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At least 631 records · Page 35Linked to original sources
PubMed1998

Immune defense mechanisms of the dental pulp.

Defense reactions of the dentin/pulp complex involve a variety of biological systems, in which the immune system plays a pivotal role. The knowledge of the organization and function of pulpal immunocompetent cells has been sparse, but in recent years a significant body of information of immune mechanisms in general has provided a footing for substantial new knowledge of the immune mechanisms of the dental pulp. The identification of pulpal dendritic cells (DCs) has generated research activities which have led to a concept of how an antigenic challenge may evoke a pulpal inflammatory response. Although DCs are not able to identify foreign antigens specifically, they provide necessary signals to activate T-lymphocytes which in turn will orchestrate other immunocompetent cells to mount the local immune defense of the dental pulp. The purpose of this review is to accent the organization and function of pulpal DCs and other tissue and cellular components and to provide a basis for how they may interact to instigate pulpal defense mechanisms.

Antigen-Presenting Cells↗
PubMed1991

[Quantitative evaluation of the immunoglobulin G, A and M in the human dental pulp].

The presence of immunoglobulins G, A and M was studied in human dental pulps using a quantitative method of radial immunodiffusion. Valid data on the amounts of IgG, IgA and IgM were obtained on the basis of measured concentrations of immunoglobulins in each pulp sample and their correlation with total protein concentrations. The results indicated IgG to be present in 100%, IgA in 15% and IgM in 8% of 13 pulp samples affected by chronic inflammation. The mean values of IgG, IgA and IgM thus determined were 84.3, 4.4 and 1.4 mg/g protein, respectively. In intact pulp tissue, however, no presence of immunoglobulins G, A and M could be detected using the same method as above. The results obtained suggested the possibility of local synthesis of immunoglobulins in chronically inflamed pulp tissue, indicated that nonspecific inflammatory reaction may have occurred concurrently with some specific immunologic reactions. The predominance of IgG pointed to immunologic reactions of early types II and III hypersensitivity.

Dental Pulp↗
PubMed1977

Mapping of the trigeminal sensory complex of the cat. Characterization of its neurons by stimulations of peripheral field, dental pulp afferents and thalamic projections.

From a new systematic investigation of the 4 divisions of the trigeminal sensory complex, the following points are emphasized: 1. The subnucleus oralis receives a large representation from the oral cavity, a region also represented in the three other divisions of the trigeminal sensory complex. 2. Units responding to noxious mechanical stimulation have been found in two different loci: the subnucleus caudalis for the whole trigeminal area, and the subnucleus oralis for the oral cavity. 3. The dental pulp projects to the four divisions of the trigeminal sensory complex, but the heaviest projection is found in its rostral part (the main nucleus and subnucleus oralis). 4. Three distinct types of responses were found following dental pulp stimulation: primary, non primary and responses strongly enhanced by an increase in stimulus parameters.

Animals↗
PubMed1979

[The human dental pulp as viewed through a scanning electron microscope (author's transl)].

The human dental pulp was examined using a scanning electron microscope. The odontoblasts are pear-shaped and have a fine-grain surface structure. Tomes' process divides into fine branches before entering the predentin. Very few fibroblasts were found. These had stronger cell processes at the two terminal poles. Adhering to their surfaces were fine fibers. Collagenous and nerve fibers could not be accurately identified in the rich fibrillary network of the pulp. Stronger nerve fasciculi were readily observable through longitudinal sulci. Thinner fibers were seen to spread out in branches from some nerve bundles. The capillaries were observed to be surrounded by a sheath of fine fibrils.

Capillaries↗
PubMed1991

Human immunodeficiency virus infection of fibroblasts of dental pulp in seropositive patients.

Presence of human immunodeficiency virus (HIV) within noninflamed human dental pulps was documented by polymerase chain reaction assays in 11 of 12 pulps from HIV-seropositive patients. The purpose of the present study was to determine the cellular location of HIV in vivo within these tissues by means of in situ hybridization. Results of the in situ hybridization indicated HIV within fibroblasts of the pulp. These results are especially relevant because fibroblasts lack the CD4 receptor thought necessary for in vivo infection with HIV. These results suggest the fibroblast as a possible reservoir for HIV in the body.

CD4-Positive T-Lymphocytes↗
PubMed1999

Neurokinin-1 receptor expression in the mature dental pulp of rats.

Substance P induces inflammatory reactions in peripheral tissues including the dental pulp, but its regulatory effects in target tissues are dependent on receptor signalling. Here the expression of the substance-P receptor neurokinin-1 (NK1) in the mature molar pulp of the rat was examined in order to localize the main target areas for substance P. A polyclonal antibody directed against the C-terminal of the receptor was used, and immunohistochemistry was performed by the avidin-biotin peroxidase complex method. The results showed that the NK1 receptor was intensely expressed along vessel-like structures in the odontoblast and subodontoblast layer. A granulated and diffusely distributed NK1-receptor labelling was found along larger blood vessels in the root pulp and pulp proper. NK1 receptor-positive cells were frequently observed in the cell-rich zone beneath the odontoblast layer. The results indicate that, in the mature rat molar pulp, the main targets for substance P acting through the NK1 receptors are tissues related to blood vessels in the odontoblast and subodontoblast area. Furthermore, the expression of NK1 receptors on cells located in the subodontoblast area could indicate that substance P also affects cell functions in this area.

Animals↗
PubMed2001

Induction of dental pulp fibroblast matrix metalloproteinase-1 and tissue inhibitor of metalloproteinase-1 gene expression by interleukin-1alpha and tumor necrosis factor-alpha through a prostaglandin-dependent pathway.

Matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 (TIMP-1) are involved in the degradation of extracellular matrix in many inflammatory diseases. Little is known regarding the expression of these mediators in dental pulp fibroblasts. The effects of proinflammatory cytokines (interleukin (IL)-1alpha and tumor necrosis factor-alpha (TNF-alpha)) and prostaglandin E2 (PGE2) on pulp fibroblast MMP-1 and TIMP-1 gene expression were investigated. Northern hybridization showed that IL-1alpha and TNF-alpha induced significant MMP-1 gene expression, with only little effect on TIMP-1 gene. Exogenous PGE2, however, upregulated TIMP-1 mRNA synthesis but not MMP-1. Concomitant addition of IL-1alpha and PGE2 or TNF-alpha and PGE2 suppressed MMP-1 mRNA production, compared with the groups treated with IL-1alpha or TNF-alpha alone. In contrast, PGE2 enhanced the upregulatory effects of TIMP-1 mRNA by IL-1alpha or TNF-alpha. Furthermore, cytokine stimulation of MMP-1 and TIMP-1 gene expressions can be enhanced or blocked by indomethacin, respectively, and reversed by exogenous PGE2. These results suggested that cytokine-stimulated MMP-1 and TIMP-1 gene expression in dental pulp fibroblasts was mediated, at least in part, by a prostaglandin-dependent pathway. The differential regulation of IL-1alpha or TNF-alpha-induced MMP-1 and TIMP-1 mRNA synthesis, as well as the direct upregulation of TIMP-1 gene expression by PGE2, also implied that prostaglandin may serve as a protective mechanism from excessive tissue breakdown during pulpitis.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2005

Automatic stimulus breaker for electric dental pulp tester using pain response.

The pulp test provides a means of examining the vitality of dental pulp using physical or chemical stimulation. During electrical pulp testing, an electrical current stimulates the intradental nerve, which may be painful and stressful to patients. The study involved measurement of the electromyogram (EMG) from the anterior belly of the digastric muscle, finger movement and voice response during electrical pulp testing. The excessive stimulus time from the onset time of response (EMG, voice and finger movement) to the end of the stimulation was obtained. The results indicated that the responses occurred in the order: EMG, finger and voice. Based on these results, an automatic stimulus shut-off circuit was developed using the above-mentioned responses to stimulus during electric pulp testing. Excessive stimulus time was reduced by prompt switching-off of the pulp tester output, 64 ms on average after the first detected response (EMG). Consequently, excessive stimulus times were reduced by 284 and 152 ms on average for the subject and examiner disconnection, respectively, using the developed automatic shut-off circuit. Therefore it was possible to minimise pain and stress by reducing excessive pulp stimulation.

Adult↗
PubMed1985

Purification and kinetic properties of phosphofructokinase from dental pulps of rat incisors.

Phosphofructokinase (EC 2.7.1.11) was partially purified 19-fold from dental pulps of rat incisors, by ammonium-sulphate fractionation and phenyl-Sepharose chromatography with a recovery of about 95 per cent. With a 0.05 M tris-HCl buffer, the pH optimum of the enzyme was determined to be 8.4. At this pH, substrate inhibition of the enzyme by either fructose-6-phosphate (F6P) or ATP was not observed, and the relationship between reaction velocity and each substrate concentration was well explained by the Michaelis-Menten equation. The Km values were determined to be 5 X 10(-5) and 1.8 X 10(-4) M for ATP and F6P, respectively. The enzyme, however, showed different catalytic properties at pH 7.6, i.e. the kinetic behaviour was sigmoidal with respect to F6P and it was inhibited by high concentrations of ATP. The Hill coefficient for F6P was determined graphically to be 1.4. At pH 7.6, the enzyme activity was inhibited by citrate and phosphoenolpyruvate (PEP), neither of which showed any inhibitory effect on the enzyme at pH 8.4.

Adenosine Triphosphate↗
PubMed2006

Long-term cryopreservation of dental pulp stem cells (SBP-DPSCs) and their differentiated osteoblasts: a cell source for tissue repair.

It is not known whether cells derived from stem cells retain their differentiation and morpho-functional properties after long-term cryopreservation. This information is of importance to evaluate their potential for long-term storage with a view to subsequent use in therapy. Here, we describe the morpho-functional properties of dental pulp stem cells (SBP-DPSCs), and of their differentiated osteoblasts, recovered after long-term cryopreservation. After storage for 2 years, we found that stem cells are still capable of differentiation, and that their differentiated cytotypes proliferate and produce woven bone tissue. In addition, cells still express all their respective surface antigens, confirming cellular integrity. In particular, SBP-DPSCs differentiated into pre-osteoblasts, showing diffuse positivity for ALP, BAP, RUNX-2, and calcein. Recovered osteoblasts expressed bone-specific markers and were easily recognizable ultrastructurally, with no alterations observed at this level. In addition, after in vivo transplantation, woven bone converted into a 3D lamellar bone type. Therefore, dental pulp stem cells and their osteoblast-derived cells can be long-term cryopreserved and may prove to be attractive for clinical applications.

Adult↗
PubMed2006

Biodegradable porous calcium polyphosphate scaffolds for the three-dimensional culture of dental pulp cells.

AIM: To develop a three-dimensional culture model of human dental pulp cells (DPCs) with biodegradable porous calcium polyphosphate (CPP) scaffolds. METHODOLOGY: Human DPCs were isolated from three donors. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate the cytotoxicity of CPP compared with hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP). Values were analysed using unpaired t-tests. Cells were seeded onto porous CPP scaffolds with pore sizes in the range of 200-300 microm. The nature of cellular adaptation in the three-dimensional culture model was then evaluated visually by scanning electronic microscopy (SEM) and confocal laser scanning microscopy (CLSM). The apoptotic property of cells on the scaffolds was also assessed by DNA staining with CLSM. RESULTS: The cytotoxicity assay indicated that there was no significant difference between CPP and HA for each donor's original cells (P>0.05). Calcium polyphosphate had no cytotoxic effect on DPCs, whilst SEMs showed that cells successfully adhered to CPP scaffolds and spread amongst pores. On the cell surface, fine processes and matrix secretory granules were found. Confocal laser scanning microscopy showed that cells took on a three-dimensional structure with signs of vitality. CONCLUSION: Porous CPP scaffolds are promising for the establishment of a three-dimensional culture model of DPCs.

Apoptosis↗
PubMed2002

Effects of alginate hydrogels and TGF-beta 1 on human dental pulp repair in vitro.

The objective of this study was to investigate the use of alginate hydrogels to present either exogenous or endogenous transforming growth factor (TGF)-beta 1 to the dentin-pulp complex to signal reparative processes. Hydrogels were prepared, applied to cultured human tooth slices and the effects on tertiary dentinogenesis examined histologically. Both TGF-beta 1-containing and acid-treated alginate hydrogels, but not untreated hydrogels, upregulated dentin matrix secretion and induced odontoblast-like cell differentiation with subsequent secretion of regular tubular dentin matrix on cut pulpal surfaces. It is concluded that TGF-beta 1 can signal both induction of odontoblast-like cell differentiation and upregulation of their matrix secretion in the human dentin-pulp complex. Alginate hydrogels provide an appropriate matrix in which dental regeneration can take place and may also be useful for delivery of growth factors, including TGF-beta s, to enhance the natural regenerative capacity of the dental pulp.

Acids↗
PubMed1999

Long-term histologic changes in the dental pulp after posterior segmental osteotomies.

OBJECTIVE: The purpose of this study was to examine pulp tissue for 18 months after segmental osteotomy in nonhuman primates. STUDY DESIGN: In this long-term experimental study, subapical, posterior, maxillary, and mandibular osteotomies were done in 26 baboons (Papio ursinus). Baboons were killed humanely immediately after operation and at 3, 6, 12, and 18 months, when tissues were perfusion-fixed. Longitudinal step-serial sections of dental pulps were examined. RESULTS: There was a loss of the odontoblast layer as early as 3 months after surgery. Inflammatory cell infiltrate was most marked in the early postoperative stages, and the formation of osteodentin and secondary dentin was evident after 6 months. Foci of necrosis were present in the 3-month and 6-month groups but were replaced by pulp fibrosis in the 12-month and 18-month groups. All these changes were more frequent in experimental than control teeth. CONCLUSIONS: The histologic changes seen should not affect the prognosis of teeth in subapical osteotomy segments if clinicians are careful not to damage root apices and do regular, careful, clinical, and radiographic follow-up examinations. Because many pulps healed spontaneously in the study teeth, endodontic treatment should be delayed until it is clearly needed.

Animals↗