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During pulp inflammation, recruited macrophages can differentiate into 2 phenotypes: proinflammatory M1 and anti-inflammatory M2. Pulp fibroblasts have previously been shown to regulate pulp inflammation via cytokine and growth factor secretion. We hypothesized that upon carious injury, pulp fibroblasts interact with macrophages and modulate their differentiation. Cultures of pulp fibroblasts were physically injured and incubated with lipoteichoic acid (LTA) to mimic the pulp environment underlying a carious lesion. Physical injuries without LTA were performed on cultured fibroblasts to simulate the surrounding pulp tissue. Fibroblast supernatants were collected and added to undifferentiated macrophages to study their differentiation into M1 or M2 phenotypes by investigating cytokine secretion profiles and phagocytosis capacity. Histologic staining and immunofluorescence were performed on healthy and carious human tooth sections to localize the 2 macrophage phenotypes. LTA-stimulated fibroblasts induced macrophage differentiation into the M1 phenotype with a significant increase both in tumor necrosis factor alpha secretion and phagocytosis capacity. By contrast, injured fibroblasts without LTA led to M2 differentiation with a significant increase in interleukin 10 secretion and low phagocytosis capacity. In carious teeth, M1 macrophages were detected mainly in the pulp zone underlying caries, whereas M2 macrophages were detected in the peripheral inflammatory zone. Fibroblasts induced macrophage differentiation to proinflammatory M1 with high bacteria phagocytosis capacity to control infection at the carious front. Fibroblasts located at the periphery of the inflammatory zone induced macrophage differentiation to anti-inflammatory M2. The fine balance between the 2 phenotypes may represent a prerequisite for initiating the healing process. [ABSTRACT FROM AUTHOR]

Upon traumatic injuries or carious lesions, the elimination of bacteria infiltrating the pulp is recognized as a prerequisite for initiating the regeneration process. Complement is a major system involved in initiating the inflammatory reaction and the subsequent bacteria elimination. This plasma system of above 35 proteins is synthesized by the liver and some immune cells. It is activated by 3 pathways: the classical, alternative, and lectin pathways that can be triggered by physical injuries, infection, and biomaterials. Recent data have shown that the pulp fibroblast represents a unique nonimmune cell type able to synthesize Complement proteins. Indeed, after physical injuries/bacteria stimulation, the pulp fibroblast has been shown to synthesize and to activate the complement system leading to the production of biologically active molecules such as C5a, C3b, and the membrane attack complex. This local secretion represents a rapid and efficient mechanism for eliminating bacteria invading the pulp, thus supporting complement activation from the plasma. Pulp fibroblast-secreted Complement proteins allow cariogenic bacteria direct lysis via membrane attack complex formation on their surface, phagocytic cell recruitment by producing C5a and cariogenic bacteria opsonization by C3b fixation on their surface, stimulating cariogenic bacteria phagocytosis. Overall, this review highlights that, in addition to initiating the inflammatory reaction, pulp fibroblasts also provide a powerful control of this inflammation via local Complement activation. The pathogen elimination capacity by fibroblast-produced complement demonstrates that this system is a strong local actor in arresting bacterial progression into the dental pulp. [ABSTRACT FROM AUTHOR]

Vital pulp therapy (VPT) in mature permanent teeth with carious pulp exposure has been a matter of debate, with root canal therapy being the conventional standard of care. Previously reported negative outcomes for VPT in these teeth were based on data from studies that have used calcium hydroxide in direct pulp capping and partial and full pulpotomy. The introduction of hydraulic calcium silicate-based materials with sealing and bioactive potentials have opened a new era in VPT with more favorable results. Understanding the histopathology and histobacteriology of the cariously exposed pulp and the healing potential of the inflamed pulp could guide the decision-making process toward an ultraconservative management of these teeth. However, proper case selection, strict aseptic condition, capping material, and good coronal seal are crucial for long-term success. [ABSTRACT FROM AUTHOR]

The balance between periapical tissue inflammation and regeneration after the removal of necrotic/infected tissues is pivotal in determining the success of endodontic treatment. This study was designed to investigate the effect of silicate-based root canal sealer BioRoot RCS (BRCS; Septodont, Saint-Maur-des-Fossés, France) on modulating the inflammatory mechanisms and early steps of regeneration initiated by human periodontal ligament (PDL) fibroblasts. Samples of BRCS and Pulp Canal Sealer (PCS; SybronEndo, Orange, CA) were incubated in culture medium to obtain material extracts. To simulate bacterial infection and endodontic sealer use, PDL fibroblasts were stimulated with lipopolysaccharides and cultured with material extracts. The secretion of proinflammatory cytokine (interleukin 6) and growth factor (transforming growth factor beta 1) were quantified by enzyme-linked immunosorbent assay. Inflammatory cell recruitment sequence was investigated using a human inflammatory monocytic cell line (THP-1) that can be activated into macrophage-like cells. The adhesion of THP-1 to endothelial cells (human umbilical vein endothelial cells) was studied using fluorescent THP-1, their migration using Boyden chambers, and their activation into macrophage-like cells using a cell adhesion assay. The proliferation of PDL fibroblasts was quantified by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, whereas the migration of PDL stem cells was investigated using Boyden chambers after immunofluorescence and reverse transcription polymerase chain reaction characterization. Interleukin 6 secretion decreased with BRCS, whereas it increased with PCS. Transforming growth factor beta 1 secretion significantly increased only with BRCS. The material extracts did not affect THP-1 adhesion to human umbilical vein endothelial cells, but only BRCS inhibited their migration. Moreover, activation of THP-1 decreased with BRCS and to a lesser extent with PCS. Finally, BRCS increased PDL fibroblast proliferation without affecting PDL stem cell migration. By contrast, PCS decreased PDL fibroblast proliferation and PDL stem cell migration. This work shows that the endodontic sealers modulate the PDL inflammatory and regeneration potentials in vitro. It demonstrates that BRCS has anti-inflammatory effects and the potential to promote tissue regeneration. • The initial steps of inflammation and regeneration can be investigated in vitro. • BioRoot decreases the sequence of inflammatory THP-1 cell recruitment. • BioRoot induces TGF-β1 secretion by PDL fibroblasts and their proliferation. • BioRoot has an anti-inflammatory and periodontal tissue regeneration potentials. [ABSTRACT FROM AUTHOR]

Previous 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. The 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. Pulp 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. These 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. • Pulp fibroblasts constitutively express and secrete the complement C3b fragment. • The released C3b fragment is fixed on bacteria and recognized by its CR1 receptor on the macrophages. • This opsonization is followed by a stimulation of bacteria phagocytosis. • Pulp fibroblasts mediate the process of phagocytosis and play a significant role in the dental pulp local regulation of inflammation. [ABSTRACT FROM AUTHOR]

Abstract Introduction A lack of information exists regarding the efficacy of RetroMTA (BioMTA, Seoul, Korea) directly applied on the pulp in vital pulp therapy. This study was designed to examine the clinical efficacy of RetroMTA compared with ProRoot mineral trioxide aggregate (MTA) (Dentsply Tulsa Dental, Tulsa, OK) for partial pulpotomy. Methods Partial pulpotomy was performed in 22 healthy human maxillary and mandibular third molars planned for extraction. The teeth were randomly divided into 2 groups (n = 11) and underwent partial pulpotomy with RetroMTA and ProRoot MTA as the control. The teeth were then restored with glass ionomer cement. Clinical and electric pulp tests were performed after 1 and 8 weeks. The teeth were radiographed and extracted at 8 weeks. Histologic sections were prepared and analyzed for pulp inflammation and dentinal bridge formation. Data were analyzed using the Mann-Whitney U test. Results Clinical examination after 1 and 8 weeks showed no sensitivity to heat, cold, or palpation in the ProRoot MTA and RetroMTA groups. Periapical radiographs taken before the extraction of teeth showed no evidence of periapical pathology. Electric pulp testing revealed no sensitivity. Data comparisons using the Mann-Whitney U test showed no significant difference between the materials with regard to the pulp inflammation type, intensity and extension (P =.3), or bridge continuity (P =.12). However, these data revealed a significant difference between the 2 materials in pulp morphology (P <.05) and bridge thickness (P <.01). Conclusions This is the first work to evaluate a RetroMTA histologic outcome in partial pulpotomy in human permanent teeth. It shows pulp disorganization, an absence of inflammation, and discontinuous mineralization, which may represent a potential drawback with RetroMTA in this indication. Highlights • The dental pulp response to RetroMTA was investigated after partial pulpotomy of permanent human teeth. • There was no significant statistical difference between materials based on the pulp inflammation type, intensity and extension, or bridge continuity. • Pulp disorganization and thin dentin bridge formation are considerable disadvantages for RetroMTA. [ABSTRACT FROM AUTHOR]

Abstract Introduction On stimulation by lipoteichoic acid or by a physical injury, fibroblasts have been shown to play a major role in the initiation of the pulp inflammatory reaction and healing through secretion of complement proteins and growth factors. The application of direct pulp-capping materials on these cells may interfere with the inflammatory and the healing processes within the pulp's inextensible environment. This work was designed to study in vitro the effects of silicate-based materials on pulp fibroblast modulation of the initial steps of pulp inflammation and healing. Methods The effects of Biodentine, TheraCal, and Xeno III eluates were studied on lipoteichoic acid–stimulated and physically injured fibroblasts. Cytokine secretion (interleukin 6, vascular endothelial growth factor, fibroblast growth factor-2, and transforming growth factor-β1) was quantified by enzyme-linked immunosorbent assay. Inflammatory THP-1 adhesion to endothelial cells and their migration and activation were studied in vitro. Human pulp fibroblast proliferation was investigated with the MTT test, and their migration to the injury site was studied with the scratch healing assay. Results Interleukin 6 and vascular endothelial growth factor secretion increased with all materials but to a lesser extent with Biodentine. Fibroblast growth factor-2 and transforming growth factor-β1 secretion was significantly higher with Biodentine than with all other materials. THP-1 cell adhesion to endothelial cells and their activation were reduced by Biodentine and TheraCal. However, their migration decreased only with Biodentine. Fibroblast proliferation significantly increased with Biodentine but significantly decreased with Xeno III after day 6. Finally, only Biodentine induced fibroblast migration to the injury site in the scratch assay. Conclusions These results confirm that pulp-capping materials affect the early steps of pulp inflammation and healing. They show that Biodentine had the highest pulp healing and anti-inflammatory potential when compared with the resin-containing materials. This highlights the interest of the material choice for direct pulp-capping. Highlights • Direct pulp-capping materials modulate the initial steps of pulp inflammation and healing. • Biodentine inhibits pulp inflammation and induces pulp healing. • Adding resins to silicates alters their bioactivity. • Direct pulp-capping material choice is crucial for the clinical outcome. [ABSTRACT FROM AUTHOR]

Introduction We recently reported that caries-associated C5a receptor (C5aR) expression and activation result in up-regulation of brain-derived neurotropic factor secretion by pulp fibroblasts inducing prominent neurite outgrowth toward the carious site. Our data further showed a negative regulation of this brain-derived neurotropic factor secretion by C5L2, another C5aR. C5L2 was considered a nonfunctional receptor and thus has received much less attention than C5aR. The aim of this study was to identify the role of C5L2 in pulp fibroblast–mediated neurite outgrowth. Methods In this study, lipoteichoic acid (LTA) was used to mimic dental caries–like inflammation. To evaluate the role of C5L2 in pulp neurite outgrowth, human pulp fibroblasts were C5L2 small interfering RNA silenced and cocultured with human neurons in a nerve growth assay system. Results C5L2 silencing drastically increased the neurite outgrowth toward the LTA-stimulated pulp fibroblasts. The number of neurites detected was increased in the LTA-treated pulp fibroblasts. Conclusions Our results show that C5L2 constitutes a negative regulator of the neurite outgrowth under LTA stimulation. Of the events occurring during dentin-pulp regeneration, nerve regeneration is the key factor for maintaining tooth viability after infection or injury. Our study provides a foundation for creating therapeutic tools that target pulp fibroblasts during pulp/nerve regeneration. [ABSTRACT FROM AUTHOR]

Introduction Numerous studies reported dentin bridge formation after pulp capping with tricalcium silicates. By contrast, pulp capping with resins leads to pulp toxicity and inflammation. Hybrid materials made up of tricalcium silicates and resins have also been developed to be used in direct pulp capping. This work was designed to study the consequences of adding resins to tricalcium silicates by investigating TheraCal (BISCO, Lançon De Provence, France) and Biodentine (Septodont, Saint Maur des Fosses, France) interactions with the dental pulp. Methods Media conditioned with the biomaterials were used to analyze pulp fibroblast proliferation using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) test and proinflammatory cytokine interleukin 8 (IL-8) secretion using the enzyme-linked immunosorbent assay. The effects of conditioned media on dentin sialoprotein (DSP) and nestin expression by dental pulp stem cells (DPSCs) were investigated by immunofluorescence. The materials' interactions with the vital pulp were investigated using the entire tooth culture model. Results TheraCal-conditioned media significantly decreased pulp fibroblast proliferation, whereas no effect was observed with Biodentine. When DPSCs were cultured with Biodentine-conditioned media, immunofluorescence showed an increased expression of DSP and nestin. This expression was lower with TheraCal, which significantly induced proinflammatory IL-8 release both in cultured fibroblasts and entire tooth cultures. This IL-8 secretion increase was not observed with Biodentine. Entire tooth culture histology showed a higher mineralization with Biodentine, whereas significant tissue disorganization was observed with TheraCal. Conclusions Within the limits of these preclinical results, resin-containing TheraCal cannot be recommended for direct pulp capping. [ABSTRACT FROM AUTHOR]

Introduction Questions exist regarding the efficacy of resin-containing materials such as TheraCal directly applied on the pulp. This study sought to investigate the clinical efficacy of TheraCal as compared with Biodentine and ProRoot mineral trioxide aggregate (MTA) for partial pulpotomy. Methods In this clinical trial, partial pulpotomy was performed for 27 sound human maxillary and mandibular third molars scheduled for extraction. The teeth were randomly divided into 3 groups ( n = 9) and underwent partial pulpotomy with TheraCal, Biodentine, and ProRoot MTA. The teeth were then restored with glass ionomer cement. Clinical and electric pulp tests were performed after 1 and 8 weeks. The teeth were radiographed and extracted at 8 weeks. Histologic sections were prepared and analyzed for pulp inflammation and dentinal bridge formation. Data were analyzed by using one-way analysis of variance. Results Clinical examination showed no sensitivity to heat, cold, or palpation in ProRoot MTA and Biodentine groups. Two patients in TheraCal group (20%) reported significant pain at 1 week. Periapical radiographs showed no periapical pathology, and electric pulp test revealed a normal pulp response with no hypersensitivity. Inflammation was absent with all materials at 8 weeks. Normal pulp organization was seen in 33.33% of the teeth in ProRoot MTA, 11.11% in TheraCal, and 66.67% in Biodentine group ( P = .06). Biodentine group showed complete dentinal bridge formation in all teeth, whereas this rate was 11% and 56% in TheraCal and ProRoot MTA groups, respectively ( P = .001). Conclusions Overall, Biodentine and MTA performed better than TheraCal when used as partial pulpotomy agent and presented the best clinical outcomes. [ABSTRACT FROM AUTHOR]

Introduction The role of complement, especially through the C5a fragment, is well-known for the initiation of inflammation. Its involvement in regeneration has been shown more recently by the recruitment of mesenchymal stem cells. C5a can be produced locally by the pulp fibroblasts in response to injury or infection. This work aims to investigate the effect of different pulp capping biomaterials on complement activation and its possible influence on inflammatory and pulp stem cell recruitment. Methods Conditioned media were prepared from 3 pulp capping biomaterials: Biodentine (Septodont, Saint-Maur-des-Fosses, France), TheraCal (BISCO, Lançon De Provence, France), and Xeno III (Dentsply Sirona, Versaille, France). Injured pulp fibroblasts were cultured with these conditioned media to analyze C5a secretion using an enzyme-linked immunosorbent assay. Dental pulp stem cells (DPSCs) were isolated from human third molar explants by magnetic cell sorting with STRO-1 antibodies. The expression of C5a receptor on DPSCs and inflammatory (THP-1) cells was investigated by immunofluorescence. The migration of both DPSCs and THP-1 cells was studied in Boyden chambers. Results Pulp fibroblast production of C5a significantly increased when the cells were incubated with TheraCal- and Xeno III–conditioned media. The recruitment of cells involved in inflammation (THP-1 cells) was significantly reduced by Biodentine- and TheraCal-conditioned media, whereas the migration of DPSCs was reduced with TheraCal- and Xeno III–conditioned media but not with that of Biodentine. The involvement of C5a in cell recruitment is demonstrated with a C5a receptor–specific antagonist (W54011). Conclusions After pulp injury, the pulp capping material affects complement activation and the balance between inflammation and regeneration through a differential recruitment of DPSCs or inflammatory cells. [ABSTRACT FROM AUTHOR]

Introduction Complement activation is considered a major mechanism in innate immunity. Although it is mainly involved in initiating inflammation, recent data reported its involvement in other processes such as tissue regeneration. In the dental pulp, complement C5a fragment has been shown to be involved in the recruitment of dental pulp stem cells (DPSCs). This study sought to investigate the possible role of C3a, another complement fragment, in the early steps of dentin-pulp regeneration. Methods Expression of C3a receptor (C3aR) was investigated by immunofluorescence and reverse transcriptase polymerase chain reaction on cultured pulp fibroblasts, STRO-1–sorted DPSCs, as well as on human tooth sections in vivo . The effect of C3a on proliferation of both DPSCs and pulp fibroblasts was investigated by MTT assay. Cell migration under a C3a gradient was investigated by using microfluidic chemotaxis chambers. Results C3aR was expressed in vivo as well as in cultured pulp fibroblasts co-expressing fibroblast surface protein and in DPSCs co-expressing STRO-1. Addition of recombinant C3a induced a significant proliferation of both cell types. When subjected to a C3a gradient, DPSCs were mobilized but not specifically recruited, whereas pulp fibroblasts were specifically recruited following a C3a gradient. Conclusions These results provide the first demonstration of C3aR expression in the dental pulp and demonstrate that C3a is involved in increasing DPSCs and fibroblast proliferation, in mobilizing DPSCs, and in specifically guiding fibroblast recruitment. This provides an additional link to the tight correlation between inflammation and tissue regeneration. [ABSTRACT FROM AUTHOR]

Introduction The transient receptor potential (TRP) ion channels have emerged as important cellular sensors in both neuronal and non-neuronal cells, with TRPA1 playing a central role in nociception and neurogenic inflammation. The functionality of TRP channels has been shown to be modulated by inflammatory cytokines. The aim of this study was to investigate the effect of inflammation on odontoblast TRPA1 expression and to determine the effect of Biodentine (Septodent, Paris, France) on inflammatory-induced TRPA1 expression. Methods Immunohistochemistry was used to study TRPA1 expression in pulp tissue from healthy and carious human teeth. Pulp cells were differentiated to odontoblastlike cells in the presence of 2 mmol/L beta-glycerophosphate, and these cells were used in quantitative polymerase chain reaction, Western blotting, calcium imaging, and patch clamp studies. Results Immunofluorescent staining revealed TRPA1 expression in odontoblast cell bodies and odontoblast processes, which was more intense in carious versus healthy teeth. TRPA1 gene expression was induced in cultured odontoblastlike cells by tumor necrosis factor alpha, and this expression was significantly reduced in the presence of Biodentine. The functionality of the TRPA1 channel was shown by calcium microfluorimetry and patch clamp recording, and our results showed a significant reduction in tumor necrosis factor alpha–induced TRPA1 responses after Biodentine treatment. Conclusions In conclusion, this study showed TRPA1 to be modulated by caries-induced inflammation and that Biodentine reduced TRPA1 expression and functional responses. [ABSTRACT FROM AUTHOR]

Introduction Tricalcium silicate–based materials are recognized as bioactive materials through their capacity to induce hard tissue formation both in the dental pulp and bone. Sealing the apex implies that the root canal filling materials interact with the periapical tissues. This work was designed to study the interactions of newly developed tricalcium silicate cement (BioRoot RCS; Septodont, Saint Maur Des Fosses, France) with apical tissue compared with a standard zinc oxide–eugenol sealer (Pulp Canal Sealer [PCS]; SybronEndo, Orange, CA). Methods Cell viability was assessed by direct contact between human periodontal ligament (PDL) cells and BioRoot RCS or PCS. In addition, an in vitro tooth model was used to study the interactions between these materials and PDL cells. For this purpose, human extracted incisors were sectioned at the enamel-cementum junction; root canals were prepared, sterilized, and filled with lateral condensation with both materials. The root apices were dipped in the culture medium for 24 hours. These conditioned media were used to investigate their effects on human PDL cells. Cell proliferation was investigated with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and the secretion of angiogenic and osteogenic growth factors was quantified using an enzyme-linked immunosorbent assay. Results BioRoot RCS has less toxic effects on PDL cells than PCS and induced a higher secretion of angiogenic and osteogenic growth factors than PCS. Conclusions Taken together, these preclinical results suggest that the calcium silicate cement (BioRoot RCS) has a higher bioactivity than the zinc oxide–eugenol sealer (PCS) on human PDL cells. [ABSTRACT FROM AUTHOR]

Introduction The calcium-releasing ability of pulp-capping materials induces pulp tissue regeneration. Tricalcium silicate–based materials produce calcium hydroxide as a by-product of hydration. Assessment of hydration and calcium ion leaching is usually performed on samples that have been aged in physiological solution for a predetermined period of time. The hydration and activity of the materials in vivo may not be similar to those displayed in vitro because of insufficient fluid available in contact with dentin. The aim of this research was the assessment of hydration of Biodentine, Theracal LC, and a prototype radiopacified tricalcium silicate–based material after pulp capping and to compare it with direct hydration in an aqueous solution. Methods The extent of hydration of Biodentine, Theracal LC, and a prototype radiopacified tricalcium silicate–based material with a similar composition to Biodentine but not incorporating the additives was assessed by scanning electron microscopy and energy dispersive spectroscopy of polished specimens after being allowed to hydrate in Hank's balanced salt solution for 14 days. The extent of hydration was compared with material hydration when used as direct pulp capping materials by using a tooth culture model. Material activity was also assessed by x-ray diffraction analysis to investigate the deposition of calcium hydroxide by the materials, and calcium ion leaching in Hank's balanced salt solution was assessed by ion chromatography. Results Biodentine and the prototype tricalcium silicate cement hydrated and reaction by-products were deposited in the cement matrix both after pulp capping and when incubated in an aqueous solution. Calcium hydroxide was formed, and calcium ions were leached in solution. Theracal LC hydration was incomplete because of the limited moisture diffusion within the material. Thus, no calcium hydroxide was produced, and a lower calcium ion leaching was recorded. Conclusions Theracal LC had a heterogeneous structure with large unhydrated particles because not enough moisture was present to allow hydration to proceed. Biodentine composition was shown to be optimized, and the environmental conditions did not affect material microstructure. Biodentine exhibited formation of calcium hydroxide and calcium ion leaching, which are beneficial to the dental pulp. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Little information is yet available on the signals involved in progenitor cell migration that precede reparative dentin synthesis. Our aim was to investigate the effect of the controlled release of fibroblast growth factor (FGF)-2 and transforming growth factor β1 (TGF-β1) on permanent teeth pulp cell proliferation and progenitor cell migration. Methods: FGF-2 and TGF-β1 were encapsulated into a biodegradable polymer matrix of lactide and glycolide. Human pulp cells were prepared from third molars, and progenitor cells were sorted by STRO-1. The synthesized microsphere toxicity was checked with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test. The growth factor release kinetics were checked by an enzyme-linked immunosorbent assay while maintaining their biological activity and were evaluated by investigating their effects on pulp cell proliferation. Their chemotactic potential was investigated on STRO-1–sorted cells in a migration chamber on Matrigel (Cambrex Bio Science, Walkersville, MD). Results: The cell viability was unaffected by the presence of microspheres. The released amount of FGF-2 and TGF-β1 from the microspheres was maintained after 21 days. Increasing the FGF-2–loaded microsphere concentration or the release period significantly increased dental pulp cell proliferation. TGF-β1 acted as a potent chemotactic factor of STRO-1–sorted cells. Conclusions: Encapsulating TGF-β1 and FGF-2 in a biodegradable polymer of lactide and glycolide microsphere allowed a sustained release of growth factors and provided a protection to their biological activities. Our results clearly show the usefulness of growth factor controlled release in investigating the early events of pulp/dentin regeneration. It provides additional data on the signals required for vital pulp therapy and future tissue engineering. [Copyright &y& Elsevier]

Abstract: Introduction: The purposes of the present study were to (1) assess the effect of the addition of benzalkonium chloride to sodium hypochlorite on its wetting properties, contact angle, and surface energy; (2) determine the critical micellar concentration of benzalkonium chloride in sodium hypochlorite; and (3) investigate the influence of addition of benzalkonium chloride on the free chlorine level, cytotoxicity, and antiseptic properties of the mixture. Methods: Solutions of benzalkonium chloride, with concentrations ranging from 0%–1%, were mixed in 2.4% sodium hypochlorite and tested as follows. The wetting properties were investigated by measuring the contact angle of the solutions on a nondehydrated dentin surface by using the static sessile drop method. The pending drop technique was subsequently used to determine the surface energy of the solutions. The critical micellar concentration of benzalkonium chloride mixed in sodium hypochlorite was calculated from the data. When 2.4% NaOCl was mixed with benzalkonium chloride at the critical micellar concentration, 3 parameters were tested: free chloride content, cytotoxicity, and antibacterial effects against Enterococcus faecalis. Results: The contact angle (P < .001) as well as the surface energy (P < .001) significantly decreased with increasing benzalkonium chloride concentrations. The critical micellar concentration of benzalkonium chloride in sodium hypochlorite was 0.008%. At this concentration, the addition of benzalkonium chloride had no effect on the free chlorine content, cytotoxicity, or antibacterial efficiency of the mixture. Conclusions: The addition of benzalkonium chloride to sodium hypochlorite at the critical micellar concentration reduced the contact angle by 51.2% and the surface energy by 53.4%, without affecting the free chloride content, cytotoxicity, or antibacterial properties of the mixture. [Copyright &y& Elsevier]

Abstract: Introduction: Transient receptor potential (TRP) channels comprise a group of nonselective calcium-permeable cationic channels, which are polymodal sensors of environmental stimuli such as thermal changes and chemicals. TRPM8 and TRPA1 are cold-sensing TRP channels activated by moderate cooling and noxious cold temperatures, respectively. Both receptors have been identified in trigeminal ganglion neurones, and their expression in nonneuronal cells is now the focus of much interest. The aim of this study was to investigate the molecular and functional expression of TRPA1 and TRPM8 in dental pulp fibroblasts. Methods: Human dental pulp fibroblasts were derived from healthy molar teeth. Gene and protein expression was determined by polymerase chain reaction and Western blotting. Cellular localization was investigated by immunohistochemistry, and TRP functionality was determined by Ca2+ microfluorimetry. Results: Polymerase chain reaction and Western blotting showed gene and protein expression of both TRPA1 and TRPM8 in fibroblast cells in culture. Immunohistochemistry studies showed that TRPA1 and TRPM8 immunoreactivity co-localized with the human fibroblast surface protein. In Ca2+ microfluorimetry studies designed to determine the functionality of TRPA1 and TRPM8 in pulp fibroblasts, we showed increased intracellular calcium ([Ca2+]i) in response to the TRPM8 agonist menthol, the TRPA1 agonist cinnamaldehyde, and to cool and noxious cold stimuli, respectively. The responses to agonists and thermal stimuli were blocked in the presence of specific TRPA1 and TRPM8 antagonists. Conclusions: Human dental pulp fibroblasts express TRPA1 and TRPM8 at the molecular, protein, and functional levels, indicating a possible role for fibroblasts in mediating cold responses in human teeth. [Copyright &y& Elsevier]

Abstract: Introduction: Map-1B belongs to the family of proteins that govern the dynamic state and organization of microtubules within cells. MAP-1B is a microtubule-associated protein highly expressed during the development of the nervous system. Its expression, regulated by the fragile X mental retardation protein (FMRP), is essential to stabilize microtubules during the elongation of dendrites and neurites. Other microtubules-associated molecules such as tau or MAP2 seem to act similarly. The aim of this work was to identify the MAP-1B expression in in vitro and in vivo human odontoblasts during development and carious processes. The expression of MAP2 and tau was also studied. Materials and Methods: In cultured cells, MAP-1B expression was analyzed by real-time polymerase chain reaction, flow cytometry, and Western blot. Its distribution was visualized by in situ hybridization and immunochemistry both in vitro and in vivo. The expression of FMRP, MAP2, and tau was identified by real-time polymerase chain reaction and immunochemistry. Results: MAP-1B is specifically expressed in odontoblasts from adult third molars as well as incisor germs from human embryos. In adult carious teeth, it is also expressed in newly differentiated dentin-forming cells. In vitro, MAP-1B expression is related to the differentiation state of odontoblasts. MAP-1B clearly underlines the cellular architecture of cell bodies and processes of differentiated cells. FMRP, MAP2, and tau are also detected in vivo. Conclusion: On the basis of these data, MAP-1B could be considered as a new protein involved in the terminal differentiation of odontoblasts. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to record the time-course diffusion of hydrogen peroxide through human dentin from a peroxide carbamide gel designed for the walking bleach technique in order to determine its optimal renewal time. It was considered that the optimal renewal rate corresponded to the time necessary to achieve 80% of the maximal diffusion because a much longer time does not involve further significant diffusion. Thirty-six freshly extracted human premolars were used for this study. Eighteen were extracted for orthodontic reasons on patients under 20 years old (young-teeth group). Eighteen were extracted for periodontal reasons on patients between 40 and 60 years old (old-teeth group). The teeth were endodontically treated, and a flat defect was created at the enamel-cementum junction. The teeth were suspended in vials containing water, and the access cavities were filled with 20 μL of 20% hydrogen peroxide gel. The amount of diffusing hydrogen peroxide was assessed at 1 hour, 24 hours, 48 hours, and 120 hours. The diffusive flux and the maximal diffusion were calculated as well as the optimal renewal time. Hydrogen peroxide diffusion through young teeth lasted 352 hours but lasted 291 hours through old teeth. Diffusive flux and maximal diffusion were higher through young teeth than through old teeth. The optimal renewal time for young teeth was 33 hours and for old teeth was 18 hours. [Copyright &y& Elsevier]

Objectives: Odontoblasts are highly differentiated post-mitotic cells, which under pathological conditions such as carious lesions and dental injuries may degenerate and be replaced by other pulp cells. We have recently shown that this physiological event can be reproduced in an in vitro assay system, but is highly modified by the presence of unpolymerized resinous monomers. Our hypothesis was that the photopolymerization of the monomers in the bonding agents might abolish these negative effects. The purpose of this study was to evaluate the effects of polymerized dentin bonding agents, through dentin slices, on odontoblast differentiation in vitro.Methods: Pulp cells were obtained from human third molars. They were used to study the effects of four dentin bonding agents through 0.7 mm dentin slices which served as a barrier between the bonding agents and the culture medium. The media containing the bonding agents'' extracts were added at non-toxic concentrations onto the cultured cells. Immunohistochemistry was performed to study the differentiation of pulp fibroblasts into odontoblasts under these conditions by evaluating the expression of several odontoblast specific genes.Results: Pulp fibroblasts cultivated under these conditions synthesized type I collagen, osteonectin, dentin sialoprotein and nestin at the same level as in control cultures. Moreover, pulp cells synthesized a mineralized nodular extracellular matrix. Expression of these proteins was higher in the cells contributing to the nodule formation. In addition, except nestin, all these proteins were expressed in the mineral nodules.Significance: This work shows the lack of effects of photopolymerized bonding agents, through dentin slices, on cytodifferentiation of secondary odontoblasts. [Copyright &y& Elsevier]

The purpose of this study was to compare ISO standards versus a new technique for in vitro evaluation of cytotoxicity of root canal sealers. The cytotoxicity of AH Plus, Cortisomol, and Sealapex was first recorded according to ISO standards on L 929 fibroblasts by the MTT assay. In parallel, 30 single-rooted teeth were cut at the cementum enamel junction (CEJ), and the roots were prepared and sterilized before filling with the lateral condensation using one of three sealers (n = 10). The apexes of the roots were dipped into 1 ml of minimum essential medium for 1, 2, and 30 days renewing the medium every other day. After 24-h contact between the medium and the filled roots, the medium was used to measure the cytotoxicity on L 929 with the MTT assay. ISO standards always gave a statistically higher cytotoxicity than the root-dipping technique (p < 0.0001), whatever the sealer and the exposure time. The ISO standards showed statistically significant differences among the sealers (p < 0.0001). AH Plus was noncytotoxic, Cortisomol showed a high cytotoxicity decreasing over time (p < 0.001), and Sealapex displayed a high cytotoxicity that did not decrease over time (NS). The new technique showed statistically significant differences among the sealers (p = 0.001), but the differences were so small that they were likely not clinically relevant. The high cytotoxicity of Sealapex decreased over time but the cytotoxicity of AH Plus and Cortisomol did not. The results show that the ISO standards may strongly over-evaluate the cytotoxicity of the endodontic sealers, emphasize the difference among the sealers, and may clinically correspond to a large overfilling. The new technique reduces the discrimination of the test and may clinically correspond to a classical filling. Therefore, both methods might be considered as clinically relevant, corresponding to classical and overfilling conditions. [Copyright &y& Elsevier]

The purpose of this study was to evaluate the sealing properties of four root canal sealers. Forty-eight maxillary central incisors were instrumented with Profile rotary instruments. They were randomly divided into four groups (n = 12) and filled using lateral condensation with one of the four sealers: Sealapex, Pulp Canal Sealer, AH 26, and Ketac-Endo. The apical leakage was measured with a fluid filtration method and expressed as L s−1 KPa−1. The teeth filled with Sealapex displayed a higher apical leakage (8.42 ± 4.2 10−11 L s−1 KPa−1) than those filled with AH 26 (2.10 ± 1.39 10−11 L s−1 KPa−1), Pulp Canal Sealer (0.17 ± 0.09 10−11 L s−1 KPa−1) or Ketac-Endo (0.32 ± 0.24 10−11 L s−1 KPa−1) (p < 0.01). No statistically significant difference was found among AH 26, Pulp Canal Sealer, and Ketac-Endo. No correlation was found between the sealing efficiency of the four sealers and their adhesive properties recorded in a previous study. [Copyright &y& Elsevier]

Fibroblasts represent the most abundant population within the dental pulp. Although other cell types such as odontoblasts and stem cells have been extensively investigated, very little attention was given to the fibroblasts, which have major roles in regulating the pulp biology and function under normal and pathologic conditions. Indeed, although pulp fibroblasts control the pulp vascularization and innervation under physiological conditions, these cells synthesize growth factors that enhance dentin-pulp regeneration, vascularization, and innervation. Pulp fibroblasts also represent a unique cell population because they are the only non-hepatic and non-immune cell type capable of synthesizing all complement proteins leading to production of biologically active fragments such as C3a, C5a, and membrane attack complex, which play major roles in the pulp regeneration processes. C3a fragment is involved in inducing the proliferation of both stem cells and pulp fibroblasts. It is also involved in stem cell mobilization and pulp fibroblast recruitment. C5a guides nerve sprouting and stem cell recruitment. The membrane attack complex fixes on cariogenic bacteria walls, leading to their direct destruction. These data demonstrate the central role played by pulp fibroblasts in regulating the dentin-pulp tissue by directly destroying cariogenic bacteria and by releasing bioactive fragments involved in nerve sprouting and stem cell recruitment and pulp regeneration. Taken together, this shows that targeting pulp fibroblasts represents a realistic strategy to induce complete dentin-pulp regeneration. [ABSTRACT FROM AUTHOR]

Many aspects of dentin pulp tissue regeneration have been investigated, and it has been shown that dentin pulp has a high regeneration capacity. This seems to be because of the presence of progenitor cells and inductive regeneration signals from different origins. These signals can be liberated after the acidic dissolution of carious dentin as well as from pulp fibroblasts and endothelial cells in cases of traumatic injury. Thus, both carious lesions and pulp cells provide the required mediators for complete dentin-pulp regeneration including reparative dentin secretion, angiogenesis, and innervation. Additionally, all dentin pulp insults including carious “infection,” traumatic injuries, application of restorative materials on the injured dentin pulp, and subsequent apoptosis are known activators of the complement system. This activation leads to the production of several biologically active fragments responsible for the vascular modifications and the attraction of immune cells to the inflammatory/injury site. Among these, C5a is involved in the recruitment of pulp progenitor cells, which express the C5a receptor. Thus, in addition to dentin and pulp cells, plasma should be considered as an additional source of regeneration signals. [ABSTRACT FROM AUTHOR]

Objectives: The objective of this study was to evaluate the influence of neutralizing a 2.5% NaOCl solution on its cytotoxicity, genotoxicity, and tissue-dissolving potential. Study design: The cytotoxicity and the genotoxicity of Dakin, a 2.5% NaOCl solution, and a neutralized 2.5% NaOCl solution were assessed according to ISO 10993 standards. The weight of palatal mucosa samples placed in neutralized 2.5% NaOCl, 2.5% NaOCl was recorded over time as well as the pH of the solutions. Results: The neutralized 2.5% NaOCl solution was 10-fold more cytotoxic than the 2.5% NaOCl solution. None of the solutions was genotoxic. The 2.5% NaOCl solution had a better tissue-dissolving capacity than the neutralized 2.5% NaOCl solution. The pH of the 2.5% NaOCl solution and neutralized 2.5% NaOCl solution decreased from 12 to 9 and from 7.5 to 5.6, respectively. Conclusion: Neutralizing a 2.5% NaOCl solution increased its cytotoxicity, did not induce any genotoxic effect, and reduced its tissue-dissolving ability. [Copyright &y& Elsevier]

Objectives: The aim was to evaluate the shelf life and the dissolving and antibacterial properties of a neutralized 2.5% NaOCl solution. Study design: The loss of available chlorine and the pH of the neutralized 2.5% NaOCl solution were recorded to determine its shelf life. The dissolving action on bovine dental pulp was assessed measuring weight loss, pH variation, and decrease in available chlorine content. The antibacterial activity was evaluated on artificially infected human teeth. The roots were endodontically prepared, sterilized, and inoculated with Enterococcus faecalis before irrigation with the neutralized solution. The presence of intracanal bacteria after irrigation was recorded. Results: The neutralized solution presented a shelf life of 2 hours, dissolving capacities equivalent to control for the first 5 minutes, and a better antibacterial efficiency. Conclusion: The neutralized 2.5% NaOCl solution must be used within 2 hours after mixing, should be frequently renewed to maintain its dissolving capacities, and presented enhanced antibacterial properties. [Copyright &y& Elsevier]

Objective: The aim of this study was to determine if there is a significant correlation between the in vivo presence of periapical radiolucency and ex vivo apical dye penetration on the same human teeth. Study design: Eighty-four endodontically filled teeth that were scheduled for extraction were classified into 2 groups according to the presence or absence of a periapical radiolucency and further divided into 2 subgroups according to the quality of the root canal filling. After extraction, the apical filling was evaluated by a dye penetration method. Results: The dye extraction evaluation showed no correlation between apical dye penetration and the presence of a periapical radiolucency (not significant), but a statistically significant correlation with the quality of the root canal filling (P = .03). Conclusion: The results of the dye penetration study were correlated to the quality of the root canal filling but had no predictive value for the development of periapical radiolucency. [Copyright &y& Elsevier]

Objectives: The incidence of bacterial microleakage, pulp inflammation and necrosis associated with dentine etching treatments prior to restoration are not known. Consequently, to resolve some of the controversy surrounding the effects and importance of vital dentine etching, the authors investigated these factors.Methods: 110 standardised class V cavities were cut into buccal dentine, without exposing the pulp of teeth scheduled for extraction for orthodontic reasons. Cavities were either left unetched, or etched with the non-equivalent treatments of phosphoric acid gel for 60s or Ethylenediaminetetraacetic acid (EDTA) for 30s, prior to placement of composite resin. Teeth were collected and pulp responses were evaluated according to ISO guidelines, using pathohistomorphometric analysis and ANOVA statistics.Results: Etching was found to be correlated to bacterial microleakage (p=0.0001) and tertiary dentine formation (p=0.0023). Bacterial microleakage was correlated to inflammatory activity (p=0.0001). The frequency of bacterial microleakage was: no etching (65%), EDTA (51%) and phosphoric acid (PA) (20%).Significance: Vital dentine etching treatment is of extreme importance for the placement of RC to minimise bacterial microleakage. PA etching proved to be more effective at preventing bacterial microleakage than non-etching, and etching with EDTA. [ABSTRACT FROM AUTHOR]

• The dentin/pulp tissue analogue may be used for cytotoxicity assessment of resinous cements. • The composition of the lower compartment (pulp component) affects its stiffness and biological properties. • The resinous cements investigated using the dentin/pulp tissue analogue showed variable but mild cytotoxicity. • Angiogenesis was not severely affected by the resinous cements under investigation. A three-dimensional (3D) dentin/pulp tissue analogue, resembling the human natural tissue has been engineered in an in vitro setup, aiming to assess the cytocompatibility of resin-based dental restorative cements. Stem Cells from Apical Papilla (SCAP) and Human Umbilical Vein Endothelial Cells (HUVEC) were embedded in Collagen-I/Fibrin hydrogels at 1:3 ratio within 24-well plates. Hanging culture inserts were placed over the hydrogels, housing an odontoblast-like cell layer and a human treated-dentin barrier. Shear modulus of the hydrogels at 3.5 and 5 mg/ml was evaluated by dynamic mechanical analysis. Eluates of two resin-based cements, a dual-cure- (Breeze™, Pentron: Cement-1/C1), and a self-adhesive cement (SpeedCEMplus™, Ivoclar-Vivadent: Cement-2/C2) were applied into the dentin/pulp tissue analogue after pre-stimulation with LPS. Cytocompatibility was assessed by MTT assay, live/dead staining and real-time PCR analysis. Both hydrogel concentrations showed similar shear moduli to the natural pulp until day (D) 7, while the 5 mg/ml-hydrogel substantially increased stiffness by D14. Both cements caused no significant toxicity to the dentin/pulp tissue analogue. C1 induced stimulation (p < 0.01) of cell viability (158 ± 3%, 72 h), while pre-stimulation with LPS attenuated this effect. C2 (±LPS) caused minor reduction of viability (15–20%, 24 h) that recovered at 72 h for the LPS+ group. Both cements caused upregulation of VEGF , ANGP-1 , and downregulation of the respective receptors VEGFR-2 and Tie-1. Both resin-based cements showed good cytocompatibility and triggered angiogenic response within the dentin/pulp tissue analogue, indicating initiation of pulp repair responses to the released xenobiotics. [ABSTRACT FROM AUTHOR]

Abstract The interrelations between inflammation and regeneration are of particular significance within the dental pulp tissue inextensible environment. Recent data have demonstrated the pulp capacity to respond to insults by initiating an inflammatory reaction and dentin pulp regeneration. Different study models have been developed in vitro and in vivo to investigate the initial steps of pulp inflammation and regeneration. These include endothelial cell interaction with inflammatory cells, stem cell interaction with pulp fibroblasts, migration chambers to study cell recruitment and entire human tooth culture model. Using these models, the pulp has been shown to possess an inherent anti-inflammatory potential and a high regeneration capacity in all teeth and at all ages. The same models were used to investigate the effects of tricalcium silicate-based pulp capping materials, which were found to modulate the pulp anti-inflammatory potential and regeneration capacity. Among these, resin-containing materials such as TheraCal® shift the pulp response towards the inflammatory reaction while altering the regeneration process. On the opposite, resin-free materials such as Biodentine™ have an anti-inflammatory potential and induce the pulp regeneration capacity. This knowledge contradicts the new tendency of developing resin-based calcium silicate hybrid materials for direct pulp capping. Additionally, it would allow investigating the modulatory effects of newly released pulp capping materials on the balance between tissue inflammation and regeneration. It would also set the basis for developing future capping materials targeting these processes. [ABSTRACT FROM AUTHOR]

Cell adhesion is crucial for many types of cell, conditioning differentiation, proliferation, and protein synthesis. As a mechanical process, cell adhesion involves forces exerted by the cytoskeleton and transmitted by focal adhesions to extracellular matrix. These forces constitute signals that infer specific biological responses. Therefore, analyzing mechanotransduction during cell adhesion could lead to a better understanding of the mechanobiology of adherent cells. For instance this may explain how, the shape of adherent stem cells influences their differentiation or how the stiffness of the extracellular matrix affects adhesion strength. To assess the mechanical signals involved in cell adhesion, we computed intracellular forces using the Cytoskeleton Divided Medium model in endothelial cells adherent on micropost arrays of different stiffnesses. For each cell, focal adhesion location and forces measured by micropost deflection were used as an input for the model. The cytoskeleton and the nucleoskeleton were computed as systems of multiple tensile and compressive interactions. At the end of computation, the systems respected mechanical equilibrium while exerting the exact same traction force intensities on focal adhesions as the observed cell. The results indicate that not only the level of adhesion forces, but also the shape of the cell has an influence on intracellular tension and on nucleus strain. The combination of experimental micropost technology with the present CDM model constitutes a tool able to estimate the intracellular forces. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: A Ca3SiO5-based cement has been developed to circumvent the shortcomings of traditional filling materials. The purpose of this work was to evaluate its genotoxicity, cytotoxicity and effects on the target cells’ specific functions. Methods: Ames’ test was applied on four Salmonella typhimurium strains. The micronuclei test was studied on human lymphocytes. The cytotoxicity (MTT test), the Comet assay and the effects on the specific functions by immunohistochemistry were performed on human pulp fibroblasts. Results: Ames’ test did not show any evidence of mutagenicity. The incidence of lymphocytes with micronuclei and the percentage of tail DNA in the Comet assay were similar to the negative control. The percentage of cell mortality with the new cement as performed with the MTT test was similar to that of biocompatible materials such as mineral trioxide aggregate (MTA) and was less than that obtained with Dycal. The new material does not affect the target cells’ specific functions such as mineralization, as well as expression of collagen I, dentin sialoprotein and Nestin. Significance: The new cement is biocompatible and does not affect the specific functions of target cells. It can be used safely in the clinic as a single bulk restorative material without any conditioning treatment. It can be used as a potential alternative to traditionally used posterior restorative materials. [Copyright &y& Elsevier]

Abstract: Objectives: To evaluate the cytotoxicity of Shellac F, a new fluoride varnish, and its effects on human dentin hydraulic conductance. Methods: Shellac F was compared to another fluoride varnish (Duraphat®) and a fluoride containing desensitizing agent (Isodan®). The cytotoxicity test was performed on human gingival fibroblasts and through dentin slice on human pulp fibroblasts. The hydraulic conductance (Lp) was recorded by fluid filtration with a Flodec device under a constant pressure (15cm H2O). The treated surface of the dentin disks and their sections were also investigated with SEM. Results: The cytotoxicity test on gingival fibroblasts revealed that Duraphat® was the least cytotoxic material, followed by Shellac F then Isodan®. With dentin slice interposition, a lower level of cytotoxicity was obtained. All of them showed a lower cytotoxicity decreasing on further dilutions (p <0.001). The measurement of hydraulic conductance showed that all materials resulted in a significant decrease in dentin permeability after 24h comprising between 60 and 76%, but there was no statistically significant difference among the materials. This decrease was still over 50% of the initial values after 7 days for all three materials. SEM investigation showed dentin tubules covered with a thick layer of Shellac F or Duraphat® whilst no material was observed on dentin surfaces treated with Isodan®. Significance: Shellac F showed an adequate cellular compatibility and a significant effect on human dentin hydraulic conductance. This indicates that the new material is safe and seems to be effective as a potential desensitizing agent. [Copyright &y& Elsevier]

Summary: In restorative dentistry, whilst moderate carious lesion treatment does not significantly compromise odontoblast cell survival, deep cavity preparation may lead to a partial death of these cells. However, newly formed odontoblast-like cells can replace the necrotic odontoblasts and secrete a reparative dentine matrix. Although several lines of evidence strongly suggest the presence of resting progenitor or stem cells in the dental pulp, little is known about the activation and migration of these cells in response to injury. Human immature third molars extracted for orthodontic reasons were used in this work to study the activation of progenitor/stem cells and their migration after deep cavity preparation involving in pulpal exposure using 5-bromo-2′-deoxyuridine labelling (BrdU). After incubation for 1 day, the BrdU was localised to the nuclei of cells in the perivascular area. The BrdU-immunolabelling exhibited a gradient. It was strong in the blood vessels surrounding the pulpal cavity and decreased in those away from the cavity. After incubation for 2 weeks, labelled cells were seen in the vicinity of the cavity. At 4 weeks, the immunolabelling was localised to the cavity area only. Control teeth without cavities or with shallow dentine cavities did not show any perivascular labelling after culture. These results clearly demonstrate that perivascular progenitor/stem cells can proliferate in response to odontoblast injury. They also show that these proliferating cells can migrate to the pulpal injury site in their tissue of origin simulating the situation in vivo. [Copyright &y& Elsevier]

Summary: In restorative dentistry, deep cavity preparation may lead to partial destruction of the odontoblastic layer. However, newly formed odontoblast-like cells can replace the necrotic odontoblasts and secrete a reparative dentine matrix. While growth factors such as transforming growth factor β1 (TGFβ1) and bone morphogenetic proteins (BMP-2 and BMP-4) seem to be involved in the proliferation and differentiation of pulp cells, little is known about the migration of the newly proliferating stem cells to the injury site. Our hypothesis was that endothelial cell injury may be involved in directing these cells towards the injury site. For this study, human pulp fibroblasts and L929 cells were fluorescence-labeled by transduction with the Enhanced Green Fluorescent Protein (EGFP). Similarly, human umbilical vein endothelial cells (HUVEC) were labeled with the Discosoma Red Fluorescent Protein-2 (DsRed2). Cell migration was then studied in an insert cell culture system. The HUVEC cells were cultured in the lower compartment while the human pulp fibroblasts or L929 were in the upper compartment. After artificial injury to the HUVEC cells, only human pulp fibroblasts migrated to the lower compartment. At early time periods (4 days), migrating cells were randomly localized on the HUVEC layer. However, after 14 and 20 days, they were perfectly aligned along the injury site. In the absence of injury, no migration was observed. These results suggest that, the endothelial injury is involved in the recruitment of odontoblast-like cells at the injury site. [Copyright &y& Elsevier]