[IN VITRO STUDIES ON THE PERMEABILITY OF THE DENTAL HARD SUBSTANCE FOR THE DETERMINATION OF PROTEIN CATABOLISM OCCURRING IN POSTMORTAL DENTAL PULP DISINTEGRATION].
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Dental Pulp↗
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Elephant dental pulp tissue: where are the nerves?
Dental pulp tissue from three elephants was examined histologically with hematoxylin and eosin and s-100 protein stains. In all specimens, normal pulp was found with the exception that no nerve fibers (myelinated or non-myelinated) were demonstrable in any of the numerous sections prepared.
Animals↗
Neuropeptide Y-immunoreactive primary afferents in the dental pulp and periodontal ligament following nerve injury to the inferior alveolar nerve in the rat.
The distribution of neuropeptide Y (NPY)-immunoreactive (IR) primary afferents in the dental pulp and periodontal ligament of the rat mandible were examined following combined chronic constriction injury (CCI) of the inferior alveolar nerve (IAN) and sympathectomy of the superior cervical ganglion (SCG). NPY-IR nerve fibers were observed around the blood vessels in the trigeminal ganglion, dental pulp and periodontal ligament in normal animals. Following combined CCI of the IAN and sympathectomy of SCG (SCGx), perivascular NPY-IR nerve fibers originating from SCG disappeared completely, but many NPY-IR nerve fibers coming from the trigeminal ganglion appeared in the dental pulp and periodontal ligament. In the molar dental pulp, thick NPY-IR nerve fibers were observed within the nerve bundle, and some thin NPY-IR nerve fibers ran towards the odontoblast layer; very few NPY-IR nerve fibers were observed in the incisor pulp. In the periodontal ligament of molar, thick NPY-IR nerve fibers appeared at the alveolar part following combined CCI of IAN and SCGx. In the lingual portion of the periodontal ligament of the incisor, many thick NPY-IR nerve fibers were observed. These occasionally showed a tree-like appearance, resembling immature Ruffini endings; slowly adapting mechanoreceptors. The present results indicate that periodontal mechanoreceptors are among the main targets of injury-evoked NPY following IAN injury.
Afferent Pathways↗
Formation of odontoblast-like cells from cultured human dental pulp cells on dentin in vitro.
Recent characterization of human dental pulp stem cells has shed new light on the understanding of the odontoblastic lineage. The purpose of the study was to characterize human adult dental pulp cells isolated and cultured in vitro and to examine the cell differentiation potential grown on dentin. We observed that some pulp cells isolated with an enzyme-digestion approach proliferated at a similar rate as the immortal cell line NIH 3T3. Population doubling time (PDt) for pulp cells at passage 3 was 22.6 +/- 0.5 hours and for NIH 3T3 was 23.1 +/- 2.3 hours. The pulp cells formed mineral nodules stimulated with dexamethasone or dexamethasone plus 1,25-dihydroxyvitamin D3. Pulp cells, after being seeded onto mechanically and chemically treated dentin surface, appeared to establish an odontoblast-like morphology with a cytoplasmic process extending into a dentinal tubule revealed by scanning electron microscopy analysis. Our data demonstrated the formation of cells with odontoblastic morphologies on existing dentin, suggesting that isolated human pulp stem cells may differentiate into odontoblasts on dentin in vitro.
3T3 Cells↗
Detection of HIV in the dental pulp of a patient with AIDS.
Dental pulp tissue from a patient with acquired immune deficiency syndrome (AIDS) was examined to determine the presence of the human immunodeficiency virus (HIV). The results found a high concentration of proviral HIV DNA.
Acquired Immunodeficiency Syndrome↗
A comparison of the alkaline phosphatases of rat dental pulp, bone, kidney, liver and intestine.
The sensitivity of the dental pulp enzyme to heat was similar to that of enzymes from bone and kidney; alkaline phosphatases from liver and intestine were more stable to heat. L-Homoarginine strongly inhibited the enzyme activities from pulp, bone, kidney and liver but did not affect intestinal enzyme activity. Increasing the molarity of carbonate buffer or glycine buffer in the assay solution decreased intestinal alkaline phosphatase activity more markedly than enzyme activities of other tissues. In 100 mM glycine-NaOH buffer, the effects of Zn2+, Mg2+ and Ca2+ on pulp alkaline phosphatase activity were similar to those on the enzyme activities of bone, kidney and liver. The electrophoretic pattern of the pulp enzyme on sodium dodecyl sulphate-gels was identical with that of bone enzyme and differed from the patterns of enzymes from other tissues. These results suggest that the dental pulp alkaline phosphatase may be the same as bone enzyme.
Alkaline Phosphatase↗
[Studies on the influence of composite resin filling material (Command Ultra fine) on the dental pulp].
Studies on the influence of composite resin filling material on the dental pulp of human 1st premolar are reported in this thesis. An other experiment was carried out on rabbit with the left 1st molar in their lower jaw as subject and the right 1st molar in the lower jaw as a control. In both experiments with human and rabbit, routine operations were performed to prepare the cavities and filled with composite resin material. The human teeth were extracted 21 days afterwards and the rabbit teeth were extracted 7 days afterwards. Edema was found in the dental pulp of both human and rabbit teeth by pathologic examination and was accompanied by hemangiectasis and lymphaniectasis. There was also vacuolar degeneration in the odontoblasts. Some of these cells were reticulated and the of number of odontoblasts was fewer than in the control. Hemangiectasis was even more serious in the rabbit's teeth than those of human.
Animals↗
Effects of local anesthetics on the respiratory activity in vitro of cells in the dental pulp.
The respiratory activity of isolated dental pulps from rat incisors was studied using a Gilson respirometer. The activity was compared with activities after administration of varying concentrations of commercial standard solutions of lidocaine with and without adrenaline and prilocaine with felypressin. Above a 2.5% concentration of the standard solution added to the respiratory medium a significant inhibition was registered.
Anesthetics, Local↗
Lipopolysaccharide stimulates histamine-forming enzyme (histidine decarboxylase) activity in murine dental pulp and gingiva.
To examine the potential role of the histamine-forming enzyme, histidine decarboxylase (HDC), in oral inflammation and disease, we studied HDC activity in oral tissue after induction by bacterial agents. Following injection of E. coli-derived lipopolysaccharide (LPS) into mice, we measured the quantitative changes in HDC activity over time in dental pulp and gingiva. Oral tissue taken from individual mice was insufficient for detecting precise HDC activity, thus, we combined dental pulp or gingival tissues from four mice and assayed them over the course of 24 h. Our results indicate that LPS stimulated marked elevations of HDC activity in dental pulp and gingiva. This increase reached a maximum at 6 h after LPS injection and remained detectable at for least 24 h. Since mast cells are known to produce histamine through a difference mechanism than HDC induction, we compared LPS-induced HDC activity in dental pulp and gingiva to that in ear skin (a tissue rich in mast cells) and liver (a tissues lacking in mast cells). LPS also induced a marked increase in the HDC activity in liver and ear skin at 6 h after LPS injection. By contrast, saline injection had no effect on the HDC activity in any of the four tissues, although basal levels of HDC activity in ear skin was markedly higher than basal HDC activity in the other three kinds of tissues. Still, the relative increase in LPS-induced HDC activity in dental pulp and gingiva were much greater than that in ear skin. Since liver are devoid of mast cells and ear skin is considered the tissue richest in mast cells, the differences in HDC activity between tissues indicates that histamine induced by LPS may be produced by cells other than mast cells through another mechanism of action. These results also suggest that histamine produced in oral tissues in response to bacterial agents such as LPS could be involved in development of pulpitis or gingivitis (periodontitis), the most common diseases in the dental clinic, and that efforts to inhibit HDC activity, which elevates histamine levels in oral tissues, might offer the basis for novel treatment strategies.
Animals↗
Lymphatic vessels in the healthy human dental pulp.
The lymphatic vessels of the dental pulp have been studied in non-carious teeth of young people. A network of lymphatic vessels drains the pulpal tissue. The lymphatic capillaries are characterized by a thin wall with an irregular profile. Cellular projections rise from the endothelial cells. Micropinocytotic vesicles and intercellular adjoining structures are the main mechanisms for the lymph formation. Multivesicular structures, Weibel-Palade bodies and paracrystalline inclusions have been observed.
Child↗
Weibel-Palade bodies and lymphatic endothelium: observations in the lymphatic vessels of normal and inflamed human dental pulps.
The Weibel-Palade bodies, cytoplasmic organelles characterizing endothelial cells, are abundant in lymphatic capillary endothelium of human dental pulp. Their number almost double in the lymphatic vessels of inflamed dental pulps. The data were discussed and compared with others concerning the demonstration of the presence of von Willebrand factor and P-selectin in the Weibel-Palade bodies of lymphatic vessels in mesentery. It is suggested that the increase in the number of Weibel-Palade bodies observed in dental pulp may be connected along with those in the lymphatic vessels to the function that these adhesive molecules play during inflammatory states.
Dental Pulp↗
Vasodilatory effects and coexistence of calcitonin gene-related peptide (CGRP) and substance P in sensory nerves of cat dental pulp.
Substance P (SP)- and calcitonin gene-related peptide (CGRP)-immunoreactivity (-IR) were localized by immunohistochemistry in the same nerve cell bodies in the trigeminal ganglia as well as in nerve terminals of the dental pulp. The distribution of SP- and CGRP-IR nerves were identical in the dental pulp and mainly associated with blood vessels. The level of CGRP-IR in the dental pulp, as measured by radio-immunoassay (RIA), was 1.4 +/- 0.2 pmol g-1 wet wt, which is in the same range as that found for substance P. Local intra-arterial infusion of synthetic CGRP and substance P produced vasodilatation in the dental pulp as measured by both laser Doppler flowmetry and an 125I clearance technique. The CGRP was effective as a vasodilator when infused in the femtomole per minute range, and SP in the picomole range. The effect of CGRP (50 fmol min-1) was 10 times larger when given after SP (15 pmol min-1) than before it. Since the two peptides coexist in the same neurons, it is suggested that they both contribute to the vasodilation seen upon antidromic stimulation of sensory nerves.
Animals↗
p38 Mitogen-activated protein kinase affects transforming growth factor-beta/Smad signaling in human dental pulp cells.
Transforming Growth Factor-beta (TGF-beta) plays an essential role in differentiation of dental pulp cells into odontoblasts during reparative dentine formation. However, the mechanism by which TGF-beta stimulates dental repair remains rather obscure. Human dental pulp cells were used as an in vitro model in the present work. We showed that TGF-beta signaled through mitogen-activated protein kinases (MAPKs), such as ERK1/2 and p38, along with Smad pathway. Distinct pathways exerted different time response. SB203580, a specific p38 MAPK inhibitor, reduced phosphorylation of Smad3, while it slightly enhanced phosphorylation of Smad2. Increased phosphorylation of ERK1/2 and p38 confirmed that SB203580 did not block activation of TGF-beta receptors. In addition, the inhibition of ERK1/2 activity with MEK1/2 inhibitor U0126 increased TGF-beta mediated phosphorylation of Smad3. Our results suggest that p38 affects the phosphorylation of Smad2 and Smad3 differentially during TGF-beta signaling in human dental pulp cells and ERK1/2 might be involved in the process.
Dental Pulp↗
Anaerobic bacterial extracts influence production of matrix metalloproteinases and their inhibitors by human dental pulp cells.
The role of human dental pulp (HDP) cells in extracellular matrix degradation in pulpitis is still unclear. In this study, the effects of sonicated bacterial extracts (SBEs) from Prevotella intermedia, Fusobacterium nucleatum, Porphyromonas endodontalis, and Porphyromonas gingivalis on the balance between the production of matrix metalloproteinases (MMPs) and that of their inhibitors [tissue inhibitors of metalloproteinases (TIMPs)] by HDP cells were examined. HDP cells were treated with SBEs, and their culture media were later harvested. MMP activities and TIMP concentrations were determined by use of independent measurement strategies and sensitive ELISAs. The production of MMP-1 and MMP-2 was accelerated by all SBE. On the other hand, TIMP-1 production was slightly elevated; and TIMP-2 production was markedly inhibited by all of the extracts. SBEs derived from these anaerobic bacteria seemed to affect the acceleration of extracellular matrix degradation activity by HDP cells. These findings suggest that HDP cells stimulated by bacterial byproducts may be involved in the pathogenesis of pulpitis.
Bacteria, Anaerobic↗
Isolated rat dental pulp cell culture and transplantation with an alginate scaffold.
Many studies have been conducted on tissue stem cells in the field of regenerative medicine, and cultured dental pulp mesenchymal cells have been reported to secrete dentin matrix. In the present study we used alginate as a scaffold to transplant subcultured rat dental-pulp-derived cells subcutaneously into the back of nude mice. We found that when beta-glycerophosphate was added to the culture medium, the mRNA of the dentin sialophosphoprotein (DSPP) gene coding dentin sialoprotein (DSP) and dentin phosphoprotein (DPP) was expressed, and an increase in alkaline phosphatase, an early marker of odontoblast differentiation, was also demonstrated. Six weeks after implantation, subcutaneous formation of radiopaque calcified bodies was observed in situ. Immunohistochemical and fine structure studies identified expression of type I collagen, type III collagen, and DSP in the mineralizing transplants, and isolated odontoblast-like cells began to form dentin-like hard tissue formation. Scattered autolyzing apoptotic cells were also observed in the transplants. The study showed that subcultured rat dental-pulp-derived cells actively differentiate into odontoblast-like cells and induce calcification in an alginate scaffold.
Alginates↗
Effects of fluoride on dental pulp of young rabbits.
Fluoride has been adopting as an anticariogenic agent for many years. Many histologic experiments with the effect of fluoride were made on dental hard tissue, but little is known about its effect on dental pulp. We made histopathological tests on dental pulp of rabbits during administration of fluoride. In this study, 24 young New Zealand rabbits aged 7 days were used. The experimental group (N = 20) was given two intraperitoneal injections of sodium fluoride that contained approximately 7 mg F/kg body mass. The control group (N = 4) was injected with an equivalent volume of normal saline. At the thirteenth day after the final injection, the mandibles were collected and processed according to routine histologic methods. Selected sections were stained with hematoxylin and eosin stain. The mandibular incisor pulp was microscopically examined. The following results were obtained. In the experimental group, histopathologic alterations were observed in the pulp, with loss of palisading of the odontoblastic layer. Slightly elongated swollen odontoblasts were found which showed hydropic alterations. Dilatation and hyperemia of blood vessels were also noted. This dose affected deciduous root resorption and changes in secretory ameloblasts; and also appeared to disturb the dental pulp. The present observations of initial reactions in the pulp following intraperitoneal injection of fluoride are considered suitable as a basis for detailed discussion of histopathologic implications.
Animals↗
Measurement of blood perfusion in the dental pulp with laser Doppler flowmetry.
The reproducibility of laser Doppler flowmetry (LDF) in measuring the perfusion of the dental pulp was investigated. A second aim was to establish if the LDF signal from the dental pulp can be influenced by physiological stimuli, e.g. postural changes. A third aim was to apply the technique to clinical measurements of pulp perfusion in patients undergoing orthodontic therapy. A custom splint to position the probe was fabricated for 10 subjects, and measurements of pulpal perfusion in the maxillary six anterior teeth were repeated on eight occasions with the subject seated. Further, measurements of the dental pulp perfusion in one tooth were repeated with the subject in a standing and supine position. Mean perfusion (arbitrary perfusion units) for individual teeth varied from 2.7 for a central incisor to 15.5 for a lateral incisor. Perfusion was greatest for lateral incisors and least for central incisors. Pulpal perfusion was significantly higher in a supine than in a standing or sitting position. Initial clinical experience with LDF encourages further investigation of its potential as a diagnostic tool for determining pulp vitality. Preliminary experimental results suggest that LDF will be a valuable source indicating pulpal response to orthodontic therapy with fixed appliances.
Adolescent↗
Immunohistochemical demonstration of prostaglandins E2, F2 alpha, and 6-keto-prostaglandin F1 alpha in rat dental pulp with experimentally induced inflammation.
Using formalin-fixed and EDTA-decalcified cryostat sections, the immunohistochemical localization of prostaglandin (PG) E2, PGF2 alpha, and 6-keto-PGF1 alpha (a stable metabolite of PGI2) was examined in normal rat and inflamed dental pulp. Inflammation was induced by opening the pulp chamber. There was no immunoreactivity for prostaglandins in normal dental pulp, whereas positivities for PGE2, PGF2 alpha, and 6-keto-PGF1 alpha were demonstrated in the cytoplasm of macrophages and endothelial cells in the inflamed dental pulp. In addition to these cells, numerous pulp cells and odontoblasts existing in the inflamed pulp and its apical noninflamed area also were intensely stained for PGF2 alpha. Such an area with positive cells gradually extended in an apical direction with the progression of inflammation. These findings suggested that PG production from these host cells is involved in development of inflammation of rat dental pulp.
6-Ketoprostaglandin F1 alpha↗