Search

Prosthetic implants are widely used in dentistry and orthopedics and, as a result, infections can occur which cause their removal. Therefore, it is essential to propose methods of eradicating the bacteria that remain on the prosthesis during treatment. For this purpose, it is necessary to develop surfaces whose antibacterial activity can be controlled. Herein, we designed innovative and smart phosphonium self-assembled monolayer (SAM) interfaces that can be electrically activated on demand for controlling bacterial contaminations on solid surfaces. Upon electroactivation with a low potential (0.2 V for 60 min., conditions determined through a DOE), a successful stamping out of Gram-positive and Gram-negative bacterial strains was obtained with SAM-modified titanium surfaces, effectively killing 95% of Staphylococcus aureus and 90% Klebsiellapneumoniae. More importantly, no toxicity towards eukaryotic cells was observed which further enhances the biocompatible character of these novel surfaces for further implementation. [ABSTRACT FROM AUTHOR]

Purpose: To compare teeth prepared to receive a metallic versus a metal-ceramic crown with respect to (1) in vitro dentin permeability before and after using a desensitizing agent and (2) pulpal eugenol concentration after sealing a temporary crown with a zinc oxide-eugenol based cement. Materials and Methods: The roots of 20 human mandibular molars were separated and the crowns were prepared to receive a metallic crown. The hydraulic conductance was recorded before and after using Protect dentin desensitizer. The crowns were then further reduced to receive a metal-ceramic crown and the hydraulic conductance was recorded under the same conditions, on deeper dentin, before and after using the desensitizing agent. Twenty additional teeth were prepared: 10 to receive a metallic crown and 10 teeth to receive a metal-ceramic crown. A tube filled with 1 mL phosphate buffered saline (PBS) was sealed to the cementoenamel junction. A temporary crown was sealed onto the preparation with Temp Bond. The amount of eugeno] that diffused across dentin into PBS was spectrofluorimetrically measured at Day 1 and Day 7. The crown preparations were vertically sectioned and the dentin remaining thickness was recorded. Results: The hydraulic conductance of teeth prepared for a metal-ceramic crown was twice as high as teeth prepared for a metallic crown (P<0.001). The desensitizing agent reduced the hydraulic conductance in both groups (P< 0.001). The two groups showed the same hydraulic conductance after using Protect (ns). No significant difference was found in the amount of eugenol diffusion between the two groups of teeth although eugenol diffusion decreased with time (P< 001). No correlation was found between eugenol diffusion and remaining dentin thickness. [ABSTRACT FROM AUTHOR]

Purpose: To compare in vitro the efficacy of five resin-based desensitizing agents at reducing human dentin permeability and to compare their cytotoxicity. The tested hypothesis was that their different curing techniques cause variations in efficiency and cytotoxicity. Materials and Methods: Dentin slices (0.5 ± 0.05 mm thick) were prepared from human third molars (10 per group) and their hydraulic conductance was recorded before and after application of one of the desensitizing agents with a Fludec device. Six desensitizing agents were studied: one light curing agent (Seal and Protect); one self-curing agent (Pain Free); three resin-based agents without any polymerization initiator (Health-Dent, Gluma Desensirizer, Isodan); one oxalate-based agent served as a control (Protect). A MTT assay on L 929 fibroblasts was performed to measure the cytotoxicity of the six desensitizing agents applied onto additional dentin slices (10 per group). Results: All the desensitizing agents resulted in a large decrease in dentin permeability. The best results were obtained with Gluma Desensitizer, Isodan, Pain Free and Protect. A statistically significant difference was found among the materials (P= 0.001). All the materials were non-cytotoxic. Cell viability ranged from 88% for Seal and Protect to 100% for Isodan. No difference was found among their cytotoxicity. [ABSTRACT FROM AUTHOR]

Purpose: To investigate pulpal injury by measuring odontoblast numbers, and pulp dentin repair activity by measuring reactionary dentin area, in relation to the remaining dentin thickness (RDT) of cavity preparations in 217 human teeth. Materials and Methods: Cavities were restored with adhesive bonded composite, resin-modified glass-ionomer cement, zinc oxide-eugenol or calcium hydroxide materials. The teeth were extracted for orthodontic reasons between 20-381 days post-operatively, and odontoblast numbers and reactionary dentin area were analyzed histomorphometrically, and statistically using ANOVA. Results: Reactionary dentin deposition was observed beneath cavities with a RDT above 0.5 mm as well as beneath cavities with a RDT below 0.25 mm; however maximal reactionary dentin appeared to be beneath cavities with an a RDT between 0.5-0.25 mm (P= 0.0001). The area of reactionary repair was also influenced by the choice of restoration material (P= 0.0385) bam greatest to least; calcium hydroxide, composite, resin-modified glass-ionomer cement and zinc oxide-eugenol. Odontoblast numbers were maintained beneath cavities with a RDT above 0.25 mm, cavities placed closer to the pulp appeared to injure underlying odontoblasts, reducing their numbers (P= 0.0001). The choice of cavity restoration material also influenced the survival of underlying odontoblasts (P= 0.0061). [ABSTRACT FROM AUTHOR]

Complement C5a protein has been shown to play a major role in tissue regeneration through interaction with its receptor (C5aR) on target cells. Expression of this receptor has been reported in the nervous system which, upon injury, has no treatment to restore the lost functions. This work aimed at investigating the Complement C5a effect on axonal growth after axotomy in vitro. Primary hippocampal neurons were isolated from embryonic Wistar rats. Cell expression of C5aR mRNA was verified by RT-PCR while its membrane expression, localization, and phosphorylation were investigated by immunofluorescence. Then, the effects of C5a on injured axonal growth were investigated using a 3D-printed microfluidic device. Immunofluorescence demonstrated that the primary cultures contained only mature neurons (93%) and astrocytes (7%), but no oligodendrocytes or immature neurons. Immunofluorescence revealed a co-localization of NF-L and C5aR only in the mature neurons where C5a induced the phosphorylation of its receptor. C5a application on injured axons in the microfluidic devices significantly increased both the axonal growth speed and length. Our findings highlight a new role of C5a in regeneration demonstrating an enhancement of axonal growth after axotomy. This may provide a future therapeutic tool in the treatment of central nervous system injury. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the influence of dentin etching with phosphoric acid on hydrogen peroxide diffusion through human dentin in internal bleaching. Methods: 46 human premolars were extracted for orthodontic reasons from adolescents. The teeth were endodontically treated and a flat defect was created at the enamel-cementum junction. The teeth were divided into two groups: the access cavity was etched for 30 seconds with 35% H3P04 in the first group and left intact in the second group. The teeth were filled with 20μL of 35% hydrogen peroxide gel. The receiving medium on the other side was renewed at Day 1, Day 2 and Day 7 to quantify the diffusing hydrogen peroxide. An analysis of variance was performed to compare the diffusion between the two groups. Results: This work demonstrated a higher hydrogen peroxide diffusion when the access cavity was etched (P< 0.01). [ABSTRACT FROM AUTHOR]

Aims: Dental pulp stem cells (DPSCs) contain a population of stem cells with a broad range of differentiation potentials, as well as more lineage‐committed progenitors. Such heterogeneity is a significant obstacle to experimental and clinical applications. The aim of this study is to isolate and characterize a homogenous neuronal progenitor cell population from human DPSCs. Methodology: Polysialylated‐neural cell adhesion molecule (PSA‐NCAM+) neural progenitors were isolated from the dental pulp of three independent donors using magnetic‐activated cell sorting (MACS) technology. Immunofluorescent staining with a panel of neural and non‐neural markers was used to characterize the magnetically isolated PSA‐NCAM+ fraction. PSA‐NCAM+ cells were then cultured in Neurobasal A supplemented with neurotrophic factors: dibutyryl cyclic‐AMP, neurotrophin‐3, B27 and N2 supplements to induce neuronal differentiation. Both PSA‐NCAM+ and differentiated PSA‐NCAM+ cells were used in Ca2+ imaging studies to assess the functionality of P2X3 receptors as well as membrane depolarization. Results: PSA‐NCAM+ neural progenitors were isolated from a heterogeneous population of hDPSCs using magnetic‐activated cell sorting and anti‐PSA‐NCAM MicroBeads. Flow cytometry analysis demonstrated that immunomagnetic sorting significantly increased the purity of PSA‐NCAM+ cells. Immunofluorescent staining revealed expression of pan‐neuronal and mature neuronal markers, PGP9.5 and MAP2, respectively, as well as weak expression of the mature sensory markers, peripherin and islet1. ATP‐induced response was mediated predominately by P2X3 receptors in both undifferentiated and differentiated cells, with a greater magnitude observed in the latter. In addition, membrane depolarizations were also detected in cells before and after differentiation when loaded with fast‐voltage‐responding fluorescent molecule, FluoVolt™ in response to potassium chloride. Interestingly, only differentiated PSA‐NCAM+ cells were capable of spontaneous membrane oscillations. Conclusions: In summary, DPSCs contain a population of neuronal progenitors with enhanced neural differentiation and functional neural‐like properties that can be effectively isolated with magnetic‐activated cell sorting (MACS). [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]

Tissue-engineered oral epithelium (ΤΕΟΕ) was developed after comparing various culture conditions, including submerged (SUB) and air-liquid interface (ALI) human cell expansion options. Barrier formation was evaluated via transepithelial electrical resistance (TEER) and calcein permeation via spectrofluorometry. TEOE was further assessed for long-term viability via live/dead staining and development of intercellular connections via transmission electron microscopy. Tissue architecture was evaluated via histochemistry and the expression of pancytokeratin (pCK) via immunohistochemistry. The effect of two commonly used dental resinous monomers on TEOE was evaluated for alterations in cell viability and barrier permeability. ALI/keratinocyte growth factor-supplemented (ALI-KGS) culture conditions led to the formation of an 8-20-layer thick, intercellularly connected epithelial barrier. TEER values of ALI-KGS-developed TEOE decreased compared with all other tested conditions, and the established epithelium intensively expressed pCK. Exposure to dental monomers affected the integrity and architecture of TEOE and induced cellular vacuolation, implicating hydropic degeneration. Despite structural modifications, the permeability of TEOE was not substantially affected after exposure to the monomers. In conclusion, the biological properties of the TEOE mimicking the physiological functional conditions and its value as biocompatibility assessment tool for dental materials were characterized.

Introduction: 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., Methods: 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., Results: 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., Conclusions: 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., (Copyright © 2021 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Objective: Experimental procedures have been used to monitor cellular responses at the dentin/pulp interface. Aiming to divert from in vivo studies and oversimplified two-dimensional assays, three-dimensional (3D) models have been developed. This review provides an overview of existing literature, regarding 3D in vitro dentin/pulp reconstruction., Material & Methods: PubMed, Scopus, Cochrane Library and Web of Science- were systematically searched for attributes between 1998 and 2020. The search focused on articles on the development of three-dimensional tools for the reconstruction of a dentin/pulp complex under in vitro conditions, which were then screened and qualitatively assessed. Article grouping according to mode of implementation, resulted in five categories: the customised cell perfusion chamber (CPC) (n = 8), the tooth bud model (TBM) (n = 3), the 3D dentin/pulp complex manufactured by tissue engineering (DPC) (n = 6), the entire tooth culture (ETC) (n = 4) and the tooth slice culture model (TSC) (n = 5)., Results: A total of 26 publications, applying nine and eight substances for pulp and dentin representation respectively, were included. Natural materials and dentin components were the most widely utilized. The most diverse category was the DPC, while the CPC group was the test with the highest longevity. The most consistent categories were the ETC and TSC models, while the TBM presented as the most complete de novo approach., Conclusions: All studies presented with experimental protocols with potential upgrades. Solving the limitations of each category will provide a complete in vitro testing and monitoring tool of dental responses to exogenous inputs., Clinical Relevance: The 3D dentin/pulp complexes are valid supplementary tools for in vivo studies and clinical testing. Graphical Abstract.

Purpose: To assess the influence of in-office whitening gel pH on whitening efficiency., Methods: Hydrogen peroxide diffusion and color changes on bovine teeth were assessed. Three gels with close hydrogen peroxide concentrations but with various pH levels were tested: Zoom 2 (Discus Dental), Opalescence Endo and Opalescence Boost (Ultradent). The pH levels were respectively: 3.0, 5.0 and 7.0. Thirty enamel slices and tooth crowns were used for both studies (n = 10 per group per study). Hydrogen peroxide diffusion through the enamel slices and the tooth crowns was spectrophotometrically recorded every 10 minutes for 1 hour to calculate the diffusion coefficients. Color changes were spectrophotometrically recorded every 10 minutes for 1 hour and quantified in term of CIE-Lab., Results: The hydrogen peroxide diffusion coefficient through enamel ranged from 5.12 +/- 0.82 x 10(-9) cm2 s(-1) for pH 3 to 5.19 +/- 0.92 x 10(-9) cm2 S(-1) for pH 7. Through tooth crowns it ranged from 4.80 +/- 1.75 x 10(-10) cm2 s(-1) for pH 5 to 4.85 +/- 1.82 x 10(-10) cm2 s(-1) for pH 3. After 1 hour, the deltaE varied from 5.6 +/- 4.0 for pH 7 to 7.0 +/- 5.0 for pH 3 on enamel slices and from 3.9 +/- 2.5 for pH 5 to 4.9 +/- 3.5 for pH 7 on tooth crowns. There was no statistically significant difference between groups for both parameters.

The purpose of this work is to produce microspheres loaded with transforming growth factor beta1 TGFbeta1 and basic fibroblast growth factor FGF-2; to ensure the protein protection from degradation during the encapsulation and storage steps, to evaluate the release rate and the microspheres toxicity. The water in oil in water double emulsion technique was adapted to avoid the protein degradation during the encapsulation. The obtained microspheres were deeply characterized to evaluate their size, morphology, toxicity, the way of degradation, the protein stability and release rate. The microspheres were found to be biocompatible and the encapsulation efficiency was about 35%. It was observed that the obtained microspheres increase the shelf life of the growth factors. The diffusion coefficient was quantified using Fick's law of diffusion that was combined to an empirical equation representing the decrease in the protein stability. Such modelling helped to give indirect information about the microspheres morphology and drug distribution within the microspheres. The main conclusion consists of the formation of a higher compact polymer matrix when smaller particles are produced, which has different distinct effects: the encapsulation efficiency and the stability of the encapsulated growth factor are enhanced while both the growth factor diffusion and the polymer degradation rates decrease.

Odontoblasts are highly differentiated postmitotic cells, which under pathological conditions such as carious lesions and dental injuries may degenerate and be replaced by other pulp cells. A recent work showed that this physiological event can be reproduced in an in vitro assay system. The purpose of the present study was to evaluate the effects of resinous monomers on odontoblast differentiation in vitro. Pulp cores from extracted human third molars were cultured with beta-glycerophosphate (2 mM) and used to evaluate the effects of TEGDMA, HEMA, UDMA, and Bis-GMA on the differentiation of pulp fibroblasts into odontoblasts. The effect of the monomers was studied by evaluating the expression of several odontoblast specific genes. In the absence of monomers, mineral nodule formation was observed. Pulp cells contributing to the nodule formation synthesized type I collagen, osteonectin, and dentin sialoprotein (DSP). In addition, Fourier transform infrared microspectroscopy showed that the mineral and organic composition of the nodules were characteristic of dentin. When the monomers were added at nontoxic concentrations, the effects of HEMA and Bis-GMA were more evident than that of TEGDMA and UDMA on collagen 1, osteonectin, and DSP expression. However, all monomers significantly decreased DSP expression and completely inhibited the mineral nodule formation., (Copyright 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 418-423, 2002)