), a sensory neuropeptide, was expressed in the dental pulp of rats during experimental tooth movement. We examined the effects of SP on the production of prostaglandin (PG) E2 and the receptor activator of nuclear factor- B ligand (RANKL) by human dental pulp fi broblast-like (HDPF) cells. MATERIALS AND METHODS: SP was added to cultured HDPF cells at concentrations ranging from of 10(-4) to 10(-12) mol/L. PGE2 and soluble RANKL (sRANKL) levels were determined using enzyme-linked immunosorbent assay kits. Gene expression was confi rmed by RT-PCR analysis. Pit formation assays using dentin slices were carried out to examine the effect of SP on osteoclastogenesis. RESULTS: The levels of PGE2 and sRANKL increased in the presence of SP, though the increases were greater in the experimental groups in both a time- and concentration-dependent manner, and the increase of RANKL was partially mediated by PGE2. The gene expression of cyclooxygenase (COX)-2 and RANKL was up-regulated, and conditioned medium samples obtained from HDPF cells treated with SP induced bone resorption. CONCLUSIONS: SP stimulated the production of PGE2 and RANKL, and promoted bone resorption. Therefore, SP may be involved in pulpal inflammation and root resorption during orthodontic tooth movement.

Adolescent↗
PubMed1987

5-Hydroxytryptamine stimulates the release of prostacyclin but not thromboxane A2 from isolated rat dental pulp.

The effect of 5-hydroxytryptamine (5-HT) on the release of prostacyclin and thromboxane (TX) A2 from isolated rat dental pulp was evaluated. 5-HT (1-1,000 microM) caused a dose-dependent and marked stimulation of the release of prostacyclin but not TXA2. Of the 5-HT-related indolealkylamines tested, only tryptamine had a similar stimulatory effect while tryptophan and 5-hydroxytryptophan had no effect. Neither histamine (100 microM) nor bradykinin (100 microM) had such an effect. Our results suggest the possible involvement of 5-HT receptors in 5-HT-induced stimulation of prostacyclin production in rat dental pulp.

Animals↗