Human Pulp Tissue Research Articles

Cytotoxicity and Bioactivity of Dental Pulp-Capping Agents towards Human Tooth-Pulp Cells: A Systematic Review of In-Vitro Studies and Meta-Analysis of Randomized and Controlled Clinical Trials.

Background. In the era of biology-driven endodontics, vital pulp therapies are regaining popularity as a valid clinical option to postpone root-canal treatment. In this sense, many different materials are available in the market for pulp-capping purposes. Objectives. The main aim of this systematic review and meta-analysis was to examine literature regarding cytotoxicity and bioactivity of pulp-capping agents by exposure of human dental pulp cells of primary origin to these materials. A secondary objective was to evaluate the inflammatory reaction and reparative dentin-bridge formation induced by the different pulp-capping agents on human pulp tissue. Data sources. A literature search strategy was carried out on PubMed, EMBASE and the Web of Science databases. The last search was done on 1 May 2020. No filters or language restrictions were initially applied. Two researchers independently selected the studies and extracted the data. Study selection included eligibility criteria, participants and interventions, study appraisal and synthesis methods. In vitro studies were included when human dental pulp cells of primary origin were (in) directly exposed to pulp-capping agents. Parallel or split-mouth randomized or controlled clinical trials (RCT or CCT) were selected to investigate the effects of different pulp-capping agents on the inflammation and reparative bridge-formation capacity of human pulp tissue. Data were synthesized via odds ratios (95% confidence interval) with fixed or random effects models, depending on the homogeneity of the studies. The relative risks (95% confidence interval) were presented for the sake of interpretation. Results. In total, 26 in vitro and 30 in vivo studies were included in the systematic review and meta-analysis, respectively. The qualitative analysis of in vitro data suggested that resin-free hydraulic calcium-silicate cements promote cell viability and bioactivity towards human dental pulp cells better than resin-based calcium-silicate cements, glass ionomers and calcium-hydroxide cements. The meta-analysis of the in vivo studies indicated that calcium-hydroxide powder/saline promotes reparative bridge formation better than the popular commercial resin-free calcium-silicate cement Pro-Root MTA (Dentsply-Sirona), although the difference was borderline non-significant (p = 0.06), and better than calcium-hydroxide cements (p < 0.0001). Moreover, resin-free pulp-capping agents fostered the formation of a complete reparative bridge better than resin-based materials (p < 0.001). On the other hand, no difference was found among the different materials tested regarding the inflammatory effect provoked at human pulp tissue. Conclusions. Calcium-hydroxide (CH) powder and Pro-Root MTA (Dentsply-Sirona) have shown excellent biocompatibility in vitro and in vivo when tested on human cells and teeth. Their use after many years of research and clinical experience seems safe and proven for vital pulp therapy in healthy individuals, given that an aseptic environment (rubber dam isolation) is provided. Although in vitro evidence suggests that most modern hydraulic calcium-silicate cements promote bioactivity when exposed to human dental pulp cells, care should be taken when these new materials are clinically applied in patients, as small changes in their composition might have big consequences on their clinical efficacy. Key findings (clinical significance). Pure calcium-hydroxide powder/saline and the commercial resin-free hydraulic calcium-silicate cement Pro-Root MTA (Dentsply-Sirona) are the best options to provide a complete reparative bridge upon vital pulp therapy. Systematic review registration number. PROSPERO registration number: CRD42020164374.

Dental pulp stem cells from human teeth with deep caries displayed an enhanced angiogenesis potential in vitro

Background/purposeDental pulp stem cells can be isolated from human teeth with deep caries (cDPSCs), but their biological characteristics are still unclear. The aim of this study was to investigate the angiogenic potential of cDPSCs and compare them to dental pulp stem cells from human normal teeth (nDPSCs). Materials and methodsCells were isolated from human pulp tissue of normal and infected teeth with deep caries. Basic mesenchymal stem cell (MSC) characterization was conducted. Colony forming units and proliferation ability were evaluated in nDPSCs and cDPSCs. Expression of VEGF in both tissues and cells was examined by immunohistochemical staining. After stimulating nDPSCs and cDPSCs with an angiogenic medium, angiogenic markers were evaluated by qRT-PCR and western blotting. Finally, tube formation assays were used to evaluate the in vitro angiogenesis potential of both cell populations. ResultsBoth nDPSCs and cDPSCs possessed typical MSC characteristics. cDPSCs had enhanced colony formation and proliferation capacities than nDPSCs did. The expression of VEGF was higher in pulp tissue from teeth with deep caries and cDPSCs than in normal tissue and nDPSCs. When both cell types were grown in vitro under angiogenic conditions, cDPSCs expressed a higher level of angiogenic markers and showed a stronger angiogenesis potential than nDPSCs did. ConclusioncDPSCs maintained MSC traits and presented a higher angiogenesis potential than nDPSCs.

Human pulp tissue dissolution ability of different extracts of Sapindus mukorossi: An in vitro study

ObjectiveDue to the many negative properties of sodium hypochlorite used in current root canal treatment, interest in biocompatible natural agents is increasing day by day. The aim of this study was to evaluate whether various extract solutions of Sapindus mukorossi have dissolution effects on human pulp tissues. MethodsPrimarily powder extracts were obtained by extracting fruit shells of S. mukorossi in different solvents (ethanol, methanol, buthanol and distilled water). The test solutions were prepared and randomly separated into six groups with 10 samples in each group: ethanol extract, methanol extract, butanol extract, distilled water extract of S. mukorossi, sodium hypochlorite (NaOCl) and the control group. Among these, S. mukorossi extracts were separated into two subgroups, depending on their concentration level (50 µg/mL and 100 µg/mL). The pulp tissues of freshly extracted human molars were used for dissolution test. The weights of the pulpal tissues were measured and recorded for two times after the samples were placed in the solutions. Statistical analysis for all descriptive statistics was performed using SPSS 22 (P < 0.05). ResultsOur results showed that maximum percent yield of preparation was obtained in methanol extract of S. mukorossi. Among all of the groups, the best dissolution capacity was seen in the NaOCl group (positive control group). Among S. mukorossi groups, the best tissue solvent solution was found in SMM group at 50 µg/mL and SMB group at 100 µg/mL. ConclusionThe different extracts of S. mukorossi had a capacity to dissolve pulp tissue but this capacity was less than NaOCl. Therefore, further studies will enable the creation of a commercial solution for clinical use by increasing the effectiveness of S. mukorossi while combining it with other endodontic irrigation solutions.

Highly Proliferative Immortalized Human Dental Pulp Cells Retain the Odontogenic Phenotype when Combined with a Beta-Tricalcium Phosphate Scaffold and BMP2.

Human dental pulp cells (HDPCs) play a vital role in dentin formation and reparative dentinogenesis, which indicated their potential application in regenerative medicine. However, HDPCs, which can only be obtained from scarce human pulp tissues, also have a limited lifespan in vitro, and stem cells usually lose their original characteristics over a large number of passages. To overcome these challenges, we successfully immortalized human dental pulp cells using the piggyBac system which was employed to efficiently overexpress the SV40 T-Ag, and we then comprehensively described the cell biological behavior. The immortalized human dental pulp cells (iHDPCs) acquired long-term proliferative activity and expressed most HDPC markers. The iHDPCs maintained multiple differentiation potential and could be induced to differentiate into chondrogenic, osteogenic, and adipogenic cells in vitro. We also proved that the iHDPCs gained a stronger ability to migrate than the primary cells, while apoptosis was inhibited. Furthermore, highly proliferative iHDPCs displayed no oncogenicity when subcutaneously implanted into athymic nude mice. Finally, iHDPCs exhibited odontogenic differentiation ability and secreted dentin sialophosphoprotein (DSPP) when combined with a beta-tricalcium phosphate scaffold and bone morphogenetic protein-2 (BMP2) in vivo. Conclusively, the established iHDPCs are a valuable resource for mechanistic study of dental pulp cell differentiation and dental pulp injury repair, as well as for applications in tooth regeneration.

Histologic Response of Human Pulp and Periapical Tissues to Tricalcium Silicate–based Materials: A Series of Successfully Treated Cases

Pulpal/periapical responses of human teeth that are treated successfully with tricalcium silicate–based materials are extremely difficult to obtain because of the typical unavailability of these teeth for histologic examination. The present case series reports histologic and histobacteriologic findings of 3 human teeth that had undergone pulpotomy, orthograde retreatment, and apicoectomy/root-end filling using tricalcium silicate–based endodontic materials. The teeth were extracted after 34 days, 7 weeks, and 20 months, respectively, because of unusual circumstances. The extracted teeth were processed, paraffin embedded, sectioned, stained with hematoxylin-eosin or the modified Brown and Brenn technique, and examined with light microscopy. The recurrent observation for the 3 cases presented was the absence of inflammatory or foreign body reactions of the host tissues in contact with tricalcium silicate–based materials after different observation periods despite the identification of bacteria in dentinal tubules close to the site of operation. Wound healing was rapid with repair/regeneration of lost tissues with cementum and new bone trabeculae. Although the level of evidence for a case series is low because of the anecdotal nature of the reported episodes, the histologic results reported in the present case series illustrate the highly biocompatible and bioactive nature of the tricalcium silicate–based materials used in treating these cases.

Lipopolysaccharide-induced DNA damage response activates nuclear factor κB signalling pathway via GATA4 in dental pulp cells.

To investigate the role of GATA-binding protein 4 (GATA4) in the inflammatory response induced by DNA double-strand breaks (DSBs) in human dental pulp cells (hDPCs). Lipopolysaccharide (LPS) was used for stimulating inflammation in dental pulp tissue in vivo and hDPCs in vitro. Expression levels of GATA4 and γ-H2A.X (a marker for DSBs) were detected at different stages of pulpitis in a rat model and human pulp tissues by immunohistochemistry. Real-time quantitative polymerase chain reaction and Western blot were performed to assess expression of GATA4 and γ-H2A.X and the activation of nuclear factor κB (NF-κB) in hDPCs stimulated by LPS. The comet assay was used for detecting the extent of DSBs in hDPCs. Immunocytochemistry and Western blot were utilized to evaluate expression of γ-H2A.X and GATA4 and activation of NF-κB in hDPCs pre-treated with inhibitors of DNA damage response or transfected with GATA4 small interfering RNA before the treatment of LPS. Data were analysed statistically using one-way anova or Kruskal-Wallis tests. The expression of GATA4 and activation of DNA damage response and NF-κB in inflamed pulp tissue and LPS-treated hDPCs were identified. Significantly decreased expression of GATA4 and significantly decreased inflammatory processes in hDPCs were demonstrated via suppression of DNA damage response (P<0.05). In GATA4-knockdown cells, the expression of γ-H2A.X did not change, but nuclear translocation of p65 was significantly suppressed (P<0.05) upon induction by LPS. Lipopolysaccharide-induced DSBs activated the NF-κB signalling pathway in hDPCs, and GATA4 acts as a positive moderator of the progress. The involvement of GATA4 in this pathology may serve as a therapeutic target in pulpitis.

Human Pulp Fibroblast Implication in Phagocytosis via Complement Activation

IntroductionPrevious works have shown that human pulp fibroblasts synthetize all complement components. Local complement activation in the dental pulp is known to be involved in inflammation and regeneration and also in pathogen destruction through membrane attack complex formation. Bacterial elimination by complement-mediated phagocytosis implies microorganism opsonization with the complement C3b protein, which is recognized by specific phagocytic cell CR1 receptors for subsequent intracellular destruction. This work was designed to find out whether pulp fibroblasts produce C3b and check its subsequent implication in bacteria phagocytosis. MethodsThe expression of C3b was investigated in carious and healthy human pulp tissues. To simulate a bacterial infection in vitro, cultured human pulp fibroblasts were stimulated with lipoteichoic acid, and C3b secretion was quantified by an enzyme-linked immunosorbent assay. C3b fixation on bacteria (opsonization) and the inflammatory THP-1 cell complement receptor 1 was studied by immunofluorescence. A gentamycin protection assay was used to check the implication of C3b secretion by fibroblasts in bacteria phagocytosis. ResultsPulp cells constitutively express C3b in vivo, and cultured pulp fibroblasts produce C3b. We observed a fixation of this C3b protein on the bacterial surface (opsonization) and the THP-1 CR1 receptor. This recognition leads to a significant increase in bacteria phagocytosis. ConclusionsThese results showed that pulp fibroblasts mediate the process of phagocytosis by producing the complement C3b protein and opsonizing bacteria. This highlights a significant role of fibroblasts in the dental pulp local regulation of inflammation.

Inflammatory response of the human tooth pulp tissue to dental caries

Introduction: Dental caries is a chronic infectious disease resultingfrom the penetration of oral bacteria into tooth hard tissues.Microorganisms subsequently trigger inflammatory responsesin the dental pulp and the stem cells provide a source of cells toreplace the damaged cells and facilitate repair. These events canlead to pulp healing if the infection is not too severe and treatedin a short time. Remaining pulpal pathosis in severe form withouttreatment induces permanent loss of normal tissue due to limitedrepair capacities in response to large damage. The importanceof the depth of inflammation has been underestimated in pulpalhealing. The purpose of this study is to investigate the pulp tissueresponse to dental caries and to find out the association of differentdistributions of the inflammatory characteristics among a differentdepth of dental caries. Materials and Methods: Pulp tissue sampleswere collected from 118 extracted teeth from the Privet dental clinicsand dental health centers in Duhok government, from April/ 2016 toAugust/ 2017 (16 months period). Each section prepared and stainedwith hematoxylin and Eosin (H&amp;E). Inflammatory infiltration, fibrosis, calcification, and necrosis were the main features that have beenexamined histopathologically and assessed with the presence of dentalcaries at a different depth. Results and Discussion: Inflammatoryfeatures were identified in 88 of the samples examined. Inflammatory infiltration and fibrosis were the most frequent features amongthe deep caries teeth compared to the shallow caries teeth. Single andgroup of calcification were observed in 57 samples, most of them (48samples) were in deep caries sections. Conclusion: the histopathological observations of pulp tissue in response to caries process provideuseful information for the clinical aspect and how to decide and selectthe best strategy in the treatment of dental caries at a different depthto preserve the pulp tissue vitality for a longer time, and strength ofthe tooth hard tissue will maintain.

The effect of temperature on the tissue dissolution capacity of 10% calcium hypochlorite solution

BACKGROUND: The cytotoxicity of Sodium hypochlorite has always been a concern when used as an endodontic irrigant. Quest for an equally effective, but less toxic substitute has led to researches on Calcium hypochlorite (Ca(ClO)2 ) solutions. But it has been proven that 10% Calcium hypochlorite solution at room temperature (250 C) demonstrated slower rate of tissue dissolution than Sodium hypochlorite. Aim: This study was performed to assess if preheating enhanced the tissue dissolution capacity of 10% Ca(ClO)2 . MATERIALS AND METHODS: Human pulp tissue was obtained from freshly extracted single rooted mandibular premolars. The tissue weight was standardized to 9.5mg. The test groups consisted of freshly prepared Ca(ClO)2 solutions at room temperature (250 C), 450 C and 600 C. Ten specimens were assigned to each group with each specimen immersed in 2ml of the test solution. Five specimens immersed in normal saline made the control group. Every five minutes the tissue was retrieved, blotted dry, weighed and immersed back in fresh 2 ml of solution. This was continued for 60 minutes or till complete dissolution. The percentage difference in weight at each interval was calculated. The values obtained were statistically analyzed using one –way ANOVA. Intergroup comparison at different time intervals was done using Bonferroni test. RESULTS: Ca(ClO)2 solution at 600 C dissolved the tissue significantly faster than other solutions. The tissue dissolution rate of solution at 450 C was greater than that at 250 C. (P&lt; 0.05) CONCLUSION: Within the limitations of this study, it can be concluded that preheating 10% Ca(ClO)2 solution significantly enhanced its tissue dissolution capacity.

Immunohistochemical quantification of mast cells in inflamed and noninflamed pulp tissue.

Background:Dental pulp inflammation is a very complex process due to its situation in low compliance (confined environment) surrounded by mineralized dentin. Mast cells are one of the mediators of inflammation. Immunohistochemical localization of mast cells by anti-tryptase antibodies in formalin-fixed paraffin-embedded sections has been shown to be highly specific. The aim of the present study is to quantify the mast cells in inflamed and noninflamed human pulp tissue using immunohistochemical analysis.Materials and Methods:Immunohistochemical localization of mast cells by anti-tryptase antibody was done in 15 inflamed and 15 noninflamed formalin-fixed paraffin-embedded pulp tissue. A number of mast cell per five high-power fields were performed using three observers and the mean was calculated. Statistical analysis was performed using t-test.Results:The results of the present study showed an increased number of mast cells in inflamed pulp in comparison with noninflamed pulp.Conclusion:Thus, the presence of mast cells in pulp inflammation could be used as a diagnostic marker. It can also aid in the management of pulpitis as mast cell stabilizers and antihistaminic agents could be used to control pulpal pain and inflammation.

Differential Expression of Long Noncoding RNAs in Normal and Inflamed Human Dental Pulp

IntroductionDental pulp inflammation is an excellent model for the interaction between tissue inflammation and regenerative processes. It is worthwhile to better understand molecular signaling of repair and regeneration in inflammatory processes. Emerging evidence suggests that long noncoding RNA (lncRNA) participates in immune system inflammatory processes. Here we investigate the expression of lncRNAs in pulpitis, the inflammation of dental pulp tissue, and identify lncRNAs that possibly participate in inflammation responses and odontogenesis. MethodsIntegrated comparative lncRNA microarray was used to examine lncRNA and mRNA expression between inflamed and normal human pulp tissue. The differential expression of lncRNAs and mRNAs was then validated by quantitative real-time polymerase chain reaction. A bioinformatics analysis was performed to predict the function of differentially expressed lncRNAs and mRNAs. ResultsOur data indicated 752 lncRNAs were significantly differentially expressed (fold change > 2.0; P < .05) in inflamed pulp tissues compared with normal pulp tissues, including 338 upregulated and 414 downregulated lncRNAs. Among the 646 differentially expressed mRNAs (fold change > 2.0; P < .05), 460 were upregulated, and 186 were downregulated. The differentially downregulated genes are enriched for gene ontology terms related to odontogenesis and cell development in biological processes, whereas the differentially upregulated genes are related to immune and inflammation processes. ConclusionsLncRNAs are differentially expressed in inflamed human pulp tissue compared with normal pulp tissue, indicating that lncRNAs may play key roles in pulpitis pathogenesis and development.

PAR-1 and PAR-2 Expression Is Enhanced in Inflamed Odontoblast Cells

Protease-activated receptors (PARs) are G protein–coupled receptors, which are activated by proteolytical cleavage of the amino-terminus and act as sensors for extracellular proteases. We hypothesized that PAR-1 and PAR-2 can be modulated by inflammatory stimulus in human dental pulp cells. PAR-1 and PAR-2 gene expression in human pulp tissue and MDPC-23 cells were analyzed by quantitative polymerase chain reaction. Monoclonal PAR-1 and PAR-2 antibodies were used to investigate the cellular expression of these receptors using Western blot, flow cytometry, and confocal microscopy in MDPC-23 cells. Immunofluorescence assays of human intact and carious teeth were performed to assess the presence of PAR-1 and PAR-2 in the dentin-pulp complex. The results show for the first time that human odontoblasts and MDPC-23 cells constitutively express PAR-1 and PAR-2. PAR-2 activation increased significantly the messenger RNA expression of matrix metalloproteinase (MMP)–2, MMP-9, MMP-13, and MMP-14 in MDPC-23 cells (P < 0.05), while the expression of these enzymes decreased significantly in the PAR-1 agonist group (P < 0.05). The high-performance liquid chromatography and matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry analysis showed the presence of MMP-13 activity cleaving PAR-1 at specific, noncanonical site TLDPRS42↓F43LL in human dental pulp tissues. Also, we detected a presence of a trypsin-like activity cleaving PAR-2 at canonical site SKGR20↓S21LIGRL in pulp tissues. Confocal microscopy analysis of human dentin-pulp complex showed intense positive staining of PAR-1 and PAR-2 in the odontoblast processes in dentinal tubules of carious teeth compared to intact ones. The present results support the hypothesis of activation of the upregulated PAR-1 and PAR-2 by endogenous proteases abundant during the inflammatory response in dentin-pulp complex.

Exostosin 1 is expressed in human odontoblasts

ObjectiveDental pulp is soft connective tissue maintaining the vitality of the tooth, while odontoblasts form the dentin. Our earlier DNA microarray analysis revealed expression of putative tumour suppressor exostosin 1 (EXT-1) in odontoblasts. EXT-1 is essential for heparan sulphate synthesis, which may play a role in the dentin mineralization. Since the absence of the functional EXT-1 causes bone tumours, expression in odontoblasts is interesting. Our aim was to analyse further the EXT-1 expression in human tooth. DesignsDNA microarray and PCR techniques were used to study the EXT-1 expression in mature native human odontoblasts and pulp tissue as well as in newly-differentiated cultured odontoblast-like cells. Immunohistochemistry was performed to study EXT-1 protein in mature human teeth, teeth with incomplete root and developing teeth. ResultsMarkedly higher EXT-1 was observed in mature odontoblasts than in pulp at mRNA level with DNA microarray and PCR techniques. Immunohistochemistry of mature tooth revealed EXT-1 both in odontoblasts and the predentin but not in the dentin. EXT-1 was also observed in the odontoblasts of incomplete root, but the localization of the staining was different. In developing foetal tooth, staining was detected in ameloblasts and the basal lamina. ConclusionsThe detection of EXT-1 in both mature and newly-differentiated cells indicates a role in the odontoblast function, and EXT-1 staining in the predentin indicates a function in the dentin formation. Detection of EXT-1 in developing teeth indicates a role in tooth development.

DPSCs from Inflamed Pulp Modulate Macrophage Function via the TNF-α/IDO Axis

Human dental pulp stem cells (DPSCs) can be isolated from inflamed pulp derived from carious teeth with symptomatic irreversible pulpitis (I-DPSCs), which possess stemness and multidifferentiation potentials similar to DPSCs from healthy pulp. Since macrophages—essential cell players of the pulpal innate immunity—can regulate pulpal inflammation and repair, the authors investigated the immunomodulatory effects of DPSCs/I-DPSCs on macrophage functions and their underlying mechanisms. Similar to DPSCs, I-DPSCs were capable of colony-forming efficiency and adipogenic and osteo/dentinogenic differentiation under in vitro induction conditions. I-DPSCs also expressed a similar phenotypic profile of mesenchymal stem cell markers, except a relatively higher level of CD146 as compared with DPSCs. Coculture of DPSCs or I-DPSCs with differentiated THP-1 cells, the human monocyte cell line, markedly suppressed tumor necrosis factor α (TNF-α) secretion in response to stimulation with lipopolysaccharides (LPS) and/or nigericin. However, unlike TNF-α, the secreted level of interleukin 1β was not affected by coculture with DPSCs or I-DPSCs. Furthermore, DPSC/I-DPSC-mediated inhibition of TNF-α secretion by macrophages was abolished by pretreatment with 1-methyl-D-tryptophan, a specific inhibitor of indoleamine-pyrrole 2,3-dioxygenase (IDO), but not by NSC-398, a specific inhibitor of COX-2, suggesting IDO as a mediator. Interestingly, IDO expression was significantly augmented in macrophages and mesenchymal stromal cells in inflamed human pulp tissues. Collectively, these findings show that I-DPSCs, similar to DPSCs, possess stem cell properties and suppress macrophage functions via the TNF-α/IDO axis, thereby providing a physiologically relevant context for their innate immunomodulatory activity in the dental pulp and their capability for pulp repair.

Clinical and Histological Evaluation of Direct Pulp Capping on Human Pulp Tissue Using a Dentin Adhesive System.

Objective. This study presents a clinical and histological evaluation of human pulp tissue responses after direct capping using a new dentin adhesive system. Methods. Twenty-eight caries-free third molar teeth scheduled for extraction were evaluated. The pulps of 22 teeth were mechanically exposed and randomly assigned to 1 of 2 groups: Single Bond Universal or calcium hydroxide. Another group of 6 teeth acted as the intact control group. The periapical response was assayed, and a clinical examination was performed. The teeth were extracted after 6 weeks, and a histological analysis was performed. The pulp status was assessed, and the thickness of the dentin bridge was measured and categorized using a histological scoring system. Results. The clinical phase was asymptomatic for Single Bond Universal patients. Patients in the calcium hydroxide group reported mild symptoms of pain, although the histological examination revealed that dentin bridges with or without limited pulpitis had begun forming in each tooth. The universal adhesive system exhibited nonsignificantly increased histological signs of pulpitis (P > 0.05) and a significantly weaker thin mineralized tissue layer (P < 0.001) compared with the calcium hydroxide group. Conclusion. The results suggest that Single Bond Universal is inappropriate for human pulp capping; however, further long-term studies are needed to determine the biocompatibility of this agent.

Histological response of human pulps capped with calcium hydroxide and a self-etch adhesive containing an antibacterial component.

Aim:To compare human pulp tissue response following direct pulp capping with calcium hydroxide and a self-etch adhesive containing antibacterial component.Materials and Methods:Sixty-six erupted sound premolars scheduled to be extracted for orthodontic reasons were selected from 17 human subjects. Pulp exposures were made. Direct pulp capping was then performed using calcium hydroxide and a self-etch adhesive containing antibacterial component in its primer. The teeth were then restored with composite resin. Two teeth were maintained intact as a control group. After 7 and 30 days, teeth were extracted and processed for light microscopic examination using a histological scoring system. The teeth were divided into four groups (N = 16) according to the pulp capping materials used and their days of extraction. The results were then statistically analyzed by Mann-Whitney U-test.Results:After the 7-day observation period, the inflammatory reaction to the self-etch adhesive containing antibacterial component group was significantly less severe than that in the calcium hydroxide group (P < 0.05). After the 30-day observation period, the inflammatory reaction was slight in both groups, but specimens with dentin bridge formation in the self-etch adhesive group were significantly less common than those in the calcium hydroxide group (P < 0.05).

Immunohistochemical Expression of TGF-β1 and Osteonectin in engineered and Ca(OH)2-repaired human pulp tissues.

The aim of the present study was to evaluate the expression of transforming growth factor-β1 (TGF-β1) and osteonectin (ON) in pulp-like tissues developed by tissue engineering and to compare it with the expression of these proteins in pulps treated with Ca(OH)2 therapy. Tooth slices were obtained from non-carious human third molars under sterile procedures. The residual periodontal and pulp soft tissues were removed. Empty pulp spaces of the tooth slice were filled with sodium chloride particles (250-425 µm). PLLA solubilized in 5% chloroform was applied over the salt particles. The tooth slice/scaffold (TS/S) set was stored overnight and then rinsed thoroughly to wash out the salt. Scaffolds were previously sterilized with ethanol (100-70°) and washed with phosphate-buffered saline (PBS). TS/S was treated with 10% EDTA and seeded with dental pulp stem cells (DPSC). Then, TS/S was implanted into the dorsum of immunodeficient mice for 28 days. Human third molars previously treated with Ca(OH)2 for 90 days were also evaluated. Samples were prepared and submitted to histological and immunohistochemical (with anti-TGF-β1, 1:100 and anti-ON, 1:350) analyses. After 28 days, TS/S showed morphological characteristics similar to those observed in dental pulp treated with Ca(OH)2. Ca(OH)2-treated pulps showed the usual repaired pulp characteristics. In TS/S, newly formed tissues and pre-dentin was colored, which elucidated the expression of TGF-β1 and ON. Immunohistochemistry staining of Ca(OH)2-treated pulps showed the same expression patterns. The extracellular matrix displayed a fibrillar pattern under both conditions. Regenerative events in the pulp seem to follow a similar pattern of TGF-β1 and ON expression as the repair processes.

Histological evaluation of mineral trioxide aggregate and enamel matrix derivative combination in direct pulp capping: An in vivo study.

Aim:The aim of this study is to evaluate the response of human pulp tissue to mineral trioxide aggregate (MTA), Emdogain (EMD), and combination of MTA/EMD.Materials and Methods:This study was performed on sixty intact first and second premolars of human maxillary and mandibular teeth. A standard pulpal exposure was done on all the teeth and was divided into three groups of twenty teeth each and was capped with MTA, EMD, and MTA/EMD combination. The final restoration was done with resin-modified glass ionomer cement. The teeth were then extracted on the 15th or 45th day and histological evaluation done.Results:Differences in inflammatory response and thickness of dentin bridge formation of the exposed pulp to the three different groups were statistically evaluated using Chi-square and Mann–Whitney tests and were found to be significant. No significant difference was found between MTA/EMD and MTA in terms of calcified bridge formation and pulp inflammatory response to the capping materials.Conclusions:MTA and MTA/EMD combination produced a better quality hard tissue response compared with the use of EMD.

Effects of Prolyl Hydroxylase Inhibitor L-mimosine on Dental Pulp in the Presence of Advanced Glycation End Products

IntroductionProangiogenic prolyl hydroxylase (PHD) inhibitors represent a novel approach to stimulate tissue regeneration. Diabetes mellitus involves the accumulation of advanced glycation end products (AGEs). Here we evaluated the impact of AGEs on the response of human pulp tissue to the PHD inhibitor L-mimosine (L-MIM) in monolayer cultures of dental pulp–derived cells (DPCs) and tooth slice organ cultures. MethodsIn monolayer cultures, DPCs were incubated with L-MIM and AGEs. Viability was assessed based on formazan formation, live-dead staining, annexin V/propidium iodide, and trypan blue exclusion assay. Vascular endothelial growth factor (VEGF), interleukin (IL)-6, and IL-8 production was evaluated by quantitative polymerase chain reaction and immunoassays. Furthermore, expression levels of odontoblast markers were assessed, and alizarin red staining was performed. Tooth slice organ cultures were performed, and VEGF, IL-6, and IL8 levels in their supernatants were measured by immunoassays. Pulp tissue vitality and morphology were assessed by MTT assay and histology. ResultsIn monolayer cultures of DPCs, L-MIM at nontoxic concentrations increased the production of VEGF and IL-8 in the presence of AGEs. Stimulation with L-MIM decreased alkaline phosphatase levels and matrix mineralization also in the presence of AGEs, whereas no significant changes in dentin matrix protein 1 and dentin sialophosphoprotein expression were observed. In tooth slice organ cultures, L-MIM increased VEGF but not IL-6 and IL-8 production in the presence of AGEs. The pulp tissue was vital, and no signs of apoptosis or necrosis were observed. ConclusionsOverall, in the presence of AGEs, L-MIM increases the proangiogenic capacity, but decreases alkaline phosphatase expression and matrix mineralization.

Expression of DMP-1 in the human pulp tissue using low level laser therapy

This study aimed to evaluate the effects of low-level laser therapy (LLLT) on DMP-1 expression in pulp tissue repair of human primary teeth. Twenty mandibular primary molars were randomly assigned into the following groups: Group I—Buckley’s Formocresol (FC); Group II—Calcium Hydroxide (CH); Group III—LLLT + CH and Group IV—LLLT + Zinc oxide/Eugenol. The teeth at the regular exfoliation period were extracted for histological analysis and immunolocalization of DMP-1. Descriptive analysis was performed on the dentin pulp complex. Histopathological assessment showed internal resorption in group FC. Groups CH and LLLT + CH provided better pulpal repair due to the absence of inflammation and the formation of hard tissue barrier. These two groups presented odontoblastic layer expressing DMP-1. According to this study, low level laser therapy preceding the use of calcium hydroxide exhibited satisfactory bio-inductive activity on pulp tissue repair of human primary teeth. However, other histological and cellular studies are needed to confirm the laser tissue action and efficacy.