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PubMed1994

Ultrastructure of the neuromuscular junction of vasomotor nerves in the microvasculature of human dental pulp.

Vasomotor nerves in human dental pulp were more closely related to arterioles than to venules. Most were composed of unmyelinated fibres, which were mainly adrenergic. They appeared close to arterioles that were surrounded by a few layers of contractile smooth-muscle cells. The smaller arterioles with a diameter of 10-15 microns received a more intimate innervation by vasomotor nerves than did the larger. These vessels occasionally showed much narrower neuromuscular junctions than previously reported. Most of these nerve fibres were identified as adrenergic by the presence of chromaffin-positive synaptic vesicles detected by ultrastructural enzyme histochemistry. Their function appeared to be to regulate the blood flow and/or the blood pressure by stimulating smooth-muscle cells, resulting in contraction and a change in the calibre of the vessels. Capillaries and venules, which have a higher permeability, received weaker innervation by the vasomotor nerves than did arterioles. The intimate relation between vasomotor nerves and arterioles is related to the function of dental pulp in normal and pathological conditions.

Adrenergic Fibers↗

PubMed1988

Optical assessment of dental pulp vitality.

The assessment of dental pulp vitality is an important part of oral diagnosis. Conventional tests stimulate the nerves in the pulp and rely on a subjective response from the patient. The use of an optical method for assessment of pulp vitality has been investigated. Fibre optic light guides were used to transmit light to and from the tooth and signal processing was employed to enhance the resulting signal. Valid pulse signals were differentiated from artefactual signals by analysis of signal parameters. Artefactual signals were found to have coefficients of variability that are greater than 40% for amplitude and greater than 25% for phase. With this technique it has been possible to recognize a pulse signal from over 70% of healthy teeth. Further work is in progress to develop the technique to a state where it can be used as a routine clinical tool.

Algorithms↗

PubMed2005

[Isolation and identification of huamn dental pulp stem cells].

OBJECTIVE: To isolate and identify human dental pulp stem cells from third molars. METHODS: Dental pulps were dissected and digested by collagenase type I and dispase. The obtained single cell supernatant were harvested and cultured. Characterization of the phenotype of DPSCs was detected by immunohistochemical method and RT-PCR assay. Cell cycle was analyzed by FCM. Differentiation potential of DPSCs was evaluated. RESULTS: Colony-forming efficiency of cells derived from dental pulp tissue was 2 - 15 clones/10(3) cells plated. DPSCs were found to express many different markers, including vimentin, collagen type I, GFAP, nestin and osteocalcin, while they failed to react with MyoD and DSPP. About 64.1% of the cells were in G0/G1 phases, while only 35.8% in proliferation (S + G2 + M). Grown in an adipogenic cocktail medium for three weeks, some DPSCs expressed fat cell markers of PPARgamma and LPL, and formed oil red O-positive lipid clusters in five weeks. After culture with a myogenic-inductive medium, DPSCs were found to express MyoD, desmin and myosin, markers of myocyte. Long-term cultures of DPSCs grown in differentiation inductive medium demonstrated the capacity to form Von Kossa-positive condensed nodules with high levels of calcium. CONCLUSION: Cells isolated from adult human dental pulp are clonogenic, and have multipotent differentiation potential, satisfying the criteria of postnatal somatic stem cell.

Adult↗

PubMed2005

Reduction of osteocalcin expression in aged human dental pulp.

AIM: To investigate the expression of osteocalcin mRNA in young and in aged human dental pulp tissue to determine the characteristics of osteocalcin expression. METHODOLOGY: Human dental pulp tissues of the third molars were obtained from healthy young (17-23 years) and aged (>50 years) subjects, and total RNA was extracted. Osteocalcin mRNA expression was determined by RT-PCR and by quantitative real-time RT-PCR (QRT-PCR). The threshold cycle (Ct) value, which reflects the amount of PCR, was calculated and the difference between the value in young and aged pulp was statistically analysed. RESULTS: Osteocalcin mRNA was detected in all samples of human dental pulp tissue homogenates by RT-PCR analysis. Osteocalcin mRNA was expressed in young adult dental pulp but was decreased in aged human dental pulp. QRT-PCR analysis also showed a reduced expression of osteocalcin mRNA in aged human pulp. Expression of osteocalcin in young human pulp was significantly higher (about sixfold) than in aged pulp (P<0.01, Mann-Whitney U-test). CONCLUSION: Reduction of osteocalcin expression may be associated with the loss of viability in human dental pulp tissue, and may be a characteristic of aged human dental pulps.

Adolescent↗

PubMed2003

Lymphangiogenesis in human dental pulp.

AIM: To investigate the impact of inflammation on lymphangiogenesis in human dental pulp. METHODOLOGY: Eleven samples of dental pulp without inflammation and 11 dental pulps with moderate to intense mononuclear cell inflammatory infiltrate associated with dentine caries were selected. The streptavidin-biotin complex stain was used to detect CD31, vascular endothelial growth factor receptor-3 (VEGFR-3) and alpha-smooth muscle actin. The number of lymphatic vessels was obtained by counting the number of vessels positive for CD31 and VEGFR-3 and negative for alpha-smooth muscle actin. RESULTS: The results demonstrated that the mean number (+/-SD) of vessels positive for CD31 and VEGFR-3 (lymphatic vessels) in the group with inflammation (6.09 +/- 1.81) was statistically higher (P = 0.0123) than the mean number in the group without inflammation (3.73 +/- 2.20). CONCLUSION: Increased co-immunostaining of CD31 and VEGF-3 in vessels associated with human dental pulp inflammation occurred, which suggests lymphangiogenesis.

Actins↗

PubMed2001

[Evaluation of the process of recovery of dental pulp after Le Fort I osteotomy].

Le Fort I osteotomy has been established by many studies and is generally used, but hypoesthesia of the dental pulp, the most common complication, occurs in almost all patients. As such, we examined dental pulp sensibility, pulpal blood flow, and histological changes, to elucidate the process of functional recovery of dental pulp after Le Fort I osteotomy. Monkeys (Macaca fusucata) were used in this study. The animals underwent Le Fort I osteotomy in their unilateral maxillae. Histological and angiographic examinations were performed to observe the postoperative changes in the maxillae and dental pulp. Postoperative pulpal blood flow was examined using a laser Doppler flowmetry. Postoperative pulpal blood flow, by a laser Doppler flowmetry, and dental pulp sensibility, by electrodiagnostics, in patients who underwent Le Fort I osteotomy, were also examined. Although nerve fibers observed in the dental pulp of the maxilla degenerated and disappeared by one week postoperatively, they reappeared sparsely from two to three months after osteotomy, and there were abundant nerve fibers by one year postoperatively. In the angiographic examination, blood supply to the maxillary dental pulp was maintained throughout the postoperative period. In the examinations of laser Doppler flowmetry and dental pulp electrodiagnostics, ischemia in the dental pulp for three or four days after osteotomy might delay the recovery of dental pulp sensibility. These results suggested that blood flow in dental pulp at three or four days after surgery may affect the recovery of dental pulp sensibility.

Animals↗

PubMed2003

Production of colony-stimulating factor in human dental pulp fibroblasts.

Class II major histocompatilibity complex (MHC)-expressing cells are usually distributed in dental pulp, and it was postulated that the colony-stimulating factor (CSF) derived from dental pulp fibroblasts contributes to the migration of class II MHC-expressing cells into pulp tissue. This study aimed to investigate the CSF production of human dental pulp fibroblasts. In pulp tissue sections, granulocyte (G)-CSF was detected from normal teeth, while G-CSF, macrophage (M)-CSF, and granulocyte-macrophage (GM)-CSF were detected from teeth with dentinal caries. In cultured dental pulp fibroblasts, G-CSF was detected by immunostaining, immunoprecipitation, and ELISA, and mRNAs of G-CSF, M-CSF, and GM-CSF were detected by RT-PCR. The dental pulp fibroblasts cultured with TNF-alpha were found to increase the G-CSF expression and to produce M-CSF and GM-CSF. These findings suggest that dental pulp fibroblasts usually produce G-CSF. In the presence of TNF-alpha, dental pulp fibroblast express M-CSF and GM-CSF.

Adolescent↗

PubMed1987

[Proposal of a new analgesia test based on the observation of nociceptive behavior induced by electric stimulation of dental pulp in the rat].

Dental pulp was electrically stimulated in the awake rat. When the stimulus intensity was progressively increased the following four nociceptive reactions successively appeared: jaw opening reflex, scratching, head rotation, vocalization. The threshold of these four reactions was observed before and after administration of three antalgic drugs. No action of the three drugs was observed for the jaw opening reflex. However each drug showed different actions on the other three reactions.

Analgesia↗

PubMed1996

Stimulation of interleukin-1beta-independent interleukin-6 production in human dental pulp cells by lipopolysaccharide.

Dental pulpal infection is most commonly caused by extensive dental caries. A principal driving force behind pulpal disease response appears to lie in the immune system's response to bacteria. However, the production of interleukin (IL)-1beta and IL-6 in human dental pulp (HDP) cells in response to lipopolysaccharide (LPS) has not been well characterized. We examined IL-1beta and IL-6 production in HDP cells by challenging with LPS from Porphyromonas endodontalis, which is a Gram-negative bacteria found in root canals. Our results presented here showed that when HDP cells were stimulated by LPS, the production of IL-6 always preceded that of IL-1beta. Since the IL-6 production was observed even in the presence of the IL-1beta receptor antagonist, we concluded IL-6 production was independent of the IL-1beta molecule in LPS-stimulated HDP cells. This idea was further supported by the results obtained from RT-PCR experiments, in which IL-6 mRNA, but not IL-1beta mRNA, was present in the RNA preparation isolated from the early stage of cells.

Cells, Cultured↗

PubMed2003

Immunolocalization of bone extracellular matrix proteins (type I collagen, osteonectin and bone sialoprotein) in human dental pulp and cultured pulp cells.

AIM: To simultaneously analyse the expression of type I collagen, osteonectin and bone sialoprotein (BSP) in human dental pulp of different ages. METHODOLOGY: Cultured dental pulp fibroblasts (FP1 cell line), pulps from dental germs with incomplete root formation (n = 4) and pulps of erupted teeth with total root formation (n = 4) were used. Bone proteins were searched by immunohistochemistry and immunofluorescence using polyclonal antibodies and compared among the three groups assessed. RESULTS: Immunohistochemistry detected the three proteins in dental pulp tissue, as it labelled extracellular matrix, predentine and odontoblasts. The BSP label was weaker, when compared to both type I collagen and osteonectin. The presence of type I collagen was more evident in pulps from erupted teeth, when compared to germ dental pulps. On the other hand, a strong expression of osteonectin in germ dental pulps was observed. CONCLUSIONS: Regardless of the degree of maturation, dental pulps present type I collagen, osteonectin and BSP in the extracellular matrix (ECM) and in the odontoblastic layer. Thus, the results suggest that these proteins are related to the production and mineralization of dentine.

Cell Line↗

PubMed1978

[Influence of hydrone on the dental pulp as compared to other drugs].

The possibility of application of gel-collagen-hydronic sponge was examined on calf teeth. The action was observed after the 4, 7 , 14, 21 and 28 days. The biological properties of the sponge alone were examined in the close contact to dental pulp. The reaction of dental pulp to this contact was settled. Simultaneously the application of this plastic was examined as a ground of different materials usually applied in the treatment of dental pulp diseases. The reaction of dental pulp to the close contact of gel-collagen-hydronic sponge was compared to the action of the sponge additionally suturated with a 0.5% solution of Cortisone, the sponge mixed with Framycoin powder, or saturated with a mixture of 0.5% solution of Cortisone and Framycoin the collagenic sponge, Caryosan, Calxyd, and to the reaction of uncovered and untreated dental pulp. It was ascertained that gel-collagen-hydronic sponge contacted with calf's dental pulp doesn't impede the composing of osseous-dentinal barrier and its porosity is gradually filled up with a numerous cell elements, later also with strands of tissue. The sponge may be applicated as a ground of examined materials. Within these materials the best composing of osseous-dental barrier was found after the application of Calxyd and then successively after the application of Caryosan, hydronic sponge alone, sponge with Framycoin, sponge saturated with dilution of Cortisone and Framycoin, and collagenic sponge, which gave the worst reaction of calf's dental pulp, similar to the reaction of uncovered and untreated dental pulp.

Animals↗

PubMed1999

Influences of 4-meta/MMA-TBB adhesive resin on osteodentinogenesis of transplanted rabbit dental pulp in vivo: immunohistochemical and electronmicroscopic studies.

The purpose of this study was to investigate the influence of 4-META/MMA-TBB adhesive resin (4-META resin) on osteodentinogenesis of transplanted pulp in vivo. Dental pulp was obtained from the incisors of adult rabbits. 4-META resin was applied to the pulp tissue, and the pulp tissue with 4-META resin was autotransplanted beneath the renal capsule with the pulp side touching the kidney. Pulp tissue alone was also transplanted as a control. The animals were sacrificed at 3, 7, and 14 days after the experiment, and the specimens were examined morphologically. At 3 days, proliferation of mesenchymal cells was observed, and alkaline phosphatase activity (ALP) and osteocalcin were detected throughout the entire transplanted pulp area. In the experimental case, a thin, highly electron dense zone and a granular layer were observed. Under this layer, only a cell-membrane-like structure, a cell with an unclear nucleus, a nucleus alone, and an organelle-like structure could be seen. Furthermore, an exudative layer with many neutrophils was observed, and apoptotic-body-like structures were also found in some areas. On days 7 and 14 in the control group, osteoblast-like cells had proliferated, and osteodentin formation was initiated throughout the entire transplanted pulp area. In the experimental cases at 7 and 14 days, the entire transplanted area had become osteodentin except for a thin fibrous layer under the 4-META resin. These results suggested that the components of 4-META resin such as MMA and 4-MET (A), which guide the polymerization, might cause degeneration of, but not disturb, the wound healing of the pulp tissue.

Acrylic Resins↗

PubMed1999

Effect of dental material HEMA monomer on human dental pulp cells.

The purpose of this study was the cytotoxicity assay of dental material HEMA monomer to human dental pulp cell by MTT method and application of the flow cytometry to analyze effect of dental material on the cell cycle progression. The result of MTT method showed the inhibition of cell growth and 50% inhibitory concentration (IC50) of HEMA monomer in human dental pulp cell was 815.19 micrograms/ml. The result of the flow cytometry showed that there was a perturbation on human dental pulp cell cycle progression at the phases of Sand G2M with a dose-dependent manner. Biomaterials including dental materials should be safety to human bodies. Presently, many methods for testing the cytotoxicity of biomaterials were suggested. [1-2] MTT method is one of the cytotoxicity assay. It was provided by Monsmnn. [3] MTT is a kind of tetrazolium salt [3-(4,5-dimethylthiazol-2yi)-2,5-diphenyl tetrazolium bromide]. MTT method is the rapid, precision and quantitative colorimetric assay for cytotoxicity. It can be used to measure the proliferation, cytotoxicity or activation of living cells and is capable of handling large number of samples. Many investigators have used this advanced method.[4] Flow cytometry (FCM) analyzes the quantity of DNA bonded with dyes in each cell. It can provided the information of the cell cycle progression in detail. Currently, flow cytometry has been widely and successfully used in various fields of basic science research and clinical medicine. This FCM technology also can be used to study the cytotoxicity of dental materials and evaluate the biocompatibility of dental materials.[5-6] The contents of the study were (1) cytotoxicity assay on dental material HEMA monomer in human dental pulp cells by MTT method. (2) application flow cytometry to analyze the effect of dental material HEMA monomer on the cell cycle progression of the human dental pulp cells.

Cell Cycle↗

PubMed2005

[Effect of hepatocyte growth factor on the proliferation of dental pulp cell].

OBJECTIVE: To study the effect of hepatocyte growth factor on the proliferation of dental pulp cell. METHODS: The 4th generation dental pulp cell cultured in vitro was used as target cell. 1- 200 microg/L hepatocyte growth factor was added in the test group while the pure cell culture DMEM as control. The MTT method and flowcytometry were applied to assay the proliferation and cell cycle of dental pulp cell of different groups. RESULTS: 1-200 microg/L hepatocyte growth factor showed promoting effect to the proliferation of pulp cell since the 5th day (P < 0.05). 100 microg/L was found to be the optimal concentration. Also on the 5th day, 100 microg/L hepatocyte growth factor decreased the G1 subcycle and increased the S subcycle of dental pulp cell ( P < 0.05). While on the 3rd day, it had no effect on the cell cycle. CONCLUSION: Hepatocyte growth factor had positive effect on the proliferation of dental pulp cell, with 100 microg/L as the optimal concentration.

Cell Culture Techniques↗

PubMed2004

Reduction of connexin 43 expression in aged human dental pulp.

AIM: To investigate the expression of connexin 43 (CX43) mRNA in young and old human dental pulp tissues to determine the characteristics of CX43 expression. METHODOLOGY: Samples were obtained from human dental pulp of healthy young (17-23 years) and aged (>50 years) subjects. CX43 expression was determined by RT-PCR and by quantitative real-time RT-PCR (QRT-PCR). The threshold cycle (Ct) value, which reflects the amount of PCR, was calculated and the difference between value in the young pulp and that in the aged pulp was statistically analysed. RESULTS: RT-PCR analysis of human dental pulp tissue detected CX43 mRNA in all the samples. CX43 was abundantly expressed in young adult dental pulp, but expression of CX43 mRNA was dramatically decreased in aged human dental pulp. QRT-PCR analysis also showed the reduced expression of CX43 in aged pulp, and expression of CX43 in young pulp was significantly higher (about 10-fold, P < 0.01, Mann-Whitney U-test). CONCLUSION: Reduction of CX43 expression may be associated with the loss of viability in human dental pulp, and is considered as one characteristic of aged pulp.

Adolescent↗

PubMed2000

The role of vascular endothelial growth factor in human dental pulp cells: induction of chemotaxis, proliferation, and differentiation and activation of the AP-1-dependent signaling pathway.

Vascular endothelial growth factor (VEGF) is a potent mitogen in endothelial cells, but little is known about its activity in other cell types. To clarify the role of VEGF in human dental pulp cells and pulp tissue, we investigated the effects of VEGF on the chemotaxis, proliferation, and differentiation of human dental pulp cells. VEGF induced a strong chemotactic response in human dental pulp cells in a dose-dependent manner. VEGF also marginally enhanced the proliferation of human dental pulp cells and induced an increase in alkaline phosphatase in human dental pulp cells. However, these effects of VEGF were not observed in reference to human skin fibroblasts. Analyses by the reverse-transcription/polymerase-chain-reaction method and flow cytometry showed that the mRNAs of two VEGF receptors, fins-like tyrosine kinase and kinase insert domain-containing receptor, were expressed in human dental pulp cells, whereas only fms-like tyrosine kinase mRNA was expressed in human skin fibroblasts. VEGF induced the activation of activator protein 1 (AP-1) and c-fos mRNA expression in human dental pulp cells. The AP-1 inhibitor curcumin strongly inhibited VEGF-induced alkaline phosphatase production in human dental pulp cells. In addition, VEGF antisense oligonucleotide suppressed the production of VEGF and alkaline phosphatase in human dental pulp cells. These results suggest that VEGF produced by human dental pulp cells acts directly upon human dental pulp cells in an autocrine manner, and may promote the chemotaxis, proliferation, and/or differentiation of human dental pulp cells via the utilization of kinase insert domain-containing receptor and in part through AP-1 by increasing c-fos.

Alkaline Phosphatase↗

PubMed2006

Effects of growth factors on dental pulp cell sensitivity to amalgam toxicity.

OBJECTIVES: The objective was to determine the effects of growth factor treatment on dental pulp cell sensitivity to toxicity. METHODS: The toxicity of zinc-containing and zinc-free dental amalgam was tested on four types of cells; glia, neurons, embryonic stem cells, and dental pulp cells. The effects of six different growth factors were tested on dental pulp cell sensitivity to amalgam toxicity. RESULTS: Zinc-containing amalgam was highly toxic to all cell types tested. Zinc-free amalgam was less toxic, but it was most toxic to dental pulp cells. Exposure of dental pulp cells to the growth factors IGF-I or BMP-7 had no effect on their morphology or rate of cell division, and did not alter their sensitivity to zinc-free amalgam toxicity. Exposure to EGF, bFGF, or TGF-beta altered the morphology and decreased the rate of cell division, and the cells were no longer sensitive to zinc-free amalgam toxicity. Exposure to BMP-2 also altered the morphology and decreased the rate of cell division, but the cells remained sensitive to zinc-free amalgam toxicity. SIGNIFICANCE: The results indicate that untreated dental pulp cells are highly sensitive to amalgam toxicity, but that sensitivity can be decreased by exposure to certain growth factors. Therefore, for treatment of conditions in which pulp cells may come in contact with substances released from dental materials, such as pulp capping, the use of amalgam should be avoided unless the pulp cells are first treated with the proper growth factors.

Analysis of Variance↗

PubMed1999

In vitro study of the effects of endothelin-1 on human dental pulp cells.

OBJECTIVE: To study the effect of Endothelin-1 (ET-1) on cell proliferation in primary cultures of human dental pulp cells; the cell mechanism of mitogen; and collagen synthesis. METHODS: Primary cultures of human dental pulp cells; Thiazolyl Blue Tetrazolium Bromide (MTT) test to investigate cell proliferation; measurement of calcium ions in human dental pulp cells with the calcium-sensitive dye fluo-3; enzyme-linked immunosorbent assay and avidin-biotin complex immunocytochemical assay for collagen synthesis in human dental pulp cells. RESULTS: Incubation of cultures with ET-1 resulted in a dose-dependent increase in cell proliferation over control (unstimulated) cultures. In addition ET-1 increased the Ca2+ concentration in human dental pulp cells, which cannot be inhabited by Verapamil. The finding demonstrated that collagen type I synthesis of human dental pulp cells was increased by ET-1. CONCLUSIONS: ET-1 played a crucial role in pulp restoration of lesions and had an effect on mitogen and differentiation of human dental pulp cells.

Cell Division↗