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PubMed1978

Histologic identification of mast cells in human dental pulp.

Previous investigators who attempted to identify mast cells in the dental pulp have used demineralizing or tooth-splitting procedures to obtain their tissue samples. However, Eda and Langeland15 found that the fluorescence of mast cells is destroyed by acid demineralizing agents. On the other hand, tooth splitting may damage the pulp by crushing it with forceps, or cutting and heating it with burs, stones, or discs. In the present study, we used the extirpated pulps from teeth in which endodontic access openings were made by means of high-speed rotary instruments with water spray. Metachromatic staining methods failed to demonstrate mast cells in any of the non-inflamed pulp specimens. Two of the inflamed pulp specimens revealed numerous mast cells which appeared intact and well preserved with no evidence of degranulation. As to the distribution of the mast cells, there was no correlation with the number and types of other inflammatory cells observed. Although several cells present in the specimens examined were suggestive of mast cells, only those cells that revealed definitive metachromasia were included in this study.

Cytoplasmic Granules↗
PubMed2001

Stimulation of dental pulp with simultaneous recording of the jaw opening reflex in the rat.

The processing of nociceptive information in the central nervous system has been analysed in most studies by activation of peripheral nerves. However, the limitation of this method is the simultaneous activation of noxious and inocuous fibers. Nevertheless, the stimulation of the tooth pulp is believed to activate mainly nociceptive fibers which could be the method of choice. On the other hand, the response to nociceptive activation of the dental pulp is easily quantified by the amplitude of the jaw opening reflex, a nocifensive flexion withdrawal reflex. In this protocol we describe a technique to manufacture and implant electrodes in lower incisors of the rat and a method to prepare and insert stainless steel twisted bipolar electrodes to record the electromyographic activity of both digastric muscles, in response to nociceptive dental pulp stimulation. This approach was applied in the study of the analgesic effects of the rat's striatal stimulation.

Animals↗
PubMed1982

Migration of leukocytes in dental pulp in response to plaque bacteria.

Cell material from three different dental plaque bacteria (Actinomyces viscosus, Streptococcus mitis, Actinobacillus actinomycetemcomitans) were studied for their capacity to induce leukocyte migration in the dental pulp of monkeys. Altogether five animals were used to provide 123 teeth for the study. The bacterial test materials were prepared from lyophilized sonicates of pure cultures of respective bacteria mixed with crystalline bovine serum albumin (BSA) 1:1 by weight. Immediately prior to use in the experiment saline was added to render the test material into a paste-like consistency. Buccal Class V cavities were prepared in the monkey teeth leaving a thin remaining wall to the pulp. In these cavities, the test materials were enclosed for a period of 8 h. A set of control cavities received BSA alone. Placement of test and control materials were made before and after depleting the animals of serum complement by repeated injections of Cobra Venom Factor. Histologic examination of pulp tissue specimens showed that materials from two of the bacterial species (A. viscosus, Act. actinomycetemcomitans) consistently induced infiltrations of polymorphonuclear leukocytes in one to several cell layers underneath the test cavity. The material from S. mitis seemed less potent and in 11 of 22 teeth no pulpal reaction was recorded. Inactivation of complement with Cobra Venom Factor did not appear to affect the severity of the pulpal responses.

Animals↗
PubMed1978

Effect of experimentally induced marginal periodontitis and periodontal scaling on the dental pulp.

Experimental breakdown of the periodontal attachment apparatus was produced in six young adult monkeys to study the effect on the tissue of the dental pulp by (1) periodontitis, (2) scaling and plaque accumulation on exposed root dentin. Periodontal tissue breakdown was induced by the placement of ligatures around the neck of 92 permanent teeth. Subsequent plaque formation caused marked loss of periodontal tissue support, which after a period of 5--7 months amounted to 30--40% of the root length. One group of teeth received no further treatment. Other teeth were subjected to scaling and root planing. Following treatment, plaque was allowed to accumulate for 2, 10, and 30 days on the freshly planed root dentin surfaces. Histologic examination revealed that in comparison to teeth with normal periodontal conditions, 57% of the teeth exposed to periodontitis exhibited pathologic pulp tissue alterations. Secondary dentin formation and/or inflammatory cell infiltrates were observed within localized areas of the pulp subjacent to root surfaces exposed to periodontal tissue destruction. The changes within the pulp were of "mild" nature and only one tooth displayed signs of total pulp necrosis. Lateral canals communicating with both the pulp cavity and the exposed root surface were never detected. Teeth subjected to scaling and subsequent plaque accumulation in comparison with teeth with periodontitis alone exhibited no obvious aggravation or increased incidence of pathologic pulp reactions. The findings show that in the monkey (1) periodontal destruction limited to the cervical half of the root and (2) plaque accumulation on exposed root dentin does not cause severe alteration in the pulp of the roots involved.

Animals↗
PubMed1982

Some properties of monoamine oxidase and a semicarbazide sensitive amine oxidase capable of the deamination of 5-hydroxytryptamine from porcine dental pulp.

The deamination of 5-hydroxytryptamine, tryptamine and benzylamine by porcine dental pulp membrane preparations is brought about not only by monoamine oxidase, but also by a clorgyline (and deprenyl) resistant), semicarbazide sensitive enzyme. The semicarbazide sensitive enzyme was also inhibited by aminoguanidine, hydroxylamine and phenylhydrazine, but was not affected to any significant extent by incubation at 50 degrees for up to 100 min. There was, on the other hand, considerable inhibition of monoamine oxidase activity after incubation at this temperature. The semicarbazide sensitive enzyme neither metabolised, nor was inhibited by putrescine or cadaverine. Mixed substrate experiments indicated that 5-hydroxytryptamine and tryptamine interacted at the same catalytic centre on the semicarbazide sensitive enzyme.

Amine Oxidase (Copper-Containing)↗
PubMed1977

Effect of some heavy metals on protein and collagen biosynthesis in rabbit dental pulp in vitro.

Cadmium, zinc, copper, and mercury, being components of dental alloys, have been tests at concentrations from 20 to 120 micronM for their effect on the incorporation of 14C-proline into various fractions of rabbit dental pulp incubated in vitro. With cadmium and zinc and increased amount of 14C-activity was recovered from the TCA-soluble pool, whereas the further incorporation into total protein and collagen, i.e. 14C-hydroxyproline, was markedly inhivited. Copper and mercury, however, reduced the amount of label in the TCA-soluble fraction. Both metals exhibited a dose-dependent inhibitory effect on the hydroxylation step in collagen synthesis, whereas for mercury only, an inhibition of the general protein synthesis was indicated. With all four metals the proportion of 14C-labeled protein and hydroxyproline recovered from the medium was reduced, the effect being most prominent with cadmium and zinc.

Animals↗
PubMed1993

Scanning electron microscopic observation of the vascular wall cells in human dental pulp.

The following six vascular segment types were identified in human dental pulp based on morphological differences in the periendothelial cells: (a) muscular arterioles with at least two compact layers of smooth muscle (SM) cells; (b) terminal arterioles with at least one compact muscle layer; (c) precapillary arterioles with an incomplete muscle layer; (d) capillaries with scattered pericytes; (e) postcapillary venules with clustered pericytes; and (f) muscular venules with at least one layer of flattened SM cells. In almost all muscular and terminal arterioles, the surface of SM cells showed marked to slight irregularities indicating vasoconstriction apparently caused by local administration of anesthetic containing epinephrine. Flattened SM cells in muscular venules also showed surface irregularities. SM cells in precapillary arterioles and pericytes in capillaries and most postcapillary venules, however, showed no distinct features of constriction.

Adolescent↗
PubMed2005

Substance P activates p38 mitogen-activated protein kinase to promote IL-6 induction in human dental pulp fibroblasts.

Substance P (SP) induces the expression of proinflammatory cytokines, such as interleukin (IL)-6, which are implicated in pulp inflammation. To determine the signal pathway of SP-induced IL-6, we examined the activities of the mitogen-activated protein kinases (MAPKs) in human dental pulp cell (PF-10) cultures. SP induced the phosphorylation of p38 MAPK within 5 min; this activation persisted for up to 40 min and was independent of the activation of extracellular signal-related kinases (ERK-1 and ERK-2) that were induced after SP stimulation of PF-10 cells. As shown by electrophoretic mobility shift assay p38 MAPK was not involved in SP-induced activation of nuclear factor-kappa B (NF-kappaB). However, p38 MAPK mediated SP-induced IL-6 production, as shown by the use of specific inhibitors of this kinase. Our results suggest that the activation of p38 MAPK is important for NF-kappaB-independent regulator of neurogenic inflammation in dental pulp tissues.

Adult↗
PubMed1998

Gender determination from dental pulp by using capillary gel electrophoresis of amelogenin locus.

Gender of dental pulp DNA was determined by the capillary gel electrophoresis (CGE) method with amelogenin locus as a marker. The analysis of the male sample resulted in two peaks, a Y-locus standard sample was added and the CGE method repeated. This resulted in an amplification of the second peak and judging from the difference between the allele sizes of the X and Y loci, it was confirmed that the first peak was for the X and the second for the Y locus. The female sample was then analyzed and one peak was observed. As before the X-locus standard sample was added to this sample and resulted in an amplification of the peak, thus verifying it to be the X locus. The CGE method was conducted for 10 male and 10 female samples and double peaks verified the male sample, while one peak verified the female sample. Gender was thus correctly determined in all cases.

Amelogenin↗
PubMed1979

Fine structural observations of calcium storage in human dental pulp cells in primary culture.

Primary culture of explants of human dental pulp tissue allows the study of the cytophysiology and differentiation of the cultured cells over a two-week period. The distribution of calcium was found in two different experimental conditions : with and without a calcium loading, by mean of a lead technique checked by microprobe analysis. The existence of two cell populations was revealed. Intra-mitochondrial ring-like granules characterize type 1 cells when overloaded, while a strong calcium storage is detected in the rough endoplasmic reticulum, Golgi apparatus and mitochondrial (without any inner organization of the deposits) of the type 2 cells. Our results also show the presence of calcium on gap-junctions (revealed) by lanthanum method), and on the extracellular matrix (collagen fibres and complex carbohydrates). The ability of some mitochondria to store calcium (ring-like granules) suggests that the type 1 cells are fully differentiated in odontoblast-like cells and perhaps engaged in mineralization processes. The calcium binding sites, localized on the extracellular matrix may therefore be considered as the earliest foci of calcification.

Calcium↗
PubMed2003

Responses of rat trigeminal neurones to dental pulp cells or fibroblasts overexpressing neurotrophic factors in vitro.

The adult dental pulp is innervated by sensory trigeminal axons and efferent sympathetic axons. Rat trigeminal ganglia extend neurites when co-cultivated in vitro with pulpal tissue explants, suggesting that pulpal cells secrete soluble molecules that stimulate the growth of trigeminal ganglion axons. In addition, cultured pulpal cells produce mRNAs for neurotrophins and glial cell line-derived neurotrophic factor-family members. These data suggest that neurotrophic factors are involved in the formation of a pulpal innervation. Here, we examine how pulpal cells and 3T3 fibroblasts overexpressing certain neurotrophic factors (nerve growth factor, brain-derived neurotrophic factor, neurotrophin-3, neurotrophin-4, glial cell line-derived neurotrophic factor or neurturin) influence survival and growth of single trigeminal ganglion neurones in vitro in quantitative terms. The results show that most of the neurotrophic factor-overexpressing fibroblasts induce similar neuronal soma diameters, but higher survival rates and neurite lengths compared with pulpal cells. With respect to neurite growth pattern, trigeminal ganglion neurones co-cultured with fibroblasts overexpressing nerve growth factor develop a geometry that is most similar to that seen in co-cultures with pulpal cells. We conclude that none of the fibroblasts overexpressing neurotrophic factors can fully mimic the effects of pulpal cells on trigeminal ganglion neurones, and that nerve growth factor promotes a neurite growth pattern most similar to the picture seen in co-cultures with pulpal cells.

3T3 Cells↗
PubMed2005

Molecular and biomechanical characterization of mineralized tissue by dental pulp cells on titanium.

The application of implant therapy is still limited, because of various risk factors and the long healing time required for bone-titanium integration. This study explores the potential for osseointegration engineering with dental pulp cells (DPCs) by testing a hypothesis that DPCs generate mineralized tissue on titanium. DPCs extracted from rat incisors positive for CD44, alkaline phosphatase activity, and mineralizing capability were cultured on polystyrene and on machined and dual-acid-etched (DAE) titanium. Tissue cultured on titanium with a Ca/P ratio of 1.4 exhibited plate-like morphology, while that on the polystyrene exhibited fibrous and punctate structures. Tissues cultured on titanium were harder than those on polystyrene, 1.5 times on the machined and 3 times on the DAE. Collagen I, osteopontin, and osteocalcin genes were up-regulated on titanium, especially the DAE surface. In conclusion, DPCs showing some characteristics of the previously identified dental pulp stem cells can generate mineralized tissue on titanium via the osteoblastic phenotype, which can be enhanced by titanium surface roughness.

Acid Etching, Dental↗
PubMed2002

Matrix metalloproteinase levels and gelatinolytic activity in clinically healthy and inflamed human dental pulps.

The role of matrix metalloproteinases (MMPs) in the breakdown of pulp tissue of teeth with severe caries has not yet been directly elucidated. This study was to determine the levels of selected MMPs and the overall gelatinolytic activity in clinically healthy and inflamed human dental pulps of 29 healthy subjects, aged 10-19 yr. Seventeen pulps were collected from subjects diagnosed with symptomatic pulpitis, and 18 control pulps were obtained from 12 subjects following premolar extraction for orthodontic reasons. The levels of MMP-1, MMP-2, MMP-3 and MMP-9 were determined with enzyme-linked immunosorbent assay. Densitometric analysis of gelatin zymograms was used to assay gelatinolytic activity in pulp supernatants. The MMP-1 levels were below the detection limit for both groups. Levels of MMP-2 and MMP-3 were significantly lower in symptomatic vs. clinically healthy pulps. In contrast, levels of MMP-9 in inflamed pulps were significantly higher than those recorded in clinically normal pulps. The overall gelatinolytic activity was elevated in inflamed pulps compared with healthy counterparts. Further, the gelatinolytic activity was positively correlated with MMP-9 levels. The data obtained suggest a key role of MMP-9 in the breakdown of inflamed human dental pulp tissue.

Adolescent↗
PubMed1979

The effects of etching enamel with acid on human dental pulp. A preliminary study.

Enamel acid-etching has become a widespread, popular clinical procedure in recent years. Numerous studies have investigated the nature of the acid-treated enamel. However, little or no information is presently available pertaining to the effects of acid treatment upon dental pulp tissue. A limited investigation was carried out on bilateral orthodontic extraction cases to determine the effects of enamel acid-etching upon healthy dental pulp. In each of five cases one premolar served as the experimental tooth, while the contralateral premolar served as the control. After a 24-hour postoperative interval there appeared to be no basic histologic difference between the experimental and control groups.

Acid Etching, Dental↗
PubMed1990

[Thermal effects in the dental pulp caused by laser radiation from various laser types].

In this in vitro study the temperature rises occurring in the dental pulp during laser irradiation were measured. Infrared laser radiation (CO2 and Nd: YAG) had great thermal effects on the pulp tissues. At an average power output level of 5 W temperature rises of approx. 40 degrees C within 100 s were observed. The effect of a cooling system was negligible. Radiation from an ArF excimer laser (193 nm) at an average output of 5 W caused only slight thermal changes, when an airstream was used to remove the fragments of photoablative decomposition of the dental tissues. The temperature in the pulp chamber increased by approx. 5 degrees C after 6 min. This result leads to the conclusion that only ArF excimer lasers may be effectively used in the mouth without producing inacceptable thermal effects in the dental pulp.

Dental Pulp↗
PubMed2005

Multipotent mesenchymal stem cells with immunosuppressive activity can be easily isolated from dental pulp.

BACKGROUND: Bone marrow mesenchymal stem cells (MSCs) are currently being investigated in preclinical and clinical settings because of their multipotent differentiative capacity or, alternatively, their immunosuppressive function. The aim of this study was to evaluate dental pulp (DP) as a potential source of MSCs instead of bone marrow (BM). METHODS: Flow cytometric analysis showed that DP-MSCs and BM-MSCs were equally SH2, SH3, SH4, CD29 and CD 166 positive. The in vitro proliferative kinetics of MSCs were measured by 3H-thymidine incorporation uptake. The immunosuppressive function of MSCs was then tested by coculturing PHA-stimulated allogeneic T cells with or without MSCs for 3 days. RESULTS: BM-MSCs could be differentiated in vitro into osteogenic, chondrogenic and adipogenic lineages. DP-MSCs showed osteogenic and adipocytic differentiation, but did not differentiate into chondrocytes. Although DP-MSCs grow rapidly in vitro between day 3 and day 8 of culture and then decrease their proliferation by day 15, BM-MSCs have a stable and continuous proliferation over the same period of time. The addition of DP-MSCs or BM-MSCs resulted in 91 +/- 4% and 75 +/- 3% inhibition of T cell response, respectively, assessed by a 3H-thymidine assay. CONCLUSIONS: Dental pulp is an easily accessible and efficient source of MSCs, with different kinetics and differentiation potentialities from MSCs as isolated from the bone marrow. The rapid proliferative capacity together with the immunoregulatory characteristics of DP-MSCs may prompt future studies aimed at using these cells in the treatment or prevention of T-cell alloreactivity in hematopoietic or solid organ allogeneic transplantation.

Adult↗