Healthy Human Dental Pulp Research Articles

The Effect of Cavity Preparation on Substance P Expression in Human Dental Pulp

Abstract Substance P (SP) plays an important role during neurogenic inflammation of dental pulp. The purpose of this study was to use a radioimmunoassay for determining the effect of cavity preparation on SP expression in healthy human dental pulp. Ten pulp samples were obtained from healthy premolars where extraction was indicated for orthodontic reasons. Deep cavity preparation (<1 mm remaining dentine thickness) was performed before extraction in five of these bicuspids. All samples were processed and 125I-SP labeled; SP was quantified by competition assay. The results revealed SP expression in all human pulp samples. Mann-Whitney’s U test revealed statistically significant higher expression in pulp from teeth where cavity preparation had been performed compared to control values (p < 0.05). These findings suggest that SP is released during common dental procedures (such as cavity preparation) and its expression may have an important clinical significance in terms of experiencing inflammation and pain.

Copper–zinc superoxide dismutase activity in healthy and inflamed human dental pulp

To examine copper-zinc superoxide dismutase (Cu, Zn-SOD) activity in clinically healthy and symptomatic human dental pulps. Twenty-five systemically healthy patients, 14 females and 11 males (age: 13.1-34.6 years; mean: 21.7 +/- 6.3), were the source of the pulp tissue. The condition of the pulps was assessed using clinical and radiographic evaluation. The pulp tissue was collected by longitudinally grooving and splitting the teeth (if extracted) or during endodontic treatment, and were age- and sex-matched between the healthy and the irreversible symptomatic pulpitis tissue groups. Cu, Zn-SOD activity was determined through spectrophotometric methods and a Mann-Whitney test assessed the significance of differences between the groups. The enzyme activities were 144.8 +/- 42.2 and 68.1 +/- 25.0 U mg(-1) in the healthy and irreversible symptomatic pulp tissue, respectively. The difference between the groups was statistically significant (P < 0.001). These results demonstrate a potential role for Cu, Zn-SOD during dental pulp inflammation in humans.

Three-dimensional wall structure and the innervation of dental pulp blood vessels.

The involvement of neural components in plasma extravasation and blood flow in the dental pulp has been established by pharmacological and physiological studies. We review here the segmental constitution of pulp vessels and the possible involvement of neural components in both the contractility and permeability of the pulp vessels from a morphological viewpoint. Six vascular segments can be identified based on the morphology of peri-endothelial cells, such as smooth muscle cells and pericytes. These are: muscular arterioles, terminal arterioles, precapillary arterioles, capillaries, postcapillary venules, and collecting or muscular venules. The perivascular nerve forms a mesh with numerous terminal varicosities, some of which attach directly to arteriolar smooth muscle cells. This mesh can be seen by scanning electron microscopy, and indicates the important role of neural components in regulating the pulpal circulation. After administering norepinephrine (0.2 mg/kg/dog), the surface texture of the smooth muscle cells of pulp arterioles reveals marked irregularities, which are correlated with arteriolar contraction. The pericytes in larger postcapillary venules (diameter 20 microm or larger) also show irregularities, whereas no changes are seen in the pericytes of either smaller postcapillary venules or capillaries. The intercellular spaces of pericytes in the postcapillary venules are wide enough for leukocytes to pass through, and the occasional extravasation of leukocytes through venule walls can be seen under electron microscopy. The microvessels of healthy human dental pulp react weakly to selectins, indicating that apparently healthy dental pulp may be weakly inflamed. In rat dental pulp, CGRP-immunoreactive nerves and nerve terminals containing many granular vesicles supply the postcapillary venules more densely than the arterioles, which suggests the involvement of postcapillary venules in neurogenic inflammation in the dental pulp.

Aspartate Aminotransferase Activity in Human Healthy and Inflamed Dental Pulps

Aspartate aminotransferase (AST) seems to be an important mediator of inflammatory processes. Its role in the progression and detection of inflammatory periodontal disease has been increasingly recognized in recent years. In the present study AST activity was analyzed in normal healthy human dental pulps, in reversible pulpitis, and in irreversible pulpitis. Enzymatic AST activity showed that the control values for the healthy pulps were 4.8 +/- 0.7 units/mg of pulp tissue. In reversible pulpitis specimens the AST activity increased to 7.98 +/- 2.1 units/mg of pulp tissue. In irreversible pulpitis specimens the values decreased to 2.28 +/- 1.7 units/mg of pulp tissue. Differences between the groups (control versus reversible pulpitis and reversible pulpitis versus irreversible pulpitis) were statistically significant (p = 0.0015). These results could point to a role of AST in the early events that lead to development of pulpal inflammation.

Alkaline Phosphatase Activity in Normal and Inflamed Dental Pulps

Alkaline phosphatase (ALP) seems to be important in the formation of mineralized tissues. High levels of ALP have been demonstrated in dental pulp cells. In the present study ALP activity was analyzed in normal healthy human dental pulps, in reversible pulpitis, and in irreversible pulpitis. Enzymatic ALP control values for the normal healthy pulps were 110.96+/-20.93. In the reversible pulpitis specimens the ALP activity increased almost eight times to 853.6+/-148.27. In the irreversible pulpitis specimens the values decreased sharply to 137.15+/-21.28 and were roughly equivalent to those seen in normal healthy pulps. The differences between the groups (control vs. reversible pulpitis and reversible pulpitis vs. irreversible pulpitis) were statistically significant. These results could point to a role of ALP in the initial pulp response after injury.

Localization of the e-NOS enzyme in endothelial cells and odontoblasts of healthy human dental pulp

Nitric oxide synthases (NOS) are important enzymes present in different cells such as endothelial cells, macrophages, etc. Recently, it has been found that nitric oxide (NO) is responsible for vasodilation, blood pressure regulation, platelet aggregation, cardiac contractility, and the mediation of immunity during bacterial infections and inflammation. However, the production and role of NO in various structures of the oral cavity have not been investigated extensively. The aim of this study was to evaluate the presence of e-NOS in healthy human odontoblasts and endothelial cells of the dental pulp. Twenty healthy human dental pulps were collected and frozen and pulp slices were obtained using a cryostat. The e-NOS enzyme was revealed by immunohistochemical analysis and the enzyme level was detected by Western blotting and mRNA expression by RT-PCR. The immunohistochemical results demonstrated, for the first time, the presence of e-NOS in odontoblasts and in endothelial cells. The presence of e-NOS m-RNA was confirmed by RT-PCR and the expression of the protein by Western blotting. These results clearly show that the e-NOS enzyme is present in both odontoblasts and endothelial cells of healthy human pulp. The presence of e-NOS in the odontoblast and endothelial cells of the dental pulp may mediate local vasodilation and cell proliferation.

The presence of pericytes and transitional cells in the vasculature of the human dental pulp: an ultrastructural study.

The aim of this study was to determine the ultrastructural characteristics of the microvasculature of healthy human dental pulp, with particular reference to pericytes. Pulp tissue was taken from healthy impacted third molars following extraction. Eight teeth were obtained from 17- to 25-year-old patients and pulp tissue was processed for examination using standard techniques for transmission electron microscopy. The pulp was rich in capillaries composed of endothelial and peri-endothelial cells in a 4: 1 ratio. Endothelial cells contained typical and abundant Weibel-Palade bodies. Three types of peri-endothelial cells were identified: pericytes, transitional cells and fibroblasts. Pericytes were embedded within the capillary basement membrane. Transitional cells were partly surrounded by basement membrane, but separated from the endothelium by collagen fibrils; fibroblasts were outside, but adjacent to the basement membrane and closely associated with collagen fibrils. Pericytes and transitional cells, but not peri-endothelial fibroblasts, contained low numbers of dense bodies similar to the endothelial Weibel-Palade bodies. Our observations are consistent with the hypothesis that, during normal tissue turnover, some pericytes may originate from endothelium and migrate away from the vessel wall to undergo transition to a fibroblastic phenotype.

Vascular endothelium of human dental pulp expresses diverse adhesion molecules for leukocyte emigration

The expression of adhesion molecules on the vascular endothelium of healthy and inflamed human dental pulp was studied immunohistochemically using antibodies for selectin family and immunoglobulin superfamily members. In healthy dental pulp, some vessels reacted very weakly with major histocompatibility complex (MHC) class II, and E- and P-selectin, and many vessels reacted with platelet-endothelial cell adhesion molecule-1 (PECAM-1), but no vessels reacted with intercellular adhesion molecule-1 (ICAM-1), ICAM-3 and vascular cell adhesion molecule-1 (VCAM-1). In inflamed pulp, a large number of vessels reacted strongly with MHC class II, E- and P-selectin, PECAM-1, ICAM-1, ICAM-3, and VCAM-1. This indicates that the vascular endothelium of the inflamed human dental pulp expresses diverse adhesion molecules for leukocyte emigration from the blood stream into tissue. Dental pulp is surrounded by dentin and isolated from other tissue, like an in vitro system, so dental pulp is an attractive model for studying the roles of adhesion molecules on the vascular endothelium in transendothelial migration of leukocytes.

Isolation and characterization of the proteoglycans synthesized by adult human pulp fibroblasts in vitro.

The proteoglycans synthesized by fibroblasts derived from healthy human adult dental pulps have been isolated and characterized on the basis of their glycosaminoglycan content, molecular size and charge. The proteoglycans were identified by their labelling with [35S] sulphate and susceptibility to digestion by papain. The sulphated glycosaminoglycans associated with the proteoglycans were identified following specific enzymatic and chemical degradations as chondroitin sulphate, dermatan sulphate and heparan sulphate. Dermatan sulphate and chondroitin sulphate and heparan sulphate were the principal glycosaminoglycans associated with the cell layers. The proteoglycans could be fractionated on the basis of their charge and size into a number of heterogeneous pools. The principal proteoglycans isolated were small and contained either chondroitin sulphate or dermatan sulphate and most likely correspond to decorin and biglycan. Other molecules with features similar to versican and syndecan were also identified.

RS 52 Evaluation of the concentrations of ICAM-1 in healthy and inflamed human dental pulp

RS 52 Evaluation of the concentrations of ICAM-1 in healthy and inflamed human dental pulp

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.

Identification of lymphocyte antigens in human dental pulps

The aim of the experiment was to study the immune reaction of cells in both healthy and inflamed human dental pulps. For this it was necessary to identify, in particular, populations of lymphocytes in the pulp, and also other cells involved in the immune reaction. By using monoclonal antibodies which specifically recognize subpopulations of the T lymphocytes, we were able: 1) to directly determine the phenotype of the cells of the pulp, 2) to examine the interactions of the different cell populations. The study was based on 30 permanent human dental pulps and the method was that of indirect immunofluorescence on frozen sections. The monoclonal antibodies used were the antibodies OKT and anti-Leu of types anti-Leu1, anti Leu3a, OKT4, OKT8 and OK1a. The results obtained were evaluated statistically. Two important points stand out from this study: 1) in the healthy samples there is preferential localization of lymphocytes at the periphery of the pulp and 2) there is a predominance of the OKT8+ cytotoxic suppressor subpopulation in both the healthy and the inflamed pulps.